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矢口 裕之
| 理工学研究科 数理電子情報部門 | 教授 |
| 工学部 電気電子物理工学科 |
研究者情報
■ 学位■ 研究キーワード
■ 研究分野
■ 学歴
- 1988年04月 - 1991年03月, 東京大学, 工学系研究科, 物理工学専攻
- 1986年04月 - 1988年03月, 東京大学, 工学系研究科, 物理工学専攻, 日本国
- 1986年, 東京大学, 工学部, 物理工学科, 日本国
- 応用物理学会, 応用物理学会論文賞委員, 学協会
- 国立研究開発法人物質・材料研究機構, 機能性材料拠点構想アドバイザリー委員会委員
- 独立行政法人日本学術振興会, 国際事業委員会 書面審査員・書面評価員
- 独立行政法人日本学術振興会, 特別研究員等審査会 専門委員
- 独立行政法人日本学術振興会, 特別研究員等審査会専門委員及び国際事業委員会書面審査員・書面評価員
- 応用物理学会, 論文誌企画・編集委員会委員, 学協会
- 応用物理学会, 代議員, 応用物理学会, 学協会
業績情報
■ 論文- Analysis of two-step photocurrent generation in GaAs:N-based intermediate band solar cells with utilization of device simulation
Md Faruk Hossain; Shuhei Yagi; Hiroyuki Yaguchi
AIP Advances, 巻：15, 号：2, 2025年02月, ［査読有り］
We developed a novel approach to analyze the two-step photocurrent generation process in intermediate band solar cells (IBSCs) by means of numerical device simulation combined with rate equation analysis. An IBSC having a GaAs:N intermediate band (IB) absorber with the same layered structure as experimentally investigated in our previous work is modeled, and its characteristic behavior of external quantum efficiency (EQE) is successfully simulated with the utilization of Silvaco-Atlas software. The simulated results gave new insights into the material parameters of the device, such as trap states and interface recombination velocity, and revealed that an electron-blocking layer adjacent to the IB absorber plays a significant role in confining the electrons in the IB state, which is the main prerequisite for efficient two-step photocurrent generation. Change in EQE (ΔEQE) induced by additional light illumination of which energy is below the valence band–IB gap is analyzed as an evaluation metric of two-step photocurrent generation based on a rate equation analysis. The integrated electron concentration in the GaAs:N absorber layer is calculated from the simulation results and is used as an input parameter for the rate equation analysis. As a result, the bias voltage-dependent ΔEQE of experimentally investigated IBSC is well reproduced, indicating that the proposed method can be a useful approach for a better understanding of IBSC operation physics and designing more efficient devices.
AIP Publishing, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/5.0247676
DOI ID：10.1063/5.0247676, eISSN：2158-3226 - Spontaneous Heterointerface Modulation by a Methylammonium Tetrafluoroborate Additive for a Narrow-Bandgap FAPbI3 Photoabsorber in Perovskite Solar Cells
Daisuke Kubota; Ryuzi Katoh; Hiroyuki Kanda; Hiroyuki Yaguchi; Takurou N. Murakami; Naoyuki Nishimura
ACS Applied Materials & Interfaces, 巻：16, 号：40, 開始ページ：53918, 終了ページ：53929, 2024年09月, ［査読有り］
American Chemical Society (ACS), 研究論文（学術雑誌）
DOI：https://doi.org/10.1021/acsami.4c11784
DOI ID：10.1021/acsami.4c11784, ISSN：1944-8244, eISSN：1944-8252 - Estimation of Junction Temperature in Single 228 nm‐Band AlGaN Far‐Ultraviolet‐C Light‐Emitting Diode on c‐Sapphire Having 1.8 mW Power and 0.32% External Quantum Efficiency
Muhammad Ajmal Khan; Mitsuhiro Muta; Kohei Fujimoto; Javier Gonzalez Rojas; Pablo Fredes; Ernesto Gramsch; Yasushi Iwaisako; Hiroyuki Yaguchi; Hideki Hirayama
physica status solidi (a), 巻：221, 号：21, 2024年05月, ［査読有り］
The increasing resistance of methicillin‐resistant Staphylococcusaureus to antibiotics is a major challenge faced by mankind in thehistory of medical science and according to United Nations, 700‐000 patients worldwide die every year from an infection with multidrug‐resistant organisms (MROs). Aluminum gallium nitride‐based 228 nm Far‐ultraviolet‐C (Far‐UVC) lightsources can be safely used as a germicidal application in both manned as wellas in unmanned environments against these MROs. Previously, the 228 nm Far‐UVC light‐emitting diode (LED) with emission power of 1 mW was reported by ourgroup, however, the value of external quantum efficiency (EQE) was not reportedusing conventional thick Ni (20 nm)/Au (100 nm) p‐electrode. Herein, animproved Far‐UVC LED on c‐Sapphire is attempted using a special technique in SR4000 type of metal‐organic chemical vapor deposition reactor to control the Al composition in n‐AlGaN buffer and across the 2 inch‐wafer. As a result, the light emission power of 1.8 mW and EQE of 0.32% in 228 nm Far‐UVC LED aresuccessfully achieved using very thin p‐electrode (Ni/Au). However, arelatively high junction temperature of ≈100°C around thejunction of Far‐UVC LED is observed. Finally, some simple heat‐sink modules forheat dissipation of Far‐UVC LED panel with light power of 30 mW are implemented.
Wiley, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssa.202400064
DOI ID：10.1002/pssa.202400064, ISSN：1862-6300, eISSN：1862-6319 - Nitrogen Concentration Dependence of Two‐Step Photocurrent Generation by Below‐Gap Excitation in GaPN Alloys
Abdul Qayoom; Shuhei Yagi; Hiroyuki Yaguchi
physica status solidi (b), 巻：261, 号：4, 2024年02月, ［査読有り］
Two‐step photocurrent generation and its dependence on nitrogen concentration in GaPN alloys using two‐wavelength excited photocurrent (TWEPC) measurements are investigated. External quantum efficiency (EQE) measurements show an increase in the two‐step absorption of below‐gap excitation light through tail states at longer wavelengths and that the quasi‐direct gap redshifts as the nitrogen concentration increases. The improvement in the EQE at longer wavelengths is explained by the increased density of the tail states in GaPN with higher nitrogen concentrations. In contrast, the EQE decreases at shorter wavelengths with increasing nitrogen content. TWEPC results show that differential photocurrent density , which shows the synergy effect of multiple‐wavelength light, reduces with the addition of nitrogen. It is found from rate–equation analysis that the decrease in the EQE at shorter wavelengths and in is mainly due to the increased nonradiative recombination in GaPN with higher nitrogen concentration. The use of lattice‐matched alloys and a p‐type GaP capping layer as well as the optimization of the growth conditions can improve the EQE at shorter wavelengths and .
Wiley, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssb.202300369
DOI ID：10.1002/pssb.202300369, ISSN：0370-1972, eISSN：1521-3951 - Photocurrent enhancement by below bandgap excitation in GaPN
Abdul Qayoom; Sanjida Ferdous; Shuhei Yagi; Hiroyuki Yaguchi
Japanese Journal of Applied Physics, 巻：62, 号：SK, 開始ページ：SK1038, 終了ページ：SK1038, 2023年05月, ［査読有り］
Abstract
This study presents two-wavelength excited photocurrent (TWEPC) measurements in GaP1−xNx grown by metalorganic vapor phase epitaxy. TWEPC measurements reveal that photocurrent generation is significantly enhanced when above gap excitation and below gap excitation (BGE) sources are applied simultaneously. With increasing BGE photon energy, a large increase in photocurrent is observed. The external quantum efficiency measurements show that the effect of BGE light is higher with a higher density of tail states present. The extended numerical study by rate equations reproduced the results in a good manner. Furthermore, the simulation results showed that the addition of the BGE light affects the electron occupancy as well as the electron lifetime, which is found to be 0.1 ns in this study.
IOP Publishing, 研究論文（学術雑誌）
DOI：https://doi.org/10.35848/1347-4065/acd00c
DOI ID：10.35848/1347-4065/acd00c, ISSN：0021-4922, eISSN：1347-4065 - Significant improvement of injection efficiency in deep-UV LD structures by light Mg doping in p-core layer
Yuri Itokazu; Noritoshi Maeda; Hiroyuki Yaguchi; Hideki Hirayama
Japanese Journal of Applied Physics, 2023年04月, ［査読有り］
研究論文（学術雑誌）
DOI：https://doi.org/10.35848/1347-4065/acbda4
DOI ID：10.35848/1347-4065/acbda4, ORCID：129359119 - Effects of carrier-blocking barrier height on two-step photocurrent generation in dilute nitride intermediate band solar cells
Shuhei Yagi; Shun Numata; Yasushi Shoji; Yoshitaka Okada; Hiroyuki Yaguchi
Japanese Journal of Applied Physics, 巻：62, 号：SK, 開始ページ：SK1008, 終了ページ：SK1008, 2023年03月, ［査読有り］
Abstract
GaAs:N dilute nitride intermediate band solar cells (IBSCs) with different barrier heights for blocking electron transport from the intermediate band (IB) were prepared and the role of such an electron blocking layer (EBL) was investigated. It is found that the EBL effectively confines electrons in the IB states, and the two-step photocurrent generation process is strongly affected by its barrier height. A rate equation analysis well reproduced experimental observations of the applied voltage dependence of the two-step photocurrent generation process. It revealed that the electron extraction both from the conduction band and the IB through the EBL is governed by the thermionic emission process. To meet the requirements of an ideal IBSC, optimized device structures including the barrier height of the EBL have to be designed properly taking into account the material parameters and carrier dynamics under the actual operating condition.
IOP Publishing, 研究論文（学術雑誌）
DOI：https://doi.org/10.35848/1347-4065/acbf5e
DOI ID：10.35848/1347-4065/acbf5e, ISSN：0021-4922, eISSN：1347-4065 - Detection of Nonradiative Recombination Centers in GaPN by Combining Two‐Wavelength Excited Photoluminescence and Time‐Resolved Photoluminescence
Sanjida Ferdous; Hiroki Iwai; Norihiko Kamata; Hiroyuki Yaguchi; Shuhei Yagi
physica status solidi (b), 巻：258, 号：11, 開始ページ：2100119, 終了ページ：2100119, 2021年11月, ［査読有り］
Presence and influence of nonradiative recombination (NRR) centers in an intermediate band (IB)-type material, GaP1–xNx ((Formula presented.)), are studied by two-wavelength excited photoluminescence (TWEPL) method and time-resolved photoluminescence (TRPL) measurement at 77 K. With the use of below-gap excitation (BGE) light in addition to an above-gap excitation (AGE), the PL peak intensity is found to increase which indicates the presence of NRR centers and a secondary excitation from the IB to conduction band (CB). Depending on the effect of different BGE energies, an energy diagram on the distribution of NRR centers and NRR process is interpreted. The saturation of PL increase is attributed to the trap-filling effect in NRR centers, which allows us to modify the rate equation. The NRR parameters are evaluated by a qualitative simulation of the modified rate equations of one-level model together with the lifetime determined by TRPL. In continuation of evaluating NRR parameters by rate equation analysis, the addition of TRPL measurement improves accuracy and approaches the determination of NRR parameters. A successful characterization of NRR centers leads to a proper optimization of IB-type solar cells (IBSCs).
Wiley, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssb.202100119
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85114326814&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85114326814&origin=inward
DOI ID：10.1002/pssb.202100119, ISSN：0370-1972, eISSN：1521-3951, SCOPUS ID：85114326814, Web of Science ID：WOS:000692804600001, 共同研究・競争的資金等ID：24508454 - Insights into Microscopic Crystal Growth Dynamics of CH3NH3PbI3 under a Laser Deposition Process Revealed by In Situ X-ray Diffraction
Tetsuhiko Miyadera; Yuto Auchi; Kohei Yamamoto; Noboru Ohashi; Tomoyuki Koganezawa; Hiroyuki Yaguchi; Yuji Yoshida; Masayuki Chikamatsu
ACS APPLIED MATERIALS & INTERFACES, 巻：13, 号：19, 開始ページ：22559, 終了ページ：22566, 2021年05月, ［査読有り］
The process dynamics for the vacuum deposition of methylammonium lead iodide (MAPbI(3)) perovskite was analyzed by in situ X-ray diffraction using synchrotron radiation. MAPbI(3) was fabricated by alternatingly supplying PbI2 and methylammonium iodide via a laser deposition system installed at the synchrotron beamline BL46XU at SPring-8, and in situ crystallization analysis was conducted. Microscopic insights into the crystallization were obtained, including observation of Laue oscillation during the PbI2 growth and octahedral unit (PbI6) rotation during the transformation into perovskite. On the basis of this analysis, conditions that favor the construction of atomically flat MAPbI3 perovskite films were deduced.
AMER CHEMICAL SOC, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1021/acsami.1c04488
DOI ID：10.1021/acsami.1c04488, ISSN：1944-8244, eISSN：1944-8252, Web of Science ID：WOS:000655027500046 - Solid State Devices and Materials FOREWARD
Mitsuru Takenaka; Osamu Nakatsuka; Hiroyuki Yaguchi
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：60, 号：SB, 2021年05月
IOP PUBLISHING LTD, 英語
DOI：https://doi.org/10.35848/1347-4065/abef61
DOI ID：10.35848/1347-4065/abef61, ISSN：0021-4922, eISSN：1347-4065, Web of Science ID：WOS:000635901600001 - Photoluminescence intensity change of GaP1-xNx alloys by laser irradiation
Md. Zamil Sultan; Akinori Shiroma; Shuhei Yagi; Kengo Takamiya; Hiroyuki Yaguchi
AIP ADVANCES, 巻：10, 号：9, 2020年09月, ［査読有り］
We report the influence of laser irradiation on photoluminescence (PL) intensity to study the evolution of nonradiative recombination centers in GaP1-xNx alloys. PL mapping measurements confirmed that defects to act as nonradiative recombination centers are permanently generated by laser irradiation, which results in irreversible degradation of the PL intensity. Real-time PL measurements revealed that stronger laser irradiation leads to a larger and faster decrease in the PL intensity with irradiation time. The decay of the PL intensity by laser irradiation is larger and faster for a lower nitrogen concentration, indicating that samples with a lower nitrogen concentration are abound with hidden defects to act as nonradiative recombination centers by laser irradiation. It was demonstrated that PL measurement using high-power density photoexcitation is useful to evaluate the generation or multiplication of irradiation-induced nonradiative defects, which causes the deterioration of optoelectronic devices during operation. (c) 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/5.0020793
DOI ID：10.1063/5.0020793, eISSN：2158-3226, ORCID：79669843, Web of Science ID：WOS:000567593300001, 共同研究・競争的資金等ID：24508454 - Epitaxial growth of CH3NH3PbI3 on rubrene single crystal
Tetsuhiko Miyadera; Yuto Auchi; Tomoyuki Koganezawa; Hiroyuki Yaguchi; Masayuki Chikamatsu
APL MATERIALS, 巻：8, 号：4, 開始ページ：041104, 終了ページ：041104, 2020年04月, ［査読有り］
CH3NH3PbI3 perovskite films were grown epitaxially on rubrene single crystals using the laser deposition method for the supply of the source materials (PbI2 and CH3NH3I). An atomically smooth surface with step-and-terrace structures was observed. Several types of crystal orientation were observed, which were dependent on the growth temperature and deposition conditions. For room temperature growth, the crystal orientation was correlated with the orientation of PbI2, which was also found to be grown epitaxially on the rubrene single crystal. In contrast, for growth at elevated temperatures, the crystal orientation with the smallest mismatch between rubrene and perovskite is produced. The construction of atomically ordered ideal perovskite crystals was verified. Moreover, a novel phenomenon was revealed where the octahedral PbI6 unit of PbI2 rotates vertically while retaining its lateral orientation. This growth mechanism results in a layer-by-layer growth and the construction of epitaxial perovskite films with atomic-order flat surfaces.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.5142307
DOI ID：10.1063/1.5142307, ISSN：2166-532X, ORCID：71441934, Web of Science ID：WOS:000523751500003 - Solid State Devices and Materials FOREWORD
Hiroyuki Yaguchi; Mitsuru Takenaka; Takuji Hosoi
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：59, 2020年04月
IOP PUBLISHING LTD, 英語
DOI：https://doi.org/10.35848/1347-4065/ab75df
DOI ID：10.35848/1347-4065/ab75df, ISSN：0021-4922, eISSN：1347-4065, Web of Science ID：WOS:000519630000001 - Enhanced Strain Relaxation in AlGaN Layers Grown on Sputter-Based AlN Templates
Yosuke Mogami; Atsushi Osawa; Kazuto Ozaki; Yukitake Tanioka; Atsushi Maeoka; Yuri Itokazu; Shunsuke Kuwaba; Masafumi Jo; Noritoshi Maeda; Hiroyuki Yaguchi; Hideki Hirayama
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 巻：257, 号：4, 2020年04月, ［査読有り］
Strain plays a crucial role in the performance of ultraviolet (UV) optoelectronic devices. The strain states of AlGaN layers grown on different AlN templates are investigated. Two types of AlN templates are prepared: one is grown solely by metal-organic chemical vapor deposition (MOCVD), and the other is fabricated with the combination of direct current (DC) sputtering, high-temperature annealing, and MOCVD growth. The qualities of 4 mu m-thick MOCVD AlN and 1.2 mu m-thick sputter-based AlN are almost equivalent in terms of dislocation density and surface morphology. However, the strain relaxation ratio of the AlGaN layer is higher for the 1.2 mu m sputter-based AlN than the 4 mu m MOCVD AlN, indicating that the strain state depends on the total thickness of the epilayers on the sapphire substrate. In addition, it is found that the curvature of the sample at room temperature is governed mainly by the thickness of the AlGaN layer. As a result, sputter-based AlN templates allow for the enhanced strain relaxation of the AlGaN layer with a small sample bowing.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssb.201900590
DOI ID：10.1002/pssb.201900590, ISSN：0370-1972, eISSN：1521-3951, Web of Science ID：WOS:000508664000001 - Detection of Nonradiative Recombination Centers in GaPN (N:0.105%) by Below-Gap Excitation Light
Sanjida Ferdous; Norihiko Kamata; Shuhei Yagi; Hiroyuki Yaguchi
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 巻：257, 号：2, 2020年02月, ［査読有り］
Investigation on cascade photo-excitation via intermediate band (IB) is promising for improving the efficiency of IB-type solar cells (IBSCs). Increasing nitrogen (N) concentration in GaP changes an ensemble of discrete N-N pair levels to form the IB as well as introducing defect levels acting as nonradiative recombination (NRR) centers. In continuation of detecting NRR centers in GaP1-xNx (x>0.5%), a study is made for the lower N concentration region of 0.105% to understand an original formation of defect levels and their properties. Elimination of temperature quenching by immersing the sample into liquid nitrogen reveals a distribution of NRR centers inside the forbidden energy gap and the shift of Fermi energy depending on above-gap excitation (AGE) density. Profound understanding of IB and defects of GaP1-xNx leads to a proper optimization of IBSCs.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssb.201900377
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85074068004&origin=inward
DOI ID：10.1002/pssb.201900377, ISSN：0370-1972, eISSN：1521-3951, ORCID：64953816, SCOPUS ID：85074068004, Web of Science ID：WOS:000489972400001, 共同研究・競争的資金等ID：24508454 - Spectral Change of E- Band Emission in a GaAs:N delta-Doped Superlattice Due to Below-Gap Excitation and Its Discrimination from Thermal Activation
Md Dulal Haque; Norihiko Kamata; A. Z. M. Touhidul Islam; Shuhei Yagi; Hiroyuki Yaguchi
JOURNAL OF ELECTRONIC MATERIALS, 巻：49, 号：2, 開始ページ：1550, 終了ページ：1556, 2020年02月, ［査読有り］
In this study, we examined the E- band luminescence of a GaAs:N delta-doped superlattice (SL) grown by metal organic vapor phase epitaxy with 0.15% nitrogen (N) using two-wavelength excited photoluminescence. It was observed that the photoluminescence (PL) intensity of the low-energy peak (P-2) at 1.38 eV of the E- band was quenched larger compared to the high-energy peak (P-1) at 1.41 eV. This was due to the superposition of below-gap excitation (BGE) light of energy 0.95 eV over the above-gap excitation light of energy 1.45 eV on the SL structure at a fixed temperature of 12 K. On the other hand, at higher temperatures, the PL intensity of the high-energy peak P-1 was quenched higher compared to the low-energy peak P-2 without any addition of the BGE light. We interpreted the experimental results by considering the carrier recombination (CR) model and concluded that the observed PL spectral and intensity change of the E- band emission due to BGE does not result from the thermal activation, but from the optical excitation among the E- band, conduction band, and CR levels in GaAs:N delta-doped structure. We concluded that to achieve high-efficiency intermediate band-type solar cells, it is essential to understand the CR mechanism through CR levels by determining their origin and eliminating them from the material.
SPRINGER, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1007/s11664-019-07856-6
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85075954109&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85075954109&origin=inward
DOI ID：10.1007/s11664-019-07856-6, ISSN：0361-5235, eISSN：1543-186X, ORCID：79739993, SCOPUS ID：85075954109, Web of Science ID：WOS:000500279100002 - Study of nonradiative recombination centers in GaAs:N δ-doped superlattices structures revealed by below-gap excitation light
Md. Dulal Haque; Norihiko Kamata; A. Z.M. Touhidul Islam; Md. Julkarnain; Shuhei Yagi; Hiroyuki Yaguchi; Yoshitaka Okada
5th International Conference on Computer, Communication, Chemical, Materials and Electronic Engineering, IC4ME2 2019, 2019年07月
Nonradiative recombination (NRR) centers in GaAs:N delta-doped superlattices (SLs) grown by molecular beam epitaxy (MBE) has been investigated by two-wavelength excited photoluminescence (TWEPL) method for conduction band scheme. The PL intensity of E{-} band of the samples with lower nitrogen (N) concentration (0.317% N) initially increases after addition of below-gap excitation (BGE) light over above-gap excitation (AGE) light and then quenches at higher BGE density and energy, while that of GaAs (e-A°) emission of GaAs layers decreases monotonically. For sample with higher N concentration (1.18% N) both the E {-} band and GaAs (e-A°) emission decreases monotonically with enhancing BGE density and degree of decreasing of PL intensity is higher compared to the low N concentration sample. The quenching of PL intensity indicates the existence of NRR centers in GaAs layers and GaAs:N delta-doped SL region. The recombination models have been proposed for explaining the results from the experiments.
Institute of Electrical and Electronics Engineers Inc., 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/IC4ME247184.2019.9036541
DOI ID：10.1109/IC4ME247184.2019.9036541, SCOPUS ID：85082984670 - Evolution of morphology and crystalline quality of DC-sputtered AlN films with high-temperature annealing
Yosuke Mogami; Shogo Motegi; Atsushi Osawa; Kazuto Osaki; Yukitake Tanioka; Atsushi Maeoka; Masafumi Jo; Noritoshi Maeda; Hiroyuki Yaguchi; Hideki Hirayama
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：58, 号：SC, 2019年06月, ［査読有り］
High-temperature annealing (HTA) is a promising technique to improve the crystalline quality of AlN films. Combining HTA with RF sputtering, Miyake et al. have reported the fabrication of high-quality AlN templates on sapphire [J. Cryst. Growth 456, 155 (2016)], which paves the way to realizing low-cost AlGaN UV optical devices. In terms of AlN growth, DC sputtering is interesting because of its low cost and high throughput. We studied the effect of HTA on the morphology and crystalline quality of DC-sputtered AlN films. As with RF sputtering, HTA substantially improved the crystalline quality of DC-sputtered AlN films. In contrast, hillocks were formed on the surface after HTA, which plausibly stems from the rough surface with spiked structures of the DC-sputtered film. Additional growth of AlN on annealed samples improved the surface morphology and crystalline quality except for the sample containing large hillocks. (C) 2019 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/1347-4065/ab1066
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85070748484&origin=inward
DOI ID：10.7567/1347-4065/ab1066, ISSN：0021-4922, eISSN：1347-4065, ORCID：64953799, SCOPUS ID：85070748484, Web of Science ID：WOS:000474911400036 - Growth temperature dependence of cubic GaN step structures and cubic InN dot arrays grown on MgO (001) vicinal substrates
Kazumasa Okura; Kengo Takamiya; Shuhei Yagi; Hiroyuki Yaguchi
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：58, 号：SC, 2019年06月, ［査読有り］
In this paper, we report on the detailed structural features of step-bunched surface formed on cubic (c-) GaN and self-assembled c-InN dot arrays grown on the c-GaN surface, particularly focusing on the growth temperature dependence. Samples were fabricated on MgO (001) vicinal substrates with off-cut angles of 2.0 degrees and 3.5 degrees toward [110] by RF-MBE. Multisteps and terraces with a certain periodicity in the vicinal direction were observed on c-GaN layers. The average terrace width narrowed with lowering the growth temperature and increasing the substrate off-cut angle. The formation of c-InN dots proceeded in the Stranski-Krastanov growth mode with critical thickness of 0.54-0.66 nm. The c-InN dot exhibited a variety of structural features depending on the growth conditions. Positional dot alignment along the multistep edges of the underlayer was observed under some conditions. The degree of alignment was found to be affected by the terrace width on the c-GaN underlayer. (C) 2019 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/1347-4065/ab106a
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85070734869&origin=inward
DOI ID：10.7567/1347-4065/ab106a, ISSN：0021-4922, eISSN：1347-4065, ORCID：64953806, SCOPUS ID：85070734869, Web of Science ID：WOS:000474911400059 - Solid State Devices and Materials
Takuji Hosoi; Hiroyuki Yaguchi; Hiroyuki Kageshima; Masayuki Chikamatsu; Hirokazu Fujiwara; Mamoru Furuta; Kazuyuki Hirama; Kou Johguchi; Toshiaki Kato; Kenichi Kawaguchi; Akihiko Kikuchi; Kentaro Kinoshita; Hideki Kitada; Masaharu Kobayashi; Rihito Kuroda; Shinichiro Kuroki; Tomoko Matsudai; Takeo Minari; Hiroshi Morioka; Kosuke Nagashio; Kazuyoshi Nakada; Osamu Nakatsuka; Akira Oiwa; Hiroyuki Okada; Takafumi Okuda; Teruo Ono; Toshitsugu Sakamoto; Kenji Shiojima; Mizuki Shirao; Mayumi Takeyama; Tetsu Tanaka; Hirokazu Tatsuoka; Takehiko Tawara; Takeshi Tayagaki; Takashi Tokuda; Kunio Tsuda; Makoto Ueki; Kazuhiko Yamamoto; Wenchang Yeh
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：58, 2019年04月
IOP PUBLISHING LTD, 英語
DOI：https://doi.org/10.7567/1347-4065/ab04f2
DOI ID：10.7567/1347-4065/ab04f2, ISSN：0021-4922, eISSN：1347-4065, Web of Science ID：WOS:000464309900001 - Photoluminescence characterization of nonradiative recombination centers in MOVPE grown GaAs:N delta-doped superlattice structure
Md Dulal Haque; Norihiko Kamata; A. Z. M. Touhidul Islam; Zentaro Honda; Shuhei Yagi; Hiroyuki Yaguchi
OPTICAL MATERIALS, 巻：89, 開始ページ：521, 終了ページ：527, 2019年03月, ［査読有り］
Nonradiative recombination (NRR) centers in GaAs:N delta-doped superlattice (SL) structure grown by metal organic vapor phase epitaxy (MOVPE) are studied by two-wavelength-excited photoluminescence (PL) method. The PL intensity quenching due to the superposition of below-gap excitation (BGE) light at energies of 0.75, 0.80, 0.92, and 0.95 eV and an above-gap excitation (AGE) light either for the GaAs conduction band (1.69 eV) or E_ band excitation (1.45 eV), respectively indicates the existence of NRR centers inside the GaAs:N delta-doped SL and GaAs layers. The AGE density and BGE density dependence of the PL intensity have been studied for both excitation schemes. Recombination model based on two levels has been proposed to interpret the experimental results and energy distribution of NRR centers inside the GaAs:N delta-doped SLs and GaAs layers. The defect-related parameters are estimated systematically by solving the rate equations and fitting the results with the experimental data that give a phenomenological insight into the sample.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.optmat.2019.01.047
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85061552945&origin=inward
DOI ID：10.1016/j.optmat.2019.01.047, ISSN：0925-3467, eISSN：1873-1252, ORCID：64953761, SCOPUS ID：85061552945, Web of Science ID：WOS:000465509800074 - Epitaxial growth of organolead-halide perovskite on rubrene single crystals
Y. Auchi; T. Miyadera; T. Koganezawa; H. Yaguchi; M. Chikamatsu; Y. Yoshida
Extended Abstracts of the 2018 International Conference on Solid State Devices and Materials, 2018年09月, ［査読有り］
The Japan Society of Applied Physics, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.7567/ssdm.2018.f-4-04
DOI ID：10.7567/ssdm.2018.f-4-04 - Effects of solvent vapor annealing on organic photovoltaics with a new type of solution-processable oligothiophene-based electronic donor material
Yuki Akiyama; Hiroaki Tachibana; Reiko Azumi; Tetsuhiko Miyadera; Masayuki Chikamatsu; Tomoyuki Koganezawa; Shuhei Yagi; Hiroyuki Yaguchi
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：57, 号：8, 2018年08月, ［査読有り］
We synthesized a pair of A-D-A-D-A (A = acceptor, D = donor unit) oligomers containing a benzothiadiazole (BT) unit, namely, DRCN5BT-HH and DRCN5BT-TT, which differs in the positions of alkyl side chains. Solution-processed bulk heterojunction solar cells consisting of PC61BM and DRCN5BT-HH gave a high V-oc of 1.10 V and markedly improved power conversion efficiencies up to 3.26% after solvent vapor annealing (SVA). The effects of SVA on the morphology and microstructure of the active layer were investigated by atomic force microscopy (AFM) and grazing-incidence wide angle X-ray scattering (GIWAXS). For DRCN5BT-HH, crystallization, orientation, and molecular ordering were improved, and a fibrillar structure was formed with acicular aggregates of the donor. For DRCN5BT-TT, no marked structural changes were induced by SVA. We found that these morphological and microstructural changes induced by SVA correlate with the differences in the photovoltaic properties of both of the isomers. (C) 2018 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/JJAP.57.08RE09
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85050968954&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85050968954&origin=inward
DOI ID：10.7567/JJAP.57.08RE09, ISSN：0021-4922, eISSN：1347-4065, ORCID：56291723, SCOPUS ID：85050968954, Web of Science ID：WOS:000443891800067 - Biexciton Emission From Single Quantum-Confined Structures in N-Polar (000-1) InGaN/GaN Multiple Quantum Wells
Kengo Takamiya; Shuhei Yagi; Hiroyuki Yaguchi; Hidefumi Akiyama; Kanako Shojiki; Tomoyuki Tanikawa; Ryuji Katayama
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 巻：255, 号：5, 2018年05月, ［査読有り］
We report on the observation of biexciton luminescence from single quantum-confined structures in N-polar InGaN/GaN multiple quantum wells (MQWs) grown on c-plane sapphire by metalorganic vapor phase epitaxy. Sharp emission lines are observed at different positions of the sample by micro-photoluminescence (-PL) mapping. The density of sharp emission lines is approximate to 0.3m(-2), which is comparable with the inversion domain (ID) density found from transmission electron microscope observation, suggesting that the sharp emission lines originate from single quantum-confined structures formed by the combination of quantum well and IDs in N-polar InGaN/GaN MQWs. It is found from the excitation power dependence of the PL intensity of two adjacent sharp lines that the intensity of biexciton luminescence at the lower energy side shows a quadratic dependence on the excitation power while that of exciton luminescence at the higher energy side increased linearly with increasing excitation power. The biexciton binding energy is found to be 0.8meV.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssb.201700454
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85038872540&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85038872540&origin=inward
DOI ID：10.1002/pssb.201700454, ISSN：0370-1972, eISSN：1521-3951, ORCID：50444252, SCOPUS ID：85038872540, Web of Science ID：WOS:000432028400019 - Nonradiative recombination centers in GaAs:N delta-doped superlattice revealed by two-wavelength-excited photoluminescence
Md. Dulal Haque; Norihiko Kamata; Takeshi Fukuda; Zentaro Honda; Shuhei Yagi; Hiroyuki Yaguchi; Yoshitaka Okada
JOURNAL OF APPLIED PHYSICS, 巻：123, 号：16, 2018年04月, ［査読有り］
We use two-wavelength-excited photoluminescence (PL) to investigate nonradiative recombination (NRR) centers in GaAs:N delta-doped superlattice (SL) structures grown by molecular beam epitaxy. The change in photoluminescence (PL) intensity due to the superposition of below-gap excitation at energies of 0.75, 0.80, 0.92, and 0.95 eV and above-gap excitation at energies of 1.69 or 1.45 eV into the GaAs conduction band and the E_ band implies the presence of NRR centers inside the GaAs:N delta-doped SL and/or GaAs layers. The change in PL intensity as a function of the photon number density of below-gap excitation is examined for both bands, which enables us to determine the distribution of NRR centers inside the GaAs:N delta-doped SL and GaAs layers. We propose recombination models to explain the experimental results. Defect-related parameters that give a qualitative insight into the samples are investigated systematically by fitting the rate equations to the experimental data. Published by AIP Publishing.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.5011311
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85045973191&origin=inward
DOI ID：10.1063/1.5011311, ISSN：0021-8979, eISSN：1089-7550, ORCID：48141847, SCOPUS ID：85045973191, Web of Science ID：WOS:000431147200029 - Growth of InGaAs: N delta-doped superlattices for multi-junction solar cells
Shumpei Umeda; Shuhei Yagi; Naoya Miyashita; Yoshitaka Okada; Hiroyuki Yaguchi
2018 IEEE 7TH WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION (WCPEC) (A JOINT CONFERENCE OF 45TH IEEE PVSC, 28TH PVSEC & 34TH EU PVSEC), 開始ページ：1861, 終了ページ：1864, 2018年, ［査読有り］
InGaAs:N delta-doped superlattices (SLs) with a band gap of 1 eV were fabricated by molecular beam epitaxy as a candidate for the subcell material of 4-junction lattice-matched tandem solar cells. The N delta-doping was carried out by suppling N source during the growth interruption and the SL structures were obtained by alternate formation of a N delta-doped layer and an In0.06Ga0.94As spacer layer. It was revealed that excess N supply induces interstitial N incorporation and surface roughness. By adjusting the growth conditions and SL structural parameters, coherent growth of SLs with the band gap of 1 eV was successfully achieved.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/PVSC.2018.8547315
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85059879947&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85059879947&origin=inward
DOI ID：10.1109/PVSC.2018.8547315, ISSN：2159-2330, eISSN：2159-2349, SCOPUS ID：85059879947, Web of Science ID：WOS:000469200401194 - Photoluminescence Characterization of Carrier Recombination Centers in 4H-SiC Substrates by Utilizing below Gap Excitation
Keitaro Kondo; Norihiko Kamata; Hiroyuki Yaguchi; Shuhei Yagi; Takeshi Fukuda; Zentaro Honda
Materials Science Forum, 巻：897, 開始ページ：315, 終了ページ：318, 2017年05月, ［査読有り］
Though the crystal growth technology of SiC is improving steadily, it is still crucial to reduce crystalline defects which act as carrier recombination (CR) centers and deteriorate device performance. We detected CR centers in a p-type 4H-SiC substrate by observing the intensity change of photoluminescence due to the addition of a below-gap excitation (BGE) light of 0.93[eV]. We noticed the temperature and the BGE density dependence of band edge (BE) emission in addition to donor acceptor pair (DAP) emission and discriminated the temperature effect from that of BGE. The BGE density dependence of the PL intensity quenching is different among the BE emission, B0- and C0-lines of the DAP, respectively. It gives us an important clue for understanding CR mechanisms inside the bandgap of SiC.
Trans Tech Publications, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/msf.897.315
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85020048562&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85020048562&origin=inward
DOI ID：10.4028/www.scientific.net/msf.897.315, ISSN：1662-9752, eISSN：1662-9752, ORCID：48141472, SCOPUS ID：85020048562 - Self-organized growth of cubic InN dot arrays on cubic GaN using MgO (001) vicinal substrates
Kenichi Ishii; Shuhei Yagi; Hiroyuki Yaguchi
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 巻：254, 号：2, 2017年02月, ［査読有り］
Cubic zincblende InN (c-InN) nanoscale dot arrays are grown on cubic GaN (c-GaN) by RF-molecular beam epitaxy using MgO (001) vicinal substrates oriented 3.5 degrees toward [110]. The obtained dot arrays have longer ordering length compared with those grown using conventional on-axis (just) substrates. The c-GaN underlayer grown on the vicinal substrate exhibits a single-domain crystalline structure, while that grown on the just substrate is a mixture of two orthogonal crystalline domains. The change in the c-GaN domain structure leads to the enlarged domain size and lower density of domain boundaries on the c-GaN (001) surface in [1-10]. The longer ordering length of the c-InN dot on the vicinal substrates is reflected by the decrease in the c-GaN domain boundary that disrupts the lateral ordering of the dot arrays. Atomic force microscope image of c-InN dots grown on a single-domain c-GaN. The sample was fabricated using a MgO (001) vicinal substrate.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssb.201600542
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85000938311&origin=inward
DOI ID：10.1002/pssb.201600542, ISSN：0370-1972, eISSN：1521-3951, ORCID：48141861, SCOPUS ID：85000938311, Web of Science ID：WOS:000394614300028 - Spectral change of intermediate band luminescence in GaP:N due to below-gap excitation: Discrimination from thermal activation
Kamata, N.; Suetsugu, M.; Haque, D.; Yagi, S.; Yaguchi, H.; Karlsson, F.; Holtz, P.O.
Physica Status Solidi (B) Basic Research, 巻：254, 号：2, 2017年, ［査読有り］
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim As an intermediate band (IB) originating from discrete nitrogen (N) levels is formed in GaP:N with increasing N concentration, GaP1−xNx alloy is considered to be a promising candidate for IB-type solar cells. We studied the IB luminescence of a GaP1−xNx with 0.56% N and detected carrier recombination (CR) levels by superposing a below-gap excitation (BGE) light of 1.17 eV. We resolved a high-energy component of 2.15 eV in the IB luminescence, Ihigh, from total luminescence intensity Iall. With increasing the BGE density at fixed temperature of 5 K, the amount of decrease in Ihigh was distinctly smaller than that of simple temperature rise without the BGE at the same Iall value. We conclude that the observed intensity change of the IB luminescence due to the BGE comes not from thermal activation, but from optical excitation among the IB, conduction band, and CR levels in GaP1−xNx. It is of primal importance to understand CR levels toward determining their origins and eliminating them for realization of efficient IB-type solar cells.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssb.201600566
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85003749566&origin=inward
DOI ID：10.1002/pssb.201600566, ISSN：0370-1972, eISSN：1521-3951, ORCID：48141829, SCOPUS ID：85003749566, Web of Science ID：WOS:000394614300035 - Growth of InN/GaN dots on 4H-SiC(0001) 4° off vicinal substrates by molecular beam epitaxy
Shuhei Yagi; Hiroyuki Yaguchi; Keisuke Matsuoka
Journal of Crystal Growth, 巻：477, 開始ページ：201, 終了ページ：206, 2017年, ［査読有り］
We have fabricated self-assembled InN dots on GaN using 4H-SiC(0001) vicinal substrates (4 degrees off toward [11-20]). The size and density of InN dots were well controlled by changing the deposition amount and the growth temperature of InN. Atomic force microscope (AFM) observation revealed that the critical thickness of InN for 2D-3D transition was between 0.8 and 1.0 nm. In addition, it was found that the InN dots were preferentially formed at the multistep edges on GaN. Therefore, the preparation of periodic multistep structures on GaN is considered to be an effective way to obtain highly ordered self-assembled InN dot arrays. (C) 2017 Elsevier B.V. All rights reserved.
Elsevier {BV}, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/J.JCRYSGRO.2017.05.021
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85020105871&origin=inward
DOI ID：10.1016/J.JCRYSGRO.2017.05.021, ISSN：0022-0248, eISSN：1873-5002, ORCID：56291782, SCOPUS ID：85020105871, Web of Science ID：WOS:000413646100043 - Self-Organized Growth of Cubic InN Dot Arrays on MgO (001) Vicinal Substrates
Kenichi Ishii; Shuhei Yagi; Hiroyuki Yaguchi
2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS), 2016年, ［査読有り］
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/ICIPRM.2016.7528673
DOI ID：10.1109/ICIPRM.2016.7528673, ORCID：56291759, Web of Science ID：WOS:000392285400156 - Optical Characterization of Carrier Recombination Processes in GaPN by Two-Wavelength Excited Photoluminescence
Makiko Suetsugu; Norihiko Kamata; Shuhei Yagi; Hiroyuki Yaguchi; Takeshi Fukuda; Fredrik Karlsson; Per-Olof Holts
2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS), 2016年, ［査読有り］
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/ICIPRM.2016.7528672
DOI ID：10.1109/ICIPRM.2016.7528672, ORCID：56291722, Web of Science ID：WOS:000392285400155 - Two-Wavelength Excited Photoluminescence in 4H-SiC Substrate -Dependence on BGE Power Density-
Keitaro Kondo; Norihiko Kamata; Shuhei Yagi; Hiroyuki Yaguchi; Takeshi Fukuda; Zentaro Honda
2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS), 2016年, ［査読有り］
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/ICIPRM.2016.7528594
DOI ID：10.1109/ICIPRM.2016.7528594, ORCID：56291772, Web of Science ID：WOS:000392285400077 - Molecular beam epitaxial growth of intermediate-band materials based on GaAs: N delta-doped superlattices
Tomoya Suzuki; Kazuki Osada; Shuhei Yagi; Shunya Naitoh; Yasushi Shoji; Yasuto Hijikata; Yoshitaka Okada; Hiroyuki Yaguchi
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：54, 号：8, 開始ページ：08KA07, 2015年08月, ［査読有り］
We fabricated GaAs: N delta-doped superlattices (SLs) by molecular beam epitaxy and investigated their potential as an intermediate-band photoabsorber in high-efficiency solar cells. The N area concentration in a N delta-doped layer was well controlled by adjusting the fabrication conditions, and the SLs with the average N composition of up to 1.5% were obtained. The SL minibands related to the N-induced E+ and E- conduction subbands were formed with well-separated bottom energies of up to 0.4 eV, indicating the suitability of this material system for use in intermediate-band solar cells. A two-step photoabsorption process in a solar cell with the SL absorber was successfully demonstrated through external quantum efficiency measurements under additional infrared illumination at room temperature. (C) 2015 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/JJAP.54.08KA07
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84938504709&origin=inward
DOI ID：10.7567/JJAP.54.08KA07, ISSN：0021-4922, eISSN：1347-4065, ORCID：64953767, SCOPUS ID：84938504709, Web of Science ID：WOS:000358662900008 - Control of intermediate-band configuration in GaAs: N delta-doped superlattice
Kazuki Osada; Tomoya Suzuki; Shuhei Yagi; Shunya Naitoh; Yasushi Shoji; Yasuto Hijikata; Yoshitaka Okada; Hiroyuki Yaguchi
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：54, 号：8, 開始ページ：08KA04, 2015年08月, ［査読有り］
GaAs: N delta-doped superlattices (SLs) consisting of alternating layers of undoped and N delta-doped GaAs were fabricated by molecular beam epitaxy (MBE) as possible candidates for the light-absorbing material of intermediate-band solar cells (IBSCs). Since the energy gaps in IBSCs need to be adjusted to optimum values to achieve sufficiently high conversion efficiency, it is important to control precisely the band configuration of intermediate-band (IB) materials. In this study, we demonstrated the control of the IB energy configuration in GaAs: N delta-doped SLs by changing their structural parameters. Optical transitions due to the SL minibands related to the N-induced conduction subbands E+ and E- were clearly observed and the transition energies depended systematically on the N area density and period length of the SLs. Conversion efficiency calculations based on the detailed balance model indicated that IBSCs with an efficiency of nearly 60% are achievable by using the fabricated GaAs: N delta-doped SLs. (C) 2015 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/JJAP.54.08KA04
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84938516127&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84938516127&origin=inward
DOI ID：10.7567/JJAP.54.08KA04, ISSN：0021-4922, eISSN：1347-4065, ORCID：56291671, SCOPUS ID：84938516127, Web of Science ID：WOS:000358662900005 - Growth temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy
Ri Guo Jin; Shuhei Yagi; Yasuto Hijikata; Hiroyuki Yaguchi
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：54, 号：5, 開始ページ：051201, 2015年05月, ［査読有り］
We have quantitatively studied the temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy using secondary ion mass spectroscopy. It was found that a significant number of Er atoms segregate to the growing surface at temperatures of 400 degrees C and above and that the segregation decay length is approximately 0.5 mu m at 500 degrees C, indicating that the incorporation ratio of Er atoms into GaAs is less than 10(-3). In contrast to the growth at higher temperatures, GaAs overlayer growth at a temperature as low as 300 degrees C is effective in suppressing the surface segregation of Er and obtaining delta-doped structures. (C) 2015 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/JJAP.54.051201
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84983072013&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84983072013&origin=inward
DOI ID：10.7567/JJAP.54.051201, ISSN：0021-4922, eISSN：1347-4065, ORCID：56291658, SCOPUS ID：84983072013, Web of Science ID：WOS:000354980300009, 共同研究・競争的資金等ID：11611368 - Differences in SiC thermal oxidation process between crystalline surface orientations observed by in-situ spectroscopic ellipsometry
Daisuke Goto; Yasuto Hijikata; Shuhei Yagi; Hiroyuki Yaguchi
JOURNAL OF APPLIED PHYSICS, 巻：117, 号：9, 開始ページ：095306, 2015年03月, ［査読有り］
For a better understanding of the SiC oxidation mechanism, we investigated differences in the oxidation process for surfaces with different crystal orientations. Real-time observations of oxidation processes for (0001) Si-face, (11 (2) over bar0) a-face, and (000 (1) over bar) C-face substrates at various oxidation temperatures were performed using in-situ spectroscopic ellipsometry. Massoud's empirical equation, which is composed of the classical Deal-Grove equation added by an exponential term, was applied to the observed growth rates and the oxidation rate parameters were extracted by curve fitting. The SiC oxidation mechanism is discussed in terms of the oxidation temperature dependence and surface orientation dependence of the oxidation rate parameters. (C) 2015 AIP Publishing LLC.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.4914050
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84924310120&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84924310120&origin=inward
DOI ID：10.1063/1.4914050, ISSN：0021-8979, eISSN：1089-7550, ORCID：56291706, SCOPUS ID：84924310120, Web of Science ID：WOS:000351134400041 - Photoluminescence Study of Oxidation-Induced Stacking Faults in 4H-SiC Epilayers
Miyano, Y; Yagi, S; Hijikata, Y; Yaguchi, H
Materials Science Forum, 巻：821-823, 開始ページ：327, 終了ページ：330, 2015年, ［査読有り］
Trans Tech Publications, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.821-823.327
DOI ID：10.4028/www.scientific.net/MSF.821-823.327, ISSN：1662-9752, ORCID：50444258 - Surface orientation dependence of SiC oxidation process studied by in-situ spectroscopic ellipsometry
Goto, D.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
Materials Science Forum, 巻：821-823, 開始ページ：371, 終了ページ：374, 2015年, ［査読有り］
© (2014) Trans Tech Publications, Switzerland. We performed real-time observations of SiC oxidation at various temperatures by in-situ spectroscopic ellipsometry using a Si-face, an a-face and a C-face substrates. We calculated oxide growth rates based on “Si-C emission model,” taking into account the emission of interfacial Si and C atoms from the SiC–SiO2 interface. The calculated values well reproduced the oxide thickness dependence of oxide growth rates. We discussed the SiC oxidation mechanism using the parameters deduced from the calculations.
Materials Science Forum, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.821-823.371
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84950341587&origin=inward
DOI ID：10.4028/www.scientific.net/MSF.821-823.371, ISSN：0255-5476, eISSN：1662-9752, ORCID：64953813, SCOPUS ID：84950341587 - Microstructures of InN film on 4H-SiC (0001) substrate grown by RF-MBE
P. Limsuwan; H. Yaguchi; M. Orihara; S. Sanorpim; P. Jantawongrit
Journal of Semiconductors, 巻：36, 号：8, 2015年, ［査読有り］
© 2015 Chinese Institute of Electronics. InN film was grown on 4H-SiC (0001) substrate by RF plasma-assisted molecular beam epitaxy (RF-MBE). Prior to the growth of InN film, an InN buffer layer with a thickness of ∼5.5 nm was grown on the substrate. Surface morphology, microstructure and structural quality of InN film were investigated. Micro-structural defects, such as stacking faults and anti-phase domain in InN film were carefully investigated using transmission electron microscopy (TEM). The results show that a high density of line contrasts, parallel to the growth direction (c-axis), was clearly observed in the grown InN film. Dark field TEM images recorded with diffraction vectors and g = 0002 revealed that such line contrasts evolved from a coalescence of the adjacent misoriented islands during the initial stage of the InN nucleation on the substrate surface. This InN nucleation also led to a generation of anti-phase domains.
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1088/1674-4926/36/8/083002
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84940094786&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84940094786&origin=inward
DOI ID：10.1088/1674-4926/36/8/083002, ISSN：1674-4926, ORCID：56291719, SCOPUS ID：84940094786, Web of Science ID：WOS:000218443900007 - Photoluminescence study of oxidation-induced faults in 4H-SiC epilayers
Miyano, Y.; Asafuji, R.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
AIP Advances, 巻：5, 号：12, 開始ページ：127116, 2015年, ［査読有り］
We investigated the effect of thermal oxidation on crystalline faults in 4H-SiC epilayers using photoluminescence imaging. We found that a comb-shaped dislocation array was deformed by thermal oxidation. We also found that line-shaped faults perpendicular to the off-cut direction were formed during oxidation and were stretched and increased with the oxidation time. Since these line-shaped faults were peculiar to the oxidation and stretched/increased with the oxide growth, they were identified as oxidation-induced stacking faults as seen in Si oxidation. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.4938126
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84952672264&origin=inward
DOI ID：10.1063/1.4938126, ISSN：2158-3226, eISSN：2158-3226, ORCID：64953793, SCOPUS ID：84952672264, Web of Science ID：WOS:000367596300016 - Enhanced optical absorption due to E+-related band transition in GaAs:N delta-doped superlattices
Shuhei Yagi; Shunsuke Noguchi; Yasuto Hijikata; Shigeyuki Kuboya; Kentaro Onabe; Yoshitaka Okada; Hiroyuki Yaguchi
APPLIED PHYSICS EXPRESS, 巻：7, 号：10, 2014年10月, ［査読有り］
The photoabsorption characteristics of GaAs:N delta-doped superlattices (SLs) are investigated. Periodic insertion of N delta-doped induces the formation of conduction subbands E+ and E-, and each conduction subband forms SL minibands with the GaAs between the delta-doped layers. In addition to an optical absorption related to the E- band, an abrupt absorption edge originating transition between the valence band and an E+-related miniband is observed at 1.6 eV in a photoluminescence excitation indicating that GaAs:N delta-doped SLs are promising candidates for the absorber of intermediate-band solar cells. (C) 2014 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/APEX.7.102301
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84988891884&origin=inward
DOI ID：10.7567/APEX.7.102301, ISSN：1882-0778, eISSN：1882-0786, ORCID：48141835, SCOPUS ID：84988891884, Web of Science ID：WOS:000344439300007 - Photoreflectance study of the temperature dependence of excitonic transitions in dilute GaAsN alloys
Wataru Okubo; Shuhei Yagi; Yasuto Hijikata; Kentaro Onabe; Hiroyuki Yaguchi
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, 巻：211, 号：4, 開始ページ：752, 終了ページ：755, 2014年04月, ［査読有り］
We have studied the temperature dependence of optical transitions in dilute GaAsN alloys using photoreflectance (PR). A delocalized-state transition is clearly observed in PR spectra while several localized-state emission lines due to isoelectronic centers appear in photoluminescence spectra. The energy of optical transitions observed in PR spectra is in agreement with the excitonic transition energy in photoluminescence excitation spectra, clearly showing that the optical transitions in PR spectra are excitonic transitions. We analyzed the temperature dependence of the excitonic transition energies using the Bose-Einstein statistical expression, and found that even dilute alloys follow the same trend as GaAsN alloys with higher nitrogen concentrations. We discuss the coexistence of localized and delocalized states in dilute GaAsN alloys in terms of the random distribution of N atoms.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssa.201300462
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84897986009&origin=inward
DOI ID：10.1002/pssa.201300462, ISSN：1862-6300, eISSN：1862-6319, ORCID：56291616, SCOPUS ID：84897986009, Web of Science ID：WOS:000333911800006, 共同研究・競争的資金等ID：11611368 - Si emission into the oxide layer during oxidation of silicon carbide
Yurie Akasaka; Yasuto Hijikata; Shuhei Yagi; HIROYUKI YAGUCHI
Materials Science Forum, 巻：778-780, 開始ページ：553, 終了ページ：556, 2014年, ［査読有り］
Trans Tech Publications, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/WWW.SCIENTIFIC.NET/MSF.778-780.553
DOI ID：10.4028/WWW.SCIENTIFIC.NET/MSF.778-780.553, ISSN：1662-9752, ORCID：56291610, Web of Science ID：WOS:000336634100130 - First-principles study on the conduction band electron states of GaAsN alloys
Kei Sakamoto; Hiroyuki Yaguchi
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 11, NO 3-4, 巻：11, 号：3-4, 開始ページ：911, 終了ページ：913, 2014年, ［査読有り］
We have analyzed the electronic states of the lowest conduction band of GaAsN alloys based on the first-principles calculation. In order to study the nitrogen concentration dependence of the electron effective mass, we calculated the electronic structure of GaAsN alloys using a full-potential density functional theory program. The calculated effective mass of GaAsN with a dilute nitrogen concentration is about twice as heavy as that of GaAs. In addition, the effective mass is found to decrease with increasing nitrogen concentration although it is always heavier than that of GaAs. In addition, we calculated the density of states of GaAsN to examine what the cause of the decrease in the effective mass is. Our calculations suggest the discontinuity of the physical property from GaAs to GaAsN and provide an important insight into the formation of the conduction band states of GaAsN alloys. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.201300531
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84898548200&origin=inward
DOI ID：10.1002/pssc.201300531, ISSN：1862-6351, eISSN：1610-1642, ORCID：64953783, SCOPUS ID：84898548200, Web of Science ID：WOS:000346071300134, 共同研究・競争的資金等ID：11611368 - Conversion Efficiency of Intermediate Band Solar Cells with GaAs:N delta-Doped Superlattices
Shuhei Yagi; Shunsuke Noguchi; Yasuto Hijikata; Shigeyuki Kuboya; Kentaro Onabe; Hiroyuki Yaguchi
JAPANESE JOURNAL OF APPLIED PHYSICS, 巻：52, 号：10, 2013年10月, ［査読有り］
The performance of intermediate band solar cells using a GaAs:N delta-doped superlattice (SL) as the optical absorber is analyzed. In GaAs: N delta-doped SLs, both of the E+ and E- bands formed around the N delta-doped layers form SL potentials with the conduction band of the spacer GaAs layers, resulting in the formation of multiple minibands. The conversion efficiency limits of the solar cells are calculated using the detailed balance model based on intermediate band structures composed of the valence band and two minibands formed respectively in the E-- and E+-related SL potentials. A high efficiency of 62.6% for full concentration is expected by properly adjusting the structural parameters of the SL. Alloying other elements such as In to a GaAs:N delta-doped SL is a possible way to further facilitate the development of intermediate band materials for high-efficiency solar cells. (C) 2013 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/JJAP.52.102302
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84887232116&origin=inward
DOI ID：10.7567/JJAP.52.102302, ISSN：0021-4922, eISSN：1347-4065, ORCID：30384763, SCOPUS ID：84887232116, Web of Science ID：WOS:000325209000024 - Analysis of Electronic Structures of Nitrogen delta-Doped GaAs Superlattices for High Efficiency Intermediate Band Solar Cells
Shunsuke Noguchi; Shuhei Yagi; Daisuke Sato; Yasuto Hijikata; Kentaro Onabe; Shigeyuki Kuboya; Hiroyuki Yaguchi
IEEE JOURNAL OF PHOTOVOLTAICS, 巻：3, 号：4, 開始ページ：1287, 終了ページ：1291, 2013年10月, ［査読有り］
Nitrogen delta-doped GaAs superlattices (SLs) were fabricated, and their energy structures were investigated. A number of strong transition signals are observed in photoreflectane (PR) spectra in an energy range from 1.54 to 1.78 eV for SL samples in which any transitions are not observed in uniformly nitrogen-doped GaAsN with comparable nitrogen content. Both of the E+ and E- bands formed around the nitrogen delta-doped layers compose SL potentials with the conduction band of the spacer GaAs layers, resulting in the formation of multiple minibands. The energy range of the SL minibands well explains the observed transition energies in the PR spectra. The PR signal intensity ratios of the E+-related transitions to the E--related transitions for the SLs are notably large compared with those usually observed for conventional GaAsN alloys. This enhancement of electron transition associated with the E+-related bands should be advantageous as intermediate band material. Therefore, nitrogen delta-doped GaAs SLs are expected to be an excellent alternative to uniformly doped GaAsN alloys for the use in intermediate band solar cells.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1109/JPHOTOV.2013.2271978
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84884672481&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84884672481&origin=inward
DOI ID：10.1109/JPHOTOV.2013.2271978, ISSN：2156-3381, eISSN：2156-3403, ORCID：30384761, SCOPUS ID：84884672481, Web of Science ID：WOS:000324881400023 - Direct Evidence of Carrier Excitation from Intermediate Band States in GaPN by Two-Wavelength Excited Photoluminescence
Abu Zafor Muhammad Touhidul Islam; Tsukasa Hanaoka; Kentaro Onabe; Shuhei Yagi; Norihiko Kamata; Hiroyuki Yaguchi
APPLIED PHYSICS EXPRESS, 巻：6, 号：9, 2013年09月, ［査読有り］
An investigation of two-wavelength excited photoluminescence on GaPN alloys containing 0.56% nitrogen was conducted to directly excite intermediate band (IB) states and monitor its impact on photoluminescence (PL) properties. The 22 K PL due to above-gap excitation (AGE) showed broad peak emission induced by the IB states. With the use of below-gap excitation (BGE) of 1.17 eV energy in addition to the AGE, the PL peak intensity was found to decrease linearly with increasing the BGE power, which suggests that the BGE perturbs the bound exciton recombination mechanism by exciting electrons from the IB states through the dissociation of excitons. (c) 2013 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/APEX.6.092401
DOI ID：10.7567/APEX.6.092401, ISSN：1882-0778, eISSN：1882-0786, Web of Science ID：WOS:000324494100020 - RF-MBE growth of cubic InN nano-scale dots on cubic GaN
Junichiro Suzuki; Misao Orihara; Shuhei Yagi; Yasuto Hijikata; Hiroyuki Yaguchi
JOURNAL OF CRYSTAL GROWTH, 巻：378, 開始ページ：454, 終了ページ：458, 2013年09月, ［査読有り］
This paper reports the first successful growth and structural control of cubic InN (c-InN) nano-scale dots. The samples were grown on MgO (0 0 1) substrates by RF-N-2 plasma molecular beam epitaxy (RF-MBE). Cubic GaN (c-GaN) underlayers with a thickness of 500 nm were grown on the substrates followed by the growth of a few nm-thick InN under various conditions. The formation of InN dots aligned along the < 1 1 0 > directions were confirmed by atomic force microscopy (AFM). X-ray diffraction (XRD) measurements suggested the cubic zincblende lattice structure of the obtained InN dots. The area density and size of c-InN dots were well controlled by adjusting the growth conditions such as the substrate temperature and the In flux, and a very high dot density of 2.2 x 10(11) cm(-2) was successfully obtained at a growth temperature of 470 degrees C and an In flux of 7.0 x 10(-5) Pa. (c) 2013 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.050
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84885434999&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84885434999&origin=inward
DOI ID：10.1016/j.jcrysgro.2012.12.050, ISSN：0022-0248, eISSN：1873-5002, ORCID：30384771, SCOPUS ID：84885434999, Web of Science ID：WOS:000323355900113 - Molecular beam epitaxy of ErGaAs alloys on GaAs (001) substrates
Ri Guo Jin; Shuhei Yagi; Yasuto Hijikata; Shigeyuki Kuboya; Kentaro Onabe; Ryuji Katayama; Hiroyuki Yaguchi
JOURNAL OF CRYSTAL GROWTH, 巻：378, 開始ページ：85, 終了ページ：87, 2013年09月, ［査読有り］
We have successfully grown high crystalline quality ErGaAs alloy layers by solid-source molecular beam epitaxy. The X-ray diffraction (XRD) peak of ErGaAs alloys was found to shift systematically from the GaAs peak with increasing Er concentration up to 3.7%. XRD (1 1 5) reciprocal space map measurements revealed that the ErGaAs epitaxial layer is coherently grown on GaAs. We found from XRD results that ErGaAs alloys with low Er concentrations tend to crystallize in the zincblende structure. (c) 2012 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.043
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84885427998&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84885427998&origin=inward
DOI ID：10.1016/j.jcrysgro.2012.12.043, ISSN：0022-0248, ORCID：30384766, SCOPUS ID：84885427998, Web of Science ID：WOS:000323355900023 - Direct Evidence of Carrier Excitation from Intermediate Band States in GaPN by Two-Wavelength Excited Photoluminescence
Islam A. M. T; Hanaoka T; Onabe K; Yagi S; Kamata N; Yaguchi H
Applied Physics Express, 巻：6, 号：9, 開始ページ：3, 2013年09月, ［査読有り］
An investigation of two-wavelength excited photoluminescence on GaPN alloys containing 0.56% nitrogen was conducted to directly excite intermediate band (IB) states and monitor its impact on photoluminescence (PL) properties. The 22 K PL due to above-gap excitation (AGE) showed broad peak emission induced by the IB states. With the use of below-gap excitation (BGE) of 1.17 eV energy in addition to the AGE, the PL peak intensity was found to decrease linearly with increasing the BGE power, which suggests that the BGE perturbs the bound exciton recombination mechanism by exciting electrons from the IB states through the dissociation of excitons. © 2013 The Japan Society of Applied Physics.
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/APEX.6.092401
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84883664354&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84883664354&origin=inward
DOI ID：10.7567/APEX.6.092401, ISSN：1882-0778, eISSN：1882-0786, ORCID：30384764, SCOPUS ID：84883664354, Web of Science ID：WOS:000324494100020 - Observation of optical spin injection into Ge-based structures at room temperature
Yuhsuke Yasutake; Shuhei Hayashi; Hiroyuki Yaguchi; Susumu Fukatsu
APPLIED PHYSICS LETTERS, 巻：102, 号：24, 2013年06月, ［査読有り］
Non-zero spin polarization induced by optical orientation was clearly observed at room temperature in a Ge/Ge0.8Si0.2 quantum well grown on Ge and a Ge layer grown on Si by molecular beam epitaxy, whereas it was absent in bulk Ge. This occurred because indirect-gap photoluminescence (PL), which can obscure the spin-polarization information carried by the direct-gap PL, was quenched by unintentional growth-related defects in the epitaxial layers. Such interpretation was confirmed by applying time gating that effectively removed the indirect-gap PL characterized by a slower rise time, which allowed us to demonstrate the existence of room-temperature spin polarization in bulk Ge. (C) 2013 AIP Publishing LLC.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.4811495
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84879811389&origin=inward
DOI ID：10.1063/1.4811495, ISSN：0003-6951, ORCID：30384767, SCOPUS ID：84879811389, Web of Science ID：WOS:000320962400045 - Optical Properties and Carrier Dynamics in Asymmetric Coupled InGaN Multiple Quantum Wells
Weng G. E; Zhang B. P; Liang M. M; Lv X. Q; Zhang J. Y; Ying L. Y; Qiu Z. R; Yaguchi H; Kuboya S; Onabe K; Chen S. Q; Akiyama H
Functional Materials Letters, 巻：6, 号：2, 開始ページ：5, 2013年04月, ［査読有り］
Optical properties and carrier dynamics of InGaN/GaN asymmetric coupled quantum wells (ACQWs) are studied by excitation-power-dependent photoluminescence (PL), photoreflectance (PR) and time-resolved PL (TRPL) experiments. Under weak excitations, only the emission from the widest well is observed due to the tunneling from narrower to wider wells. Under strong excitations, the carrier distribution becomes more uniform and an enhanced emission from the mid well (2.5 nm well) is observed. Dependence of the PL intensity on excitation power is well explained by a rate equation model. The energy levels in the ACQW structure are clearly revealed by PR measurements and are in good agreement with calculations. Our results indicate that the enhanced emission from the mid well is ascribed to «reverse tunneling» from 3.0 to 2.5 nm well, which is confirmed by TRPL experiments. © 2013 World Scientific Publishing Company.
WORLD SCIENTIFIC PUBL CO PTE LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1142/S1793604713500215
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84876756647&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84876756647&origin=inward
DOI ID：10.1142/S1793604713500215, ISSN：1793-6047, eISSN：1793-7213, ORCID：30384769, SCOPUS ID：84876756647, Web of Science ID：WOS:000319747700012 - Stacked structure of self-organized cubic InN nano-dots grown by molecular beam epitaxy
Shuhei Yagi; Junichiro Suzuki; Misao Orihara; Yasuto Hijikata; Hiroyuki Yaguchi
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 10, NO 11, 巻：10, 号：11, 開始ページ：1545, 終了ページ：1548, 2013年, ［査読有り］
A two-stacked cubic (c-) InN/c-GaN nano-scale dot structure is fabricated on a MgO(001) substrate by RF-N-2 molecular beam epitaxy and its microstructures are investigated by scanning transmission electron microscopy (STEM). The cubic lattice structure of InN dots is verified by STEM observations. It is implied that c-InN dots formed on a smooth c-GaN surface have the {111} facets. The c-GaN cap layer has an uneven surface, which reflects the shape of the c-InN dots embedded beneath the cap layer. InN selectively deposits in concave regions on the c-GaN cap layer, which appear above in-between positions of embedded dots. Thus, stacked c-InN/c-GaN dots do not tend to align vertically. These results open the possibility for multi-stacking structures of c-InN dots and their application to high-performance optoelectronic devices based on the nitride semiconductors. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.201300275
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84887619549&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84887619549&origin=inward
DOI ID：10.1002/pssc.201300275, ISSN：1862-6351, eISSN：1610-1642, ORCID：30384772, SCOPUS ID：84887619549, Web of Science ID：WOS:000334583400049 - RF-MBE growth of cubic AlN on MgO (001) substrates via 2-step c-GaN buffer layer
Kakuda M; Morikawa S; Kuboya S; Katayama R; Yaguchi H; Onabe K
Journal of Crystal Growth, 巻：378, 開始ページ：307, 終了ページ：309, 2013年, ［査読有り］
We fabricated cubic AlN (c-AlN) films on MgO (001) substrates via 2-step c-GaN buffer layer by radio-frequency-plasma-assisted molecular beam epitaxy (RF-MBE). The effect of low temperature c-GaN buffer layer on the surface flatness and crystal quality of c-AlN was investigated by AFM and XRD reciprocal space mapping analysis. We examined optical properties of the c-AlN film by spectroscopic ellipsometry. The absorption edge by the direct transition of the c-AlN film was 5.95 eV caused by the hexagonal phase incorporation. © 2013 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.120
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84885422048&origin=inward
DOI ID：10.1016/j.jcrysgro.2012.12.120, ISSN：0022-0248, ORCID：30384770, SCOPUS ID：84885422048, Web of Science ID：WOS:000323355900078 - Optical Absorption by E+ Miniband of GaAs:N delta-Doped Superlattices
Shuhei Yagi; Shunsuke Noguchi; Yasuto Hijikata; Shigeyuki Kuboya; Kentaro Onabe; Yoshitaka Okada; Hiroyuki Yaguchi
2013 IEEE 39TH PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC), 開始ページ：2490, 終了ページ：2493, 2013年, ［査読有り］
The optical properties of GaAs:N delta-doped superlattices (SLs) are investigated by photoreflectance (PR), photo luminescence (PL) and photoluminescence excitation (PLE) spectroscopy. A direct evidence of the optical absorption due to an E, related band of a GaAs:N delta-doped SLs is indicated as a clear absorption edge at 1.6 eV by PLE. AlGaAs layers fabricated on the both sides of the SL region exclude the effect of GaAs absorption on the PLE spectrum, resulting in the successful detection of the absorption property of the SL. In addition, some preliminary characterization of a solar cell using a GaAs:N delta-doped SL is shown. The photocarrier generation originating from SL miniband absorption is confirmed by quantum efficiency measurements.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/PVSC.2013.6744981
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84896474240&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84896474240&origin=inward
DOI ID：10.1109/PVSC.2013.6744981, ISSN：0160-8371, ORCID：30384768, SCOPUS ID：84896474240, Web of Science ID：WOS:000340054100565 - Model calculations of SiC oxide growth rates at sub-atmospheric pressures using the Si and C emission model
Yasuto Hijikata; Shuhei Yagi; Hiroyuki Yaguchi; Sadafumi Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2012, 巻：740-742, 開始ページ：833, 終了ページ：+, 2013年, ［査読有り］
We found that the 'Si and C emission model' that we proposed as an oxidation model of SiC could not reproduce the initial oxide growth rates of SiC at sub-atmospheric pressures. The comparison between calculated and observed growth rates suggests that the oxide growth on the oxide surface is enhanced in the initial oxidation stage and thus our oxidation model is inaccurate in the description of the initial surface oxidation. Accordingly, we have reconsidered the parameters on surface oxidation and, as a result, found that a much enlarged oxygen concentration on the oxide surface is necessary for solving the discrepancy between calculated and observed growth rates.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.740-742.833
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84874076989&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84874076989&origin=inward
DOI ID：10.4028/www.scientific.net/MSF.740-742.833, ISSN：0255-5476, ORCID：30384765, SCOPUS ID：84874076989, Web of Science ID：WOS:000319785500198 - Biexciton emission from single isoelectronic traps formed by nitrogen-nitrogen pairs in GaAs
Kengo Takamiya; Toshiyuki Fukushima; Shuhei Yagi; Yasuto Hijikata; Toshimitsu Mochizuki; Masahiro Yoshita; Hidefumi Akiyama; Shigeyuki Kuboya; Kentaro Onabe; Ryuji Katayama; Hiroyuki Yaguchi
AIP Conference Proceedings, 巻：1566, 開始ページ：538, 終了ページ：+, 2013年
We have studied photoluminescence (PL) from individual isoelectronic traps formed by nitrogen-nitrogen (NN) pairs in GaAs. Sharp emission lines due to exciton and biexciton were observed from individual isoelectronic traps in nitrogen atomic-layer doped (ALD) GaAs. The binding energy of biexciton bound to individual isoelectronic traps was approximately 8 meV. Both the exciton and biexciton luminescence lines show completely random polarization and no fine-structure splitting. These results are desirable to the application to the quantum cryptography used in the field of quantum information technology.
AIP, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1063/1.4848523
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84907305933&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84907305933&origin=inward
DOI ID：10.1063/1.4848523, ISSN：0094-243X, eISSN：1551-7616, ORCID：30384762, SCOPUS ID：84907305933, Web of Science ID：WOS:000331793000268, 共同研究・競争的資金等ID：11611368 - Biexciton Luminescence from Individual Isoelectronic Traps in Nitrogen delta-Doped GaAs
Kengo Takamiya; Toshiyuki Fukushima; Shuhei Yagi; Yasuto Hijikata; Toshimitsu Mochizuki; Masahiro Yoshita; Hidefumi Akiyama; Shigeyuki Kuboya; Kentaro Onabe; Ryuji Katayama; Hiroyuki Yaguchi
APPLIED PHYSICS EXPRESS, 巻：5, 号：11, 開始ページ：3, 2012年11月, ［査読有り］
We report on the observation of biexciton luminescence from single isoelectronic traps formed by nitrogen-nitrogen pairs in nitrogen delta-doped GaAs. The biexciton luminescence intensity showed a quadratic dependence on the excitation power while the exciton luminescence intensity increased linearly with increasing excitation power. The biexciton binding energy was found to be 8 meV, which is considerably larger than that reported for single InAs quantum dots in GaAs. We have also found that both the biexciton and exciton emission lines show completely unpolarized and no fine-structure splitting. This is suitable for the application to polarization-entangled photon pairs. (C) 2012 The Japan Society of Applied Physics
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/APEX.5.111201
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84869186070&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84869186070&origin=inward
DOI ID：10.1143/APEX.5.111201, ISSN：1882-0778, eISSN：1882-0786, ORCID：30384774, SCOPUS ID：84869186070, Web of Science ID：WOS:000310867800003, 共同研究・競争的資金等ID：11611368 - Oxygen partial pressure dependence of the SiC oxidation process studied by in-situ spectroscopic ellipsometry
Keiko Kouda; Yasuto Hijikata; Shuhei Yagi; Hiroyuki Yaguchi; Sadafumi Yoshida
JOURNAL OF APPLIED PHYSICS, 巻：112, 号：2, 開始ページ：6, 2012年07月, ［査読有り］
The oxygen partial pressure dependence of the Silicon carbide (SiC) oxidation process was investigated using in-situ spectroscopic ellipsometry at oxygen partial pressures between 1 and 0.02 atm for 4H-SiC (0001) Si-and (000-1) C-faces. Analyses of the interface structure between the oxide and SiC indicate that the interface layer has a modified SiC-like structure around 1 nm thick accompanied by oxide growth; the structure and thickness do not change after an oxide growth of about 7 nm. The oxide thickness dependence of the growth rate at sub-atmospheric oxygen pressures is similar to that at 1 atm pressure, that is, just after oxidation starts, the growth rate rapidly decreases as the oxidation proceeds. After an oxide growth of about 7 nm thick, the deceleration of the growth rate suddenly changes to a gentle slope. The thickness at which deceleration changes depends slightly on both the oxygen partial pressure and surface polarity of the SiC substrate. The origins of these two deceleration stages, i.e., rapid and gentle decelerations, are discussed from their pressure dependencies based on the SiC oxidation model taking into account the interfacial emission of Si and C atoms. The formation and structures of the interface layers are also discussed in relation to the oxidation mechanisms. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4736801]
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.4736801
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84865484968&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84865484968&origin=inward
DOI ID：10.1063/1.4736801, ISSN：0021-8979, eISSN：1089-7550, ORCID：30384777, SCOPUS ID：84865484968, Web of Science ID：WOS:000308424500114 - Micro-Photoluminescence Study on the Influence of Oxidation on Stacking Faults in 4H-SiC Epilayers
Hikaru Yamagata; Shuhei Yagi; Yasuto Hijikata; Hiroyuki Yaguchi
APPLIED PHYSICS EXPRESS, 巻：5, 号：5, 開始ページ：3, 終了ページ：051302, 2012年05月, ［査読有り］
We have investigated the influence of thermal oxidation on stacking faults (SFs) in 4H-SiC epilayers by performing micro-photoluminescence measurements for 4H-SiC substrates before and after thermal oxidation. We found that SF (emission wavelength: similar to 425.5 nm) thought to be a single Shockley stacking fault was expanded by thermal oxidation. In addition, as a result of comparison between before and after Ar annealing, the SF was not extended after Ar annealing. We also found that only the SFs extended by laser irradiation is eliminated by oxidation. (c) 2012 The Japan Society of Applied Physics
JAPAN SOC APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/APEX.5.051302
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84861398046&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84861398046&origin=inward
DOI ID：10.1143/APEX.5.051302, ISSN：1882-0778, eISSN：1882-0786, ORCID：30384776, SCOPUS ID：84861398046, Web of Science ID：WOS:000303932500005 - TEM Analysis of Structural Phase Transition in MBE Grown Cubic InN on MgO (001) by MBE: Effect of Hexagonal Phase Inclusion in an C-Gan Nucleation Layer
Parinyataramas Jamreonta; Sanorpim Sakuntam; Thanachayanont Chanchana; Yaguchi Hiroyuki; Orihara Misao
Applied Mechanics and Materials, 巻：229-231, 開始ページ：219, 終了ページ：222, 2012年, ［査読有り］
Cubic GaN buffer layer has been used as a nucleation layer to achieve cubic InN layer on MgO (001) substrate grown by molecular beam epitaxy. The highest cubic phase purity of 85% was examined for the cubic InN layer grown on cubic GaN nucleation layer with hexagonal phase inclusion of 4%. It is found that hexagonal phase inclusion in cubic GaN nucleation layer significantly induced structural phase transition in cubic InN layer, which were verified by transmission electron microscopy (TEM). Cross-sectional dark-field TEM images demonstrate parts of stacking faults in cubic GaN nucleation layer, which were observed to generate stacking faults in the cubic InN grown layer. © (2012) Trans Tech Publications, Switzerland.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/AMM.229-231.219
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84871375602&origin=inward
DOI ID：10.4028/www.scientific.net/AMM.229-231.219, ISSN：1660-9336, eISSN：1662-7482, ORCID：30384780, SCOPUS ID：84871375602 - Single Photon Generation from Nitrogen Atomic-Layer Doped Gallium Arsenide
Kengo Takamiya; Yuta Endo; Toshiyuki Fukushima; Shuhei Yagi; Yasuto Hijikata; Toshimitsu Mochizuki; Masahiro Yoshita; Hidefumi Akiyama; Shigeyuki Kuboya; Kentaro Onabe; Ryuji Katayama; Hiroyuki Yaguchi
THERMEC 2011, PTS 1-4, 巻：706-709, 開始ページ：2916, 終了ページ：+, 2012年, ［査読有り］
We have studied the properties of photoluminescence (PL) from individual isoelectronic traps formed by nitrogen-nitrogen (NN) pairs in nitrogen atomic-layer doped (ALD) GaAs. Micro-PL measurements were performed to investigate the properties of single photons generated from individual isoelectronic traps. Twin PL peaks were observed from individual isoelectronic traps in nitrogen ALD GaAs(001). The PL transitions at longer and shorter wavelength sides were linearly polarized in the [110] and [1-10] directions, respectively. The peak splitting and polarization properties can be explained by some in-plane anisotropy most likely due to strain in host crystal. From individual isoelectronic traps in nitrogen ALD GaAs(111), a single PL peak with random polarization was observed, showing that the growth on (111) surface is an effective way to obtain unpolarized single photons. As for nitrogen ALD GaAs(110), different polarization properties were obtained depending on the atomic configuration of NN pairs. in addition, we have used AlGaAs layers to diminish the in-plane anisotropy and could successfully obtained single emission lines with unpolarized character. Introducing AlGaAs layers was also useful for improving the luminescence efficiency.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.706-709.2916
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84856180201&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84856180201&origin=inward
DOI ID：10.4028/www.scientific.net/MSF.706-709.2916, ISSN：0255-5476, ORCID：30384779, SCOPUS ID：84856180201, Web of Science ID：WOS:000308517301220, 共同研究・競争的資金等ID：11611368 - RF-MBE growth of semipolar InN(10-13) and InGaN(10-13) on GaAs(110)
Misao Orihara; Shuhei Yagi; Yasuto Hijikata; Hiroyuki Yaguchi
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 9, NO 3-4, 巻：9, 号：3-4, 開始ページ：658, 終了ページ：661, 2012年, ［査読有り］
We have studied InN and InGaN films grown on GaAs(110) substrates by RF-assisted molecular beam epitaxy. Reflection high-energy diffraction observation and X-ray diffraction (XRD) measurements revealed that the InN films were epitaxially grown with InN(10-13)//GaAs(110). From XRD pole figure measurements, only one InN(0002) peak was found at an angle of 31.8 degrees from the pole, indicating that the semipolar InN films were free from twin crystals. This can be explained by the similarity in the anisotropic structure between InN(10-13) and GaAs(110) surfaces. By using low-temperature InN buffer layers, we could obtain semipolar InN films with a smooth surface. Polarization anisotropy in the photoluminescence peak observed at 0.67 eV from semipolar InN(10-13) was weaker than that from alpha-plane InN, which is reasonable considering the smaller angle between the c-axis and the perpendicular direction to the semipolar InN surface. We have also successfully grown In-rich InGaN(10-13) on GaAs(110) substrates with an InN(10-13) intermediate layer, and observed strong photoluminescence from the semipolar InGaN films. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.201100365
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84858842029&origin=inward
DOI ID：10.1002/pssc.201100365, ISSN：1862-6351, eISSN：1610-1642, ORCID：30384778, SCOPUS ID：84858842029, Web of Science ID：WOS:000306521600059 - Influence of off-cut angle of (0001) 4H-SiC on the crystal quality of InN grown by RF-MBE
Jantawongrit P; Sanorpim S; Yaguchi H; Orihara M; Limsuwan P
Procedia Engineering, 巻：32, 開始ページ：882, 終了ページ：887, 2012年, ［査読有り］
The effect of the off-cut angle of a 4H-SiC (0001) substrate on the growth of InN thick layer by RF-plasma assisted molecular beam epitaxy (RF-MBE) has been investigated. The off-cut angle used in this study was inclined from 0° (just surface) toward the [11-20] direction of 4° and 8°. Crystalline quality and surface morphology were remarkably sensitive to the value of off-angle. Higher off-cut angles result in a reduction of the full-widths at half-maximum of HRXRD (0002) ω-scans, compared to that of the layer on the (0001)-just surface. In addition, the full-widths at halfmaximum of μ-Raman scattering spectra at 490 cm-1, which is attributed to E2 (high) phonon mode, was decreased with increase in off-cut angle. Furthermore, In-droplets, which are commonly observed on the (0001) InN grown surface under In rich-growth condition, were found to be suppressed owing to an improvement of a nucleation on the off-cut angle surface. In our case, the use of 8°-off substrate increased film density and growth rate, while a surface roughness was reduced. These results clearly demonstrate that the larger off-cut angles improve the crystalline quality of InN film with reducing the In-droplets due to a higher step surface density on the off-cut angle surface. © 2010 Published by Elsevier Ltd.
ELSEVIER SCIENCE BV, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1016/j.proeng.2012.02.027
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84892615166&origin=inward
DOI ID：10.1016/j.proeng.2012.02.027, ISSN：1877-7058, ORCID：30384775, SCOPUS ID：84892615166, Web of Science ID：WOS:000393153200127 - Analysis of the Energy Structure of Nitrogen delta-Doped GaAs Superlattices for High Efficiency Intermediate Band Solar Cells
Shunsuke Noguchi; Shuhei Yagi; Yasuto Hijikata; Kentaro Onabe; Shigeyuki Kuboya; Hiroyuki Yaguchi
2012 38TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC), 開始ページ：83, 終了ページ：86, 2012年, ［査読有り］
Nitrogen delta-doped GaAs superlattices were fabricated and their energy structures were investigated. Several transitions related to E+ band of nitrogen delta-doped regions were observed in photoreflectance ( PR) spectra at energies ranging 1.5-1.7 eV for the superlattices at which no transitions were observed for uniformly doped GaAsN. The PR signal intensity of E+ related band transitions is significantly higher than those observed in uniformly doped GaAsN. This enhancement of E+ related band transitions is advantageous as an intermediate band material, and thus, nitrogen delta-doped GaAs superlattice structures are expected to be an excellent alternative for the use of intermediate band solar cells.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/PVSC.2012.6317573
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84869429937&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84869429937&origin=inward
DOI ID：10.1109/PVSC.2012.6317573, ISSN：0160-8371, ORCID：30384773, SCOPUS ID：84869429937, Web of Science ID：WOS:000309917800019 - Quantum well double barrier resonant tunneling structures for selective contacts of hot carrier solar cells
Shuhei Yagi; Yasuto Hijikata; Yoshitaka Okada; Hiroyuki Yaguchi
Conference Record of the IEEE Photovoltaic Specialists Conference, 開始ページ：003309, 終了ページ：003312, 2011年, ［査読有り］
Properties of hot carrier solar cells (HCSC) with several types of selective contacts are analyzed. Quantum dots (QD) based double barrier resonant tunneling structures (DBRTS), quantum well (QW) based DBRTS and single barrier (SB) structures are considered as selective contacts and the possibility of selective contacts consist of simpler structures is studied. The analytical method is based on a detailed balance calculation taking into account the energy distribution of carriers transmitting the selective contacts. Calculated results indicate that the maximum conversion efficiency of HCSC with the absorber band gap of 0.7 eV reaches 64% and 57% for the use of selective contacts consist of a QW-DBRTS and a SB structure, respectively, under full concentrated blackbody radiation at 5760K. Although these values are less than the maximum efficiency of the ideal HCSC (80%) with the same absorber band gap, they are still considerably higher than the efficiency limit of conventional solar cells. Due to its simplicity and maturity of fabrication technique, to use selective contacts consist of simpler structures such as QW-DBRTS and SB structures should be reasonable and attractive alternative for experimental investigation on HCSC. © 2011 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/PVSC.2011.6186646
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84861083769&origin=inward
DOI ID：10.1109/PVSC.2011.6186646, ISSN：0160-8371, ORCID：56291629, SCOPUS ID：84861083769 - Theoretical studies for Si and C emission into SiC layer during oxidation
Yasuto Hijikata; Hiroyuki Yaguchi; Sadafumi Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2010, 巻：679-680, 開始ページ：429, 終了ページ：+, 2011年, ［査読有り］
To understand the structure of SiC-oxide interface more in detail, we propose a profiling theory of Si and C emission into SiC layer during oxidation. Simulations of the depth profiles of Si and C interstitials results in the structures analogous with those observed from a spectroscopic ellipsometry. To determine the diffusivities of Si and C interstitials, we performed capacitance-voltage measurements for examining the re-distribution profiles of nitrogen after oxidation and compared between observed and calculated profile. The calculated nitrogen profiles showed good fits to the observed ones in the case of self-diffusivity of C interstitials magnified by several 10 times for literature value. Finally, we discuss the validity of the proposed theory.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.679-680.429
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=79955121573&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=79955121573&origin=inward
DOI ID：10.4028/www.scientific.net/MSF.679-680.429, ISSN：0255-5476, ORCID：30384784, SCOPUS ID：79955121573, Web of Science ID：WOS:000291673500102 - Single photon emission from nitrogen delta-doped semiconductors
Hiroyuki Yaguchi
QUANTUM SENSING AND NANOPHOTONIC DEVICES VIII, 巻：7945, 開始ページ：79452F, 終了ページ：79452F, 2011年, ［査読有り］
Isolated isolectronic traps in semiconductors are promising candidates for single-photon emitters because sharp emission lines with well-defined wavelengths are readily obtained. In this work, we study the emission from individual isoelectronic traps formed by nitrogen-nitrogen pairs in nitrogen delta (delta)-doped GaAs grown on (001) and (111) A substrates. We have found there is a remarkable difference in the polarization properties of luminescence for between (001) and (111) substrates, and successfully obtained unpolarized single photons by utilizing (111) substrate, which are desirable for the application to quantum cryptography. Unpolarized photons could also be obtained from nitrogen delta-doped GaAs/AlGaAs heterostructures grown on (001) substrates.
SPIE-INT SOC OPTICAL ENGINEERING, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.865770
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=79955781808&origin=inward
DOI ID：10.1117/12.865770, ISSN：0277-786X, ORCID：30384783, SCOPUS ID：79955781808, Web of Science ID：WOS:000293695800066 - High Cubic-Phase Purity InN on MgO (001) Using Cubic-Phase GaN as a Buffer Layer
Sanorpim S; Kuntharin S; Parinyataramas J; Yaguchi H; Iwahashi Y; Orihara M; Hijikata Y; Yoshida S
PHYSICS OF SEMICONDUCTORS: 30th International Conference on the Physics of Semiconductors. AIP Conference Proceedings, 巻：1399, 開始ページ：131, 終了ページ：132, 2011年, ［査読有り］
High cubic-phase purity InN films were grown on MgO (001) substrates by molecular beam epitaxy with a cubic-phase GaN buffer layer. The cubic phase purity of the InN grown layers has been analyzed by high resolution X-ray diffraction, μ-Raman scattering and transmission electron microscopy. It is evidenced that the hexagonal-phase content in the InN overlayer much depends on hexagonal-phase content in the cubic-phase GaN buffer layer and increases with increasing the hexagonal-phase GaN content. From Raman scattering measurements, in addition, the InN layer with lowest hexagonal component (6%), only Raman characteristics of cubic TO InN and LO InN modes were observed, indicating a formation of a small amount of stacking faults, which does not affect on vibrational property. © 2011 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1063/1.3666291
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84855479154&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84855479154&origin=inward
DOI ID：10.1063/1.3666291, ISSN：0094-243X, eISSN：1551-7616, ORCID：30384782, SCOPUS ID：84855479154, Web of Science ID：WOS:000301053000053 - Photoluminescence from single isoelectronic traps in nitrogen delta-doped GaAs grown on GaAs(1 1 1)A
Fukushima T; Hijikata Y; Yaguchi H; Yoshida S; Okano M; Yoshita M; Akiyama H; Kuboya S; Katayama R; Onabe K
Physica E-Low-Dimensional Systems & Nanostructures, 巻：42, 号：10, 開始ページ：2529, 終了ページ：2531, 2010年09月, ［査読有り］
We have studied photoluminescence (PL) observed from single isoelectronic traps formed by nitrogen pairs in nitrogen δ-doped GaAs layers grown on GaAs(1 1 1)A substrates. The PL was composed of a single peak with a narrow linewidth of ∼80 μeV. Polarized PL measurements confirmed that the emission from single isoelectronic traps in nitrogen δ-doped GaAs(1 1 1) is unpolarized irrespective of nitrogen pair arrangements. These results can be explained by in-plane isotropy of the samples, which is consistent with the symmetrical property of GaAs(1 1 1), and demonstrate that utilizing (1 1 1) substrate is an effective means for obtaining unpolarized single photons, which are desirable for the application to quantum cryptography. © 2009 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1016/j.physe.2009.12.011
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=77958003985&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=77958003985&origin=inward
DOI ID：10.1016/j.physe.2009.12.011, ISSN：1386-9477, eISSN：1873-1759, ORCID：30384787, SCOPUS ID：77958003985, Web of Science ID：WOS:000284723200013 - RF-MBE growth of InN on 4H-SiC (0001) with off-angles
Misao Orihara; Shin Takizawa; Takanori Sato; Yuuki Ishida; Sadafumi Yoshida; Yasuto Hijikata; Hiroyuki Yaguchi
PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 7, NO 7-8, 巻：7, 号：7-8, 開始ページ：2016, 終了ページ：2018, 2010年, ［査読有り］
We have grown InN on 4H-SiC (0001) substrates with various off-angles by RF-N-2 plasma molecular beam epitaxy (RF-MBE). Scanning electron microscope observation revealed that InN films grown on 4H-SiC (0001) substrates with off-angles of 4 degrees and 8 degrees are very smooth and that there are no voids which have often observed for InN epitaxial layers. X-ray diffraction reciprocal space maps for InN grown on 4H-SiC (0001) showed that the c-axes of InN grown on 4H-SiC 4 degrees and 8 degrees off substrates are inclined by 0.35 degrees and 0.8 degrees, respectively, toward the misorientation of the substrate while the c-axis of InN is parallel to that of 4H-SiC for the on-axis substrate. Strong PL peak was observed from InN grown on 4 degrees off substrate at 0.68 eV at 15 K. The PL peak was clearly observed even at room temperature and simply shifted to lower energies with increasing temperature. The difference in the PL peak energy between at 15 K and 300 K was 20 meV, which is reasonable taking into account the difference in the thermal coefficients of InN and SiC. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200983441
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=77955823769&origin=inward
DOI ID：10.1002/pssc.200983441, ISSN：1862-6351, eISSN：1610-1642, ORCID：30384788, SCOPUS ID：77955823769, Web of Science ID：WOS:000301587600083 - Model calculations of SiC oxide growth rate at various oxidation temperatures based on the silicon and carbon emission model
Hijikata Yasuto; Yaguchi Hiroyuki; Yoshida Sadafumi
Materials Science Forum, 巻：645-648, 開始ページ：809, 終了ページ：812, 2010年, ［査読有り］
Trans Tech Publications, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.645-648.809
DOI ID：10.4028/www.scientific.net/MSF.645-648.809, ISSN：0255-5476, ORCID：30384786, Web of Science ID：WOS:000279657600192 - In-situ Spectroscopic Ellipsometry Study of SiC Oxidation at Low Oxygen-Partial-Pressures
K. Kouda; Y. Hijikata; H. Yaguchi; S. Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2009, PTS 1 AND 2, 巻：645-648, 開始ページ：813, 終了ページ：+, 2010年, ［査読有り］
We have investigated the oxidation process of SiC (000-1) C-face at low oxygen partial pressures using an in-situ spectroscopic ellipsometry. The oxide growth rate decreased steeply at the early stage of oxidation and then slowly decreased with increasing oxide thickness. The initial oxide growth rate was almost proportional to the oxygen partial pressure for both the polar directions. This result suggests that the initial interfacial reaction rate is constant regardless of the concentration of oxidants reaching the interface.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.645-648.813
DOI ID：10.4028/www.scientific.net/MSF.645-648.813, ISSN：0255-5476, ORCID：30384785, Web of Science ID：WOS:000279657600193 - Optical and electrical characterizations of 4H-SiC-oxide interfaces by spectroscopic ellipsometry and capacitance-voltage measurements
Hashimoto Hideki; Hijikata Yasuto; Yaguchi Hiroyuki; Yoshida Sadafumi
Applied Surface Science, 巻：255, 号：20, 開始ページ：8648, 終了ページ：8653, 2009年07月, ［査読有り］
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.apsusc.2009.06.058
DOI ID：10.1016/j.apsusc.2009.06.058, ISSN：0169-4332, ORCID：30384794, Web of Science ID：WOS:000268123800057 - A Kinetic Model of Silicon Carbide Oxidation Based on the Interfacial Silicon and Carbon Emission Phenomenon
Hijikata Yasuto; Yaguchi Hiroyuki; Yoshida Sadafumi
Applied Physics Express, 巻：2, 号：2, 開始ページ：021203, 終了ページ：021203, 2009年02月, ［査読有り］
{IOP} Publishing, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/APEX.2.021203
DOI ID：10.1143/APEX.2.021203, ISSN：1882-0778, ORCID：30384789, Web of Science ID：WOS:000264942800007 - Model Calculation of SiC Oxidation Rates in the Thin Oxide Regime
Yasuto Hijikata; Takeshi Yamamoto; Hiroyuki Yaguchi; Sadafumi Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2007, PTS 1 AND 2, 巻：600-603, 開始ページ：663, 終了ページ：666, 2009年, ［査読有り］
To explain the growth rate enhancement of SiC oxidation in the thin oxide regime, which was recently found from the real time monitoring experiments of the initial oxidation stage of SiC (000-1) C-face using an in-situ spectroscopic ellipsometer, we tried to apply the interfacial Si emission model, which has been originally proposed for Si oxidation, and found that the Si emission model successfully reproduced the SiC oxidation rates at the whole range of oxide thickness and at oxidation temperatures measured. By comparing with the simulations for Si oxidation, we have discussed the oxidation mechanism of SiC.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.600-603.663
DOI ID：10.4028/www.scientific.net/MSF.600-603.663, ISSN：0255-5476, ORCID：48141545, Web of Science ID：WOS:000263555300158 - Oxygen-Partial-Pressure Dependence of SiC Oxidation Rate Studied by In-situ Spectroscopic Ellipsometry
Takeshi Yamamoto; Yasuto Hijikata; Hiroyuki Yaguchi; Sadafumi Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2007, PTS 1 AND 2, 巻：600-603, 開始ページ：667, 終了ページ：670, 2009年, ［査読有り］
Real time observations of SiC (000-1) C-face and (0001) Si-face oxidation were performed using an in-situ ellipsometer over the oxygen-partial-pressure range from 0.1 to 1.0 atm. We analyzed the relations between oxide growth rate and oxide thickness by applying an empirical relation proposed by Massoud et al. We found the occurrence of oxidation enhancement in the thin oxide regime also for Si-face as well as for C-face. We have discussed the oxygen-partial-pressure dependence of the oxidation rate constants between SiC C- and Si face, comparing with that of Si. © (2009) Trans Tech Publications, Switzerland.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.600-603.667
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DOI ID：10.4028/www.scientific.net/MSF.600-603.667, ISSN：0255-5476, ORCID：48141546, SCOPUS ID：60349127717, Web of Science ID：WOS:000263555300159 - Observation of SiC Oxidation in Ultra-thin Oxide Regime by In-situ Spectroscopic Ellipsometry
Toshiyuki Takaku; Yasuto Hijikata; Hiroyuki Yaguchi; Sadafumi Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2008, 巻：615-617, 開始ページ：509, 終了ページ：512, 2009年, ［査読有り］
Thermal oxidation process of silicon carbide in ultra-thin oxide regime has been studied by performing in-situ and real time spectroscopic ellipsometry. We found the thermal oxidation at 700°C forms no or extremely thin interface layers between SiC and oxide layers. In contrast, the oxidation at 850°C forms an interface layer of around 1 nm in thickness, having similar thickness and optical constants of the interface layers formed by the oxidation at higher temperature than 1000°C. To make clear the conditions no interface layer is formed, i.e., whether low temperature growth or thin oxide thickness is crucial, we have performed the oxidation at 850°C in the reduced oxygen pressure. Based on the results of these experiments, we discussed the origin of the formation of interface layers as well as the oxidation mechanism of SiC. © (2009) Trans Tech Publications.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.615-617.509
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=77955444151&origin=inward
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DOI ID：10.4028/www.scientific.net/MSF.615-617.509, ISSN：0255-5476, ORCID：48141803, SCOPUS ID：77955444151, Web of Science ID：WOS:000265961100122 - Characterization of 4H-SiC-SiO2 Interfaces by a Deep Ultraviolet Spectroscopic Ellipsometer
H. Seki; T. Wakabayashi; Y. Hijikata; H. Yaguchi; S. Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2008, 巻：615-617, 開始ページ：505, 終了ページ：508, 2009年, ［査読有り］
We have characterized 4H-SiC-oxide interfaces fabricated by thermal oxidation of SiC using spectroscopic ellipsometry in the wide spectral range from visible to deep UV region. It was found that there exists an interface layer, around 1 nm in thickness, regardless of the oxide thickness from 15 nm to 40 nm. The optical constants of the interface layer have similar spectral dependence to those of SiC, though the absolute value of the refractive indices is 0.5-1 larger than that of SiC. We have discussed the structure of the interface layer based oil the oxidation mechanism of SiC, like the Si-emission model.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.615-617.505
DOI ID：10.4028/www.scientific.net/MSF.615-617.505, ISSN：0255-5476, ORCID：48141548, Web of Science ID：WOS:000265961100121 - Model Calculation of SiC Oxide Growth Rate Based on the Silicon and Carbon Emission Model
Yasuto Hijikata; Hiroyuki Yaguchi; Sadafumi Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2008, 巻：615-617, 開始ページ：489, 終了ページ：492, 2009年, ［査読有り］
We proposed a kinetic model For SiC oxidation, named 'silicon and carbon (Si-C) emission model', taking into account the emission of Si and C atoms from the SiC-oxide interface, which suppresses the oxidation rate at the interface. Based oil the model, we calculated oxide growth rates for SiC (0001) Si- and (000-1) C-face and found that the calculated values exhibit good fits to the measured ones in the entire oxide thickness range for both faces. We also calculated depth profiles of Si and C interstitials and oxidants, and discussed the oxidation mechanism of SiC as well as the difference in the oxidation process of Si-face and C-face.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.615-617.489
DOI ID：10.4028/www.scientific.net/MSF.615-617.489, ISSN：0255-5476, Web of Science ID：WOS:000265961100117 - Oxide Growth Rate Enhancement of Silicon Carbide (0001) Si-Faces in Thin Oxide Regime
Yamamoto Takeshi; Hijikata Yasuto; Yaguchi Hiroyuki; Yoshida Sadafumi
Japanese Journal of Applied Physics, 巻：47, 号：10, 開始ページ：7803, 終了ページ：7806, 2008年10月, ［査読有り］
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.47.7803
DOI ID：10.1143/JJAP.47.7803, ISSN：0021-4922, ORCID：30384797, Web of Science ID：WOS:000260443900009 - Twin photoluminescence peaks from single isoelectronic traps in nitrogen delta-doped GaAs
Y. Endo; Y. Hijikata; H. Yaguchi; S. Yoshida; M. Yoshita; H. Akiyama; F. Nakajima; R. Katayama; K. Onabe
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES, 巻：40, 号：6, 開始ページ：2110, 終了ページ：2112, 2008年04月, ［査読有り］
We report on twin emission peaks observed from single isoelectronic traps formed by nitrogen pairs in nitrogen delta-doped GaAs by high-energy resolution micro-photoluminescence (PL) spectroscopy. The twin PL peaks show almost the same intensity with narrow linewidths of 20-50 mu eV, which are considerably smaller than that ever reported for isoelectronic traps in GaAs:N. The higher and lower energy luminescence transitions were linearly polarized in the [1 (1) over bar 0] and [1 1 0] directions, respectively, indicating that the two exciton states have completely orthogonal relations with each other. The fact that any pair of the twin PL peaks has the same polarization properties suggests that the splitting is due to the anisotropy between [1 (1) over bar 0] and [1 1 0] directions in the host crystal and is possibly explained by the strain anisotropy in the sample. (C) 2007 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.physe.2007.10.047
DOI ID：10.1016/j.physe.2007.10.047, ISSN：1386-9477, ORCID：30384800, Web of Science ID：WOS:000255717400104 - High resolution X- ray diffraction and raman scattering studies of cubic-phase InN films grown by MBE
S. Kuntharin; S. Sanorpim; H. Yaguchi; Y. Iwahashi; M. Orihara; Y. Hijakata; S. Yoshida
Advanced Materials Research, 巻：55-57, 開始ページ：773, 終了ページ：776, 2008年, ［査読有り］
We demonstrate the use of high resolution X-ray diffraction and Raman scattering to assess the generation of hexagonal-phase in the cubic-phase InN (c-InN) films on MgO substrates grown by molecular beam epitaxy with a cubic-phase GaN buffer layer. The X-ray reciprocal-lattice space mapping was used to examine the hexagonal-phase generated on the cubic (111) planes in the c-InN films. Ratio of hexagonal to cubic components in the c-InN grown layers was estimated from the ratio of the integrated X-ray diffraction intensities of cubic (002) and hexagonal (10-11) reflections measured by co-scans. Amount of hexagonal-phase presented in the c-InN films was determined in the range of 6 to 24%. It was found that the Raman characteristics are also sensitive to hexagonal-phase presented in the c-InN films. For the lowest amount of hexagonal-phase (6%), only Raman scattering characteristics of c-InN was observed, indicating formation of a small amount of stacking faults, which not affected on the vibrational property. Based on our results, relatively easy access to the generation of hexagonal-phase suggests that it may be very useful for HRXRD and Raman scattering measurements of c-InN. © 2008 Trans Tech Publications, Switzerland.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/amr.55-57.773
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DOI ID：10.4028/www.scientific.net/amr.55-57.773, ISSN：1022-6680, SCOPUS ID：63049097802 - Photoluminescence study of hexagonal InN/InGaN quantum well structures grown on 3C-SiC (001) substrates by molecular beam epitaxy
S. Hirano; T. Inoue; G. Shikata; M. Orihara; Y. Hijikata; H. Yaguchi; S. Yoshida; Y. Hirabayashi
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 5, NO 6, 巻：5, 号：6, 開始ページ：1730, 終了ページ：+, 2008年, ［査読有り］
We have studied photoluminescence from hexagonal InN/InGaN multiple quantum well structures grown on 3C-SiC (001) substrates with an InGaN underlayer by plasma assisted-molecular beam epitaxy. We have observed photoluminescence spectra of InN/InGaN MQWs with various well widths. The photoluminescence peak related to quantum wells was clearly observed even at room temperature and found to shift to higher energies with decreasing well width due to the quantum confinement effect. We also discuss the effect of the built-in electric fields on the PL peak energy. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200778606
DOI ID：10.1002/pssc.200778606, ISSN：1862-6351, ORCID：30384799, Web of Science ID：WOS:000256695700075 - Photoluminescence of cubic InN films on MgO (001) substrates
T. Inoue; Y. Iwahashi; S. Oishi; M. Orihara; Y. Hijikata; H. Yaguchi; S. Yoshida
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 5, NO 6, 巻：5, 号：6, 開始ページ：1579, 終了ページ：1581, 2008年, ［査読有り］
We have studied photoluminescence from cubic InN films grown on MgO substrates with a cubic GaN underlayer by RF N(2) plasma molecular beam epitaxy. A single PL peak was observed at 0.47 eV. By analyzing the reflectance spectra of cubic InN films, we could derive the refractive index and extinction coefficient, and found the band gap energy of cubic InN is 0.48 eV, indicating that the PL peak observed at 0.47 eV is due to the interband transition of cubic InN. The difference in the PL peak energy between hexagonal and cubic InN is in good agreement with that predicted by ab-initio calculations.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200778505
DOI ID：10.1002/pssc.200778505, ISSN：1862-6351, ORCID：30384798, Web of Science ID：WOS:000256695700031 - Improvement of the surface morphology of a-plane InN using low-temperature InN buffer layers
G. Shikata; S. Hirano; T. Inoue; M. Orihara; Y. Hijikata; H. Yaguchi; S. Yoshida
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 5, NO 6, 巻：5, 号：6, 開始ページ：1808, 終了ページ：1810, 2008年, ［査読有り］
We report on the improvement of the surface morphology of a-plane InN films grown by RF molecular beam epitaxy. By using low-temperature (LT) InN buffer layers, we could successfully obtain InN films with a smooth surface, The full width at half maximum values of the x-ray diffraction (11-20) rocking curve along the [0001] InN direction were 2870 arcsec and 3410 arcsec for a-plane InN samples grown at 500 degrees C with and without LT-InN buffer layers, respectively. Thus, we-could improve also the crystalline quality of a-plane InN films by using LT-InN buffer layers. We observed strong polarization anisotropy in the photoluminescence spectra of a-plane InN, which is typical of nonpolar wurtzite III-nitride films.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200778662
DOI ID：10.1002/pssc.200778662, ISSN：1862-6351, ORCID：30384796, Web of Science ID：WOS:000256695700100 - Growth rate enhancement of (0001)-face silicon-carbide oxidation in thin oxide regime
Yamamoto Takeshi; Hijikata Yasuto; Yaguchi Hiroyuki; Yoshida Sadafumi
Japanese Journal of Applied Physics Part 2-Letters & Express Letters, 巻：46, 号：29-32, 開始ページ：L770, 終了ページ：L772, 2007年08月, ［査読有り］
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.46.L770
DOI ID：10.1143/JJAP.46.L770, ISSN：0021-4922, ORCID：30384801, Web of Science ID：WOS:000249166000018 - RF-MBE growth of a-plane InN on r-plane sapphire with a GaN underlayer
G. Shikata; S. Hirano; T. Inoue; M. Orihara; Y. Hijikata; H. Yaguchi; S. Yoshida
JOURNAL OF CRYSTAL GROWTH, 巻：301, 開始ページ：517, 終了ページ：520, 2007年04月, ［査読有り］
a-Plane InN films were grown on r-plane sapphire substrates with GaN underlayers by RF-N-2 plasma molecular beam epitaxy (MBE). X-ray diffraction (XRD) measurements and reflection high-energy electron diffraction (RHEED) observation revealed that the InN films were grown with InN (1 1 (2) over bar 0)parallel to GaN (1 1 (2) over bar 0)parallel to sapphire (2 (2) over bar 0 4). We have carried out micro-Raman scattering measurements for a-plane InN film. Raman peaks were observed at 448, 490 and 598 cm(-1), which can be identified as the A(1) transversal optical (TO), E-2 (high) and E-1 longitudinal optical (LO) mode phonon, respectively. We also carried out photoluminescence (PL) measurements for a-plane InN film. Strong PL was observed between 0.62 and 0.65 eV, which is the lowest ever reported for InN. It is suggested from the excitation intensity and temperature dependence of the PL spectra that the red shift of the PL peak is due to the Franz-Keldysh effect. (c) 2006 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.jcrysgro.2006.11.072
DOI ID：10.1016/j.jcrysgro.2006.11.072, ISSN：0022-0248, eISSN：1873-5002, ORCID：30384808, Web of Science ID：WOS:000246015800119 - RF-MBE growth of InN/InGaN quantum well structures on 3C-SiC substrates
S. Hirano; T. Inoue; G. Shikata; M. Orihara; Y. Hijikata; H. Yaguchi; S. Yoshida
JOURNAL OF CRYSTAL GROWTH, 巻：301, 開始ページ：513, 終了ページ：516, 2007年04月, ［査読有り］
InN/In0.83Ga0.17N multiple quantum well (MQW) structures have been fabricated on 3C-SiC (0 0 1) substrates by radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE). The surface morphology, structural properties, and optical properties of the samples were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL), respectively. XRD satellite peaks due to the periodic structure were clearly observed in the MQW structures grown at temperatures lower than 530 degrees C. PL emissions from the MQW were observed around 0.85 eV. (c) 2006 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.jcrysgro.2006.11.117
DOI ID：10.1016/j.jcrysgro.2006.11.117, ISSN：0022-0248, ORCID：30384809, Web of Science ID：WOS:000246015800118 - Simultaneous determination of the carrier concentration, mobility and thickness of SiC homo-epilayers using terahertz reflectance spectroscopy
Shingo Oishi; Yasuto Hijikata; Hiroyuki Yaguchi; Sadafumi Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2006, 巻：556-557, 開始ページ：423, 終了ページ：+, 2007年, ［査読有り］
We have simultaneously determined the carrier concentration, mobility, and thickness of 414-SiC homo-epilayers with carrier concentration of 10(16)-10(18) cm(-3) from reflectance spectroscopy in the wavenumber range of 20-2000 cm(-1). The spectra at 20-100 cm(-1) and at 80-2000 cm(-1) were measured by using the terahertz time domain spectrometer (THz-TDS) and the Fourier-transform infrared (FTIR) spectrometer, respectively. A modified classical dielectric function (MDF) model was employed for the curve fitting. We have compared the values of free carrier concentrations estimated from the reflectance spectroscopy with the net doping concentrations obtained from C-V measurements, and have discussed the validity of the electrical properties estimated from the reflectance spectroscopy.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.556-557.423
DOI ID：10.4028/www.scientific.net/MSF.556-557.423, ISSN：0255-5476, ORCID：48141549, Web of Science ID：WOS:000249653900101 - Structural and optical characterization of high In content cubic InGaN on GaAs(001) substrates by RF-MBE
Nakamura Teruyuki; Endo Yuta; Katayama Ryuji; Yaguchi Hiroyuki; Onabe Kentaro
physica status solidi (c), 巻：4, 号：7, 開始ページ：2437, 終了ページ：2440, 2007年, ［査読有り］
Wiley, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/pssc.200674803
DOI ID：10.1002/pssc.200674803, ISSN：1862-6351, eISSN：1610-1642, ORCID：30384811, Web of Science ID：WOS:000248047600056 - Photoluminescence study of isoelectronic traps in dilute GaAsN alloys
Yaguchi H; Aoki T; Morioke T; Hijikata Y; Yoshida S; Yoshita M; Akiyama H; Aoki D; Onabe K
physica status solidi (c), 巻：4, 号：7, 開始ページ：2760, 終了ページ：2763, 2007年, ［査読有り］
We have studied photoluminescence spectra in detail to clarify the character of the isoelectronic traps in dilute GaAsN alloys. Several sharp lines have been observed at the lower energy side of the GaAs bandgap and are in good agreement with the nitrogen pair-related emission lines previously reported. In addition to the nitrogen pair-related lines, some other emission lines have been also observed. Compared with the energies of these emission lines and the nitrogen pair-related emission lines, it was found that the energy differences agree with the longitudinal optical phonon energy at the Γ point of GaAs, showing that the character of isoelectronic traps due to nitrogen pairs in dilute GaAsN alloys is significantly contributed from the conduction band state at the Γ point. The temperature dependence of the peak energy of luminescence due to nitrogen pairs also indicates that the character of isoelectronic traps in dilute GaAsN alloys is due to the conduction band edge state at the Γ point of GaAs. For a dilute GaAsN alloy with lower nitrogen concentration, we have observed that the intensity of an emission line increased superlinearly with excitation power. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200674721
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=49749134309&origin=inward
DOI ID：10.1002/pssc.200674721, ISSN：1862-6351, ORCID：30384807, SCOPUS ID：49749134309, Web of Science ID：WOS:000248047600135 - Modulation spectroscopic investigation on lattice polarity of gallium nitride
Katayama Ryuji; Onabe Kentaro; Yaguchi Hiroyuki; Matsushita Tomonori; Kondo Takashi
Applied Physics Letters, 巻：91, 号：6, 2007年, ［査読有り］
A lattice polarity determination method for GaN is demonstrated, which is based on a capability of modulation spectroscopy for the assignment of electric-field directions performed nondestructively using simple optical setups. A strong spontaneous polarization induces an upward band bending toward +c surfaces and a downward but weaker bending toward -c surfaces for typical films with small residual strains and electron densities. This difference is distinguishable in terms of the spectral-phase flip, utilizing photoreflectance, and electroreflectance. Quantitative analysis revealed the exciton dissociation at a high-field region of +c surfaces consistent with the band profile derived as a solution of Poisson equation. © 2007 American Institute of Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.2764115
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=34547842633&origin=inward
DOI ID：10.1063/1.2764115, ISSN：0003-6951, ORCID：30384806, SCOPUS ID：34547842633, Web of Science ID：WOS:000248661400044 - Micro-photoluminescence study of nitrogen delta-doped GaAs grown by metalorganic vapor phase epitaxy
Y. Endo; K. Tanioka; Y. Hijikata; H. Yaguchi; S. Yoshida; M. Yoshita; H. Akiyama; W. Ono; F. Nakajima; R. Katayama; K. Onabe
JOURNAL OF CRYSTAL GROWTH, 巻：298, 開始ページ：73, 終了ページ：75, 2007年01月, ［査読有り］
We have measured micro-photoluminescence (PL) spectra of nitrogen delta (delta)-doped GaAs with various concentrations. In nitrogen delta-doped GaAs with low concentrations, the micro-PL spectra measured at different positions were individually different. In contrast, almost the same spectra were obtained for nitrogen delta-doped GaAs with higher concentrations and uniformly nitrogen-doped GaAs. The micro-PL study shows that there are no more than a few isoelectronic traps within a diameter of similar to 1 mu m. This indicates a good prospect for applications of isoelectronic traps to single photon emitting devices. (c) 2006 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.jcrysgro.2006.10.019
DOI ID：10.1016/j.jcrysgro.2006.10.019, ISSN：0022-0248, ORCID：30384804, Web of Science ID：WOS:000244622600017 - Micro-Raman study on the improvement of luminescence efficiency of GaAsN alloys
K. Tanioka; Y. Endo; Y. Hijikata; H. Yaguchi; S. Yoshida; M. Yoshita; H. Akiyama; K. Onabe
JOURNAL OF CRYSTAL GROWTH, 巻：298, 開始ページ：131, 終了ページ：134, 2007年01月, ［査読有り］
We have used in situ micro-Raman spectroscopy to clarify the mechanism of the luminescence efficiency improvement of GaAsN alloys by laser irradiation. Raman peak intensity of GaAs-like longitudinal optical (LO) mode phonon was observed to increase with the laser irradiation time. With increasing laser power density, the Raman intensity of GaAs-like LO mode phonon was found to increase more rapidly and to be saturated in a shorter time. Changes in the Raman intensity can be expressed by the same equation used for the luminescence efficiency improvement. Time constants of changes in the Raman intensity were almost in agreement with those of the luminescence efficiency improvement. This indicates that the increase in Raman intensity of GaAs-like LO phonon is closely related to the luminescence efficiency improvement. (c) 2006 Published by Elsevier B.V.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.jcrysgro.2006.10.006
DOI ID：10.1016/j.jcrysgro.2006.10.006, ISSN：0022-0248, eISSN：1873-5002, ORCID：30384805, Web of Science ID：WOS:000244622600030 - Simultaneous determination of carrier concentration, mobility, and thickness of SiC homoepilayers by infrared reflectance spectroscopy
Oishi Shingo; Hijikata Yasuto; Yaguchi Hiroyuki; Yoshida Sadafumi
Japanese Journal of Applied Physics Part 2-Letters & Express Letters, 巻：45, 号：46-50, 開始ページ：L1226, 終了ページ：L1229, 2006年12月, ［査読有り］
We have simultaneously determined the carrier concentration, mobility, and thickness of 4H-SiC homoepilayers with carrier concentrations of 10 17-1018 cm-3 from infrared reflectance measurements with the wave number range of 80-2000 cm-1. A modified classical dielectric function model was employed for the fitting analyses. We have prepared n-type epilayers on p-type and n-type substrates for comparison with the values of the carrier concentration and mobility estimated from infrared reflectance measurements with those obtained from Hall-effect measurements and C-V measurements. Through these comparisons, we have confirmed the validity of the values estimated from infrared reflectance measurements. © 2006 The Japan Society of Applied Physics.
INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.45.L1226
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=34547874643&origin=inward
DOI ID：10.1143/JJAP.45.L1226, ISSN：0021-4922, eISSN：1347-4065, ORCID：30384817, SCOPUS ID：34547874643, Web of Science ID：WOS:000243208300002 - Characterization of oxide films on 4H-SiC epitaxial (000(1)over-bar) faces by high-energy-resolution photoemission spectroscopy: Comparison between wet and dry oxidation
Hijikata Yasuto; Yaguchi Hiroyuki; Yoshida Sadafumi; Takata Yasutaka; Kobayashi Keisuke; Nohira Hiroshi; Hattori Takeo
Journal of Applied Physics, 巻：100, 号：5, 2006年09月, ［査読有り］
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.2345471
DOI ID：10.1063/1.2345471, ISSN：0021-8979, ORCID：30384812, Web of Science ID：WOS:000240602500065 - Off-angle dependence of characteristics of 4H-SiC-oxide interfaces
Y. Hijikata; H. Yaguchi; S. Yoshida; Y. Takata; K. Kobayashi; H. Nohira; T. Hattori
Silicon Carbide and Related Materials 2005, Pts 1 and 2, 巻：527-529, 開始ページ：1003, 終了ページ：1006, 2006年, ［査読有り］
SiC-Oxide interfaces on 4H-SiC epitaxial substrates of various off-angles have been characterized by C-V measurements, synchrotron radiation excited photoemission spectroscopy and atomic force microscopy. We found that the interface state density (N-it) and the amount of sub-oxides (S-i) for small off-angle substrates were smaller than those for large off-angle ones. It was also found that there is a good correlation between the amount of the interface states and that of sub-oxides. Step-terrace structures were clearly observed in the surface morphology after the removal of oxide layers for small off-angle substrates, which shows that the interfaces were atomically smooth. These results suggest that the small N-it and S-i values for small off-angle substrates relate to the smoothness of the interface and that high performance SiC MOS devices are expected by using small off-angle substrates.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.527-529.1003
DOI ID：10.4028/www.scientific.net/MSF.527-529.1003, ISSN：0255-5476, ORCID：48141550, Web of Science ID：WOS:000244227200235 - Real time observation of SiC oxidation using an in-situ ellipsometer
Kakubari K; Kuboki R; Hijikata Y; Yaguchi H; Yoshida S; Devaty RP
Materials Science Forum, 巻：527-529, 開始ページ：1031, 終了ページ：1034, 2006年, ［査読有り］
研究論文（学術雑誌）
DOI：https://doi.org/10.4028/WWW.SCIENTIFIC.NET/MSF.527-529.1031
DOI ID：10.4028/WWW.SCIENTIFIC.NET/MSF.527-529.1031, ORCID：30384815, Web of Science ID：WOS:000244227200242 - RF-MBE growth of cubic InN films on MgO (001) substrates
Y. Iwahashi; H. Yaguchi; A. Nishimoto; M. Orihara; Y. Hijikata; S. Yoshida
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 3, NO 6, 巻：3, 号：6, 開始ページ：1515, 終了ページ：1518, 2006年, ［査読有り］
Cubic InN films have been grown on MgO substrates with cubic GaN underlayers by RF-N-2 plasma MBE. By changing the growth conditions, we clarified the growth temperature and In flux dependence of the quality of cubic InN films. It was found the surface of cubic InN films grown at relatively higher temperatures was smooth and that the hexagonal phase content in the InN films decreased with increasing In flux. Based on the findings, we have successfully obtained a c-InN film with high phase-purity and a smooth surface. We have carried out micro Raman scattering measurements for the high-quality cubic InN film. Raman peaks were clearly observed at 596 cm(-1) and 467 cm(-1), which are attributed to longitudinal optical and transverse optical phonon modes of cubic InN, respectively. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
WILEY-VCH, INC, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200565312
DOI ID：10.1002/pssc.200565312, ISSN：1862-6351, ORCID：30384816, Web of Science ID：WOS:000239543600033 - Photo-induced improvement of radiative efficiency and structural changes in GaAsN alloys
H. Yaguchi; T. Morioke; T. Aoki; H. Shimizu; Y. Hijikata; S. Yoshida; M. Yoshita; H. Akiyama; N. Usami; D. Aoki; K. Onabe
PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 3, NO 6, 巻：3, 号：6, 開始ページ：1907, 終了ページ：1910, 2006年, ［査読有り］
We have investigated the excitation power density and nitrogen concentration dependence of the changes in the radiative efficiency of GaAsN alloys to examine the mechanism of the photo-induced improvement of radiative efficiency. With increasing excitation power density, the radiative efficiency increased more rapidly. The measure of the improvement I-after/I-before superlinearly increased with increasing nitrogen concentration x up to similar to 1%. This suggests that the nonradiative recombination centers eliminated by photoexcitation are not defects formed by a single nitrogen atom but complexes formed by gathering of several nitrogen atoms. Micro Raman study revealed that the GaAs-like LO mode phonon peak intensity increased with photoexcitation time in a similar way to the increase in the radiative efficiency. Considering that this phenomenon is in a time scale of several seconds, the photo-induced structural changes correspond not to long range inter-diffusion but to local changes in atomic configuration which lead to the decrease in the density of nonradiative recombination centers. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
WILEY-VCH, INC, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200565372
DOI ID：10.1002/pssc.200565372, ISSN：1862-6351, ORCID：30384814, Web of Science ID：WOS:000239543600124 - Effect of Ar post-oxidation annealing on oxide-4H-SiC interfaces studied by capacitance to voltage measurements and photoemission spectroscopy
Y Hijikata; H Yaguchi; S Yoshida; Y Ishida; M Yoshikawa
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 巻：23, 号：2, 開始ページ：298, 終了ページ：303, 2005年03月, ［査読有り］
The effect of post-oxidation annealing in Ar atmosphere (Ar POA) on 4H-SiC-oxide interfaces. has been studied by capacitance to gate-bias voltage (C-V) measurements and photoemission spectroscopy (PES). It was found from the C-V measurements that the shift of the C-V curve disappears when the Ar POA temperature is higher than 600&DEG; C. On the other hand, angle-resolved x-ray photoelectron spectroscopy measurements revealed that the thickness of the intermediate layers containing Si1+ oxidation states observed at the interfaces decreases abruptly when the Ar POA temperature exceeds 500&DEG; C. In ultraviolet photoelectron spectra, O2p, peaks were changed by Ar POA at temperatures higher than 600&DEG; C, which is the temperature where the shift of the C-V curve disappears in C-V measurements. This shows that the change in O2p bonding by Ar POA is the origin of the shift observed in C-V characteristics. A model of structural changes in the interfaces by Ar POA has been proposed based on the results of PES measurements and those of C-V measurements. © 2005 American Vacuum Society.
A V S AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1116/1.1865153
DOI ID：10.1116/1.1865153, ISSN：0734-2101, eISSN：1520-8559, ORCID：30384819, Web of Science ID：WOS:000227739200013 - Characterization of oxide films on SIC epitaxial (000-1) faces by angle-resolved photoemission spectroscopy measurements using synchrotron radiation
A Hijikata; H Yaguchi; S Yoshida; Y Takata; K Kobayashi; S Shin; H Nohira; T Hattori
SILICON CARBIDE AND RELATED MATERIALS 2004, 巻：483, 開始ページ：585, 終了ページ：588, 2005年
Thermal oxide films on SiC epitaxial (000-1) C-faces have been characterized by angle-resolved photoemission spectroscopy (AR-PES). The structure of wet oxide/SiC C-face interface was compared with that of dry oxide/SiC C-face, as well as that of dry oxide/SiC Si-face, in order to clarify why a MOS device of SiC C-face achieved good electrical properties. The improvement in electrical properties was confirmed by AR-PES measurements, evidencing differences in binding energy between SiC and the Si4+ components in Si2p and valence band region, and in binding energy between SiC and the CH, components in C1s. The reason for the improvement in electrical property of MOS devices by use of SiC C-face are discussed in terms of depth profiles of oxide films calculated from the AR-PES results.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.483-485.585
DOI ID：10.4028/www.scientific.net/MSF.483-485.585, ISSN：0255-5476, ORCID：56291594, Web of Science ID：WOS:000228549600137 - Growth of high-quality hexagonal InN on 3C-SiC (001) by molecular beam epitaxy
H Yaguchi; Y Kitamura; K Nishida; Y Iwahashi; Y Hijikata; S Yoshida
PHYSICA STATUS SOLIDI C - CONFERENCES AND CRITICAL REVIEWS, VOL 2, NO 7, 巻：2, 号：7, 開始ページ：2267, 終了ページ：2270, 2005年, ［査読有り］
We have grown hexagonal InN (h-InN) films on 3C-SiC (001) substrates by RF-N-2 plasma molecular beam epitaxy taking account of small lattice mismatch between h-InN (10-10) and 3C-SiC (110). It was found from X-ray diffraction (XRD) measurements that h-InN grows with h-InN (0001) 11 3C-SiC (001) and h-InN (1-100) vertical bar vertical bar 3C-SiC (110). XRD measurements also revealed that the h-InN epitaxial layers grown on 3C-SiC (001) are composed of single domain. Strong and sharp photoluminescence from the h-InN was clearly observed at around 0.69 eV. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200461386
DOI ID：10.1002/pssc.200461386, ISSN：1862-6351, ORCID：30384820, Web of Science ID：WOS:000230421400058 - Epitaxial growth of hexagonal and cubic InN films
Nishida K; Kitamura Y; Hijikata Y; Yaguchi H; Yoshida S
Physica Status Solidi B-Basic Research, 巻：241, 号：12, 開始ページ：2839, 終了ページ：2842, 2004年10月, ［査読有り］
We have grown InN films on 3C-SiC (001) substrates with and without cubic GaN underlayers by RF-N2 plasma MBE. It was found that, in the case of direct growth on 3C-SiC (001), hexagonal InN grows with the crystal orientation as hexagonal InN (1100)//3C-SiC (110), while, in the case of the growth on cubic GaN underlayers, cubic InN grows with the crystal orientation as cubic InN (110)//cubic GaN (110). Photoluminescence emissions from the cubic and hexagonal InN films were clearly observed at around 0.7 eV. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssb.200405049
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=7444245442&origin=inward
DOI ID：10.1002/pssb.200405049, ISSN：0370-1972, ORCID：30384823, SCOPUS ID：7444245442 - Characterization of carrier concentration and mobility in n-type SiC wafers using infrared reflectance spectroscopy
Narita K; Huikata Y; Yaguchi H; Yoshida S; Nakashima S
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：43, 号：8 A, 開始ページ：5151, 終了ページ：5156, 2004年08月, ［査読有り］
We have estimated the free-carrier concentration and drift mobility in n-type 6H-SiC wafers in the carrier concentration range of 10 17-1019 cm3 from far- and mid-infrared (30-2000 cm -1) reflectance spectra obtained at room temperature. A modified classical dielectric function model was employed for the analysis. We found good agreement between the electrical properties derived from infrared reflectance spectroscopy and those derived from Hall effect measurements. We have demonstrated the spatial mapping of carrier concentration and mobility for commercially produced 2 inch SiC wafers.
INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.43.5151
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=6444243848&origin=inward
DOI ID：10.1143/JJAP.43.5151, ISSN：0021-4922, ORCID：30384821, SCOPUS ID：6444243848, Web of Science ID：WOS:000224841400013 - Characterization of electrical properties in high-dose implanted and post-implantation-annealed 4H-SiC wafers using infrared reflectance spectroscopy
K Narita; Y Hijikata; H Yaguchi; S Yoshida; J Senzaki; S Nakashima
SILICON CARBIDE AND RELATED MATERIALS 2003, PRTS 1 AND 2, 巻：457-460, 開始ページ：905, 終了ページ：908, 2004年, ［査読有り］
Infrared reflectance spectroscopy has been used to characterize the electrical properties and crystalline damage of high-dose implanted and post-implantation-annealed 4H-SiC. The carrier concentration, mobility and crystalline damage were independently derived from the analysis of the infrared reflectance spectra using the effective medium approximation and the modified dielectric function taking into account the TO and LO phonon damping factors independently. The carrier concentration and mobility in the recrystallized SiC derived from infrared reflectance spectra are in good agreement with those obtained from Hall effect measurements. The annealing temperature dependence of crystalline damage suggests that the impurities are almost activated by the annealing at a temperature as low as 1200degreesC for 30 min, though the crystallinity of the implanted layer is improved with increasing annealing temperature. In addition, it is revealed that the annealing at a temperature as high as 1700degreesC recovers the crystallinity of the implanted layer within I min. These results demonstrate that the infrared reflectance spectroscopy is a useful technique to characterize both the electrical properties and crystalline damage of implanted and post-implantation-annealed layers in SiC wafers simultaneously.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.457-460.905
DOI ID：10.4028/www.scientific.net/MSF.457-460.905, ISSN：0255-5476, ORCID：56291630, Web of Science ID：WOS:000222802200215 - Photoemission spectroscopic studies on oxide/SiC interfaces formed by dry and pyrogenic oxidation
Y Hijikata; H Yaguchi; Y Ishida; M Yoshikawa; T Kamiya; S Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2003, PRTS 1 AND 2, 巻：457-460, 開始ページ：1341, 終了ページ：1344, 2004年, ［査読有り］
The difference in the structure of oxide/SiC interface between dry and pyrogenic oxidation and the effect of post-oxidation annealing in Ar atmosphere on the interfaces have been studied by X-ray and ultraviolet photoelectron spectroscopy to make clear the interface structures which spoil the electrical properties. It is found that intermediate layers containing Si1+ oxidation states exist in both cases of oxidation method and the thickness of the layer changes by Ar annealing. It is also found that the oxide/SiC band offsets and the structures of O2p peak, observed in valence band spectra, change remarkably by Ar POA in both cases of oxidation method. The bond states at SiC/oxide interfaces have been discussed by considering these results together with the results from C-V measurements.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.457-460.1341
DOI ID：10.4028/www.scientific.net/MSF.457-460.1341, ISSN：0255-5476, ORCID：48141565, Web of Science ID：WOS:000222802200319 - Spectroscopic ellipsometry study on the dielectric functions of GaPN alloys
Kanaya H; Yaguchi H; Hijikata Y; Yoshida S; Miyoshi S; Onabe K; Stutzmann M
Physica Status Solidi C: Conferences, 巻：0, 号：7, 開始ページ：2753, 終了ページ：2756, 2003年, ［査読有り］
We have determined the complex dielectric functions of GaP 1-xNx alloys using spectroscopic ellipsometry to clarify the electronic structure. With increasing N concentration, the E1-gap peak height for both ε1 and ε2 decreases and the E1-gap energy shifts to higher energies, showing that the electronic state at the L point is considerably changed due to the N incorporation. In the lower energy range, a broad peak appears near the fundamental band gap energy of GaP. With increasing N concentration, this peak becomes broader and the peak height increases. This indicates that the band-edge formation in GaP1-xNx alloys is extremely unique compared to that in conventional semiconductor alloys. © 2003 WILEY-VCH Verlag GmbH & Co. KGaA.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200303430
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DOI ID：10.1002/pssc.200303430, ISSN：1610-1634, ORCID：30384826, SCOPUS ID：33749433192 - Improvement in the luminescence efficiency of GaAsN alloys by photoexcitation
H Yaguchi; T Morioke; T Aoki; Y Hijikata; S Yoshida; H Akiyama; N Usami; D Aoki; K Onabe
5TH INTERNATIONAL CONFERENCE ON NITRIDE SEMICONDUCTORS (ICNS-5), PROCEEDINGS, 巻：0, 号：7, 開始ページ：2782, 終了ページ：2784, 2003年, ［査読有り］
We found that photoexcitation with high excitation power density at low temperatures improves the luminescence efficiency of GaAsN alloys. From the temporal change of the PL intensity, the improvement occurs in a few minutes. Micro Raman study shows that structural changes occur in the laser-irradiated region. These indicate that the improvement of luminescence properties is due to photoexcitation-induced local structural changes. Since no distinct PL peak shift was observed after the laser irradiation at low temperatures, photoexcitation is a useful technique to improve the luminescence efficiency only. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
WILEY-VCH, INC, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1002/pssc.200303514
DOI ID：10.1002/pssc.200303514, ISSN：1862-6351, ORCID：30384825, Web of Science ID：WOS:000189401700190 - Measurements of the depth profile of the refractive indices in oxide films on SiC by spectroscopic ellipsometry
Iida T; Tomioka Y; Yoshimoto K; Midorikawa M; Tukada H; Orihara M; Hijikata Y; Yaguchi H; Yoshikawa M; Itoh H; Ishida Y; Yoshida S
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：41, 号：2 A, 開始ページ：800, 終了ページ：804, 2002年02月, ［査読有り］
The depth profiles of the refractive indices in thermally oxidized films on SiC have been measured by spectroscopic ellipsometry. Oxide films etched at an angle were used to obtain the depth profiles of the refractive indices in the oxide films. The apparent refractive indices napp and thicknesses have been evaluated, assuming that the films have optically uniform single layer structures. The experimental results show that the values of napp increase with oxide film thickness, and approach the values for oxide films on Si at around 60 nm in thickness. This feature is almost the same as the changes of refractive indices of oxide films with oxidation time reported previously. These results reveal that the oxide films are not optically uniform and that the optical properties change with depth from the surface. It has been found that the film structure model where the oxide film is composed of two layers, a thin interface layer around 1 nm in thickness with a higher refractive index than those of SiC and SiO2 and a stoichiometric SiO2 layer, the thickness of which changes with film thickness, can explain the thickness dependence of napp observed. These results suggest that there exists an interface layer with high refractive indices at oxide film/SiC interfaces.
JAPAN SOC APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.41.800
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DOI ID：10.1143/JJAP.41.800, ISSN：0021-4922, ORCID：30384829, SCOPUS ID：0036478462, Web of Science ID：WOS:000176451200070 - Control of macroscopic absorption coefficient of multicrystalline SiGe by microscopic compositional distribution
Usami N; Fujiwara K; Ujihara T; Sazaki G; Yaguchi H; Murakami Y; Nakajima K
Japanese Journal of Applied Physics Part 2-Letters, 巻：41, 号：1 A/B, 開始ページ：L37, 終了ページ：L39, 2002年01月, ［査読有り］
We report on the growth and optical characterizations of multicrystalline SiGe (mc-SiGe) with microscopic compositional distribution for solar cell applications. Mc-SiGe was grown by a simple technique based on the casting method. The compositional distribution and solidification structure of mc-SiGe were found to be strongly dependent on the cooling rate, suggesting that they can be controlled by the growth parameters. Spatial variation of the extinction coefficient, corresponding to the microscopic compositional distribution, was revealed by spectroscopic ellipsometry, and macroscopic optical properties were found to be controlled by the microscopic compositional distribution. The advantage of mc-SiGe was further revealed by the increased absorption in the lower energies compared with uniform SiGe with almost the same average composition.
INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.41.L37
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DOI ID：10.1143/JJAP.41.L37, ISSN：0021-4922, ORCID：30384828, SCOPUS ID：0037082098, Web of Science ID：WOS:000173882600012 - Spatial mapping of the carrier concentration and mobility in SiC wafers by micro fourier-transform infrared spectroscopy
H. Yaguchi; K. Narita; Y. Hijikata; S. Yoshida; S. Nakashima; N. Oyanagi
Materials Science Forum, 巻：389-393, 号：1, 開始ページ：621, 終了ページ：624, 2002年, ［査読有り］
Micro Fourier-transform infrared (FTIR) spectroscopy has been used to investigate the spatial distribution of the carrier concentration and mobility in SiC wafers. The carrier concentration and mobility were independently derived from the reflectance spectra based on the dielectric function taking into account the effect of phonons and plasmons. The carrier concentration profile obtained for an intentionally inhomogeneous N-doped 6H-SiC wafer coincides well with the spatial distribution of color in the wafer. For commercially available wafers, carrier concentrations are found to increase with approaching the center of the wafers. These results demonstrate that micro FTIR is a nondestructive and noncontact technique to spatially characterize the carrier concentration and mobility in SiC wafers. © 2002 Trans Tech Publications.
研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/msf.389-393.621
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DOI ID：10.4028/www.scientific.net/msf.389-393.621, ISSN：0255-5476, eISSN：1662-9752, SCOPUS ID：34247249828 - X-ray photoelectron spectroscopy studies of post-oxidation process effects on oxide/SiC interfaces
Y Hijikata; H Yaguchi; M Yoshikawa; S Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2001, PTS 1 AND 2, PROCEEDINGS, 巻：389-3, 開始ページ：1033, 終了ページ：1036, 2002年, ［査読有り］
In this report, we carried out x-ray photoclectron spectroscopy measurements on slope shaped oxide films to explore the changes of interfacial structures by post oxidation processes. By the observation of Si2p, C1s and O1s spectra, the bonding states which influence the electrical properties of MOS structures were suggested to be bonds related to carbon. We also discuss the reasons for the improvement of MOS properties by these post oxidation processes.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.389-393.1033
DOI ID：10.4028/www.scientific.net/MSF.389-393.1033, ISSN：0255-5476, ORCID：48141540, Web of Science ID：WOS:000177321100249 - Characterization of the interfaces between SiC and oxide films by spectroscopic ellipsometry
Y Tomioka; T Iida; M Midorikawa; H Tukada; K Yoshimoto; Y Hijikata; H Yaguchi; M Yoshikawa; Y Ishida; R Kosugi; S Yoshida
SILICON CARBIDE AND RELATED MATERIALS 2001, PTS 1 AND 2, PROCEEDINGS, 巻：389-3, 開始ページ：1029, 終了ページ：1032, 2002年, ［査読有り］
Spectroscopic ellipsometry has been used to investigate, for the first time, the optical properties of oxide films on SiC to discuss the difference of the structures of SiC/SiO2 interfaces with oxidation processes, thermal oxidation in dry oxygen, pyrogenic oxidation and low temperature deposition of oxides by chemical vapor deposition. It was found that there exist interface layers with high refractive indices between SiC and SiO2, the values of which are larger than those of SiC and SiO2 and depend on the oxidation process. The validity of the evaluation of refractive indices of the interfaces has also been discussed.
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.389-393.1029
DOI ID：10.4028/www.scientific.net/MSF.389-393.1029, ISSN：0255-5476, ORCID：56291595, Web of Science ID：WOS:000177321100248 - Composition analysis of SiO2/SiC interfaces by electron spectroscopic measurements using slope-shaped oxide films
Y Hijikata; H Yaguchi; M Yoshikawa; S Yoshida
APPLIED SURFACE SCIENCE, 巻：184, 号：1-4, 開始ページ：161, 終了ページ：166, 2001年12月, ［査読有り］
We have characterized SiO2/SiC interfaces by X-ray photoelectron spectroscopy in terms of composition and bonds to clarify the reasons for the problems in silicon carbide metal-oxide-semiconductor field-effect-transistor and MOS structures. The oxide films on 6H-SiC were shaped into slopes by HF chemical etching to obtain the depth profile of the composition and the bondings. An interface layer was found near the SiO2/SiC boundary, where SiO2 stoichiometry is collapsed and there exists the bondings other than Si-O-2 and Si-C. Also, we revealed the differences in the interface properties for different oxidation processes. (C) 2001 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0169-4332(01)00491-3
DOI ID：10.1016/S0169-4332(01)00491-3, ISSN：0169-4332, eISSN：1873-5584, CiNii Articles ID：80012788973, ORCID：56291762, Web of Science ID：WOS:000173000100027 - Spectroscopic ellipsometry study on the electronic structure near the absorption edge of GaAsN alloys
Yaguchi H; Matsumoto S; Hijikata Y; Yoshida S; Maeda T; Ogura M; Aoki D; Onabe K
Physica Status Solidi B-Basic Research, 巻：228, 号：1, 開始ページ：269, 終了ページ：272, 2001年11月, ［査読有り］
Spectroscopic ellipsometry has been used to investigate the electronic structure near the fundamental absorption edge of GaAsN alloys grown by metalorganic vapor phase epitaxy. The fundamental absorption edge is clearly observed in the imaginary part of the dielectric function and shifts to lower energies with increasing N concentration. In addition, the absorption structure is observed near the E0 gap energy of GaAs even in GaAsN alloys. This unequivocally shows that the fundamental absorption edge of GaAsN is not shifted from the E0 gap of GaAs but newly formed by the N incorporation. Thus, the formation of the narrowest band gap of GaAsN alloys is found to be completely different from that of conventional compound semiconductor alloys, such as AIGaAs and GaAsP.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/1521-3951(200111)228:1<269::AID-PSSB269>3.0.CO;2-3
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DOI ID：10.1002/1521-3951(200111)228:1<269::AID-PSSB269>3.0.CO;2-3, ISSN：0370-1972, ORCID：30384834, SCOPUS ID：0035541085, Web of Science ID：WOS:000172513100060 - Photoluminescence study on temperature dependence of band gap energy of GaAsN alloys
Yaguchi H; Kikuchi S; Hijikata Y; Yoshida S; Aoki D; Onabe K
Physica Status Solidi B-Basic Research, 巻：228, 号：1, 開始ページ：273, 終了ページ：277, 2001年11月, ［査読有り］
We have studied the temperature dependence of photoluminescence (PL) spectra of GaAsN alloys. The PL peak energy shift due to the temperature change decreases with increasing N concentration of GaAsN alloys. The localized state emission partly contributes to the decrease in the PL peak energy shift. In addition, the small PL peak energy shift at high temperatures is due to the reduction in the temperature dependence of the band gap energy. From the analysis using the Bose-Einstein statistical expression, the average phonon energy is much larger than that expected from the linear interpolation between GaAs and GaN, indicating that the interaction between electrons and phonons localized at N atoms plays an important role in the reduction of the temperature dependence of the band gap energy of GaAsN alloys.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/1521-3951(200111)228:1<273::AID-PSSB273>3.0.CO;2-N
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DOI ID：10.1002/1521-3951(200111)228:1<273::AID-PSSB273>3.0.CO;2-N, ISSN：0370-1972, ORCID：30384833, SCOPUS ID：0035541092, Web of Science ID：WOS:000172513100061 - Temperature dependence of excitonic Gamma(c)-Gamma(v) transition energies GaxIn1-xP crystals
Y Ishitani; H Yaguchi; Y Shiraki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：40, 号：3A, 開始ページ：1183, 終了ページ：1187, 2001年03月, ［査読有り］
The excitonic Gamma (c)-Gamma (v) transition energies of disordered GaxIn1-xP (x = 0.0, 0.52, 0.70, and 1.0) crystals have been measured by photoreflectance (PR) measurements at temperatures from 20 to 300 K. The photoluminescence (PL) peak energy at 20 K is found to be lower than the energy obtained from PR or photoluminescence excitation (PLE) spectra by about 6 meV. The temperature dependence of the transition energy is expressed by a function consisting of several terms, each of which represents the effect of the volume-thermal expansion or the electron-phonon interaction. It is found that the temperature-dependent decrease of the transition energy from the pure electronic transition energy is mainly caused by the electron-phonon interaction. The energy shift due to the electron-phonon interaction increases as the Gap mole fraction increases.
INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.40.1183
DOI ID：10.1143/JJAP.40.1183, ISSN：0021-4922, ORCID：30384835, Web of Science ID：WOS:000170771500006 - Optical characterization of metalorganic vapor-phase epitaxy-grown GaAs1-xNx alloys using spectroscopic ellipsometry
S Matsumoto; H Yaguchi; S Kashiwase; T Hashimoto; S Yoshida; D Aoki; K Onabe
JOURNAL OF CRYSTAL GROWTH, 巻：221, 開始ページ：481, 終了ページ：484, 2000年12月, ［査読有り］
We have measured complex dielectric functions, epsilon (1) + i epsilon (2), of GaAs1-xNx alloys using spectroscopic ellipsometry to investigate higher-energy band gaps. The E-1 gap-related peak height for epsilon (2) decreases with increasing N concentration, indicating that the optical absorption at the E-1 gap decreases. On the contrary, the E-2 gap transition does not change so much with varying N concentration. These results are consistent with the theoretical study, which predicts that the lowest conduction band is mostly a combination of the Gamma and L states. The bowing parameters of the E-1 and E-2 yaps are rather large but much smaller than the bowing parameter of the E-o gap. (C) 2000 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(00)00748-X
DOI ID：10.1016/S0022-0248(00)00748-X, ISSN：0022-0248, CiNii Articles ID：80012169205, ORCID：30384838, Web of Science ID：WOS:000166501400085 - Characterization of oxide films on SiC by spectroscopic ellipsometry
T Iida; Y Tomioka; Y Hijikata; H Yaguchi; M Yoshikawa; Y Ishida; H Okumura; S Yoshida
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 巻：39, 号：10B, 開始ページ：L1054, 終了ページ：L1056, 2000年10月, ［査読有り］
We have, for the first time. evaluated the optical constants of thermally oxidized films on SIC by spectroscopic ellipsometry, and discussed the characteristics of SiC/SiO2 interfaces. It was found that the effective refractive indices are smaller than those of the oxide films on Si. They increase with oxidation time, or oxide thickness, reaching to the values of Si oxides. The refractive indices also depend on the oxidation methods, and the pyrogenic oxidation brings about larger refractive indices than dry oxidation. The origin of the small refractive indices of oxide films on SiC was discussed in terms of interface structures and composition in comparison with those of oxide films on Si.
INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.39.L1054
DOI ID：10.1143/JJAP.39.L1054, ISSN：0021-4922, ORCID：30384836, Web of Science ID：WOS:000090138800014 - Optical properties of cubic GaN grown on 3C-SiC (100) substrates by metalorganic vapor phase epitaxy
Wu J; Yaguchi H; Zhang BP; Segawa Y; Onabe K; Shiraki Y
Physica Status Solidi a-Applied Research, 巻：180, 号：1, 開始ページ：403, 終了ページ：407, 2000年07月, ［査読有り］
Cubic GaN with different low-temperature buffer layers were grown on 3C-SiC (100) substrates by metalorganic vapor phase epitaxy (MOVPE). The sample surface morphology was affected considerably by the thickness of the buffer layer. An X-ray diffraction-peak shift was observed for these samples, indicating the existence of residual strain inside the crystal. The origin of the residual strain can be attributed to the different thermal expansion coefficients of GaN and 3C-SiC. The residual strain has a strong influence on the excitonic transition energies. From the strain dependence of the shift of the exciton peaks, the value of the excitonic bandgap and the strain coefficient (relation between strain parallel to z-axis and exciton energy) of cubic GaN were estimated.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/1521-396X(200007)180:1<403::AID-PSSA403>3.0.CO;2-A
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DOI ID：10.1002/1521-396X(200007)180:1<403::AID-PSSA403>3.0.CO;2-A, ISSN：0031-8965, ORCID：30384840, SCOPUS ID：0034224763, Web of Science ID：WOS:000088605900067 - Fabrication and optical properties of GaAs/AlGaAs quantum dot grown in tetrahedral-shaped recesses on GaAs (111)B substrates by MOVPE
T Tsujikawa; S Mori; H Watanabe; M Yoshita; H Akiyama; R van Dalen; K Onabe; H Yaguchi; Y Shiraki; R Ito
PHYSICA E, 巻：7, 号：3-4, 開始ページ：308, 終了ページ：316, 2000年05月, ［査読有り］
GaAs/AlGaAs quantum dots were grown in tetrahedral-shaped recesses (TSRs) on GaAs ((1) over bar (1) over bar (1) over bar)B substrates at 850 degrees C by metalorganic vapor-phase epitaxy on the bottom ((1) over bar (1) over bar (1) over bar)B regions of the TSRs. As the AlGaAs barrier layer became thicker, a trench-like region comprised of {1 1 (2) over bar} and {(1) over bar (1) over bar 2} vertical sidewalls formed at the bottom region of the TSR. A 780 Angstrom-wide and 96 Angstrom-thick GaAs quantum dot was formed at the bottom of the trench-like region. The luminescence from GaAs layer at only the ((1) over bar (1) over bar (1) over bar)B bottom region of the TSR was confirmed by cathodoluminescence image observation. By micro-photoluminescence observation a narrow line from the bottom region was observed at 1.5511 eV and the luminescence from higher-energy states was observed. The calculation for a 780 Angstrom x 780 Angstrom x 96 Angstrom quantum box revealed that these energy states reflected both the lateral and vertical quantum confinements. (C) 2000 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S1386-9477(99)00331-8
DOI ID：10.1016/S1386-9477(99)00331-8, ISSN：1386-9477, ORCID：56291692, Web of Science ID：WOS:000087358100003 - Second-harmonic generation from GaP/AlP multilayers on GaP (111) substrates based on quasi-phase matching for the fundamental standing wave
M Sato; H Yaguchi; Shoji, I; K Onabe; R Ito; Y Shiraki; S Nakagawa; N Yamada
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 巻：39, 号：4B, 開始ページ：L334, 終了ページ：L336, 2000年04月, ［査読有り］
We have demonstrated second-harmonic generation (SHG) from GaP/AIP multilayers an GaP(111)A substrates based on quasi-phase matching (QPM) for the fundamental standing wave. Theoretical calculation predicted that the SWG power increases with increasing number of GaP/AIP multilayers because of their small absorption coefficient in the spectral range of second-harmonic light, which is in contrast to the case of GaAs/AlAs QPM multilayers. In the transmission SHG measurement using a frequency-tunable Ti:Sapphire laser as a fundamental wave source, maximum SWG power was obtained at a fundamental wavelength of 990 nm from the five-pair GaP/AIP QPM multilayers. The wavelength conversion efficiency was measured to be 9.8 x 10(-10)%/W, which was smaller than the theoretical value of 6.5 x 10(-8)%/W.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.39.L334
DOI ID：10.1143/JJAP.39.L334, ISSN：0021-4922, ORCID：30384841, Web of Science ID：WOS:000088910900003 - Optical constants of cubic GaN, AlN, and AlGaN alloys
Suzuki T; Yaguchi H; Okumura H; Ishida Y; Yoshida S
Japanese Journal of Applied Physics Part 2-Letters, 巻：39, 号：6 A, 開始ページ：L497, 終了ページ：L499, 2000年, ［査読有り］
We have used spectroscopic ellipsometry to investigate, for the first time, the optical constants of cubic GaN, AlN, and AlGaN alloy epitaxial layers grown by molecular beam epitaxy. The refractive indices of cubic AlGaN were found to decrease with increasing Al content, as expected from the empirical observation that the refractive index decreases with increasing direct bandgap energy. In the transparent wavelength region, the refractive indices of cubic AlGaN with lower Al contents are somewhat larger than those of hexagonal modifications, while with higher Al contents, the refractive indices of cubic AlGaN and hexagonal AlGaN are almost equal. We also found that the direct bandgap energies of cubic AlGaN show a parabolic dependence on the Al content.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.39.L497
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DOI ID：10.1143/JJAP.39.L497, ISSN：0021-4922, ORCID：30384839, SCOPUS ID：0033702328, Web of Science ID：WOS:000088911300005 - Time-resolved photoluminescence of cubic GaN grown by metalorganic vapor phase epitaxy
Yaguchi H; Wu J; Akiyama H; Baba M; Onabe K; Shiraki Y
Physica Status Solidi B-Basic Research, 巻：216, 号：1, 開始ページ：237, 終了ページ：240, 1999年11月, ［査読有り］
Time-resolved photoluminescence of high quality cubic GaN was measured to clarify the origin of the emissions observed in cubic GaN. The 3.27 eV emission decay was fast and the intensity decreased with a lifetime of 260 ps at early decay and with a lifetime of 900 ps afterwards. The decay of the 3.18 eV emission was much slower than that of the 3.27 eV emission and the lifetime was 3.8 ns. In time-resolved spectra, the 3.18 eV emission had a broadening on the high-energy side at early times and the peak moved to lower energies with increasing time. These results can be explained in terms of the model for a donor-acceptor pair transition.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/(SICI)1521-3951(199911)216:1<237::AID-PSSB237>3.0.CO;2-O
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DOI ID：10.1002/(SICI)1521-3951(199911)216:1<237::AID-PSSB237>3.0.CO;2-O, ISSN：0370-1972, ORCID：30384850, SCOPUS ID：0033242881, Web of Science ID：WOS:000084193900046 - Substrate misorientation dependence of the hexagonal phase inclusion in cubic GaN films grown by metalorganic vapor phase epitaxy
Nagayama A; Katayama R; Nakadan N; Miwa K; Yaguchi H; Wu J; Onabe K; Shiraki Y
Physica Status Solidi a-Applied Research, 巻：176, 号：1, 開始ページ：513, 終了ページ：517, 1999年11月, ［査読有り］
The metalorganic vapor phase epitaxial (MOVPE) growth of cubic GaN layers on misoriented GaAs (001) substrates, the faces of which were tilted from (001) toward [11̄0] or [110] by 4°, was performed in order to investigate the effect of the substrate misorientation on the inclusion of hexagonal phase in the cubic GaN layer. The sample grown on the tilted surface toward [11̄0] showed an enhanced generation of the hexagonal domain on the (11̄1) face, whereas the hexagonal domain on the (1̄11) face was suppressed. The sample grown on the tilted surface toward [110] showed the generation of the hexagonal domains on both the (11̄1) and (1̄11) faces with an equal magnitude. It is suggested that the generation of hexagonal domains may be suppressed when the exposure of the (11̄1) or (1̄11) faces by the thermal damage of the substrate surface is reduced.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/(SICI)1521-396X(199911)176:1<513::AID-PSSA513>3.0.CO;2-Y
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DOI ID：10.1002/(SICI)1521-396X(199911)176:1<513::AID-PSSA513>3.0.CO;2-Y, ISSN：0031-8965, ORCID：30384849, SCOPUS ID：0033221287, Web of Science ID：WOS:000084032200098 - Selective growth of cubic GaN an patterned GaAs(100) substrates by metalorganic vapor phase epitaxy
J Wu; M Kudo; A Nagayama; H Yaguchi; K Onabe; Y Shiraki
PHYSICA STATUS SOLIDI A-APPLIED RESEARCH, 巻：176, 号：1, 開始ページ：557, 終了ページ：560, 1999年11月, ［査読有り］
Selective growth of cubic GaN on patterned GaAs substrates was studied. The structural and morphological properties of cubic GaN are very dependent on the orientation of the mask stripes. Tn the case of window stripe opening along [011] direction, (111)B facets were clearly observed in all the samples, regardless of the different growth time. Both X-ray diffraction and photoluminescence measurements showed that the hexagonal phase GaN was considerably incorporated in the cubic GaN layer, indicating that the hexagonal GaN is easily constructed along-the (111)B facet. In contrast, window stripes opening along [01-1] direction resulted in the:formation of (311)A facets and subsequently a relatively flat surface occurred as the growth proceeded.-Strong emission peaks of cubic GaN were observed in the photoluminescence spectra.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/(SICI)1521-396X(199911)176:1<557::AID-PSSA557>3.0.CO;2-2
DOI ID：10.1002/(SICI)1521-396X(199911)176:1<557::AID-PSSA557>3.0.CO;2-2, ISSN：0031-8965, ORCID：30384847, Web of Science ID：WOS:000084032200105 - Optical characterization of cubic AlGaN epilayers by cathodoluminescence and spectroscopic ellipsometry
H Okumura; T Koizumi; Y Ishida; H Yaguchi; S Yoshida
PHYSICA STATUS SOLIDI B-BASIC RESEARCH, 巻：216, 号：1, 開始ページ：211, 終了ページ：214, 1999年11月, ［査読有り］
Cubic AlGaN epilayers grown by molecular beam epitaxy were characterized by cathodoluminescence and spectroscopic ellipsometry techniques. The linear increase of the bandgap energy versus Al composition was consistently confirmed by the two techniques, which indicate the direct transition nature of cubic AlGaN band structure. The energy dependence of optical constants for cubic GaN was also obtained by the simulation of the measured allipsometric data.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/(SICI)1521-3951(199911)216:1<211::AID-PSSB211>3.3.CO;2-A
DOI ID：10.1002/(SICI)1521-3951(199911)216:1<211::AID-PSSB211>3.3.CO;2-A, ISSN：0370-1972, ORCID：30384844, Web of Science ID：WOS:000084193900041 - MOVPE growth and luminescence properties of GaAsN alloys with higher nitrogen concentrations
K Onabe; D Aoki; J Wu; H Yaguchi; Y Shiraki
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE, 巻：176, 号：1, 開始ページ：231, 終了ページ：235, 1999年11月, ［査読有り］
Highly luminescent GaAsN alloy films have been successfully obtained with N concentrations up to 3.1% by metalorganic vapor phase epitaxy (MOVPE). The band-gap bowing parameter estimated from the photoluminescence (PL) peak energy is not constant but dependent on the N concentration; 24.0 eV for N < 1% and 17.0 eV for N > 1% at 20 KI and 22.4 eV: for N < 1% and 14.5 eV for N >1% at room temperature. From the characteristic features of the luminescence properties, the: band-edge states are found to be much localized below the conduction band edge, and the emission process at low temperatures is associated with these localized states as in GaPN alloys.
WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1002/(SICI)1521-396X(199911)176:1<231::AID-PSSA231>3.0.CO;2-9
DOI ID：10.1002/(SICI)1521-396X(199911)176:1<231::AID-PSSA231>3.0.CO;2-9, ISSN：1862-6300, eISSN：1862-6319, ORCID：30384843, Web of Science ID：WOS:000084032200044 - Stimulated emission from optically pumped cubic GaN/AlGaN double heterostructures
J. Wu; H. Yaguchi; K. Onabe; Y. Shiraki
Journal of Crystal Growth, 巻：197, 号：1-2, 開始ページ：73, 終了ページ：77, 1999年, ［査読有り］
Cubic GaN/AlGaN heterostructures were grown on semi-insulating GaAs(I 0 0) substrates by metalorganic vaporphase epitaxy. Optical pumping experiments were performed on cubic GaN/AlGaN cavities, which were formed simply by cleaving the substrate. Strong stimulated emission at a wavelength of 394 nm was observed from the cleaved edge of the optically pumped cubic GaN/AlGaN heterostructures at 15 K. The stimulated emission was demonstrated by the superlinear increase of the output intensity and the highly TE-polarized nature. Besides this strong stimulated emission, an additional stimulated emission centered at 383 nm is also observed from some samples. © 1999 Elsevier Science B.V. All rights reserved.
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00945-2
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DOI ID：10.1016/S0022-0248(98)00945-2, ISSN：0022-0248, CiNii Articles ID：80010901748, ORCID：48141822, SCOPUS ID：0033079425 - Photoluminescence study of InP/GaP highly strained quantum wells
T. Kimura; H. Yaguchi; N. Usami; K. Onabe; Y. Shiraki
Institute of Physics Conference Series, 巻：162, 開始ページ：511, 終了ページ：516, 1999年
研究論文（学術雑誌）
ORCID：56291592, Web of Science ID：WOS:000177562700083 - Quantum size effect of lead iodide nanoparticles formed by a Langmuir-Blodgett technique
Tetsuya Yamaki; Keisuke Asai; Kenkichi Ishigure; Kazuhiro Ema; Hiroyuki Yaguchi
Molecular Crystals and Liquid Crystals Science and Technology Section A: Molecular Crystals and Liquid Crystals, 巻：337, 開始ページ：225, 終了ページ：228, 1999年, ［査読有り］
Nanoparticles of lead iodide (PbI2) were prepared by exposure of Langmuir-Blodgett (LB) films of lead arachidate to hydrogen iodide. The photoluminescence (PL) spectrum of the nanoparticles consisted of three bands: an exciton band and two low-energy bands associated with stoichiometric and structural defects. The center of the exciton band was blue-shifted due to a quantum size effect. The PL spectra drastically changed when the temperature increased. © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.
GORDON BREACH SCI PUBL LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1080/10587259908023418
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DOI ID：10.1080/10587259908023418, ISSN：1058-725X, ORCID：56291741, SCOPUS ID：33745440831, Web of Science ID：WOS:000084232500054 - High-temperature metalorganic vapor phase epitaxial growth of GaAs/AlGaAs quantum structures in tetrahedral-shaped recesses on GaAs (111)B substrates
Tsujikawa T; Irisawa T; Yaguchi H; Onabe K; Shiraki Y; Ito R
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：38, 号：1 B, 開始ページ：459, 終了ページ：464, 1999年, ［査読有り］
GaAs/AlGaAs quantum structures were grown in tetrahedral-shaped recesses (TSRs) on GaAs {1̄1̄1̄}B substrates at temperatures above 800°C by metalorganic vapor phase epitaxy because quantum dots were expected to be formed at the bottom {1̄1̄1̄} regions of the TSRs. Observation of cathodoluminescence revealed that GaAs quantum structures with different layer thicknesses were formed at {1̄00} edge regions, {1̄1̄0} and {11̄1̄}A sidewalls and the {1̄1̄1̄} bottom and surface regions of the TSR. Growth on the (1̄1̄1̄)B surface region between TSRs was clearly observed for the sample grown at 850°C. As the growth temperature was raised above 850°C, the photoluminescence intensity on the {1̄1̄1̄}B surface increased whereas that on the {001̄} edge regions and {11̄1̄}A sidewall regions decreased. With an increase in well thickness, the luminescence from the bottom and edge regions was simultaneously observed. A 50 A-thick quantum well was formed on the small bottom region. From scanning electron microscope observation, the lateral size of the region was 550 Å.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.38.459
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DOI ID：10.1143/JJAP.38.459, ISSN：0021-4922, ORCID：30384842, SCOPUS ID：0032621849, Web of Science ID：WOS:000078971100039 - Photoluminescence and photoluminescence-excitation spectroscopy of GaPAsN/GaP lattice-matched multiple quantum well structures
Goshi Biwa; Hiroyuki Yaguchi; Kentaro Onabe; Yasuhiro Shiraki
Journal of Crystal Growth, 巻：195, 号：1-4, 開始ページ：574, 終了ページ：578, 1998年12月, ［査読有り］
GaP1-x-yAsyNx/GaP (x = 2.0%, y = 12%) lattice-matched multiple quantum well (MQW) structures have been grown by metalorganic vapor-phase epitaxy (MOVPE). Low-temperature photoluminescence (PL) and photoluminescence excitation (PLE) measurements for the varied well widths (Lz = 36, 24, and 16 Å) have revealed that the quantum confinement effect to the well manifests itself only in the narrow wells whose width is comparable with or shorter than the spatial extent of the localized excitons. Higher-temperature luminescence has been drastically enhanced, where the room temperature PL intensity is estimated 103-104 times larger than in the bulk. This is due to the efficient electron confinement to the well which is brought about by the large conduction band offset ΔEc (∼280 meV). © 1998 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00734-9
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DOI ID：10.1016/S0022-0248(98)00734-9, ISSN：0022-0248, ORCID：56291728, SCOPUS ID：0032477147, Web of Science ID：WOS:000077839200092 - Micro Raman and micro photoluminescence study of cubic GaN grown on 3C-SiC(0 0 1) substrates by metalorganic vapor phase epitaxy
Hiroyuki Yaguchi; Jun Wu; Baoping Zhang; Yusaburo Segawa; Hiroyuki Nagasawa; Kentaro Onabe; Yasuhiro Shiraki
Journal of Crystal Growth, 巻：195, 号：1-4, 開始ページ：323, 終了ページ：327, 1998年12月, ［査読有り］
We have investigated metalorganic vapor phase epitaxy-grown GaN grains on a 3C-SiC(0 0 1) substrate using micro Raman and micro photoluminescence spectroscopy. Polarized micro Raman spectra clearly showed that horizontal flat facets and inclined facets of the rectangular GaN grains correspond to cubic phase regions and hexagonal phase regions, respectively. To examine the photoluminescence properties of "pure" cubic GaN, micro photoluminescence was performed by focusing a laser beam on the horizontal flat facet. A strong photoluminescence line with the full-width at half-maximum of 5 meV was observed, which is the smallest value to date and shows that the crystal quality of the cubic phase region is excellent. We could clearly identify free exciton, donor bound exciton and acceptor bound exciton emissions in the cubic GaN. © 1998 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00672-1
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DOI ID：10.1016/S0022-0248(98)00672-1, ISSN：0022-0248, ORCID：56291747, SCOPUS ID：0032477174, Web of Science ID：WOS:000077839200055 - Sublattice reversal in GaAs/Si/GaAs (100) heterostructures by molecular beam epitaxy
Koh SJ; Kondo T; Ishiwada T; Iwamoto C; Ichinose H; Yaguchi H; Usami T; Shiraki Y; Ito R
Japanese Journal of Applied Physics Part 2-Letters, 巻：37, 号：12 SUPPL. B, 開始ページ：L1493, 終了ページ：L1496, 1998年12月, ［査読有り］
Sublattice reversal in III-V compound semiconductors grown on group-IV epitaxial layers on III-V substrates has been proposed for fabricating nonlinear optical devices with domain-inverted compound semiconductor structures. Sublattice reversal epitaxy is demonstrated in the GaAs/Si/GaAs (100) system and confirmed by reflection high energy electron diffraction, cross-sectional transmission electron microscopy, anisotropic etching, and optical second-harmonic generation measurements. The present sublattice reversal seems to be assisted by self annihilation of antiphase domains generated at GaAs/Si interfaces.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.37.L1493
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DOI ID：10.1143/JJAP.37.L1493, ISSN：0021-4922, ORCID：30384870, SCOPUS ID：0032295743, Web of Science ID：WOS:000078189800001 - Polarization characteristics of crescent-shaped tensile-strained GaAsP/AlGaAs quantum wire-like lasers (vol 37, pg 1556, 1998)
M Ishikawa; W Pan; Y Kaneko; H Yaguchi; K Onabe; R Ito; Y Shiraki
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：37, 号：7, 開始ページ：4230, 終了ページ：4230, 1998年07月, ［査読有り］
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.37.4230
DOI ID：10.1143/JJAP.37.4230, ISSN：0021-4922, ORCID：30384868, Web of Science ID：WOS:000075363300072 - Theoretical study of conduction band edge formation in GaP
1 - X Nx alloys using a tight-binding approximation
H. Yaguchi
Journal of Crystal Growth, 巻：189-190, 開始ページ：500, 終了ページ：504, 1998年06月, ［査読有り］
The conduction band edge formation in GaP1 - xNx alloys is theoretically studied using a tight-binding method. The electronic structure of GaP1 - xNx ordered alloys whose units-cell size is a × a × na (n = 1-5) is calculated. The calculation confirmed that the conduction band edge formation in Ga1 - xNx alloys originates from the formation of the A line. Localization at the N atoms is also discussed. © 1998 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00339-X
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DOI ID：10.1016/S0022-0248(98)00339-X, ISSN：0022-0248, ORCID：48141882, SCOPUS ID：0032090874, Web of Science ID：WOS:000074730400102 - Temperature dependence of photoluminescence of GaP
1-x Nx alloys
Hiroyuki Yaguchi; Goshi Biwa; Seiro Miyoshi; Daiichiro Aoki; Keisuke Arimoto; Kentaro Onabe; Ryoichi Ito; Yasuhiro Shiraki
Journal of Crystal Growth, 巻：189-190, 開始ページ：496, 終了ページ：499, 1998年06月, ［査読有り］
We report on the temperature dependence of photoluminescence (PL) in GaP1-xNx alloys. With increasing temperature the feature of the PL spectrum changes considerably and the luminescence with lower energies becomes predominant. This is explained by thermal activation processes from localized states to the state where excitons can move freely. By estimating the activation energies from the temperature dependence of the PL intensity, it is found that the state where excitons can move freely is formed below the band edge of GaP and shifts to lower energies with increasing nitrogen content. This state is considered to originate from the isoelectronic trap due to isolated nitrogens in GaP (A line) and correspond to the band edge of the GaP1-xNx alloy system. © 1998 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00338-8
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DOI ID：10.1016/S0022-0248(98)00338-8, ISSN：0022-0248, ORCID：30384871, SCOPUS ID：0032092389, Web of Science ID：WOS:000074730400101 - Metalorganic vapor-phase epitaxy of GaP
1-x-y Asy Nx quaternary alloys on GaP
Goshi Biwa; Hiroyuki Yaguchi; Kentaro Onabe; Yasuhiro Shiraki
Journal of Crystal Growth, 巻：189-190, 開始ページ：485, 終了ページ：489, 1998年06月, ［査読有り］
We report on a successful growth of GaP1-x-yAsyNx quaternary alloys on GaP by metalorganic vapor-phase epitaxy (MOVPE). The arsenic solid composition increases with increasing AsH3 supply during the MOVPE growth, while the nitrogen composition is unchanged. The alloys with compositions (x ∼ 2.3%, 0 < y < 19%) are obtained, and the control of the lattice constant in GaP1-x-yAsyNx quaternary alloys is demonstrated. From the dependence of photoluminescence (PL) intensities on lattice mismatch to GaP substrates, we found that lattice-matching to substrates is necessary to obtain GaP1-x-yAsyNx alloys with high quality and intense PL. © 1998 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00336-4
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DOI ID：10.1016/S0022-0248(98)00336-4, ISSN：0022-0248, ORCID：48141583, SCOPUS ID：0032089854, Web of Science ID：WOS:000074730400099 - Investigation of luminescence properties of GaN single crystals grown on 3C-SiC substrates
J. Wu; H. Yaguchi; H. Nagasawa; Y. Yamaguchi; K. Onabe; Y. Shiraki; R. Ito
Journal of Crystal Growth, 巻：189-190, 開始ページ：420, 終了ページ：424, 1998年06月, ［査読有り］
Cathodoluminescence (CL) and photoluminescence (PL) investigations of single crystal GaN grown on 3C-SiC(1 0 0) substrates by metalorganic vapor-phase epitaxy are reported. The GaN grown on 3C-SiC substrates shows distinct crystal facets. We identified the square facet and inclined facet as cubic GaN and hexagonal GaN, respectively. We studied the luminescence properties from the square facet or from the inclined facets separately by CL. For the cubic GaN, a sharp excitonic transition and a weak DA pair transition were observed from the square facet. On the other hand, an emission line at 3.293 eV was obtained from the inclined facets. By studying its temperature dependence, we suggest that the 3.293 eV emission is due to the free electron to acceptor transition of hexagonal GaN. © 1998 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00312-1
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DOI ID：10.1016/S0022-0248(98)00312-1, ISSN：0022-0248, eISSN：1873-5002, ORCID：30384857, SCOPUS ID：0032092034, Web of Science ID：WOS:000074730400085 - Optical transitions in cubic GaN grown on GaAs(1 0 0) substrates by metalorganic vapor-phase epitaxy
Jun Wu; Hiroyuki Yaguchi; Kentaro Onabe; Ryoichi Ito; Yasuhiro Shiraki
Journal of Crystal Growth, 巻：189-190, 開始ページ：415, 終了ページ：419, 1998年06月, ［査読有り］
We investigated the optical transitions in cubic GaN films grown on GaAs(1 0 0) substrates by metalorganic vapor-phase epitaxy. The cubic GaN films show good optical quality. From temperature and excitation intensity dependence, the emission lines at 3.274 and 3.178 eV were assigned to the excitonic transition and the donor-acceptor pair transition, respectively. We also suggested an additional acceptor level (EA′ ≈ 212 meV) to explain the origin of the emission lines at 3.088 and 3.056 eV, on the basis of the excitation intensity dependence. © 1998 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00311-X
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DOI ID：10.1016/S0022-0248(98)00311-X, ISSN：0022-0248, eISSN：1873-5002, ORCID：56291665, SCOPUS ID：0032093256, Web of Science ID：WOS:000074730400084 - Fabrication of Pb(Zr,Ti)O
3 /MgO/GaN/GaAs structure for optoelectronic device applications
Atsushi Masuda; Shinya Morita; Hideki Shigeno; Akiharu Morimoto; Tatsuo Shimizu; Jun Wu; Hiroyuki Yaguchi; Kentaro Onabe
Journal of Crystal Growth, 巻：189-190, 開始ページ：227, 終了ページ：230, 1998年06月, ［査読有り］
Pb(Zr,Ti)O3 (PZT) films were deposited on cubic GaN/(1 0 0)GaAs for the first time with or without MgO buffer layer by pulsed laser ablation. MgO films were grown on cubic GaN with cube-on-cube epitaxy. It was found that MgO buffer layer is very useful for suppressing the diffusion of O and metal elements into GaN layer. Preferentially [1 0 0]-oriented perovskite PZT films were obtained on cubic GaN with MgO buffer layer although randomly oriented perovskite PZT films were obtained without MgO buffer layer. PZT/MgO/GaN structure is one of the promising candidates for integrated devices composed of ferroelectric waveguides and blue laser diodes. © 1998 Elsevier Science B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(98)00241-3
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DOI ID：10.1016/S0022-0248(98)00241-3, ISSN：0022-0248, eISSN：1873-5002, ORCID：56291701, SCOPUS ID：0032092953, Web of Science ID：WOS:000074730400048 - Characterization of SiGe strained heterostructures grown by molecular beam epitaxy using a Si effusion cell
H. Yaguchi; T. Yamamoto; Y. Shiraki
Thin Solid Films, 巻：321, 号：1-2, 開始ページ：241, 終了ページ：244, 1998年05月, ［査読有り］
We characterize SiGe strained heterostructures grown by molecular beam epitaxy (MBE) using a Si effusion cell which can be used at high temperatures up to 1700°C instead of an electron beam gun conventionally used in solid-source Si MBE. Photoluminescence is clearly observed from a Si/SiGe quantum well grown on a Si(001) substrate using the Si effusion cell. This indicates that the sample grown with the Si effusion cell is of good quality. It is found from X-ray diffraction measurement of a Ge/Si strained-layer superlattice grown on a Ge(001) substrate that good controllability of the growth rate can be realized by using the Si effusion cell. Optical transitions observed in the photoreflectance spectrum of the Ge/Si strained layer superlattice agree with the Kronig-Penny model calculation taking account of the non-parabolicity of the conduction band. © 1998 Elsevier Science S.A. All rights reserved.
ELSEVIER SCIENCE SA, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0040-6090(98)00480-5
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DOI ID：10.1016/S0040-6090(98)00480-5, ISSN：0040-6090, CiNii Articles ID：80010404794, ORCID：48141850, SCOPUS ID：0347537655, Web of Science ID：WOS:000074745700044 - Polarization characteristics of crescent-shaped tensile-strained GaAsP/AlGaAs quantum wire-like lasers
Ishikawa M; Pan WG; Kaneko Y; Yaguchi H; Onabe K; Ito R; Shiraki Y
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：37, 号：3 SUPPL. B, 開始ページ：1556, 終了ページ：1558, 1998年03月, ［査読有り］
Crescent-shaped tensile-strained GaAsP/AlGaAs quantum wire-like lasers are fabricated on V-grooved GaAs(100) substrates by mctalorganic vapor phase epitaxy. Light-output versus current characteristics, polarized lasing spectra and near-field patterns show lasing from the quantum wires in the TM mode. The threshold current density per wire is as low as 500 A/cm2 and the lasing wavelength is 780 nm.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.37.1556
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DOI ID：10.1143/JJAP.37.1556, ISSN：0021-4922, ORCID：30384867, SCOPUS ID：0344002874, Web of Science ID：WOS:000073664900113 - Metalorganic vapor phase epitaxy growth of high quality cubic GaN on GaAs (100) substrates
Wu J; Yaguchi H; Onabe K; Shiraki Y; Ito R
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：37, 号：3 SUPPL. B, 開始ページ：1440, 終了ページ：1442, 1998年03月, ［査読有り］
We report on the growth of high quality cubic GaN films on GaAs (100) substrates by low pressure metalorganic vapor phase epitaxy. The GaN films exhibit a smooth surface which is free from cracks. X-ray diffraction shows the cubic nature of the GaN films. X-ray rocking curve with ω scan shows that the crystal quality of GaN films improves markedly with increasing growth temperatures. Photoluminescence measurements confirm the high quality of the cubic GaN films. The full width at half maximum of excitonic emission from the cubic GaN films is as narrow as 70meV at 300K.
JAPAN SOC APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.37.1440
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DOI ID：10.1143/JJAP.37.1440, ISSN：0021-4922, ORCID：30384859, SCOPUS ID：0009207272, Web of Science ID：WOS:000073664900089 - GaAs/AlGaAs quantum structures grown in tetrahedral-shaped recesses on GaAs (111)B substrates by metalorganic vapor phase epitaxy
Tsujikawa T; Momma K; Yaguchi H; Onabe K; Shiraki Y; Ito R
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：37, 号：3 SUPPL. B, 開始ページ：1493, 終了ページ：1496, 1998年03月, ［査読有り］
GaAs/AlGaAs quantum structures were grown in tetrahedral-shaped recesses (TSRs) on GaAs (111)B substrates at different growth rates by metalorganic vapor phase epitaxy. Observation of cathodoluminescence revealed that GaAs quantum structures with different layer thicknesses were formed at {100} edge regions, {110} and {111} A sidewalls and the {111} bottom region of the TSR. The luminescence from the bottom region of the TSRs was clearly seen in the sample grown at a large growth rate. With increasing growth rate, the thickness in the bottom region increased, whereas the thickness at the edge regions decreased. This is explained by a reduction in the migration distance of Ga adatoms from the {111} bottom region to the other regions.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.37.1493
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DOI ID：10.1143/JJAP.37.1493, ISSN：0021-4922, ORCID：30384856, SCOPUS ID：0043230458, Web of Science ID：WOS:000073664900101 - Self-assembled, very long II-VI semiconductor quantum wires
B. P. Zhang; W. X. Wang; T. Yasuda; Y. Segawa; H. Yaguchi; K. Onabe; K. Edamatsu; T. Itoh
Materials Science and Engineering B, 巻：51, 号：1-3, 開始ページ：224, 終了ページ：228, 1998年02月, ［査読有り］
Self-organized ZnCdSe quantum wires (QWRs) are realized on cleavage-induced GaAs (110) surfaces based on simultaneous selective growth and composition modulation. Formed on step tops, the QWRs are parallel to the [1̄10] direction and extend to millimeter order in length. Surface observations and optical studies demonstrate the formation of QWRs. A large piezo-electric field is observed in the QWRs, implying potential applications in nonlinear optoelectronic devices. © 1998 Elsevier Science S.A. All rights reserved.
ELSEVIER SCIENCE SA, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0921-5107(97)00265-1
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DOI ID：10.1016/S0921-5107(97)00265-1, ISSN：0921-5107, ORCID：30384869, SCOPUS ID：0342391357, Web of Science ID：WOS:000072728800048 - Molecular beam epitaxy of SiGe heterostructures using a newly designed Si effusion cell
H. Yaguchi; T. Yamamoto; Y. Shiraki
Materials Science and Engineering B, 巻：51, 号：1-3, 開始ページ：170, 終了ページ：172, 1998年02月, ［査読有り］
We demonstrate the usefulness of a newly designed Si effusion cell which can be used at high temperatures up to 1700°C instead of a conventional electron beam evaporator in solid-source Si molecular beam epitaxy. The growth rate ranges from 0.005 to 0.5 Å s-1 at temperatures from 1350 to 1650°C and agrees well with the temperature dependence of the Si vapor pressure. Photoluminescence was observed from a Si/SiGe quantum well grown on a Si substrate using the Si effusion cell. This indicates that the sample has little defects or dislocations which may result in nonradiative recombination centers or deep levels. It is found from photoreflectance and X-ray diffraction measurements that excellent controllability of the growth rate can be realized by using the Si effusion cell. © 1998 Elsevier Science S.A. All rights reserved.
ELSEVIER SCIENCE SA, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0921-5107(97)00254-7
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DOI ID：10.1016/S0921-5107(97)00254-7, ISSN：0921-5107, ORCID：48141848, SCOPUS ID：0347486931, Web of Science ID：WOS:000072728800037 - A new approach to ZnCdSe quantum dots
B. P. Zhang; T. Yasuda; W. X. Wang; Y. Segawa; K. Edamatsu; T. Itoh; H. Yaguchi; K. Onabe
Materials Science and Engineering B, 巻：51, 号：1-3, 開始ページ：127, 終了ページ：131, 1998年02月, ［査読有り］
We propose a new approach of fabricating ZnCdSe quantum dots (QDs) on ZnSe and GaAs (110) surfaces by simply depositing a ZnSe/ZnCdSe/ZnSe heterostructure. The growth conditions are selected to introduce surface roughness on the over grown ZnSe which allows the formation of ZnCdSe QDs. Optical studies unambiguously demonstrate the formation of QDs. Resolution-limited sharp emission lines are observed by micro-photoluminescences and the linewidths are much less than the thermal energy. As time goes on, intermittent behaviors of the QD emissions are observed. A proper selection of growth conditions is essential in obtaining ZnCdSe QDs by this method, especially on GaAs (110) surfaces. © 1998 Elsevier Science S.A. All rights reserved.
ELSEVIER SCIENCE SA, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0921-5107(97)00245-6
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DOI ID：10.1016/S0921-5107(97)00245-6, ISSN：0921-5107, ORCID：56291699, SCOPUS ID：0031997271, Web of Science ID：WOS:000072728800028 - Exciton diffusion dynamics in quantum nanostructures on V-groove patterned substrates
N. Usami; Y. Shiraki; W. Pan; H. Yaguchi; K. Onabe
Superlattices and Microstructures, 巻：23, 号：2, 開始ページ：395, 終了ページ：400, 1998年, ［査読有り］
Time-resolved photoluminescence (PL) measurements were performed for two different quantum nanostructures on V-groove patterned substrates; SiGe/Si quantum wells (QWs) on V-grooved Si substrates and AlGaAs spontaneous vertical quantum wells on V-grooved GaAs substrates. Anomalous behaviours of the PL, such as the decrease of the decay time of the SiGe (111) QWs and the (111)A AlGaAs layer, were fully explained by taking the exciton diffusion towards the bottom of the V-groove into account, showing that the exciton diffusion driven by the spatial nonuniformity of the alloy compositions and/or geometry of the substrates is a key to controlling the PL properties of the nanostructures. © 1998 Academic Press Limited.
ACADEMIC PRESS LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1006/spmi.1996.0285
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DOI ID：10.1006/spmi.1996.0285, ISSN：0749-6036, CiNii Articles ID：80010189221, ORCID：56291662, SCOPUS ID：11544283825, Web of Science ID：WOS:000072396800032 - Cleaved cavity stimulated emission from an optically pumped cubic GaN/AlGaN heterostructure grown on GaAs (100) substrate
J. Wu; H. Yaguchi; K. Onabe; Y. Shiraki
Applied Physics Letters, 巻：73, 号：14, 開始ページ：1931, 終了ページ：1933, 1998年, ［査読有り］
Cubic GaN/AlGaN double heterostructure was grown on semi-insulating GaAs (100) substrate by metalorganic vapor phase epitaxy. Strong stimulated emission was observed from the cleaved edge of the optically pumped cubic GaN/AlGaN heterostructure at 15 K. The cavity was formed simply by cleaving the substrate. The stimulated emission was demonstrated by the superlinear increase of the output intensity and the highly transverse electric polarized nature. The stimulated emission showed an obvious redshift compared with the spontaneous one. © 1998 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.122326
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DOI ID：10.1063/1.122326, ISSN：0003-6951, CiNii Articles ID：80010580213, ORCID：56291775, SCOPUS ID：0032487237, Web of Science ID：WOS:000076183300003 - カソ-ドルミネツセンスによる半導体低次元構造の評価 (日本電子顕微鏡学会第43回シンポジウム論文集--21世紀へ向けての新技術の展開--平成10年10月28日(水)〜30日(金),千葉大学けやき会館〔含 著者名索引〕) -- (ワ-クショップ カソ-ドルミネッセンスを使った機能評価法の発展)
矢口 裕之; 辻川 智子; 尾鍋 研太郎
電子顕微鏡, 巻：33, 号：2, 開始ページ：217, 終了ページ：220, 1998年
日本顕微鏡学会, 日本語
ISSN：0417-0326, CiNii Articles ID：40002545376, CiNii Books ID：AN00145000 - Metalorganic vapor phase epitaxy growth and photoluminescence properties of cubic AlxGa1-xN
Wu J; Yaguchi H; Onabe K; Shiraki Y
Applied Physics Letters, 巻：73, 号：2, 開始ページ：193, 終了ページ：195, 1998年, ［査読有り］
We have grown cubic AlxGa1-xN (0
DOI：https://doi.org/10.1063/1.121752
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DOI ID：10.1063/1.121752, ISSN：0003-6951, ORCID：30384858, SCOPUS ID：0000148788, Web of Science ID：WOS:000075275400021 - The optical process in AlInP/GaInP/AlInP quantum wells (vol 80, pg 4592, 1996)
Y Ishitani; S Minagawa; T Kita; T Nishino; H Yaguchi; Y Shiraki
JOURNAL OF APPLIED PHYSICS, 巻：82, 号：11, 開始ページ：5876, 終了ページ：5876, 1997年12月, ［査読有り］
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.366457
DOI ID：10.1063/1.366457, ISSN：0021-8979, ORCID：30384885, Web of Science ID：WOS:A1997YH59000089 - Growth mechanism in the metalorganic vapor phase epitaxy of metastable GaP1-xNx alloys: A growth interruption study
Miyoshi S; Yaguchi H; Onabe K; Shiraki Y; Ito R
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：36, 号：12 A, 開始ページ：7110, 終了ページ：7118, 1997年12月, ［査読有り］
The metalorganic vapor phase epitaxy (MOVPE) of metastable GaP1-xNx alloys applying a growth interruption technique is performed. In the growth procedure, different from conventional MOVPE, a cycle of 1 ML growth and growth interruption (Ga precursor supply is turned off) is repeated. The nitrogen content (x) decreases with the increasing growth interruption time due to the desorption of nitrogen during the interruption. This means that the solid composition of the alloy is determined by the competition between the supply and the desorption of nitrogen at the film surface. The nitrogen adsorption/desorption model is presented. The time constant of the nitrogen desorption is obtained to be 0.47s at 670°C. It is clarified that in the conventional (without growth interruption) MOVPE of the alloys, low growth temperature and high growth rate decrease the nitrogen desorption from the film surface and thus result in a large nitrogen content. We succeeded in growing the alloys with x as large as 6.3% by using a low growth temperature (650°C) and a high growth rate (5 MLs/s).
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.36.7110
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DOI ID：10.1143/JJAP.36.7110, ISSN：0021-4922, ORCID：30384876, SCOPUS ID：0031376350, Web of Science ID：WOS:000071543500005 - Self formation and optical properties of II-VI semiconductor wire structures
Zhang BP; Wang WX; Yasuda T; Li YQ; Segawa Y; Yaguchi H; Onabe K; Edamatsu K; Itoh T
Japanese Journal of Applied Physics Part 2-Letters, 巻：36, 号：11 SUPPL. B, 開始ページ：L1490, 終了ページ：L1493, 1997年11月, ［査読有り］
Based on simultaneous selective growth and composition modulation, Zn1-xCdxSe wire structures are spontaneously formed on cleavage-induced GaAs (110) surfaces by deposition of a Zn1-yCdySe (x > y) alloy layer. The wire structures are formed on the top edge of the steps introduced by cleavage. These wires show a strongly polarized emission and a large piezoelectric effect, implying a potential for applications in nonlinear optoelectronic devices. This paper discusses a novel approach to semiconductor nanostructures.
JAPAN SOC APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.36.L1490
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DOI ID：10.1143/JJAP.36.L1490, ISSN：0021-4922, ORCID：30384883, SCOPUS ID：0031276855, Web of Science ID：WOS:A1997YJ04500005 - The Gamma(c)-Gamma(v) transition energies of AlxIn1-xP alloys
Ishitani Y; Hamada H; Minagawa S; Yaguchi H; Shiraki Y
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：36, 号：11, 開始ページ：6607, 終了ページ：6613, 1997年11月, ［査読有り］
The transition energies at 20 K for the Gamma(6c)-Gamma(7v) (electron-heavy hole). (E-s(hh)(x)) and for the Gamma(6c)-Gamma(6v(I)) (electron-light hole) (E-s(lb)(x)) of strained and disordered AlxIn1-xP (0.43 less than or equal to x less than or equal to 0.62) on GaAs substrates were measured using a photoreflectance method. They are expressed as E-s(hh)((x)) = 1.488(+/-0.020) + 2.30(+/-0.04).x, and E-s(lh)(x) = 1.738(+/-0.030) + 1.81(+/-0.06).x(eV). The Gamma(6c)-Gamma(8v) transition energies for unstrained layers (E,(ar)) were also measured at 20 K as Eu (x) = 1.418(+/- 0.007) + 2.42 (+/- 0.01).x(eV). The unstrained samples were InP, Al0.53In0.47P on a GaAs substrate and Al0.73In0.27P On it GaAs0.61P0.39 substrate. The shift of the transition energies due to stress was obtained from these transition energies. The hydrostatic and shear deformation potentials for AlxIn1-xP alloys were calculated to be -5.23(+/-0.60)eV and -1.67(+/-0.26) eV by comparing the experimental results and the theoretical formulae.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.36.6607
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DOI ID：10.1143/JJAP.36.6607, ISSN：0021-4922, ORCID：30384884, SCOPUS ID：0031277384, Web of Science ID：WOS:000071172300005 - Electronic structure of (111)-GaAsP/AlGaAs strained-layer quantum wells
Xiong Zhang; Mitsuteru Ishikawa; Hiroyuki Yaguchi; Kentaro Onabe
Surface Science, 巻：387, 号：1-3, 開始ページ：371, 終了ページ：382, 1997年10月, ［査読有り］
The GaAs1-xPx/AlyGa1-yAs (x = 0.07-0.14, y = 0.3) strained-layer multiple quantum wells grown by metal-organic vapor phase epitaxy on GaAs-(111)B substrates have been characterized by X-ray diffraction and photoreflectance (PR) spectroscopy. By fitting the experimental results with the calculation which was based on the deformation potential theory modified by the strain-induced piezoelectric field, the energy band offset ratio for the conduction band at the heterointerface of GaAs1-xPx/AlyGa1-yAs was quantitatively determined to be Qc = 0.61 ± 0.03. This value was found to be nearly independent of the phosphorous composition x in the whole region that has been investigated in this study. Moreover, several anomalous phenomena observed with the PR measurement as well as the possible physical origins have also been discussed. © 1997 Elsevier Science B.V.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0039-6028(97)00401-9
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DOI ID：10.1016/S0039-6028(97)00401-9, ISSN：0039-6028, CiNii Articles ID：80009902754, ORCID：48141594, SCOPUS ID：0031560008, Web of Science ID：WOS:A1997YC84800043 - Photoluminescence properties of cubic GaN grown on GaAs(100) substrates by metalorganic vapor phase epitaxy
J Wu; H Yaguchi; K Onabe; R Ito; Y Shiraki
APPLIED PHYSICS LETTERS, 巻：71, 号：15, 開始ページ：2067, 終了ページ：2069, 1997年10月, ［査読有り］
Photoluminescence (PL) measurements were performed on cubic GaN films grown on GaAs(100) substrates by metalorganic vapor phase epitaxy. The cubic GaN films show a high optical quality that enables us to study the PL spectra in detail. From temperature and excitation intensity dependence, the emission lines at 3.274 and at 3.178 eV were assigned to the excitonic transition and the donor-acceptor pair transition, respectively. We also observed two additional emission lines at 3.088 and 3.056 eV. An excitonic emission at 3.216 eV with full width half maximum value as small as 73 meV was observed at 300 K. (C) 1997 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.119344
DOI ID：10.1063/1.119344, ISSN：0003-6951, ORCID：30384882, Web of Science ID：WOS:A1997YA20900003 - Crystal structure of GaN grown on 3C-SiC substrates by metalorganic vapor phase epitaxy
Wu J; Yaguchi H; Nagasawa H; Yamaguchi Y; Onabe K; Shiraki Y; Ito R
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：36, 号：7 A, 開始ページ：4241, 終了ページ：4245, 1997年07月, ［査読有り］
GaN films were grown on 3C-SiC substrates by metalorganic vapor phase epitaxy (MOVPE) using 1,1-dimethylhydrazine (DMHy) as the N source. The crystal structure was strongly affected by both the growth temperature and the V/III ratio. At 600°C, only hexagonal GaN films with their c-axis perpendicular to the substrate surface were grown. At 80°C, relatively high V/III ratios resulted in the growth of hexagonal GaN with their c-axis oriented in the [111] direction while cubic GaN films were obtained at lower V/III ratios. The origin of [111]-oriented hexagonal GaN is also discussed.
JAPAN SOC APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.36.4241
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DOI ID：10.1143/JJAP.36.4241, ISSN：0021-4922, ORCID：30384874, SCOPUS ID：0031189839, Web of Science ID：WOS:A1997XR22300004 - Metalorganic vapor phase epitaxy growth features of AlGaAs in tetrahedral-shaped recesses on GaAs (111)B substrates
Tsujikawa T; Pan WG; Momma K; Kudo M; Tanaka K; Yaguchi H; Onabe K; Shiraki Y; Ito R
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：36, 号：6 SUPPL. B, 開始ページ：4102, 終了ページ：4106, 1997年06月, ［査読有り］
We have investigated the compositional modulation of AlGaAs layers grown in tetrahedral-shaped recesses (TSRs) on n-type GaAs (111)B substrates using scanning electron microscopy, photoluminescence and cathodoluminescence. Growth hardly occurred between the TSRs, and complicated facets were seen in the TSR. Gallium-rich regions were formed around the edges between sidewalls rather than at the center of sidewalls and at the bottom region rather than the top region. To observe the facetting process during growth, GaAs/AlGaAs multilayers were also grown in TSRs. Aluminum compositional modulation is dependent not only on the difference in migration distances of Ga and Al atoms but also on the differences in the incorporating process among different facets.
JAPAN SOC APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.36.4102
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DOI ID：10.1143/JJAP.36.4102, ISSN：0021-4922, ORCID：30384878, SCOPUS ID：0043230459, Web of Science ID：WOS:000073628300074 - Naturally formed ZnCdSe quantum dots on ZnSe (110) surfaces
BP Zhang; T Yasuda; Y Segawa; H Yaguchi; K Onabe; E Edamatsu; T Itoh
APPLIED PHYSICS LETTERS, 巻：70, 号：18, 開始ページ：2413, 終了ページ：2415, 1997年05月, ［査読有り］
We successfully realized ZnCdSe quantum dots on a cleavage-induced ZnSe (110) surface by depositing a ZnSe/ZnCdSe/ZnSe heterostructure under growth conditions that cannot lead to layer-by-layer growth of ZnSe. This growth mode introduces surface roughness to the newly deposited ZnSe layer, and ZnCdSe quantum dots are then formed. Cathodoluminescence and microphotoluminescence measurements demonstrate the formation of quantum dots. (C) 1997 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.118888
DOI ID：10.1063/1.118888, ISSN：0003-6951, ORCID：30384879, Web of Science ID：WOS:A1997WZ07600027 - Nitrogen concentration dependence of photoluminescence decay time in GaP
1-x Nx alloys
Hiroyuki Yaguchi; Seiro Miyoshi; Hideo Arimoto; Shiro Saito; Hidefumi Akiyama; Kentaro Onabe; Yasuhiro Shiraki; Ryoichi Ito
Solid-State Electronics, 巻：41, 号：2 SPEC. ISS., 開始ページ：231, 終了ページ：233, 1997年02月, ［査読有り］
We report on the nitrogen concentration dependence of photoluminescence (PL) properties in GaP1-xNx alloys. Time-resolved PL measurements reveal that the radiative transition and relaxation processes in GaP1-zNx alloys with high nitrogen concentrations are significantly different from those with low concentrations where NNi lines are clearly observed. The PL decay profile shows two distinct exponential processes with fast and slow decay times for high concentrations. With increasing N concentration, the fast decay component becomes dominant and the slow decay time becomes longer. The fast decay is attributed to the relaxation to nonradiative recombination centers. The slow decay indicates the long radiative lifetime due to the weak localization of excitons and the slow relaxation due to the scattered spatial distribution of the states. This is consistent with the fact that the PL occurs at the tails of the density of states. © 1997 Elsevier Science Ltd.
PERGAMON-ELSEVIER SCIENCE LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0038-1101(96)00206-7
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DOI ID：10.1016/S0038-1101(96)00206-7, ISSN：0038-1101, CiNii Articles ID：80009442419, ORCID：56291672, SCOPUS ID：0031076173, Web of Science ID：WOS:A1997WF76300024 - Photoluminescence excitation spectroscopy of GaP
1 - X Nx alloys: Conduction-band-edge formation by nitrogen incorporation
Hiroyuki Yaguchi; Seiro Miyoshi; Goshi Biwa; Masaya Kibune; Kentaro Onabe; Yasuhiro Shiraki; Ryoichi Ito
Journal of Crystal Growth, 巻：170, 号：1-4, 開始ページ：353, 終了ページ：356, 1997年01月, ［査読有り］
We have investigated the conduction-band-edge formation in GaP1 - xNx alloys by nitrogen incorporation into GaP using photoluminescence excitation (PLE) spectroscopy. The PLE spectra of GaP1 - xNx alloys with various nitrogen concentrations show that the absorption edge shifts to lower energies with increasing nitrogen concentration. From the nitrogen concentration dependence of the absorption edge energy we found that the conduction-band-edge formation in GaP1 - xNx alloys originates from the formation of the A line.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(96)00592-1
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DOI ID：10.1016/S0022-0248(96)00592-1, ISSN：0022-0248, CiNii Articles ID：80009462734, ORCID：56291666, SCOPUS ID：0030680373, Web of Science ID：WOS:A1997WD06200066 - In-plane polarization properties of GaAsP/AlAs strained quantum wells on GaAs(113)A and (114)A substrates
N. Hiroyasu; H. Yaguchi; K. Onabe; Y. Shiraki; R. Ito
Institute of Physics Conference Series, 巻：155, 開始ページ：771, 終了ページ：774, 1997年
研究論文（学術雑誌）
ORCID：56291697, Web of Science ID：WOS:A1997BJ12N00181 - A highly luminescent crescent-shaped tensile-strained GaAsP/AlGaAs quantum wire laser structure
Wugen Pan; Hiroyuki Yaguchi; Yoshihiko Hanamaki; Mitsuteru Ishikawa; Yasuhisa Kaneko; Kentaro Onabe; Ryoichi Ito; Yasuhiro Shiraki
Journal of Crystal Growth, 巻：170, 号：1-4, 開始ページ：585, 終了ページ：589, 1997年01月, ［査読有り］
We report a highly luminescent crescent-shaped tensile-strained GaAsP/AlGaAs quantum wire (QWR) laser structure on 3 μm periodic V-grooves grown by low-pressure (100 Torr) metalorganic vapor phase epitaxy (MOVPE). Photoluminescence studies show that carriers are efficiently captured from neighboring quantum well layers (QWLs) into QWRs, which give efficient luminescence. The QWR light emitting diode (LED) shows polarization insensitivity resulting from the tensile strain properties of the QWR structure.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0022-0248(96)00593-3
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DOI ID：10.1016/S0022-0248(96)00593-3, ISSN：0022-0248, CiNii Articles ID：80009462781, ORCID：56291746, SCOPUS ID：0030687245, Web of Science ID：WOS:A1997WD06200113 - Self Formation and Photoluminescence of II-VI Quantum Wires on GaAs(110) Surfaces
B. P. Zhang; W. X. Wang; G. Isoya; T. Yasuda; Y. Segawa; H. Yaguchi; K. Onabe; K. Edamatsu; T. Itoh
Nonlinear Optics, 巻：18, 号：2-4, 開始ページ：133, 終了ページ：136, 1997年
研究論文（学術雑誌）
ORCID：48141781, SCOPUS ID：0031347795 - MOVPE Growth of GaPAsN Quaternary Alloys Lattice-Matched to GaP
Goshi Biwa; Hiroyuki Yaguchi; Kentaro Onabe; Yasuhiro Shiraki
MRS Proceedings, 巻：482, 1997年01月
Cambridge University Press ({CUP}), 研究論文（学術雑誌）
DOI：https://doi.org/10.1557/proc-482-173
DOI ID：10.1557/proc-482-173, ISSN：1946-4274, ORCID：48141416, SCOPUS ID：0031389252, Web of Science ID：WOS:000073983100026 - The optical processes in AlInP/GaInP/AlInP quantum wells
Y Ishitani; S Minagawa; T Kita; T Nishino; H Yaguchi; Y Shiraki
JOURNAL OF APPLIED PHYSICS, 巻：80, 号：8, 開始ページ：4592, 終了ページ：4598, 1996年10月, ［査読有り］
The optical processes in AlInP/GaInP/AlInP quantum wells free from long-range ordering are examined by photoluminescence (PL), photoluminescence excitation (PLE), acid photoreflectance (PR) measurements. The PL method observes lower transition energy than the PLE and the PR methods which observe the space-averaged transition energy. This is because PL originates from localized lower-energy states to which an exciton state relaxes. By analyzing these measurements carried on 20- and 60-Angstrom-wide wells, the reason for this deviation is ascribed to the fluctuation of the transition energy due to the local variation of the well width by one molecular layer. The plausible share of the band offset for the conduction band against the energy gap difference at the Gamma point is obtained by comparing the experimentally obtained relative position of the energy levels in AlInP barriers and the 20 Angstrom GaInP well with the calculated ones. This is found to be 0.75 (+/-0.06). (C) 1996 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.363829
DOI ID：10.1063/1.363829, ISSN：0021-8979, ORCID：30384893, Web of Science ID：WOS:A1996VM27200055 - Anomalous optical absorption in ZnCdSe/ZnSe single quantum wells
Baoping Zhang; Takanari Yasui; Takashi Yasuda; Yusaburo Segawa; Hiroyuki Yaguchi; Yasuhiro Shiraki
Solid State Communications, 巻：99, 号：12, 開始ページ：897, 終了ページ：900, 1996年09月, ［査読有り］
The optical absorption in ZnCdSe/ZnSe single quantum wells was studied by analyzing their reflectance spectra measured by a Fourier transform spectrometer. At lower temperatures, we observed a decrease in the excitonic absorption. This is qualitatively explained using a polariton model with the absorption dominated by phonon scattering. We present a comparison with III-V materials. The result confirms the polariton model of light propagation in quantum wells. Copyright © 1996 Published by Elsevier Science Ltd.
PERGAMON-ELSEVIER SCIENCE LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0038-1098(96)00320-1
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DOI ID：10.1016/0038-1098(96)00320-1, ISSN：0038-1098, CiNii Articles ID：80009163673, ORCID：56291690, SCOPUS ID：0030244101, Web of Science ID：WOS:A1996VF72800007 - Rectangular AlGaAs/AlAs quantum wires using spontaneous vertical quantum wells
Pan WG; Yaguchi H; Onabe K; Ito R; Usami N; Shiraki Y
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：35, 号：2 SUPPL. B, 開始ページ：1214, 終了ページ：1216, 1996年02月, ［査読有り］
We propose a lateral confinement enhanced rectangular AlGaAs/AlAs quantum wire (QWR) structure grown in situ, which utilizes the Ga-rich AlGaAs spontaneous vertical quantum wells formed during the growth of the AlGaAs epilayer in the V-grooves. AlGaAs/AlAs QWR structures have been grown on V/grooved substrates by low-pressure metalorganic vapor phase epitaxy (MOVPE), and been investigated by transmission electron microscopy, photoluminescence and cathodoluminescence measurements.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.35.1214
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DOI ID：10.1143/JJAP.35.1214, ISSN：0021-4922, ORCID：30384891, SCOPUS ID：0030080393, Web of Science ID：WOS:A1996UD94100088 - Characterization of Si delta-doped GaAs using photoellipsometry and photoreflectance
M Mochizuki; K Kobayashi; H Yaguchi; T Saitoh; YM Xiong
INTERNATIONAL SYMPOSIUM ON POLARIZATION ANALYSIS AND APPLICATIONS TO DEVICE TECHNOLOGY, 巻：2873, 開始ページ：270, 終了ページ：273, 1996年
SPIE - INT SOC OPTICAL ENGINEERING, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.246238
DOI ID：10.1117/12.246238, ORCID：56291748, Web of Science ID：WOS:A1996BG27F00067 - Characterization of modulation-doped n-AlxGa1-xAs/GaAs heterostructure using spectroscopic ellipsometry and photoreflectance
CC Wong; M Mochizuki; H Yaguchi; T Saitoh; YM Xiong
INTERNATIONAL SYMPOSIUM ON POLARIZATION ANALYSIS AND APPLICATIONS TO DEVICE TECHNOLOGY, 巻：2873, 開始ページ：226, 終了ページ：229, 1996年
SPIE - INT SOC OPTICAL ENGINEERING, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.246226
DOI ID：10.1117/12.246226, Web of Science ID：WOS:A1996BG27F00056 - Growth temperature dependence of AlGaAs spontaneous vertical quantum wells on V-grooved substrates by low-pressure metalorganic vapor phase epitaxy
Wugen Pan; Hiroyuki Yaguchi; Kentaro Onabe; Yasuhiro Shiraki; Ryoichi Ito
Journal of Crystal Growth, 巻：158, 号：3, 開始ページ：205, 終了ページ：209, 1996年01月, ［査読有り］
We have studied the growth of AlGaAs on V-grooved GaAs substrates by low-pressure (100 Torr) metalorganic vapor phase epitaxy (MOVPE) in the temperature range of 600 to 700°C. The growth temperature dependence of facet formation, the facet dependence of AlGaAs composition on the V-grooves, and the growth temperature dependence of spontaneous vertical quantum well (SVQW) widths have been investigated by low temperature photoluminescence (PL), transmission electron micrograph (TEM) and spectrally and spatially resolved low temperature cathodoluminescence (CL). The width of the SVQW varies from 140 to 250 Å with increasing the growth temperature from 600 to 700°C.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0022-0248(95)00449-1
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DOI ID：10.1016/0022-0248(95)00449-1, ISSN：0022-0248, CiNii Articles ID：80008768230, ORCID：48141804, SCOPUS ID：0030561998, Web of Science ID：WOS:A1996TR88900003 - Built-in Electric Field Strength in InP/n+-InP Determined by Photoellipsometry and Photoreflectance
Yasuhiro SHIRAKI; Yi-Ming XIONG; HIROYUKI YAGUCHI
Extended Abstracts of the International Conference on Solid State Devices and Materials, 1996年
研究論文（学術雑誌）
DOI：https://doi.org/10.7567/SSDM.1996.PD-7-3
DOI ID：10.7567/SSDM.1996.PD-7-3, ORCID：56291753 - Time-resolved photoluminescence study on AlxGa1-xAs spontaneous vertical quantum well structures
Usami N; Pan WG; Yaguchi H; Ito R; Onabe K; Akiyama H; Shiraki Y
Applied Physics Letters, 巻：68, 号：23, 開始ページ：3221, 終了ページ：3223, 1996年, ［査読有り］
We report on time-resolved photoluminescence study of AlxGa1-xAs spontaneous vertical quantum well (SVQW) structures on GaAs V-grooved substrates. Four distinct photoluminescence peaks are observed originating from the spatial nonuniformity of the alloy compositions spontaneously formed during metalorganic vapor phase epitaxial growth. The decay time of the (111)A sidewall AlGaAs decreased with increasing temperature, while that of the SVQW increased. The rise time of the SVQW was found to be longer than the typical value of the exciton formation and increases with increasing temperature, indicating that the exciton formation is not limiting factor of the rise time. These results are explained in terms of the exciton diffusion toward the SVQW from the outer AlGaAs layers with less Ga compositions. In addition, two dimensionality of the SVQW was evidenced by temperature dependence of the radiative lifetime. © 1996 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.116443
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DOI ID：10.1063/1.116443, ISSN：0003-6951, ORCID：30384895, SCOPUS ID：0030567631, Web of Science ID：WOS:A1996UN63500004 - TENSILE-STRAINED GAASP/ALGAAS QUANTUM-WELLS GROWN BY LOW-PRESSURE METALORGANIC VAPOR-PHASE EPITAXY
WG PAN; H YAGUCHI; K ONABE; R ITO; Y SHIRAKI
JOURNAL OF APPLIED PHYSICS, 巻：78, 号：5, 開始ページ：3517, 終了ページ：3519, 1995年09月, ［査読有り］
Tensile-strained GaAs0.89P0.11/Al0.33Ga0.67As quantum wells have been grown by low-pressure metalorganic vapor phase epitaxy. The grown samples have been studied by low-temperature (6 K) and 100 K in-plane photoluminescence as well as cross-sectional polarized photoluminescence measurements. The experimental results show the coincident or reversal point of the light- and heavy-hole related transitions at the well width of 60 Angstrom, above which the low-temperature photoluminescence is given by the transition 1e-1lh. A theoretical calculation agrees well with the experimental results. (C) 1995 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.359987
DOI ID：10.1063/1.359987, ISSN：0021-8979, ORCID：30384899, Web of Science ID：WOS:A1995RR84500099 - The in Situ Growth of Lateral Confinement Enhanced Rectangular AlGaAs/AlAs Quantum Wires by Utilizing the Spontaneous Vertical Quantum Wells
PAN Wugen; YAGUCHI Hiroyuki; ONABE Kentaro; ITO Ryoichi; USAMI Noritaka; SHIRAKI Yasuhiro
Extended abstracts of the ... Conference on Solid State Devices and Materials, 巻：1995, 開始ページ：737, 終了ページ：739, 1995年08月
英語
CiNii Articles ID：10017203168, CiNii Books ID：AA10777858 - Optical property of GaAsP/AlGaAs strained-layer quantum well grown on GaAs-(111)B substrate
Zhang X; Karaki K; Yaguchi H; Onabe K; Ito R; Shraki Y
Applied Physics Letters, 巻：66, 号：2, 開始ページ：186, 終了ページ：188, 1995年, ［査読有り］
GaAs1-xPx/AlyGa1-yAs (x=0.07-0.15, y=0.3) strained-layer quantum wells have been grown on GaAs-(111)B substrates by low-pressure metalorganic vapor phase epitaxy and characterized by photoluminescence (PL) spectroscopy. Evident energy blue shifts of the excitonic transition peaks (some of them as large as 33 meV) were achieved by increasing the excitation power during the PL measurement. The large optical nonlinearity mainly due to the strain-induced piezoelectric field screened by the photoexcited carriers, is comparable to, or larger than, the reported values for a self-electro-optical effect device or other (111)-oriented strained-layer quantum well structures which are composed of InGaAs/GaAs or GaAs/GaAsP. This fact indicates that our (111)-GaAsP/AlGaAs strained-layer quantum well is a good candidate for making optoelectronic devices like optical switches and modulators. © 1995 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.113129
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DOI ID：10.1063/1.113129, ISSN：0003-6951, ORCID：30384898, SCOPUS ID：36449000705, Web of Science ID：WOS:A1995QA69800025 - GROWTH-PARAMETERS FOR METASTABLE GAP1-XNX ALLOYS IN MOVPE
S MIYOSHI; H YAGUCHI; K ONABE; Y SHIRAKI; R ITO
COMPOUND SEMICONDUCTORS 1994, 巻：141, 号：141, 開始ページ：97, 終了ページ：100, 1995年, ［査読有り］
In order to clarify what determines the solid composition (x) in the metalorganic vapor phase epitaxy (MOVPE) of metastable GaP1-xNx alloys, we applied a growth interruption technique in this alloy growth. In our growth procedure, different from conventional MOVPE, the cycle of similar to 1 ML growth and growth interruption (only Ga precursor supply is turned off) is repeated. As increasing the growth interruption time, x decreases. This indicates that nitrogen atoms desorb from the film surface and that phosphorus atoms occupy the vacant sites during the growth interruption. The time constant of this substitution process is obtained to be 0.71, 0.47 and 0.39 sec at 655, 670 and 685 degrees C, respectively. This result can explain the growth temperature dependence and the growth rate dependence of x in the conventional MOVPE of this alloy system. It also gives a guide to growing the alloys with large x.
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
ISSN：0951-3248, ORCID：30384897, Web of Science ID：WOS:A1995BC92S00018 - Composition profile of an AlGaAs epilayer on a V-grooved substrate grown by low-pressure metalorganic vapor phase epitaxy
Pan WG; Yaguchi H; Onabe K; Ito R; Shiraki Y
Applied Physics Letters, 巻：67, 号：7, 開始ページ：959, 終了ページ：961, 1995年, ［査読有り］
A composition distribution of an AlxGa1-xAs epilayer on a V-grooved substrate grown by low-pressure metalorganic vapor phase epitaxy is described. The aluminum (Al) content of an AlxGa1-xAs epilayer on a V-grooved substrate is found to be on the order of x (111)A>xtop(100)>xedge-facet>x bottom-intersection by using spectrally and spatially resolved low temperature cathodoluminescence (CL) measurements. The composition difference between (111)A surfaces and bottom intersections is as much as 30%. The resulting spontaneous vertical quantum wells and spontaneous waveguides in the bottom intersections are expected to be applicable in low-threshold current laser devices.© 1995 American Institute of Physics.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.114708
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DOI ID：10.1063/1.114708, ISSN：0003-6951, ORCID：30384896, SCOPUS ID：21544436485, Web of Science ID：WOS:A1995RN57500028 - Effect of growth interruption on the interface flatness in metalorganic vapor phase epitaxy-grown GaAs/GaAsP heterostructures
Kazunobu Ota; Hiroyuki Yaguchi; Kentaro Onabe; Ryoichi Ito; Yasuhiro Shiraki
Journal of Crystal Growth, 巻：145, 号：1-4, 開始ページ：819, 終了ページ：823, 1994年12月, ［査読有り］
The interface flatness of metalorganic vapor phase epitaxy-grown GaAs/GaAsP strained barrier quantum wells has been studied with photoluminescence (PL). The PL peak clearly splits into two peaks when the growth rate is less than 1.7 Å/s or when the growth interruptions are introduced at the heterointerfaces. The energy separation between the two peaks corresponds to the well-width difference by a single monolayer. This indicates that the heterointerfaces are smoothed and that the islands of large lateral sizes are grown at the heterointerfaces. The growth interruption has been carried out either at the top (GaAsP on GaAs) or the bottom (GaAs on GaAsP) interface. It is found that the growth interruption is effective for smoothing both heterointerfaces. In addition, when the growth rate is 3.5 Å/s, the flatness of the growth front is retained during the growth of 90 Å layer. © 1994.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0022-0248(94)91148-7
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DOI ID：10.1016/0022-0248(94)91148-7, ISSN：0022-0248, CiNii Articles ID：80008075962, ORCID：56291705, SCOPUS ID：0028762033, Web of Science ID：WOS:A1994QC54300129 - Metalorganic vapor phase epitaxial growth and luminescence properties of GaAs/GaAsP quantum wires
Wugen Pan; Hiroyuki Yaguchi; Kentaro Onabe; Kazumi Wada; Yasuhiro Shiraki; Ryoichi Ito
Journal of Crystal Growth, 巻：145, 号：1-4, 開始ページ：702, 終了ページ：706, 1994年12月, ［査読有り］
Metalorganic vapor phase epitaxy (MOVPE) of GaAs/GaAsP quantum wires (QWRs) has been attempted on V-grooved GaAs (100) substrates. Intense photoluminescence (PL) from the wires as well as from the flat (100) quantum well layers (QWLs) has been obtained. The excitation-power dependence of the Pl spectra confirms the efficient capture and confinement of free carriers in the wire regions. The top views of cathodoluminescence (CL) images show that the QWR structures have been successfully grown. The polarization of PL shows a strong optical anistropy in QWRs due to two-dimensional quantum confinement. This is the first successful fabrication of GaAs/GaAsP QWR structures. © 1994.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0022-0248(94)91130-4
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DOI ID：10.1016/0022-0248(94)91130-4, ISSN：0022-0248, eISSN：1873-5002, CiNii Articles ID：80008075944, ORCID：56291683, SCOPUS ID：0028761934, Web of Science ID：WOS:A1994QC54300111 - Surface orientation dependence of growth rate of cubic GaN
Masaki Nagahara; Seiro Miyoshi; Hiroyuki Yaguchi; Kentaro Onabe; Yasuhiro Shiraki; Ryoichi Ito
Journal of Crystal Growth, 巻：145, 号：1-4, 開始ページ：197, 終了ページ：202, 1994年12月, ［査読有り］
The metalorganic vapor phase epitaxy (MOVPE) growth of cubic GaN has been performed on the patterned GaAs(100) substrates which have (111)A or (111)B facets. It is found that the growth features are strongly dependent on the configuration of the pattern. It is deduced that these features come from the surface-orientation-dependent growth rate, which is in the order (111)B > (100) > (111)A, combined with the diffusion of Ga adatoms on the surface. Taking advantage of the growth on the patterned substrates, the diffusion length of the Ga adatoms on the GaAs(100) surface is estimated to be several microns in the typical case. © 1994.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0022-0248(94)91050-2
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DOI ID：10.1016/0022-0248(94)91050-2, ISSN：0022-0248, CiNii Articles ID：80008075864, ORCID：56291698, SCOPUS ID：0028761939, Web of Science ID：WOS:A1994QC54300031 - INTERMEDIATE RANGE BETWEEN N-DOPED GAP AND GAP1-XNX ALLOYS - DIFFERENCE IN OPTICAL-PROPERTIES
S MIYOSHI; H YAGUCHI; K ONABE; R ITO; Y SHIRAKI
JOURNAL OF CRYSTAL GROWTH, 巻：145, 号：1-4, 開始ページ：87, 終了ページ：92, 1994年12月, ［査読有り］
Metalorganic vapor phase epitaxy (MOVPE) grown GaP1-xNx metastable alloys with relatively dilute nitrogen concentrations (0.03% less than or equal to 1.4%, i.e., 1 x 10(19) less than or equal to [N] less than or equal to 3 x 10(20) cm(-3)) have been studied with photoluminescence (PL). These nitrogen concentrations are especially interesting because they mediate between the N-doped GaP ([N] similar to 10(19) cm(-3)), where the PL spectrum is represented by the emissions due to excitons bound to nitrogen atom pairs (NNi, i = 1, 2, 3,...), and the alloy, where the PL should be associated with the band gap. The nitrogen concentration dependence of the PL spectra shows that the dominant emission changes from the shallow NNi centers (NN4, NN5) to the deepest one (NN1) with increasing x. The temperature dependence of the PL shows a similar systematic change in the spectrum. the integrated PL intensity versus x relationship indicates that at x > 0.4% (approximate to 1 x 10(20) cm(-3)) nitrogen-doped GaP may be properly looked upon as a GaP1-xNx alloy.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0022-0248(94)91033-2
DOI ID：10.1016/0022-0248(94)91033-2, ISSN：0022-0248, CiNii Articles ID：80008075847, ORCID：56291750, Web of Science ID：WOS:A1994QC54300014 - TEMPERATURE-DEPENDENCE OF PHOTOLUMINESCENCE LINEWIDTH IN GAAS/GAASP STRAINED-LAYER QUANTUM-WELL STRUCTURES
XN ZHANG; Y SHIRAKI; H YAGUCHI; K ONABE; R ITO
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, 巻：12, 号：4, 開始ページ：2293, 終了ページ：2298, 1994年07月, ［査読有り］
The temperature dependence of photoluminescence (PL) spectra for the GaAs/GaAsP strained-layer single quantum well structures has been investigated in detail. For temperatures below 77 K, the PL linewidth was found to first decrease and then to increase slowly as the temperature was enhanced. This phenomenon was clearly seen for the GaAs/Ga.AsP strained-barrier quantum wells exhibiting higher dislocation densities than the GaAs/GaAsP strained-well quantum wells. This fact strongly suggests that beside the unintentionally introduced impurities, the misfit dislocations may also play an important role in determining the temperature-dependent PL linewidth.
AMER INST PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1116/1.587755
DOI ID：10.1116/1.587755, ISSN：1071-1023, ORCID：30384911, Web of Science ID：WOS:A1994PD16100003 - Formation of Cubic GaN on (111)B GaAs by Metal-Organic Vapor-Phase Epitaxy with Dimethylhydrazine
Kuwano N; Kobayashi K; Oki K; Miyoshi S; Yaguchi H; Onabe K; Shiraki Y
Japanese Journal of Applied Physics, 巻：33, 号：6R, 開始ページ：3415, 終了ページ：3416, 1994年06月, ［査読有り］
The microstructure of GaN grown on (111)B GaAs by a metal-orgnic vapor-phase epitaxy method has been examined by transmission electron microscopy. Trimethylgallium and dimethylhydrazine were used as the source materials. It was revealed that the GaN crystal has a zincblende structure and is formed heterogeneously penetrating into the GaAs substrate. In a GaN crystal, stacking faults propagate on (111) planes other than those normal to the growth direction. © 1994 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.33.3415
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DOI ID：10.1143/JJAP.33.3415, ISSN：0021-4922, eISSN：1347-4065, ORCID：30384903, SCOPUS ID：0028442419, Web of Science ID：WOS:A1994PT64200021 - PHOTOREFLECTANCE STUDY OF INTERFACE ROUGHNESS IN GE/SIGE STRAINED-LAYER HETEROSTRUCTURES
H YAGUCHI; K TAI; K TAKEMASA; K ONABE; Y SHIRAKI; R ITO
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：33, 号：4B, 開始ページ：2353, 終了ページ：2356, 1994年04月, ［査読有り］
Ge/SiGe strained-layer heterostructures have been investigated using photoreflectance (PR) spectroscopy. On the basis of the comparison between the experimental and calculated quantum well-related transition energies formed at the GAMMA point, band discontinuities at the Ge/SiGe heterojunction are determined and found to vary linearly with Ge content in the SiGe layer. Conduction band offset ratio Q(c) (= DELTAE(c)/(DELTAE(c) + DELTAE(v)HH)) at the GAMMA point is evaluated to be 0.68 +/- 0.08. From the intrinsic linewidth of the quantum well-related transitions, roughness at the Ge/SiGe heterointerface has been characterized for the first time and is estimated to be +/-1 monolayer (ML). In addition, the splittings in the PR spectra are observed in some samples at low temperatures. These splittings are due to the difference in the well width and correspond to the height (or depth) of about 10 ML.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.33.2353
DOI ID：10.1143/JJAP.33.2353, ISSN：0021-4922, ORCID：30384908, Web of Science ID：WOS:A1994NR95900044 - Valence-subband level crossing in GaAs/GaAsP strained-barrier quantum well structures observed by circularly polarized photoluminescence excitation spectroscopy
Hiroyuki Yaguchi; Kazunobu Ota; Yutaka Takahashi; Koji Muraki; Kentaro Onabe; Yasuhiro Shiraki; Ryoichi Ito
Solid State Electronics, 巻：37, 号：4-6, 開始ページ：915, 終了ページ：918, 1994年, ［査読有り］
We have investigated the level configuration of the valence subbands in GaAs/GaAs1-xPx (x = 0.23) strained-barrier quantum well structures as a function of the well width. Circularly polarized photoluminescence excitation (CPPLE) spectroscopy was used to identify the heavy- or light-hole character of the optical transitions. Distinct polarization properties were observed in the strain-split heavy- and light-hole bands in the GaAsP barriers, which indicates the photoexcited electrons in the barriers retain spin orientation well even after the capture into the well and the relaxation process. Utilizing this polarization tendency of the transitions in the barriers, we could distinguish unequivocally the heavy- and light-hole character of the quantum well-related transitions. By varying the well width systematically, we observed the level crossing between n = 1 heavy- and light-hole transitions around the well width of 4 nm. This is in good agreement with the calculation based on the effective mass approximation. © 1994.
PERGAMON-ELSEVIER SCIENCE LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0038-1101(94)90325-5
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DOI ID：10.1016/0038-1101(94)90325-5, ISSN：0038-1101, CiNii Articles ID：80007544207, ORCID：56291777, SCOPUS ID：0028408432, Web of Science ID：WOS:A1994NE79600089 - Formation of facetted heterointerfaces of cubic GaN grown on GaAs(001) by metalorganic vapor phase epitaxy
N KUWANO; K KOBAYASHI; Y TAKEICHI; K OKI; S MIYOSHI; H YAGUCHI; K ONABE; Y SHIRAKI
ELECTRON MICROSCOPY 1994, VOLS 2A AND 2B, 開始ページ：619, 終了ページ：620, 1994年, ［査読有り］
EDITIONS PHYSIQUE, 英語, 研究論文（国際会議プロシーディングス）
ORCID：56291582, Web of Science ID：WOS:A1994BE09Y00300 - Transmission electron-microscope observation of cubic GaN grown by metalorganic vapor phase epitaxy with dimethylhydrazine on (001) GaAs
Kuwano N; Nagatomo Y; Kobayashi K; Oki K; Miyoshi S; Yaguchi H; Onabe K; Shiraki Y
Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, 巻：33, 号：1A, 開始ページ：18, 終了ページ：22, 1994年01月, ［査読有り］
Cross-sectional transmission electron microscope observation has been performed on the microstructure of GaN films grown on a (001) GaAs substrate by metalorgahic vapor phase epitaxy (MOVPE) using l,l-dimethylhydrazine (DMHy) and trimethylgallium (TMG) as the sources of nitrogen and gallium, respectively. Before the deposition, the surface of the substrate was nitrided with DMHy. High-resolution images and electron diffraction patterns confirmed that the GaN films have a zincblende structure (beta-GaN) with the lattice constant of a(GaN)=0.454 nm, and contain bands of stacking faults parallel to (111) planes. The interface between GaN and GaAs is made of (111) facets with no interlayer. Misfit dislocations are found to be inserted on the interface approximately every five atomic planes of GaAs. The nitridation treatment with only DMHy for 130 min is found to form a thick layer of beta-GaN on the (001) GaAs substrate. Nuclei of beta-GaN formed by the pretreatment of surface nitridation play an important role in growing GaN in a zincblende structure during the supply of DMHy and TMG. The formation of facets on the top surface of GaN and on the interface of GaN/GaAs is explained in terms of the diffusion of arsenic in beta-GaN. The characteristics of the structure of GaN films grown at 600 and 650 degrees C are also presented.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.33.18
DOI ID：10.1143/JJAP.33.18, ISSN：0021-4922, ORCID：30384912, Web of Science ID：WOS:A1994MV67700004 - SELECTIVE GROWTH OF CUBIC GAN IN SMALL AREAS ON PATTERNED GAAS(100) SUBSTRATES BY METALORGANIC VAPOR-PHASE EPITAXY
M NAGAHARA; S MIYOSHI; H YAGUCHI; K ONABE; Y SHIRAKI; R ITO
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：33, 号：1B, 開始ページ：694, 終了ページ：697, 1994年01月, ［査読有り］
The metalorganic vapor phase epitaxy growth of cubic GaN in small areas on SiO2-patterned GaAs substrates has been performed. We have succeeded in selective growth without deposition on the SiO2 mask at temperatures between 620 and 675 degrees C. The crystal quality of cubic GaN has been improved through growth in small areas on patterned GaAs substrates. It is found that the grain size becomes larger and the full width at half maximum of the X-ray diffraction peak of cubic GaN becomes narrower on patterned substrates than on unpatterned ones.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.33.694
DOI ID：10.1143/JJAP.33.694, ISSN：0021-4922, ORCID：30384909, Web of Science ID：WOS:A1994MV67800069 - Photoluminescence study of (111)-oriented GaAs/GaAsP strained-layer quantum well structure
Zhang X; Karaki K; Yaguchi H; Onabe K; Ito R; Shiraki Y
Applied Physics Letters, 巻：64, 号：12, 開始ページ：1555, 終了ページ：1557, 1994年, ［査読有り］
A GaAs/GaAs1-xPx (x=0.13) strained-layer quantum well structure has been grown on (111)B-oriented GaAs substrate by means of low-pressure (60 Torr) metalorganic vapor phase epitaxy and characterized by photoluminescence (PL) spectroscopy. Despite the partial relaxation of the tensile strain confined in the GaAsP barrier layers, our sample exhibits smooth surface morphology and intense optical emission. Moreover, an evident blue shift of the excitonic transition peak attributed to the screening of the strain-induced internal electric field by the photoexcited carriers, has been observed in the PL measurement.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.111991
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DOI ID：10.1063/1.111991, ISSN：0003-6951, ORCID：30384907, SCOPUS ID：0028385086, Web of Science ID：WOS:A1994NB63900032 - Characterization of Ge/SiGe Strained-Barrier Quantum-Well Structures Using Photoreflectance Spectroscopy
Yaguchi H; Tai K; Takemasa K; Onabe K; ITto R; Shiraki Y
Physical Review B, 巻：49, 号：11, 開始ページ：7394, 終了ページ：7399, 1994年, ［査読有り］
We have investigated Ge/SiGe strained-barrier quantum-well structures using photoreflectance spectroscopy. On the basis of the Γ-point transition energies associated with the Ge quantum well, the band offset at the heterojunction between Ge and SiGe has been found to vary linearly with the germanium composition in the SiGe barrier layer. The conduction-band-offset ratio Qc[=ΔEc/(ΔEc+ΔEvh)] at the Γ point is estimated to be 0.68±0.08. From the intrinsic linewidth of the quantum-well-related transitions, interface roughness has been characterized in this system and is estimated to be ±1 monolayer in our samples. © 1994 The American Physical Society.
研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevB.49.7394
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DOI ID：10.1103/PhysRevB.49.7394, ISSN：0163-1829, ORCID：30384900, SCOPUS ID：0039126902 - Self-modulating Sb incorporation in Si/SiGe superlattices during molecular beam epitaxial growth
K. Fujita; S. Fukatsu; N. Usami; Y. Shiraki; H. Yaguchi; R. Ito; K. Nakagawa
Surface Science, 巻：295, 号：3, 開始ページ：335, 終了ページ：339, 1993年10月, ［査読有り］
Self-modulating incorporation of Sb atoms has been found in Si/SiGe superlattices grown by conventional solid source Si molecular beam epitaxy. The origin of this phenomenon has been attributed to the difference in the segregation length of Sb atoms in Si and SiGe layers. It has been found that the segregation length of Sb in Si1-xGex layers increases as the Ge composition, x, increases and that Sb atoms are incorporated mainly in Si layers when Si/SiGe superlattices are grown. © 1993.
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0039-6028(93)90280-W
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0027681891&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0027681891&origin=inward
DOI ID：10.1016/0039-6028(93)90280-W, ISSN：0039-6028, CiNii Articles ID：80007270434, ORCID：56291770, SCOPUS ID：0027681891, Web of Science ID：WOS:A1993LZ22800011 - GAASP LAYERS GROWN ON (111)-ORIENTED GAAS SUBSTRATES BY METALORGANIC VAPOR-PHASE EPITAXY
ZHANG, X; K KARAKI; H YAGUCHI; K ONABE; Y SHIRAKI; R ITO
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 巻：32, 号：6A, 開始ページ：L755, 終了ページ：L757, 1993年06月, ［査読有り］
High-quality GaAsP layers have been grown on (111)B GaAs substrates for the first time by means of low-pressure (60 Torr) metalorganic vapor phase epitaxy (MOVPE) and characterized by double-crystal X-ray diffraction and photoluminescence (PL) spectroscopy. Despite the large lattice mismatch between the GaAsP epitaxial layers and GaAs substrates, the GaAsP layers grown at higher temperature and higher V/III gas flow ratio as compared to the corresponding growth on a (100)-oriented GaAs substrate, exhibit smooth surface morphology, unambiguous X-ray diffraction peak, and intense optical emission.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.32.L755
DOI ID：10.1143/JJAP.32.L755, ISSN：0021-4922, ORCID：30384914, Web of Science ID：WOS:A1993LF97200001 - Metal-organic vapor phase epitaxy growth and optical study of gaas/gaas
1-x px , strained-barrier single quantum well structures
Xiong Zhang; Kentaro Onabe; Hiroyuki Yaguchi; Yasuhiro Shiraki; Ryoichi Ito
Japanese Journal of Applied Physics, 巻：32, 号：3 B, 開始ページ：L375, 終了ページ：L378, 1993年03月
GaAs/GaAs1-xPx(x = 0.15, 0.20, 0.22) single quantum wells which involve tensile-strained GaAs/GaAs1-xPxbarrier layers have been grown on GaAs substrates by metal-organic vapor phase epitaxy (MOVPE) and characterized by double-crystal X-ray diffraction, photoluminescence (PL), and Fourier-transform reflectance spectroscopy (FT- RS). Despite the relatively large relaxation ratio of the strain (sometimes as high as 7.5%), these structures exhibit smooth surface morphology as well as intense and narrow excitonic emissions. The composition-dependent energy band offset ratios for the GaAs/GaAs1-xPxstrained-barrier single quantum well structures have also been determined. © 1993 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.32.L375
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DOI ID：10.1143/JJAP.32.L375, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：84939370422 - INTERSUBBAND ABSORPTION IN N-TYPE SI/SI1-XGEX MULTIPLE-QUANTUM-WELL STRUCTURES FORMED BY SB SEGREGANT-ASSISTED GROWTH
K FUJITA; S FUKATSU; Y SHIRAKI; H YAGUCHI; R ITO
JOURNAL OF CRYSTAL GROWTH, 巻：127, 号：1-4, 開始ページ：416, 終了ページ：420, 1993年02月
n-Si/Si1-xGex multiple quantum wells with ''abrupt'' heterointerfaces have been created by segregant-assisted growth (SAG) using Sb. Distinct well-width dependence of intersubband absorption energy in thinner quantum wells (L(z) = 14-26 angstrom) has been successfully observed. The well-width dependence of the absorption peak energy was in good agreement with a calculation based on the Kronig-Penney model where interfacial transience was taken to be shorter than than 0.4 nm. Present results show the potential power of SAG for creating ''abrupt'' Si/Si1-xGex interfaces.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0022-0248(93)90651-C
DOI ID：10.1016/0022-0248(93)90651-C, ISSN：0022-0248, Web of Science ID：WOS:A1993KZ45300088 - IS LOW-TEMPERATURE GROWTH THE SOLUTION TO ABRUPT SI/SI1-XGEX INTERFACE FORMATION
S FUKATSU; N USAMI; K FUJITA; H YAGUCHI; Y SHIRAKI; R ITO
JOURNAL OF CRYSTAL GROWTH, 巻：127, 号：1-4, 開始ページ：401, 終了ページ：405, 1993年02月
Si/Si1-xGex interface transients were investigated with respect to the abruptness and smoothness by using sputter depth profiling (SIMS), X-ray photoemissions (XPS), photoluminescence and transmission electron microscopy. Ge segregation was confirmed by blue-shift of luminescence energy above what is expected in a square well potential, along with SIMS measurement. Ge segregation was found to persist even at 300-degrees-C or lower. In contrast, Ge segregation was quenched by either segregant-assisted growth using Sb and Ga or solid-phase regrowth of Si cap layer; thereby a sharp Si/Si1-xGex interface was obtained. However, low-temperature-grown samples required an extensive anneal to restore band-edge luminescence, indicating a lack of quality of crystallinity.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0022-0248(93)90648-G
DOI ID：10.1016/0022-0248(93)90648-G, ISSN：0022-0248, Web of Science ID：WOS:A1993KZ45300085 - Highly conductive p-type cubic GaN epitaxial films on GaAs
S. Miyoshi; N. Ohkouchi; H. Yaguchi; K. Onabe; Y. Shiraki; R. Ito
Institute of Physics Conference Series, 巻：129, 開始ページ：79, 終了ページ：84, 1993年 - Characterization of Interface Roughness in Ge/SiGe Heterostructures Using Photoreflectance Spectroscopy
Yasuhiro SHIRAKI; Keizo TAKEMASA; Ryoichi ITO; Kentaro ONABE; Kaori TAI; HIROYUKI YAGUCHI
Extended Abstracts of the International Conference on Solid State Devices and Materials, 1993年
研究論文（学術雑誌）
DOI：https://doi.org/10.7567/SSDM.1993.S-I-6-6
DOI ID：10.7567/SSDM.1993.S-I-6-6, ORCID：56291716 - SELF-MODULATING INCORPORATION OF SB IN SI/SIGE, SUPERLATTICES DURING MOLECULAR-BEAM EPITAXIAL-GROWTH
K FUJITA; S FUKATSU; N USAMI; H YAGUCHI; Y SHIRAKI; R ITO
SHALLOW IMPURITIES IN SEMICONDUCTORS, 巻：117, 開始ページ：159, 終了ページ：164, 1993年, ［査読有り］
TRANS TECH PUBLICATIONS LTD, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.4028/www.scientific.net/MSF.117-118.159
DOI ID：10.4028/www.scientific.net/MSF.117-118.159, ISSN：0255-5476, ORCID：30384921, Web of Science ID：WOS:A1993BZ20P00024 - PHOTOREFLECTANCE STUDY OF GAAS/GAASP STRAINED-BARRIER QUANTUM-WELL STRUCTURES
H YAGUCHI; ZHANG, X; K OTA; M NAGAHARA; K ONABE; Y SHIRAKI; R ITO
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：32, 号：1B, 開始ページ：544, 終了ページ：547, 1993年01月, ［査読有り］
GaAs/GaAs1-xPx strained-barrier quantum well structures grown by metalorganic vapor phase epitaxy (MOVPE) have been investigated using photoreflectance (PR) spectroscopy. On the basis of the square-potential model, we have determined the band offsets at the heterojunction and their dependence on the phosphorus composition. It was found that in the GaAs/GaAs1-xPx strained-barrier quantum well, the band offsets are almost linearly dependent on the phosphorus composition in the range of x less-than-or-equal-to 0. 23. In addition, it was derived that the conduction band offset ratio Q(c) = 0.57+/-0.05. This result is consistent with our previous study concerning GaAs/GaAsP ''strained-well'' quantum well structures.
JAPAN J APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.32.544
DOI ID：10.1143/JJAP.32.544, ISSN：0021-4922, ORCID：30384920, Web of Science ID：WOS:A1993KQ00300059 - Observation of the valence-subband level crossing in GaAs/GaAsP strained-barrier quantum well structures using circularly polarized photoluminescence excitation spectroscopy
Ota K; Yaguchi H; Onabe K; Ito R; Takahashi Y; Muraki K; Shiraki Y
Applied Physics Letters, 巻：63, 号：7, 開始ページ：946, 終了ページ：948, 1993年, ［査読有り］
We have investigated the valence-subband level configuration in GaAs/GaAsP strained-barrier quantum wells as a function of the well width. As we systematically varied the well width, we observed the crossover behavior between the n=1 heavy- and light-hole states around the well width of 4 nm. Circularly polarized photoluminescence excitation (CPPLE) spectroscopy was used to identify the heavy- or light-hole character of the observed transitions. Distinct polarization properties were observed in the strain-split heavy- and light-hole states in the GaAsP barriers, which indicated that the photoexcited electrons in the barriers retained spin memory well even after the capture into the well through the relaxation process of energy and momentum. Taking advantage of this method we were able to identify unequivocally the heavy- and light-hole characters of the transitions in the quantum well. The well-width dependence of the intersubband transition energies obtained by the CPPLE measurement is in good agreement with the calculation based on the effective mass approximation.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.109853
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DOI ID：10.1063/1.109853, ISSN：0003-6951, ORCID：30384919, SCOPUS ID：36448998505 - Metalorganic vapor phase epitaxy of GaP1-xNx alloys on GaP
Miyoshi S; Yaguchi H; Onabe K; Ito R; Shiraki Y
Applied Physics Letters, 巻：63, 号：25, 開始ページ：3506, 終了ページ：3508, 1993年, ［査読有り］
We demonstrate a successful growth of GaP1-xNx alloys on GaP by metalorganic vapor phase epitaxy (MOVPE). This alloy system is predicted to have an extremely large miscibility gap, ranging from x=0.0000003 to 0.9999997 at 700°C. However, metastable alloys (x≤0.04) have been obtained at the growth temperature of 630-700°C. We focused on the growth condition dependence of solid composition (x). The nitrogen incorporation increases with decreasing growth temperature. It also increases with increasing growth rate, possibly due to nonequilibrium circumstances in the MOVPE growth. Low-temperature photoluminescence (PL) measurements show that the band gap of GaP1-xNx shifts to lower energy with increasing x.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.110109
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0346589553&origin=inward
DOI ID：10.1063/1.110109, ISSN：0003-6951, ORCID：30384918, SCOPUS ID：0346589553 - MOVPE GROWTH OF CUBIC GAN ON GAAS USING DIMETHYLHYDRAZINE
S MIYOSHI; K ONABE; N OHKOUCHI; H YAGUCHI; R ITO; S FUKATSU; Y SHIRAKI
JOURNAL OF CRYSTAL GROWTH, 巻：124, 号：1-4, 開始ページ：439, 終了ページ：442, 1992年11月
High-quality cubic GaN epitaxial films have been successfully grown on (100) GaAs substrates by metalorganic vapor phase epitaxy (MOVPE) using 1,1-dimethylhydrazine (DMHy) as the nitrogen source material. The full width at half maximum (FWHM) of the X-ray diffraction profile of 0.65-degrees has been obtained, which is the narrowest reported to date. The grown films were found to be made up of ridges with (111)B facets, with increasing film thickness. Raman peak characteristic of cubic symmetry has been obtained for the first time, showing that GaN films were of excellent quality.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0022-0248(92)90497-7
DOI ID：10.1016/0022-0248(92)90497-7, ISSN：0022-0248, Web of Science ID：WOS:A1992KB90500070 - Initial oxidation of MBE-grown Si( 100) surfaces
Yaguchi Hiroyuki; Fujita Ken; Fukatsu Susumu; Shiraki Yasuhiro; Ito Ryoichi; Igarashi Takayuki; Hattori Takeo
Surface Science, 巻：275, 号：3, 開始ページ：395, 終了ページ：400, 1992年09月
We have investigated the initial oxidation of MBE-grown Si(100) surfaces with atomic flatness using X-ray photoemission spectroscopy (XPS) and reflection high energy electron diffraction (RHEED). It was found that the MBE-grown surfaces are inert and hardly oxidized even after exposure to molecular oxygen up to 1500 L at room temperature and that the oxygen coverage is saturated at 0.4 ML. At elevated temperatures, however, the surface oxidation was substantially promoted on the atomically flat surface. On the other hand, the oxidation was found to proceed on a deliberately corrugated Si surface prepared by a low temperature MBE growth, even at room temperature. © 1992.
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0039-6028(92)90811-J
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DOI ID：10.1016/0039-6028(92)90811-J, ISSN：0039-6028, SCOPUS ID：0026918085 - ATOMISTIC PICTURE OF INTERFACIAL MIXING IN THE SI/GE HETEROSTRUCTURES
S FUKATSU; K FUJITA; H YAGUCHI; Y SHIRAKI; R ITO
SURFACE SCIENCE, 巻：267, 号：1-3, 開始ページ：79, 終了ページ：82, 1992年04月
Atomistic description of the interfacial mixing in the Si/Ge heterostructures during molecular beam epitaxial growth is presented. It is shown that the surface segregation of Ge atoms at the Si/Ge heterointerface is self-limited, i.e. controlled by Ge themselves, when their concentration is higher than 0.01 monolayer, due to the geometrical constraint arising from the surface bonding. In consequence, the Ge segregation exhibits a nonlinear behavior, which produces a non-exponential segregation profile. The Ge segregation is found to undergo a transition from a kinetically limited to an equilibrium regime around 400-degrees-C at a growth rate of 0.1 nm/s.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0039-6028(92)91093-Q
DOI ID：10.1016/0039-6028(92)91093-Q, ISSN：0039-6028, Web of Science ID：WOS:A1992HM90100022 - Photoreflectance Study of GaAs/GaAsP Strained-Barrier Quantum Well Structures
Hiroyuki YAGUCHI; Xiong ZHANG; Kentaro ONABE; Yasuhiro SHIRAKI; Ryoichi ITO
Extended Abstracts of the 1992 International Conference on Solid State Devices and Materials, 開始ページ：589, 終了ページ：591, 1992年, ［査読有り］
GaAsP strained-layer quantum well structures grown by metalorganic vapor phase epitaxy have been investigated using photoreflectance spectroscopy. We have focused our attention on GaAs/GaAsP 'strained-barrier' quantum well structures on GaAs(100) substrates. We have determined the band offset at the heterojunction and its dependence on the phosphorus composition. It was found that the band offsets are almost linearly dependent on the phosphorus composition in the range of x ≤ 0.23. In addition, it was derived that the conduction band offset ratio Qc = 0.57 ± 0.05.
The Japan Society of Applied Physics, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.7567/ssdm.1992.b-4-5
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DOI ID：10.7567/ssdm.1992.b-4-5, SCOPUS ID：0027002314 - Intersubband absorption in narrow Si/SiGe multiple quantum-wells without interfacial smearing
Fujita K; Fukatsu S; Shiraki Y; Yaguchi H; Ito R
Applied Physics Letters, 巻：61, 号：2, 開始ページ：210, 終了ページ：212, 1992年, ［査読有り］
Si/Si1-xGex multiple quantum wells with abrupt heterointerfaces have been formed by segregant-assisted growth (SAG) with Sb. Distinct well-width dependence of intersubband absorption in the narrow quantum wells has been observed. The well-width dependence of the absorption peak energy is in good agreement with a calculation based on the Kronig-Penney model where interfacial smearing is taken to be less than 0.4 nm, suggesting the integrity of Si/Si1-xGex interfaces grown by SAG.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.108220
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DOI ID：10.1063/1.108220, ISSN：0003-6951, ORCID：30384925, SCOPUS ID：0346609110 - Strain Relaxation in MBE-Grown Si1-xGex/Si(100) Heterostructures by Annealing
Yaguchi H; Fujita K; Futatsu S; Shiraki Y; Ito R
Japanese Journal of Applied Physics Part 2-Letters, 巻：30, 号：8 B, 開始ページ：L1450, 終了ページ：L1453, 1991年, ［査読有り］
Strain relaxation in MBE-grown Si1-xGex/Si(100) strained-layer heterostructures by postgrowth annealing has been investigated using X-ray diffraction and Nomarski microscopy. The extent of the strain relaxation is found to be dependent on Ge composition and annealing temperatures. The strain relaxation model proposed by Dodson and Tsao is applied to our experimental data and good agreement is obtained.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.30.L1450
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DOI ID：10.1143/JJAP.30.L1450, ISSN：0021-4922, ORCID：30384929, SCOPUS ID：0026207085 - Self-limitation in the surface segregation of Ge atoms during Si molecular beam epitaxial growth
Fukatsu S; Fujita K; Yaguchi H; Shiraki Y; Ito R
Applied Physics Letters, 巻：59, 号：17, 開始ページ：2103, 終了ページ：2105, 1991年, ［査読有り］
Self-limitation in the surface segregation of Ge atoms in the Si epitaxial overlayers arising from the surface bond geometry on Si(100) during molecular beam epitaxy has been investigated theoretically. It was found that Ge surface segregation is strongly limiting when the Ge concentration exceeds 0.01 monolayer. As a result of this self-limitation, segregation profiles of Ge in Si overlayers are found to decay nonexponentially in the growth direction with a kink in the profile around 3×1020 cm-3, which is in close agreement with the experimental observation. The kinetic barrier of the Ge surface segregation is estimated to be 1.63±0.1 eV.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.106412
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DOI ID：10.1063/1.106412, ISSN：0003-6951, ORCID：30384928, SCOPUS ID：36449004565 - Involvement of the topmost Ge layer in the Ge surface segregation during Si/Ge heterostructure formation
Fujita K; Fukatsu S; Yaguchi H; Shiraki Y; Ito R
Applied Physics Letters, 巻：59, 号：18, 開始ページ：2240, 終了ページ：2241, 1991年, ［査読有り］
Surface segregation of Ge atoms during Si/Ge heterostructure formation by molecular beam epitaxy has been investigated by x-ray photoemission spectroscopy varying the Ge layer thickness. It has been found that only the Ge atoms of the topmost layer are involved in the surface segregation, leaving the rest of the Ge atoms intact. This result supports the basic idea of the two-state-exchange model.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.106082
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DOI ID：10.1063/1.106082, ISSN：0003-6951, ORCID：30384927, SCOPUS ID：36449002825 - Realization of Abrupt interfaces in Si/Ge superlattices by suppressing Ge Surface Segregation with infmonolayer of Sb
Ken Fujita; Susumu Fukatsu; Hiroyuki Yaguchi; Takayuki Igarashi; Yasuhiro Shiraki; Ryoichi Ito
Japanese Journal of Applied Physics, 巻：29, 号：11, 開始ページ：L1981, 終了ページ：L1983, 1990年11月
Atomic mixing in Si/Ge strained-layer superlattices is investigated by means of SiMS and XPS. The interfacial mixing is attributed to the surface segregation of Ge atoms during MBE growth of Si overlayers. it is demonstrated that the surface segregation is remarkably suppressed by depositing infmonolayer Sb atoms on Ge layers prior to Si overgrowth and that Ge layers are confined to within 0.8 nm. © 1990 IOP Publishing Ltd.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.29.L1981
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DOI ID：10.1143/JJAP.29.L1981, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：3743115953 - Suppression of Interfacial Mixing in Si/Ge Superlattices by Sb Deposition
K. FUJITA; S. FUKATSU; H. YAGUCHI; T. IGARASHI; Y. SHIRAKI; R. ITO
Extended Abstracts of the 1990 International Conference on Solid State Devices and Materials, 開始ページ：1151, 終了ページ：1152, 1990年, ［査読有り］
Atomic mixing at Si/Ge interfaces in strained layer superlattices (SLS's) is investigated by means of SIMS and XPS. The interfacial mixing is attributed to surface segregation of Ge atoms on which Si layer is commensurately grown during MBE. It is demonstrated that the surface segregation is remarkably supressed by depositing submonolayer Sb atoms on Ge layers before Si overgrowth and that Ge layers are revealed to be confined to within 0.8nm.
The Japan Society of Applied Physics, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.7567/ssdm.1990.ln-d-1
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DOI ID：10.7567/ssdm.1990.ln-d-1, SCOPUS ID：0025554961 - RHEED Study of Superstructures of Submonolayer Lead Films on Silicon (111) Surfaces
Yaguchi H; Baba S; Kinbara A
Applied Surface Science, 巻：33-34, 号：C, 開始ページ：75, 終了ページ：80, 1988年09月, ［査読有り］
Coverage and temperature dependences of Pb/Si(111) surface structure have been investigated using reflection high energy electron diffraction (RHEED) and molecular beam deposition techniques. With the deposition of Pb on a clean Si(111) surface in the temperature range between 30 and 500 ° C, sequential changes in the RHEED pattern were observed in situ and thus a phase diagram of superstructures of submonolayer lead films on Si(111) surface could be established. © 1988.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0169-4332(88)90290-5
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DOI ID：10.1016/0169-4332(88)90290-5, ISSN：0169-4332, CiNii Articles ID：80004251511, ORCID：30384931, SCOPUS ID：0024067915, Web of Science ID：WOS:A1988Q431500011 - Pb/Si(111)表面超構造のRHEEDによる観察
H. Yaguchi; S. Baba; A. Kinbara
表面科学, 巻：9, 号：5, 開始ページ：368, 終了ページ：373, 1988年
研究論文（学術雑誌）
DOI：https://doi.org/10.1380/jsssj.9.368
DOI ID：10.1380/jsssj.9.368, ISSN：0388-5321, CiNii Articles ID：80004300663, ORCID：79735519 - ＲＨＥＥＤによるＰｂ／Ｓｉ（１１１）表面超構造の研究
矢口 裕之; 馬場 茂; 金原 粲
真空, 巻：31, 号：5, 開始ページ：399, 終了ページ：401, 1988年, ［査読有り］
一般社団法人 日本真空学会, 日本語, 研究論文（学術雑誌）
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DOI ID：10.3131/jvsj.31.399, ISSN：0559-8516, eISSN：1880-9413, CiNii Articles ID：130000863491, CiNii Books ID：AN00119871, ORCID：79735477, SCOPUS ID：85024451098
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J-Global ID：201702218011102092 - 1eV帯InGaAs:Nδドープ超格子の作製
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J-Global ID：201602220555984119 - Investigation of SiC/Oxide Interface Structures by Spectroscopic Ellipsometry
Sadafumi Yoshida; Yasuto Hijikata; Hiroyuki Yaguchi
2015年09月
DOI：https://doi.org/10.5772/61082
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J-Global ID：201502202887386651 - 微傾斜基板を用いたシングルドメイン立方晶GaNの成長と立方晶InNドット配列の形成
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J-Global ID：201502207598351728 - GaAs MBE成長におけるEr原子の表面偏析の温度依存性
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J-Global ID：201302203339195393 - 窒素δドープGaAs中の単一等電子トラップによる励起子分子発光の時間分解フォトルミネッセンス測定
高宮健吾; 八木修平; 土方泰斗; 望月敏光; 吉田正裕; 秋山英文; 窪谷茂幸; 片山竜二; 尾鍋研太郎; 矢口裕之
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J-Global ID：201302208930844769 - GaInNAs量子井戸の発光効率へのレーザー照射の影響
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J-Global ID：201302210710989914 - GaAsN/GaAs量子井戸構造からの発光の励起強度依存性
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J-Global ID：201302253457891105 - GaAs:Nδドープ超格子を用いた中間バンド型太陽電池の特性評価
八木修平; 野口駿介; 土方泰斗; 窪谷茂幸; 尾鍋研太郎; 岡田至崇; 矢口裕之
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日本語
J-Global ID：201302263267421817 - InN/GaNドット多重積層構造に向けたGaNキャップ層成長条件の検討
徳田英俊; 折原操; 八木修平; 土方泰斗; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：74th, 号：8, 開始ページ：ROMBUNNO.17P-P7-15, 終了ページ：08JL06-4, 2013年08月31日
Creation of short-period InN/GaN superlattices is one of the possible ways of conducting band gap engineering in the green-blue range of the spectrum. The present paper reports results of photoluminescence experiments, including pressure effects, on a superlattice sample consisting of unit cells with one monolayer of InN and 40 monolayers of GaN. The results are compared with calculations performed for different types of superlattices: InN/GaN, InGaN/GaN, and InN/InGaN/GaN with single monolayers of InN and/or InGaN. The superlattices are simulated by band structure calculations based on the local density approximation (LDA) with a semi-empirical correction for the ``LDA gap error''. A similarity is observed between the results of calculations for an InGaN/GaN superlattice (with one monolayer of InGaN) and the experimental results. This indicates that the fabricated InN quantum wells may contain some Ga atoms due to interdiffusion.
The Japan Society of Applied Physics, 日本語
DOI：https://doi.org/10.7567/JJAP.52.08JL06
DOI ID：10.7567/JJAP.52.08JL06, ISSN：0021-4922, J-Global ID：201302285385764625, CiNii Articles ID：40019758965, CiNii Books ID：AA12295836 - Ge/SiGe多重量子井戸への室温光スピン注入
安武裕輔; 矢口裕之; 深津晋
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：74th, 開始ページ：ROMBUNNO.16P-C15-3, 2013年08月31日
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J-Global ID：201302231556794835 - SiC酸化メカニズム解明への試み : Si酸化との共通点/異なる点 (シリコン材料・デバイス)
土方 泰斗; 八木 修平; 矢口 裕之
電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 巻：113, 号：87, 開始ページ：91, 終了ページ：96, 2013年06月18日
SiC半導体を用いたパワーMOSFETが従来のSi系パワーデバイスを凌駕するには,SiC酸化メカニズムのより一層の理解が不可欠である.本稿では,SiCの酸化メカニズムに対し,何がどこまでわかったかを総括し,Si酸化との共通点と相違点を織り交ぜながら近年の研究事例や課題を紹介していく.
一般社団法人電子情報通信学会, 日本語
ISSN：0913-5685, CiNii Articles ID：110009779110, CiNii Books ID：AN10013254 - RF‐MBE法による立方晶InNドット積層構造の作製
鈴木潤一郎; 折原操; 八木修平; 土方泰斗; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 巻：60th, 開始ページ：ROMBUNNO.28P-PA1-1, 2013年03月11日
日本語
J-Global ID：201302223183186110 - 4H‐SiCエピ膜中積層欠陥への熱酸化の影響について
宮野祐太郎; 八木修平; 土方泰斗; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 巻：60th, 開始ページ：ROMBUNNO.29P-PB4-9, 2013年03月11日
日本語
J-Global ID：201302267568241755 - 中間バンド型太陽電池へ向けたGaAs中窒素ドープ超格子のE+バンド光吸収の観測
野口駿介; 八木修平; 土方泰斗; 窪谷茂幸; 岡田至崇; 尾鍋研太郎; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 巻：60th, 開始ページ：ROMBUNNO.29A-PB7-19, 2013年03月11日
日本語
J-Global ID：201302299241158730 - Thermal Oxidation Mechanism of Silicon Carbide
Yasuto Hijikata; Shuhei Yagi; Hiroyuki Yaguchi; Sadafumi Yoshi
2012年10月
DOI：https://doi.org/10.5772/50748
DOI ID：10.5772/50748, ORCID put code：79780638 - Nondestructive and Contactless Characterization Method for Spatial Mapping of the Thickness and Electrical Properties in Homo-Epitaxially Grown SiC Epilayers Using Infrared Reflectance Spectroscopy
Sadafumi Yoshida; Yasuto Hijikata; Hiroyuki Yaguchi
2012年10月
DOI：https://doi.org/10.5772/50749
DOI ID：10.5772/50749, ORCID put code：79780627 - スパッタ薄膜成長による4H‐SiC基板中の非発光再結合中心生成
加藤寿悠; 八木修平; 土方泰斗; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：73rd, 開始ページ：ROMBUNNO.11P-PB2-12, 2012年08月27日
日本語
J-Global ID：201202222514720266 - 堆積と熱酸化による4H‐SiC MOS構造の作製
大谷篤志; 八木修平; 土方泰斗; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：73rd, 開始ページ：ROMBUNNO.11P-PB2-4, 2012年08月27日
日本語
J-Global ID：201202230425306688 - InN成長におけるInN高温バッファ層の効果に関する検討
増田篤; 折原操; 八木修平; 土方泰斗; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：73rd, 開始ページ：ROMBUNNO.12A-PB4-11, 2012年08月27日
日本語
J-Global ID：201202235572897960 - 第一原理計算によるGaAsNの電子構造に対する原子配置の影響に関する研究
坂本圭; 八木修平; 土方泰斗; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：73rd, 開始ページ：ROMBUNNO.12A-PB4-22, 2012年08月27日
日本語
J-Global ID：201202252900504833 - 窒素δドープGaAs中の単一等電子トラップからの発光のフォトルミネッセンス励起分光測定
高宮健吾; 八木修平; 土方泰斗; 望月敏光; 吉田正裕; 秋山英文; 窪谷茂幸; 尾鍋研太郎; 片山竜二; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：73rd, 開始ページ：ROMBUNNO.12P-PB11-20, 2012年08月27日
日本語
J-Global ID：201202257209482469 - MBE法によるGaAs(001)基板上へのErGaAs混晶の成長
JIN R; 八木修平; 土方泰斗; 窪谷茂幸; 尾鍋研太郎; 片山竜二; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：73rd, 開始ページ：ROMBUNNO.12P-PB11-16, 2012年08月27日
日本語
J-Global ID：201202271314197829 - RF‐MBE法によるGaAs(110)基板上への半極性InN成長に対する窒化の影響
五十嵐健; 折原操; 八木修平; 土方泰斗; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：73rd, 開始ページ：ROMBUNNO.12A-PB4-12, 2012年08月27日
日本語
J-Global ID：201202279081759741 - RF‐MBE法によるTiO2(001)基板上への立方晶GaNの成長
折原操; 八木修平; 土方泰斗; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：73rd, 開始ページ：ROMBUNNO.13P-H9-17, 2012年08月27日
日本語
J-Global ID：201202285680090400 - 熱酸化が4H‐SiCエピ膜中積層欠陥に及ぼす影響の顕微フォトルミネッセンスによる観察
山形光; 八木修平; 土方泰斗; 矢口裕之
応用物理学関係連合講演会講演予稿集(CD-ROM), 巻：59th, 開始ページ：ROMBUNNO.17P-A8-11, 2012年02月29日
日本語
J-Global ID：201202246861327481 - 窒素δドープGaAsにおける単一等電子トラップからの励起子分子発光
高宮健吾; 福島俊之; 星野真也; 八木修平; 土方泰斗; 望月敏光; 吉田正裕; 秋山英文; 窪谷茂幸; 尾鍋研太郎; 片山竜二; 矢口裕之
応用物理学関係連合講演会講演予稿集(CD-ROM), 巻：59th, 開始ページ：ROMBUNNO.17A-A8-9, 2012年02月29日
日本語
J-Global ID：201202254067781707 - 分光エリプソメトリによる立方晶InNの光学的特性評価
吉田倫大; 折原操; 八木修平; 土方泰斗; 矢口裕之
応用物理学関係連合講演会講演予稿集(CD-ROM), 巻：59th, 開始ページ：ROMBUNNO.16A-DP1-27, 2012年02月29日
日本語
J-Global ID：201202270422534312 - GaAs中窒素δドープ超格子のエネルギー構造評価
野口駿介; 八木修平; 土方泰斗; 窪谷茂幸; 尾鍋研太郎; 矢口裕之
応用物理学関係連合講演会講演予稿集(CD-ROM), 巻：59th, 開始ページ：ROMBUNNO.17P-DP3-12, 2012年02月29日
日本語
J-Global ID：201202272956548214 - 窒素δドープGaAs中の窒素原子対が形成する単一の等電子トラップからの発光に対する一軸応力の影響
新井佑也; 星野真也; 高宮健吾; 八木修平; 土方泰斗; 望月敏光; 吉田正裕; 秋山英文; 窪谷茂幸; 尾鍋研太郎; 矢口裕之
応用物理学関係連合講演会講演予稿集(CD-ROM), 巻：59th, 開始ページ：ROMBUNNO.17P-DP3-13, 2012年02月29日
日本語
J-Global ID：201202279946154581 - 共鳴トンネル構造を用いたエネルギー選択層における熱励起電流のホットキャリア型太陽電池特性への影響
八木修平; 土方泰斗; 岡田至崇; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：72nd, 開始ページ：ROMBUNNO.1A-H-12, 2011年08月16日
日本語
J-Global ID：201102252261232919 - Growth rate enhancement of silicon-carbide oxidation in thin oxide regime
Hijikata Yasuto; Yaguchi Hiroyuki; Yoshida Sadafumi; Gerhardt R
Properties and Applications of Silicon Carbide, 開始ページ：77, 終了ページ：87, 2011年, ［査読有り］
DOI：https://doi.org/10.5772/14591
DOI ID：10.5772/14591, ORCID put code：30384781, Web of Science ID：WOS:000363729000005 - 極低窒素濃度GaAsNのフォトリフレクタンススペクトル
大久保航; 石川輝; 八木修平; 土方泰斗; 吉田貞史; 片山竜二; 尾鍋研太郎; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：71st, 開始ページ：ROMBUNNO.14P-ZV-1, 2010年08月30日
日本語
J-Global ID：201002208945322457 - 極低窒素濃度GaAsN中の等電子トラップからの発光に対する一軸応力の影響
新井佑也; 遠藤雄太; 八木修平; 土方泰斗; 窪谷茂幸; 尾鍋研太郎; 片山竜二; 矢口裕之
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：71st, 開始ページ：ROMBUNNO.14P-ZV-2, 2010年08月30日
日本語
J-Global ID：201002211648568235 - 酸化中のSiC層へのSiおよびC原子放出についての理論的検討
土方泰斗; 八木修平; 矢口裕之; 吉田貞史
応用物理学会学術講演会講演予稿集(CD-ROM), 巻：71st, 開始ページ：ROMBUNNO.15A-ZS-10, 2010年08月30日
日本語
J-Global ID：201002219694574542 - 酸化中のSi及びC原子のSiC層への放出現象における理論的検討＜研究成果報告＞
土方 泰斗; 矢口 裕之; 吉田 貞史
埼玉大学工学部紀要 第一部 論文集, 巻：44, 開始ページ：34, 終了ページ：37, 2010年
To understand the structure of SiC-oxide interface more in detail, we propose a theory for calculating the depth profiles of Si and C emitted into SiC layer during oxidation. Simulations of the depth profiles of Si and C interstitials results in the structures analogous with those observed from a spectroscopic ellipsometry. To determine the diffusivities of Si and C interstitials, we performed capacitance-voltage measurements for examining the re-distribution profiles of nitrogen after oxidation. By comparing between observed and calculated profile, we obtained the self-diffusivity of C interstitials and confirmed that the proposed theory was appropriate to estimate depth profiles of Si and C interstitials emitted into SiC layer.
埼玉大学工学部広報委員会, 日本語
ISSN：1880-4446, CiNii Articles ID：120005386082 - 分光エリプソメトリによるSiC半導体の酸化界面評価と酸化メカニズム解明＜研究成果報告＞
土方 泰斗; 矢口 裕之; 吉田 貞史
埼玉大学工学部紀要 第一部 論文集, 巻：43, 開始ページ：17, 終了ページ：21, 2009年
We tried to elucidate the oxidizing interface structure of SiC semiconductor and its oxidation mechanism. First of all, we investigated the analysis method for deriving the thickness of interface layer and verified the validity of the method by analyzing the multi-angle measurement data. As a result of analysis for SiC-oxide interfaces using the analysis method, it is found that the photon energy dispersion of optical constants of the interface layer is similar to that for SiC, the real part of dielectric function is larger than that of SiC, and the imaginary part agrees with that of SiC. In addition, we examined the thickness dependence of optical constants of interface layer and found that the standing point in energy dispersion of the imaginary part of dielectric function shifted to the lower energy-side at 40 nm of oxide thickness. In addition to the observation of SiC-oxide interface, real-time measurements of oxide growth-rates of SiC at various oxidation temperatures were conducted using an in-situ spectroscopic ellipsometer. We tried to apply 'Si and C emission model', which is proposed as the SiC oxidation model by us, to the experimental growth-rate data. As a result, the Si and C emission model well reproduced the growth-rate at the entire oxide thickness region at all of the oxidation temperatures measured for both of (0001)Si-face and (000-1)C-face. Based on the knowledge on oxidizing interface layer and oxidation mechanism obtained from spectroscopic ellipsometry studies, we discuss the structure of interface layer and the formation mechanism of interface states.
埼玉大学工学部, 日本語
CiNii Articles ID：120005386070 - RF-MBE法を用いた3C-SiC基板上への立方晶InNの結晶成長およびその物性評価
富田康浩; 井上赳; 折原操; 土方泰斗; 矢口裕之; 吉田貞史; 平林康男
応用物理学関係連合講演会講演予稿集, 巻：55th, 号：1, 2008年
J-Global ID：200902203029436754 - 局所ドーピング半導体による単一光子発生に関する研究
矢口 裕之
旭硝子財団助成研究成果報告, 開始ページ：1, 終了ページ：7, 2008年
旭硝子財団, 日本語
ISSN：1882-0069, CiNii Articles ID：40019970578 - 閃亜鉛鉱構造窒化物半導体のエピタキシャル成長
矢口裕之
巻：34, 号：4, 開始ページ：201, 終了ページ：206, 2007年 - InN/InGaN系結晶の基礎物性解明および結晶成長のための基板探索--RF-MBE法によるサファイアR面基板上へのA面InNの結晶成長
吉田 貞史; 矢口 裕之; 折原 操
埼玉大学地域共同研究センター紀要, 号：8, 開始ページ：48, 終了ページ：51, 2007年
The improvement of the surface morphology of a-plane InN films grown by RF molecular beam epitaxy is reported. Using low-temperature (LT) InN buffer layers, we could successfully obtain InN films with a smooth surface. The full width at half maximum of the x-ray diffraction (11-20) rocking curve along the [0001] InN direction was 2200 arcsec for a-plane InN samples grown at 450°C with a LT-InN buffer layer. Thus, we could improve also the crystalline quality of a-plane InN films by using LT-InN buffer layers. We observed strong polarization anisotropy in the photoluminescence spectra of a-plane InN, which is typical of nonpolar wurtzite III-nitride films.
埼玉大学地域共同研究センター, 日本語
ISSN：1347-4758, CiNii Articles ID：40016200658, CiNii Books ID：AA11808968 - 極低窒素濃度化合物半導体混晶におけるアイソエレクトロニックトラップによる発光に関する研究<研究成果報告>
矢口 裕之; 青木 貴嗣
埼玉大学紀要. 工学部 第1編 第1部 論文集, 巻：39, 開始ページ：131, 終了ページ：132, 2006年07月
We have studied the photoluminescence from isoelectonic traps in dilute GaAsN alloys. A number of sharp luminescence peaks due to nitrogen pairs and their phonon replicas were observed. The energy differences between the luminescence peaks and phonon replicas were 36 meV, which is in agreement with the energy of the longitudinal optical phonon at the Γ point . This indicates that the formation of isoelectronic traps is largely affected by the conduction band state at the Γ point in dilute GaAsN alloys. We have also investigated the temperature dependence of the photoluminescence related to isoelectronic traps. The energy shift of the luminescence peaks with increasing temperature is found to be almost the same as that of E0 gap of GaAs, also showing that the conduction band state at the Γ point significantly contributes to the formation of isoelectronic traps in dilute GaAsN alloys.
埼玉大学工学部, 日本語
ISSN：1880-4446, CiNii Articles ID：120001370441 - 先端物質によるフロンティアフォトニクス<研究成果報告>
鎌田 憲彦; 明連 広昭; 矢口 裕之; 谷口 弘三
埼玉大学紀要. 工学部 第1編 第1部 論文集, 巻：39, 開始ページ：138, 終了ページ：142, 2006年07月
Based on science and technology of advanced materials, the quantum mechanical nature of photons can be utilized for expanding the available spectral window and strengthening the security of our social systems. Towards such frontier photonics, we started to study some basic elements from physical and technological aspects. We succeeded in growing β'-(BEDT-TTF)2ICl2 single crystals, detecting THz signal by our superconducting tunneling junction device. An in-situ ellipsometry enabled us to monitor thermal oxidation process of SiC surface, and a spectroscopic detection of non-radiative centers in a InAs/GaAs quantum dot structure became possible. The combination of quantum-mechanical design, nano-scale fabrication and detailed characterization is considered to be essential for proceeding the research frontier of brilliant photonics world.
埼玉大学工学部, 日本語
ISSN：1880-4446, CiNii Articles ID：120001370444 - InN/InGaN系結晶の基礎物性解明および結晶成長のための基板探索
吉田 貞史; 矢口 裕之; 折原 操
埼玉大学地域共同研究センター紀要, 巻：7, 開始ページ：63, 終了ページ：63, 2006年
埼玉大学総合研究機構地域共同研究センター産学連携推進部門, 日本語
ISSN：1347-4758, CiNii Articles ID：120001371315 - RF-MBE法を用いたMgO(001)基板上への立方晶InN薄膜の成長
吉田 貞史; 矢口 裕之; 折原 操
埼玉大学地域共同研究センター紀要, 巻：6, 開始ページ：71, 終了ページ：71, 2005年
埼玉大学総合研究機構地域共同研究センター産学連携推進部門, 日本語
ISSN：1347-4758, CiNii Articles ID：120001371341 - RFI-MBE法を用いたSiC基板上へのInNエピタキシャル層およびInN/InGaN量子井戸の成長
吉田 貞史; 矢口 裕之; 土方 泰斗; 折原 操
埼玉大学地域共同研究センター紀要, 巻：5, 開始ページ：63, 終了ページ：63, 2004年
埼玉大学地域共同研究センター, 日本語
ISSN：1347-4758, CiNii Articles ID：120001371469 - Photoemission spectroscopy and in-situ spectroscopic ellipsometry studies on the Ar post-oxidation-annealing effects of oxide/SiC interfaces
Y. Hijikata; S. Kawato; S. Sekiguchi; H. Yaguchi; Y. Ishida; M. Yoshiawa; T. Kamiya; S. Yoshida
開始ページ：127, 終了ページ：132, 2003年 - Spectroscopic ellipsometry study on the dielectric functions of GaPN alloys
H Kanaya; H Yaguchi; Y Hijikata; S Yoshida; S Miyoshi; K Onabe
巻：0, 号：7, 開始ページ：2753, 終了ページ：2756, 2003年
We have determined the complex dielectric functions of GaP1-xNx alloys using spectroscopic ellipsometry to clarify the electronic structure. With increasing N concentration, the E-1-gap peak height for both epsilon(1) and epsilon(2) decreases and the E-1-gap energy shifts to higher energies, showing that the electronic state at the L point is considerably changed due to the N incorporation. In the lower energy range, a broad peak appears near the fundamental band gap energy of GaP. With increasing N concentration, this peak becomes broader and the peak height increases. This indicates that the band-edge formation in GaP1-xNx alloys is extremely unique compared to that in conventional semiconductor alloys. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
英語
DOI：https://doi.org/10.1002/pssc.200303430
DOI ID：10.1002/pssc.200303430, ISSN：1862-6351, ORCID put code：56291710, Web of Science ID：WOS:000189401700183 - RF-MBE法を用いた六方晶および立方晶InNのエピタキシャル成長
吉田 貞史; 矢口 裕之; 土方 泰斗; 折原 操
埼玉大学地域共同研究センター紀要, 号：4, 開始ページ：61, 終了ページ：64, 2003年
We have grown InN films on 3C-SiC (001) substrates with and without cubic GaN underlayers by RF-MBE. It was found that, in the case of direct growth on 3C-SiC (001), hexagonal InN grows with the crystal orientation as hexagonal InN [1-100]//3C-SiC [110], while, in the case of the growth on cubic GaN underlayers, cubic InN grows with the crystal orientation as cubic InN [110]//cubic GaN [110]. Photoluminescence emissions from the cubic and hexagonal InN films were clearly observed at around 0.7 eV.
埼玉大学地域共同研究センター, 日本語
DOI：https://doi.org/10.24561/00016696
DOI ID：10.24561/00016696, ISSN：1347-4758, CiNii Articles ID：120006388491, CiNii Books ID：AA11808968 - 広禁制帯幅半導体のナノ表層構造評価用極端紫外分光装置の開発紫外分光偏光解析による広禁制帯幅半導体に関する研究開発
矢口 裕之; 土方 泰斗
埼玉大学地域共同研究センター紀要, 巻：3, 開始ページ：40, 終了ページ：40, 2002年
埼玉大学地域共同研究センター, 日本語
ISSN：1347-4758, CiNii Articles ID：120001371525 - 分光偏光解析等によるSiC酸化膜の評価
吉田 貞史; 矢口 裕之; 土方 泰斗; 折原 操
埼玉大学地域共同研究センター紀要, 号：3, 開始ページ：41, 終了ページ：48, 2002年
We have developed the method of obtaining the refractive indices of SiC/oxide interfaces by use of spectroscopic ellipsometry, and by using this method we have characterized SiC/oxide interfaces obtained by various oxidation methods and/or post oxidation annealing (POA). We have designed and fabricated the system with which in situ spectroscopic ellipsometry measurements can be carried out. We have observed the initial oxidation stage of SiC. We have also observed the changes of the refractive indices of interfaces by annealing in Ar atmosphere (Ar POA). The changes of atomic bond states at the interface by Ar POA were also observed by angle-resolved XPS and UPS, and compared with the results obtained form optical measurements and C-V measurements. We have developed the measurement method of obtaining carrier density and mobility distribution in SiC wafers by use of microscopic FT-IR. We have shown that the values obtained by this method well agree with those obtained from Hall measurements, suggesting that the method is useful to characterize electrical properties of SiC wafers quantitatively, non-destructively and without contact.
埼玉大学地域共同研究センター, 日本語
DOI：https://doi.org/10.24561/00016656
DOI ID：10.24561/00016656, ISSN：1347-4758, CiNii Articles ID：120006388453, CiNii Books ID：AA11808968 - 分光偏光解析等によるSiC酸化膜の評価
吉田 貞史; 矢口 裕之; 土方 泰斗
埼玉大学地域共同研究センター紀要, 号：2, 開始ページ：150, 終了ページ：156, 2001年
The characterization of oxidized films on SiC and oxide/SiC interfaces has been carried out by use of spectroscopic ellipsometry and XPS in order to make clear their dependences on the oxidation process. It was found that the refractive indices of the interfaces depend both on the oxide formation method and the method of post oxidation annealing. We found that the refractive indices for the oxide films deposited by low temperature CVD have lower interface refractive indices than those for dry oxidation and pyrogenic oxidation, and those for post oxidation annealed in· Ar atmosphere are lower that those for quenched samples. These results correspond well with the tendencies of interface state densities obtained by electrical measurements for the samples with the corresponding oxidation processes, except the cases of the oxidation processes containing hydrogen orland hydro-oxide base, like pyrogenic oxidation and wet re-oxidation. The XPS measurements have also shown the changes in the composition and bonding nature at the interfaces by the oxidation processes. We have shown the capability of microscopic FT -IR measurements for obtaining carrier density and mobility mapping of bulk SiC wafers.
埼玉大学地域共同研究センター, 日本語
ISSN：1347-4758, CiNii Articles ID：40006206458, CiNii Books ID：AA11808968 - 分光偏光解析等によるSiC酸化膜の評価
吉田 貞史; 矢口 裕之; 土方 泰斗
埼玉大学地域共同研究センター紀要, 号：1, 開始ページ：25, 終了ページ：32, 2000年
埼玉大学地域共同研究センター, 日本語
ISSN：1347-4758, CiNii Articles ID：40006206430, CiNii Books ID：AA11808968 - 炭化ケイ素高温半導体新結晶成長法の開発 : 結晶物性評価 <平成12年度 受託研究の概要>
吉田 貞史; 矢口 裕之; 土方 泰斗; 折原 操
埼玉大学地域共同研究センター紀要, 巻：1, 開始ページ：74, 終了ページ：74, 2000年
埼玉大学地域共同研究センター, 日本語
ISSN：1347-4758, CiNii Articles ID：120001389831 - Arsenic Surfactant and Incorporation Effects on Cubic GaN Grown by Metalorganic Vapor Phase Epitaxy
Tokuharu KIMURA; Seikoh YOSHIDA; Jun WU; Hiroyuki YAGUCHI; Kentaro ONABE; Yasuhiro SHIRAKI
1999年, ［査読有り］
英語
DOI：https://doi.org/10.7567/ssdm.1999.c-1-5
DOI ID：10.7567/ssdm.1999.c-1-5, ORCID put code：56291742 - 立方晶ナイトライドのMOVPE成長と評価
矢口 裕之; 呉 軍; 尾鍋 研太郎
電子情報通信学会技術研究報告. LQE, レーザ・量子エレクトロニクス, 巻：98, 号：109, 開始ページ：73, 終了ページ：78, 1998年06月16日
より結晶性の高い立方晶ナイトライドの成長を行うために有機金属気相成長における成長条件について検討を行った。その検討に基づいて成長した高品質な立方晶ナイトライドをフォトルミネッセンスによって評価し, いくつかの発光ピークについてその起源を明らかにした。さらに, 立方晶GaN/AlGaNダブルヘテロ構造を作製し, 光励起による誘導放出を観測した。
一般社団法人電子情報通信学会, 日本語
CiNii Articles ID：110003307581, CiNii Books ID：AN10442705 - Metalorganic vapor phase epitaxy of high quality cubic GaN, AlGaN and their application to optical devices
J Wu; H Yaguchi; K Onabe; Y Shiraki
開始ページ：715, 終了ページ：718, 1998年, ［査読有り］
We report on the growth of cubic GaN and AlGaN on GaAs (100) substrates by metalorganic vapor phase epitaxy (MOVPE). High optical quality cubic nitrides were obtained by optimizing the growth conditions. X-ray diffraction measurements confirmed the highly cubic nature of these films. Photoluminescence spectra showed dominant excitonic transition for both cubic GaN and AlGaN. Strong stimulated emission was observed from the cleaved edge of optically pumped cubic GaN/AlGaN double hetero (DH) structures.
英語
ORCID put code：56291604, Web of Science ID：WOS:000079631200176 - MOVPE growth of GaPAsN quaternary alloys lattice-matched to GaP
G Biwa; H Yaguchi; K Onabe; Y Shiraki
巻：482, 開始ページ：173, 終了ページ：178, 1998年, ［査読有り］
GaP1-x-yAsyNx (x similar to 2.3%, 0 < y < 19%) quaternary alloy semiconductor films on GaP substrates have been successfully grown by metalorganic vapor phase epitaxy (MOVPE). With the fixed supplies of trimethylgallium(TMG), AsH3 and dimethylhydrazine(DMHy) during the growth, the As concentration in the solid increased with increasing AsH3 supply, while the N concentration was almost unaffected. It has been demonstrated that the crystalline quality of the alloy films is much improved with the close lattice-matching to the GaP substrate, giving a superior surface morphology without any cross-hatches, a much narrower x-ray diffraction linewidth, and a significantly higher photoluminescence(PL) intensity.
英語
ISSN：0272-9172, Web of Science ID：WOS:000073983100026 - Metalorganic Vapor Phase Epitaxy of High Quality Cubic GaN,AlGaN and Their Application to Optical Devices
J. Wu; H. Yaguchi; K. Onabe; Y. Shiraki
開始ページ：715, 終了ページ：718, 1998年 - カソードルミネッセンスによる半導体低次元構造の評価
矢口裕之; 辻川智子; 尾鍋研太郎
巻：33, 開始ページ：217, 終了ページ：220, 1998年 - High Quality Cubic GaN Growth on GaAs (100) Substrates by Metalorganic Vapor Phase Epitaxy
WU Jun; YAGUCHI Hiroyuki; ONABE Kentaro; SHIRAKI Yasuhiro; ITO Ryoichi
Extended abstracts of the ... Conference on Solid State Devices and Materials, 巻：1997, 開始ページ：194, 終了ページ：195, 1997年09月16日
英語
CiNii Articles ID：10017194491, CiNii Books ID：AA10777858 - Polarization Characteristics of Crescent-Shaped Tensile-Strained GaAsP/AlGaAs Quantum Wire Lasers
ISHIKAWA Mitsuteru; PAN Wugen; KANEKO Yasuhisa; YAGUCHI Hiroyuki; ONABE Kentaro; ITO Ryoichi; SHIRAKI Yasuhiro
Extended abstracts of the ... Conference on Solid State Devices and Materials, 巻：1997, 開始ページ：342, 終了ページ：343, 1997年09月16日
英語
CiNii Articles ID：10017194971, CiNii Books ID：AA10777858 - GaAs/AlGaAs Quantum Structures Grown in Tetrahedral-Shaped Recesses on GaAs (111)B Substrates by MOVPE
TSUJIKAWA Tomoko; MOMMA Keishi; YAGUCHI Hiroyuki; ONABE Kentaro; SHIRAKI Yasuhiro; ITO Ryoichi
Extended abstracts of the ... Conference on Solid State Devices and Materials, 巻：1997, 開始ページ：318, 終了ページ：319, 1997年09月16日
英語
CiNii Articles ID：10017194909, CiNii Books ID：AA10777858 - GaPN混晶半導体のMOVPEと光学評価
矢口 裕之
電子情報通信学会技術研究報告. LQE, レーザ・量子エレクトロニクス, 巻：97, 号：100, 開始ページ：25, 終了ページ：30, 1997年06月17日
GaP_<1-x>N_x混晶のMOVPE成長における成長特性を検討することによって成長中の窒素の脱離が窒素組成に大きく影響することがわかった. また, 様々な光学評価によって, GaP_<1-x>N_x混晶における発光過程や緩和過程, 伝導帯の形成機構が明らかになった.
一般社団法人電子情報通信学会, 日本語
CiNii Articles ID：110003307129, CiNii Books ID：AN10442705 - Polarization properties of GaAsP/AlGaAs tensilely strained quantum wire structures grown on V-grooved GaAs substrates
W Pan; H Yaguchi; K Onabe; R Ito; N Usami; Y Shiraki
巻：145, 開始ページ：925, 終了ページ：930, 1996年, ［査読有り］
Crescent-shaped tensilely strained GaAs1-xPx/AlyGa1-yAs quantum wires (x = 0.11, y = 0.33) have been grown on 3-mu m-period V-grooved GaAs substrates by low-pressure metalorganic vapor phase epitaxy and characterized by cross-sectional transmission electron microscope observation, low temperature cross-sectional photoluminescence and cathodoluminescence. A drastic polarization transition from TM to TE with decreasing quantum wire size has been found in cross-sectional polarized photoluminescence.
英語
ISSN：0951-3248, ORCID put code：56291587, Web of Science ID：WOS:A1996BF51P00168 - Time-resolved photoluminescence study of radiative transition processes in GaP1-xNx alloys
H Yaguchi; S Miyoshi; H Arimoto; S Saito; H Akiyama; K Onabe; Y Shiraki; R Ito
巻：145, 開始ページ：307, 終了ページ：312, 1996年, ［査読有り］
Time-resolved photoluminescence (PL) measurements reveal that the radiative transition and carrier relaxation processes in GaP1-xNx alloys with high N concentrations are significantly different from those with low concentrations where NNi lines are clearly observed. The PL decay curve shows two distinct exponential processes for high concentrations while it is represented by a single exponential for low concentrations. The slow decay in GaP1-xNx alloys with high N concentrations indicates both the long radiative lifetime caused by the weak localization of excitons and the slow relaxation due to the scattered spatial distribution of the stales. This is consistent with the fact that the PL occurs at the tails of density of states, which is found from the comparison between absorption and PL spectra.
英語
ISSN：0951-3248, ORCID put code：56291776, Web of Science ID：WOS:A1996BF51P00055 - Strain effect on direct- and indirect-gap band lineups of GaAs1-xPx/GaP quantum wells
A Shima; H Yaguchi; K Onabe; Y Shiraki; R Ito
巻：145, 開始ページ：403, 終了ページ：408, 1996年, ［査読有り］
Strain effect on direct- and indirect-gap band lineups of strained GaAs1-xPx/GaP quantum wells with a wide range of x is studied using photoluminescence (PL) and photoreflectance (PR) spectroscopy. By comparing the transition energies obtained by PL and PR measurements with the calculation based on the effective mass approximation, it is found that the band lineups of strained GaAs1-xPx/GaP QWs on GaP substrates at any rr are of type I at the X and Gamma point and that the valence band offset of heavy hole is 506(1 - x) meV. As a result, it is deduced that biaxial compressive strain makes the energy gap of GaAs1-xPx alloys grown on GaP substrates indirect at any x.
英語
ISSN：0951-3248, ORCID put code：56291588, Web of Science ID：WOS:A1996BF51P00072 - Reflectance spectroscopy of ZnCdSe/ZnSe single quantum wells
B. P. Zhang; T. Yasui; T. Yasuda; Y. Segawa; H. Yaguchi; Y. Shiraki
RIKEN Review, 巻：11, 開始ページ：23, 終了ページ：24, 1995年 - MOVPE GROWTH OF STRAINED GAP1-XNX AND GAP1-XNX/GAP QUANTUM-WELLS
S MIYOSHI; H YAGUCHI; K ONABE; Y SHIRAKI; R ITO
巻：136, 号：136, 開始ページ：637, 終了ページ：642, 1994年, ［査読有り］
We report the successful growth of GaP1-xNx (x < 0.04) alloys on GaP by metalorganic vapor phase epitaxy (MOVPE). In spite of the large miscibility gap, which is calculated to el;tend from x = 0.00001 to 0.99999 at 700 degrees C, GaP1-xNx alloys have been obtained at the growth temperature of 630 similar to 700 degrees C. The peak energy of low-temperature photoluminescence (PL) spectra shows a redshift with increasing x. We have made strained GaP1-xNx (well) / GaP (barrier) multiple quantum wells (MQWs) and observed strong PL emission from these MQWs.
英語
ISSN：0951-3248, ORCID put code：56291580, Web of Science ID：WOS:A1994BB30L00105 - DETERMINATION OF BAND OFFSETS IN GAASP/GAP STRAINED-LAYER QUANTUM-WELL STRUCTURES USING PHOTOREFLECTANCE AND PHOTOLUMINESCENCE SPECTROSCOPY
Y HARA; H YAGUCHI; K ONABE; Y SHIRAKI; R ITO
巻：136, 号：136, 開始ページ：361, 終了ページ：366, 1994年, ［査読有り］
GaAs1-xPx(x=0.81,0.84,0.86) /GaP strained-layer quantum well (SLQW) structures have been studied using photoreflectance(PR) as well as photoluminescence(PL) spectroscopy. The PR measurements have revealed the optical transitions between the quantized subbands in the higher-lying quantum well at the Gamma point. From the PR measurements, combined with a square-potential effective-mass calculation, the conduction band offset ratio has been determined to be 0.68+/-0.1 for x=0.84. This result leads to the type-I quantum well at the X-point conduction band minima. The low-temperature PL spectra are very consistent with the type-I band scheme.
英語
ISSN：0951-3248, ORCID put code：56291623, Web of Science ID：WOS:A1994BB30L00060 - Initial Oxidation of MBE-Grown Si Surfaces
T. Igarashi; H. Yaguchi; K. Fujita; S. Fukatsu; Y. Shiraki; R. Ito; T. Hattori
巻：220, 開始ページ：35, 終了ページ：39, 1991年, ［査読有り］
We investigated the initial oxidation of MBE-grown Si (100) surfaces with atomic flatness using x-ray photoemission spectroscopy (XPS) and reflection high energy electron diffraction (RHEED). It was found that the MBE-grown surfaces are inert and hardly oxidized even after exposure to molecular oxygen up to 1500 Langmuir (L) at room temperature. At elevated temperatures, the surface oxidation was substantially promoted. On the contrary, the surface oxidation was found to be substantiated on a deliberately corrugated Si surface prepared by low temperature MBE growth, even at room temperature.
英語
DOI：https://doi.org/10.1557/proc-220-35
DOI ID：10.1557/proc-220-35, ISSN：0272-9172, eISSN：1946-4274, ORCID put code：56291586, Web of Science ID：WOS:A1991BU84B00005 - Suppression of Interfacial Mixing by Sb Deposition in Si/Ge Strained-Layer Superlattices
K. Fujita; S. Fukatsu; H. Yaguchi; T. Igarashi; Y. Shiraki; R. Ito
巻：220, 開始ページ：193, 終了ページ：197, 1991年, ［査読有り］
We have studied interfacial mixing of Si/Ge strained-layer superlattices during Si molecular beam epitaxy. The mixing has been shown to be primarily due to the surface segregation of Ge atoms during Si overlayer growth. It has been found that only the Ge atoms on the topmost Ge layer dominantly segregate to the growing surface. It has also been found that the surface segregation of Ge is effectively suppressed by depositing Sb atoms on the Ge layers. It has been demonstrated that Si/Ge superlattices with abrupt Si/Ge interfaces can be grown by depositing Sb. The two state exchange model is used to discuss the surface segregation of Ge and the suppression of the segregation by Sb deposition.
英語
DOI：https://doi.org/10.1557/proc-220-193
DOI ID：10.1557/proc-220-193, ISSN：0272-9172, eISSN：1946-4274, ORCID put code：56291656, Web of Science ID：WOS:A1991BU84B00029 - KINETICS OF GE SEGREGATION IN THE PRESENCE OF SB DURING MOLECULAR-BEAM EPITAXY
S FUKATSU; K FUJITA; H YAGUCHI; Y SHIRAKI; R ITO
巻：220, 開始ページ：217, 終了ページ：222, 1991年, ［査読有り］
英語
DOI：https://doi.org/10.1557/PROC-220-217
DOI ID：10.1557/PROC-220-217, ORCID put code：56291583, Web of Science ID：WOS:A1991BU84B00033 - Initial oxidation of MBE-grown Si surfaces
T. Igarashi; H. Yaguchi; K. Fujita; S. Fukatsu; Y. Shiraki; R. Ito; T. Hattori
巻：651, 開始ページ：35, 終了ページ：39, 1991年
We investigated the initial oxidation of MBE-grown Si (100) surfaces with atomic flatness using x-ray photoemission spectroscopy (XPS) and reflection high energy electron diffraction (RHEED). It was found that the MBE-grown surfaces are inert and hardly oxidized even after exposure to molecular oxygen up to 1500 Langmuir (L) at room temperature. At elevated temperatures, the surface oxidation was substantially promoted. On the contrary, the surface oxidation was found to be substantiated on a deliberately corrugated Si surface prepared by low temperature MBE growth, even at room temperature.
DOI：https://doi.org/10.1557/proc-220-35
DOI ID：10.1557/proc-220-35, ISSN：0272-9172, eISSN：1946-4274 - Suppression of interfacial mixing by Sb deposition in Si/Ge strained-layer superlattices
K. Fujita; S. Fukatsu; H. Yaguchi; T. Igarashi; Y. Shiraki; R. Ito
巻：651, 開始ページ：193, 終了ページ：197, 1991年
We have studied interfacial mixing of Si/Ge strained-layer superlattices during Si molecular beam epitaxy. The mixing has been shown to be primarily due to the surface segregation of Ge atoms during Si overlayer growth. It has been found that only the Ge atoms on the topmost Ge layer dominantly segregate to the growing surface. It has also been found that the surface segregation of Ge is effectively suppressed by depositing Sb atoms on the Ge layers. It has been demonstrated that Si/Ge superlattices with abrupt Si/Ge interfaces can be grown by depositing Sb. The two state exchange model is used to discuss the surface segregation of Ge and the suppression of the segregation by Sb deposition.
DOI：https://doi.org/10.1557/proc-220-193
DOI ID：10.1557/proc-220-193, ISSN：0272-9172, eISSN：1946-4274 - Kinetics of Ge segregation in the presence of Sb during molecular beam epitaxy
S. Fukatsu; K. Fujita; H. Yaguchi; Y. Shiraki; R. Ito
巻：651, 開始ページ：217, 終了ページ：222, 1991年 - 28p-K-10 ヘテロエピタキシャル薄膜中の転位の運動速度
山下 善文; 前田 康二; 目良 裕; 矢口 裕之; 白木 靖寛
年会講演予稿集, 巻：46, 号：0, 開始ページ：41, 終了ページ：41, 1991年
一般社団法人 日本物理学会, 日本語
DOI ID：10.11316/jpsgaiyod.46.2.0_41_2, CiNii Articles ID：110002149886, CiNii Books ID：AN10453938
- 薄膜作製応用ハンドブック
権田, 俊一; 酒井, 忠司; 田畑, 仁; 八瀬, 清志; 宮崎, 照宣, ［分担執筆］
エヌ・ティー・エス, 2020年02月
日本語, 総ページ数：38, 6, 16, 1468, 21, 15p
CiNii Books：http://ci.nii.ac.jp/ncid/BB29670662
ISBN：9784860436315, CiNii Books ID：BB29670662 - 初歩から学ぶ固体物理学
矢口, 裕之
講談社, 2017年
日本語, 総ページ数：vi, 312p
CiNii Books：http://ci.nii.ac.jp/ncid/BB23156746
ISBN：9784061532946, CiNii Books ID：BB23156746 - Advanced Silicon Carbide Devices and Processing
［分担執筆］
Intechopen, 2015年09月
総ページ数：258
ISBN：9535121685, ASIN：9535121685, EAN：9789535121688 - 薄膜の評価技術ハンドブック
吉田, 貞史; 金原, 粲, ［分担執筆］
テクノシステム, 2013年01月
日本語, 総ページ数：14, 624p
CiNii Books：http://ci.nii.ac.jp/ncid/BB11488829
ISBN：9784924728677, CiNii Books ID：BB11488829 - 理工学のための線形代数
長沢, 壮之; 江頭, 信二; 榎本, 裕子; 古城, 知己; 鈴木, 輝一(地盤工学); 矢口, 裕之; 柳瀬, 郁夫
培風館, 2013年
日本語, 総ページ数：iv, 193p
CiNii Books：http://ci.nii.ac.jp/ncid/BB12572749
ISBN：9784563004712, CiNii Books ID：BB12572749 - 薄膜ハンドブック
日本学術振興会薄膜第131委員会; 尾浦, 憲治郎; 吉田, 貞史, ［分担執筆］
オーム社, 2008年03月
日本語, 総ページ数：xvii, 1235p
CiNii Books：http://ci.nii.ac.jp/ncid/BA85340554
ISBN：9784274205194, CiNii Books ID：BA85340554 - 電気数学
吉田貞史; 菊池昭彦; 松田七美男; 矢口裕之; 明連広昭; 石谷善博; 金原粲
実教出版, 2008年
ISBN：9784407313178 - 等電子トラップを利用した単一光子発生素子の作製
矢口, 裕之
[矢口裕之], 2007年
総ページ数：50p
CiNii Books：http://ci.nii.ac.jp/ncid/BA82567702
CiNii Books ID：BA82567702 - 基礎物理２
金原粲; 吉田貞史; 江馬一弘; 馬場茂; 矢口裕之; 和田直久
実教出版, 2006年
ISBN：9784407308556 - Handbook of Semiconductor Nanostructures and Nanodevices(Optical Gain of Variously Strained Semiconductor Quantum Wells)
Y. Seko; H. Yaguchi, ［分担執筆］
American Scientific Publishers, Los Angeles, 2005年
ISBN：9781588830739 - III-Nitride Semiconductors: Optical Properties II (Chapter 9 Cubic Phase GaN and AlGaN: Epitaxial Growth and Optical Properties)
J. Wu; H. Yaguchi; K. Onabe, ［分担執筆］
Taylor & Francis Books, Inc., 2002年
ISBN：9781560329732
- First-principles study of the band tail states and optical properties of gallium phosphide nitride alloys
Hiroyuki Yaguchi
35th International Conference on the Physics of Semiconductors 2022, 2022年06月
英語, 口頭発表（一般）
共同研究・競争的資金等ID：24508454 - Arsenic Composition Dependence Of Up-conversion Luminescence Of Gallium Phosphide Arsenide Nitride Alloys
Kengo Takamiya; Sultan Md. Zamil; Shuhei Yagi; Hiroyuki Yaguchi
35th International Conference on the Physics of Semiconductors 2022, 2022年06月
英語, ポスター発表
共同研究・競争的資金等ID：24508454 - 分極効果p型層を用いた280 nm帯LDの試作と高電流注入発光の観測
仲元寺 郁弥; 前田 哲利; 糸数 雄吏; M. Ajmal Khan; 祝迫 恭; 矢口 裕之; 平山 秀樹
第69回応用物理学会春季学術講演会, 2022年03月
日本語, 口頭発表（一般） - AlGaN系深紫外LDのネットモード利得の波長依存性の解析
糸数 雄吏; 前田 哲利; 矢口 裕之; 平山 秀樹
第69回応用物理学会春季学術講演会, 2022年03月
日本語, 口頭発表（一般） - ErドープGaAsからの発光線の励起強度依存性
伊藤 駿平; 高宮 健吾; 小林 真隆; 八木 修平; 秋山 英文; 矢口 裕之
第69回応用物理学会春季学術講演会, 2022年03月
日本語, ポスター発表 - Optical Characterization of Carrier Recombination Process in GaPN Alloys: Excitation Source and Nitrogen Concentration Dependence
Hiroki Iwai; Sanjida Ferdous; Norihiko Kamata; Shuhei Yagi; Hiroyuki Yaguchi
2021 MRS Fall Meeting, 2021年12月
英語, 口頭発表（一般）
共同研究・競争的資金等ID：24508454 - 高パワー密度励起におけるGaAsのフォトルミネッセンス強度低下
高岡祥平; Md. Zamil Sultan; 高宮健吾; 八木修平; 矢口裕之
第82回応用物理学会秋季学術講演会, 2021年09月
日本語, ポスター発表 - InGaN-LED動作時の禁制帯内励起光照射による非発光再結合準位の検出
千代田夏樹; 鎌田憲彦; 矢口裕之
第68回応用物理学会春季学術講演会, 2021年03月
日本語, 口頭発表（一般） - 中間バンド型GaPN混晶のキャリア再結合過程の光学的評価：窒素濃度1.4%と3.2%の比較
岩井 広樹; フェルドス サンジーダ; 鎌田 憲彦; 八木 修平; 矢口 裕之
第68回応用物理学会春季学術講演会, 2021年03月
日本語, 口頭発表（一般）
共同研究・競争的資金等ID：24508454 - 第一原理計算を用いたGaPN混晶のバンドテイルによる光吸収についての検討
矢口裕之
第68回応用物理学会春季学術講演会, 2021年03月
日本語, ポスター発表
共同研究・競争的資金等ID：24508454 - GaPN混晶のアップコンバージョン発光へのバンドギャップエネルギーを超える励起光の影響
相良鋼; 高宮健吾; 八木修平; 矢口裕之
第81回応用物理学会秋季学術講演会, 2020年09月
日本語, 口頭発表（一般）
共同研究・競争的資金等ID：24508454 - 第一原理計算によるGaPN混晶におけるバンドテイル状態の検討
矢口裕之
第67回応用物理学会春季学術講演会, 2020年03月
日本語, ポスター発表
共同研究・競争的資金等ID：24508454 - Photoluminescence Intensity Change of InGaAsN Quantum Well by Laser Irradiation
Md Zamil Sultan; S. Yagi; K. Takamiya; H. Yaguchi
第67回応用物理学会春季学術講演会, 2020年03月
英語, 口頭発表（一般）
共同研究・競争的資金等ID：24508454 - Crystal Growth Control and Real-Time Analysis of Organolead-Halide Perovskite
Tetsuhiko Miyadera; Yuto Auchi; Kohei Yamamoto; Noboru Ohashi; Tomoyuki Koganezawa; Hiroyuki Yaguchi; Yuji Yoshida; Masayuki Chikamatsu
Asia-Pacific International Conference on Perpvskite, Organic Photovoltaices and Optoellectronics, 2020年01月
英語 - Crystal Growth Dynamics of CH3NH3PbI3 in Vacuum Deposition Process
T. Miyadera; Y. Auchi; K. Yamanoto; N. Ohashi; T. Koganezawa; H. Yaguchi; Y. Yoshida; M. Chikamatsu
Materials Research Meeting 2019, 2019年12月
英語 - DCスパッタAlNテンプレートを用いたUVC-LEDの進展
最上耀介; 大澤篤史; 尾崎一人; 谷岡千丈; 前岡淳史; 糸数雄吏; 桑葉俊輔; 定 昌史; 前田哲利; 矢口裕之; 平山秀樹
電子情報通信学会レーザ・量子エレクトロニクス研究会, 2019年11月
日本語, 口頭発表（一般） - Fabrication of UVC AlGaN LEDs on DC-sputtered AlN templates with hightemperature annealing
Y. Mogami; A. Osawa; K. Osaki; Y. Tanioka; A. Maeoka; Y. Itokazu; S. Kuwaba; M. Jo; N. Maeda; H. Yaguchi; H. Hirayama
The 9th Asia-Pacific Workshop on Widegap Semiconductors, 2019年11月
英語 - 真空プロセスによる鉛ハライドペロブスカイトの配向制御
宮寺哲彦; 阿内悠人; 山本晃平; 大橋昇; 小金澤智之; 矢口裕之; 吉田郵司; 近松真之
第68回高分子討論会, 2019年09月
日本語, 口頭発表（一般） - Growth of InN nanocolumns using a cubic GaN interlayer by RF-MBE
R. Onuma; S. Yagi; H. Yaguchi
7th International Workshop on Eptaxial Growth and Fundamental Properties of Semiconductor Nanostructures, 2019年09月
英語, ポスター発表 - Fabrication of Cubic InN Nanowires on GaN V-Groove Structures
Y. Nishimura; S. Yagi; H. Yaguchi
7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures, 2019年09月
英語, ポスター発表 - Upconversion Luminescence from GaPN Alloys with Various N Compositions
K. Takamiya; W. Takahashi; S. Yagi; N. Kamata; Y. Hazama; H. Akiyama; H. Yaguchi
7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures, 2019年09月
英語, ポスター発表
共同研究・競争的資金等ID：24508454 - Photoluminescence Intensity Change of GaPN by Laser Irradiation
Sultan Md. Zamil; A. Shiroma; S. Yagi; K. Takamiya; H. Yaguchi
7th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures, 2019年09月
英語, ポスター発表
共同研究・競争的資金等ID：24508454 - 窒素δ-ドープGaAs超格子の二波長励起フォトルミネッセンス法によるキャリア再結合準位評価
永田 航太; 鎌田 憲彦; 八木 修平; 矢口 裕之
第80回応用物理学会秋季学術講演会, 2019年09月
日本語, ポスター発表 - DCスパッタAlNを用いたAlGaN層格子緩和の促進
最上 耀介; 大澤 篤史; 尾崎 一人; 谷岡 千丈; 前岡 淳史; 糸数 雄吏; 桑葉 俊輔; 定 昌史; 前田 哲利; 矢口 裕之; 平山 秀樹
第80回応用物理学会秋季学術講演会, 2019年09月
日本語, 口頭発表（一般） - DCスパッタAlNテンプレート上UVC AlGaN LEDの作製と評価
最上 耀介; 大澤 篤史; 尾崎 一人; 谷岡 千丈; 前岡 淳史; 糸数 雄吏; 桑葉 俊輔; 定 昌史; 前田 哲利; 矢口 裕之; 平山 秀樹
第80回応用物理学会秋季学術講演会, 2019年09月
日本語, 口頭発表（一般） - GaN V溝構造を下地層とした立方晶InNナノワイヤの作製
西村 裕介; 八木 修平; 矢口 裕之
第80回応用物理学会秋季学術講演会, 2019年09月
日本語, ポスター発表 - RF-MBE法による立方晶GaN中間層を用いたInNナノコラムの成長
大沼 力也; 八木 修平; 矢口 裕之
第80回応用物理学会秋季学術講演会, 2019年09月
日本語, 口頭発表（一般） - (111)基板上に作製した窒素δドープGaAs中の単一等電子トラップによる励起子分子発光
高岡 祥平; 高宮 健吾; 八木 修平; 挟間 優治; 秋山 英文; 矢口 裕之
第80回応用物理学会秋季学術講演会, 2019年09月
日本語, 口頭発表（一般） - InGaAs:N δドープ超格子の電気特性評価
米野 龍司; 宮下 直也; 岡田 至崇; 八木 修平; 矢口 裕之
第80回応用物理学会秋季学術講演会, 2019年09月
英語, 口頭発表（一般） - Laser Induced Degradation of Photoluminescence Intensity in GaPN
Md Zamil Sultan; A. Shiroma; S. Yagi; K. Takamiya; H. Yaguchi
第80回応用物理学会秋季学術講演会, 2019年09月
英語, 口頭発表（一般）
共同研究・競争的資金等ID：24508454 - Two-Wavelength Excited Photoluminescence Study of Upconversion Photoluminescence from GaPN Alloys
H. Yaguchi; W. Takahashi; K. Takamiya; S. Yagi; N. Kamata; Y. Hazama; H. Akiyama
13th International Conference on Nitride Semiconductors, 2019年07月
英語, ポスター発表
共同研究・競争的資金等ID：24508454 - 有機鉛ペロブスカイト製膜過程リアルタイム観察
阿内悠人; 阿内悠人; 宮寺哲彦; 山本晃平; 小金澤智之; 近松真之; 吉田郵司; 矢口裕之
第66回応用物理学会春季学術講演会, 2019年03月
2019年 - 2019年, 日本語, 口頭発表（一般） - 規則配列化InNドットの作製に向けた立方晶GaN表面ステップ構造の成長条件依存性
大倉一将; 高宮健吾; 八木修平; 矢口裕之
第79回応用物理学会秋季講演, 2018年09月
2018年09月 - 2018年09月, 日本語 - 二波長励起PL測定によるGaPN混晶のアップコンバージョン発光特性評価
高橋渉; 高宮健吾; 八木修平; 狭間優治; 秋山英文; 矢口裕之; 鎌田憲彦
第79回応用物理学会秋季講演会, 2018年09月
2018年09月 - 2018年09月, 日本語, 口頭発表（一般） - 第一原理計算によるGaAsN混晶中のN原子配置のバンド構造への影響の検討
塚原悠太; 八木修平; 矢口裕之
第79回応用物理学会秋季講演会, 2018年09月
2018年09月 - 2018年09月, 日本語, 口頭発表（一般） - RF‐MBE成長による4H‐SiC(000-1)基板上へのN極性GaNの作製
杉浦亮; 高宮健吾; 八木修平; 矢口裕之
第79回応用物理学会秋季講演会, 2018年09月
2018年09月 - 2018年09月, 日本語 - MBE成長したErドープGaAsの発光特性に対するアニーリングの影響
五十嵐大輔; 高宮健吾; 伊藤隆; 八木修平; 秋山英文; 矢口裕之
第65回応用物理学会春季学術講演会, 2018年03月
2018年03月 - 2018年03月, 日本語 - 真空プロセスによる有機鉛ペロブスカイトの結晶成長制御
宮寺哲彦; 阿内悠人; 小金澤智之; 矢口裕之; 吉田郵司; 近松真之
第67回高分子討論会, 2018年09月
2018年 - 2018年 - First-principles study of optical transitions in dilute nitride semiconductor nanostructures
H. Yaguchi; S. Yagi; K. Takamiya
6th International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures, 2017年09月
英語, 口頭発表（招待・特別） - 希釈窒化物半導体中の窒素原子配置によるバンドギャップへの影響
宮島数喜; 八木修平; 庄司靖; 岡田至崇; 矢口裕之
第78回応用物理学会秋季学術講演会, 2017年09月
2017年08月 - 2017年08月, 日本語 - 新規可溶性オリゴチオフェン系電子ドナー材料を用いた有機薄膜太陽電池への溶媒蒸気アニーリング効果
秋山雄希; 秋山雄希; 橘浩昭; 阿澄玲子; 宮寺哲彦; 近松真之; 八木修平; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2017年08月
2017年08月 - 2017年08月, 日本語 - GaPN混晶のアップコンバージョン発光
高橋渉; 高宮健吾; 八木修平; 伊藤隆; 秋山英文; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2017年08月
2017年08月 - 2017年08月, 日本語 - DRCN5T/PCBMバルクヘテロ接合膜の溶媒蒸気アニーリング過程のその場観察
新井康司; 新井康司; 宮寺哲彦; 小金澤智之; 秋山雄希; 秋山雄希; 橘浩昭; 吉田郵司; 近松真之; 八木修平; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2017年03月
2017年03月 - 2017年03月, 日本語 - n型GaAs:Nδドープ超格子の電気的特性評価
加藤諒; 八木修平; 岡田至崇; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2017年03月
2017年03月 - 2017年03月, 日本語 - 1eV帯InGaAs:Nδドープ超格子の作製
梅田峻平; 八木修平; 宮下直也; 岡田至崇; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2017年03月
2017年03月 - 2017年03月, 日本語 - ErドープGaAsからの発光のMBE成長温度依存性
五十嵐大輔; 高宮健吾; 八木修平; 伊藤隆; 秋山英文; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2017年03月
2017年03月 - 2017年03月, 日本語 - ルブレン単結晶上の有機鉛ペロブスカイトのエピタキシャル成長
阿内悠人; 阿内悠人; 宮寺哲彦; 小金澤智之; 近松真之; 吉田郵司; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2017年
2017年 - 2017年 - 新規可溶性オリゴチオフェン系電子ドナー材料を用いた有機薄膜太陽電池
秋山雄希; 秋山雄希; 橘浩昭; 阿澄玲子; 宮寺哲彦; 近松真之; 小金澤智之; 矢口裕之; 八木修平
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2016年09月
2016年09月 - 2016年09月, 日本語 - レーザ照射によるGaInNAs混晶半導体の発光効率への影響
米倉成一; 高宮健吾; 八木修平; 上田修; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2016年09月
2016年09月 - 2016年09月, 日本語 - 4H‐SiC微傾斜基板上に作製した自己組織化InN/GaNドットの配列性制御
松岡圭佑; 八木修平; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2016年09月
2016年09月 - 2016年09月, 日本語 - 4H‐SiC基板の二波長励起PL測定―BGE強度依存性―
近藤圭太郎; 福田武司; 本多善太郎; 鎌田憲彦; 八木修平; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月
2016年03月 - 2016年03月, 日本語 - MgO微傾斜基板上に作製した立方晶InNドット配列構造の堆積量依存性
石井健一; 八木修平; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月
2016年03月 - 2016年03月, 日本語 - 添加剤導入によるP3HT薄膜の結晶成長過程のその場観察評価
新井康司; 新井康司; 宮寺哲彦; 小金澤智之; 秋山雄希; 秋山雄希; 杉田武; 近松真之; 八木修平; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2016年03月
2016年03月 - 2016年03月, 日本語 - 円偏光PLEによるGe直接遷移端への光スピン注入
安武裕輔; 安武裕輔; 太野垣健; 太野垣健; 大川洋平; 矢口裕之; 金光義彦; 深津晋
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2015年08月
2015年08月 - 2015年08月, 日本語 - ErドープGaAsからの発光に対する低温成長の影響
飯村啓泰; JIN R.G; 高宮健吾; 八木修平; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2015年08月
2015年08月 - 2015年08月, 日本語 - GaAs MBE成長におけるEr原子の表面偏析の温度依存性
JIN R; 高宮健吾; 八木修平; 土方泰斗; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2015年08月
2015年08月 - 2015年08月, 日本語 - 第一原理計算によるInAsN混晶の伝導帯の解析
宮崎貴史; 八木修平; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2015年08月
2015年08月 - 2015年08月, 日本語 - 微傾斜基板を用いたシングルドメイン立方晶GaNの成長と立方晶InNドット配列の形成
石井健一; 折原操; 八木修平; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2015年08月
2015年08月 - 2015年08月, 日本語 - 第一原理計算によるGaAs:Nδドープ超格子における光学遷移に関する研究
吉川洋生; 八木修平; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2015年08月
2015年08月 - 2015年08月, 日本語 - フォトルミネッセンス法による4H‐SiCエピ層中の酸化誘因欠陥の観察
浅藤亮祐; 八木修平; 土方泰斗; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2015年08月
2015年08月 - 2015年08月, 日本語 - AlAs/GaAs分布ブラッグ反射鏡を有するEr δドープGaAsの発光特性
須藤真樹; JIN R.G; 高宮健吾; 八木修平; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2015年08月
2015年08月 - 2015年08月, 日本語 - 第一原理計算によるInAsN混晶のバンド構造に関する研究
宮崎貴史; 八木修平; 土方泰斗; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2015年02月
2015年02月 - 2015年02月, 日本語 - 4H‐SiC(0001)微傾斜基板を用いたInNドット配列の自己形成
森誠也; 高宮健吾; 折原操; 八木修平; 土方泰斗; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2015年02月
2015年02月 - 2015年02月, 日本語 - GaAs:Nδドープ超格子を有する太陽電池の二段階光吸収
鈴木智也; 八木修平; 土方泰斗; 岡田至崇; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2015年02月
2015年02月 - 2015年02月, 日本語 - 添加剤導入によるP3HT:PCBM混合膜の結晶成長過程のその場観察評価
新井康司; 新井康司; 柴田陽生; 伊藤英輔; 小金澤智之; 宮寺哲彦; 宮寺哲彦; 近松真之; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2015年
2015年 - 2015年 - Geの磁場中時間分解円偏光フォトルミネッセンス
安武裕輔; 矢口裕之; 深津晋
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2014年09月
2014年09月 - 2014年09月, 日本語 - GaAs:Nδドープ超格子による中間バンド構造のエネルギー制御
長田一輝; 鈴木智也; 八木修平; 内藤駿弥; 庄司靖; 岡田至崇; 土方泰斗; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2014年09月
2014年09月 - 2014年09月, 日本語 - SiC酸化へのArアニール導入による酸化膜成長速度の変化
今野良太郎; 八木修平; 土方泰斗; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2014年09月
2014年09月 - 2014年09月, 日本語 - 中間バンド型太陽電池に向けたGaAs:Nδドープ超格子のMBE成長
鈴木智也; 長田一輝; 八木修平; 内藤駿弥; 土方泰斗; 岡田至崇; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2014年09月
2014年09月 - 2014年09月, 日本語 - RF‐MBE法によるGaAs(110)基板上へのGaNの成長
五十嵐健; 折原操; 八木修平; 土方泰斗; 窪谷茂幸; 片山竜二; 矢口裕之
応用物理学会春季学術講演会講演予稿集(CD-ROM), 2014年03月
2014年03月 - 2014年03月, 日本語 - 二波長励起PLによるGaPN混晶の光学特性評価
末次麻希子; TOUHIDUL ISLAM A.Z.M; 花岡司; 福田武司; 鎌田憲彦; 八木修平; 矢口裕之
照明学会全国大会講演論文集(CD-ROM), 2014年
2014年 - 2014年, 日本語 - 六方晶SiC無極性面の酸化過程の実時間観察
後藤大祐; 八木修平; 土方泰斗; 矢口裕之
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 2013年08月
2013年08月 - 2013年08月, 日本語 - Polarization properties of photoluminescence from individual isoelectronic traps in nitrogen delta-doped semiconductors: effect of host crystals
Hiroyuki Yaguchi
The Second International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures, 2009年08月
英語, 口頭発表（招待・特別） - SiおよびC原子放出モデルに基づく様々な酸化温度におけるSiC 酸化速度のモデル計算
SiC及び関連ワイドギャップ半導体研究会第18回講演会, 2009年 - 4H-SiC/酸化膜界面の光学的および電気的評価
SiC及び関連ワイドギャップ半導体研究会第18回講演会, 2009年 - In-situ分光エリプソメータによる低酸素分圧下におけるSiC酸化過程の観察
SiC及び関連ワイドギャップ半導体研究会第18回講演会, 2009年 - RF-MBE Growth of InN on 4H-SiC(0001) with Off-angles
8th International Conference on Nitride Semiconductors, 2009年 - Model calculation of SiC oxide growth rate at various oxidation temperatures based on the silicon and carbon emission model
International Conference on Silicon Carbide and Related Materials 2009, 2009年 - In-situ Spectroscopic Ellipsometry Study of SiC Oxidation at Low Oxygen-Partial-Pressures
International Conference on Silicon Carbide and Related Materials 2009, 2009年 - In-situ分光エリプソメ－タによる低酸素分圧下におけるSiC酸化過程の観察
第70回応用物理学会学術講演会, 2009年 - RF-MBE法による4H-SiC(0001)オフ基板上へのInN直接成長
第70回応用物理学会学術講演会, 2009年 - 窒素δドープGaAs/AlGaAsヘテロ構造における等電子トラップからの発光
第70回応用物理学会学術講演会, 2009年 - 極低窒素濃度GaAsNのフォトルミネッセンス励起分光測定
第70回応用物理学会学術講演会, 2009年 - フォトリフレクタンスによるGaAsNの電子構造に関する研究
第70回応用物理学会学術講演会, 2009年 - GaAs(001)および(111)面基板上に作製した窒素δドープGaAs中の等電子トラップからの発光
第５回量子ナノ材料セミナー, 2009年 - Photoluminescence from single isoelectronic traps in nitrogen delta-doped GaAs grown on GaAs(111)A
The 14th International Conference on Modulated Semiconductor Structures, 2009年 - SiおよびC原子放出モデルに基づく様々な酸化温度におけるSiC 酸化速度のモデル計算
SiC及び関連ワイドギャップ半導体研究会第18回講演会, 2009年 - 4H-SiC/酸化膜界面の光学的および電気的評価
SiC及び関連ワイドギャップ半導体研究会第18回講演会, 2009年 - In-situ分光エリプソメータによる低酸素分圧下におけるSiC酸化過程の観察
SiC及び関連ワイドギャップ半導体研究会第18回講演会, 2009年 - RF-MBE Growth of InN on 4H-SiC(0001) with Off-angles
8th International Conference on Nitride Semiconductors, 2009年 - Model calculation of SiC oxide growth rate at various oxidation temperatures based on the silicon and carbon emission model
International Conference on Silicon Carbide and Related Materials 2009, 2009年 - In-situ Spectroscopic Ellipsometry Study of SiC Oxidation at Low Oxygen-Partial-Pressures
International Conference on Silicon Carbide and Related Materials 2009, 2009年 - In-situ分光エリプソメ－タによる低酸素分圧下におけるSiC酸化過程の観察
第70回応用物理学会学術講演会, 2009年 - RF-MBE法による4H-SiC(0001)オフ基板上へのInN直接成長
第70回応用物理学会学術講演会, 2009年 - 窒素δドープGaAs/AlGaAsヘテロ構造における等電子トラップからの発光
第70回応用物理学会学術講演会, 2009年 - 極低窒素濃度GaAsNのフォトルミネッセンス励起分光測定
第70回応用物理学会学術講演会, 2009年 - フォトリフレクタンスによるGaAsNの電子構造に関する研究
第70回応用物理学会学術講演会, 2009年 - GaAs(001)および(111)面基板上に作製した窒素δドープGaAs中の等電子トラップからの発光
第５回量子ナノ材料セミナー, 2009年 - Photoluminescence from single isoelectronic traps in nitrogen delta-doped GaAs grown on GaAs(111)A
The 14th International Conference on Modulated Semiconductor Structures, 2009年 - 極低濃度窒素をドーピングしたGaAs中の等電子トラップからの発光
第55回応用物理学関係連合講演会講演予稿集, 2008年 - ラマン分光を用いたGaInAsN混晶の発光効率の変化に関する研究
第55回応用物理学関係連合講演会講演予稿集, 2008年 - 多入射角分光エリプソメトリによるSiC/酸化膜界面の光学的評価
第55回応用物理学関係連合講演会講演予稿集, 2008年 - In-situ分光エリプソメータによるSiCの極薄領域における酸化過程の観察
第55回応用物理学関係連合講演会講演予稿集, 2008年 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化膜厚依存性-
第55回応用物理学関係連合講演会講演予稿集, 2008年 - RF-MBE法を用いた3C-SiC基板上への立方晶InNの結晶成長およびその物性評価
第55回応用物理学関係連合講演会講演予稿集, 2008年 - RF-MBE法により成長させたA面InN膜のフォトルミネッセンス特性
第55回応用物理学関係連合講演会講演予稿集, 2008年 - RF-MBE法により成長した立方晶InNのPL測定 (II)
第55回応用物理学関係連合講演会講演予稿集, 2008年 - 極低濃度窒素をドーピングしたGaAs中の等電子トラップからの発光
第55回応用物理学関係連合講演会講演予稿集, 2008年 - ラマン分光を用いたGaInAsN混晶の発光効率の変化に関する研究
第55回応用物理学関係連合講演会講演予稿集, 2008年 - 多入射角分光エリプソメトリによるSiC/酸化膜界面の光学的評価
第55回応用物理学関係連合講演会講演予稿集, 2008年 - In-situ分光エリプソメータによるSiCの極薄領域における酸化過程の観察
第55回応用物理学関係連合講演会講演予稿集, 2008年 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化膜厚依存性-
第55回応用物理学関係連合講演会講演予稿集, 2008年 - RF-MBE法を用いた3C-SiC基板上への立方晶InNの結晶成長およびその物性評価
第55回応用物理学関係連合講演会講演予稿集, 2008年 - RF-MBE法により成長させたA面InN膜のフォトルミネッセンス特性
第55回応用物理学関係連合講演会講演予稿集, 2008年 - RF-MBE法により成長した立方晶InNのPL測定 (II)
第55回応用物理学関係連合講演会講演予稿集, 2008年 - SiC 酸化速度の極薄膜厚領域におけるモデル計算
2007年
ポスター発表 - n-situ 分光エリプソメータによるSiC 酸化速度の酸素分圧依存性測定
2007年
ポスター発表 - In-situ 分光エリプソメータによるSiC の極薄膜厚領域における酸化過程の観察
2007年
ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-(2)
2007年
ポスター発表 - Model Calculation of SiC Oxidation Rates in the Thin Oxide Regime
2007年
ポスター発表 - Oxygen-Partial-Pressure Dependence of SiC Oxidation Rate Studied by In-situ Spectroscopic Ellipsometry
2007年
ポスター発表 - Lattice Polarity Determination for GaN by Modulation Spectroscopy
Technical Program of the 7th International Conference on Nitride Semiconductors, 2007年 - Improvement of the Surface Morphology of a-Plane InN Using Low-Temperature InN Buffer Layers
Technical Program of the 7th International Conference on Nitride Semiconductors, 2007年 - Photoluminescence of Cubic InN Films on MgO(001) Substrates
Technical Program of the 7th International Conference on Nitride Semiconductors, 2007年
ポスター発表 - Photoluminescence Study of Hexagonal InN/InGaN Quantum Well Structures Grown on 3C-SiC (001) Substrates by Molecular Beam Epitax
Technical Program of the 7th International Conference on Nitride Semiconductors, 2007年
ポスター発表 - 変調分光法によるGaNの極性評価
第68回応用物理学会学術講演会講演予稿集, 2007年 - 光照射によるGaInAsN混晶の発光効率向上に関する研究
第68回応用物理学会学術講演会講演予稿集, 2007年 - 窒素をデルタドープしたGaAsにおける単一の等電子トラップからの発光の偏光特性
第68回応用物理学会学術講演会講演予稿集, 2007年 - 窒素をデルタドープしたGaP中の等電子トラップからの発光
第68回応用物理学会学術講演会講演予稿集, 2007年 - SiC酸化速度の極薄膜厚領域におけるモデル計算
第68回応用物理学会学術講演会講演予稿集, 2007年 - RF-MBE法を用いた4H-SiC基板(0001)面および(000-1)面上へのInGaN成長
第68回応用物理学会学術講演会講演予稿集, 2007年 - In-situ分光エリプソメ-タによるSiC酸化速度の酸素分圧依存性測定
第68回応用物理学会学術講演会講演予稿集, 2007年 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-
第68回応用物理学会学術講演会講演予稿集, 2007年 - 分光エリプソメトリによるInGaN混晶の光学的特性評価
第68回応用物理学会学術講演会講演予稿集, 2007年 - Twin photoluminescence peaks from single isoelectronic traps in nitrogen delta-doped GaAs
Abstract Book of the 13th International Conference on Modulated Semiconductor Structures, 2007年
ポスター発表 - Modulation spectroscopic investigation on lattice polarity of GaN
Extended Absctracts of the 26th Electronic Materials Symposium, 2007年 - RF-MBE法を用いた4H-SiC基板上へのInN/InGaN量子井戸構造の作製(III)
2007年 - RF-MBE法を用いた3C-SiC基板上へのInN/InGaN量子井戸構造の作製
2007年 - RF-MBE法によるGaNバッファー層を用いたサファイアR面基板上へのA面InNの成長
2007年 - 窒素をデルタドープしたGaAsにおける等電子トラップからの発光
2007年 - SiC 酸化速度の極薄膜厚領域におけるモデル計算
2007年
ポスター発表 - n-situ 分光エリプソメータによるSiC 酸化速度の酸素分圧依存性測定
2007年
ポスター発表 - In-situ 分光エリプソメータによるSiC の極薄膜厚領域における酸化過程の観察
2007年
ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-(2)
2007年
ポスター発表 - Model Calculation of SiC Oxidation Rates in the Thin Oxide Regime
2007年
ポスター発表 - Oxygen-Partial-Pressure Dependence of SiC Oxidation Rate Studied by In-situ Spectroscopic Ellipsometry
2007年
ポスター発表 - Lattice Polarity Determination for GaN by Modulation Spectroscopy
Technical Program of the 7th International Conference on Nitride Semiconductors, 2007年 - Improvement of the Surface Morphology of a-Plane InN Using Low-Temperature InN Buffer Layers
Technical Program of the 7th International Conference on Nitride Semiconductors, 2007年 - Photoluminescence of Cubic InN Films on MgO(001) Substrates
Technical Program of the 7th International Conference on Nitride Semiconductors, 2007年
ポスター発表 - Photoluminescence Study of Hexagonal InN/InGaN Quantum Well Structures Grown on 3C-SiC (001) Substrates by Molecular Beam Epitax
Technical Program of the 7th International Conference on Nitride Semiconductors, 2007年
ポスター発表 - 変調分光法によるGaNの極性評価
第68回応用物理学会学術講演会講演予稿集, 2007年 - 光照射によるGaInAsN混晶の発光効率向上に関する研究
第68回応用物理学会学術講演会講演予稿集, 2007年 - 窒素をデルタドープしたGaAsにおける単一の等電子トラップからの発光の偏光特性
第68回応用物理学会学術講演会講演予稿集, 2007年 - 窒素をデルタドープしたGaP中の等電子トラップからの発光
第68回応用物理学会学術講演会講演予稿集, 2007年 - SiC酸化速度の極薄膜厚領域におけるモデル計算
第68回応用物理学会学術講演会講演予稿集, 2007年 - RF-MBE法を用いた4H-SiC基板(0001)面および(000-1)面上へのInGaN成長
第68回応用物理学会学術講演会講演予稿集, 2007年 - In-situ分光エリプソメ-タによるSiC酸化速度の酸素分圧依存性測定
第68回応用物理学会学術講演会講演予稿集, 2007年 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-
第68回応用物理学会学術講演会講演予稿集, 2007年 - 分光エリプソメトリによるInGaN混晶の光学的特性評価
第68回応用物理学会学術講演会講演予稿集, 2007年 - Twin photoluminescence peaks from single isoelectronic traps in nitrogen delta-doped GaAs
Abstract Book of the 13th International Conference on Modulated Semiconductor Structures, 2007年
ポスター発表 - Modulation spectroscopic investigation on lattice polarity of GaN
Extended Absctracts of the 26th Electronic Materials Symposium, 2007年 - RF-MBE法を用いた4H-SiC基板上へのInN/InGaN量子井戸構造の作製(III)
2007年 - RF-MBE法を用いた3C-SiC基板上へのInN/InGaN量子井戸構造の作製
2007年 - RF-MBE法によるGaNバッファー層を用いたサファイアR面基板上へのA面InNの成長
2007年 - 窒素をデルタドープしたGaAsにおける等電子トラップからの発光
2007年 - 窒素イオン注入によりアモルファス化された4H-SiCを用いたMOSキャパシタの作製
2006年
ポスター発表 - テラヘルツ分光法によるSiC エピタキシャル成長膜のキャリヤ濃度、移動度、膜厚の同時評価
2006年
ポスター発表 - In-situ 分光エリプソメータによるSiC 酸化速度の酸素分圧依存性測定
2006年
ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -複数の入射角による測定-
2006年
ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-
2006年
ポスター発表 - GaN, InN結晶特性からみた立方晶、六方晶の違いに関する考察
2006年 - Structural and Optical Characterization of High In Content Cubic InGaN on GaAs(001) Substrates by RF-MBE
2006年
ポスター発表 - Photoluminescence Study of Isoelectronic Traps in Dilute GaAsN alloys
2006年
ポスター発表 - Micro-photoluminescence study on nitrogen atomic-layer doping in GaAs
2006年 - RF-MBE growth of InN/InGaN quantum well structures on 3C-SiC substrates
2006年
ポスター発表 - RF-MBE growth of a-plane InN on r-plane sapphire with a GaN underlayer
2006年
ポスター発表 - Simultaneous Determination of the Carrier Concentration, Mobility and Thickness of SiC Homo-Epilayers Using Terahertz Reflectance Spectroscopy
2006年
ポスター発表 - 窒素イオン注入によりアモルファス化された4H-SiCを用いたMOSキャパシタの作製
2006年 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-
2006年 - 赤外反射分光法を用いたSiCエピ膜の電気的特性の評価
2006年 - 分光エリプソメトリによる高In組成InGaN の光学的評価
2006年 - 窒素をδドープしたGaAs における等電子トラップの顕微フォトルミネッセンス測定
2006年 - RF-MBE法により成長した立方晶InNのPL測定
2006年 - Micro-photoluminescence study of nitrogen atomic-layer doped GaAs
2006年 - Micro-photoluminescence study of nitrogen delta-doped GaAs grown by metalorganic vapor phase epitaxy
2006年
ポスター発表 - Micro Raman study on the improvement of luminescence efficiency of GaAsN alloys
2006年
ポスター発表 - RF-MBE法を用いた立方晶InNの結晶成長(IV)
2006年 - ラマン分光を用いたGaAsN混晶の発光効率向上に関する研究
2006年 - In-situ分光エリプソメータによるSiCの酸化の実時間観察
2006年 - RF-MBE法を用いたSiC基板上へのInN/InGaN量子井戸構造の作製
2006年 - RF-MBE法を用いた3C-SiC(001)基板上への六方晶InNの結晶成長
2006年 - Real-time observation of SiC oxidation using an in situ spectroscopic ellipsometer
2006年 - 窒素イオン注入によりアモルファス化された4H-SiCを用いたMOSキャパシタの作製
2006年
ポスター発表 - テラヘルツ分光法によるSiC エピタキシャル成長膜のキャリヤ濃度、移動度、膜厚の同時評価
2006年
ポスター発表 - In-situ 分光エリプソメータによるSiC 酸化速度の酸素分圧依存性測定
2006年
ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -複数の入射角による測定-
2006年
ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-
2006年
ポスター発表 - GaN, InN結晶特性からみた立方晶、六方晶の違いに関する考察
2006年 - Structural and Optical Characterization of High In Content Cubic InGaN on GaAs(001) Substrates by RF-MBE
2006年
ポスター発表 - Photoluminescence Study of Isoelectronic Traps in Dilute GaAsN alloys
2006年
ポスター発表 - Micro-photoluminescence study on nitrogen atomic-layer doping in GaAs
2006年 - RF-MBE growth of InN/InGaN quantum well structures on 3C-SiC substrates
2006年
ポスター発表 - RF-MBE growth of a-plane InN on r-plane sapphire with a GaN underlayer
2006年
ポスター発表 - Simultaneous Determination of the Carrier Concentration, Mobility and Thickness of SiC Homo-Epilayers Using Terahertz Reflectance Spectroscopy
2006年
ポスター発表 - 窒素イオン注入によりアモルファス化された4H-SiCを用いたMOSキャパシタの作製
2006年 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-
2006年 - 赤外反射分光法を用いたSiCエピ膜の電気的特性の評価
2006年 - 分光エリプソメトリによる高In組成InGaN の光学的評価
2006年 - 窒素をδドープしたGaAs における等電子トラップの顕微フォトルミネッセンス測定
2006年 - RF-MBE法により成長した立方晶InNのPL測定
2006年 - Micro-photoluminescence study of nitrogen atomic-layer doped GaAs
2006年 - Micro-photoluminescence study of nitrogen delta-doped GaAs grown by metalorganic vapor phase epitaxy
2006年
ポスター発表 - Micro Raman study on the improvement of luminescence efficiency of GaAsN alloys
2006年
ポスター発表 - RF-MBE法を用いた立方晶InNの結晶成長(IV)
2006年 - ラマン分光を用いたGaAsN混晶の発光効率向上に関する研究
2006年 - In-situ分光エリプソメータによるSiCの酸化の実時間観察
2006年 - RF-MBE法を用いたSiC基板上へのInN/InGaN量子井戸構造の作製
2006年 - RF-MBE法を用いた3C-SiC(001)基板上への六方晶InNの結晶成長
2006年 - Real-time observation of SiC oxidation using an in situ spectroscopic ellipsometer
2006年 - RF-MBE法を用いた中間組成InGaN膜上へのInN/InGaN量子井戸構造の作製
平野 茂; 岩橋洋平; 折原 操; 土方泰斗; 矢口裕之; 吉田貞史
第66回応用物理学会学術講演会, 2005年09月
日本語, 口頭発表（一般） - RF-MBE法を用いた4H-SiC基板上へのInN/InGaN量子井戸構造の作製（II）
折原 操; 岩橋洋平; 平野 茂; 土方泰斗; 矢口裕之; 吉田貞史
第66回応用物理学会学術講演会, 2005年09月
日本語, 口頭発表（一般） - ラマン分光を用いたGaAsN混晶の光照射による構造変化の評価
矢口裕之; 清水博史; 森桶利和; 青木貴嗣; 土方泰斗; 吉田貞史; 宇佐美徳隆; 吉田正裕; 秋山英文; 青木大一郎; 尾鍋研太郎
第66回応用物理学会学術講演会, 2005年09月
日本語, 口頭発表（一般） - 低オフ角C面SiC基板上の酸化膜の評価
土方泰斗; 矢口裕之; 吉田貞史; 高田恭孝; 小林啓介; 野平博司; 服部健雄
第66回応用物理学会学術講演会, 2005年09月
日本語 - 赤外反射分光法を用いたSiCエピ膜の電気的特性の評価
大石慎吾; 土方泰斗; 矢口祐之; 吉田貞史
第66回応用物理学会学術講演会, 2005年09月
日本語, ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -紫外領域への拡張-
窪木亮一; 覚張光一; 土方泰斗; 矢口裕之; 吉田貞史
第66回応用物理学会学術講演会, 2005年09月
日本語, ポスター発表 - 様々な傾斜角を有するSiC基板上の酸化膜の評価
土方泰斗; 矢口裕之; 吉田貞史; 高田恭孝; 小林啓介; 野平博司; 服部健雄
第52回応用物理学関係連合講演会, 2005年04月
日本語, 口頭発表（一般） - In situ エリプソメータによるSiCの酸化の実時間観察
覚張光一; 窪木亮一; 土方泰斗; 矢口裕之; 吉田貞史
第52回応用物理学関係連合講演会, 2005年04月
日本語 - 赤外反射分光法を用いたSiCエピ膜の電気的特性の評価
大石慎吾; 土方泰斗; 矢口裕之; 吉田貞史
第52回応用物理学関係連合講演会, 2005年03月
日本語, 口頭発表（一般） - 窒素をδドープしたGaAsの顕微フォトルミネッセンス
花島君俊; 森桶利和; 青木貴嗣; 土方泰斗; 矢口裕之; 吉田貞史; 吉田正裕; 秋山英文; 平山琢; 片山竜二; 尾鍋研太郎
第52回応用物理学関係連合講演会, 2005年03月
日本語, ポスター発表 - RF-MBE法を用いた4H-SiC基板上へのInN/InGaN量子井戸構造の作製
折原操; 北村芳広; 岩橋洋平; 平野茂; 土方泰斗; 矢口裕之; 吉田貞史
第52回応用物理学関係連合講演会, 2005年03月
日本語, 口頭発表（一般） - Real Time Observation of SiC Oxidation Using In-Situ Spectroscopic Ellipsometer
Final Technical Program, 2005年
ポスター発表 - Off-Angle Dependence of Characteristics of 4H-SiC-Oxide Interfaces
Final Technical Progam, 2005年
ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -紫外領域への拡張-
2005年 - RF-MBE growth of cubic InN films on MgO (001) substrates
2005年
ポスター発表 - Photo-induced improvement of radiative efficiency and structural changes in GaAsN alloys
2005年
ポスター発表 - 分光エリプソメータによるSiO2/SiC界面の光学的評価 -紫外領域への拡張-
2005年
ポスター発表 - In-situ エリプソメータによるSiC の酸化の実時間観察
2005年
ポスター発表 - Real Time Observation of SiC Oxidation Using In-Situ Spectroscopic Ellipsometer
Final Technical Program, 2005年
ポスター発表 - Off-Angle Dependence of Characteristics of 4H-SiC-Oxide Interfaces
Final Technical Progam, 2005年
ポスター発表 - RF-MBE growth of cubic InN films on MgO (001) substrates
2005年
ポスター発表 - Photo-induced improvement of radiative efficiency and structural changes in GaAsN alloys
2005年
ポスター発表 - In-situ エリプソメータによるSiC の酸化の実時間観察
2005年
ポスター発表 - 分光エリプソメータによるSiC酸化膜の初期酸化過程の観察(IV)
覚張光一; 土方泰斗; 矢口裕之; 吉田貞史
第65回応用物理学会学術講演会, 2004年09月
日本語, 口頭発表（一般） - ラマン散乱分光法によるInAsN混晶の評価
本村寛; 土方泰斗; 矢口裕之; 吉田貞史; 飛田聡; 西尾晋; 片山竜二; 尾鍋研太郎
第65回応用物理学会学術講演会, 2004年09月
日本語, 口頭発表（一般） - 低窒素濃度GaPN混晶のフォトルミネッセンス
青木貴嗣; 森桶利和; 土方泰斗; 矢口裕之; 吉田貞史; 張保平; 三吉靖郎; 尾鍋研太郎
第65回応用物理学会学術講演会, 2004年09月
日本語, 口頭発表（一般） - レーザ照射によるGaAsN混晶の発光効率向上の窒素濃度依存性
森桶利和; 青木貴嗣; 呉智元; 吉田正裕; 秋山英文; 土方泰斗; 矢口裕之; 吉田貞史; 青木大一郎; 尾鍋研太郎
第65回応用物理学会学術講演会, 2004年09月
日本語, 口頭発表（一般） - RF-MBE法を用いた4H-SiC(0001)基板上へのInNの結晶成長
北村芳広; 岩橋洋平; 多田宏之; 折原操; 土方泰斗; 矢口裕之; 吉田貞史
第65回応用物理学科学術講演会, 2004年09月
日本語, 口頭発表（一般） - RF-MBE法によるMgO(001)基板上への立方晶GaNの成長
多田宏之; 北村芳広; 岩橋洋平; 折原操; 土方泰斗; 矢口裕之; 吉田貞史
第65回応用物理学会学術講演会, 2004年09月
日本語, 口頭発表（一般） - RF-MBE法を用いた4H-SiC基板上へのInGaN結晶成長
折原操; 北村芳広; 岩橋洋平; 多田宏之; 土方泰斗; 矢口裕之; 吉田貞史
第65回応用物理学会学術講演会, 2004年09月
日本語, 口頭発表（一般） - RF-MBE法を用いた立方晶InNの結晶成長(III)
岩橋洋平; 北村芳広; 多田宏之; 折原操; 土方泰斗; 矢口裕之; 吉田貞史
第65回応用物理学会学術講演会, 2004年09月
日本語, 口頭発表（一般） - Growth of high-quality hexagonal InN on 3C-SiC (001) by molecular beam epitaxy
H. Yaguchi; Y. Kitamura; K. Nishida; Y. Iwahashi; Y. Hijikata; S. Yoshida
International Workshop on Nitride Semiconductors Program & Abstract Book, 2004年07月
英語, 口頭発表（一般） - 高エネルギー分解能光電子分光による4H-SiC(000-1)面上酸化膜の評価
SiC及び関連ワイドギャップ半導体研究会第13回講演会予稿集, 2004年
ポスター発表 - 分光エリプソメータによるSiCの初期酸化過程の観察
SiC及び関連ワイドギャップ半導体研究会第13回講演会予稿集, 2004年
ポスター発表 - Epitaxial Growth of Hexagonal and Cubic InN Films by Gas Source Molecular Beam Epitaxy
Proceedings of 7th China-Japan Symposium on Thin Films, 2004年 - Characterization of Oxide Films on SiC Epitaxial (000-1) Faces by Angle-Resolved Photoemission Spectroscopic Measurements using Synchrotron Radiation
2004年
ポスター発表 - 高エネルギー分解能光電子分光による4H-SiC(000-1)面上酸化膜の評価
SiC及び関連ワイドギャップ半導体研究会第13回講演会予稿集, 2004年
ポスター発表 - 分光エリプソメータによるSiCの初期酸化過程の観察
SiC及び関連ワイドギャップ半導体研究会第13回講演会予稿集, 2004年
ポスター発表 - Epitaxial Growth of Hexagonal and Cubic InN Films by Gas Source Molecular Beam Epitaxy
Proceedings of 7th China-Japan Symposium on Thin Films, 2004年 - Characterization of Oxide Films on SiC Epitaxial (000-1) Faces by Angle-Resolved Photoemission Spectroscopic Measurements using Synchrotron Radiation
2004年
ポスター発表 - Characterization of oxide films on SiC by spectroscopic ellipsometer
Extended Abstracts of 1st International Workshop on Ultra-Low-Loss Power Device Technology, 2000年 - Characterization of oxide films on SiC by spectroscopic ellipsometer
Extended Abstracts of 1st International Workshop on Ultra-Low-Loss Power Device Technology, 2000年 - Built-in Electric Field Strength in InP/n+-InP Determined by Photoellipsometry and Photoreflectance
Extended Abstracts of the 1996 International Conference on Solid State Devices and Materials, 1996年 - The in Situ Growth of Lateral Confinement Enhanced Rectangular AlGaAs/AlAs Quantum Wires by Utilizing the Spontaneous Vertical Quantum Wells
Extended Abstracts of the 1995 International Conference on Solid State Devices and Materials, 1995年 - The in Situ Growth of Lateral Confinement Enhanced Rectangular AlGaAs/AlAs Quantum Wires by Utilizing the Spontaneous Vertical Quantum Wells
Extended Abstracts of the 1995 International Conference on Solid State Devices and Materials, 1995年 - Photoreflectance and Photoluminescence Study of Direct- and Indirect-Gap Band Lineups of GaAsP/GaP Strained Quantum Wells
Extended Abstracts of the 1994 International Conference on Solid State Devices and Materials, 1994年 - Photoreflectance and Photoluminescence Study of Direct- and Indirect-Gap Band Lineups of GaAsP/GaP Strained Quantum Wells
Extended Abstracts of the 1994 International Conference on Solid State Devices and Materials, 1994年 - Characterization of Interface Roughness in Ge/SiGe Heterostructures Using Photoreflectance Spectroscopy
Extended Abstracts of the 1993 International Conference on Solid State Devices and Materials, 1993年 - MOVPE Selective Growth of Cubic GaN in Small Areas on Patterned GaAs(100) Substrates
Extended Abstracts of the 1993 International Conference on Solid State Devices and Materials, 1993年 - Characterization of Interface Roughness in Ge/SiGe Heterostructures Using Photoreflectance Spectroscopy
Extended Abstracts of the 1993 International Conference on Solid State Devices and Materials, 1993年 - MOVPE Selective Growth of Cubic GaN in Small Areas on Patterned GaAs(100) Substrates
Extended Abstracts of the 1993 International Conference on Solid State Devices and Materials, 1993年 - Photoreflectance study of GaAs/GaAsP strained-barrier quantum well structures
Extended Abstracts of the 1992 International Conference on Solid State Devices and Materials, 1992年 - Photoreflectance study of GaAs/GaAsP strained-barrier quantum well structures
Extended Abstracts of the 1992 International Conference on Solid State Devices and Materials, 1992年 - 28p-K-10 ヘテロエピタキシャル薄膜中の転位の運動速度
山下 善文; 前田 康二; 目良 裕; 矢口 裕之; 白木 靖寛
年会講演予稿集, 1991年, 一般社団法人 日本物理学会
1991年 - 1991年, 日本語 - Si1-xGex歪薄膜の熱処理による歪の緩和
矢口裕之; 張保平; 藤田研; 深津晋; 白木靖寛; 伊藤良一
応用物理学会第51回講演会, 1990年09月
日本語, 口頭発表（一般） - SbによるSi/Ge界面ミキシングの抑制
藤田研; 深津晋; 矢口裕之; 五十嵐孝行; 張保平; 白木靖寛; 伊藤良一
応用物理学会第51回講演会, 1990年09月
日本語, 口頭発表（一般） - Suppression of Interfacial Mixing in Si/Ge Superlattices by Sb Deposition
K. Fujita; S. Fukatsu; H. Yaguchi; T. Igarashi; Y. Shiraki; R. Ito
22nd Conference on Solid State Devices and Materials, 1990年08月
英語, 口頭発表（一般） - 原子レベルで平坦なシリコン上の酸化膜形成とその構造
五十嵐孝行; 高瀬和彦; 服部健雄; 矢口裕之; 藤田研; 深津晋; 白木靖寛
第37回応用物理学関連連合講演会, 1990年03月
日本語, 口頭発表（一般） - Pb/Si(111)表面超構造のRHEEDによる観察
矢口裕之; 馬場茂; 金原粲
第7回表面科学講演大会, 1987年12月
日本語, 口頭発表（一般） - RHEEDによるPb/Si(111)表面超構造の研究
矢口裕之; 馬場茂; 金原粲
第28回真空に関する連合講演会, 1987年11月
日本語, 口頭発表（一般） - RHEED Study of Superstructures of Submonolayer Lead Films on Silicon(111) Surfaces
H. Yaguchi; S. Baba; A. Kinbara
4th International Conference on Solid Films and Surfaces, 1987年08月
英語, 口頭発表（一般）
■ 共同研究・競争的資金等の研究課題
- バンドテイルを経由した２段階光吸収を利用する太陽電池の高効率化
日本学術振興会, 科学研究費助成事業, 基盤研究(C), 2024年04月01日 - 2027年03月31日
矢口 裕之; 八木 修平; 高宮 健吾, 埼玉大学
配分額（総額）：4550000, 配分額（直接経費）：3500000, 配分額（間接経費）：1050000
課題番号：24K07574 - 希釈窒化物半導体における電子局在状態を活用する高効率太陽電池への展開
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 2019年04月01日 - 2022年03月31日
矢口 裕之; 秋山 英文; 高宮 健吾, 埼玉大学
配分額（総額）：17420000, 配分額（直接経費）：13400000, 配分額（間接経費）：4020000
希釈窒化物半導体における電子局在状態を介した２段階光吸収を活用するというアプローチで中間バンド型太陽電池の変換効率向上の可能性を検討した。スーパーセル法に基づく第一原理計算から、GaPN中の窒素原子配列がバンドギャップエネルギーを大きく変化させ、電子局在状態を形成する要因となることが明らかになった。二波長励起フォトルミネッセンス測定の励起強度依存性と試作した太陽電池の光電流特性から、バンドギャップよりも高エネルギーの光と低エネルギーの光とが太陽電池の効率向上につながるような光生成キャリアの増加を相乗的にもたらすことがわかった。
課題番号：19H02612
論文ID：39498365, 講演・口頭発表等ID：39504829, 受賞ID：33629959 - 紫外LED動作時の禁制帯内励起光照射による欠陥準位の検出・評価手法の確立
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 2018年04月01日 - 2021年03月31日
鎌田 憲彦; 矢口 裕之; 平山 秀樹, 埼玉大学
配分額（総額）：4160000, 配分額（直接経費）：3200000, 配分額（間接経費）：960000
市販されているSMD型紫外LEDを放熱プレート上に固定し、放熱プレートの温度をペルチエ素子で自動制御する試料マウント部を作製した。広帯域ロックインアンプSR865Aを導入し、EL、電流、電圧測定のための実験系を新たに整備した。室温付近の一定温度下でLEDを低電流駆動し、外部からBGE光を断続照射した際のBGE光ONおよびOFF時のEL強度IB、IEが異なることを確認した。両者の比IB/IEで規格化EL強度を定義し、この比が1からずれることによって欠陥準位を検出する。複数のUV-LEDを用いてこのEL強度変化（BGE効果）を観測し、LEDチップ形状での欠陥準位検出が可能であることを確認した。
駆動回路の直列抵抗値と駆動方法により規格化EL強度、電流増加量が異なることを再度確認した。回路要因を系統的に調べた結果、 EL強度変化（規格化EL強度IN：BGE光照射あり/なしでのEL強度の比）は定電流駆動条件を基準とする、定電圧条件ではBGE光照射による電流増加分がELに寄与するため、BGE効果は＋側にシフトする、電流値の増加量Δiは定電圧駆動条件で再現性良く測定可能である、定電流条件でBGE光を照射すると、一定電流を維持するために必要な電圧値が低下する、といった諸点が得られた。
駆動電流値を増すにつれ、BGE光照射による相対的なEL強度変化率（規格化EL強度）は低下するが、Δiは単調増加する。実際の定格電流駆動時での評価に近づくため、定電圧駆動時の電流増加量Δiに着目し、駆動電流400mAまでの領域でΔiの測定を達成した。ロックインアンプを導入して測定条件の改善を始め、成果の一部を発表した。
課題番号：18K04954 - 希釈窒化物半導体中の欠陥の挙動およびデバイスの信頼性向上に関する研究
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 2014年04月01日 - 2017年03月31日
上田 修; 池永 訓昭; 八木 修平; 矢口 裕之, 金沢工業大学
配分額（総額）：5070000, 配分額（直接経費）：3900000, 配分額（間接経費）：1170000
GaInNAsなどの希釈窒化物半導体を用いた発光デバイスの劣化メカニズムを解明するために、結晶成長時に発生する欠陥を透過電子顕微鏡により評価するとともに、結晶にレーザ光を照射し、欠陥の形成・増殖について調べた。その結果、GaInNAs中には点欠陥クラスタ、転位ループなどの欠陥は観察されなかった。また、GaInNAs/GaAs SQW構造にレーザ照射を行うと、レーザパワー密度が低い場合には、発光効率が増加し、パワー密度が高い場合には、発光効率が瞬時に増加後、減少した。いずれの場合にも、特に新たな構造欠陥は形成されず、今後さらなる照射パワー密度の増強を行う必要がある。
競争的資金, 課題番号：26390057 - 非熱平衡状態フォノン輸送制御による半導体光素子の新展開
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 2013年04月01日 - 2017年03月31日
石谷 善博; 篠塚 雄三; 矢口 裕之; 森田 健; 馬 ベイ; 大木 健輔, 千葉大学
配分額（総額）：18720000, 配分額（直接経費）：14400000, 配分額（間接経費）：4320000
半導体素子特性を決める多くの過程にフォノンが関わっている。太陽電池のエネルギー変換効率，励起子の生成・解離，非輻射性キャリア再結合などがこれにあたる。熱平衡状態の詳細な電子・正孔‐励起子系の研究があるが，フォノン系，電子系，輻射場を全て含んだ非熱平衡過程の解析は進んでいない。本研究では，材料物性，素子構造等に基づく素子中のキャリア密度，格子温度などを変数にとり，種々の素過程を統合した電子・正孔や励起子の励起・脱励起の流れを初めて特徴づけることを行った。特に励起子の安定性，非輻射性再結合やキャリアトラップの原因となる深い準位への遷移過程に対するフォノン局在性の影響について新たな知見を得た。
競争的資金, 課題番号：25286048 - 局所ドーピング構造半導体による量子相関光子の生成および制御
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 2012年04月01日 - 2015年03月31日
矢口 裕之; 尾鍋 研太郎; 片山 竜二; 窪谷 茂幸; 土方 泰斗; 八木 修平; 秋山 英文, 埼玉大学, 研究代表者
配分額（総額）：19240000, 配分額（直接経費）：14800000, 配分額（間接経費）：4440000
原子層ドーピングを利用して、窒素原子およびエルビウム原子局所ドーピング構造半導体を作製し、量子情報通信において重要な役割を担う完全ランダム偏光かつ優れた波長再現性を有する単一光子および量子もつれ光子対の高効率生成を目指した。窒素原子局所ドーピング構造半導体を用いて、量子もつれ光子対生成に応用できるランダム偏光の励起子分子および励起子発光の観測に成功した。エピタキシャル成長中のエルビウム原子の表面偏析の温度依存性を定量的に調べることによって、原子層ドーピング構造半導体を作製するための条件として低温成長が必須であることを明らかにした。
競争的資金, 課題番号：24360004
論文ID：17925482 - 炭化ケイ素半導体の酸化誘因欠陥の形成メカニズム解明
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 2012年04月01日 - 2015年03月31日
土方 泰斗; 矢口 裕之, 埼玉大学
配分額（総額）：5460000, 配分額（直接経費）：4200000, 配分額（間接経費）：1260000
炭化ケイ素(SiC)半導体の酸化メカニズムのより深い理解を目指し、1)SiC上の酸化膜構造分析、2)酸化処理基板のフォトルミネッセンス・イメージング観察、3)SiC酸化過程の実時間観察等の実験を行った。
1)の結果から、SiCの酸化時における酸化界面から酸化層への“Si原子放出現象”を世界で初めて観察することに成功した。2)の結果より、積層欠陥が酸化によって変形すること、Si酸化で見られる“酸化誘起積層欠陥”と同様の欠陥がSiCでもまた形成する可能性が示唆された。3)の結果から、統合SiC酸化モデルが構築され、SiおよびC原子の界面濃度から界面欠陥の形成をシミュレーションした。
競争的資金, 課題番号：24560365 - 高相純度立方晶III族窒化物半導体薄膜成長とヘテロ構造の物性応用
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 2010年 - 2012年
尾鍋 研太郎; 矢口 裕之; 片山 竜二; 窪谷 茂幸; サクンタム サノーピン, 東京大学
配分額（総額）：13520000, 配分額（直接経費）：10400000, 配分額（間接経費）：3120000
III族窒化物半導体GaN,InN,AlNおよび関連混晶の高相純度立方晶薄膜およびヘテロ構造を、有機金属気相成長法ないし分子線エピタキシー法を用いて実現し、相純度、欠陥性状、発光特性、電気伝導特性などの基礎物性を成長条件との関連において明らかにした。とくに立方晶InNおよびInGaNにおいてはYSZ(001)基板の有用性を確認した。また立方晶GaNおよびAlGaNにおいては、Si添加による伝導性制御を確立した。立方晶AlNにおいてはバンドギャップ値を同定した。
競争的資金, 課題番号：22360005 - 次世代発光デバイス用新材料および量子ドット構造への光照射劣化の研究
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 2010年 - 2012年
上田 修; 山口 敦史; 佐久間 芳樹; 五神 真; 吉本 昌広; 矢口 裕之; 池永 訓昭, 金沢工業大学
配分額（総額）：3900000, 配分額（直接経費）：3000000, 配分額（間接経費）：900000
発光デバイスの究極の寿命を決定する遅い劣化のメカニズムを解明するために、次世代発光デバイス用の新材料および量子ドット構造に外部から光照射を行い、劣化の度合いを評価した。その結果、新材料のGaInNAsでは、顕著な劣化が見られたが、InGaN,AlInGaAsでは、殆ど劣化が見られなかった。また、InP/InAs量子ドット/InP構造では、比較的強い光励起下でも殆ど劣化は見られなかった。今後、実デバイスに近い構造でも評価する必要がある。
競争的資金, 課題番号：22560012 - 局所ドーピング構造半導体による単一光子発生に関する研究
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 2009年 - 2011年
矢口 裕之; 土方 泰斗; 尾鍋 研太郎; 片山 竜二; 八木 修平; 窪谷 茂幸; 秋山 英文, 埼玉大学, 研究代表者
配分額（総額）：18460000, 配分額（直接経費）：14200000, 配分額（間接経費）：4260000
原子層ドーピング技術を用いて局所ドーピング構造半導体を作製し、量子暗号通信などの量子情報技術において重要となる、優れた波長再現性・完全なランダム偏光などの特徴を有する単一光子発生の実現を目指した。窒素原子局所ドーピング構造半導体の作製に用いる基板面方位の選択によって量子暗号通信への応用にとって望ましい完全なランダム偏光を実現した。また、量子もつれ光子対生成につながる励起子分子発光の観測に成功した。
競争的資金, 課題番号：21360004 - 有機N原料によるInNおよび関連混晶薄膜のMOVPE成長
日本学術振興会, 科学研究費助成事業 特定領域研究, 特定領域研究, 2009年 - 2010年
尾鍋 研太郎; 片山 竜二; 矢口 裕之, 東京大学
配分額（総額）：6400000, 配分額（直接経費）：6400000
本研究課題は、平成19～20年度実施の本特定領域研究公募研究課題の「有機N原料によるInN薄膜のMOVPE成長」の成果を受けて、さらに発展させることを意図した。本研究の特徴は、有機N原料を有機金属原料とともに用いること、さらに原料間の付加化合物生成の寄生反応を避けるために原料の分離供給法を採用することにある。研究期間内において、MOVPE成長InN薄膜の高品質化を伝導性制御も含めて追求するとともに、作製する材料をInGaNおよびInAlNなどInリッチ窒化物混晶へ発展させること、またガス質量分析器を用いて反応系の詳細を明らかにし、寄生反応を回避する有効な反応経路を明らかにすることを目的とした。
最終年度である平成22年度においては、下記各項目に示す成果を挙げた。
1)細管により成長領域へ直接導入するガス種がTMInである場合およびDMHyである場合のそれぞれにおいて、成長特性の成長温度、V/III比、圧力依存性、TMIn供給量依存性を明らかにするとともに、最適細管先端位置の確定、および実効的V/III比など、その決定要因を明らかにした。とくに、成長温度500℃～570℃においてInN成長が効率的に進行することを明らかにした。
2)六方晶InNがサファイア基板上において単一ドメインで、[10-10]InN//[11-20]sapphireのエピタキシャル関係で成長することを、広い成長条件の範囲で確立した。
3)サファイア基板上にGaN層を形成したGaN擬似基板上へのInN成長において、InNウィスカーないしInN微粒子結晶が成長する性状を明らかにした。
4)質量分析器による反応ガス分析システムを活用し、有機N原料として用いるジメチルヒドラジン(DMHy)の熱分解特性を明らかにした。
これらの成果は、InNにもとづく光・電子デバイスを実用化するための高品質InN薄膜を、MOVPEにより実現することの可能性を強く示唆するものとなった。
競争的資金, 課題番号：21016003 - 狭バンドギャップIII-V-N混晶半導体量子ナノ構造の作製と物性応用
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 2007年 - 2009年
尾鍋 研太郎; 片山 竜二; 山本 剛久; 矢口 裕之, 東京大学
配分額（総額）：18720000, 配分額（直接経費）：14400000, 配分額（間接経費）：4320000
InAsN、InGaAsN、InGaPN、InPNなどInをその1成分として含むIII-V-N型混晶半導体による薄膜ないし量子ドット構造をMOVPE法を用いて作製し、結晶成長特性をN濃度との関係において明らかにするとともに、N添加に伴うバンドギャップの縮小効果および発光特性など特徴的な物性を明らかにした。とくにInAsN量子ドットにおいて、波長1.2μmの室温フォトルミネッセンス発光を実現した。本研究により、III-V-N型混晶半導体の物性応用に新規な可能性を示すことができた。
競争的資金, 課題番号：19360003 - 等電子トラップを利用した単一光子発生素子の作製
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 2005年 - 2006年
矢口 裕之; 吉田 貞史; 土方 泰斗, 埼玉大学, 研究代表者
配分額（総額）：3500000, 配分額（直接経費）：3500000
単一光子発生素子は、量子暗号等、量子情報技術の分野で重要な役割を果たすデバイスと考えられている。そこで、本研究では、単一光子発生素子への応用を目指して、窒素原子や窒素原子対によって形成される等電子トラップが、励起子を束縛する効果に着目して、窒素原子対を基本的な単位構造とする半導体量子ナノ構造を作製し、特異な光物性を発現させ、その物理的な解明を行なうことを目的とした。具体的には、原子層ドーピング技術を用いて窒素原子を局所的にドーピングすると同時に、電子線リソグラフィーを用いた微細加工技術によって、特定の配列をした単一の窒素原子対からの発光を観測できるような構造を作製した。母体となる半導体材料にはガリウム砒素およびガリウム燐を用いて、これに極低濃度の窒素原子をドーピングした。特定の配列をした窒素原子対を得るために、窒素原子のドーピング濃度、成長温度や原料の供給比などの最適化を行った。このような構造についての検討の結果、直径1μmの範囲内に特定の配列をした窒素原子対が一つだけ存在するような構造を作製することに成功するとともに、顕微フォトルミネッセンス測定によって線幅が50μeV以下の鋭い発光を得ることに成功した。この結果は、等電子トラップを用いた単一光子発生素子を実現する可能性が十分に高いことを示すものである。また、互いに偏光方向が直交し、わずかにエネルギーの異なる2つの発光線も観測されたことから新規デバイスへの応用も期待される。さらに、素子への応用の上で不可欠となる発光効率を向上させる方法に関して検討を行い、ガリウム砒素・窒素系の混晶半導体において、極低温下でレーザー光を照射することによって発光効率を向上させる独自の方法を確立するとともに、この現象が局所的な構造変化と関連していることを顕微ラマン散乱分光によるその場観察によって明らかにした。
競争的資金, 課題番号：17560004 - IV族半導体の極薄酸化膜の界面評価に関する研究
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 2001年 - 2002年
吉田 貞史; 土方 泰斗; 矢口 裕之, 埼玉大学
配分額（総額）：15300000, 配分額（直接経費）：15300000
分光偏光解析を用いて酸化膜/SiC界面の解析を行うと同時に、酸化膜形成後の種々の熱処理による変化についても調べ、電気的特性との対応について検討した。特に、SiC上の極薄酸化膜の形成過程および界面のミクロ構造を明らかにし、良好なSiC MOS椿造を形成するための知見を得ることを目的として分光偏光解析でその場観察できる装置を開発し、SiCの酸化初期過程や、熱処理による酸化膜/SiC界面の構造変化について研究を行った。その結果、SiCの酸化初期過程においては、SiO2と化学量論組成が異なる酸化膜が形成していることや、SiCやSiO_2よりも大きな屈折率を有する界面層の屈折率が、熱処理によって変化することを見出した。また、γ線照射によって界面準位密度だけを増加させる方法を用いて作製したSiC MOS構造について分光偏光解析とC-V測定とを行うことにより、分光偏光解析でとらえた界面層の屈折率とMOSFETのチャンネル移動度に影響を与える界面準位密度との関係を明らかにした。さらに、角度分解X線光電子分光・紫外光電子分光測定により、熱処理に伴うSiC-SiO_2界面の組成・結合状態の変化を明らかにした。このように、本研究によってSiC-SiO_2界面構造に対する理解が深まるとともに、分光偏光解析法が、界面構造を評価するための優れた方法であることと、その場観察できる方法であることからデバイスプロセスのモニタリングへの応用も可能であることを実証することができた。また、従来SiO_2の光学定数を仮定して行っている酸化膜厚測定法では誤った値を与える問題点があることを初めて明らかにすることができた。偏光解析による評価技術の開発と共に、顕微赤外反射分光を用いてSiCバルク結晶における電気的特性の分布を測定する手法を開発し、ウエハのキャリア濃度および移動度の分布を非破壊・非接触で測定できることを示した。
競争的資金, 課題番号：13450120 - 青色半導体レーザと強誘電体光導波路の一体型新規光学素子のための複合材料創製
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 1998年 - 1999年
増田 淳; 清水 立生; 矢口 裕之; 尾鍋 研太郎; 森本 章治, 北陸先端科学技術大学院大学
配分額（総額）：4000000, 配分額（直接経費）：4000000
青色半導体レーザと酸化物強誘電体光導波路の集積化により、表面弾性波を用いた一体型青色レーザスキャナなどの新規光学素子を開発することを目的に、青色半導体レーザ材料である窒化ガリウム(GaN)上に酸化物強誘電体であるチタン酸ジルコン酸鉛(PZT)薄膜を形成することを試みた。その結果、(100)面のガリウム砒素(GaAs)を基板として、有機金属化学気相成長法で形成したGaN薄膜上に、レーザアブレーション法によりPZT薄膜を形成することに初めて成功した。この際、PZTとGaN間に酸化マグネシウム(MgO)バッファ層を導入することの効果についても検討した。MgOバッファ層はGaN上にcube on cubeの関係でエピタキシャル成長した。MgOバッファ層の導入により、GaN層への酸素の拡散や、PZTとGaN間の金属元素の相互拡散が抑制できることを見出した。さらに、MgOバッファ層を用いない場合にはPZT薄膜はランダム配向であったが、MgOバッファ層の導入により[100]優先配向PZT薄膜が得られた。
次に、GaNの結晶性と耐酸化性の相関を、六法晶混在比の大きい試料、X線回折の半値幅の大きい試料ならびに高品質試料の3種類のGaN薄膜の比較により検討した。その結果、結晶性の劣るGaN薄膜の方が耐酸化性に優れることを見出した。また、酸素雰囲気曝露により、GaN薄膜の結晶性が劣化し、表面粗さは減少することも明らかになった。
競争的資金, 課題番号：10650005 - 分極反転エピタクシーの研究と波長変換素子への応用
日本学術振興会, 科学研究費助成事業 基盤研究(A), 基盤研究(A), 1996年 - 1998年
伊藤 良一; 宇佐美 徳隆; 矢口 裕之; 近藤 高志; 尾鍋 研太郎; 白木 靖寛, 東京大学
配分額（総額）：41700000, 配分額（直接経費）：41700000
1. 分極反転エピタクシーの実証
GaAs/Si/GaAs(100),GaAP/Si/GaP(100),GaAs/Ge/GaAs(100),GaAs/Ge/GaAs(111)の系についていずれも分極反転エピタクシーが実現できることを実証した。MBEを用いた結晶成長で再現性良く分極反転を実現できる条件を見出した。分極反転の確認にはRHEEDと異方性エッチングが有効であった。
2. 分極反転エピタクシャル膜の評価
反射SHG測定によって分極反転エピタクシー法で成長したエピ膜の非線形光学定数の符合が確かに反転していることを確認した。また,X線定在波法によっても分極反転の有無が確認できることを示した。XTEM観察によってアンチフェイズドメインの挙動を観察することに成功し,RHEED観察の結果とあわせて,副格子交換のメカニズムを解明することができた。さらに興味深い現象として,GaAs/Ge/GaAs(111)において現状では異常な(111)Σ3粒界が存在することがXTEM観察によって判明した。
3. 周期分極反転構造の作製
GaAs/Ge/GaAs(100)系分極反転エピタクシーの手法を用いて周期的分極反転構造AlGaAsデバイスを作製する方法を考案した。成長の初期過程でアンチフェイズドメインが発生してもデバイス部に影響を与えることなく成長がおこなえる点が大きな特徴である。MBEによる再成長によって非常に良質な周期分極反転構造を作製することに成功した。現在,この技術を用いて導波路型波長変換デバイスの試作をおこなっているところである。
競争的資金, 課題番号：08405002 - 新しい超構造を有する間接遷移型半導体の光学遷移に関する研究
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 1996年 - 1997年
白木 靖寛; 宇佐美 徳隆; 矢口 裕之; 近藤 高志; 尾鍋 研太郎; 伊藤 良一, 東京大学
配分額（総額）：8600000, 配分額（直接経費）：8600000
本研究においては、間接遷移型半導体に、さまざまな超構造を導入するとこにより、材料固有の性質を人為的に変化させ、光学遷移確率を増大させることを、SiGe/Si系、AlGap系という、二種類の典型的な間接遷移型半導体に対して試みた。特に、電子と正孔を空間的に分離して閉じ込める「隣接閉じ込め構造」について詳しく検討した。
緩和SiGeバッファ上に、引っ張り歪みSi層と、圧縮歪みSiGe層を交互に成長することにより形成した、SiGe/Si系隣接閉じ込め構造においては、正孔の閉じ込め層の膜厚を、島状成長の臨界膜厚程度に選ぶことにより、無フォノン発光の効率を増加させることができることがわかった。これは、臨界膜厚付近では、島形成の核となるような、井戸幅のゆらぎが多く存在するため、界面における励起子の局在が、顕著になるからである。
また、AlGap系隣接閉じ込め構造に関しては、歪みを加えることにより、歪みゆらぎに起因した、面内ポテンシャルのゆらぎにより、無フォノン発光強度が増大することがわかっていたが、時間分解フォトルミネッセンス法により、この事実を検証した。パルスレーザで励起した場合のピークエネルギーの時間依存性は、いずれの試料においても、時間とともに、ピークエネルギーがレッドシフトした。これは、NCSの活性層に緩和した励起子が、時間とともに、より深い面内ポテンシャルくぼみに束縛されることを示している。歪みが印加された試料では、ピークエネルギーのレッドシフト量が非常に大きくなることから、歪みの大きい試料ほど深いポテンシャルくぼみが形成されているとが示された。
競争的資金, 課題番号：08455008 - シリコン・ゲルマニウム規則混晶からの光第二高調波発生に関する研究
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 1996年 - 1996年
矢口 裕之; 近藤 高志, 東京大学, 研究代表者
配分額（総額）：2200000, 配分額（直接経費）：2200000
Si分子線セルの検討
固体ソースSi分子線エピタキシャル成長では,従来Siを蒸発させる手段として電子銃加熱が用いられてきたが成長速度の安定性に問題があり,成長速度の制御も容易ではない。そこでこれに代わる方法として,高温まで使用可能なSi分子線セルを用いてSiGeヘテロ構造の作製を行った。Si分子線セルは1350〜1650℃の範囲で使用した。これは5×10^<-3>〜0.5Å/secの成長速度に対応し、2桁にわたって成長速度の制御が可能であることがわかった。分子線セルでは成長速度の制御性が高く,本研究で対象とする短周期超格子構造の作製に最適な成長技術を確立することができた。
Si/Ge短周期超格子からの光第二高調波発生
SiおよびGeは反転対称性を有するため双極子近似による光第二高調波発生は禁止されているが,奇数原子層からなるSi_nGe_n超格子においては反射対称性が崩れるための光第二高調波発生が期待される。本研究ではSi(111)基板上にSi_3Ge_3超格子を作製し、光第二高調波の測定を行い,超格子からの寄与と考えられる光第二高調波発生を初めて観測した。この試料を850℃でアニールすると光第二高調波の強度が急激に減少した。これはアニールによって原子の拡散が起こり、超格子構造が壊れたためと考えられる。比較のために反転対称性を有するSi_4Ge_4超格子で同様の測定を行った結果,光第二高調波の強度は弱く,アニールによる強度変化はほとんどなかった。しかたがってこの場合の光第二高調波は表面からの寄与によると考えられる。
今後は,成長中に形成される規則混晶からの光第二高調波発生について研究を進めたいと考えている。
競争的資金, 課題番号：08650005 - 非対称構造半導体量子井戸の2次非線形光学特性の研究
日本学術振興会, 科学研究費助成事業 基盤研究(C), 基盤研究(C), 1996年 - 1996年
近藤 高志; 矢口 裕之, 東京大学
配分額（総額）：2200000, 配分額（直接経費）：2200000
1.参照用試料(GaAs)の評価
AlGaAs量子井戸の非線形光学特性の評価時に用いるGaAsの非線形光学定数の絶対値を最初に測定した。発振波長1.533μmのDFBレーザを基本波光源としてSHG法によって絶対測定をおこない,d_<36>=119pm/Vという結果を得た。
2.電場印加AlGaAs量子井戸の評価
バルクGaAsとのSHG相対測定によって電場印加AlGaAs非対称量子井戸の非線形光学定数の測定をおこなった。測定に用いた試料はGaAs(100)基板上に成長した多重量子井戸で,Al_<0.18>Ga_<0.82>As井戸層(井戸幅10nm)とAl_<0.30>Ga_<0.70>As障壁層(障壁層幅5nm)とを47周期積層したものである。基本波光源としてFP型GaInAsPレーザにグレーティングフィードバックをかけた外部共振器型の波長可変半導体レーザを用いて,励起子順位からのdetuning(ΔE=E_-2hw)と試料に印加する電場(E_ )とをパラメータとして測定をおこなった。測定の結果,ΔE=9.9meV,E_ =59kV/cmで最大d_<15>=16pm/Vというかなり大きな値が得られた。しかしながら,これは単一量子井戸についておこなわれた理論計算の結果(d_<15>=60pm/V)よりも小さく,理論計算で無視していた井戸間の相互作用が影響しているものと考えられる。
以上の研究を通じて、非対称構造半導体量子井戸の近赤外域での2次非線形光学特性を初めて定量的に評価することができた。今後は,光通信への応用を念頭に置いて差周波発生の実験をおこなっていきたいと考えている。
競争的資金, 課題番号：08650045 - 窒化物系準安定混晶半導体の作製と物性に関する研究
日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 1994年 - 1996年
尾鍋 研太郎; 矢口 裕之; 近藤 高志; 長田 俊人; 白木 靖寛; 伊藤 良一; 深津 晋, 東京大学
配分額（総額）：8400000, 配分額（直接経費）：8400000
本研究は、極度の非混和性を有するために従来作製が困難であったGaPNに代表されるIII-V-N型の窒化物系混晶半導体の作製および物性解明を行ったものである。本研究により以下の諸点が明らかになり、これらの特徴的な物性を利用した新しい工学的応用に道を拓くものである。 1.【GaPN混晶の結晶成長】N原料としてジメチルヒドラジンを用いたGaPN混晶の有機金属気相成長における成長特性を明らかにした。とくに混晶組成はN原子の結晶成長表面からの再脱離過程に大きく支配されることが明らかになった。これらの成長特性に基づき、N組成が6%までのGaPN混晶の実現に成功した。 2.【発光準位の起源と性質】窒素濃度が4%までのGaPN混晶における、光吸収、フォトルミネッセンス、および励起スペクトルなどの光学測定および解析により、発光準位はバンド端の状態密度テイル部に形成される準局在準位に基づいていることが明らかになった。極低温における発光の緩和過程は、N組成1%以下ではNN対に基づく発光緩和、N組成1%以上では非発光準位および準局在発光準位への緩和が支配的となる。 3.【N組成の増加におけるバンド端の形成過程】GaPN混晶のバンド端は、GaP結晶中に孤立して存在するN原子に起因する準位により形成されるものであることが明らかになった。さらに局在励起子の擬自由励起子への活性化による移動度端のふるまいが明らかになった。これらは併せて行った強結合近似に基づくバンド計算の結果と整合するものであり、エネルギーギャップの組成依存性における巨大ボウイング効果がGaPN混晶の本来の特徴的な性質であることを示している。またこの性質は、GaAsPN、InGaPNなどの関連混晶において共通の特性であることを示唆している。
競争的資金, 課題番号：06452107 - 歪導入による半導体量子ナノ構造の偏光特性の制御
日本学術振興会, 科学研究費助成事業 一般研究(C), 一般研究(C), 1995年 - 1995年
矢口 裕之, 東京大学, 研究代表者
配分額（総額）：2500000, 配分額（直接経費）：2500000
本研究の主たる目的は,引っ張り歪の導入によって半導体量子細線構造における発光の偏光特性の制御が可能であることを実証することにある。そこでまず最初にGaAsP/AlGaAs量子井戸を作製し,引っ張り歪を導入して発光の偏光特性を制御できることを実験的に検証した。
本研究では,フォトリソグラフィー技術で基板にV溝状の加工を施した後,有機金属気相エピタキシ-法によって量子細線構造を作製するという方法をとっている。この場合,AlGaAs障壁層を成長する際にはV溝の形状を鋭く保ち,一方,GaAsPからなる細線層を成長する際にはV溝の底部に厚く成長することが要求される。そこで良好な形状を有する細線構造を作製する成長条件を決定することが重要な位置を占める。その過程においてV溝底部にGa組成の大きいAlGaAs混晶が局所的に成長することがわかった。また,その部分の寸法が成長温度・Al供給量等の成長条件に依存することが明らかになり,これに基づく新しい量子細構造作製の提案を行った。さらに最適な成長条件に基づいてGaAsP/AlGaAs引っ張り歪量子細線構造を作製した。フォトルミネッセンスによって発光の偏光特性を検討した結果,細線の寸法を小さくするにしたがって,基板に平行な偏光から基板に垂直な偏光へと変化していくことが明らかになり,歪導入によって偏光の制御が可能であることが実証された。
以上の実験結果に基づいて細線の寸法を決定し,量子細線方向と垂直な方向に対して偏光の異方性が解消された量子細線構造レーザを試作した。電流注入量が発振しきい値下では偏光の異方性のほとんどない発光が確認された。レーザ特性としてはしきい値電流が高いなどの問題があり,さらに今後の検討を要する。
競争的資金, 課題番号：07650005 - ガリウム砒素リン系半導体超格子構造による高効率発光素子材料の実現
日本学術振興会, 科学研究費助成事業 一般研究(C), 一般研究(C), 1994年 - 1994年
矢口 裕之; 白木 靖寛; 尾鍋 研太郎, 東京大学, 研究代表者
本研究で取り扱った砒素リン系半導体超格子構造においては、ガリウム砒素に近い組成領域では室温でレーザ発振するほどの高品質なものが得られているが、ガリウムリンに近い組成領域では間接遷移型半導体であり、しかもバンドラインアップが、電子と正孔が別々に閉じ込められるようなタイプIIであるという実験結果があるために、高効率の発光材料としては適当ではないと考えられてきた。
しかしながら、フォトリフレクタンス分光法およびフォトルミネッセンス分光法を用いることによって、ガリウムリン基板上に超格子構造を作製した場合には、ガリウムリン・ガリウム砒素リンヘテロ界面はどのような組成領域においてもタイプIとなることがわかった。さらに本研究によって、すべての組成領域において直接遷移エネルギーギャップ、間接遷移エネルギーギャップのどちらについてもタイプIヘテロ構造が実現されていることが初めて明らかになった。
また、基板にガリウム砒素リンを用いて、ガリウム砒素・ガリウムリン超格子を作製し、どちらの層にも歪が加わるようにした。この場合、間接遷移バンドの縮退が解けてタイプIとタイプIIの両方のヘテロ構造が同時に存在するような極めて興味深い状況が実現することがわかった。実際に両方の光学遷移に対応するフォトルミネッセンスが観測され、発光寿命にもタイプIとタイプIIの違いが反映されることが明らかになった。
以上、高効率にするために不可欠な基礎物性に関する十分な知見を得ることが出来た。
競争的資金, 課題番号：06650005 - フォトリフレタンス分光法による間接遷移型半導体を材料とした超構造半導体の研究
日本学術振興会, 科学研究費助成事業 奨励研究(A), 奨励研究(A), 1993年 - 1993年
矢口 裕之; 鳥山 欽哉, 研究代表者
配分額（総額）：900000, 配分額（直接経費）：900000
量子井戸レーザや高速トランジスタは半導体のヘテロ構造を利用することによってその特性を引き出しているが、これらのデバイスを設計する上で重要な基本的物性であるヘテロ界面でのバンド不連続量等に関する情報は不可欠である。本研究ではフォトリフレクタンス分光法を用いてこのような基本的物性を間接遷移型半導体について検討し、さらに界面の平坦性についても検討を行った。その結果、
1.高速トランジスタへの応用が期待されるゲルマニウム/シリコン・ゲルマニウム界面でのバンド不連続量を明らかにした。そして、バンド不連続量はゲルマニウム組成に対して線形に変化することがわかった。さらに、フォトリフレクタンス・スペクトルの線幅に注目することによって、界面の平坦性について検討を行い、横方向数百Aの範囲では1原子層程度の凹凸が存在することが明らかになった。
2.発光材料として用いられるガリウム砒素燐系の中で、広いバンドギャップを有するガリウム燐に近い組成でのヘテロ界面におけるバンド不連続量を明らかにした。フォトリフレクタンスによって明らかになったのはGAMMA点におけるバンド不連続量であるが、この結果に基づいて、最小ギャップを形成しているX点におけるバンド不連続量を導き出し、そのバンドラインアップがtypeIになっていることを明らかにした。このことはフォトルミネッセンス測定による結果からも確かめられた。
3.電場変調用の励起光として波長連続可変光源を用いて量子井戸層のみを励起し、量子井戸構造の局所的な情報を得るという新しい手法の検討を行った結果、励起光波長依存性が測定温度によって大きく異なることがわかった。その原因の解明にはより詳細な研究が不可欠である。
競争的資金, 課題番号：05750003 - ナイトライド系化合物半導体の立方晶構造変換ヘテロエピタキシー機構の研究
日本学術振興会, 科学研究費助成事業 重点領域研究, 重点領域研究, 1992年 - 1992年
尾鍋 研太郎; 矢口 裕之; 近藤 高志; 深津 晋; 白木 靖寛; 伊藤 良一, 東京大学
配分額（総額）：1700000, 配分額（直接経費）：1700000
本年度は、GaAsないしGaP上への立方晶GaNおよび関連の混晶のMOVPE成長と結晶評価を行い、以下の成果を得た。
1)GaAs上の不純物添加のない立方晶GaNにおいて、従来困難とされていたp型電気伝導特性を見い出した。再現性およびp型伝導の起源についての検討を進め、結晶粒界などの結晶性状に由来するものとの見通しを得た。
2)SiO_2をマスクとして用いたGaAs上の5μm平方の微小領域への立方晶GaNのMOVPE成長において、単結晶領域のサイズが基板全面への通常の成長の場合に比べて数倍程度大きくなることを見い出した。
3)立方晶GaN/GaAs界面の高分解能透過型電子顕微鏡による直接観察により、界面が(100)B面より成ること、また界面に直接接してほとんど無歪みの立方晶GaNが形成されているなどの界面微構造を明らかにした。
4)GaAsおよびGaP上にGaAsNおよびGaPN混晶のMOVPE成長を行い、GaAsNにおいて最大N濃度0.5%、GaPNにおいて同2.9%の混晶を得ることに成功した。またフォトルミネッセンスにより発光ピークエネルギーがN濃度の増加により長波長化することを見い出した。またラマン分光により混晶の結晶性評価を行い、混晶化によるラマンシフトを見い出した。
以上によりGaNにおける立方晶構造変換ヘテロエピタキシーの基本的特性が明らかになり、結晶成長機構を解明する上での有力な知見を得た。
課題番号：04227211 - 有機金属気相成長法によるワイドギャップ化合物半導体の原子層エピタキシ-の研究
日本学術振興会, 科学研究費助成事業 一般研究(B), 一般研究(B), 1989年 - 1991年
尾鍋 研太郎; 矢口 裕之; 近藤 高志; 深津 晋; 白木 靖寛; 伊藤 良一, 東京大学
配分額（総額）：7400000, 配分額（直接経費）：7400000
本研究では、GaAsP系量子井戸および立方晶GaNに関して結晶成長および材料評価を進め、結晶成長上の特性および材料物性について新知見を得た。
1.GaAs/GaAsPヘテロ構造に基づく歪み量子井戸構造および歪み障壁量子井戸構造を作製し、フォトルミネッセンス、赤外反射分光およびフォトリフレクタンスによる光学的評価より、ヘテロ界面におけるバンド不連続値の決定を行った。これにより、バンド不連続値の混晶組成比および歪み依存性が明らかになった。
2.GaAsP/GaPヘテロ構造に基づく歪み多重量子井戸構造を作製し、フォトリフレクタンスによる光学的評価より、ヘテロ界面におけるバンド不連続値の決定を行った。これにより量子井戸構造が第1型に属するものであることが明らかになった。またフォトルミネッセンスによる評価より、間接遷移に基づく発光を観測した。
3.GaN結晶成長のV族(N)原料ガスとして、ジメチルヒドラジンを用いてサファィアおよびGaAs結晶基板上への成長を行い、従来のアンモニア使用に比較して、低温かつ高効率の結晶成長条件を確立した。
GaAs上へのGaN結晶成長においては、従来より完全性の高い立方晶結晶を厚さ1μmにわたり得ることに成功し、当初の目的であった「結晶構造変換ヘテロエピタキシ-」を基本的に実証した。さらに、X線回折およびラマン分光法による詳細な構造的評価を進め、立方晶GaNの構造的特性について明らかにした。また光学的・電気的評価より立方晶GaNのバンドギャップ、n型およびp型導電特性について明らかにした。
今後は、GaAsP系量子井戸および立方晶GaNに関するこれらの新知見に基づいて、材料作製の方法にさらに高度の改良を加えるとともに、可視光領域の発光特性・非線形光学的特性の評価、およびフォトニックデバイスへの応用への検討を進める計画である。
課題番号：01460071 - -
競争的資金
- 光起電力素子及びその製造方法
佐藤 大典; 矢口 裕之; 八木 修平, 特許権
特許番号・登録番号：特許第5841231号
J-Global ID：201603019885568991 - 光起電力素子及びその製造方法
佐藤 大典; 矢口 裕之; 八木 修平, 特許権
J-Global ID：201503010382867768 - 多孔質酸化チタン薄膜とその製造方法
八巻 徹也; 伊藤 久義; 篠原 竜児; 浅井 圭介; 阿部 弘亨; 土方 泰斗; 矢口 裕之, 特許権
特許番号・登録番号：特許第4104899号
J-Global ID：201103066300269030 - 多孔質酸化チタン薄膜とその製造方法
八巻 徹也; 伊藤 久義; 篠原 竜児; 浅井 圭介; 阿部 弘亨; 土方 泰斗; 矢口 裕之, 特許権
J-Global ID：200903052376790857