業績情報

• 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, 2025年02月, ［査読有り］
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1063/5.0247676
  DOI ID：10.1063/5.0247676, ORCID：177570673
• 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 GaP_1−xN_x 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
• 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］, ［筆頭著者］
  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, 英語, 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, 共同研究・競争的資金等ID：40969023
• Activation of two dopants, Bi and Er in δ-doped layer in Si crystal
  Murata, K.; Yagi, S.; Kanazawa, T.; Tsubomatsu, S.; Kirkham, C.; Nittoh, K.-I.; Bowler, D.R.; Miki, K.
  Nano Futures, 巻：5, 号：4, 開始ページ：045005, 終了ページ：045005, 2021年12月, ［査読有り］
  Abstract
  
  Conventional doping processes are no longer viable for realizing extreme structures, such as a δ-doped layer with multiple elements, such as the heavy Bi, within the silicon crystal. Here, we demonstrate the formation of (Bi + Er)-δ-doped layer based on surface nanostructures, i.e. Bi nanolines, as the dopant source by molecular beam epitaxy. The concentration of both Er and Bi dopants is controlled by adjusting the amount of deposited Er atoms, the growth temperature during Si capping and surfactant techniques. Subsequent post-annealing processing is essential in this doping technique to obtain activated dopants in the δ-doped layer. Electric transport measurement and photoluminescence study revealed that both Bi and Er dopants were activated after post-annealing at moderate temperature.
  IOP Publishing, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1088/2399-1984/ac421d
  DOI ID：10.1088/2399-1984/ac421d, ISSN：2399-1984, eISSN：2399-1984, ORCID：127971459, SCOPUS ID：85140874876
• 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-BASIC SOLID STATE PHYSICS, 巻：258, 号：11, 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 (x=0.75%), 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-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pssb.202100119
  DOI ID：10.1002/pssb.202100119, ISSN：0370-1972, eISSN：1521-3951, Web of Science ID：WOS:000692804600001
• 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, Web of Science ID：WOS:000567593300001
• Spectral Change of E − Band Emission in a GaAs:N δ-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］
  © 2019, The Minerals, Metals & Materials Society. In this study, we examined the E− band luminescence of a GaAs:N δ-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 (P2) at 1.38 eV of the E− band was quenched larger compared to the high-energy peak (P1) 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 P1 was quenched higher compared to the low-energy peak P2 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 δ-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, SCOPUS ID：85075954109, Web of Science ID：WOS:000500279100002
• Photoluminescence characterization of nonradiative recombination centers in MOVPE grown GaAs:N δ-doped superlattice structure
  Haque, M.D.; Kamata, N.; Islam; A.Z.M.T.; Honda, Z.; Yagi, S.; Yaguchi, H.
  Optical Materials, 巻：89, 開始ページ：521, 終了ページ：527, 2019年02月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.optmat.2019.01.047
  DOI ID：10.1016/j.optmat.2019.01.047, ISSN：0925-3467, ORCID：127971375, SCOPUS ID：85061552945
• 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 Research, 2019年, ［査読有り］
  © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 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：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85074068004&origin=inward
  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, SCOPUS ID：85074068004, Web of Science ID：WOS:000489972400001
• 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, ［査読有り］, ［責任著者］
  © 2019 The Japan Society of Applied Physics. 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° and 3.5° 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.
  IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.7567/1347-4065/ab106a
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85070734869&origin=inward
  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, SCOPUS ID：85070734869, Web of Science ID：WOS:000474911400059
• Effects of solvent vapor annealing on organic photovoltaics with a new type of solution-processable oligothiophene-based electronic donor material　　　　　　　　　　　　　　　
  Akiyama, Yuki; Tachibana, Hiroaki; Azumi, Reiko; Miyadera, Tetsuhiko; Chikamatsu, Masayuki; Koganezawa, Tomoyuki; Yagi, Shuhei; Yaguchi, Hiroyuki
  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
  DOI ID：10.7567/JJAP.57.08RE09, ISSN：0021-4922, eISSN：1347-4065, 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
  DOI ID：10.1002/pssb.201700454, ISSN：0370-1972, eISSN：1521-3951, Web of Science ID：WOS:000432028400019
• Nonradiative recombination centers in GaAs:N delta-doped superlattice revealed by two-wavelength-excited photoluminescence　　　　　　　　　　　　　　　
  Haque, Md. Dulal; Kamata, Norihiko; Fukuda, Takeshi; Honda, Zentaro; Yagi, Shuhei; Yaguchi, Hiroyuki; Okada, Yoshitaka
  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
  DOI ID：10.1063/1.5011311, ISSN：0021-8979, eISSN：1089-7550, Web of Science ID：WOS:000431147200029
• Growth of InN/GaN dots on 4H-SiC(0001) 4° off vicinal substrates by molecular beam epitaxy　　　　　　　　　　　　　　　
  Keisuke Matsuoka; Shuhei Yagi; Hiroyuki Yaguchi
  Journal of Crystal Growth, 巻：477, 開始ページ：201, 終了ページ：206, 2017年11月, ［査読有り］
  © 2017 Elsevier B.V. We have fabricated self-assembled InN dots on GaN using 4H-SiC(0001) vicinal substrates (4° 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.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jcrysgro.2017.05.021
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  DOI ID：10.1016/j.jcrysgro.2017.05.021, ISSN：0022-0248, SCOPUS ID：85020105871, Web of Science ID：WOS:000413646100043
• Spectral change of intermediate band luminescence in GaP:N due to below-gap excitation: Discrimination from thermal activation　　　　　　　　　　　　　　　
  N. Kamata; M. Suetsugu; D. Haque; S. Yagi; H. Yaguchi; F. Karlsson; P. O. Holtz
  Physica Status Solidi (B) Basic Research, 巻：254, 号：2, 2017年02月, ［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
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  DOI ID：10.1002/pssb.201600566, ISSN：0370-1972, eISSN：1521-3951, SCOPUS ID：85003749566, Web of Science ID：WOS:000394614300035
• 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 Research, 巻：254, 号：2, 2017年02月, ［査読有り］, ［責任著者］
  © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 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° 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.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pssb.201600542
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  DOI ID：10.1002/pssb.201600542, ISSN：0370-1972, eISSN：1521-3951, SCOPUS ID：85000938311, Web of Science ID：WOS:000394614300028
• Photoluminescence characterization of carrier recombination centers in 4H-SiC substrates by utilizing below gap excitation　　　　　　　　　　　　　　　
  K. Kondo; N. Kamata; H. Yaguchi; S. Yagi; T. Fukuda; Z. Honda
  Materials Science Forum, 巻：897 MSF, 開始ページ：315, 終了ページ：318, 2017年, ［査読有り］
  © 2017 Trans Tech Publications, Switzerland. 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.
  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.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：0255-5476, eISSN：1662-9752, SCOPUS ID：85020048562
• Photoluminescence study of oxidation-induced faults in 4H-SiC epilayers　　　　　　　　　　　　　　　
  Yutaro Miyano; Ryosuke Asafuji; Shuhei Yagi; Yasuto Hijikata; Hiroyuki Yaguchi
  AIP Advances, 巻：5, 号：12, 2015年12月, ［査読有り］
  © 2015 Author(s). 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.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1063/1.4938126
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  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, SCOPUS ID：84952672264, Web of Science ID：WOS:000367596300016
• Control of intermediate-band configuration in GaAs:N δ-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, 2015年08月, ［査読有り］
  © 2015 The Japan Society of Applied Physics. GaAs:N δ-doped superlattices (SLs) consisting of alternating layers of undoped and N δ-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 δ-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 δ-doped SLs.
  IOP PUBLISHING LTD, 英語, 研究論文（国際会議プロシーディングス）
  DOI：https://doi.org/10.7567/JJAP.54.08KA04
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  DOI ID：10.7567/JJAP.54.08KA04, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：84938516127, Web of Science ID：WOS:000358662900005
• Molecular beam epitaxial growth of intermediate-band materials based on GaAs:N δ-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, 2015年08月, ［査読有り］, ［責任著者］
  © 2015 The Japan Society of Applied Physics. We fabricated GaAs:N δ-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 δ-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.
  IOP PUBLISHING LTD, 英語, 研究論文（国際会議プロシーディングス）
  DOI：https://doi.org/10.7567/JJAP.54.08KA07
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  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, SCOPUS ID：84938504709, Web of Science ID：WOS:000358662900008
• 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, 2015年03月, ［査読有り］
  © 2015 AIP Publishing LLC. 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 ¯0) a-face, and (000 1 ¯) 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.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1063/1.4914050
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  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, SCOPUS ID：84924310120, Web of Science ID：WOS:000351134400041
• Photoluminescence study of oxidation-induced stacking faults in 4H-SiC epilayers　　　　　　　　　　　　　　　
  Yutaro Miyano; Shuhei Yagi; Yasuto Hijikata; Hiroyuki Yaguchi
  Materials Science Forum, 巻：821-823, 開始ページ：327, 終了ページ：330, 2015年, ［査読有り］
  © (2014) Trans Tech Publications, Switzerland. We have investigated the effect of thermal oxidation on stacking faults (SFs) in 4H-SiC epilayers using photoluminescence imaging. We found that a comb-shaped dislocation array was deformed by thermal oxidation and that SFs were formed on both sides of the comb-shaped dislocation array by a laser irradiation. Transmission electron microscopy has been performed in the comb-shaped dislocation array to observe the stacking pattern of SF near the dislocation. As a result, the SF turned out to be a single Shockley SF (1SSF). We also found that line-shaped faults perpendicular to the off-cut direction were formed during oxidation and were stretched with oxidation time. Moreover, triangle-shaped SFs were formed/expanded from the line-shaped faults by a laser irradiation. The characteristics of these line-shaped faults were discussed.
  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.821-823.327
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  DOI ID：10.4028/www.scientific.net/MSF.821-823.327, ISSN：0255-5476, SCOPUS ID：84950321920
• Surface orientation dependence of SiC oxidation process studied by in-situ spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Daisuke Goto; Shuhei Yagi; Yasuto Hijikata; Hiroyuki Yaguchi
  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.
  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.821-823.371
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  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, SCOPUS ID：84950341587
• 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, 2015年, ［査読有り］
  © 2015 The Japan Society of Applied Physics. 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 °C and above and that the segregation decay length is approximately 0.5μm at 500 °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°C is effective in suppressing the surface segregation of Er and obtaining δ-doped structures.
  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, SCOPUS ID：84983072013, Web of Science ID：WOS:000354980300009
• Enhanced optical absorption due to E+-related band transition in GaAs:N δ-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］
  © 2014 The Japan Society of Applied Physics. The photoabsorption characteristics of GaAs:N δ-doped superlattices (SLs) are investigated. Periodic insertion of N δ-doped layers into GaAs induces the formation of conduction subbands E+ and E-, and each conduction subband forms SL minibands with the GaAs conduction band between the δ-doped layers. In addition to an optical absorption related to the E- band, an abrupt absorption edge originating from the electron transition between the valence band and an E+-related miniband is observed at 1.6eV in a photoluminescence excitation (PLE) spectrum, indicating that GaAs:N δ-doped SLs are promising candidates for the absorber of intermediate-band solar cells.
  IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.7567/APEX.7.102301
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  DOI ID：10.7567/APEX.7.102301, ISSN：1882-0778, eISSN：1882-0786, SCOPUS ID：84988891884, Web of Science ID：WOS:000344439300007
• Photoreflectance study of the temperature dependence of excitonic transitions in dilute GaAsN alloys
  Okubo, W.; Yagi, S.; Hijikata, Y.; Onabe, K.; Yaguchi, H.
  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03月, ［査読有り］
  英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pssa.201300462
  DOI ID：10.1002/pssa.201300462, ISSN：1862-6319, ORCID：127971457, SCOPUS ID：84897986009
• Si emission into the oxide layer during oxidation of silicon carbide　　　　　　　　　　　　　　　
  Yasuto Hijikata; Yurie Akasaka; 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］
  To verify the Si emission phenomenon during oxidation of SiC, the behavior of Si atoms was investigated using HfO2/SiC structures. At low oxygen pressure, i.e. the oxidation condition predominant to active oxidation, Si emission into oxide layer and the growth of SiO2 on the oxide surface were clearly observed by TOF-SIMS. On the other hand, the growth of SiO2 on the surface was suppressed under an ordinary pressure. These results evidence the Si emission during oxidation that is proposed in the Si and C emission model. © (2014) 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/MSF.778-780.553
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84896066589&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.778-780.553, ISSN：0255-5476, eISSN：1662-9752, SCOPUS ID：84896066589, Web of Science ID：WOS:000336634100130
• 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, 巻：10, 号：11, 開始ページ：1545, 終了ページ：1548, 2013年11月, ［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-N2 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. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pssc.201300275
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  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, SCOPUS ID：84887619549, Web of Science ID：WOS:000334583400049
• Conversion efficiency of intermediate band solar cells with GaAs:N δ-doped superlattices　　　　　　　　　　　　　　　
  Shuhei Yagi; Shunsuke Noguchi; Yasuto Hijikata; Shigeyuki Kuboya; Kentaro Onabe; Hiroyuki Yaguchi
  Japanese Journal of Applied Physics, 巻：52, 号：10 PART1, 2013年10月, ［査読有り］
  The performance of intermediate band solar cells using a GaAs:Nλ-doped superlattice (SL) as the optical absorber is analyzed. In GaAs:Nβ-doped SLs, both of the E+ and E- bands formed around the Nλ-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 Eλ- 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:Nλ-doped SL is a possible way to further facilitate the development of intermediate band materials for highefficiency solar cells. © 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, SCOPUS ID：84887232116, Web of Science ID：WOS:000325209000024
• 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. © 2013 The Japan Society of Applied Physics.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.7567/APEX.6.092401
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  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, SCOPUS ID：84883664354, Web of Science ID：WOS:000324494100020
• 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
  Materials Science Forum, 巻：740-742, 開始ページ：833, 終了ページ：836, 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. © (2013) 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/MSF.740-742.833
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  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, eISSN：1662-9752, SCOPUS ID：84874076989, Web of Science ID：WOS:000319785500198
• Molecular beam epitaxy of ErGaAs alloys on GaAs (0 0 1) 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, ［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. © 2012 Elsevier B.V. All rights reserved.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.043
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  DOI ID：10.1016/j.jcrysgro.2012.12.043, ISSN：0022-0248, SCOPUS ID：84885427998, Web of Science ID：WOS:000323355900023
• 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, ［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 (001) substrates by RF-N2 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 2.2×1011 cm-2 was successfully obtained at a growth temperature of 470 °C and an In flux of 7.0×10-5 Pa. © 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
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  DOI ID：10.1016/j.jcrysgro.2012.12.050, ISSN：0022-0248, eISSN：1873-5002, SCOPUS ID：84885434999, Web of Science ID：WOS:000323355900113
• Analysis of electronic structures of nitrogen δ-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, ［査読有り］
  Nitrogen δ-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 δ-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 δ-doped GaAs SLs are expected to be an excellent alternative to uniformly doped GaAsN alloys for the use in intermediate band solar cells. © 2011-2012 IEEE.
  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, SCOPUS ID：84884672481, Web of Science ID：WOS:000324881400023
• 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：539, 2013年, ［査読有り］
  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. © 2013 AIP Publishing LLC.
  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/10.1063/1.4848523
  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, SCOPUS ID：84907305933, Web of Science ID：WOS:000331793000268
• Biexciton luminescence from individual isoelectronic traps in nitrogen δ-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, 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 δ-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. © 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, SCOPUS ID：84869186070, Web of Science ID：WOS:000310867800003
• 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, 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 4 H-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. © 2012 American Institute of Physics.
  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, 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, 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: ∼425.5nm) 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. © 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, SCOPUS ID：84861398046, Web of Science ID：WOS:000303932500005
• 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, 巻：9, 号：3-4, 開始ページ：658, 終了ページ：661, 2012年03月, ［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° 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 a -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. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  WILEY-V C H VERLAG GMBH, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pssc.201100365
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84858842029&origin=inward
  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, SCOPUS ID：84858842029, Web of Science ID：WOS:000306521600059
• 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
  Materials Science Forum, 巻：706-709, 開始ページ：2916, 終了ページ：2921, 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. © 2012 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.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, eISSN：1662-9752, SCOPUS ID：84856180201, Web of Science ID：WOS:000308517301220
• High-density quantum dot superlattice for application to high-efficiency solar cells　　　　　　　　　　　　　　　
  Ryuji Oshima; Yoshitaka Okada; Ayami Takata; Shuhei Yagi; Kouichi Akahane; Ryo Tamaki; Kenjiro Miyano
  PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 8, NO 2, 巻：8, 号：2, 2011年, ［査読有り］
  We characterized the optical absorption and solar cell characteristics of high-density InAs self-assembled quantum dots (QDs) grown on GaAs (001) substrates by atomic hydrogen-assisted molecular beam epitaxy. The GaNAs material can be used as strain-compensating layer (SCL) thereby minimizing the net strain, and thus is advantageous for multi-stacking of InAs QDs structures. As a result, dislocations and coalesced islands were not ob-served in 100 layer-stacked QDs. For QD solar cell characterization, the short-circuit current density of QDSC increases with increasing number of QD stacks, and reaches as high as 26.4 mA/cm(2) for 50 layer-stacked sample under air-mass 1.5 condition. However, the light absorption by QD superlattice as determined by optical absorption measurements at is limited to similar to 10% even for 100 layer-stacked samples. (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.201000461
  DOI ID：10.1002/pssc.201000461, ISSN：1862-6351, Web of Science ID：WOS:000301533800123
• 量子ドット超格子による高効率太陽電池の開発　　　　　　　　　　　　　　　
  岡田 至崇; 八木 修平; 大島 隆治
  應用物理, 巻：79, 号：3, 開始ページ：206, 終了ページ：212, 2010年03月, ［査読有り］
  応用物理学会, 日本語
  ISSN：0369-8009, J-Global ID：201002233272788305, CiNii Articles ID：10026199411, CiNii Books ID：AN00026679
• Evaluation of selective energy contact for hot carrier solar cells based on III-V semiconductors　　　　　　　　　　　　　　　
  Shuhei Yagi; Ryuji Oshima; Yoshitaka Okada
  Conference Record of the IEEE Photovoltaic Specialists Conference, 開始ページ：000530, 終了ページ：000533, 2009年, ［査読有り］
  We investigate hot carrier solar cells using III-V semiconductors. Here, the properties of a quantum well double barrier resonant tunneling structure comprised of Al0.6Ga0.4As/GaAs/Al0.6Ga 0.4As was used as selective energy contacts (SEC). The sample was fabricated by MBE on GaAs(001). The GaAs epitaxial layers were used as the optical absorbing layer. A quantum well resonant tunneling structure was adopted here for SEC because of its simplicity and maturity of fabrication technique. Preliminary evaluation was carried out by measuring current-voltage properties under light illumination in order to demonstrate hot carrier generation and collection through SEC. Photocurrent was measured at 77K and laser excitation was carried out with the emission wavelength of 643 nm and 805 nm which excite the electrons to the conduction band of absorbing layer at ∼360 meV and ∼10 meV above the band edge, respectively. As a result, a voltage shift toward lower bias voltage was observed in the tail region of tunneling current in photo-assisted current-voltage curve with higher energy excitation compared to that with lower energy excitation. A Monte Carlo simulation taking into account the electronphonon interaction supports the validity of the measured results. These results indicate generation of hot electrons in the absorbing layer and their extraction through the SEC. ©2009 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.2009.5411629
  DOI ID：10.1109/PVSC.2009.5411629, ISSN：0160-8371, SCOPUS ID：77951595758
• Global Tuning of Local Molecular Phenomena:  An Alternative Approach to Bionanoelectronics　　　　　　　　　　　　　　　
  A. Bandyopadhyay; K. Nittoh; Y. Wakayama; S. Yagi; K. Miki
  The Journal of Physical Cehmistry B, 巻：110, 号：42, 開始ページ：20852, 終了ページ：20857, 2006年09月
  英語, 研究論文（学術雑誌）
• Surface bismuth removal after Bi nanoline encapsulation in silicon
  Yagi, S.; Yashiro, W.; Sakamoto, K.; Miki, K.
  Surface Science, 巻：595, 号：1-3, 2005年
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1016/j.susc.2005.08.013
  DOI ID：10.1016/j.susc.2005.08.013, ISSN：0039-6028, ORCID：127971396, SCOPUS ID：27644522002
• Substitutional C incorporation into Si1-yCy alloys using novel carbon source, 1,3-disilabutane　　　　　　　　　　　　　　　
  S Yagi; K Abe; A Yamada; M Konagai
  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：43, 号：7A, 開始ページ：4153, 終了ページ：4154, 2004年07月, ［査読有り］
  A new carbon source, 1,3-disilabutane (H3Si-CH2-SiH2-CH3:1,3-DSB), is proposed for use in the growth of epitaxial Si1-yCy films with high C substitutionality. The Si1-yCy films have been deposited by plasma-enhanced chemical vapor deposition (PECVD). The Si1-yCy films grown using C2H2 or SiH2(CH3)(2) show a reduction in C substitutionality when total C content is more than 2%, whereas they show a marked improvement in C substitutionality for C contents up to 2.5% using 1,3-DSB as a C source.
  INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1143/JJAP.43.4153
  DOI ID：10.1143/JJAP.43.4153, ISSN：0021-4922, Web of Science ID：WOS:000223001800019
• C stability in Si1-yCy epitaxial films grown by low-temperature chemical vapor deposition　　　　　　　　　　　　　　　
  S Yagi; K Abe; A Yamada; M Konagai
  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：42, 号：4A, 開始ページ：1499, 終了ページ：1502, 2003年04月, ［査読有り］
  Thermal stability of the substitutional C (C-sub) in the Si1-yCy film has been investigated. The Si1-yCy films were grown on Si(001) substrates by low-temperature plasma-enhanced chemical vapor deposition using SiH4 and H-2. C2H2 or SiH2(CH3)(2) were used as C source gases. The simulation taking into account the chemical reactions of the complexes of the Si-C-H system in the S1-yCy well explained the annealing behavior and thermal stability of the Si1-yCy films. During high-temperature annealing, thermal diffusion of C-sub occurred resulting in 3C-SiC precipitation. The activation energy for the precipitation was estimated at 3.18-3.23 eV from the simulation. Both the calculated and experimental results showed that thermal stability of the Si1-yCy decreased with increasing initial C-sub content in the film.
  INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1143/jjap.42.1499
  DOI ID：10.1143/jjap.42.1499, ISSN：0021-4922, CiNii Articles ID：150000041156, Web of Science ID：WOS:000182892300001
• Phosphorous doping of strain-induced Si1-yCy epitaxial films grown by low-temperature chemical vapor deposition　　　　　　　　　　　　　　　
  S Yagi; K Abe; T Okabayashi; Y Yoneyama; A Yamada; M Konagai
  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：41, 号：4B, 開始ページ：2472, 終了ページ：2475, 2002年04月, ［査読有り］
  Pseudomorphic Si1-yCy alloy layers were grown on Si(001) substrates by plasma-enhanced chemical vapor deposition and mercury-sensitized photochemical vapor deposition. By depositing the films using SiH4, H-2 and SiH2(CH3)(2) at a derv low substrate temperature of 200degreesC, we successfully obtained epitaxial Si1-yCy films with a high substitutional C composition of up to 3.5%. In situ P doping was carried out using PH3, Si1-yCy films required annealing to activate the P atoms. However, the measured Hall mobility of the Si1-yCy films decreased after annealing at 700degreesC. After thermal treatment at 900degreesC for 1 min, the mobility recovered to the same level as that of bulk Si and an electron concentration of about 10(19) cm(-3) Was achieved.
  INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1143/JJAP.41.2472
  DOI ID：10.1143/JJAP.41.2472, ISSN：0021-4922, CiNii Articles ID：150000039821, Web of Science ID：WOS:000175703200038
• Growth and characterization of phosphorus doped Si1-yCy alloy grown by photo- and plasma-CVD at very low temperature　　　　　　　　　　　　　　　
  K Abe; S Yagi; T Okabayashi; A Yamada; M Konagai
  MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY, 巻：89, 号：1-3, 開始ページ：303, 終了ページ：305, 2002年02月, ［査読有り］
  The properties of Si1-yCy alloys grown on Si(001) by photo- and plasma-CVD are described. Epitaxial Si films were obtained by the addition of C2H2 CH4 or SiH2(CH3)(2) to SiH4 and H-2 gases at a substrate temperature of 200 degreesC by these two methods. Hydrogen incorporated in the epitaxial films during growth was observed to desorb on thermal annealing. The local vibration mode (607 cm(-1)) of C in Si was observed in the Raman spectra of films annealed at 700 degreesC. X-ray reciprocal lattice space mapping showed the Si1-yCy. alloys to be pseudomorphic. The highest substitutional C content of 3.5 at.% was obtained in the films grown with the addition of SiH2(CH3)(2). In-situ phosphorus doping was also carried out using PH3. The electron concentration of Si1-yCy films was lower than that of Si films grown at the same PH3/SiH4 ratio. However, the electron concentration was found to increase to the same level as Si films after annealing at 700 degreesC, to a magnitude of 5 x 10(18) cm(-3). This result implies that dopant neutralization occurred in the as-grown Si1-yCy films. (C) 2002 Published by Elsevier Science B.V.
  ELSEVIER SCIENCE SA, 英語, 研究論文（学術雑誌）
  ISSN：0921-5107, Web of Science ID：WOS:000174015300063
• Characterization of tensile strained Si1-yCy alloy grown by photo- and plasma chemical vapor deposition at very low temperature　　　　　　　　　　　　　　　
  K Abe; S Yagi; T Okabayashi; A Yamada; M Konagai
  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, 巻：40, 号：7, 開始ページ：4440, 終了ページ：4444, 2001年07月, ［査読有り］
  Epitaxial growth of Si1-vCv films on Si(001) by photochemical vapor deposition (photo-CVD) and plasma-enhanced chemical vapor deposition (plasma-CVD) is reported. We obtained the epitaxial Si films by the addition of C2H2 or CH4 to SiH4 and H-2 gases using both methods at a very low substrate temperature of 200 degreesC. Hydrogen incorporation in the epitaxial films and lattice expansion by H atoms were observed. The H atoms in the film desorbed by thermal annealing in N-2 atmosphere. The C local vibration mode in the Si network (607 cm(-1)) was detected in the films annealed at temperatures higher than 600 degreesC. X-ray diffraction peak of the Si1-yCy layer shifted to a higher angle by the annealing. The X-ray reciprocal lattice space mapping indicated pseudomorphic growth of Si1-yCy alloys. Thus, the tensile strained Si1-yCy alloy with a high substitutional C content of 2.7% was successfully obtained.
  INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1143/JJAP.40.4440
  DOI ID：10.1143/JJAP.40.4440, ISSN：0021-4922, CiNii Articles ID：10006237194, Web of Science ID：WOS:000170772500002
• Epitaxial growth of Si1-yCy film by low temperature chemical vapor deposition　　　　　　　　　　　　　　　
  S Yagi; K Abe; A Yamada; M Konagai
  JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS, 巻：39, 号：11A, 開始ページ：L1078, 終了ページ：L1080, 2000年11月, ［査読有り］
  Epitaxial Si1-yCy films were grown on Si(100) by two methods, mercury sensitized photochemical vapor deposition and plasma-enhanced chemical vapor deposition, at substrate temperatures of around 200 degreesC using SiH4, H-2 and C2H2. The vibration mode at 607 cm(-1), which indicated the presence of the C atoms located at the Si substitutional sites, was observed in both Fourier transform infrared absorption and Raman scattering spectroscopy of the samples annealed at 600 to 700 degreesC. The C composition was controlled by varying the C2H2/SiH4 ratio. The maximum substitutional C compositions of 2.3 at% and 2.7 at% were successfully obtained by mercury sensitized photochemical vapor deposition and plasma-enhanced chemical vapor deposition, respectively.
  INST PURE APPLIED PHYSICS, 英語, 研究論文（学術雑誌）
  ISSN：0021-4922, Web of Science ID：WOS:000167218300002

• 窒素δドープGaAs中の等電子トラップに局在した励起子分子の束縛エネルギーに関する研究　　　　　　　　　　　　　　　
  矢野裕子; 高宮健吾; 藤川沙千恵; 八木修平; 矢口裕之; 小林真隆; 秋山英文
  応用物理学会春季学術講演会講演予稿集(CD-ROM), 巻：70th, 2023年
  ISSN：2436-7613, J-Global ID：202302286333664872
• 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
  応用物理学会春季学術講演会講演予稿集(CD-ROM), 巻：69th, 2022年
  ISSN：2436-7613, J-Global ID：202202243673645430
• 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
  応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：79th, 開始ページ：ROMBUNNO.18p‐234B‐6, 2018年09月05日
  日本語
  J-Global ID：201802221348887183
• 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
  応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：79th, 開始ページ：ROMBUNNO.18p‐234B‐4, 2018年09月05日
  日本語
  J-Global ID：201802238518840151
• 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
  応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：79th, 開始ページ：ROMBUNNO.19p‐PA4‐25, 2018年09月05日
  日本語
  J-Global ID：201802262792771299
• 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
  応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：79th, 開始ページ：ROMBUNNO.19p‐PA4‐14, 2018年09月
  日本語
  J-Global ID：201802290158483556
• 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
  応用物理学会春季学術講演会講演予稿集(CD-ROM), 巻：65th, 開始ページ：ROMBUNNO.18p‐P8‐12, 2018年03月05日
  日本語
  J-Global ID：201802217506237741
• Growth of InGaAs:Nδ-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
  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.
  英語
  ISSN：2159-2330, eISSN：2159-2349, Web of Science ID：WOS:000469200401194
• 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), 巻：78th, 開始ページ：ROMBUNNO.6p‐PA7‐1, 2017年08月25日
  日本語
  J-Global ID：201702255331459722
• 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), 巻：78th, 開始ページ：ROMBUNNO.5p‐PA3‐7, 2017年08月25日
  日本語
  J-Global ID：201702271908434102
• 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
  応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：78th, 開始ページ：ROMBUNNO.5p‐C21‐1, 2017年08月25日
  日本語
  J-Global ID：201702278507065273
• 基板再利用に向けたELO後基板の清浄化工程と再成長の検討
  宮下直也; 八木修平; 渡辺健太郎; 木村大希; SODABANLU Hassanet; 中田達也; 杉山正和; 杉山正和; 岡田至崇
  応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：78th, 開始ページ：ROMBUNNO.6p‐PA5‐23, 2017年08月
  日本語
  J-Global ID：201702288830548138
• 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), 巻：64th, 開始ページ：ROMBUNNO.17p‐P2‐8, 2017年03月01日
  日本語
  J-Global ID：201702218011102092
• 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), 巻：64th, 開始ページ：ROMBUNNO.14p‐B6‐9, 2017年03月01日
  日本語
  J-Global ID：201702242750399704
• 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), 巻：64th, 開始ページ：ROMBUNNO.15p‐P16‐8, 2017年03月01日
  日本語
  J-Global ID：201702266277509859
• 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), 巻：64th, 開始ページ：ROMBUNNO.16p‐F201‐3, 2017年03月01日
  日本語
  ISSN：2436-7613, J-Global ID：201702283758456263
• 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), 巻：77th, 開始ページ：ROMBUNNO.16a‐P5‐11, 2016年09月01日
  日本語
  J-Global ID：201602236541953232
• 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), 巻：77th, 開始ページ：ROMBUNNO.15a‐P11‐11, 2016年09月01日
  日本語
  J-Global ID：201602248642339078
• 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), 巻：77th, 開始ページ：ROMBUNNO.13p‐P9‐11, 2016年09月01日
  日本語
  ISSN：2436-7613, J-Global ID：201602279619229573
• 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), 巻：63rd, 開始ページ：ROMBUNNO.19P-W242-6, 2016年03月03日
  日本語
  ISSN：2436-7613, J-Global ID：201602206159061072
• 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), 巻：63rd, 開始ページ：ROMBUNNO.22A-P6-10, 2016年03月03日
  日本語
  J-Global ID：201602218989088990
• 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), 巻：63rd, 開始ページ：ROMBUNNO.20A-H101-9, 2016年03月03日
  日本語
  J-Global ID：201602220555984119
• Self-Organized Growth of Cubic InN Dot Arrays on MgO (001) Vicinal Substrates　　　　　　　　　　　　　　　
  Kenichi Ishii; Shuhei Yagi; Hiroyuki Yaguchi
  2016年, ［査読有り］
  英語
  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年, ［査読有り］
  英語
  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年, ［査読有り］
  英語
  Web of Science ID：WOS:000392285400077
• 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), 巻：76th, 開始ページ：ROMBUNNO.13P-PB2-5, 2015年08月31日
  日本語
  J-Global ID：201502200169002575
• 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), 巻：76th, 開始ページ：ROMBUNNO.15A-1A-11, 2015年08月31日
  日本語
  J-Global ID：201502200868414404
• 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), 巻：76th, 開始ページ：ROMBUNNO.13P-PB2-2, 2015年08月31日
  日本語
  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
  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), 巻：76th, 開始ページ：ROMBUNNO.14P-PB12-19, 2015年08月31日
  日本語
  J-Global ID：201502207396200760
• 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), 巻：76th, 開始ページ：ROMBUNNO.13P-PB2-1, 2015年08月31日
  日本語
  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
  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), 巻：76th, 開始ページ：ROMBUNNO.13P-PB2-3, 2015年08月31日
  日本語
  J-Global ID：201502215233126671
• 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), 巻：76th, 開始ページ：ROMBUNNO.13P-PB2-4, 2015年08月31日
  日本語
  J-Global ID：201502221370971885
• 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), 巻：62nd, 開始ページ：ROMBUNNO.13P-P19-17, 2015年02月26日
  日本語
  J-Global ID：201502212728546006
• 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), 巻：62nd, 開始ページ：ROMBUNNO.12P-P16-9, 2015年02月26日
  日本語
  J-Global ID：201502237562705111
• 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), 巻：62nd, 開始ページ：ROMBUNNO.13A-P15-2, 2015年02月26日
  日本語
  J-Global ID：201502238490747422
• 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), 巻：75th, 開始ページ：ROMBUNNO.19P-PB3-10, 2014年09月01日
  日本語
  J-Global ID：201402204873316264
• 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), 巻：75th, 開始ページ：ROMBUNNO.19A-PB5-11, 2014年09月01日
  日本語
  J-Global ID：201402218643252926
• 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), 巻：75th, 開始ページ：ROMBUNNO.19A-S1-6, 2014年09月01日
  日本語
  J-Global ID：201402223396439019
• 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), 巻：61st, 開始ページ：ROMBUNNO.20A-PG1-15, 2014年03月03日
  日本語
  J-Global ID：201402228659986330
• 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), 巻：47th, 開始ページ：ROMBUNNO.10-3, 2014年
  日本語
  J-Global ID：201402295481095788
• 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), 巻：74th, 開始ページ：ROMBUNNO.19A-P9-4, 2013年08月31日
  日本語
  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
  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.19A-P8-11, 2013年08月31日
  日本語
  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
  岩崎卓也; 八木修平; 土方泰斗; 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), 巻：74th, 開始ページ：ROMBUNNO.19A-P8-13, 2013年08月31日
  日本語
  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
  山崎泰由; 八木修平; 土方泰斗; 尾鍋研太郎; 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, 開始ページ：ROMBUNNO.19A-P8-14, 2013年08月31日
  日本語
  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
  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.17P-D6-14, 2013年08月31日
  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, 開始ページ：ROMBUNNO.17P-P7-15, 2013年08月31日
  日本語
  J-Global ID：201302285385764625
• 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
• 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―
  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, 巻：113, 号：87(SDM2013 44-64), 開始ページ：91, 終了ページ：96, 2013年06月11日
  日本語
  ISSN：0913-5685, J-Global ID：201302213724044520
• 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
• ホットキャリアを利用した新型太陽電池の開発
  八木修平; 岡田至崇
  ゼネラル石油研究奨励財団研究報告書, 号：15, 開始ページ：8, 終了ページ：11, 2013年02月01日
  日本語
  J-Global ID：201402263729291920
• Optical absorption by E+ miniband of GaAs:N δ-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
  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.
  英語
  ISSN：0160-8371, Web of Science ID：WOS:000340054100565
• 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
• 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
• Analysis of the energy structure of nitrogen δ-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, 開始ページ：83, 終了ページ：86, 2012年
  Nitrogen δ-doped GaAs superlattices were fabricated and their energy structures were investigated. Several transitions related to E+ band of nitrogen δ-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 δ-doped GaAs superlattice structures are expected to be an excellent alternative for the use of intermediate band solar cells. © 2012 IEEE.
  英語
  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, SCOPUS ID：84869429937
• RF‐MBE法によるInN(10‐13)及びInGaN(10‐13)のGaAs(110)基板上への成長
  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：72nd, 開始ページ：ROMBUNNO.30A-ZE-8, 2011年08月16日
  日本語
  J-Global ID：201102239405788481
• 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
• Quantum well double barrier resonant tunneling structures for selective contacts of hot carrier solar cells　　　　　　　　　　　　　　　
  Shuhei Yagi; Yasuto Hijikata; Yoshitaka Okada; Hiroyuki Yaguchi
  開始ページ：003309, 終了ページ：003312, 2011年
  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.
  DOI：https://doi.org/10.1109/PVSC.2011.6186646
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84861083769&origin=inward
  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, SCOPUS ID：84861083769
• 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
• 高密度InAs/GaNAs量子ドット太陽電池構造の光学特性評価
  大島隆治; 高田彩未; 八木修平; 赤羽浩一; 玉置亮; 宮野健次郎; 岡田至崇
  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.16A-ZV-3, 2010年08月30日
  日本語
  J-Global ID：201002240598104615
• Fabrication of resonant tunneling structures for selective energy contact of hot carrier solar cell based on III–V semiconductors　　　　　　　　　　　　　　　
  Shuhei Yagi; Yoshitaka Okada
  2010 35th IEEE Photovoltaic Specialists Conference, 開始ページ：1213, 終了ページ：1216, 2010年
  In this study, double barrier (DB) resonant tunneling structures based on III-V semiconductors were fabricated and its potential for selective energy contacts (SEC) of hot carrier solar cells was evaluated. An AlGaAs/GaAs/AlGaAs quantum well (QW) based DB structure was fabricated by molecular beam epitaxy (MBE) on GaAs (001) substrate, which acts as SEC for electrons. The current-voltage (I-V) characteristics under light excitation shows a voltage shift of tunneling current tail to a lower bias and this result demonstrates an extraction of high energy photoelectrons through the DB structure. Furthermore, properties of quantum dot (QD) resonant tunneling structures were investigated as an ideal SEC. Photoluminescence (PL) measurements showed that controllable PL peak energy range of InAs QDs/AlxGa1-xAs structures well corresponds to the required carrier extraction energy, which is the difference between electron and hole extraction energies of SECs, for high conversion efficiency. In addition, resonant tunneling current peaks originate from the InAs QDs embedded in an Al0.6Ga0.4As barrier are clearly observed for both forward and reverse bias by conductive atomic force microscope (C-AFM). These results indicate that InAs QD/AlxGa1-xAs resonant tunneling structures are suitable for designing the optimum SEC structure.
  英語
  DOI：https://doi.org/10.1109/PVSC.2010.5614058
  DOI ID：10.1109/PVSC.2010.5614058, ISSN：0160-8371, Web of Science ID：WOS:000287579501092
• ホットキャリア太陽電池に向けたエネルギー選択層の評価(II)
  八木修平; 大島隆治; 岡田至崇
  応用物理学会学術講演会講演予稿集, 巻：70th, 号：3, 開始ページ：1308, 2009年09月08日
  日本語
  J-Global ID：200902295067574313
• ホットキャリア太陽電池に向けたエネルギー選択層(SEC)の評価
  八木修平; 大島隆治; 岡田至崇
  応用物理学関係連合講演会講演予稿集, 巻：56th, 号：3, 開始ページ：1453, 2009年03月30日
  日本語
  J-Global ID：200902253305069261
• Evaluation of selective energy contact for hot carrier solar cells based on III–V semiconductors　　　　　　　　　　　　　　　
  Shuhei Yagi; Ryuji Oshima; Yoshitaka Okada
  2009 34th IEEE Photovoltaic Specialists Conference (PVSC), 開始ページ：1322, 終了ページ：1325, 2009年
  We investigate hot carrier solar cells using HI-V semiconductors. Here, the properties of a quantum well double barrier resonant tunneling structure comprised of Al(0.6)Ga(0.4)As/GaAs/Al(0.6)Ga(0.4)As was used as selective energy contacts (SEC). The sample was fabricated by MBE on GaAs(001). The GaAs epitaxial layers were used as the optical absorbing layer. A quantum well resonant tunneling structure was adopted here for SEC because of its simplicity and maturity of fabrication technique. Preliminary evaluation was carried out by measuring current-voltage properties under light illumination in order to demonstrate hot carrier generation and collection through SEC. Photocurrent was measured at 77K and laser excitation was carried out with the emission wavelength of 643 nm and 805 nm which excite the electrons to the conduction band of absorbing layer at similar to 360 meV and similar to 10 meV above the band edge, respectively. As a result, a voltage shift toward lower bias voltage was observed in the tail region of tunneling current in photo-assisted current-voltage curve with higher energy excitation compared to that with lower energy excitation. A Monte Carlo simulation taking into account the electron-phonon interaction supports the validity of the measured results. These results indicate generation of hot electrons in the absorbing layer and their extraction through the SEC.
  英語
  ISSN：0160-8371, Web of Science ID：WOS:000280345900288
• InGaAs/GaAs系超格子構造太陽電池におけるキャリアの脱出過程
  八木修平; 永持創一朗; 大島隆治; 岡田至崇
  応用物理学関係連合講演会講演予稿集, 巻：55th, 号：1, 開始ページ：369, 2008年03月27日
  日本語
  J-Global ID：200902231653046000
• シリコン結晶中へのδドーピング III:電気特性
  八木修平; 坂本邦博; 三木一司
  応用物理学会学術講演会講演予稿集, 巻：67th, 号：1, 開始ページ：361, 2006年08月29日
  日本語
  J-Global ID：200902263589291134
• シリコン結晶中へのδドーピング I:ビスマス原子細線を利用した手法
  三木一司; 八木修平; 坂本邦博; 深津晋
  応用物理学関係連合講演会講演予稿集, 巻：53rd, 号：1, 開始ページ：405, 2006年03月22日
  日本語
  J-Global ID：200902225954321952
• シリコン結晶中へのδドーピング II:ビスマスとエルビウムの共ドーピング
  八木修平; 安原望; 坂本邦博; 深津晋; 三木一司
  応用物理学関係連合講演会講演予稿集, 巻：53rd, 号：1, 開始ページ：405, 2006年03月22日
  日本語
  J-Global ID：200902243706251024
• 光学マルチセルを使った画像処理用2次元分子コンピュータの試作
  日塔光一; 八木修平; 大橋勝文; 三木一司
  応用物理学関係連合講演会講演予稿集, 巻：53rd, 号：3, 開始ページ：1352, 2006年03月22日
  日本語
  J-Global ID：200902257906680133
• 埋め込み型ビスマス原子細線 4:電気伝導測定
  日塔光一; 八木修平; 矢代航; 白木一郎; 坂本邦博; 三木一司
  応用物理学関係連合講演会講演予稿集, 巻：52nd, 号：2, 開始ページ：755, 2005年03月29日
  日本語
  J-Global ID：200902236484514645
• 埋め込み型Bi原子細線 1:加熱による消滅
  八木修平; 矢代航; 坂本邦博; 三木一司
  応用物理学関係連合講演会講演予稿集, 巻：52nd, 号：2, 開始ページ：754, 2005年03月29日
  日本語
  J-Global ID：200902297810926141
• ガスソースMBE法により作製したSi_1-yC_y混晶薄膜の熱的安定性
  阿部克也; 矢部千晶; 八木修平; 綿引達郎; 山田明; 小長井誠
  応用物理学関係連合講演会講演予稿集, 巻：50th, 号：1, 開始ページ：463, 2003年03月27日
  日本語
  J-Global ID：200902229600851658
• Theoretical and Experimental Analyses of C stability in Epitaxial Si_1-y_C_y_ Films　　　　　　　　　　　　　　　
  S. Yagi; K. Abe; A; Yamada; M. Konagai
  開始ページ：62, 終了ページ：64, 2003年
• Novel Carbon Source (1,3-Disilabutane) for the Deposition of Microcrystalline Silicon Carbon　　　　　　　　　　　　　　　
  Shuhei Yagi; Takashi Okabayashi; Katsuya Abe Akira Yamada; Makoto Konagai
  開始ページ：101, 2003年
• 1,3‐ジシラブタンを用いたSi_1-yC_y薄膜の低温エピタキシャル成長
  八木修平; 阿部克也; 山田明; 小長井誠
  応用物理学会学術講演会講演予稿集, 巻：63rd, 号：1, 開始ページ：372, 2002年09月24日
  日本語
  J-Global ID：200902114548381468
• 1,3‐ジシラブタンをCソースに用いた微結晶Si_1-xC_x薄膜の作製
  岡林尚志; 八木修平; 阿部克也; 山田明; 小長井誠
  応用物理学会学術講演会講演予稿集, 巻：63rd, 号：2, 開始ページ：833, 2002年09月24日
  日本語
  J-Global ID：200902176453380338
• 1,3‐ジシラブタンをCソースに用いた光CVD法によるa‐SiC薄膜の作製
  岡林尚志; 八木修平; 阿部克也; 山田明; 小長井誠
  応用物理学関係連合講演会講演予稿集, 巻：49th, 号：2, 開始ページ：920, 2002年03月27日
  日本語
  J-Global ID：200902102616909370
• IV族混晶半導体Si_1-yC_yにおけるCの熱的安定性
  八木修平; 阿部克也; 岡林尚志; 米山雄一; 山田明; 小長井誠
  応用物理学関係連合講演会講演予稿集, 巻：49th, 号：1, 開始ページ：412, 2002年03月27日
  日本語
  J-Global ID：200902126295642225
• Novel carbon source (1,3-disilabutane) for the deposition of p-type a-SiC　　　　　　　　　　　　　　　
  S Yagi; T Okkabayashi; K Abe; A Yamada; M Konagai
  巻：715, 開始ページ：533, 終了ページ：537, 2002年
  We proposed a new carbon source, 1,3-disilabutane (H3Si-CH2-SiH2-CH3:l,3-DSB), to grow hydrogenated amorphous silicon carbide (a-SiC:H) films by mercury-sensitized photochemical vapor deposition (photo-CVD). We described preliminary results of undoped and p-type a-SiC films deposited using 1,3-DSB. It was found that the optical energy gap of the films was changed even at very small 1,3-DSB/silane ratios of few percents. P-type doping was carried out by using diborane and we obtained the films with a darkconductivity of 1.3x10(-4) S/cm at the optical bandgap of 2.1 eV In addition, we applied this material for a p-layer of a p-i-n type a-Si based solar cell and we have achieved relatively high conversion efficiency of 9.55%.
  英語
  ISSN：0272-9172, Web of Science ID：WOS:000179162400076
• P-Doping into Strain-Induced Si_<1-y>C_y Epitaxial Films Grown by Low Temperature Chemical Vapor Deposition　　　　　　　　　　　　　　　
  YAGI Shuhei; ABE Katsuya; OKABAYASHI Takashi; YAMADA Akira; KONAGAI Makoto
  Extended abstracts of the ... Conference on Solid State Devices and Materials, 巻：2001, 開始ページ：484, 終了ページ：485, 2001年09月25日
  英語
  CiNii Articles ID：10015753496, CiNii Books ID：AA10777858
• プラズマCVD法によるSi_1-yC_y薄導へのPドーピング
  八木修平; 阿部克也; 岡林尚志; 山田明; 小長井誠
  応用物理学関係連合講演会講演予稿集, 巻：48th, 号：1, 開始ページ：460, 2001年03月28日
  日本語
  J-Global ID：201202168097926110
• SiH₂(CH₃)₂を用いたSi_1-yC_y薄膜の家温エピタキシャル成長
  八木修平; 阿部克也; 岡林尚志; 山田明; 小長井誠
  応用物理学会学術講演会講演予稿集, 巻：61st, 号：1, 開始ページ：336, 2000年09月03日
  日本語
  J-Global ID：201202147608902773
• 非平衡CVD法により作製したSi_1-yC_y膜の構造評価
  阿部克也; 八木修平; 岡林尚志; 山田明; 小長井誠
  応用物理学会学術講演会講演予稿集, 巻：61st, 号：1, 開始ページ：336, 2000年09月03日
  日本語
  J-Global ID：201202174940855751
• 低温形成Siエピタキシャル薄膜へのC添加の試み
  八木修平; 阿部克也; 山田明; 小長井誠
  応用物理学関係連合講演会講演予稿集, 巻：47th, 号：1, 開始ページ：409, 2000年03月28日
  日本語
  J-Global ID：201202179484876018
• MBE成長におけるIn表面偏析効果のモンテカルロシミュレーション
  安田佳克; 八木修平; 山口浩一
  応用物理学会学術講演会講演予稿集, 巻：60th, 号：3, 開始ページ：1113, 1999年09月01日
  日本語
  J-Global ID：200902128553405317

• 超高効率太陽電池・関連材料の最前線（荒川康彦 監修）　　　　　　　　　　　　　　　
  八木 修平, ［分担執筆］, 第5章3節

• 2020年10月 - 現在
  電気回路, 埼玉大学
• 2020年04月 - 2021年09月
  理工学と現代社会, 埼玉大学
• 基礎電気回路・演習, 埼玉大学
• 電気電子システム実験III, 埼玉大学
• 電気電子システム実験II, 埼玉大学
• 半導体工学特論, 埼玉大学大学院
• 電気電子材料工学, 埼玉大学
• 電気電子物理工学輪講, 埼玉大学大学院
• 応用半導体工学特論, 埼玉大学大学院

• 2020年10月 - 現在, 日本太陽光発電学会
• 電子情報通信学会
• 応用物理学会

• 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
• 中間バンド型太陽電池の高効率化に向けた積層セル構造の提案　　　　　　　　　　　　　　　
  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), 2022年04月01日 - 2025年03月31日
  八木 修平, 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
  課題番号：22K04211
  論文ID：42822455
• 希釈窒化物混晶による超高効率中間バンドタンデム太陽電池の研究　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業 国際共同研究加速基金(国際共同研究強化), 2018年04月 - 2020年03月
  八木 修平, 研究代表者
  競争的資金
• 希釈窒化物半導体による高効率マルチバンド太陽電池の研究　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業 若手研究(A), 2016年04月 - 2019年03月
  八木 修平, 研究代表者
  競争的資金
• 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), 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。
  課題番号：26390057
• 窒化物半導体ナノ構造中のホットキャリアを利用する新型太陽電池に関する研究　　　　　　　　　　　　　　　
  独立行政法人科学技術振興機構, 研究成果最適展開支援プログラム(A-STEP) 探索タイプ, 2014年12月 - 2015年11月
  八木 修平, 研究代表者
  競争的資金
• 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), 2012年04月 - 2015年03月
  矢口 裕之
  競争的資金
• 窒化物量子ドット太陽電池の開発　　　　　　　　　　　　　　　
  独立行政法人科学技術振興機構, 研究成果最適展開支援プログラム（A-STEP） 探索タイプ, 2012年11月 - 2013年10月
  八木 修平, 研究代表者
  競争的資金
• 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), 2009年04月 - 2011年03月
  矢口 裕之
  競争的資金
• ‐　　　　　　　　　　　　　　　
  競争的資金
• -　　　　　　　　　　　　　　　
  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
• 光検出素子及び光検出方法　　　　　　　　　　　　　　　
  佐藤 大典; 岡田 至崇; 八木 修平, 特許権
  J-Global ID：201303058776438657
• 可逆光応答素子を用いた並列アナログ演算装置　　　　　　　　　　　　　　　
  大橋 勝文; 三木 一司; 八木 修平; 日塔 光一, 特許権
  特許番号・登録番号：特許第5236173号
  J-Global ID：201303078366538698
• 半導体とその製造方法　　　　　　　　　　　　　　　
  三木 一司; 八木 修平; 日塔 光一; 坂本 邦博, 特許権
  特許番号・登録番号：特許第5187761号
  J-Global ID：201303069665849951
• 光透過フィルタを用いた画像出力装置及び並列アナログ演算装置　　　　　　　　　　　　　　　
  三木 一司; 大橋 勝文; 八木 修平; 日塔 光一, 特許権
  特許番号・登録番号：特許第5121198号
  J-Global ID：201303003170113079
• 可逆光応答素子並びにそれを用いた撮像装置及び並列アナログ演算装置　　　　　　　　　　　　　　　
  大橋 勝文; 三木 一司; 八木 修平; 日塔 光一, 特許権
  J-Global ID：200903049895238508
• 光透過フィルタ並びにそれを用いた画像出力装置及び並列アナログ演算装置　　　　　　　　　　　　　　　
  三木 一司; 大橋 勝文; 八木 修平; 日塔 光一, 特許権
  J-Global ID：200903083194405497
• 半導体とその製造方法　　　　　　　　　　　　　　　
  三木 一司; 八木 修平; 日塔 光一; 坂本 邦博, 特許権
  J-Global ID：201003020026758820