Performance information

• Demonstration of Quantum Polarization Microscopy using an Entangled-Photon Source
  Yasuto Hijikata
  ArXiv, Jan. 2025
  Scientific journal
  DOI：https://doi.org/10.3390/photonics12020127
  DOI ID：10.3390/photonics12020127, ORCID：179943162
• Characterization of Amorphous SnO₂:N Thin-films Prepared by RF Magnetron Sputtering in Ar/N₂ Mixed Gas Atmosphere
  Takuma Kawaguchi; Ryuji Oishi; Maki Shimizu; Yasuto Hijikata; Shinya Aikawa
  IEEJ Transactions on Electronics, Information and Systems, Volume：144, Number：11, First page：1093, Last page：1099, Nov. 2024, [Reviewed]
  Institute of Electrical Engineers of Japan (IEE Japan), Japanese, Scientific journal
  DOI：https://doi.org/10.1541/ieejeiss.144.1093
  DOI ID：10.1541/ieejeiss.144.1093, ISSN：0385-4221, eISSN：1348-8155
• Thermoelectric measurements of nanomaterials by nanodiamond quantum thermometry　　　　　　　　　　　　　　　
  Maki Shimizu; Koki Sugimoto; Yasuto Hijikata
  Applied Physics Express, Sep. 2024
  Scientific journal
  DOI：https://doi.org/10.35848/1882-0786/ad6fe9
  DOI ID：10.35848/1882-0786/ad6fe9, ORCID：165592223
• The Influence of Oxygen‐Related Defects on the Formation of In2O3‐Based Low‐Fluorescence Transparent Conducting Film　　　　　　　　　　　　　　　
  Maki Shimizu; Masataka Shugo; Shun Mori; Yasuto Hijikata; Shinya Aikawa
  physica status solidi (a), Jun. 2023
  Scientific journal
  DOI：https://doi.org/10.1002/pssa.202200896
  DOI ID：10.1002/pssa.202200896, ORCID：134830830
• Optically detected magnetic resonance of silicon vacancies in 4H-SiC at elevated temperatures toward magnetic sensing under harsh environments
  Shu Motoki; Shin-ichiro Sato; Seiichi Saiki; Yuta Masuyama; Yuichi Yamazaki; Takeshi Ohshima; Koichi Murata; Hidekazu Tsuchida; Yasuto Hijikata
  Journal of Applied Physics, Volume：133, Number：15, Apr. 2023
  Scientific journal
  DOI：https://doi.org/10.1063/5.0139801
  DOI ID：10.1063/5.0139801, ISSN：1089-7550, ORCID：133244244, SCOPUS ID：85153679126
• Spin property improvement of boron vacancy defect in hexagonal boron nitride by thermal treatment
  Tetta Suzuki; Yuichi Yamazaki; Takashi Taniguchi; Kenji Watanabe; Yusuke Nishiya; Yu-ichiro Matsushita; Kazuya Harii; Yuta Masuyama; Yasuto Hijikata; Takeshi Ohshima
  Applied Physics Express, Volume：16, Number：3, First page：032006, Last page：032006, Mar. 2023, [Reviewed]
  Abstract
  
  Negatively charged boron vacancy (V _B ^–) in hexagonal boron nitride has attracted attention as a promising spin defect for quantum sensing applications. Hence, a fabrication method for generation of V _B ^– with superior spin properties would be desirable. In this study, we demonstrated V _B ^– formation by two thermal treatment methods. Both methods improve the signal-to-noise ratio of optically detected magnetic resonance signal by a factor of 4. Furthermore, a zero-field splitting parameter E which reflects crystal distortion after irradiation significantly reduces for irradiation above 650 °C. These findings indicate that thermal treatment is an effective method for a V _B ^– based quantum sensor.
  IOP Publishing, Scientific journal
  DOI：https://doi.org/10.35848/1882-0786/acc442
  DOI ID：10.35848/1882-0786/acc442, ISSN：1882-0778, eISSN：1882-0786
• Impact of formation process on the radiation properties of single-photon sources generated on SiC crystal surfaces　　　　　　　　　　　　　　　
  Yasuto Hijikata; Shota Komori; Shunsuke Otojima; Yu-Ichiro Matsushita; Takeshi Ohshima
  Applied Physics Letters, Volume：118, Number：20, May 2021
  Radiation centers that are generated on the surface of SiC crystals [surface single-photon sources (SPSs)] have received much attention because they behave as high-brightness SPSs at room temperature. However, little is known about surface SPSs, such as their defect structure and radiation properties. To achieve a better understanding of surface SPSs, we investigated the impact of the formation processes of SPSs on the radiation properties. Low temperature photoluminescence (PL) measurements indicated that the photon energies of the zero-phonon line (ZPL) were dispersed in the range of 0.33 eV. In comparison between the (0001) Si-face and (11-20) a-face, the energy dispersion for the a-face was smaller, which suggests that the energy dispersion was attributed to stacking faults at the oxide-SiC interface. The differences in the radiation properties of the surface SPSs were clarified according to the formation process in terms of the oxide thickness and post-oxidation Ar annealing. The results showed that the wavelength dispersion was increased with the oxide thickness, and Ar annealing caused various changes in the radiation properties, such as a reduction in the density of SPSs, and the radiation intensity of the ZPL as well as a shift in the ZPL wavelength. Notably, most of the changes in the defect structure occurred at the Ar anneal temperature of 600 °C, and we discuss some of the types of defects that change at this temperature.
  American Institute of Physics Inc., English, Scientific journal
  DOI：https://doi.org/10.1063/5.0048772
  DOI ID：10.1063/5.0048772, ISSN：0003-6951, SCOPUS ID：85106570372
• Influences of hydrogen ion irradiation on NcVsi− formation in 4H-silicon carbide　　　　　　　　　　　　　　　
  Takuma Narahara; Shin-Ichiro Sato; Kazutoshi Kojima; Yasuto Hijikata; Takeshi Ohshima
  Applied Physics Express, Volume：14, Number：2, Feb. 2021
  Nitrogen-vacancy (NCVSi−) center in 4H-SiC is spin defect with near-infrared luminescence at room temperature and a promising candidate for quantum technologies. This paper reports on NCVSi− center formation in N-doped 4H-SiCs by hydrogen ion irradiation and subsequent thermal annealing. It is revealed photoluminescence for NCVSi− centers suddenly appears above the fluence of 5.0 × 1015 cm−2 when annealed at 1000 °C. Appearance of a threshold fluence for their formation and/or activation has not been observed for other energetic particle irradiations. The possible mechanism is discussed based on the kinetics of hydrogen-related complexes and the majority carrier depletion caused by irradiation induced damage.
  IOP Publishing Ltd, English, Scientific journal
  DOI：https://doi.org/10.35848/1882-0786/abdc9e
  DOI ID：10.35848/1882-0786/abdc9e, ISSN：1882-0786, SCOPUS ID：85100388082
• Carrier dynamics of silicon vacancies of SiC under simultaneous optically and electrically excitations　　　　　　　　　　　　　　　
  Yuichi Yamazaki; Yoji Chiba; Shin-Ichiro Sato; Takahiro Makino; Naoto Yamada; Takahiro Satoh; Kazutoshi Kojima; Yasuto Hijikata; Hidekazu Tsuchida; Norihiro Hoshino; Sang-Yun Lee; Takeshi Ohshima
  Applied Physics Letters, Volume：118, Number：2, Jan. 2021
  Silicon carbide (SiC) is an important wide bandgap semiconductor used for diverse applications from heat spreading to high-power electronics. It is readily doped, has high thermal conductivity, and is used for application in mature device fabrication techniques. To improve the performance of SiC electronic devices, built-in sensors, which should ideally be inexpensive integrated with the device, and not perturb device operations, are quite useful. Here, we studied the optical properties of the negatively silicon vacancy under simultaneous optical and electrical excitation to uncover the carrier dynamics, as the luminescence intensity is determined by competition between the two excitation pathways. We also observe optically detected magnetic resonance (ODMR) and observe that the ODMR contrast is decreased by injected current, which is consistent with the decrease in the pumping rate of optical excitation in the competitive process. Our studies show that an embedded quantum sensor is possible in practical SiC devices, opening new opportunities for device control and optimization.
  American Institute of Physics Inc., English, Scientific journal
  DOI：https://doi.org/10.1063/5.0028318
  DOI ID：10.1063/5.0028318, ISSN：0003-6951, SCOPUS ID：85099354563
• Influence of neutron radiation on majority and minority carrier traps in n-type 4H-SiC　　　　　　　　　　　　　　　
  Ivana Capan; Tomislav Brodar; Yuichi Yamazaki; Yuya Oki; Takeshi Ohshima; Yoji Chiba; Yasuto Hijikata; Luka Snoj; Vladimir Radulović
  Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms, Volume：478, First page：224, Last page：228, Sep. 2020
  We report on influence of neutron radiation on majority and minority carrier traps in n-type 4H-SiC. Together with the increase of the well-known carbon vacancy (VC) majority carrier related trap, neutron irradiation has introduced two deep traps, labeled as EH1 and EH3 with the activation energies for electron emission estimated as 0.4 and 0.7 eV bellow the conduction band, respectively. Based on Laplace deep level transient spectroscopy (DLTS) results, we have assigned EH1 trap to silicon vacancy (VSi). Two minority carrier traps labelled as B and D-center were detected by minority transient spectroscopy (MCTS) and assigned to substitutional boron BSi and BC, respectively. Activation energies for hole emission for B and D-center are estimated as 0.27 and 0.60 eV above the valence band, respectively. We have identified two emission lines for D-center by Laplace-MCTS measurements and assigned them to BC sitting at hexagonal (−h) and cubic (−k) lattice sites.
  Elsevier B.V., English, Scientific journal
  DOI：https://doi.org/10.1016/j.nimb.2020.07.005
  DOI ID：10.1016/j.nimb.2020.07.005, ISSN：0168-583X, SCOPUS ID：85088126382
• Near infrared photoluminescence of ncvsi-centers in high-purity semi-insulating 4h-sic irradiated with energetic charged particles　　　　　　　　　　　　　　　
  Shin-Ichiro Sato; Takuma Narahara; Shinobu Onoda; Yuichi Yamazaki; Yasuto Hijikata; Brant C. Gibson; Andrew D. Greentree; Takeshi Ohshima
  Materials Science Forum, Volume：1004, First page：355, Last page：360, 2020
  This paper reports optical propertites of negatively charged NCVSi- centers in silicon carbide (a nitrogen substituting for a carbon atom adjacent to a silicon vacancy) whose emission wavlength is 1100-1500 nm at room temperature. High-purity semi-insulating (HPSI) 4H-SiCs are implanted with high energy N ion beams and subsequently thermally annealed to form NCVSi centers. We investigated a wide range of N ion implantation dose using a micro ion beam implantation technique and observed the photoluminescence intensity from the SiC-NV centers. We show that under conditions of heavy implantation, the excitation laser power excites residual defects and their fluorescences intereferes with the emission from the NCVSi- centers. These results allow us to clarify the requirements to optically detect isolated single NCVSi- centers at lightly implanted conditions.
  Trans Tech Publications Ltd, English, International conference proceedings
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.1004.355
  DOI ID：10.4028/www.scientific.net/MSF.1004.355, ISSN：1662-9752, SCOPUS ID：85089803119
• Enhancement of ODMR contrasts of silicon vacancy in SiC by thermal treatment　　　　　　　　　　　　　　　
  Yoji Chiba; Yuichi Yamazaki; Shin-Ichiro Sato; Takahiro Makino; Naoto Yamada; Takahiro Satoh; Yasuto Hijikata; Takeshi Ohshima
  Materials Science Forum, Volume：1004, First page：337, Last page：342, 2020
  We demonstrated the enhancement of the optically detected magnetic resonance (ODMR) contrast of negatively charged silicon vacancy (VSi-) in SiC by thermal treatment. To create a high density of VSi-, Proton Beam Writing (PBW) was conducted. After annealing at 600 °C, the ODMR contrast showed the highest value in the investigated temperature range. At lower irradiation fluence, despite no significant change was observed in terms of VSi- PL intensity, the improvement of the ODMR contrast was observed. Considering defect energy levels and annealing behavior previously reported, it was deduced that the improvement of the ODMR contrast was caused by the reduction of other irradiation-induced defect centers, such as EH3 center.
  Trans Tech Publications Ltd, English, International conference proceedings
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.1004.337
  DOI ID：10.4028/www.scientific.net/MSF.1004.337, ISSN：1662-9752, SCOPUS ID：85089798448
• Effects of nitrogen impurity concentration on nitrogen-vacancy center formation in 4h-sic　　　　　　　　　　　　　　　
  Takuma Narahara; Shin-Ichiro Sato; Kazutoshi Kojima; Yuichi Yamazaki; Yasuto Hijikata; Takeshi Ohshima
  Materials Science Forum, Volume：1004, First page：349, Last page：354, 2020
  Spin defects of which states can be manipulated in Silicon Carbide (SiC) have drawn considerable attention because of their applications to quantum technologies. The single negatively-charged pairs of VSi and nitrogen atom (N) on an adjacent C site (NCVSi- center) in SiC is suitable for them. This paper reports the formation of NCVSi- centers on 4H-SiC epilayers with different nitrogen concentrations using light/heavy ion irradiation and subsequent thermal annealing. The formation of NCVSi- centers is characterized by the near infrared photoluminescence (PL) spectroscopy. It is shown that the PL intensity from NCVSi- centers depends on the N concentration and the ion irradiation conditions. The PL intensity increases monotonically with increasing the N concentration when the N concentration is above 2.6×1016 cm-3, whereas no linear correlation between them does not appear below that N concentration. Although the PL intensity increases with increasing defects induced by ion irradiation, the PL quenching due to neighboring residual defects appear at above the areal vacancy concentration of 1017 vac/cm2 and the broad Raman scattering spectra originated from vibration modes of amorphized regions hinder the PL from NCVSi- centers at above 1018 vac/cm2. The formation mechanism and the charge state stability of NCVSi- centers are discussed based on the obtained results.
  Trans Tech Publications Ltd, English, International conference proceedings
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.1004.349
  DOI ID：10.4028/www.scientific.net/MSF.1004.349, ISSN：1662-9752, SCOPUS ID：85089796074
• Optically detected magnetic resonance study of 3d arrayed silicon vacancies in sic pn diodes
  Yamazaki, Y.; Chiba, Y.; Sato, S.-I.; Makino, T.; Yamada, N.; Satoh, T.; Kojima, K.; Hijikata, Y.; Tsuchida, H.; Hoshino, N.; Lee, S.-Y.; Ohshima, T.
  Materials Science Forum, Volume：1004 MSF, 2020
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.1004.343
  DOI ID：10.4028/www.scientific.net/MSF.1004.343, ISSN：1662-9752, ORCID：80841223, SCOPUS ID：85089809284
• Creation of color centers in sic pn diodes using proton beam writing
  Chiba, Y.; Yamazaki, Y.; Makino, T.; Sato, S.-I.; Yamada, N.; Satoh, T.; Kojima, K.; Lee, S.-Y.; Hijikata, Y.; Ohshima, T.
  Materials Science Forum, Volume：963 MSF, 2019, [Reviewed]
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.963.709
  DOI ID：10.4028/www.scientific.net/MSF.963.709, ORCID：69201932, SCOPUS ID：85071847159
• Macroscopic simulations of the SiC thermal oxidation process based on the Si and C emission model　　　　　　　　　　　　　　　
  Hijikata, Y.
  Diamond and Related Materials, Volume：92, First page：253, Last page：258, 2019, [Reviewed]
  The interface defects formed at the oxide-SiC interface impact not only on channel mobility of MOSFET but also on many scenes such as generation or extinction of Si/C atom vacancies and formation of single-photon sources. Therefore, it is very important to know the oxidation mechanism of SiC more in detail. We have previously proposed a unified SiC oxidation model based on the Si and C emission phenomenon. In addition, it has been revealed that this model accurately reproduces the oxide growth rate in the entire oxide thickness range for various oxidation conditions and substrate surface orientations. In this report, based on the experimental verifications for the four oxidation stages deduced from this unified oxidation model, the validity of this model was reviewed. Furthermore, the interface-emitted Si and C concentrations were simulated for various oxidation temperatures and substrate surface orientations. Based on the simulation results together with experimental results of interface state density, the optimum oxide growth condition has been discussed.
  Elsevier {BV}, English, Scientific journal
  DOI：https://doi.org/10.1016/j.diamond.2019.01.012
  DOI ID：10.1016/j.diamond.2019.01.012, ISSN：0925-9635, eISSN：1879-0062, ORCID：69201950, SCOPUS ID：85060283318, Web of Science ID：WOS:000461129800033
• First-principles study of oxygen-related defects on 4H-SiC surface: The effects of surface amorphous structure　　　　　　　　　　　　　　　
  Matsushita, Y.-I.; Furukawa, Y.; Hijikata, Y.; Ohshima, T.
  Applied Surface Science, Volume：464, First page：451, Last page：454, 2019, [Reviewed]
  We report our first-principles calculations that clarify the electronic states of oxygen-related defects in the 4H-SiC bulk and on the 4H-SiC surface and how they are affected by the surface amorphous structure due to oxidation. It is experimentally reported that thermally oxidized 4H-SiC contains an abundant amount of single-photon sources on its surface (surface SPSs) and that their emitting wavelengths have variance. However, the microscopic mechanism is not clarified yet. In our work, we demonstrate that the energy levels of the oxygen-related defects on the surface are altered sensitively by the local atomic structure of the amorphous surface leading to variations in the wavelengths.
  Elsevier {BV}, English, Scientific journal
  DOI：https://doi.org/10.1016/j.apsusc.2018.09.072
  DOI ID：10.1016/j.apsusc.2018.09.072, ISSN：0169-4332, eISSN：1873-5584, ORCID：69201997, SCOPUS ID：85053384490, Web of Science ID：WOS:000447744200054
• Radiation response of negative gate biased SiC MOSFETs　　　　　　　　　　　　　　　
  Takeyama, A.; Makino, T.; Okubo, S.; Tanaka, Y.; Yoshie, T.; Hijikata, Y.; Ohshima, T.
  Materials, Volume：12, Number：7, First page：2741, Last page：2741, 2019, [Reviewed]
  Silicon carbide (SiC) metal-oxide-semiconductor field effect transistors (MOSFETs) are expected as power electronic devices for high radiative conditions, including nuclear plants and space. Radiation response of commercial-grade prototype SiC MOSFETs with applying the gate bias is of interest, in terms of installation of the device in robots or sensors working under such radioactive circumstances. Due to gamma-rays irradiation, the threshold voltages (V-th) of samples with un- and negative-biased up to -4.5 V slightly shift toward the negative voltage side. In contrast, the positive bias of 2.25 V shifts V-th more negatively. Positive charge densities trapped in the gate oxide of un- and positive-biased samples increased with increasing dose. However, no significant increase was observed for negative-biased samples of -2.25 and -4.5 V. We calculated characteristic parameters for the accumulation of holes in the gate oxide, sigma(p)J(p) which is defined as the product of current density due to holes generated by irradiation and capture cross section for a hole in a trap, and it is lower for these negative biased samples compared with the unbiased case. Application of appropriate negative gate biases to SiC MOSFETs during irradiation suppresses accumulation of positive charges in the gate oxide and negative shift of V-th, due to irradiation.
  {MDPI} {AG}, English, Scientific journal
  DOI：https://doi.org/10.3390/ma12172741
  DOI ID：10.3390/ma12172741, eISSN：1996-1944, ORCID：69201964, SCOPUS ID：85071867226, Web of Science ID：WOS:000488880300094
• Formation of nitrogen-vacancy centers in 4H-SiC and their near infrared photoluminescence properties　　　　　　　　　　　　　　　
  Sato, S.-I.; Narahara, T.; Abe, Y.; Hijikata, Y.; Umeda, T.; Ohshima, T.
  Journal of Applied Physics, Volume：126, Number：8, 2019, [Reviewed]
  NCVSi- centers in SiC [nitrogen-vacancy (NV) centers], which produce near-infrared (NIR) photoluminescence (PL) at room temperature, is expected to have applications as quantum sensors for in vivo imaging and sensing. To realize quantum sensing using NV centers, clarification of the formation mechanism as well as control of the high-density formation is necessary. This paper reports a comprehensive investigation on the NIR-PL properties originating from NV centers in high purity semi-insulating and nitrogen (N) contained 4H-SiC substrates formed by ion beam irradiation and subsequent thermal annealing. It is shown that NV centers are exclusively formed by the contained N as impurities rather than the implanted N, and also the heavier ion irradiations induce the NV center formation effectively than the lighter ion irradiations. The study on thermal annealing at different temperatures reveals that the optimal temperature is 1000 degrees C. From the results of temperature dependence on the PL intensity, it is shown that little thermal quenching of the PL intensity appears at room temperature and the PL signal is collected even at 783K. The formation mechanism of NV centers is also discussed based on the obtained results. Published under license by AIP Publishing.
  AMER INST PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1063/1.5099327
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85071323431&origin=inward
  DOI ID：10.1063/1.5099327, ISSN：0021-8979, eISSN：1089-7550, ORCID：69201955, SCOPUS ID：85071323431, Web of Science ID：WOS:000483884600018
• Various single photon sources observed in SiC pin diodes
  Tsunemi, H.; Honda, T.; Makino, T.; Onoda, S.; Sato, S.-I.; Hijikata, Y.; Ohshima, T.
  Materials Science Forum, Volume：924 MSF, 2018, [Reviewed]
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.924.204
  DOI ID：10.4028/www.scientific.net/MSF.924.204, ORCID：47642246, SCOPUS ID：85049011254
• Oxygen-incorporated single-photon sources observed at the surface of silicon carbide crystals　　　　　　　　　　　　　　　
  Hijikata, Y.; Horii, T.; Furukawa, Y.; Matsushita, Y.-I.; Ohshima, T.
  Journal of Physics Communications, Volume：2, Number：11, 2018, [Reviewed]
  The formation of high-brightness single-photon sources (SPSs) that emit single photons at room temperature was recently confirmed in oxygen-annealed SiC semiconductors (surface SPSs.) However, the defect structure of surface SPSs remains unclear, which makes device fabrication and property control difficult. To verify the incorporation of oxygen in surface SPSs, we fabricated SPSs using stable O-18 isotopes as oxidants. By comparing this to the case of natural oxygen annealing, we found that the SP emission spectra for the O-18 sample tended to have shorter peak wavelengths, slightly narrower peak widths, and higher intensities. Thus, it appeared that, in the case of the O-18 sample, the phonon sideband was located closer to the zero-phonon line and that oxygen was incorporated into the defects attributed to the surface SPS.
  {IOP} Publishing, English, Scientific journal
  DOI：https://doi.org/10.1088/2399-6528/aaede4
  DOI ID：10.1088/2399-6528/aaede4, ISSN：2399-6528, ORCID：69201936, SCOPUS ID：85060292412, Web of Science ID：WOS:000456498500004
• Electrically controllable position-controlled color centers created in SiC pn junction diode by proton beam writing　　　　　　　　　　　　　　　
  Yamazaki, Y.; Chiba, Y.; Makino, T.; Sato, S.-I.; Yamada, N.; Satoh, T.; Hijikata, Y.; Kojima, K.; Lee, S.-Y.; Ohshima, T.
  Journal of Materials Research, Volume：33, Number：20, First page：3355, Last page：3361, 2018, [Reviewed]
  Single photon sources (SPS) are an important building block for realizing quantum technologies for computing, communication, and sensing. For industrialization, electrically controllable color centers acting as SPS are required. We have demonstrated the creation of electrically controllable silicon vacancies (V(Si)s) in the SiC pn junction diode fabricated by proton beam writing (PBW). PBW was successfully used to introduce electrically controllable V-Si without degradation of the diode performance. The dependence of the electroluminescence (EL) and photoluminescence (PL) intensities from V-Si on H+ fluence revealed that the emission efficiency of EL is less than that of PL. For EL, the supply of carriers (electrons and/or holes) was restricted due to the resistive region around each V-Si introduced by PBW. The results suggest that further improvement in the V-Si creation process without defects acting as majority carrier removal centers (highly resistive region) and nonradiative centers by optimization of PBW conditions are key points to realize highly sensitive quantum sensors using V-Si.
  CAMBRIDGE UNIV PRESS, English, Scientific journal
  DOI：https://doi.org/10.1557/jmr.2018.302
  DOI ID：10.1557/jmr.2018.302, ISSN：0884-2914, eISSN：2044-5326, ORCID：69201975, SCOPUS ID：85052912484, Web of Science ID：WOS:000452651700001
• Generation of stacking faults in 4H-SiC epilayer induced by oxidation　　　　　　　　　　　　　　　
  Asafuji, R.; Hijikata, Y.
  Materials Research Express, Volume：5, Number：1, 2018, [Reviewed]
  Stacking faults (SFs) generated by thermal oxidation of a 4H-SiC epilayer were investigated using photoluminescence (PL) imaging/mapping and transmission electron microscopy (TEM). Line-shaped and band-shaped faults perpendicular to the off-cut direction in the epilayer were formed by thermal oxidation. In addition, the line-shaped faults increased and were stretched with the oxidation time. Triangular SFs were also formed under UV laser irradiation from both types of faults as starting points, and expanded along the basal plane toward the sample surface. The oxidation time dependence of the line-shaped fault density indicated that line-shaped faults are predominantly formed close to 1100 degrees C. The atomic structures of the line-shaped faults and triangular SFs were observed using cross-sectional TEM. Line-shaped faults were present at the epilayer/bulk interface with which double Shockley SFs stretch into the bulk layer. PL mapping results indicated that the band-shaped faults are probably intrinsic Frank-type SFs.
  {IOP} Publishing, English, Scientific journal
  DOI：https://doi.org/10.1088/2053-1591/aaa00c
  DOI ID：10.1088/2053-1591/aaa00c, ISSN：2053-1591, ORCID：69201994, SCOPUS ID：85041630558, Web of Science ID：WOS:000419328400003
• Room Temperature Electrical Control of Single Photon Sources at 4H-SiC Surface　　　　　　　　　　　　　　　
  Sato, S.-I.; Honda, T.; Makino, T.; Hijikata, Y.; Lee, S.-Y.; Ohshima, T.
  ACS Photonics, Volume：5, Number：8, First page：3159, Last page：3165, 2018, [Reviewed]
  Single photon source (SPS) providing nonclassical light states on demand is one of the key technologies for the application of quantum communication and optical quantum computer. In this paper, room temperature electrical control of single photon emission from defects at 4H-SiC surface is presented. Planar-type 4H-SiC p(+)nn(+) diodes are fabricated and defects that act as SPS are formed on the surface of n-type epi-layer by field oxidation process. The photon emission properties of SPSs are investigated using a home-built confocal microscopy. Results show that the electroluminescence (EL) intensity of SPS can be controlled by minority carrier injection of forward bias voltages, while the photoluminescence (PL) intensity of SPS can be controlled by reverse bias voltages. No significant variations due to applied bias voltages are observed in the EL and PL spectra, indicating the defect structure and charge state are unchanged. The PL intensity modulation by switching a reverse bias voltage is also demonstrated.
  American Chemical Society ({ACS}), English, Scientific journal
  DOI：https://doi.org/10.1021/acsphotonics.8b00375
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85047601078&origin=inward
  DOI ID：10.1021/acsphotonics.8b00375, ISSN：2330-4022, eISSN：2330-4022, ORCID：69201946, SCOPUS ID：85047601078, Web of Science ID：WOS:000442185900025
• Creation and functionalization of defects in SiC by proton beam writing
  Ohshima, T.; Honda, T.; Onoda, S.; Makino, T.; Haruyama, M.; Kamiya, T.; Satoh, T.; Hijikata, Y.; Kada, W.; Hanaizumi, O.; Lohrmann, A.; Klein, J.R.; Johnson, B.C.; McCallum, J.C.; Castelletto, S.; Gibson, B.C.; Kraus, H.; Dyakonov, V.; Astakhov, G.V.
  Materials Science Forum, Volume：897 MSF, 2017, [Reviewed]
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.897.233
  DOI ID：10.4028/www.scientific.net/MSF.897.233, ORCID：47642233, SCOPUS ID：85020032477
• Three-Dimensional Proton Beam Writing of Optically Active Coherent Vacancy Spins in Silicon Carbide　　　　　　　　　　　　　　　
  Kraus, H.; Simin, D.; Kasper, C.; Suda, Y.; Kawabata, S.; Kada, W.; Honda, T.; Hijikata, Y.; Ohshima, T.; Dyakonov, V.; Astakhov, G. V.
  Nano Letters, Volume：17, Number：5, 2017, [Reviewed]
  Scientific journal
  DOI：https://doi.org/10.1021/acs.nanolett.6b05395
  DOI ID：10.1021/acs.nanolett.6b05395, ORCID：33755623, SCOPUS ID：85019179211, Web of Science ID：WOS:000401307300018
• Optimum structures for gamma-ray radiation resistant SiC-MOSFETs　　　　　　　　　　　　　　　
  Mitomo, S.; Matsuda, T.; Murata, K.; Yokoseki, T.; Makino, T.; Takeyama, A.; Onoda, S.; Ohshima, T.; Okubo, S.; Tanaka, Y.; Kandori, M.; Yoshie, T.; Hijikata, Y.
  Physica Status Solidi (A) Applications and Materials Science, Volume：214, Number：4, 2017, [Reviewed]
  In order to develop highly radiation-tolerant SiC MOSFETs, we investigated the dependence of the gamma-ray radiation response on the gate oxide thickness and nitridation processes, used for oxide growth oxide (60 nm) showed a rapid decrease in the threshold voltage shift Delta V-th of more than 400 kGy, and transitioned to the normally-on state at lower doses than those with a thin gate oxide (35 nm). The MOSFETs with gate oxides treated with lower concentrations of N2O (10%) demonstrated a higher radiation tolerance (Delta V-th, channel mobility, and subthreshold swing) than with a 100% N2O treatment. The MOSFETs with more p-well implantation steps (three steps) showed a smaller negative shift of the threshold voltage relative to those implanted with two steps. (C) 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssa.201600425
  DOI ID：10.1002/pssa.201600425, ISSN：1862-6300, eISSN：1862-6319, ORCID：47642240, SCOPUS ID：85012884011, Web of Science ID：WOS:000402158300025
• Impacts of gate bias and its variation on gamma-ray irradiation resistance of SiC MOSFETs　　　　　　　　　　　　　　　
  Murata, K.; Mitomo, S.; Matsuda, T.; Yokoseki, T.; Makino, T.; Onoda, S.; Takeyama, A.; Ohshima, T.; Okubo, S.; Tanaka, Y.; Kandori, M.; Yoshie, T.; Hijikata, Y.
  Physica Status Solidi (A) Applications and Materials Science, Volume：214, Number：4, 2017, [Reviewed]
  Gamma-ray irradiation into vertical type n-channel hexagonal (4H)-silicon carbide (SiC) metal-oxide-semiconductor field effect transistors (MOSFETs) was performed under various gate biases. The threshold voltage for the MOSFETs irradiated with a constant positive gate bias showed a large negative shift, and the shift slightly recovered above 100 kGy. For MOSFETs with non- and a negative constant biases, no significant change in threshold voltage, V-th, was observed up to 400 kGy. By changing the gate bias from positive bias to either negative or non- bias, the Vth significantly recovered from the large negative voltage shift induced by 50 kGy irradiation with positive gate bias after only 10 kGy irradiation with either negative or zero bias. It indicates that the positive charges generated in the gate oxide near the oxide-SiC interface due to irradiation were removed or recombined instantly by the irradiation under zero or negative biases. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssa.201600446
  DOI ID：10.1002/pssa.201600446, ISSN：1862-6300, eISSN：1862-6319, ORCID：47642238, SCOPUS ID：84996555465, Web of Science ID：WOS:000402158300026
• Gamma-ray irradiation response of the motor-driver circuit with SiC MOSFETs
  Kobayashi, Y.; Yokozeki, T.; Matsuda, T.; Mitomo, S.; Murata, K.; Hachisuka, M.; Kaneko, Y.; Makino, T.; Takeyama, A.; Onoda, S.; Ohshima, T.; Tanaka, Y.; Kandori, M.; Yoshie, T.; Hijikata, Y.
  Materials Science Forum, Volume：858, 2016, [Reviewed]
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.858.868
  DOI ID：10.4028/www.scientific.net/MSF.858.868, ORCID：47642235, SCOPUS ID：84971498978
• Effect of gamma-ray irradiation on the device process-induced defects in 4H-SiC epilayers　　　　　　　　　　　　　　　
  Miyazaki, T.; Makino, T.; Takeyama, A.; Onoda, S.; Ohshima, T.; Tanaka, Y.; Kandori, M.; Yoshie, T.; Hijikata, Y.
  Superlattices and Microstructures, Volume：99, 2016, [Reviewed]
  Scientific journal
  DOI：https://doi.org/10.1016/j.spmi.2016.03.005
  DOI ID：10.1016/j.spmi.2016.03.005, ORCID：31489770, SCOPUS ID：84960365133, Web of Science ID：WOS:000390630200035
• Change in characteristics of SiC MOSFETs by gamma-ray irradiation at high temperature　　　　　　　　　　　　　　　
  Matsuda, T.; Yokoseki, T.; Mitomo, S.; Murata, K.; Makino, T.; Abe, H.; Takeyama, A.; Onoda, S.; Tanaka, Y.; Kandori, M.; Yoshie, T.; Hijikata, Y.; Ohshima, T.
  Materials Science Forum, Volume：858, First page：860, Last page：863, 2016, [Reviewed]
  Radiation response of 4H-SiC vertical power Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) was investigated at 150ºC up to 10.4 MGy. Until irradiation at 1.2 MGy, the drain current – gate voltage curves of the SiC MOSFETs shifted to the negative voltage side, and the leakage of drain current at gate voltages below threshold voltage increased with increasing absorbed dose. However, no significant change in the electrical characteristics of SiC MOSFETs was observed at doses above 1.2 MGy. For blocking characteristics, there were no degradations of the SiC MOSFETs irradiated at 150oC even after irradiated at 10.4 MGy.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.858.860
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84971500986&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.858.860, ISSN：0255-5476, eISSN：1662-9752, ORCID：47642241, SCOPUS ID：84971500986
• Unified theory of silicon carbide oxidation based on the Si and C emission model　　　　　　　　　　　　　　　
  Goto, D.; Hijikata, Y.
  Journal of Physics D: Applied Physics, Volume：49, Number：22, 2016, [Reviewed]
  We have attempted to establish a unified theory of SiC oxidation by reproducing all the SiC oxide growth rates on the (0 0 0 1) Si-face, (1 1 (2) over bar 0) a-face and (0 0 0 (1) over bar) C-face at various oxidation temperatures and oxide partial pressures. Growth rates were calculated using the Si and C emission model and were confirmed to fully reproduce the observed data when an enhanced surface oxide growth rate was added to the previously defined growth rate. The parameters deduced from the calculations indicated that the activation energy for the initial interfacial reaction rate corresponds to the number of Si back-bond(s) on the crystalline surface. Although the C emission ratio was found to have no significant dependence on the surface orientation, the Si emission ratio varied significantly and so likely determines the oxide growth rate. The densities of Si and C interstitials at the SiC-oxide interface were simulated both on the oxide and SiC substrate sides, and the optimal oxidation sequence is discussed in terms of the formation of the interface state.
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.1088/0022-3727/49/22/225103
  DOI ID：10.1088/0022-3727/49/22/225103, ISSN：0022-3727, eISSN：1361-6463, ORCID：69201938, SCOPUS ID：84971506934, Web of Science ID：WOS:000377410800006
• Improvement of radiation response of SiC MOSFETs under high temperature and humidity conditions　　　　　　　　　　　　　　　
  Takeyama, A.; Matsuda, T.; Yokoseki, T.; Mitomo, S.; Murata, K.; Makino, T.; Onoda, S.; Okubo, S.; Tanaka, Y.; Kandori, M.; Yoshie, T.; Hijikata, Y.; Ohshima, T.
  Japanese Journal of Applied Physics, Volume：55, Number：10, 2016, [Reviewed]
  The response of hexagonal (4H) silicon carbide (SiC) power metal-oxide-semiconductor field effect transistors (MOSFETs) to gamma-ray irradiation was investigated under elevated temperature and humid conditions. The shift in drain current-gate voltage (ID-VG) curves towards negative voltages and the leakage of ID with a current hump due to elevated temperature irradiation were suppressed under high humidity conditions relative to dry conditions. This result can be explained in terms of the reduction in trapped oxide charge and oxide-SiC interface traps generated by irradiation due to the humid conditions. In addition, during irradiation at elevated temperature in humid conditions, electron traps at the oxide-SiC interface obviously decrease at doses above 100 kGy. (C) 2016 The Japan Society of Applied Physics
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.7567/JJAP.55.104101
  DOI ID：10.7567/JJAP.55.104101, ISSN：0021-4922, eISSN：1347-4065, ORCID：69201952, SCOPUS ID：84989321764, Web of Science ID：WOS:000384090600001
• Radiation response of silicon carbide metal-oxide-semiconductor transistors in high dose region　　　　　　　　　　　　　　　
  Ohshima, T.; Yokoseki, T.; Murata, K.; Matsuda, T.; Mitomo, S.; Abe, H.; Makino, T.; Onoda, S.; Hijikata, Y.; Tanaka, Y.; Kandori, M.; Okubo, S.; Yoshie, T.
  Japanese Journal of Applied Physics, Volume：55, Number：1, First page：01AD01, 2016, [Reviewed]
  Radiation response of vertical structure hexagonal (4H) silicon carbide (SiC) power metal-oxide-semiconductor field effect transistors (MOSFETs) was investigated up to 5.8 MGy. The drain current-gate voltage curves for the MOSFETs shifted from positive to negative voltages due to irradiation. However, the drain current-gate voltage curve shifts for the MOSFETs irradiated at 150 degrees C was smaller than those irradiated at room temperature. Thus, the shift of threshold voltage due to irradiation was suppressed by irradiation at 150 degrees C. No significant change or slight decrease in subthreshold voltage swing for the MOSFETs irradiated at 150 degrees C was observed. The value of channel mobility increased due to irradiation, and the increase was enhanced by irradiation at 150 degrees C comparing to irradiation at RT. (C) 2016 The Japan Society of Applied Physics
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.7567/JJAP.55.01AD01
  DOI ID：10.7567/JJAP.55.01AD01, ISSN：0021-4922, eISSN：1347-4065, ORCID：69201939, SCOPUS ID：84953216736, Web of Science ID：WOS:000369014400042
• Recovery of the electrical characteristics of SiC MOSFETs irradiated with gamma-rays by thermal treatments　　　　　　　　　　　　　　　
  Yokoseki, T.; Abe, H.; Makino, T.; Onoda, S.; Tanaka, Y.; Kandori, M.; Yoshie, T.; Hijikata, Y.; Ohshima, T.
  Materials Science Forum, Volume：821-823, First page：705, Last page：708, 2015, [Reviewed]
  Effects of gamma-ray irradiation and subsequent thermal annealing on the characteristics of vertical structure power Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) fabricated on 4H-SiC were studied. After irradiation at 1.2 MGy, the drain current – gate voltage curves of the MOSFETs shifted to the negative voltage side and the leakage drain current at inverse voltage increased. No significant change in the degraded electrical characteristics of SiC MOSFETs was observed by room temperature annealing. The degraded characteristics of SiC MOSFETs began to recover by annealing above 120 °C, and their characteristics reached almost the initial ones by annealing at 360 °C.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.821-823.705
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84950327360&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.821-823.705, ISSN：0255-5476, eISSN：1662-9752, ORCID：47642232, SCOPUS ID：84950327360
• Si and C emission into the oxide layer during the oxidation of silicon carbide and its influence on the oxidation rate　　　　　　　　　　　　　　　
  Hijikata, Y.; Asafuji, R.; Konno, R.; Akasaka, Y.; Shinoda, R.
  AIP Advances, Volume：5, Number：6, First page：067128, Last page：067128, 2015, [Reviewed]
  Si and C emission into the oxide layer during the oxidation of silicon carbide and SiO2 growth on the oxide surface were experimentally confirmed from depth profiles of oxidized HfO2/SiC structures. With longer oxidation times, surface SiO2 growth transitioned to oxide/SiC interface growth. The influence of Si and C emission on the oxidation rate was investigated by real-time measurements of the oxide growth rate. Experimental observations of annealing-inserted oxidation and two-temperature oxidation indicated that the emission suppressed the oxidation rate. (C) 2015 Author(s).
  {AIP} Publishing, English, Scientific journal
  DOI：https://doi.org/10.1063/1.4922536
  DOI ID：10.1063/1.4922536, ISSN：2158-3226, ORCID：69201957, SCOPUS ID：84934978437, Web of Science ID：WOS:000357608000028
• Photoluminescence study of oxidation-induced stacking faults in 4H-SiC epilayers　　　　　　　　　　　　　　　
  Miyano, Y.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
  Materials Science Forum, Volume：821-823, First page：327, Last page：330, 2015, [Reviewed]
  © (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.
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.821-823.327
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84950321920&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.821-823.327, ISSN：0255-5476, eISSN：1662-9752, ORCID：47642247, SCOPUS ID：84950321920
• Surface orientation dependence of SiC oxidation process studied by in-situ spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Goto, D.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
  Materials Science Forum, Volume：821-823, First page：371, Last page：374, 2015, [Reviewed]
  © (2014) Trans Tech Publications, Switzerland. We performed real-time observations of SiC oxidation at various temperatures by in-situ spectroscopic ellipsometry using a Si-face, an a-face and a C-face substrates. We calculated oxide growth rates based on “Si-C emission model,” taking into account the emission of interfacial Si and C atoms from the SiC–SiO2 interface. The calculated values well reproduced the oxide thickness dependence of oxide growth rates. We discussed the SiC oxidation mechanism using the parameters deduced from the calculations.
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.821-823.371
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84950341587&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.821-823.371, ISSN：0255-5476, eISSN：1662-9752, ORCID：47642243, SCOPUS ID：84950341587
• Molecular beam epitaxial growth of intermediate-band materials based on GaAs:N δ-doped superlattices　　　　　　　　　　　　　　　
  Suzuki, T.; Osada, K.; Yagi, S.; Naitoh, S.; Shoji, Y.; Hijikata, Y.; Okada, Y.; Yaguchi, H.
  Japanese Journal of Applied Physics, Volume：54, Number：8, First page：08KA07, 2015, [Reviewed]
  We fabricated GaAs: N delta-doped superlattices (SLs) by molecular beam epitaxy and investigated their potential as an intermediate-band photoabsorber in high-efficiency solar cells. The N area concentration in a N delta-doped layer was well controlled by adjusting the fabrication conditions, and the SLs with the average N composition of up to 1.5% were obtained. The SL minibands related to the N-induced E+ and E- conduction subbands were formed with well-separated bottom energies of up to 0.4 eV, indicating the suitability of this material system for use in intermediate-band solar cells. A two-step photoabsorption process in a solar cell with the SL absorber was successfully demonstrated through external quantum efficiency measurements under additional infrared illumination at room temperature. (C) 2015 The Japan Society of Applied Physics
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.7567/JJAP.54.08KA07
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84938504709&origin=inward
  DOI ID：10.7567/JJAP.54.08KA07, ISSN：0021-4922, eISSN：1347-4065, ORCID：69201956, SCOPUS ID：84938504709, Web of Science ID：WOS:000358662900008
• Control of intermediate-band configuration in GaAs:N δ-doped superlattice　　　　　　　　　　　　　　　
  Osada, K.; Suzuki, T.; Yagi, S.; Naitoh, S.; Shoji, Y.; Hijikata, Y.; Okada, Y.; Yaguchi, H.
  Japanese Journal of Applied Physics, Volume：54, Number：8, First page：08KA04, 2015, [Reviewed]
  GaAs: N delta-doped superlattices (SLs) consisting of alternating layers of undoped and N delta-doped GaAs were fabricated by molecular beam epitaxy (MBE) as possible candidates for the light-absorbing material of intermediate-band solar cells (IBSCs). Since the energy gaps in IBSCs need to be adjusted to optimum values to achieve sufficiently high conversion efficiency, it is important to control precisely the band configuration of intermediate-band (IB) materials. In this study, we demonstrated the control of the IB energy configuration in GaAs: N delta-doped SLs by changing their structural parameters. Optical transitions due to the SL minibands related to the N-induced conduction subbands E+ and E- were clearly observed and the transition energies depended systematically on the N area density and period length of the SLs. Conversion efficiency calculations based on the detailed balance model indicated that IBSCs with an efficiency of nearly 60% are achievable by using the fabricated GaAs: N delta-doped SLs. (C) 2015 The Japan Society of Applied Physics
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.7567/JJAP.54.08KA04
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84938516127&origin=inward
  DOI ID：10.7567/JJAP.54.08KA04, ISSN：0021-4922, eISSN：1347-4065, ORCID：69201960, SCOPUS ID：84938516127, Web of Science ID：WOS:000358662900005
• Photoluminescence study of oxidation-induced faults in 4H-SiC epilayers　　　　　　　　　　　　　　　
  Miyano, Y.; Asafuji, R.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
  AIP Advances, Volume：5, Number：12, First page：127116, Last page：127116, 2015, [Reviewed]
  We investigated the effect of thermal oxidation on crystalline faults in 4H-SiC epilayers using photoluminescence imaging. We found that a comb-shaped dislocation array was deformed by thermal oxidation. We also found that line-shaped faults perpendicular to the off-cut direction were formed during oxidation and were stretched and increased with the oxidation time. Since these line-shaped faults were peculiar to the oxidation and stretched/increased with the oxide growth, they were identified as oxidation-induced stacking faults as seen in Si oxidation. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
  {AIP} Publishing, English, Scientific journal
  DOI：https://doi.org/10.1063/1.4938126
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84952672264&origin=inward
  DOI ID：10.1063/1.4938126, ISSN：2158-3226, eISSN：2158-3226, ORCID：69201979, SCOPUS ID：84952672264, Web of Science ID：WOS:000367596300016
• Growth temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy　　　　　　　　　　　　　　　
  Jin, R.G.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
  Japanese Journal of Applied Physics, Volume：54, Number：5, First page：051201, 2015, [Reviewed]
  We have quantitatively studied the temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy using secondary ion mass spectroscopy. It was found that a significant number of Er atoms segregate to the growing surface at temperatures of 400 degrees C and above and that the segregation decay length is approximately 0.5 mu m at 500 degrees C, indicating that the incorporation ratio of Er atoms into GaAs is less than 10(-3). In contrast to the growth at higher temperatures, GaAs overlayer growth at a temperature as low as 300 degrees C is effective in suppressing the surface segregation of Er and obtaining delta-doped structures. (C) 2015 The Japan Society of Applied Physics
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.7567/JJAP.54.051201
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84983072013&origin=inward
  DOI ID：10.7567/JJAP.54.051201, ISSN：0021-4922, eISSN：1347-4065, ORCID：69201988, SCOPUS ID：84983072013, Web of Science ID：WOS:000354980300009
• Differences in SiC thermal oxidation process between crystalline surface orientations observed by in-situ spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Goto, D.; Hijikata, Y.; Yagi, S.; Yaguchi, H.
  Journal of Applied Physics, Volume：117, Number：9, First page：095306, Last page：095306, 2015, [Reviewed]
  For a better understanding of the SiC oxidation mechanism, we investigated differences in the oxidation process for surfaces with different crystal orientations. Real-time observations of oxidation processes for (0001) Si-face, (11 (2) over bar0) a-face, and (000 (1) over bar) C-face substrates at various oxidation temperatures were performed using in-situ spectroscopic ellipsometry. Massoud's empirical equation, which is composed of the classical Deal-Grove equation added by an exponential term, was applied to the observed growth rates and the oxidation rate parameters were extracted by curve fitting. The SiC oxidation mechanism is discussed in terms of the oxidation temperature dependence and surface orientation dependence of the oxidation rate parameters. (C) 2015 AIP Publishing LLC.
  {AIP} Publishing, English, Scientific journal
  DOI：https://doi.org/10.1063/1.4914050
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84924310120&origin=inward
  DOI ID：10.1063/1.4914050, ISSN：0021-8979, eISSN：1089-7550, ORCID：69201941, SCOPUS ID：84924310120, Web of Science ID：WOS:000351134400041
• Si emission into the oxide layer during oxidation of silicon carbide　　　　　　　　　　　　　　　
  Hijikata, Y.; Akasaka, Y.; Yagi, S.; Yaguchi, H.
  Materials Science Forum, Volume：778-780, First page：553, Last page：556, 2014, [Reviewed]
  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.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.778-780.553
  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, ORCID：69201974, SCOPUS ID：84896066589, Web of Science ID：WOS:000336634100130
• 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, Volume：211, Number：4, First page：752, Last page：755, 2014, [Reviewed]
  We have studied the temperature dependence of optical transitions in dilute GaAsN alloys using photoreflectance (PR). A delocalized-state transition is clearly observed in PR spectra while several localized-state emission lines due to isoelectronic centers appear in photoluminescence spectra. The energy of optical transitions observed in PR spectra is in agreement with the excitonic transition energy in photoluminescence excitation spectra, clearly showing that the optical transitions in PR spectra are excitonic transitions. We analyzed the temperature dependence of the excitonic transition energies using the Bose-Einstein statistical expression, and found that even dilute alloys follow the same trend as GaAsN alloys with higher nitrogen concentrations. We discuss the coexistence of localized and delocalized states in dilute GaAsN alloys in terms of the random distribution of N atoms.
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssa.201300462
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84897986009&origin=inward
  DOI ID：10.1002/pssa.201300462, ISSN：1862-6300, eISSN：1862-6319, ORCID：69201993, SCOPUS ID：84897986009, Web of Science ID：WOS:000333911800006
• Enhanced optical absorption due to E+-related band transition in GaAs:N δ-doped superlattices　　　　　　　　　　　　　　　
  Yagi, S.; Noguchi, S.; Hijikata, Y.; Kuboya, S.; Onabe, K.; Okada, Y.; Yaguchi, H.
  Applied Physics Express, Volume：7, Number：10, 2014, [Reviewed]
  The photoabsorption characteristics of GaAs:N delta-doped superlattices (SLs) are investigated. Periodic insertion of N delta-doped induces the formation of conduction subbands E+ and E-, and each conduction subband forms SL minibands with the GaAs between the delta-doped layers. In addition to an optical absorption related to the E- band, an abrupt absorption edge originating transition between the valence band and an E+-related miniband is observed at 1.6 eV in a photoluminescence excitation indicating that GaAs:N delta-doped SLs are promising candidates for the absorber of intermediate-band solar cells. (C) 2014 The Japan Society of Applied Physics
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.7567/APEX.7.102301
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84988891884&origin=inward
  DOI ID：10.7567/APEX.7.102301, ISSN：1882-0778, eISSN：1882-0786, ORCID：69201953, SCOPUS ID：84988891884, Web of Science ID：WOS:000344439300007
• Thermal Oxidation Mechanism of Silicon Carbide　　　　　　　　　　　　　　　
  Hijikata, Yasuto; Yagi, Shuhei; Yaguchi, Hiroyuki; Sadafumi, Yoshida
  Physics and Technology of Silicon Carbide Devices, First page：26, Last page：26, 2013, [Reviewed]
  DOI：https://doi.org/10.5772/50748
  DOI ID：10.5772/50748, ORCID：31489793
• Physics and Technology of Silicon Carbide Devices　　　　　　　　　　　　　　　
  Hijikata, Yasuto
  2013, [Reviewed]
  DOI：https://doi.org/10.5772/3428
  DOI ID：10.5772/3428, ORCID：31489790
• Nondestructive and Contactless Characterization Method for Spatial Mapping of the Thickness and Electrical Properties in Homo-Epitaxially Grown SiC Epilayers Using Infrared Reflectance Spectroscopy　　　　　　　　　　　　　　　
  Yoshida, Sadafumi; Hijikata, Yasuto; Yaguchi, Hiroyuki
  Physics and Technology of Silicon Carbide Devices, First page：26, Last page：26, 2013, [Reviewed]
  DOI：https://doi.org/10.5772/50749
  DOI ID：10.5772/50749, ORCID：31489788
• RF-MBE growth of cubic InN nano-scale dots on cubic GaN　　　　　　　　　　　　　　　
  Suzuki, J.; Orihara, M.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
  Journal of Crystal Growth, Volume：378, First page：454, Last page：458, 2013, [Reviewed]
  This paper reports the first successful growth and structural control of cubic InN (c-InN) nano-scale dots. The samples were grown on MgO (0 0 1) substrates by RF-N-2 plasma molecular beam epitaxy (RF-MBE). Cubic GaN (c-GaN) underlayers with a thickness of 500 nm were grown on the substrates followed by the growth of a few nm-thick InN under various conditions. The formation of InN dots aligned along the < 1 1 0 > directions were confirmed by atomic force microscopy (AFM). X-ray diffraction (XRD) measurements suggested the cubic zincblende lattice structure of the obtained InN dots. The area density and size of c-InN dots were well controlled by adjusting the growth conditions such as the substrate temperature and the In flux, and a very high dot density of 2.2 x 10(11) cm(-2) was successfully obtained at a growth temperature of 470 degrees C and an In flux of 7.0 x 10(-5) Pa. (c) 2013 Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.050
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84885434999&origin=inward
  DOI ID：10.1016/j.jcrysgro.2012.12.050, ISSN：0022-0248, eISSN：1873-5002, ORCID：69201985, SCOPUS ID：84885434999, Web of Science ID：WOS:000323355900113
• Optical Absorption by E+ Miniband of GaAs:N delta-Doped Superlattices　　　　　　　　　　　　　　　
  Shuhei Yagi; Shunsuke Noguchi; Yasuto Hijikata; Shigeyuki Kuboya; Kentaro Onabe; Yoshitaka Okada; Hiroyuki Yaguchi
  2013 IEEE 39TH PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC), First page：2490, Last page：2493, 2013, [Reviewed]
  The optical properties of GaAs:N delta-doped superlattices (SLs) are investigated by photoreflectance (PR), photo luminescence (PL) and photoluminescence excitation (PLE) spectroscopy. A direct evidence of the optical absorption due to an E, related band of a GaAs:N delta-doped SLs is indicated as a clear absorption edge at 1.6 eV by PLE. AlGaAs layers fabricated on the both sides of the SL region exclude the effect of GaAs absorption on the PLE spectrum, resulting in the successful detection of the absorption property of the SL. In addition, some preliminary characterization of a solar cell using a GaAs:N delta-doped SL is shown. The photocarrier generation originating from SL miniband absorption is confirmed by quantum efficiency measurements.
  IEEE, English, International conference proceedings
  DOI：https://doi.org/10.1109/PVSC.2013.6744981
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84896474240&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84896474240&origin=inward
  DOI ID：10.1109/PVSC.2013.6744981, ISSN：0160-8371, ORCID：30384768, SCOPUS ID：84896474240, Web of Science ID：WOS:000340054100565
• Molecular beam epitaxy of ErGaAs alloys on GaAs (0 0 1) substrates　　　　　　　　　　　　　　　
  Jin, R.G.; Yagi, S.; Hijikata, Y.; Kuboya, S.; Onabe, K.; Katayama, R.; Yaguchi, H.
  Journal of Crystal Growth, Volume：378, First page：85, Last page：87, 2013, [Reviewed]
  We have successfully grown high crystalline quality ErGaAs alloy layers by solid-source molecular beam epitaxy. The X-ray diffraction (XRD) peak of ErGaAs alloys was found to shift systematically from the GaAs peak with increasing Er concentration up to 3.7%. XRD (1 1 5) reciprocal space map measurements revealed that the ErGaAs epitaxial layer is coherently grown on GaAs. We found from XRD results that ErGaAs alloys with low Er concentrations tend to crystallize in the zincblende structure. (c) 2012 Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/j.jcrysgro.2012.12.043
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84885427998&origin=inward
  DOI ID：10.1016/j.jcrysgro.2012.12.043, ISSN：0022-0248, ORCID：69201995, SCOPUS ID：84885427998, Web of Science ID：WOS:000323355900023
• Model calculations of SiC oxide growth rates at sub-atmospheric pressures using the Si and c emission model　　　　　　　　　　　　　　　
  Hijikata, Y.; Yagi, S.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：740-742, First page：833, Last page：+, 2013, [Reviewed]
  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.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.740-742.833
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84874076989&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.740-742.833, ISSN：0255-5476, ORCID：69201937, SCOPUS ID：84874076989, Web of Science ID：WOS:000319785500198
• Biexciton Emission from Single Isoelectronic Traps Formed by Nitrogen-Nitrogen Pairs in GaAs　　　　　　　　　　　　　　　
  Takamiya, Kengo; Fukushima, Toshiyuki; Yagi, Shuhei; Hijikata, Yasuto; Mochizuki, Toshimitsu; Yoshita, Masahiro; Akiyama, Hidefumi; Kuboya, Shigeyuki; Onabe, Kentaro; Katayama, Ryuji; Yaguchi, Hiroyuki; Ihn, T; Rossler, C; Kozikov, A
  Physics of Semiconductors, Volume：1566, Number：1, First page：538, Last page：+, 2013, [Reviewed]
  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.
  AMER INST PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1063/1.4848523
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84907305933&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84907305933&origin=inward
  DOI ID：10.1063/1.4848523, ISSN：0094-243X, eISSN：1551-7616, ORCID：31489784, SCOPUS ID：84907305933, Web of Science ID：WOS:000331793000268
• Stacked structure of self-organized cubic InN nano-dots grown by molecular beam epitaxy　　　　　　　　　　　　　　　
  Yagi, S.; Suzuki, J.; Orihara, M.; Hijikata, Y.; Yaguchi, H.
  Physica Status Solidi (C) Current Topics in Solid State Physics, Volume：10, Number：11, First page：1545, Last page：1548, 2013, [Reviewed]
  A two-stacked cubic (c-) InN/c-GaN nano-scale dot structure is fabricated on a MgO(001) substrate by RF-N-2 molecular beam epitaxy and its microstructures are investigated by scanning transmission electron microscopy (STEM). The cubic lattice structure of InN dots is verified by STEM observations. It is implied that c-InN dots formed on a smooth c-GaN surface have the {111} facets. The c-GaN cap layer has an uneven surface, which reflects the shape of the c-InN dots embedded beneath the cap layer. InN selectively deposits in concave regions on the c-GaN cap layer, which appear above in-between positions of embedded dots. Thus, stacked c-InN/c-GaN dots do not tend to align vertically. These results open the possibility for multi-stacking structures of c-InN dots and their application to high-performance optoelectronic devices based on the nitride semiconductors. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssc.201300275
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84887619549&origin=inward
  DOI ID：10.1002/pssc.201300275, ISSN：1862-6351, eISSN：1610-1642, ORCID：69201928, SCOPUS ID：84887619549, Web of Science ID：WOS:000334583400049
• Conversion efficiency of intermediate band solar cells with GaAs:Nλ-doped superlattices　　　　　　　　　　　　　　　
  Yagi, S.; Noguchi, S.; Hijikata, Y.; Kuboya, S.; Onabe, K.; Yaguchi, H.
  Japanese Journal of Applied Physics, Volume：52, Number：10 PART1, 2013, [Reviewed]
  The performance of intermediate band solar cells using a GaAs:N delta-doped superlattice (SL) as the optical absorber is analyzed. In GaAs: N delta-doped SLs, both of the E+ and E- bands formed around the N delta-doped layers form SL potentials with the conduction band of the spacer GaAs layers, resulting in the formation of multiple minibands. The conversion efficiency limits of the solar cells are calculated using the detailed balance model based on intermediate band structures composed of the valence band and two minibands formed respectively in the E-- and E+-related SL potentials. A high efficiency of 62.6% for full concentration is expected by properly adjusting the structural parameters of the SL. Alloying other elements such as In to a GaAs:N delta-doped SL is a possible way to further facilitate the development of intermediate band materials for high-efficiency solar cells. (C) 2013 The Japan Society of Applied Physics
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.7567/JJAP.52.102302
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84887232116&origin=inward
  DOI ID：10.7567/JJAP.52.102302, ISSN：0021-4922, eISSN：1347-4065, ORCID：69201966, SCOPUS ID：84887232116, Web of Science ID：WOS:000325209000024
• Analysis of electronic structures of nitrogen δ-doped GaAs superlattices for high efficiency intermediate band solar cells　　　　　　　　　　　　　　　
  Noguchi, S.; Yagi, S.; Sato, D.; Hijikata, Y.; Onabe, K.; Kuboya, S.; Yaguchi, H.
  IEEE Journal of Photovoltaics, Volume：3, Number：4, First page：1287, Last page：1291, 2013, [Reviewed]
  Nitrogen delta-doped GaAs superlattices (SLs) were fabricated, and their energy structures were investigated. A number of strong transition signals are observed in photoreflectane (PR) spectra in an energy range from 1.54 to 1.78 eV for SL samples in which any transitions are not observed in uniformly nitrogen-doped GaAsN with comparable nitrogen content. Both of the E+ and E- bands formed around the nitrogen delta-doped layers compose SL potentials with the conduction band of the spacer GaAs layers, resulting in the formation of multiple minibands. The energy range of the SL minibands well explains the observed transition energies in the PR spectra. The PR signal intensity ratios of the E+-related transitions to the E--related transitions for the SLs are notably large compared with those usually observed for conventional GaAsN alloys. This enhancement of electron transition associated with the E+-related bands should be advantageous as intermediate band material. Therefore, nitrogen delta-doped GaAs SLs are expected to be an excellent alternative to uniformly doped GaAsN alloys for the use in intermediate band solar cells.
  IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, English, Scientific journal
  DOI：https://doi.org/10.1109/JPHOTOV.2013.2271978
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84884672481&origin=inward
  DOI ID：10.1109/JPHOTOV.2013.2271978, ISSN：2156-3381, eISSN：2156-3403, ORCID：69201943, SCOPUS ID：84884672481, Web of Science ID：WOS:000324881400023
• Single photon generation from nitrogen atomic-layer doped gallium arsenide　　　　　　　　　　　　　　　
  Takamiya, K.; Endo, Y.; Fukushima, T.; Yagi, S.; Hijikata, Y.; Mochizuki, T.; Yoshita, M.; Akiyama, H.; Kuboya, S.; Onabe, K.; Katayama, R.; Yaguchi, H.
  Materials Science Forum, Volume：706-709, First page：2916, Last page：+, 2012, [Reviewed]
  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.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.706-709.2916
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84856180201&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.706-709.2916, ISSN：0255-5476, ORCID：69201935, SCOPUS ID：84856180201, Web of Science ID：WOS:000308517301220
• RF-MBE growth of semipolar InN(10-13) and InGaN(10-13) on GaAs(110)　　　　　　　　　　　　　　　
  Orihara, M.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
  Physica Status Solidi (C) Current Topics in Solid State Physics, Volume：9, Number：3-4, First page：658, Last page：661, 2012, [Reviewed]
  We have studied InN and InGaN films grown on GaAs(110) substrates by RF-assisted molecular beam epitaxy. Reflection high-energy diffraction observation and X-ray diffraction (XRD) measurements revealed that the InN films were epitaxially grown with InN(10-13)//GaAs(110). From XRD pole figure measurements, only one InN(0002) peak was found at an angle of 31.8 degrees from the pole, indicating that the semipolar InN films were free from twin crystals. This can be explained by the similarity in the anisotropic structure between InN(10-13) and GaAs(110) surfaces. By using low-temperature InN buffer layers, we could obtain semipolar InN films with a smooth surface. Polarization anisotropy in the photoluminescence peak observed at 0.67 eV from semipolar InN(10-13) was weaker than that from alpha-plane InN, which is reasonable considering the smaller angle between the c-axis and the perpendicular direction to the semipolar InN surface. We have also successfully grown In-rich InGaN(10-13) on GaAs(110) substrates with an InN(10-13) intermediate layer, and observed strong photoluminescence from the semipolar InGaN films. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssc.201100365
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84858842029&origin=inward
  DOI ID：10.1002/pssc.201100365, ISSN：1862-6351, eISSN：1610-1642, ORCID：69201984, SCOPUS ID：84858842029, Web of Science ID：WOS:000306521600059
• Oxygen partial pressure dependence of the SiC oxidation process studied by in-situ spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Kouda, K.; Hijikata, Y.; Yagi, S.; Yaguchi, H.; Yoshida, S.
  Journal of Applied Physics, Volume：112, Number：2, First page：6, 2012, [Reviewed]
  The oxygen partial pressure dependence of the Silicon carbide (SiC) oxidation process was investigated using in-situ spectroscopic ellipsometry at oxygen partial pressures between 1 and 0.02 atm for 4H-SiC (0001) Si-and (000-1) C-faces. Analyses of the interface structure between the oxide and SiC indicate that the interface layer has a modified SiC-like structure around 1 nm thick accompanied by oxide growth; the structure and thickness do not change after an oxide growth of about 7 nm. The oxide thickness dependence of the growth rate at sub-atmospheric oxygen pressures is similar to that at 1 atm pressure, that is, just after oxidation starts, the growth rate rapidly decreases as the oxidation proceeds. After an oxide growth of about 7 nm thick, the deceleration of the growth rate suddenly changes to a gentle slope. The thickness at which deceleration changes depends slightly on both the oxygen partial pressure and surface polarity of the SiC substrate. The origins of these two deceleration stages, i.e., rapid and gentle decelerations, are discussed from their pressure dependencies based on the SiC oxidation model taking into account the interfacial emission of Si and C atoms. The formation and structures of the interface layers are also discussed in relation to the oxidation mechanisms. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4736801]
  AMER INST PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1063/1.4736801
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84865484968&origin=inward
  DOI ID：10.1063/1.4736801, ISSN：0021-8979, eISSN：1089-7550, ORCID：69201996, SCOPUS ID：84865484968, Web of Science ID：WOS:000308424500114
• Micro-photoluminescence study on the influence of oxidation on stacking faults in 4H-SiC epilayers　　　　　　　　　　　　　　　
  Yamagata, H.; Yagi, S.; Hijikata, Y.; Yaguchi, H.
  Applied Physics Express, Volume：5, Number：5, First page：3, 2012, [Reviewed]
  We have investigated the influence of thermal oxidation on stacking faults (SFs) in 4H-SiC epilayers by performing micro-photoluminescence measurements for 4H-SiC substrates before and after thermal oxidation. We found that SF (emission wavelength: similar to 425.5 nm) thought to be a single Shockley stacking fault was expanded by thermal oxidation. In addition, as a result of comparison between before and after Ar annealing, the SF was not extended after Ar annealing. We also found that only the SFs extended by laser irradiation is eliminated by oxidation. (c) 2012 The Japan Society of Applied Physics
  JAPAN SOC APPLIED PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1143/APEX.5.051302
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84861398046&origin=inward
  DOI ID：10.1143/APEX.5.051302, ISSN：1882-0778, eISSN：1882-0786, ORCID：69201942, SCOPUS ID：84861398046, Web of Science ID：WOS:000303932500005
• Biexciton luminescence from individual isoelectronic traps in nitrogen δ-doped GaAs　　　　　　　　　　　　　　　
  Takamiya, K.; Fukushima, T.; Yagi, S.; Hijikata, Y.; Mochizuki, T.; Yoshita, M.; Akiyama, H.; Kuboya, S.; Onabe, K.; Katayama, R.; Yaguchi, H.
  Applied Physics Express, Volume：5, Number：11, First page：3, 2012, [Reviewed]
  We report on the observation of biexciton luminescence from single isoelectronic traps formed by nitrogen-nitrogen pairs in nitrogen delta-doped GaAs. The biexciton luminescence intensity showed a quadratic dependence on the excitation power while the exciton luminescence intensity increased linearly with increasing excitation power. The biexciton binding energy was found to be 8 meV, which is considerably larger than that reported for single InAs quantum dots in GaAs. We have also found that both the biexciton and exciton emission lines show completely unpolarized and no fine-structure splitting. This is suitable for the application to polarization-entangled photon pairs. (C) 2012 The Japan Society of Applied Physics
  IOP PUBLISHING LTD, English, Scientific journal
  DOI：https://doi.org/10.1143/APEX.5.111201
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84869186070&origin=inward
  DOI ID：10.1143/APEX.5.111201, ISSN：1882-0778, eISSN：1882-0786, ORCID：69201990, SCOPUS ID：84869186070, Web of Science ID：WOS:000310867800003
• Analysis of the Energy Structure of Nitrogen delta-Doped GaAs Superlattices for High Efficiency Intermediate Band Solar Cells　　　　　　　　　　　　　　　
  Shunsuke Noguchi; Shuhei Yagi; Yasuto Hijikata; Kentaro Onabe; Shigeyuki Kuboya; Hiroyuki Yaguchi
  2012 38TH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE (PVSC), First page：83, Last page：86, 2012, [Reviewed]
  Nitrogen delta-doped GaAs superlattices were fabricated and their energy structures were investigated. Several transitions related to E+ band of nitrogen delta-doped regions were observed in photoreflectance ( PR) spectra at energies ranging 1.5-1.7 eV for the superlattices at which no transitions were observed for uniformly doped GaAsN. The PR signal intensity of E+ related band transitions is significantly higher than those observed in uniformly doped GaAsN. This enhancement of E+ related band transitions is advantageous as an intermediate band material, and thus, nitrogen delta-doped GaAs superlattice structures are expected to be an excellent alternative for the use of intermediate band solar cells.
  IEEE, English, International conference proceedings
  DOI：https://doi.org/10.1109/PVSC.2012.6317573
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84869429937&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84869429937&origin=inward
  DOI ID：10.1109/PVSC.2012.6317573, ISSN：0160-8371, ORCID：30384773, SCOPUS ID：84869429937, Web of Science ID：WOS:000309917800019
• Quantum well double barrier resonant tunneling structures for selective contacts of hot carrier solar cells　　　　　　　　　　　　　　　
  Shuhei Yagi; Yasuto Hijikata; Yoshitaka Okada; Hiroyuki Yaguchi
  Conference Record of the IEEE Photovoltaic Specialists Conference, First page：003309, Last page：003312, 2011, [Reviewed]
  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.
  International conference proceedings
  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
• Theoretical studies for Si and C emission into SiC layer during oxidation　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：679-680, First page：429, Last page：+, 2011, [Reviewed]
  To understand the structure of SiC-oxide interface more in detail, we propose a profiling theory of Si and C emission into SiC layer during oxidation. Simulations of the depth profiles of Si and C interstitials results in the structures analogous with those observed from a spectroscopic ellipsometry. To determine the diffusivities of Si and C interstitials, we performed capacitance-voltage measurements for examining the re-distribution profiles of nitrogen after oxidation and compared between observed and calculated profile. The calculated nitrogen profiles showed good fits to the observed ones in the case of self-diffusivity of C interstitials magnified by several 10 times for literature value. Finally, we discuss the validity of the proposed theory.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.679-680.429
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=79955121573&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.679-680.429, ISSN：0255-5476, ORCID：69201986, SCOPUS ID：79955121573, Web of Science ID：WOS:000291673500102
• High Cubic-Phase Purity InN on MgO (001) Using Cubic-Phase GaN as a Buffer Layer　　　　　　　　　　　　　　　
  Sanorpim, S.; Kuntharin, S.; Parinyataramas, J.; Yaguchi, H.; Iwahashi, Y.; Orihara, M.; Hijikata, Y.; Yoshida, S.; Ihm, J; Cheong, H
  Physics of Semiconductors: 30th International Conference on the Physics of Semiconductors, Volume：1399, First page：131, Last page：132, 2011, [Reviewed]
  High cubic-phase purity InN films were grown on MgO (001) substrates by molecular beam epitaxy with a cubic-phase GaN buffer layer. The cubic phase purity of the InN grown layers has been analyzed by high resolution X-ray diffraction, μ-Raman scattering and transmission electron microscopy. It is evidenced that the hexagonal-phase content in the InN overlayer much depends on hexagonal-phase content in the cubic-phase GaN buffer layer and increases with increasing the hexagonal-phase GaN content. From Raman scattering measurements, in addition, the InN layer with lowest hexagonal component (6%), only Raman characteristics of cubic TO InN and LO InN modes were observed, indicating a formation of a small amount of stacking faults, which does not affect on vibrational property. © 2011 American Institute of Physics.
  AMER INST PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1063/1.3666291
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84855479154&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84855479154&origin=inward
  DOI ID：10.1063/1.3666291, ISSN：0094-243X, eISSN：1551-7616, ORCID：31489802, SCOPUS ID：84855479154, Web of Science ID：WOS:000301053000053
• Growth Rate Enhancement of Silicon-Carbide Oxidation in Thin Oxide Regime
  Hijikata, Yasuto; Yaguchi, Hiroyuki; Yoshida, Sadafumi
  Properties and Applications of Silicon Carbide, First page：77, Last page：87, 2011, [Reviewed]
  DOI：https://doi.org/10.5772/14591
  DOI ID：10.5772/14591, ORCID：31489800
• RF-MBE growth of InN on 4H-SiC (0001) with off-angles　　　　　　　　　　　　　　　
  Orihara, M.; Takizawa, S.; Sato, T.; Ishida, Y.; Yoshida, S.; Hijikata, Y.; Yaguchi, H.
  Physica Status Solidi (C) Current Topics in Solid State Physics, Volume：7, Number：7-8, First page：2016, Last page：2018, 2010, [Reviewed]
  We have grown InN on 4H-SiC (0001) substrates with various off-angles by RF-N-2 plasma molecular beam epitaxy (RF-MBE). Scanning electron microscope observation revealed that InN films grown on 4H-SiC (0001) substrates with off-angles of 4 degrees and 8 degrees are very smooth and that there are no voids which have often observed for InN epitaxial layers. X-ray diffraction reciprocal space maps for InN grown on 4H-SiC (0001) showed that the c-axes of InN grown on 4H-SiC 4 degrees and 8 degrees off substrates are inclined by 0.35 degrees and 0.8 degrees, respectively, toward the misorientation of the substrate while the c-axis of InN is parallel to that of 4H-SiC for the on-axis substrate. Strong PL peak was observed from InN grown on 4 degrees off substrate at 0.68 eV at 15 K. The PL peak was clearly observed even at room temperature and simply shifted to lower energies with increasing temperature. The difference in the PL peak energy between at 15 K and 300 K was 20 meV, which is reasonable taking into account the difference in the thermal coefficients of InN and SiC. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssc.200983441
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=77955823769&origin=inward
  DOI ID：10.1002/pssc.200983441, ISSN：1862-6351, eISSN：1610-1642, ORCID：69201933, SCOPUS ID：77955823769, Web of Science ID：WOS:000301587600083
• Photoluminescence from single isoelectronic traps in nitrogen delta-doped GaAs grown on GaAs(1 1 1)A　　　　　　　　　　　　　　　
  Fukushima, T.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Okano, M.; Yoshita, M.; Akiyama, H.; Kuboya, S.; Katayama, R.; Onabe, K.
  Physica E: Low-Dimensional Systems and Nanostructures, Volume：42, Number：10, First page：2529, Last page：2531, 2010, [Reviewed]
  We have studied photoluminescence (PL) observed from single isoelectronic traps formed by nitrogen pairs in nitrogen δ-doped GaAs layers grown on GaAs(1 1 1)A substrates. The PL was composed of a single peak with a narrow linewidth of ∼80 μeV. Polarized PL measurements confirmed that the emission from single isoelectronic traps in nitrogen δ-doped GaAs(1 1 1) is unpolarized irrespective of nitrogen pair arrangements. These results can be explained by in-plane isotropy of the samples, which is consistent with the symmetrical property of GaAs(1 1 1), and demonstrate that utilizing (1 1 1) substrate is an effective means for obtaining unpolarized single photons, which are desirable for the application to quantum cryptography. © 2009 Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/j.physe.2009.12.011
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=77958003985&origin=inward
  DOI ID：10.1016/j.physe.2009.12.011, ISSN：1386-9477, eISSN：1873-1759, ORCID：69201954, SCOPUS ID：77958003985, Web of Science ID：WOS:000284723200013
• In-situ spectroscopic ellipsometry study of SiC oxidation at low oxygen-partial-pressures　　　　　　　　　　　　　　　
  Kouda, K.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：645-648, First page：813, Last page：816, 2010, [Reviewed]
  We have investigated the oxidation process of SiC (000-1) C-face at low oxygen partial pressures using an in-situ spectroscopic ellipsometry. The oxide growth rate decreased steeply at the early stage of oxidation and then slowly decreased with increasing oxide thickness. The initial oxide growth rate was almost proportional to the oxygen partial pressure for both the polar directions. This result suggests that the initial interfacial reaction rate is constant regardless of the concentration of oxidants reaching the interface. © (2010) Trans Tech Publications, Switzerland.
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.645-648.813
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=77955437802&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.645-648.813, ISSN：0255-5476, eISSN：1662-9752, ORCID：69201930, SCOPUS ID：77955437802, Web of Science ID：WOS:000279657600193
• Model calculations of SiC oxide growth rate at various oxidation temperatures based on the silicon and carbon emission model　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：645-648, First page：809, Last page：+, 2010, [Reviewed]
  We have tried to apply the oxidation model of SIC proposed previously, termed 'Si-C emission model', to the oxide growth rate at various oxidation temperatures. We have found that the model well reproduces the oxide thickness dependences of oxide growth rates for all of the temperatures measured for both of the SiC Si- and C-faces. We have estimated the temperature dependence of oxide depth profiles of Si and C interstitials by using the Si-C emission model, and discussed the structure at/near the SIC-oxide interface.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.645-648.809
  DOI ID：10.4028/www.scientific.net/MSF.645-648.809, ISSN：0255-5476, ORCID：69201949, SCOPUS ID：77955456281, Web of Science ID：WOS:000279657600192
• Model calculation of SiC oxidation rates in the thin oxide regime　　　　　　　　　　　　　　　
  Hijikata, Y.; Yamamoto, T.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：600-603, First page：663, Last page：666, 2009, [Reviewed]
  To explain the growth rate enhancement of SiC oxidation in the thin oxide regime, which was recently found from the real time monitoring experiments of the initial oxidation stage of SiC (000-1) C-face using an in-situ spectroscopic ellipsometer, we tried to apply the interfacial Si emission model, which has been originally proposed for Si oxidation, and found that the Si emission model successfully reproduced the SiC oxidation rates at the whole range of oxide thickness and at oxidation temperatures measured. By comparing with the simulations for Si oxidation, we have discussed the oxidation mechanism of SiC.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/3-908453-11-9.663
  DOI ID：10.4028/3-908453-11-9.663, ISSN：0255-5476, ORCID：69201962, SCOPUS ID：60349102034, Web of Science ID：WOS:000263555300158
• Model calculation of SiC oxide growth rate based on the silicon and carbon emission model　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：615 617, First page：489, Last page：492, 2009, [Reviewed]
  We proposed a kinetic model For SiC oxidation, named 'silicon and carbon (Si-C) emission model', taking into account the emission of Si and C atoms from the SiC-oxide interface, which suppresses the oxidation rate at the interface. Based oil the model, we calculated oxide growth rates for SiC (0001) Si- and (000-1) C-face and found that the calculated values exhibit good fits to the measured ones in the entire oxide thickness range for both faces. We also calculated depth profiles of Si and C interstitials and oxidants, and discussed the oxidation mechanism of SiC as well as the difference in the oxidation process of Si-face and C-face.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.615-617.489
  DOI ID：10.4028/www.scientific.net/MSF.615-617.489, ISSN：0255-5476, ORCID：47642249, SCOPUS ID：67650452007, Web of Science ID：WOS:000265961100117
• Observation of SiC oxidation in ultra-thin oxide regime by in-situ spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Takaku, T.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：615 617, First page：509, Last page：512, 2009, [Reviewed]
  Thermal oxidation process of silicon carbide in ultra-thin oxide regime has been Studied by performing in-situ and real time spectroscopic ellipsometry. We found the thermal oxidation at 700 degrees C forms no or extremely thin interface layers between SiC and oxide layers. In contrast, the oxidation at 850 degrees C forms all interface layer of around 1 nm in thickness, having similar thickness and optical constants of the interface layers formed by the oxidation at higher temperature than 1000 degrees C. To make clear the conditions no interface layer is formed, i.e., whether low temperature growth or thin oxide thickness is crucial, we have performed the oxidation at 850 degrees C in the reduced oxygen pressure. Based on the results of these experiments, we discussed the origin of the formation of interface layers as well as the oxidation mechanism of SiC.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.615-617.509
  DOI ID：10.4028/www.scientific.net/MSF.615-617.509, ISSN：0255-5476, ORCID：47642242, SCOPUS ID：77955444151, Web of Science ID：WOS:000265961100122
• Oxygen-partial-pressure dependence of SiC oxidation rate studied by in-situ spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Yamamoto, T.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：600-603, First page：667, Last page：670, 2009, [Reviewed]
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/3-908453-11-9.667
  DOI ID：10.4028/3-908453-11-9.667, ISSN：0255-5476, ORCID：47642244, SCOPUS ID：60349127717, Web of Science ID：WOS:000263555300159
• Characterization of 4H-SiC-SiO2 interfaces by a deep ultraviolet spectroscopic ellipsometer　　　　　　　　　　　　　　　
  Sekia, H.; Wakabayashib, T.; Hijikatac, Y.; Yaguchid, H.; Yoshidae, S.
  Materials Science Forum, Volume：615 617, First page：505, Last page：508, 2009, [Reviewed]
  We have characterized 4H-SiC-oxide interfaces fabricated by thermal oxidation of SiC using spectroscopic ellipsometry in the wide spectral range from visible to deep UV region. It was found that there exists an interface layer, around 1 nm in thickness, regardless of the oxide thickness from 15 nm to 40 nm. The optical constants of the interface layer have similar spectral dependence to those of SiC, though the absolute value of the refractive indices is 0.5-1 larger than that of SiC. We have discussed the structure of the interface layer based oil the oxidation mechanism of SiC, like the Si-emission model.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.615-617.505
  DOI ID：10.4028/www.scientific.net/MSF.615-617.505, ISSN：0255-5476, ORCID：69201944, SCOPUS ID：67650428139, Web of Science ID：WOS:000265961100121
• Optical and electrical characterizations of 4H-SiC-oxide interfaces by spectroscopic ellipsometry and capacitance-voltage measurements　　　　　　　　　　　　　　　
  Hashimoto, H.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Applied Surface Science, Volume：255, Number：20, First page：8648, Last page：8653, 2009, [Reviewed]
  4H-SiC-oxide interfaces formed by various oxidation methods on SiC (0 0 0 1) Si-and (0 0 0 (1) over bar) C-face substrates have been characterized by performing spectroscopic ellipsometry in wide spectral region including deep UV spectral range and capacitance-voltage measurements. The results exhibit that the refractive indices of the interface layers well correlate with interface state density in all the cases of oxidation processes. To investigate the difference in interface characteristics between wet and dry oxidation, we compared to the sample fabricated by wet oxidation followed by heating in Ar or O-2 atmosphere, aiming to remove hydrogen related species at the interface. We also tried to make clear the difference in the interface characteristics between Si-and C-faces by lowering the oxidation rate of C-face down to those for Si-face. Putting together with all of the results obtained, we discuss the origins that determine the interface characteristics in terms of both the optical and electrical characterizations. (C) 2009 Elsevier B. V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/j.apsusc.2009.06.058
  DOI ID：10.1016/j.apsusc.2009.06.058, ISSN：0169-4332, eISSN：1873-5584, ORCID：69201940, SCOPUS ID：67650503177, Web of Science ID：WOS:000268123800057
• A kinetic model of silicon carbide oxidation based on the interfacial silicon and carbon emission phenomenon　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Applied Physics Express, Volume：2, Number：2, First page：021203, 2009, [Reviewed]
  We proposed a kinetic model for thermal oxidation of silicon carbide, termed "silicon and carbon emission model", taking into account the Si and C emissions from the oxidation interface, which lead to a reduction of interfacial reaction rate. We used this model to calculate oxide growth rates and found that the derived growth rates showed a good fit with the measured rates over the entire oxide thickness for both the C and Si faces. We discussed the difference in oxidation mechanism between these polar faces in terms of the difference in parameter values deduced from the curve fits. (C) 2009 The Japan Society of Applied Physics
  JAPAN SOCIETY APPLIED PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1143/APEX.2.021203
  DOI ID：10.1143/APEX.2.021203, ISSN：1882-0778, ORCID：69201987, SCOPUS ID：60349083681, Web of Science ID：WOS:000264942800007
• Photoluminescence study of hexagonal InN/InGaN quantum well structures grown on 3C-SiC (001) substrates by molecular beam epitaxy　　　　　　　　　　　　　　　
  Hirano, S.; Inoue, T.; Shikata, G.; Orihara, M.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Hirabayashi, Y.
  Physica Status Solidi (C) Current Topics in Solid State Physics, Volume：5, Number：6, First page：1730, Last page：1732, 2008, [Reviewed]
  We have studied photoluminescence from hexagonal InN/InGaN multiple quantum well structures grown on 3C-SiC (001) substrates with an InGaN underlayer by plasma assisted molecular beam epitaxy. We have observed photoluminescence spectra of InN/InGaN MQWs with various well widths. The photoluminescence peak related to quantum wells was clearly observed even at room temperature and found to shift to higher energies with decreasing well width due to the quantum confinement effect. We also discuss the effect of the built-in electric fields on the PL peak energy. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
  Scientific journal
  DOI：https://doi.org/10.1002/pssc.200778606
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=77951210969&origin=inward
  DOI ID：10.1002/pssc.200778606, ISSN：1862-6351, eISSN：1610-1642, ORCID：69201945, SCOPUS ID：77951210969, Web of Science ID：WOS:000256695700075
• Improvement of the surface morphology of a-plane InN using low-temperature InN buffer layers　　　　　　　　　　　　　　　
  Shikata, G.; Hirano, S.; Inoue, T.; Orihara, M.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Physica Status Solidi (C) Current Topics in Solid State Physics, Volume：5, Number：6, First page：1808, Last page：1810, 2008, [Reviewed]
  We report on the improvement of the surface morphology of a-plane InN films grown by RF molecular beam epitaxy. By using low-temperature (LT) InN buffer layers, we could successfully obtain InN films with a smooth surface, The full width at half maximum values of the x-ray diffraction (11-20) rocking curve along the [0001] InN direction were 2870 arcsec and 3410 arcsec for a-plane InN samples grown at 500 degrees C with and without LT-InN buffer layers, respectively. Thus, we-could improve also the crystalline quality of a-plane InN films by using LT-InN buffer layers. We observed strong polarization anisotropy in the photoluminescence spectra of a-plane InN, which is typical of nonpolar wurtzite III-nitride films.
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssc.200778662
  DOI ID：10.1002/pssc.200778662, ISSN：1862-6351, ORCID：69201977, SCOPUS ID：75749134181, Web of Science ID：WOS:000256695700100
• Photoluminescence of cubic InN films on MgO (001) substrates　　　　　　　　　　　　　　　
  Inoue, T.; Iwahashi, Y.; Oishi, S.; Orihara, M.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Physica Status Solidi (C) Current Topics in Solid State Physics, Volume：5, Number：6, First page：1579, Last page：1581, 2008, [Reviewed]
  We have studied photoluminescence from cubic InN films grown on MgO substrates with a cubic GaN underlayer by RF N(2) plasma molecular beam epitaxy. A single PL peak was observed at 0.47 eV. By analyzing the reflectance spectra of cubic InN films, we could derive the refractive index and extinction coefficient, and found the band gap energy of cubic InN is 0.48 eV, indicating that the PL peak observed at 0.47 eV is due to the interband transition of cubic InN. The difference in the PL peak energy between hexagonal and cubic InN is in good agreement with that predicted by ab-initio calculations.
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssc.200778505
  DOI ID：10.1002/pssc.200778505, ISSN：1862-6351, ORCID：69201982, SCOPUS ID：65249177185, Web of Science ID：WOS:000256695700031
• Twin photoluminescence peaks from single isoelectronic traps in nitrogen δ-doped GaAs　　　　　　　　　　　　　　　
  Endo, Y.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Yoshita, M.; Akiyama, H.; Nakajima, F.; Katayama, R.; Onabe, K.
  Physica E: Low-Dimensional Systems and Nanostructures, Volume：40, Number：6, First page：2110, Last page：2112, 2008, [Reviewed]
  We report on twin emission peaks observed from single isoelectronic traps formed by nitrogen pairs in nitrogen δ-doped GaAs by high-energy resolution micro-photoluminescence (PL) spectroscopy. The twin PL peaks show almost the same intensity with narrow linewidths of 20-50 μeV, which are considerably smaller than that ever reported for isoelectronic traps in GaAs:N. The higher and lower energy luminescence transitions were linearly polarized in the [1 1̄ 0] and [1 1 0] directions, respectively, indicating that the two exciton states have completely orthogonal relations with each other. The fact that any pair of the twin PL peaks has the same polarization properties suggests that the splitting is due to the anisotropy between [1 1̄ 0] and [1 1 0] directions in the host crystal and is possibly explained by the strain anisotropy in the sample. © 2007 Elsevier B.V. All rights reserved.
  Scientific journal
  DOI：https://doi.org/10.1016/j.physe.2007.10.047
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=41349112928&origin=inward
  DOI ID：10.1016/j.physe.2007.10.047, ISSN：1386-9477, ORCID：69201991, SCOPUS ID：41349112928, Web of Science ID：WOS:000255717400104
• Oxide growth rate enhancement of silicon carbide (0001) Si-faces in thin oxide regime　　　　　　　　　　　　　　　
  Yamamoto, T.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Japanese Journal of Applied Physics, Volume：47, Number：10 PART 1, First page：7803, Last page：7806, 2008, [Reviewed]
  Thermal oxidation process of silicon carbide (SiC) has been studied by performing in-situ spectroscopic ellipsometry. In our previous work, we, for the first time, found that the growth rates of SiC(000 (1) over bar) C-face at oxidation thicknesses less than around 20 nm are much higher than those given by the Deal-Grove (D-G) model. In this report, we show that such a growth rate enhancement occurs also in the oxidation of SiC(0001) Si-face. By applying the empirical equation proposed by Massoud et al. [J. Electrochem. Soc. 132 (1985) 2685] to the oxidation of SiC Si-face and comparing the temperature and oxygen partial pressure dependences of oxidation rate parameters obtained with those for C-face, we discuss the difference in oxidation mechanism between SiC Si- and C-faces. [DOI: 10.1143/JJAP.47.7803]
  JAPAN SOCIETY APPLIED PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1143/JJAP.47.7803
  DOI ID：10.1143/JJAP.47.7803, ISSN：0021-4922, ORCID：69201929, SCOPUS ID：60349128534, Web of Science ID：WOS:000260443900009
• Fabrication of MOS capacitors by wet oxidation of p-type 4H-SiC preamorphized by nitrogen ion implantation　　　　　　　　　　　　　　　
  Hijikata, Y.; Yoshida, S.; Moscatelli, F.; Poggi, A.; Solmi, S.; Cristiani, S.; Nipoti, R.
  Materials Science Forum, Volume：556-557, First page：651, Last page：+, 2007, [Reviewed]
  4H-SiC p-type MOS capacitors fabricated by wet oxidation of SiC preamorphized by nitrogen ion (NI) implantation have been investigated. The oxidation rate of the SiC layer preamorphized by high-dose N+ was much larger than that of crystalline SiC, allowing us to reduce the fabrication time of SiC MOS devices. We found that the presence of the surface amorphous SiC layer before the oxidation process did not influence the interface state density in MOS capacitors. Moreover, the shift of the flat-band voltage is not correlated to the amount of nitrogen in the oxide. On the contrary the density of interface states near the valence band edge increased according with the high concentration of the implanted N at the oxide-SiC interface, as in the case of dry oxidation reported by Ciobanu et al. The generation of positive charges due to the nitrogen embedded inside the oxide layer was smaller compared with dry oxidation. We discuss the difference between wet and dry oxidation for MOS capacitors fabricated with N+ implantation.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.556-557.651
  DOI ID：10.4028/www.scientific.net/MSF.556-557.651, ISSN：0255-5476, ORCID：69201921, SCOPUS ID：38449112566, Web of Science ID：WOS:000249653900154
• Characterization of MOS capacitors fabricated on n-type 4H-SiC implanted with nitrogen at high dose　　　　　　　　　　　　　　　
  Poggi, A.; Moscatelli, F.; Hijikata, Y.; Solmi, S.; Sanmartin, M.; Tamarri, F.; Nipoti, R.
  Materials Science Forum, Volume：556-557, First page：639, Last page：+, 2007, [Reviewed]
  Aiming to minimize the interface state density, we fabricated MOS capacitors on n-type 4H-SiC by using wet oxidation of nitrogen implanted layers. We investigated a wide range of implantation dose, including a high dose able to amorphise a surface SiC layer with the intent to reduce the oxidation time. The oxide quality and the SiO2-SiC interface properties were characterized by capacitance-voltage measurements of the MOS capacitors. The proposed process, in which nitrogen is ion-implanted on SiC layer before a wet oxidation, is effective to reduce the density of interface states near the conduction band edge if a high concentration of nitrogen is introduced at the SiO2-SiC interface. We found that only the nitrogen implanted at the oxide-SiC interface reduces the interface states and we did not observe the generation of fixed positive charges in the oxide as a consequence of nitrogen implantation. Furthermore, the concentration of the slow traps evaluated from the Slow Trap Profiling technique was low and did not depend on the nitrogen implantation fluence.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.556-557.639
  DOI ID：10.4028/www.scientific.net/MSF.556-557.639, ISSN：0255-5476, ORCID：47642228, SCOPUS ID：38449091394, Web of Science ID：WOS:000249653900151
• Simultaneous determination of the carrier concentration, mobility and thickness of SiC homo-epilayers using terahertz reflectance spectroscopy　　　　　　　　　　　　　　　
  Oishi, S.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：556-557, First page：423, Last page：+, 2007, [Reviewed]
  We have simultaneously determined the carrier concentration, mobility, and thickness of 414-SiC homo-epilayers with carrier concentration of 10(16)-10(18) cm(-3) from reflectance spectroscopy in the wavenumber range of 20-2000 cm(-1). The spectra at 20-100 cm(-1) and at 80-2000 cm(-1) were measured by using the terahertz time domain spectrometer (THz-TDS) and the Fourier-transform infrared (FTIR) spectrometer, respectively. A modified classical dielectric function (MDF) model was employed for the curve fitting. We have compared the values of free carrier concentrations estimated from the reflectance spectroscopy with the net doping concentrations obtained from C-V measurements, and have discussed the validity of the electrical properties estimated from the reflectance spectroscopy.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.556-557.423
  DOI ID：10.4028/www.scientific.net/MSF.556-557.423, ISSN：0255-5476, ORCID：69201920, SCOPUS ID：38449113387, Web of Science ID：WOS:000249653900101
• Micro-Raman study on the improvement of luminescence efficiency of GaAsN alloys　　　　　　　　　　　　　　　
  Tanioka, K.; Endo, Y.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Yoshita, M.; Akiyama, H.; Onabe, K.
  Journal of Crystal Growth, Volume：298, Number：SPEC. ISS, First page：131, Last page：134, 2007, [Reviewed]
  We have used in situ micro-Raman spectroscopy to clarify the mechanism of the luminescence efficiency improvement of GaAsN alloys by laser irradiation. Raman peak intensity of GaAs-like longitudinal optical (LO) mode phonon was observed to increase with the laser irradiation time. With increasing laser power density, the Raman intensity of GaAs-like LO mode phonon was found to increase more rapidly and to be saturated in a shorter time. Changes in the Raman intensity can be expressed by the same equation used for the luminescence efficiency improvement. Time constants of changes in the Raman intensity were almost in agreement with those of the luminescence efficiency improvement. This indicates that the increase in Raman intensity of GaAs-like LO phonon is closely related to the luminescence efficiency improvement. (c) 2006 Published by Elsevier B.V.
  ELSEVIER, English, Scientific journal
  DOI：https://doi.org/10.1016/j.jcrysgro.2006.10.006
  DOI ID：10.1016/j.jcrysgro.2006.10.006, ISSN：0022-0248, eISSN：1873-5002, ORCID：69201931, SCOPUS ID：33846420651, Web of Science ID：WOS:000244622600030
• Micro-photoluminescence study of nitrogen delta-doped GaAs grown by metalorganic vapor phase epitaxy　　　　　　　　　　　　　　　
  Endo, Y.; Tanioka, K.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Yoshita, M.; Akiyama, H.; Ono, W.; Nakajima, F.; Katayama, R.; Onabe, K.
  Journal of Crystal Growth, Volume：298, Number：SPEC. ISS, First page：73, Last page：75, 2007, [Reviewed]
  We have measured micro-photoluminescence (PL) spectra of nitrogen delta (δ)-doped GaAs with various concentrations. In nitrogen δ-doped GaAs with low concentrations, the micro-PL spectra measured at different positions were individually different. In contrast, almost the same spectra were obtained for nitrogen δ-doped GaAs with higher concentrations and uniformly nitrogen-doped GaAs. The micro-PL study shows that there are no more than a few isoelectronic traps within a diameter of ∼1 μm. This indicates a good prospect for applications of isoelectronic traps to single photon emitting devices. © 2006 Elsevier B.V. All rights reserved.
  Scientific journal
  DOI：https://doi.org/10.1016/j.jcrysgro.2006.10.019
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=33846448766&origin=inward
  DOI ID：10.1016/j.jcrysgro.2006.10.019, ISSN：0022-0248, ORCID：69201951, SCOPUS ID：33846448766, Web of Science ID：WOS:000244622600017
• Photoluminescence study of isoelectronic traps in dilute GaAsN alloys　　　　　　　　　　　　　　　
  Yaguchi, H.; Aoki, T.; Morioke, T.; Hijikata, Y.; Yoshida, S.; Yoshita, M.; Akiyama, H.; Aoki, D.; Onabe, K.
  Physica Status Solidi (C) Current Topics in Solid State Physics, Volume：4, Number：7, First page：2760, Last page：2763, 2007, [Reviewed]
  We have studied photoluminescence spectra in detail to clarify the character of the isoelectronic traps in dilute GaAsN alloys. Several sharp lines have been observed at the lower energy side of the GaAs bandgap and are in good agreement with the nitrogen pair-related emission lines previously reported. In addition to the nitrogen pair-related lines, some other emission lines have been also observed. Compared with the energies of these emission lines and the nitrogen pair-related emission lines, it was found that the energy differences agree with the longitudinal optical phonon energy at the Γ point of GaAs, showing that the character of isoelectronic traps due to nitrogen pairs in dilute GaAsN alloys is significantly contributed from the conduction band state at the Γ point. The temperature dependence of the peak energy of luminescence due to nitrogen pairs also indicates that the character of isoelectronic traps in dilute GaAsN alloys is due to the conduction band edge state at the Γ point of GaAs. For a dilute GaAsN alloy with lower nitrogen concentration, we have observed that the intensity of an emission line increased superlinearly with excitation power. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.
  Scientific journal
  DOI：https://doi.org/10.1002/pssc.200674721
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=49749134309&origin=inward
  DOI ID：10.1002/pssc.200674721, ISSN：1862-6351, ORCID：69201959, SCOPUS ID：49749134309, Web of Science ID：WOS:000248047600135
• RF-MBE growth of InN/InGaN quantum well structures on 3C-SiC substrates　　　　　　　　　　　　　　　
  Hirano, S.; Inoue, T.; Shikata, G.; Orihara, M.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Journal of Crystal Growth, Volume：301, Number：SPEC. ISS., First page：513, Last page：516, 2007, [Reviewed]
  Scientific journal
  DOI：https://doi.org/10.1016/j.jcrysgro.2006.11.117
  DOI ID：10.1016/j.jcrysgro.2006.11.117, ORCID：31489857, SCOPUS ID：33947366440, Web of Science ID：WOS:000246015800118
• RF-MBE growth of a-plane InN on r-plane sapphire with a GaN underlayer　　　　　　　　　　　　　　　
  Shikata, G.; Hirano, S.; Inoue, T.; Orihara, M.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Journal of Crystal Growth, Volume：301-302, Number：SPEC. ISS., First page：517, Last page：520, 2007, [Reviewed]
  a-Plane InN films were grown on r-plane sapphire substrates with GaN underlayers by RF-N-2 plasma molecular beam epitaxy (MBE). X-ray diffraction (XRD) measurements and reflection high-energy electron diffraction (RHEED) observation revealed that the InN films were grown with InN (1 1 (2) over bar 0)parallel to GaN (1 1 (2) over bar 0)parallel to sapphire (2 (2) over bar 0 4). We have carried out micro-Raman scattering measurements for a-plane InN film. Raman peaks were observed at 448, 490 and 598 cm(-1), which can be identified as the A(1) transversal optical (TO), E-2 (high) and E-1 longitudinal optical (LO) mode phonon, respectively. We also carried out photoluminescence (PL) measurements for a-plane InN film. Strong PL was observed between 0.62 and 0.65 eV, which is the lowest ever reported for InN. It is suggested from the excitation intensity and temperature dependence of the PL spectra that the red shift of the PL peak is due to the Franz-Keldysh effect. (c) 2006 Elsevier B.V. All rights reserved.
  ELSEVIER, English, Scientific journal
  DOI：https://doi.org/10.1016/j.jcrysgro.2006.11.072
  DOI ID：10.1016/j.jcrysgro.2006.11.072, ISSN：0022-0248, eISSN：1873-5002, ORCID：69201967, SCOPUS ID：33947363391, Web of Science ID：WOS:000246015800119
• MOS capacitors obtained by wet oxidation of n-type 4H-SiC pre-implanted with nitrogen　　　　　　　　　　　　　　　
  Poggi, A.; Moscatelli, F.; Hijikata, Y.; Solmi, S.; Nipoti, R.
  Microelectronic Engineering, Volume：84, Number：12, First page：2804, Last page：2809, 2007, [Reviewed]
  The manufacture process and the electrical characterization of MOS devices fabricated by wet oxidation of N+ implanted n-type 4H-SiC are here presented. Different implantation fluence and energy values were used with the aims to study the effect of the N concentration both at the SiO2/SiC interface and within the SiO2 film. High doses, able to amorphise a surface SiC layer to take advantage of the faster oxidation rate of amorphous with respect to crystalline SiC, were also evaluated. The electrical quality of the SiO2/SiC system was characterized by capacitance-voltage measurements of MOS capacitors. The analyses of the collected data show that only the implanted N which is located at the oxide-SiC interfaces is effective to reduce the interface states density. On the contrary, the interface states density remains high (the same of an un-implanted reference sample) when the implanted N is completely embedded in the region consumed by the oxidation. Furthermore, none generation of fixed positive charges in the oxide was found as a consequence of the different N concentrations enclosed in the oxide films. These results were independent of the amorphisation of the implanted layer by the N+ ions. Our results demonstrate that by using a suitable N ion implantation and an appropriate wet oxidation treatment, it is possible to obtain a reduced thermal budget process able to decrease the interface state density near the conduction band edge. The proposed approach should be interesting for the development of the MOSFET technology on SiC. (C) 2007 Elsevier B.V. All rights reserved.
  ELSEVIER SCIENCE BV, English, Scientific journal
  DOI：https://doi.org/10.1016/j.mee.2007.01.241
  DOI ID：10.1016/j.mee.2007.01.241, ISSN：0167-9317, ORCID：69201998, SCOPUS ID：36148978949, Web of Science ID：WOS:000252145900006
• Growth rate enhancement of (0001̄)-face silicon-carbide oxidation in thin oxide regime　　　　　　　　　　　　　　　
  Yamamoto, T.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Japanese Journal of Applied Physics, Part 2: Letters, Volume：46, Number：29-32, First page：L770, Last page：L772, 2007, [Reviewed]
  The thermal oxidation of silicon carbide (SiC) has been studied by performing in-situ ellipsometry. We have found that the oxidation rates at the oxidation thickness of approximately less than around 20 nm are much larger than those given using the Deal-Grove (D-G) model, suggesting that the oxidation time dependence of the oxide thickness cannot be explained using the D-G model, i.e., a simple linear-parabolic model, in the initial oxidation stage. By using the empirical relation, which has been proposed for Si oxidation, i.e., adding an exponential term to the D-G equation, the origin of the growth rate enhancement in SiC oxidation has been discussed.
  INST PURE APPLIED PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1143/JJAP.46.L770
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=34548458164&origin=inward
  DOI ID：10.1143/JJAP.46.L770, ISSN：0021-4922, eISSN：1347-4065, ORCID：69201961, SCOPUS ID：34548458164, Web of Science ID：WOS:000249166000018
• Characterization of oxide films on 4H-SiC epitaxial (000(1)over-bar) faces by high-energy-resolution photoemission spectroscopy: Comparison between wet and dry oxidation　　　　　　　　　　　　　　　
  Hijikata, Yasuto; Yaguchi, Hiroyuki; Yoshida, Sadafumi; Takata, Yasutaka; Kobayashi, Keisuke; Nohira, Hiroshi; Hattori, Takeo
  Journal of Applied Physics, Volume：100, Number：5, 2006, [Reviewed]
  Scientific journal
  DOI：https://doi.org/10.1063/1.2345471
  DOI ID：10.1063/1.2345471, ORCID：31489859, SCOPUS ID：33748914131, Web of Science ID：WOS:000240602500065
• Off-angle dependence of characteristics of 4H-SiC-oxide interfaces　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Takata, Y.; Kobayashi, K.; Nohira, H.; Hattori, T.
  Materials Science Forum, Volume：527-529, Number：PART 2, First page：1003, Last page：1006, 2006, [Reviewed]
  SiC-Oxide interfaces on 4H-SiC epitaxial substrates of various off-angles have been characterized by C-V measurements, synchrotron radiation excited photoemission spectroscopy and atomic force microscopy. We found that the interface state density (N-it) and the amount of sub-oxides (S-i) for small off-angle substrates were smaller than those for large off-angle ones. It was also found that there is a good correlation between the amount of the interface states and that of sub-oxides. Step-terrace structures were clearly observed in the surface morphology after the removal of oxide layers for small off-angle substrates, which shows that the interfaces were atomically smooth. These results suggest that the small N-it and S-i values for small off-angle substrates relate to the smoothness of the interface and that high performance SiC MOS devices are expected by using small off-angle substrates.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.527-529.1003
  DOI ID：10.4028/www.scientific.net/MSF.527-529.1003, ISSN：0255-5476, ORCID：69201922, SCOPUS ID：37849053034, Web of Science ID：WOS:000244227200235
• RF-MBE growth of cubic InN films on MgO (001) substrates　　　　　　　　　　　　　　　
  Iwahashi, Y.; Yaguchi, H.; Nishimoto, A.; Orihara, M.; Hijikata, Y.; Yoshida, S.; Hildebrandt, S.; Stutzmann, M.
  Physica Status Solidi C - Current Topics in Solid State Physics, Vol 3, No 6, Volume：3, Number：6, First page：1515, Last page：1518, 2006, [Reviewed]
  Scientific journal
  DOI：https://doi.org/10.1002/pssc.200565312
  DOI ID：10.1002/pssc.200565312, ORCID：31489863, SCOPUS ID：33746362598, Web of Science ID：WOS:000239543600033
• Simultaneous determination of carrier concentration, mobility, and thickness of SiC homoepilayers by infrared reflectance spectroscopy　　　　　　　　　　　　　　　
  Oishi, S.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Japanese Journal of Applied Physics, Part 2: Letters, Volume：45, Number：46-50, First page：L1226, Last page：L1229, 2006, [Reviewed]
  We have simultaneously determined the carrier concentration, mobility, and thickness of 4H-SiC homoepilayers with carrier concentrations of 10(17)-10(18) cm(-3) from infrared reflectance measurements with the wave number range of 80-2000 cm(-1). A modified classical dielectric function model was employed for the fitting analyses. We have prepared n-type epilayers on p-type and n-type substrates for comparison with the values of the carrier concentration and mobility estimated from infrared reflectance measurements with those obtained from Hall-effect measurements and C-V measurements. Through these comparisons, we have confirmed the validity of the values estimated from infrared reflectance measurements.
  INST PURE APPLIED PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1143/JJAP.45.L1226
  DOI ID：10.1143/JJAP.45.L1226, ISSN：0021-4922, ORCID：69201972, SCOPUS ID：34547874643, Web of Science ID：WOS:000243208300002
• Photo-induced improvement of radiative efficiency and structural changes in GaAsN alloys　　　　　　　　　　　　　　　
  Yaguchi, H.; Morioke, T.; Aoki, T.; Shimizu, H.; Hijikata, Y.; Yoshida, S.; Yoshita, M.; Akiyama, H.; Usami, N.; Aoki, D.; Onabe, K.
  Physica Status Solidi (C) Current Topics in Solid State Physics, Volume：3, Number：6, First page：1907, Last page：1910, 2006, [Reviewed]
  We have investigated the excitation power density and nitrogen concentration dependence of the changes in the radiative efficiency of GaAsN alloys to examine the mechanism of the photo-induced improvement of radiative efficiency. With increasing excitation power density, the radiative efficiency increased more rapidly. The measure of the improvement Iafter/I before superlinearly increased with increasing nitrogen concentration x up to ∼1%. This suggests that the nonradiative recombination centers eliminated by photoexcitation are not defects formed by a single nitrogen atom but complexes formed by gathering of several nitrogen atoms. Micro Raman study revealed that the GaAs-like LO mode phonon peak intensity increased with photoexcitation time in a similar way to the increase in the radiative efficiency. Considering that this phenomenon is in a time scale of several seconds, the photo-induced structural changes correspond not to long range inter-diffusion but to local changes in atomic configuration which lead to the decrease in the density of nonradiative recombination centers. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.
  Scientific journal
  DOI：https://doi.org/10.1002/pssc.200565372
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=33746359358&origin=inward
  DOI ID：10.1002/pssc.200565372, ISSN：1862-6351, ORCID：69201981, SCOPUS ID：33746359358, Web of Science ID：WOS:000239543600124
• Real time observation of SiC oxidation using an in-situ ellipsometer　　　　　　　　　　　　　　　
  Kakubari, K.; Kuboki, R.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Materials Science Forum, Volume：527-529, Number：PART 2, First page：1031, Last page：1034, 2006, [Reviewed]
  Real time observation of SiC oxidation was performed using an in-situ ellipsometer over the temperature range from 900 degrees C to 1150 degrees C. The relations between oxide thickness and oxidation time were obtained precisely by virtue of the real time measurements. We analyzed the relations between oxide thickness and oxidation time by applying the Deal and Grove model to obtain the linear and parabolic rate constants. Taking advantage of in-situ measurements, we successfully obtained the oxidation rate constants with high accuracy.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.527-529.1031
  DOI ID：10.4028/www.scientific.net/MSF.527-529.1031, ISSN：0255-5476, ORCID：69201923, SCOPUS ID：34548454843, Web of Science ID：WOS:000244227200242
• Growth of high-quality hexagonal InN on 3C-SiC (001) by molecular beam epitaxy　　　　　　　　　　　　　　　
  Yaguchi, H.; Kitamura, Y.; Nishida, K.; Iwahashi, Y.; Hijikata, Y.; Yoshida, S.; Stutzmann, M.
  Physica Status Solidi C - Conferences and Critical Reviews, Vol 2, No 7, Volume：2, Number：7, First page：2267, Last page：2270, 2005, [Reviewed]
  DOI：https://doi.org/10.1002/pssc.200461386
  DOI ID：10.1002/pssc.200461386, ORCID：31489867, Web of Science ID：WOS:000230421400058
• Characterization of oxide films on SiC epitaxial (000-1) faces by angle-resolved photoemission spectroscopy measurements using synchrotron radiation　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Takata, Y.; Kobayashi, K.; Shin, S.; Nohira, H.; Hattori, T.
  Materials Science Forum, Volume：483-485, First page：585, Last page：588, 2005, [Reviewed]
  Thermal oxide films on SiC epitaxial (000-1) C-faces have been characterized by angle-resolved photoemission spectroscopy (AR-PES). The structure of wet oxide/SiC C-face interface was compared with that of dry oxide/SiC C-face, as well as that of dry oxide/SiC Si-face, in order to clarify why a MOS device of SiC C-face achieved good electrical properties. The improvement in electrical properties was confirmed by AR-PES measurements, evidencing differences in binding energy between SiC and the Si4+ components in Si2p and valence band region, and in binding energy between SiC and the CHx components in C1s. The reason for the improvement in electrical property of MOS devices by use of SiC C-face are discussed in terms of depth profiles of oxide films calculated from the AR-PES results.
  Materials Science Forum, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.483-485.585
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=33748898380&origin=inward
  DOI ID：10.4028/www.scientific.net/MSF.483-485.585, ISSN：0255-5476, eISSN：1662-9752, ORCID：69201925, SCOPUS ID：33748898380
• Effect of Ar post-oxidation annealing on oxide-4H-SiC interfaces studied by capacitance to voltage measurements and photoemission spectroscopy　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Ishida, Y.; Yoshikawa, M.
  Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, Volume：23, Number：2, First page：298, Last page：303, 2005, [Reviewed]
  The effect of post-oxidation annealing in Ar atmosphere (Ar POA) on 4H-SiC-oxide interfaces has been studied by capacitance to gate-bias voltage (C-V) measurements and photoemission spectroscopy (PES). It was found from the C-V measurements that the shift of the C-V curve disappears when the Ar POA temperature is higher than 600 °C. On the other hand, angle-resolved x-ray photoelectron spectroscopy measurements revealed that the thickness of the intermediate layers containing Si1+ oxidation states observed at the interfaces decreases abruptly when the Ar POA temperature exceeds 500 °C. In ultraviolet photoelectron spectra, O2p peaks were changed by Ar POA at temperatures higher than 600 °C, which is the temperature where the shift of the C-V curve disappears in C-V measurements. This shows that the change in O2p bonding by Ar POA is the origin of the shift observed in C-V characteristics. A model of structural changes in the interfaces by Ar POA has been proposed based on the results of PES measurements and those of C-V measurements. © 2005 American Vacuum Society.
  Scientific journal
  DOI：https://doi.org/10.1116/1.1865153
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=31344435125&origin=inward
  DOI ID：10.1116/1.1865153, ISSN：0734-2101, CiNii Articles ID：80017842170, ORCID：69201948, SCOPUS ID：31344435125, Web of Science ID：WOS:000227739200013
• Photoemission spectroscopic studies on oxide/SiC interfaces formed by dry and pyrogenic oxidation　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Ishida, Y.; Yoshikawa, M.; Kamiya, T.; Yoshida, S.
  Materials Science Forum, Volume：457-460, Number：II, First page：1341, Last page：1344, 2004, [Reviewed]
  The difference in the structure of oxide/SiC interface between dry and pyrogenic oxidation and the effect of post-oxidation annealing in Ar atmosphere on the interfaces have been studied by X-ray and ultraviolet photoelectron spectroscopy to make clear the interface structures which spoil the electrical properties. It is found that intermediate layers containing Si1+ oxidation states exist in both cases of oxidation method and the thickness of the layer changes by Ar annealing. It is also found that the oxide/SiC band offsets and the structures of O2p peak, observed in valence band spectra, change remarkably by Ar POA in both cases of oxidation method. The bond states at SiC/oxide interfaces have been discussed by considering these results together with the results from C-V measurements.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.457-460.1341
  DOI ID：10.4028/www.scientific.net/MSF.457-460.1341, ISSN：0255-5476, ORCID：69201918, SCOPUS ID：8744311763, Web of Science ID：WOS:000222802200319
• Characterization of electrical properties in high-dose implanted and post-implantation-annealed 4H-SiC wafers using infrared reflectance spectroscopy　　　　　　　　　　　　　　　
  Narita, N.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Senzaki, J.; Nakashima, S.
  Materials Science Forum, Volume：457-460, Number：II, First page：905, Last page：908, 2004, [Reviewed]
  Infrared reflectance spectroscopy has been used to characterize the electrical properties and crystalline damage of high-dose implanted and post-implantation-annealed 4H-SiC. The carrier concentration, mobility and crystalline damage were independently derived from the analysis of the infrared reflectance spectra using the effective medium approximation and the modified dielectric function taking into account the TO and LO phonon damping factors independently. The carrier concentration and mobility in the recrystallized SiC derived from infrared reflectance spectra are in good agreement with those obtained from Hall effect measurements. The annealing temperature dependence of crystalline damage suggests that the impurities are almost activated by the annealing at a temperature as low as 1200degreesC for 30 min, though the crystallinity of the implanted layer is improved with increasing annealing temperature. In addition, it is revealed that the annealing at a temperature as high as 1700degreesC recovers the crystallinity of the implanted layer within I min. These results demonstrate that the infrared reflectance spectroscopy is a useful technique to characterize both the electrical properties and crystalline damage of implanted and post-implantation-annealed layers in SiC wafers simultaneously.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.457-460.905
  DOI ID：10.4028/www.scientific.net/MSF.457-460.905, ISSN：0255-5476, ORCID：69201919, SCOPUS ID：6444226901, Web of Science ID：WOS:000222802200215
• Epitaxial growth of hexagonal and cubic InN films　　　　　　　　　　　　　　　
  Nishida, K.; Kitamura, Y.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.
  Physica Status Solidi (B) Basic Research, Volume：241, Number：12, First page：2839, Last page：2842, 2004, [Reviewed]
  We have grown InN films on 3C-SiC (001) substrates with and without cubic GaN underlayers by RF-N-2 plasma MBE. It was found that, in the case of direct growth on 3C-SiC (001), hexagonal InN grows with the crystal orientation as hexagonal InN (1100)//3C-SiC (110), while, in the case of the growth on cubic GaN underlayers, cubic InN grows with the crystal orientation as cubic InN (110)//cubic GaN (110). Photoluminescence emissions from the cubic and hexagonal InN films were clearly observed at around 0.7 eV.
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/pssb.200405049
  DOI ID：10.1002/pssb.200405049, ISSN：0370-1972, eISSN：1521-3951, ORCID：69201971, SCOPUS ID：7444245442, Web of Science ID：WOS:000224488800047
• Characterization of carrier concentration and mobility in n-type SiC wafers using infrared reflectance spectroscopy　　　　　　　　　　　　　　　
  Narita, K.; Hijikata, Y.; Yaguchi, H.; Yoshida, S.; Nakashima, S.
  Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, Volume：43, Number：8 A, First page：5151, Last page：5156, 2004, [Reviewed]
  We have estimated the free-carrier concentration and drift mobility in n-type 6H-SiC wafers in the carrier concentration range of $10^{17}$–$10^{19}$ cm-3 from far- and mid-infrared (30–2000 cm-1) reflectance spectra obtained at room temperature. A modified classical dielectric function model was employed for the analysis. We found good agreement between the electrical properties derived from infrared reflectance spectroscopy and those derived from Hall effect measurements. We have demonstrated the spatial mapping of carrier concentration and mobility for commercially produced 2 inch SiC wafers.
  INSTITUTE OF PURE AND APPLIED PHYSICS, English, Scientific journal
  DOI：https://doi.org/10.1143/JJAP.43.5151
  DOI ID：10.1143/JJAP.43.5151, ISSN：0021-4922, CiNii Articles ID：150000043643, CiNii Books ID：AA10457675, ORCID：69201989, SCOPUS ID：6444243848, Web of Science ID：WOS:000224841400013
• Receiving Characteristics of a Fabry-Perot Cavity Fiber Optic Ultrasonic Probe　　　　　　　　　　　　　　　
  NAKAMURA Kentaro; HIJIKATA Yasuto
  The transactions of the Institute of Electronics, Information and Communication Engineers. C, Volume：86, Number：12, First page：1340, Last page：1341, Dec. 2003
  copyright(c)2003 IEICE許諾番号：08RB0010光ファイバの先端に微小なファブリペロー共振器を製作し,その共振光波長変調を検出することで音圧を測定する超音波プローブが提案されている.筆者らは, このプローブの指向性と空間分解能を実験的に評価したところ,シングルモードファイバを用いれば2.25MHzに対してほぼ無指向性であること,空間分解能はファブリペロー共振器の大きさ程度であることが明らかになった.
  The Institute of Electronics, Information and Communication Engineers, Japanese
  ISSN：1345-2827, CiNii Articles ID：110003172094, CiNii Books ID：AA11412446
• Electrical Characteristics of Interface Defects in Oxides Grown at 1200℃ in Dry Oxygen Ambient on Silicon Carbide and Their Thermal Annealing Effects　　　　　　　　　　　　　　　
  YOSHIKAWA Masahito; ISHIDA Yuuki; JIKIMOTO Tamotsu; HIJIKATA Yasuto; ITOH Hisayoshi; OKUMURA Hajime; TAKAHASHI Tetsuo; TSUCHIDA Hidekazu; YOSHIDA Sadafumi
  The Transactions of the Institute of Electronics,Information and Communication Engineers. C, Volume：86, Number：4, First page：426, Last page：433, Apr. 2003
  copyright(c)2003 IEICE許諾番号：08RB00101200℃ドライ酸化やそれに引き続いて行われる熱アニーリングが，酸化膜と4積層周期六方晶炭化ケイ素（4H-SiC）基板の界面に与える影響を調べた．n型及びp型4H-SiC基板を1200℃の乾燥酸素雰囲気中で3時間酸化して50 nmの酸化膜を作製した後，酸化膜を500℃から950℃のアルゴン雰囲気中で3時間熱アニーリングした．その酸化膜を用いて金属/酸化膜/半導体（MOS）構造を形成してC-V特性を測定し，酸化膜と4H-SiC界面の電気特性に及ぼす熱アニーリング効果を調べた．1200℃ドライ酸化膜を用いて形成した4H-SiC MOS構造のC-V特性は，電圧軸に沿って正方向へ大きくシフトした．界面には負電荷が蓄積していた．600℃で3時間の熱アニーリングを行うとC-V特性が負方向へシフトし始め，950℃ 3時間の熱アニーリングで電圧シフトが消失した．一方，p型4H-SiC MOS構造のC-V特性を調べると，n型とは反対に電圧軸に沿って負方向へ大きくシフトした．界面には正電荷が蓄積していた．n型とp型のシフト方向の違いと界面欠陥の荷電状態の関連性について調べ，界面欠陥の熱アニーリングのメカニズムを議論した．
  The Institute of Electronics, Information and Communication Engineers, Japanese
  ISSN：1345-2827, CiNii Articles ID：110003172129, CiNii Books ID：AA11412446
• Electrical Characteristics of Interface Defects in Oxides Grown at 1200℃ in Dry Oxygen Ambient on Silicon Carbide and Their　　　　　　　　　　　　　　　
  YOSHIKAWA Masahito; ISHIDA Yuuki; JIKIMOTO Tamotsu; HIJIKATA Yasuto; ITOH Hisayoshi; OKUMURA Hajime; TAKAHASHI Tetsuo; TSUCHIDA Hidekazu; YOSHIDA Sadafumi
  IEICE transactions on electronics, Volume：86, Number：4, First page：688, Last page：688, Apr. 2003
  copyright(c)2003 IEICE許諾番号：08RB0010 http://search.ieice.org/index.html
  The Institute of Electronics, Information and Communication Engineers, English
  ISSN：0916-8524, CiNii Articles ID：110003223445, CiNii Books ID：AA10826283
• Improvement in the luminescence efficiency of GaAsN alloys by photoexcitation　　　　　　　　　　　　　　　
  Yaguchi, H; Morioke, T; Aoki, T; Hijikata, Y; Yoshida, S; Akiyama, H; Usami, N; Aoki, D; Onabe, K; Stutzmann, M
  5th International Conference on Nitride Semiconductors (Icns-5), Proceedings, Volume：0, Number：7, First page：2782, Last page：2784, 2003, [Reviewed]
  We found that photoexcitation with high excitation power density at low temperatures improves the luminescence efficiency of GaAsN alloys. From the temporal change of the PL intensity, the improvement occurs in a few minutes. Micro Raman study shows that structural changes occur in the laser-irradiated region. These indicate that the improvement of luminescence properties is due to photoexcitation-induced local structural changes. Since no distinct PL peak shift was observed after the laser irradiation at low temperatures, photoexcitation is a useful technique to improve the luminescence efficiency only. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  WILEY-VCH, INC, English, Scientific journal
  DOI：https://doi.org/10.1002/pssc.200303514
  DOI ID：10.1002/pssc.200303514, ISSN：1862-6351, ORCID：31489872, Web of Science ID：WOS:000189401700190
• Spectroscopic ellipsometry study on the dielectric functions of GaPN alloys　　　　　　　　　　　　　　　
  Kanaya, H; Yaguchi, H; Hijikata, Y; Yoshida, S; Miyoshi, S; Onabe, K; Stutzmann, M
  5th International Conference on Nitride Semiconductors (Icns-5), Proceedings, Volume：0, Number：7, First page：2753, Last page：2756, 2003, [Reviewed]
  We have determined the complex dielectric functions of GaP 1-xNx alloys using spectroscopic ellipsometry to clarify the electronic structure. With increasing N concentration, the E1-gap peak height for both ε1 and ε2 decreases and the E1-gap energy shifts to higher energies, showing that the electronic state at the L point is considerably changed due to the N incorporation. In the lower energy range, a broad peak appears near the fundamental band gap energy of GaP. With increasing N concentration, this peak becomes broader and the peak height increases. This indicates that the band-edge formation in GaP1-xNx alloys is extremely unique compared to that in conventional semiconductor alloys. © 2003 WILEY-VCH Verlag GmbH & Co. KGaA.
  Scientific journal
  DOI：https://doi.org/10.1002/pssc.200303430
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=33749433192&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=33749433192&origin=inward
  DOI ID：10.1002/pssc.200303430, ISSN：1610-1634, ORCID：31489873, SCOPUS ID：33749433192, Web of Science ID：WOS:000189401700183
• The investigation of 4H-SiC/SiO2 interfaces by optical and electrical measurements　　　　　　　　　　　　　　　
  Ishida, Y.; Takahashi, T.; Okumura, H.; Jikimoto, T.; Tsuchida, H.; Yoshikawa, M.; Tomioka, Y.; Midorikawa, M.; Hijikata, Y.; Yoshida, S.
  Materials Science Forum, Volume：389-393, First page：1013, Last page：1016, 2002, [Reviewed]
  We have investigated SiO2/4H-SiC interfaces by using capacitance-voltage (CV) measurements, spectroscopic ellipsometry (SE) and Fourier-transformed infrared (FTIR). From CV measurements, fairly large amounts of interface traps and negatively trapped charges in oxide layers were observed near the SiO2/4H-SiC interface. By using spectroscopic ellipsometry (SE), we found interface layers between 4H-SiC substrates and SiO2 layers, which have higher refractive indices than those of SiO2and 4H-SiC. The FTIR measurements showed that the Si-O-Si bonds near the SiO2 /4H-SiC interface had a lower stretching frequency compared to that of fused quartz. These results suggest that the interface layers are suboxides.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.389-393.1013
  DOI ID：10.4028/www.scientific.net/MSF.389-393.1013, ISSN：0255-5476, ORCID：47642231, SCOPUS ID：0036433805
• X-ray photoelectron spectroscopy studies of post-oxidation process effects on oxide/SiC interfaces　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshikawa, M.; Yoshida, S.
  Materials Science Forum, Volume：389-393, First page：1033, Last page：1036, 2002, [Reviewed]
  In this report, we carried out x-ray photoclectron spectroscopy measurements on slope shaped oxide films to explore the changes of interfacial structures by post oxidation processes. By the observation of Si2p, C1s and O1s spectra, the bonding states which influence the electrical properties of MOS structures were suggested to be bonds related to carbon. We also discuss the reasons for the improvement of MOS properties by these post oxidation processes.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.389-393.1033
  DOI ID：10.4028/www.scientific.net/MSF.389-393.1033, ISSN：0255-5476, ORCID：47642230, SCOPUS ID：0036429057, Web of Science ID：WOS:000177321100249
• Characterization of the interfaces between SiC and oxide films by spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Tomioka, Y.; Iida, T.; Midorikawa, M.; Tukada, H.; Yoshimoto, K.; Hijikata, Y.; Yaguchi, H.; Yoshikawa, M.; Ishida, Y.; Kosugi, R.; Yoshida, S.
  Materials Science Forum, Volume：389-393, First page：1029, Last page：1032, 2002, [Reviewed]
  Spectroscopic ellipsometry has been used to investigate, for the first time, the optical properties of oxide films on SiC to discuss the difference of the structures of SiC/SiO2 interfaces with oxidation processes, thermal oxidation in dry oxygen, pyrogenic oxidation and low temperature deposition of oxides by chemical vapor deposition. It was found that there exist interface layers with high refractive indices between SiC and SiO2, the values of which are larger than those of SiC and SiO2 and depend on the oxidation process. The validity of the evaluation of refractive indices of the interfaces has also been discussed.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.389-393.1029
  DOI ID：10.4028/www.scientific.net/MSF.389-393.1029, ISSN：0255-5476, ORCID：47642245, SCOPUS ID：0036433806, Web of Science ID：WOS:000177321100248
• Spatial mapping of the carrier concentration and mobility in SiC wafers by micro fourier-transform infrared spectroscopy　　　　　　　　　　　　　　　
  Yaguchi, H.; Narita, K.; Hijikata, Y.; Yoshida, S.; Nakashima, S.; Oyanagi, N.
  Materials Science Forum, Volume：389-393, Number：1, First page：621, Last page：624, 2002, [Reviewed]
  Micro Fourier-trans form infrared (FTIR) spectroscopy has been used to investigate the spatial distribution of the carrier concentration and mobility in SiC wafers. The carrier concentration and mobility were independently derived from the reflectance spectra based on the dielectric function taking into account the effect of phonons and plasmons. The carrier concentration profile obtained for an intentionally inhomogeneous N-doped 6H-SiC wafer coincides well with the spatial distribution of color in the wafer. For commercially available wafers, carrier concentrations are found to increase with approaching the center of the wafers. These results demonstrate that micro FTIR is a nondestructive and noncontact technique to spatially characterize the carrier concentration and mobility in SiC wafers.
  Materials Science Forum, English, Scientific journal
  DOI：https://doi.org/10.4028/www.scientific.net/MSF.389-393.621
  DOI ID：10.4028/www.scientific.net/MSF.389-393.621, ISSN：0255-5476, ORCID：69201924, SCOPUS ID：34247249828, Web of Science ID：WOS:000177321100150
• Measurements of the depth profile of the refractive indices in oxide films on SiC by spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Iida, T; Tomioka, Y; Yoshimoto, K; Midorikawa, M; Tukada, H; Orihara, M; Hijikata, Y; Yaguchi, H; Yoshikawa, M; Itoh, H; Ishida, Y; Yoshida, S
  Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, Volume：41, Number：2A, First page：800, Last page：804, 2002, [Reviewed]
  The depth profiles of the refractive indices in thermally oxidized films on SiC have been measured by spectroscopic ellipsometry. Oxide films etched at an angle were used to obtain the depth profiles of the refractive indices in the oxide films. The apparent refractive indices napp and thicknesses have been evaluated, assuming that the films have optically uniform single layer structures. The experimental results show that the values of napp increase with oxide film thickness, and approach the values for oxide films on Si at around 60 nm in thickness. This feature is almost the same as the changes of refractive indices of oxide films with oxidation time reported previously. These results reveal that the oxide films are not optically uniform and that the optical properties change with depth from the surface. It has been found that the film structure model where the oxide film is composed of two layers, a thin interface layer around 1 nm in thickness with a higher refractive index than those of SiC and SiO2 and a stoichiometric SiO2 layer, the thickness of which changes with film thickness, can explain the thickness dependence of napp observed. These results suggest that there exists an interface layer with high refractive indices at oxide film/SiC interfaces.
  Scientific journal
  DOI：https://doi.org/10.1143/JJAP.41.800
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=0036478462&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=0036478462&origin=inward
  DOI ID：10.1143/JJAP.41.800, ISSN：0021-4922, CiNii Articles ID：110006340837, ORCID：31489875, SCOPUS ID：0036478462, Web of Science ID：WOS:000176451200070
• Spectroscopic ellipsometry study on the electronic structure near the absorption edge of GaAsN alloys　　　　　　　　　　　　　　　
  Yaguchi, H.; Matsumoto, S.; Hijikata, Y.; Yoshida, S.; Maeda, T.; Ogura, M.; Aoki, D.; Onabe, K.
  Physica Status Solidi (B) Basic Research, Volume：228, Number：1, First page：269, Last page：272, 2001, [Reviewed]
  Spectroscopic ellipsometry has been used to investigate the electronic structure near the fundamental absorption edge of GaAsN alloys grown by metalorganic vapor phase epitaxy. The fundamental absorption edge is clearly observed in the imaginary part of the dielectric function and shifts to lower energies with increasing N concentration. In addition, the absorption structure is observed near the E-0 gap energy of GaAs even in GaAsN alloys. This unequivocally shows that the fundamental absorption edge of GaAsN is not shifted from the E-0 gap of GaAs but newly formed by the N incorporation. Thus. the formation of the narrowest band gap of GaAsN alloys is found to be completely different from that of conventional compound semiconductor alloys, such as AlGaAs and GaAsP.
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/1521-3951(200111)228:1<269::AID-PSSB269>3.0.CO;2-3
  DOI ID：10.1002/1521-3951(200111)228:1<269::AID-PSSB269>3.0.CO;2-3, ISSN：0370-1972, ORCID：47642236, SCOPUS ID：0035541085, Web of Science ID：WOS:000172513100060
• Composition analysis of SiO 2 /SiC interfaces by electron spectroscopic measurements using slope-shaped oxide films　　　　　　　　　　　　　　　
  Hijikata, Y.; Yaguchi, H.; Yoshikawa, M.; Yoshida, S.
  Applied Surface Science, Volume：184, Number：1-4, First page：161, Last page：166, 2001, [Reviewed]
  We have characterized SiO2/SiC interfaces by X-ray photoelectron spectroscopy in terms of composition and bonds to clarify the reasons for the problems in silicon carbide metal-oxide-semiconductor field-effect-transistor and MOS structures. The oxide films on 6H-SiC were shaped into slopes by HF chemical etching to obtain the depth profile of the composition and the bondings. An interface layer was found near the SiO2/SiC boundary, where SiO2 stoichiometry is collapsed and there exists the bondings other than Si-O-2 and Si-C. Also, we revealed the differences in the interface properties for different oxidation processes. (C) 2001 Elsevier Science B.V. All rights reserved.
  ELSEVIER, English, Scientific journal
  DOI：https://doi.org/10.1016/S0169-4332(01)00491-3
  DOI ID：10.1016/S0169-4332(01)00491-3, ISSN：0169-4332, eISSN：1873-5584, ORCID：69201992, SCOPUS ID：0035852219, Web of Science ID：WOS:000173000100027
• Photoluminescence study on temperature dependence of band gap energy of GaAsN alloys　　　　　　　　　　　　　　　
  Yaguchi, H.; Kikuchi, S.; Hijikata, Y.; Yoshida, S.; Aoki, D.; Onabe, K.
  Physica Status Solidi (B) Basic Research, Volume：228, Number：1, First page：273, Last page：277, 2001, [Reviewed]
  We have studied the temperature dependence of photo luminescence (PL) spectra of GaAsN alloys. The PL peak energy shift due to the temperature change decreases with increasing N concentration of GaAsN alloys. The localized state emission partly contributes to the decrease in the PL peak energy shift. In addition, the small PL peak energy shift at high temperatures is due to the reduction in the temperature dependence of the band gap energy. From the analysis using the Bose-Einstein statistical expression, the average phonon energy is much larger than that expected from the linear interpolation between GaAs and GaN, indicating that the interaction between electrons and phonons localized at N atoms plays an important role in the reduction of the temperature dependence of the band gap energy of GaAsN alloys.
  WILEY-V C H VERLAG GMBH, English, Scientific journal
  DOI：https://doi.org/10.1002/1521-3951(200111)228:1<273::AID-PSSB273>3.0.CO;2-N
  DOI ID：10.1002/1521-3951(200111)228:1<273::AID-PSSB273>3.0.CO;2-N, ISSN：0370-1972, CiNii Articles ID：80012819598, ORCID：47642250, SCOPUS ID：0035541092, Web of Science ID：WOS:000172513100061
• Wavelength-division-multiplexing in fiber-optic micro-probe array for ultrasonic field measurements　　　　　　　　　　　　　　　
  Hijikata, Y.; Nakamura, K.
  IEICE Transactions on Electronics, Volume：E83-C, Number：3, 2000, [Reviewed]
  Scientific journal
  ORCID：69201927, SCOPUS ID：0033742714
• Characterization of oxide films on SiC by spectroscopic ellipsometry　　　　　　　　　　　　　　　
  Iida, T; Tomioka, Y; Hijikata, Y; Yaguchi, H; Yoshikawa, M; Ishida, Y; Okumura, H; Yoshida, S
  Japanese Journal of Applied Physics Part 2-Letters, Volume：39, Number：10B, First page：L1054-L1056, Last page：L1056, 2000, [Reviewed]
  We have, for the first time, evaluated the optical constants of thermally oxidized films on SiC by spectroscopic ellipsometry, and discussed the characteristics of SiC/SiO2 interfaces. It was found that the effective refractive indices are smaller than those of the oxide films on Si. They increase with oxidation time, or oxide thickness, reaching to the values of Si oxides. The refractive indices also depend on the oxidation methods, and the pyrogenic oxidation brings about larger refractive indices than dry oxidation. The origin of the small refractive indices of oxide films on SiC was discussed in terms of interface structures and composition in comparison with those of oxide films on Si.
  The Japan Society of Applied Physics, English, Scientific journal
  DOI：https://doi.org/10.1143/JJAP.39.L1054
  DOI ID：10.1143/JJAP.39.L1054, ISSN：0021-4922, CiNii Articles ID：110004093448, CiNii Books ID：AA10650595, ORCID：31489882, Web of Science ID：WOS:000090138800014
• Pressure sensitivity of a fiber-optic microprobe for high-frequency ultrasonic field　　　　　　　　　　　　　　　
  Uno, Y; Nakamura, K
  Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers, Volume：38, Number：5B, First page：3120, Last page：3123, 1999, [Reviewed]
  An acoustic microprobe is required to measure high-frequency ultrasonic fields with good spatial resolution. An optical fiber microprobe was proposed in our previous study, which consists of a small optical cavity 100 µm long made at the end of the fiber. The optical path length of the cavity is changed by the applied acoustic field, and the modulation of output light intensity is monitored at the other end of the fiber to derive information of the acoustic field. In the present study, the pressure sensitivity of the fiber-optic microprobe is discussed theoretically and experimentally. Mechanical deformation of the optical cavity by acoustic pressure is calculated by the finite element method (FEM), and the effect of the deformation on the optical property is analyzed for a low finesse microcavity.
  The Japan Society of Applied Physics, English, Scientific journal
  DOI：https://doi.org/10.1143/JJAP.38.3120
  DOI ID：10.1143/JJAP.38.3120, ISSN：0021-4922, CiNii Articles ID：130004526269, ORCID：31489884, Web of Science ID：WOS:000081575800028

• 埼玉大学研究シーズ集2021-23　　　　　　　　　　　　　　　
  Apr. 2021
• 埼玉大学研究マップ　　　　　　　　　　　　　　　
  Oct. 2019
• 埼玉大学研究シーズ集2018-19　　　　　　　　　　　　　　　
  Apr. 2018
  寄稿（P.85）
• 埼玉大学研究シーズ集2016-17　　　　　　　　　　　　　　　
  Apr. 2016
  寄稿（P.74）
• 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), Volume：74th, Number：8, First page：ROMBUNNO.17P-P7-15, Last page：08JL06-4, 31 Aug. 2013
  Creation of short-period InN/GaN superlattices is one of the possible ways of conducting band gap engineering in the green-blue range of the spectrum. The present paper reports results of photoluminescence experiments, including pressure effects, on a superlattice sample consisting of unit cells with one monolayer of InN and 40 monolayers of GaN. The results are compared with calculations performed for different types of superlattices: InN/GaN, InGaN/GaN, and InN/InGaN/GaN with single monolayers of InN and/or InGaN. The superlattices are simulated by band structure calculations based on the local density approximation (LDA) with a semi-empirical correction for the ``LDA gap error''. A similarity is observed between the results of calculations for an InGaN/GaN superlattice (with one monolayer of InGaN) and the experimental results. This indicates that the fabricated InN quantum wells may contain some Ga atoms due to interdiffusion.
  The Japan Society of Applied Physics, Japanese
  DOI：https://doi.org/10.7567/JJAP.52.08JL06
  DOI ID：10.7567/JJAP.52.08JL06, ISSN：0021-4922, J-Global ID：201302285385764625, CiNii Articles ID：40019758965, CiNii Books ID：AA12295836
• 埼玉大学理工学研究科編「理学・工学の散歩道I」　　　　　　　　　　　　　　　
  Nov. 2012
  寄稿（P.112〜113）
• Theoretical studies for Si and C emission into SiC layer during oxidation　　　　　　　　　　　　　　　
  土方 泰斗; 矢口 裕之; 吉田 貞史
  埼玉大学工学部紀要 第一部 論文集, Volume：44, First page：34, Last page：37, 2010
  To understand the structure of SiC-oxide interface more in detail, we propose a theory for calculating the depth profiles of Si and C emitted into SiC layer during oxidation. Simulations of the depth profiles of Si and C interstitials results in the structures analogous with those observed from a spectroscopic ellipsometry. To determine the diffusivities of Si and C interstitials, we performed capacitance-voltage measurements for examining the re-distribution profiles of nitrogen after oxidation. By comparing between observed and calculated profile, we obtained the self-diffusivity of C interstitials and confirmed that the proposed theory was appropriate to estimate depth profiles of Si and C interstitials emitted into SiC layer.
  埼玉大学工学部広報委員会, Japanese
  ISSN：1880-4446, CiNii Articles ID：120005386082
• 首都圏北部４大学研究室紹介・産学官連携の入り口「４u」　　　　　　　　　　　　　　　
  First page：137, Last page：138, 2009
  研究室紹介記事
• Characterization of oxidizing interface and elucidation of oxidation mechanism of SiC semiconductor using spectroscopic ellipsometry　　　　　　　　　　　　　　　
  土方 泰斗; 矢口 裕之; 吉田 貞史
  埼玉大学工学部紀要 第一部 論文集, Volume：43, First page：17, Last page：21, 2009
  We tried to elucidate the oxidizing interface structure of SiC semiconductor and its oxidation mechanism. First of all, we investigated the analysis method for deriving the thickness of interface layer and verified the validity of the method by analyzing the multi-angle measurement data. As a result of analysis for SiC-oxide interfaces using the analysis method, it is found that the photon energy dispersion of optical constants of the interface layer is similar to that for SiC, the real part of dielectric function is larger than that of SiC, and the imaginary part agrees with that of SiC. In addition, we examined the thickness dependence of optical constants of interface layer and found that the standing point in energy dispersion of the imaginary part of dielectric function shifted to the lower energy-side at 40 nm of oxide thickness. In addition to the observation of SiC-oxide interface, real-time measurements of oxide growth-rates of SiC at various oxidation temperatures were conducted using an in-situ spectroscopic ellipsometer. We tried to apply 'Si and C emission model', which is proposed as the SiC oxidation model by us, to the experimental growth-rate data. As a result, the Si and C emission model well reproduced the growth-rate at the entire oxide thickness region at all of the oxidation temperatures measured for both of (0001)Si-face and (000-1)C-face. Based on the knowledge on oxidizing interface layer and oxidation mechanism obtained from spectroscopic ellipsometry studies, we discuss the structure of interface layer and the formation mechanism of interface states.
  埼玉大学工学部, Japanese
  CiNii Articles ID：120005386070
• 技術＆事業インキュベーション・フォーラム （平成19年1月25日掲載）　　　　　　　　　　　　　　　
  25 Jan. 2008
  ・ニュースリリース、・テクニカルノート
• 解説記事「炭化ケイ素半導体でシリコンの限界を超えろ」　　　　　　　　　　　　　　　
  国際技術情報誌「M&E」, First page：38, Last page：39, Apr. 2007
• 日経BP総合ニュースサイト 「nikkei BP net」（平成19年2月14日掲載）　　　　　　　　　　　　　　　
  nikkei BP net, 14 Feb. 2007
  
  日経BP社
• 日経BPニュースサイト 「Tech-On！」（平成19年2月14日掲載）　　　　　　　　　　　　　　　
  Tech-On！, 14 Feb. 2007
  
  日経BP社
• 技術＆事業インキュベーション・フォーラム （平成19年2月14日掲載）　　　　　　　　　　　　　　　
  14 Feb. 2007
  
• 日経産業新聞（平成19年1月30日掲載）　　　　　　　　　　　　　　　
  日経産業新聞, 30 Jan. 2007
  日本経済新聞社
• 日刊工業新聞 （平成19年1月26日掲載）　　　　　　　　　　　　　　　
  日刊工業新聞, 26 Jan. 2007
  日刊工業新聞社
• 等電子トラップを利用した単一光子発生素子の作製　　　　　　　　　　　　　　　
  矢口裕之; 吉田貞史; 土方泰斗
  Volume：平成17-18年度, 2007
• 酸化膜／炭化珪素半導体界面の窒素による界面順位密度低減のメカニズム解明　　　　　　　　　　　　　　　
  土方泰斗
  Volume：第5号(18年度), First page：592, Last page：593, 2007
• 等電子トラップを利用した単一光子発生素子の作製　　　　　　　　　　　　　　　
  矢口裕之; 吉田貞史; 土方泰斗
  科学研究費補助金(基盤研究(c))研究成果報告書, Volume：平成17-18年度, 2007
• 酸化膜／炭化珪素半導体界面の窒素による界面順位密度低減のメカニズム解明　　　　　　　　　　　　　　　
  土方泰斗
  総合研究機構研究プロジェクト研究成果報告書, Volume：第5号(18年度), First page：592, Last page：593, 2007
• RF-MBE growth of InN epitaxial layers and InN/InGaN quantum wells on SiC substrates　　　　　　　　　　　　　　　
  吉田 貞史; 矢口 裕之; 土方 泰斗; 折原 操
  埼玉大学地域共同研究センター紀要, Volume：5, First page：63, Last page：63, 2004
  埼玉大学地域共同研究センター, Japanese
  ISSN：1347-4758, CiNii Articles ID：120001371469
• Epitaxial Growth of hexagonal and cubic InN using RF-MBE　　　　　　　　　　　　　　　
  吉田 貞史; 矢口 裕之; 土方 泰斗; 折原 操
  Report of Cooperative Research Center, Saitama University, Number：4, First page：61, Last page：64, 2003
  We have grown InN films on 3C-SiC (001) substrates with and without cubic GaN underlayers by RF-MBE. It was found that, in the case of direct growth on 3C-SiC (001), hexagonal InN grows with the crystal orientation as hexagonal InN [1-100]//3C-SiC [110], while, in the case of the growth on cubic GaN underlayers, cubic InN grows with the crystal orientation as cubic InN [110]//cubic GaN [110]. Photoluminescence emissions from the cubic and hexagonal InN films were clearly observed at around 0.7 eV.
  埼玉大学地域共同研究センター, Japanese
  DOI ID：10.24561/00016696, ISSN：1347-4758, CiNii Articles ID：120006388491, CiNii Books ID：AA11808968
• Characterization of Oxide Films on SiC by Spectroscopic Ellipsometry　　　　　　　　　　　　　　　
  吉田 貞史; 矢口 裕之; 土方 泰斗; 折原 操
  Report of Cooperative Research Center, Saitama University, Number：3, First page：41, Last page：48, 2002
  We have developed the method of obtaining the refractive indices of SiC/oxide interfaces by use of spectroscopic ellipsometry, and by using this method we have characterized SiC/oxide interfaces obtained by various oxidation methods and/or post oxidation annealing (POA). We have designed and fabricated the system with which in situ spectroscopic ellipsometry measurements can be carried out. We have observed the initial oxidation stage of SiC. We have also observed the changes of the refractive indices of interfaces by annealing in Ar atmosphere (Ar POA). The changes of atomic bond states at the interface by Ar POA were also observed by angle-resolved XPS and UPS, and compared with the results obtained form optical measurements and C-V measurements. We have developed the measurement method of obtaining carrier density and mobility distribution in SiC wafers by use of microscopic FT-IR. We have shown that the values obtained by this method well agree with those obtained from Hall measurements, suggesting that the method is useful to characterize electrical properties of SiC wafers quantitatively, non-destructively and without contact.
  埼玉大学地域共同研究センター, Japanese
  DOI ID：10.24561/00016656, ISSN：1347-4758, CiNii Articles ID：120006388453, CiNii Books ID：AA11808968
• Development of Deep Ultraviolet Spectroscopic Characterization System for Nano Surface Structure of Wide Bandgap Semiconductors　　　　　　　　　　　　　　　
  矢口 裕之; 土方 泰斗
  埼玉大学地域共同研究センター紀要, Volume：3, First page：40, Last page：40, 2002
  埼玉大学地域共同研究センター, Japanese
  ISSN：1347-4758, CiNii Articles ID：120001371525
• 分光偏光解析等によるSiC酸化膜の評価　　　　　　　　　　　　　　　
  吉田 貞史; 矢口 裕之; 土方 泰斗
  Number：2, First page：150, Last page：156, 2001
  Japanese
  ISSN：1347-4758, CiNii Articles ID：40006206458, CiNii Books ID：AA11808968
• 分光偏向解析等によるSiC酸化膜の評価　　　　　　　　　　　　　　　
  吉田 貞史; 矢口 裕之; 土方 泰斗
  Number：1, First page：25, Last page：32, 2000
  Japanese
  ISSN：1347-4758, CiNii Articles ID：40006206430, CiNii Books ID：AA11808968
• Development of A New Crystal Growth Method of Silicon Carbide High-Temperature Semiconductor - Characterization of Crystal Structures andProperties　　　　　　　　　　　　　　　
  吉田 貞史; 矢口 裕之; 土方 泰斗; 折原 操
  埼玉大学地域共同研究センター紀要, Volume：1, First page：74, Last page：74, 2000
  埼玉大学地域共同研究センター, Japanese
  ISSN：1347-4758, CiNii Articles ID：120001389831

• Handbook of Silicon Carbide Materials and Devices (Chapter8)　　　　　　　　　　　　　　　
  Y. Hijikata, Y.-I. Matsushita, and T. Ohshima
  Taylor & Francis, CRC, May 2023
  Total pages：444
  ISBN：9780367188269
• Silicon carbide (SiC): An extremely tough semiconducting material　　　　　　　　　　　　　　　
  Yasuto Hijikata
  Science Impact ltd., UK, Mar. 2020
  Total pages：3
• Investigation of SiC/Oxide Interface Structures by Spectroscopic Ellipsometry" (Chapter 4) in "Advanced Silicon Carbide Devices and Processing　　　　　　　　　　　　　　　
  Sadafumi Yoshida, Yasuto Hijikata and Hiroyuki Yaguchi
  InTech, Sep. 2015
  Total pages：256
  ISBN：9789535121688
• Physics and Technology of Silicon Carbide Devices　　　　　　　　　　　　　　　
  Yasuto Hijikata
  InTech, Jan. 2013
  Total pages：402
  DOI：https://doi.org/10.5772/3428
  DOI ID：10.5772/3428
• Thermal Oxidation Mechanism of Silicon Carbide　　　　　　　　　　　　　　　
  Yasuto Hijikata, Shuhei Yagi, Hiroyuki Yaguchi and Sadafumi Yoshida
  InTech, Jan. 2013
  Total pages：402
  DOI：https://doi.org/10.5772/50748
  DOI ID：10.5772/50748
• Nondestructive and Contactless Characterization Method for Spatial Mapping of the Thickness and Electrical Properties in Homo-Epitaxially Grown SiC Epilayers Using Infrared Reflectance Spectroscopy　　　　　　　　　　　　　　　
  Sadafumi Yoshida, Yasuto Hijikata and Hiroyuki Yaguchi
  InTech, Jan. 2013
  Total pages：402
  DOI：https://doi.org/10.5772/50749
  DOI ID：10.5772/50749
• SiC/GaNパワーデバイスの製造プロセスと放熱・冷却技術　　　　　　　　　　　　　　　
  技術情報協会, Feb. 2010
  Total pages：340
• SiCパワｰデバイス最新技術 =次世代パワｰエレクトロニクス=　　　　　　　　　　　　　　　
  サイエンス&テクノロジｰ, 2010
  Total pages：309
• テラヘルツ反射分光法による炭化珪素半導体の電気的特性の非破壊マッピング測定　　　　　　　　　　　　　　　
  土方, 泰斗
  [土方泰斗], Mar. 2007
  Total pages：1冊
  CiNii Books：http://ci.nii.ac.jp/ncid/BA82582794
  CiNii Books ID：BA82582794
• 軟X線光電子分光による4H-SiC(000-1)面上酸化膜の評価　　　　　　　　　　　　　　　
  土方泰斗、矢口裕之、吉田貞史、高田恭孝、小林啓介、野平博司、服部健雄
  2005年度前期高輝度光科学研究センター成果報告書, 2005
• Characterization of Thermal Oxidation Films Formed on 4H Silicon Carbide by Soft X-ray Photoelectron Spectroscopy　　　　　　　　　　　　　　　
  Hijikata Y., Yaguchi H., Yoshida S., Ikenaga E., Takata Y., Nohira H., and Hattori T.
  SPring-8 User Experiment Report, 2005
• Properties and Applications of Silicon Carbide　　　　　　　　　　　　　　　
  Yasuto Hijikata, Hiroyuki Yaguchi, and Sadafumi Yoshida
  INTECH open access publisher
  Total pages：535
  DOI：https://doi.org/10.5772/14591
  DOI ID：10.5772/14591

• Polarization-Sensitive Quantum Imaging Using an Entangled-Photon Source　　　　　　　　　　　　　　　
  M. Samad; M. Shimizu; Y. Hijikata
  Mar. 2025
  English, Oral presentation
• ITO透明導電膜によるSiC/SiO₂界面単一光子源の発光強度制御　　　　　　　　　　　　　　　
  武藤 隆太; 針井 一哉; 清水 麻希; 木菱 完太; 矢崎 結也; 相川 慎也; 大島 武; 土方 泰斗
  Mar. 2025
  Japanese, Oral presentation
• 4H-SiC中シリコン空孔のODMR特性に対する¹³C核スピンの影響　　　　　　　　　　　　　　　
  山城 宏育; 佐藤 真一郎; 村田 晃一; 花輪 雅史; 山﨑 雄一; 土田 秀一; 土方 泰斗; 大島 武
  Nov. 2024
  Japanese, Poster presentation
• ITO透明導電膜を用いたSiC/SiO₂界面単一光子源の電界制御　　　　　　　　　　　　　　　
  武藤 隆太; 針井 一哉; 清水 麻希; 木菱 完太; 相川 慎也; 大島 武; 土方 泰斗
  Nov. 2024
  Japanese, Poster presentation
• A SiC Single-Photon Emitting Device Embedded with the MOS Interface Color Centers　　　　　　　　　　　　　　　
  Yasuto Hijikata
  The 5th Asia-Pacific Conference on Silicon Carbide and Related Materials (APCSCRM) 2024 (Shenzhen, China), Nov. 2024, [Invited]
  English, Invited oral presentation
• Polarization control of SiO₂/SiC interfacial single-photon sources by oxygen pressure during thermal oxidation　　　　　　　　　　　　　　　
  Rinku Oyama; Yasuto Hijikata
  International Conference on Silicon Carbide and Related Materials (ICSCRM) 2024 (Raleigh, USA), Oct. 2024
  English, Poster presentation
• 高酸素圧熱酸化によるSiO₂/SiC界面単一光子源の偏光制御　　　　　　　　　　　　　　　
  大山 倫句; 土方 泰斗
  Sep. 2024
  Japanese, Oral presentation
• 4H-SiC及びSiO2上Pt/Co強磁性薄膜の磁気異方性制御　　　　　　　　　　　　　　　
  六田 大貴, 針井 一哉, Qixian Liao, 丁 浩, 好田 誠, 土方 泰斗, 大島 武
  第71回応用物理学会春季学術講演会, Mar. 2024, [Domestic conference]
• 低蛍光強度の透明導電膜を用いたNVセンタの電荷制御　　　　　　　　　　　　　　　
  大石 竜嗣, 木菱 完太, 土方 泰斗, 波多野 睦子, 牧野 俊晴, 相川 慎也, 清水 麻希
  第71回応用物理学会春季学術講演会, Mar. 2024, [Domestic conference]
• RFマグネトロンスパッタ法で作製したSnO2:N薄膜のバルク内酸素空孔低減およびバルク内組成の評価　　　　　　　　　　　　　　　
  川口 拓真, 大石 竜嗣, 清水 麻希, 土方 泰斗, 相川 慎也
  第71回応用物理学会春季学術講演会, Mar. 2024, [Domestic conference]
• ナノダイヤモンドNVセンタにおける被膜の影響　　　　　　　　　　　　　　　
  小島 翔太, 山口 智弘, 土方 泰斗, 石橋 幸治, 清水 麻希
  第71回応用物理学会春季学術講演会, Mar. 2024, [Domestic conference]
• 12C濃縮4H-SiC中に形成したシリコン空孔のODMR特性　　　　　　　　　　　　　　　
  山城 宏育, 佐藤 真一郎, 村田 晃一, 花輪 雅史, 張 盛杰, 山﨑 雄一, 土田 秀一, 土方 泰斗, 大島 武
  第71回応用物理学会春季学術講演会, Mar. 2024, [Domestic conference]
• 熱酸化時の酸素圧によるSiO2/SiC界面単一光子源の偏光制御　　　　　　　　　　　　　　　
  大山倫句,土方 泰斗
  先進パワー半導体分科会第10回講演会, Nov. 2023, [Domestic conference]
• Density and polarization controls of the single photon sources formed at the MOS interface　　　　　　　　　　　　　　　
  Y. Hijikata
  APCSCRM2023 (Beijing, China), Nov. 2023, [Invited], [International conference]
  English, Invited oral presentation
• ナノダイヤモンド温度センサを用いたカーボンナノチューブの熱電測定　　　　　　　　　　　　　　　
  杉本 昂暉, 土方 泰斗, 清水 麻希
  第70回応用物理学会春季学術講演会 (四谷/オンライン), Mar. 2023, [Domestic conference]
• 電子線照射により形成した4H-SiC中シリコン空孔の荷電状態とドーピング濃度の関係　　　　　　　　　　　　　　　
  張 盛杰, 佐藤 真一郎, 村田 晃一, 花輪 雅史, 元木 秀, 張 啓航, 土田 秀一, 土方 泰斗, 大島 武
  第70回応用物理学会春季学術講演会 (四谷/オンライン), Mar. 2023, [Domestic conference]
• 電子線照射による 4H-SiC 中窒素・空孔複合欠陥の高濃度形成　　　　　　　　　　　　　　　
  張 啓航, 佐藤 真一郎, 村田 晃一, 花輪 雅史, 元木 秀, 張 盛杰, 土田 秀一, 土方 泰斗, 大島 武
  第70回応用物理学会春季学術講演会 (四谷/オンライン), Mar. 2023, [Domestic conference]
• Characteristics of the single photon sources formed at the MOS interface　　　　　　　　　　　　　　　
  Y. Hijikata
  APCSCRM2022 (Xuzhou, China / Online), Nov. 2022, [Invited], [International conference]
  English, Invited oral presentation
• 高エネルギー電子線照射による4H-SiC中シリコン空孔の高濃度形成　　　　　　　　　　　　　　　
  元木 秀, 佐藤 真一郎, 佐伯 誠一,村田 晃一,増山 雄太, 山﨑 雄一, 土方 泰斗, 大島 武
  第83回応用物理学会秋季学術講演会 (仙台/オンライン), Sep. 2022, [Domestic conference]
• Generation of boron vacancy defects in hexagonal boron nitride by high temperature ion irradiation　　　　　　　　　　　　　　　
  T. Suzuki, Y. Yamazaki, T. Taniguchi, K. Watanabe, Y.-I. Matsushita, Y. Nishiya, Y. Masuyama, Y. Hijikata, T Ohshima
  ICDCM2022 (Lisbon, Portugal), Sep. 2022, [International conference]
• Magnetic Sensitivity of Silicon Vacancies in 4H-SiC at Different Temperatures　　　　　　　　　　　　　　　
  S. Motoki, S.-I. Sato, Y. Masuyama, Y. Yamazaki, S. Saiki, Y. Hijikata, T. Ohshima
  DSQT2022 (Stockholm, Sweden), Jun. 2022, [International conference]
• 4H-SiC 結晶中に形成された窒素空孔センタの偏光特性　　　　　　　　　　　　　　　
  松下 大記, 佐藤 真一郎, 大島 武, 土方 泰斗
  第69回応用物理学会春季学術講演会, Mar. 2022, [Domestic conference]
• 電子線照射によって形成した4H-SiC中シリコン空孔の濃度定量　　　　　　　　　　　　　　　
  元木 秀, 佐藤 真一郎, 増山 雄太, 山﨑 雄一, 土方 泰斗, 大島 武
  第69回応用物理学会春季学術講演会, Mar. 2022, [Domestic conference]
• 高温イオン照射によるhBN中ホウ素空孔欠陥形成　　　　　　　　　　　　　　　
  鈴木 哲太, 山崎 雄一, 谷口 尚, 渡邊 賢司, 松下 雄一郎, 西谷 侑将, 増山 雄太, 土方 泰斗, 大島 武
  第69回応用物理学会春季学術講演会, Mar. 2022, [Domestic conference]
• 低蛍光強度の透明導電膜の形成　　　　　　　　　　　　　　　
  守護 理高, 清水 麻希, 土方 泰斗, 相川 慎也, 森 峻
  第69回応用物理学会春季学術講演会, Mar. 2022, [Domestic conference]
• 熱酸化したSiC半導体表面に形成する単一光子源の偏光特性　　　　　　　　　　　　　　　
  小森翔太,土方 泰斗
  先進パワー半導体分科会第8回講演会, Dec. 2021, [Domestic conference]
• Optically detected magnetic resonance of silicon vacancies in 4H-SiC with different temperatures　　　　　　　　　　　　　　　
  S. Motoki, S.-I. Sato, Y. Masuyama, Y. Yamazaki, S. Saiki, Y. Hijikata, T. Ohshima
  Dec. 2021, [International conference]
• Thermal effects on generation of spin defects in hexagonal boron nitride　　　　　　　　　　　　　　　
  T. suzuki, Y. Yamazaki, T. Taniguchi, K. Watanabe, Y.-I. Matsushita, Y. Masuyama, Y. Hijikata, T Ohshima
  4th International Forum on Quantum Metrology and Sensing (IFQMS) (Online), Dec. 2021, [International conference]
  Japanese, Poster presentation
• ２次元薄膜h-BNのスピン欠陥形成及びその光学特性の測定　　　　　　　　　　　　　　　
  鈴木 哲太,山崎 雄一,谷口 尚,渡邊 賢司,松下 雄一郎,針井 一哉,圓谷 志郎,増山 雄太,土方 泰斗,大島 武
  第82回応用物理学会秋季学術講演会, Sep. 2021, [Domestic conference]
• 4H-SiC中シリコン空孔における 光検出磁気共鳴スペクトルの温度依存性　　　　　　　　　　　　　　　
  元木 秀, 佐藤 真一郎, 増山 雄太, 山﨑 雄一, 土方 泰斗, 大島 武
  Sep. 2021, [Domestic conference]
• Constructing a thermoelectric measurement system by using nitrogen－vacancy center in nanodiamonds　　　　　　　　　　　　　　　
  K. Sugimoto, Y. Hijikata, M. Shimizu
  Jun. 2021, [International conference]
• SiC結晶中窒素空孔センタの量子状態測定　　　　　　　　　　　　　　　
  若林 健,冨高 祐哉,楢原 拓真, 佐藤 真一郎,児島一聡,大島 武, 土方 泰斗
  第68回応用物理学会春季学術講演会, Mar. 2021, [Domestic conference]
• SiC結晶中窒素空孔センタの量子状態測定　　　　　　　　　　　　　　　
  冨高 祐哉,楢原 拓真, 佐藤 真一郎, 大島 武, 児島 一聡, 土方 泰斗
  先進パワー半導体分科会第7回講演会, Dec. 2020, [Domestic conference]
• Structural Identification of the Single-Photon Sources Formed on SiC Surface using Isotope Oxygen　　　　　　　　　　　　　　　
  Y. Hijikata, Y.-i. Matsushita, and T. Ohshima
  4th QST international symposium, Nov. 2020, [International conference]
  English, Poster presentation
• NCVSi- Centers in Silicon Carbide and Their Photoluminescence Properties　　　　　　　　　　　　　　　
  S.-i. Sato, T. Narahara, T. Higuchi, S. Onoda, Y. Yamazaki, Y. Hijikata, B. C. Gibson, A. D. Greentree, T. Ohshima
  The 2nd International Forum on Quantum Metrology and Sensing (IFQMS), Dec. 2019, [International conference]
• 量子ビームを用いて形成した炭化ケイ素中の窒素・空孔複合欠陥の 近赤外発光特性　　　　　　　　　　　　　　　
  佐藤 真一郎, 楢原 拓真, 山崎 雄一, 樋口 泰成, 小野田 忍, 土方 泰斗, Brant C. Gibson, Andrew D. Greentree, 大島 武
  QST高崎サイエンスフェスタ2019, Dec. 2019, [Domestic conference]
• SiCデバイス内に作製したシリコン空孔の光・電気同時励起時における光学特性　　　　　　　　　　　　　　　
  山﨑 雄一,千葉 陽史,佐藤 真一郎,牧野 高絋,山田 尚人,佐藤 隆博,土方 泰斗,児島 一聡,土田 秀一,星野 紀博,大島 武
  先進パワー半導体分科会第6回講演会 (広島), Dec. 2019, [Domestic conference]
• SiC結晶中シリコン空孔の光検出磁気共鳴信号にアニール温度が及ぼす影響　　　　　　　　　　　　　　　
  千葉 陽史,山﨑 雄一,牧野 高絋,佐藤 真一郎,山田 尚人,佐藤 隆博,児島 一聡,土方 泰斗,大島 武
  先進パワー半導体分科会第6回講演会 (広島), Dec. 2019, [Domestic conference]
• 4H-SiC中の窒素・空孔複合欠陥の形成量と窒素不純物濃度の関係　　　　　　　　　　　　　　　
  楢原 拓真,佐藤 真一郎,児島 一聡,山﨑 雄一,土方 泰斗,大島 武
  先進パワー半導体分科会第6回講演会 (広島), Dec. 2019, [Domestic conference]
• PLイメージング法による異なるオフカット角を有する4H-SiC基板中の酸化誘起積層欠陥の観測　　　　　　　　　　　　　　　
  新田 翔司,土方 泰斗
  先進パワー半導体分科会第6回講演会 (広島), Dec. 2019, [Domestic conference]
• Enhancement of ODMR Contrasts of Silicon Vacancy in SiC by Thermal Treatment　　　　　　　　　　　　　　　
  Y. Chiba, Y. Yamazaki, S.-i. Sato, T. Makino, N. Yamada, T. Satoh, Y. Hijikata, T. Ohshima
  International Conference on Silicon Carbide and Related Materials (ICSCRM) 2019 (Kyoto), Oct. 2019, [International conference]
• Effects of Nitrogen Impurity Concentration on Nitrogen-Vacancy Center Formation in 4H-SiC　　　　　　　　　　　　　　　
  T. Narahara, S.-i. Sato, K. Kojima, Y. Yamazaki, Y. Hijikata, T. Ohshima
  International Conference on Silicon Carbide and Related Materials (ICSCRM) 2019 (Kyoto), Oct. 2019, [International conference]
• Optically detected magnetic resonance study of 3D arrayed silicon vacancies in SiC pn diodes　　　　　　　　　　　　　　　
  Y. Yamazaki, Y. Chiba, S.-i. Sato, T. Makino, N. Yamada, T. Satoh, K. Kojima, Y. Hijikata, H. Tsuchida, N. Hoshino, T. Ohshima
  International Conference on Silicon Carbide and Related Materials (ICSCRM) 2019 (Kyoto), Sep. 2019, [International conference]
• Near Infrared Photoluminescence in High-Purity Semi-Insulating 4H-SiC Irradiated with Energetic Charged Particles　　　　　　　　　　　　　　　
  S.-i. Sato, T. Narahara, S. Onoda, Y. Yamazaki, Y. Hijikata, B. C. Gibson, A. D. Greentree, T. Ohshima
  International Conference on Silicon Carbide and Related Materials (ICSCRM) 2019 (Kyoto), Sep. 2019, [International conference]
• 4H-SiC中の窒素・空孔複合欠陥の形成における窒素不純物濃度の影響　　　　　　　　　　　　　　　
  楢原 拓真,佐藤 真一郎,児島 一聡, 山﨑 雄一,土方 泰斗,大島 武
  第80回応用物理学会秋季学術講演会 (札幌), Sep. 2019, [Domestic conference]
• SiC結晶中シリコン空孔のODMR信号に熱処理温度が及ぼす影響　　　　　　　　　　　　　　　
  千葉 陽史,山崎 雄一郎,牧野 高紘,佐藤 真一郎,山田 尚人,佐藤 隆博,土方 泰斗,大島 武
  第80回応用物理学会秋季学術講演会 (札幌), Sep. 2019, [Domestic conference]
• SiCデバイス内の3次元配列シリコン空孔を用いた光検出磁場共鳴測定　　　　　　　　　　　　　　　
  山崎 雄一郎,千葉 陽史,佐藤 真一郎,牧野 高紘,山田 尚人,佐藤 隆博,土方 泰斗,児嶋 一聡,土田 秀一,星乃 紀博,大島 武
  第80回応用物理学会秋季学術講演会 (札幌), Sep. 2019, [Domestic conference]
• Below-Gap励起光を用いたFET構造4H-SiCの欠陥準位の検出　　　　　　　　　　　　　　　
  小野寺 奎, 鎌田 憲彦, 土方 泰斗, 武山 昭憲, 大島 武, 吉江 徹
  第80回応用物理学会秋季学術講演会 (札幌), Sep. 2019, [Domestic conference]
• Optical properties of simultaneous optically and electrically excited silicon vacancies in SiC pn diodes　　　　　　　　　　　　　　　
  Y. Yamazaki, Y. Chiba, S.-i. Sato, T. Makino, N. Yamada, T. Satoh, K. Kojima, Y. Hijikata, H. Tsuchida, N. Hoshino, T. Ohshima
  QST IRI Workshop, Sep. 2019, [International conference]
• Creation of nitrogen-vacancy centers in SiC by ion irradiation　　　　　　　　　　　　　　　
  T. Ohshima, S.-i. Sato, T. Narahara, Y. Yamazaki, Y. Abe, T. Umeda, Y. Hijikata
  30th International Conference on Defects in Smiconductors (ICDS-30) (Seattle, WA, USA), Jul. 2019, [International conference]
• Room temperature electronic-controllable quantum devices using single-photon sources in SiC crystals　　　　　　　　　　　　　　　
  Y. Hijikata, Y.-i. Matsushita, and T. Ohshima
  2nd The Asia-Pacific Conference on Silicon Carbide and Related Materials (APCSCRM) 2019 (Beijing, China), Jul. 2019, [Invited], [International conference]
  English, Invited oral presentation
• Structure identification and characterization of the single-photon sources formed on the surface of silicon carbide crystal　　　　　　　　　　　　　　　
  Y. Hijikata, Y.-i. Matsushita, and T. Ohshima
  2019 Energy Materials and Nanotechnology on Epitaxy (EMN Meeting on Epitaxy 2019) (Amsterdam, Netherland), Jun. 2019, [Invited], [International conference]
  English, Invited oral presentation
• Position-Selective Silicon Vacancy Formation in Silicon Carbide Devices using Proton Beam Writing　　　　　　　　　　　　　　　
  T. Ohshima, Y. Yamazaki, Y. Chiba, Y. Hijikata, K. Kojima, S.-Y. Lee, W. Kada
  Quantum 2019, May 2019, [International conference]
• Room temperature electronic-driven quantum devices using single defects in silicon carbide semiconductors　　　　　　　　　　　　　　　
  Yasuto Hijikata
  2019 International Seminar on Electron Devices Design and Production (SED-2019) (Prague, Czech), Apr. 2019, [Invited], [International conference]
  English, Keynote oral presentation
• 4H-SiC中の窒素・空孔複合欠陥の形成におけるイオンビーム照射の影響　　　　　　　　　　　　　　　
  楢原 拓真,佐藤 真一郎,土方 泰斗,大島 武
  第66回応用物理学会春季学術講演会(大岡山), Mar. 2019, [Domestic conference]
• γ線照射が炭化ケイ素表面発光中心の生成・発光特性に与える影響　　　　　　　　　　　　　　　
  山崎 雄一郎,常見 大貴,佐藤 真一郎,土方 泰斗,大島 武
  第66回応用物理学会春季学術講演会(大岡山), Mar. 2019, [Domestic conference]
• 同位体酸素を用いたSiC表面に形成される単一光子源の構造推定　　　　　　　　　　　　　　　
  土方 泰斗,松下 雄一郎,大島 武
  第66回応用物理学会春季学術講演会(大岡山), Mar. 2019, [Domestic conference]
• Growth Rate Simulations of Oxide Films on Silicon Carbide based on the Si and C Emission Model　　　　　　　　　　　　　　　
  Yasuto Hijikata
  2018 Conference on Intelligent Computing, Communication & Applied Technologies (CICCAT2018) (Zhuhai, China), Dec. 2018, [Invited], [International conference]
  English, Keynote oral presentation
• Creating single photon sources in SiC pn diodes using proton beam writing　　　　　　　　　　　　　　　
  Y. Chiba, Y. Yamazaki, T. Makino, S.-i. Sato, N. Yamada, T. Sato, K. Kojima, S.-Y. Lee, T. Ohshima, Y. Hijikata
  2018 Conference on Intelligent Computing, Communication & Applied Technologies (CICCAT2018) (Zhuhai, China), Dec. 2018, [International conference]
• プロトンビーム描画により形成されたSiC pnダイオード中シリコン空孔のODMR測定　　　　　　　　　　　　　　　
  千葉 陽史,山﨑 雄一,牧野 高絋,佐藤 真一郎,山田 尚人,佐藤 隆博,児島 一聡,土方 泰斗,大島 武
  第5回講演会(京都), Nov. 2018, [Domestic conference]
• SiC表面に形成される単一光子源の酸化膜厚依存性　　　　　　　　　　　　　　　
  常見 大貴,佐藤 真一郎,山﨑 雄一,牧野 高絋,土方 泰斗,大島 武
  第5回講演会(京都), Nov. 2018, [Domestic conference]
• SiC半導体を用いた非接触給電装置の耐放射線性評価　　　　　　　　　　　　　　　
  赤川拓,川原藤樹,金子裕良,武山昭憲,大島武,土方泰斗
  第5回講演会(京都), Nov. 2018, [Domestic conference]
• プロトンビーム描画により形成したシリコン空孔の光学特性劣化要因に関する研究　　　　　　　　　　　　　　　
  山﨑 雄一,千葉 陽史,牧野 高絋,佐藤 真一郎,山田 尚人,佐藤 隆博,加田 渉,土方 泰斗,児島 一聡,S.-Y.Lee,大島 武
  第5回講演会(京都), Nov. 2018, [Domestic conference]
• 4H-SiC中の窒素・空孔複合欠陥の形成と発光特性　　　　　　　　　　　　　　　
  楢原 拓真,佐藤 真一郎,土方 泰斗,大島 武
  第5回講演会(京都), Nov. 2018, [Domestic conference]
• プロトンビーム描画プロセスがSiC pnダイオード中に導入したシリコン空孔の光学特性に与える影響　　　　　　　　　　　　　　　
  山﨑 雄一,千葉 陽史,牧野 高絋,山田 尚人,佐藤 隆博,土方 泰斗,児島 一聡,大島 武
  第79回応用物理学会秋季学術講演会(名古屋), Sep. 2018, [Domestic conference]
• プロトンビーム描画を用いてSiCデバイス中に作製したシリコン空孔のODMR測定　　　　　　　　　　　　　　　
  千葉 陽史,山﨑 雄一,牧野 高絋,佐藤 真一郎,山田 尚人,佐藤 隆博,児島 一聡,土方 泰斗,大島 武
  第79回応用物理学会秋季学術講演会(名古屋), Sep. 2018, [Domestic conference]
• SiC p+nn+ダイオード中の単一光子源の発光特性に関する考察　　　　　　　　　　　　　　　
  常見 大貴,佐藤 真一郎,山﨑 雄一,牧野 高絋,土方 泰斗,大島 武
  第79回応用物理学会秋季学術講演会(名古屋), Sep. 2018, [Domestic conference]
• SiC半導体表面に形成した単一光子源の低温フォトルミネッセンス特性　　　　　　　　　　　　　　　
  音嶋俊介,松下雄一郎,大島武,土方泰斗
  第79回応用物理学会秋季学術講演会(名古屋), Sep. 2018, [Domestic conference]
• Creation of electrically controllable radiation centers in SiC using proton beam writing　　　　　　　　　　　　　　　
  Y. Chiba, Y. Yamazaki, T. Makino, S.-i. Sato, N. Yamada, T. Sato, K. Kojima, S.-Y. Lee, Y. Hijikata, T. Ohshima
  ECSCRM2018 (Birmingham, UK), Sep. 2018, [International conference]
• Gate Structure Dependence of Charge Collection and Single Event Burnout Tolerance for SiC MOSFETs　　　　　　　　　　　　　　　
  T. Makino, S. Takano, S. Harada, Y. Hijikata, and T. Ohshima
  2018 NSREC (Hawaii, USA), Jul. 2018, [International conference]
• A Macroscopic Simulation of the SiC Thermal Oxidation Process based on the Si and C Emission Model　　　　　　　　　　　　　　　
  Yasuto Hijikata
  APCSCRM 2018 (Beijing, China), Jul. 2018, [Invited], [International conference]
  English, Invited oral presentation
• Radiation Efficiency Enhancement of Single Photon Source near Stacking Fault in 4H-SiC Epilayer　　　　　　　　　　　　　　　
  Y. Hijikata, Y. Furukawa, Y.-i. Matsushita, and T. Ohshima
  2018 Spring Meeting (Strasbourg, France), Jun. 2018, [International conference]
• SiC半導体が実現する室温電子駆動量子センサ　　　　　　　　　　　　　　　
  土方 泰斗,牧野 高紘,佐藤 真一郎,山崎雄一,大島 武
  第２回学術集会, May 2018, [Domestic conference]
• プロトンビーム描画を用いたSiC pinダイオード中への発光中心の形成　　　　　　　　　　　　　　　
  千葉陽史,常見 大貴,本多 智也,牧野 高紘,佐藤 信一郎,山田尚人,佐藤隆博,土方 泰斗,大島 武
  第65回応用物理学会春季学術講演会（早稲田）, Mar. 2018, [Domestic conference]
• 4H-SiC酸化によるアモルファス構造が表面単一光子源に与える影響の理論的分析　　　　　　　　　　　　　　　
  古川頼誉,土方泰斗,大島武,松下雄一郎
  第65回応用物理学会春季学術講演会（早稲田）, Mar. 2018, [Domestic conference]
• チャネルサイズがSiC-MOSFETのガンマ線照射効果に及ぼす影響　　　　　　　　　　　　　　　
  武山昭憲,牧野高紘,大久保秀一,田中雄季,神取幹郎,吉江徹,土方泰斗,大島武
  第65回応用物理学会春季学術講演会（早稲田）, Mar. 2018, [Domestic conference]
• 4H-SiCエピ層中の積層欠陥近傍における単一光子源の発光効率向上　　　　　　　　　　　　　　　
  赤堀周平,古川頼誉,松下雄一郎,大島武,土方泰斗
  第65回応用物理学会春季学術講演会（早稲田）, Mar. 2018, [Domestic conference]
• Functionalization of Silicon Carbide by Particle Irradiation toward Quantum Devices　　　　　　　　　　　　　　　
  T. Ohshima, T. Honda, H. Tsunemi, T. Makino, S.-i. Sato, S. Onoda, Y. Hijikata
  2017 MRS Fall meeting (Boston, USA), Dec. 2017, [International conference]
• バイアス印加によるSiCダイオード中の発光中心の発光強度変化　　　　　　　　　　　　　　　
  本多智也,常見大貴,小野田忍,牧野高紘,佐藤真一郎,土方泰斗,大島武
  第４回講演会（名古屋）, Nov. 2017, [Domestic conference]
• SiC 中の積層欠陥が単一光子光源の発光波長に及ぼす影響の理論的分析　　　　　　　　　　　　　　　
  古川頼誉,土方泰斗,大島武,松下雄一郎
  第４回講演会（名古屋）, Nov. 2017, [Domestic conference]
• トレンチゲート型SiC-MOSFETにおける放射線誘起破壊現象の物理過程探索と耐性評価　　　　　　　　　　　　　　　
  高野 修平,牧野 高紘,原田 信介,土方 泰斗,大島 武
  第４回講演会（名古屋）, Nov. 2017, [Domestic conference]
• 負ゲートバイアス印加によるSiC MOSFETのガンマ線照射劣化挙動　　　　　　　　　　　　　　　
  武山 昭憲,松田 拓磨,三友 啓,村田 航一,牧野 高紘,小野田 忍,大久保 秀一,田中 雄季,神取 幹郎,吉江 徹,土方 泰斗,大島 武
  第４回講演会（名古屋）, Nov. 2017, [Domestic conference]
• SiC p+nn+ダイオードに形成される単一光子源の発光特性　　　　　　　　　　　　　　　
  常見 大貴、本多 智也、牧野 高絋、小野田 忍、佐藤 真一郎、土方 泰斗、大島 武
  第４回講演会（名古屋）, Nov. 2017, [Domestic conference]
• Contraolled 3D Placement of Vacancy Spins for Quantum Applications in Silicon Carbide　　　　　　　　　　　　　　　
  H. Kraus, D. Simin, C. Kasper, W. Kada, Y. Hijikata, C. J. Cochrane, T. Ohshima, V. Dyakonov, G. Astakhov
  ICSCRM2017 (Washington D.C.), Sep. 2017, [International conference]
• Enhanced Single Photon Emission near Stacking Fault in 4H-SiC Epilayer　　　　　　　　　　　　　　　
  Y. Hijikata, S. Akahori, and T. Ohshima
  ICSCRM2017 (Washington D.C.), Sep. 2017, [International conference]
• Various single photon sources observed in SiC pin diodes　　　　　　　　　　　　　　　
  H. Tsunemi, T. Honda, T. Makino, S. Onoda, S-I. Sato, Y. Hijikata, and T. Ohshima
  ICSCRM2017 (Washington D.C.), Sep. 2017, [International conference]
• 4H-SiCエピ層における積層欠陥近傍の単一光子源の発光特性　　　　　　　　　　　　　　　
  赤堀 周平、古川 頼誉、松下 雄一郎、大島 武、土方 泰斗
  第78回応用物理学会秋季学術講演会, Sep. 2017, [Domestic conference]
• SiC p+nn+ダイオードに形成される単一光子源の発光スペクトル　　　　　　　　　　　　　　　
  常見 大貴、本多 智也、牧野 高絋、小野田 忍、佐藤 真一郎、土方 泰斗、大島 武
  第78回応用物理学会秋季学術講演会, Sep. 2017, [Domestic conference]
• SiC p+nn+ダイオード中の発光中心のバイアス電圧による発光強度変化　　　　　　　　　　　　　　　
  本多 智也、常見 大貴、児島 一聡、佐藤 真一郎、牧野 高紘、小野田 忍、土方 泰斗、大島 武
  第78回応用物理学会秋季学術講演会, Sep. 2017, [Domestic conference]
• 負ゲートバイアス印加がSiC MOSFETのガンマ線照射劣化に及ぼす影響　　　　　　　　　　　　　　　
  武山 昭憲,牧野 高紘,大久保 秀一,田中 雄季,神取 幹郎,吉江 徹,土方 泰斗,大島 武
  第78回応用物理学会秋季学術講演会, Sep. 2017, [Domestic conference]
• 重イオン照射によるSiC-MOSFET中の誘起収集電荷の発生過程　　　　　　　　　　　　　　　
  高野 修平,牧野 高紘,原田 信介,土方 泰斗,大島 武
  第78回応用物理学会秋季学術講演会, Sep. 2017, [Domestic conference]
• SiC pinダイオード中の発光中心の観察　　　　　　　　　　　　　　　
  常見大貴、本多智也、牧野高紘、小野田忍、佐藤信一郎、土方泰斗、大島武
  第64回応用物理学会春季学術講演会 (横浜), Mar. 2017, [Domestic conference]
• SiC-MOSFETにおける高エネルギー重イオン誘起電荷収集の電圧依存　　　　　　　　　　　　　　　
  牧野高紘,高野修平,原田信介,児島一聡,土方泰斗,大島武
  第64回応用物理学会春季学術講演会 (横浜), Mar. 2017, [Domestic conference]
• 高温環境によるSiC MOSFETs のガンマ線照射劣化の抑制　　　　　　　　　　　　　　　
  武山昭憲,松田拓磨,三友啓,村田航一,牧野高紘,小野田忍,大久保秀一,田中雄季,神取幹郎,吉江徹,土方泰斗,大島武
  第64回応用物理学会春季学術講演会 (横浜), Mar. 2017, [Domestic conference]
• Creation of Single Photon Sources in Wide Bandgap Semiconductors by Ion Irradiation　　　　　　　　　　　　　　　
  T. Ohshima, T. Honda, S. Onoda, T. Makino, Y. Hijikata, A. Lohrmann, J. R. Klein, B. C. Johnson, J. C. McCallum, S. Castelletto, B. C. Gibson, H. Kraus, V. Dyakonov, G. Astakhov
  MRS-J (Yokohama), Dec. 2016, [International conference]
• Heavy Ion Induced Charge Collection in SiC MOSFETs　　　　　　　　　　　　　　　
  T. Makino, S. Takano, S. Harada, K. Kojima, Y. Hijikata, and T. Ohshima
  2016MRS-J (Yokohama), Dec. 2016, [International conference]
• 高温下ガンマ線照射したSiC MOSFETの照射後経時変化について　　　　　　　　　　　　　　　
  松田拓磨,横関貴史,三友啓,村田航一,牧野高紘,武山昭憲,小野田忍,大島武,大久保秀一,田中雄季,神取幹郎,吉江徹,土方泰斗
  第３回講演会（つくば）, Nov. 2016, [Domestic conference]
• 複合環境下でのガンマ線照射によるSiC MOSFETの電気特性変化　　　　　　　　　　　　　　　
  武山昭憲,松田拓磨,三友啓,村田航一,牧野高紘,小野田忍,大久保秀一,田中雄季,神取幹郎,吉江徹,土方泰斗,大島武
  第３回講演会（つくば）, Nov. 2016, [Domestic conference]
• ガンマ線耐性向上に向けたSiC-MOSFETの構造最適化の検討　　　　　　　　　　　　　　　
  三友啓,松田拓磨,村田航一,横関貴史,牧野高紘,武山昭憲,小野田忍,大島武,大久保秀一,田中雄季,神取幹郎,吉江徹,土方泰斗
  第３回講演会（つくば）, Nov. 2016, [Domestic conference]
• ゲートバイアス印加条件がSiC MOSFETのガンマ線照射効果に及ぼす影響　　　　　　　　　　　　　　　
  村田航一,松田拓磨,三友啓,横関貴史,牧野高紘,武山昭憲,小野田忍,大島武,大久保秀一,田中雄季,神取幹郎,吉江徹,土方泰斗
  第３回講演会（つくば）, Nov. 2016, [Domestic conference]
• プロトンビームライティングによるSiC中へのシリコン空孔の形成　　　　　　　　　　　　　　　
  本多智也,Hannes Kraus,加田渉,小野田忍,須田義規,春山盛善,佐藤隆博,江夏昌志,神谷富裕,川端駿介,三浦健太,花泉修,土方泰斗,大島武
  第３回講演会（つくば）, Nov. 2016, [Domestic conference]
• SiC MOSFETにおける高エネルギー重イオン誘起電荷過剰収集　　　　　　　　　　　　　　　
  牧野高紘、高野修平、原田信介、児島一聡、土方泰斗、大島武
  第３回講演会（つくば）, Nov. 2016, [Domestic conference]
• 重イオン照射によるSiC-MOSFET中の誘起電荷のイオンエネルギー・電圧依存性　　　　　　　　　　　　　　　
  高野修平、牧野高紘、原田信介、児島一聡、土方泰斗、大島武
  第３回講演会（つくば）, Nov. 2016, [Domestic conference]
• Creation of single photon emitters in silicon carbide using particle beam irradiation　　　　　　　　　　　　　　　
  T. Ohshima, T. Honda, S. Onoda, T. Makino, Y. Hijikata, A. Lohrmann, J. R. Klein, B. C. Johnson, J. C. McCallum, S. Castelletto, B. C. Gibson, H. Kraus, V. Dyakonov, G. Astakhov
  IBMM2016 (Wellington, New Zealand), Nov. 2016, [International conference]
• 3C-SiC中の表面に形成される単一発光源の発光特性と表面処理　　　　　　　　　　　　　　　
  本多智也、小野田忍、土方泰斗、大島武
  第77回秋季応用物理学会講演会（新潟）, Sep. 2016, [Domestic conference]
• SiC-MOSFETにおけるイオン誘起電荷過剰収集　　　　　　　　　　　　　　　
  牧野高紘、高野修平、原田信介、児島一聡、土方泰斗、大島武
  第77回秋季応用物理学会講演会（新潟）, Sep. 2016, [Domestic conference]
• 重イオン照射によるSiC-MOSFET中の誘起収集電荷の発生過程　　　　　　　　　　　　　　　
  高野修平、牧野高紘、原田信介、児島一聡、土方泰斗、大島武
  第77回秋季応用物理学会講演会（新潟）, Sep. 2016, [Domestic conference]
• Generation of stacking faults in 4H-SiC epilayer during oxidation　　　　　　　　　　　　　　　
  Ryosuke Asafuji and Yasuto Hijikata
  Sep. 2016, [International conference]
• Creation and Functionalization of Defects in SiC by Irradiation and Thermal Treatment　　　　　　　　　　　　　　　
  T. Ohshima, T. Honda, S. Onoda, T. Makino, Y. Hijikata, A. Lohrmann, J. R. Klein, B. C. Johnson, J. C. McCallum, S. Castelletto, B. C. Gibson, H. Kraus, V. Dyakonov, G. Astakhov
  ECSCRM2016 (Halkidiki, Greek), Sep. 2016, [International conference]
• SiC酸化膜界面のパッシベーション技術　　　　　　　　　　　　　　　
  土方泰斗
  第２回個別討論会（名古屋）, Aug. 2016, [Domestic conference]
• Impacts of Gate Bias and its Variation on Gamma-ray Irradiation Resistance of SiC MOSFETs　　　　　　　　　　　　　　　
  Koichi Murata, Satoshi Mitomo, Takuma Matsuda, Takashi Tokoseki, Takahiro Makino, Akinori Takeyama, Shinobu Onoda,Shuichi Okubo, Yuki Tanaka, Mikio Kandori, Toru Yoshie, Takeshi Ohshima , Yasuto Hijikata
  E-MRS2016 Spring Meeting (Lille, France), May 2016, [International conference]
• Optimum Structures for Gamma-ray Radiation Resistant SiC-MOSFETs　　　　　　　　　　　　　　　
  S. Mitomo, T. Matsuda, K. Murata, T. Tokoseki, T. Makino, A. Takeyama, S. Onoda, T. Ohshima, S. Okubo, Y. Tanaka, M. Kandori, T. Yoshie, Y. Hijikata
  E-MRS2016 Spring Meeting (Lille, France), May 2016, [International conference]
• Development of Super Radiation Resistant Metal-Oxide-Semiconductor Transistor Based on Silicon Carbide　　　　　　　　　　　　　　　
  T. Ohshima, T. Yokoseki, K. Murata, T. Matsuda, S. Mitomo, T. Makino, S. Onoda, Y. Hijikata, Y. Tanaka, M. Kandori, S. Okubo, and T. Yoshie
  R2SRT2016 (Iwaki), Apr. 2016, [International conference]
• 高温・高湿度雰囲気中γ線照射によりSiC MOSFETsに生成される電荷の線量依存　　　　　　　　　　　　　　　
  武山昭憲,松田拓磨,横関貴史,三友啓,村田航一,牧野高紘,小野田忍,大久保秀一,田中雄季,神取幹郎,吉江徹,大島武,土方泰斗
  第63回応用物理学会春季学術講演会, Mar. 2016, [Domestic conference]
• ガンマ線照射耐性における SiC-MOSFET の構造最適化　　　　　　　　　　　　　　　
  三友啓,松田拓磨,村田航一,横関貴史,牧野高紘,武山昭憲,小野田忍,大久保秀一,田中雄季,神取幹郎,吉江徹,大島武,土方泰斗
  第63回応用物理学会春季学術講演会, Mar. 2016, [Domestic conference]
• SiC MOSFET のガンマ線照射効果に及ぼすゲートバイアスの影響　　　　　　　　　　　　　　　
  村田 航一,三友 啓,松田 拓磨,横関貴史,牧野 高紘,武山 昭憲,小野田 忍,大久保 秀一,田中 雄季,神取 幹郎,吉江 徹,大島 武,土方 泰斗
  第63回応用物理学会春季学術講演会, Mar. 2016, [Domestic conference]
• プロトンマイクロビーム照射による SiC 中の発光中心の形成　　　　　　　　　　　　　　　
  本多 智也、Kraus Hannes、加田 渉、小野田 忍、春山 盛善、佐藤 隆博、江夏 昌志、神 谷 富裕、川端 駿介、三浦 健太、花泉 修、土方 泰斗、大島 武
  第63回応用物理学会春季学術講演会, Mar. 2016, [Domestic conference]
• プロトンマイクロビーム照射によるSiC中の発光中心の形成　　　　　　　　　　　　　　　
  本多智也; 本多智也; Kraus HANNES; Kraus HANNES; 加田渉; 小野田忍; 春山盛善; 春山盛善; 佐藤隆博; 江夏昌志; 神谷富裕; 川端駿介; 川端駿介; 三浦健太; 花泉修; 土方泰斗; 大島武
  2016
  2016 - 2016
• A Development of Super Radiation-Hardened Power Electronics Using Silicon Carbide Semiconductors -Toward MGy-Class Radiation Resistivity-　　　　　　　　　　　　　　　
  Y. Hijikata, S. Mitomo, T. Matsuda, K. Murata, T. Yokoseki, T. Makino, A. Takeyama, S. Onoda, Y. Tanaka, M. Kandori, T. Yoshie, and T. Ohshima
  11th RASEDA (Kiryu), Nov. 2015, [Domestic conference]
• Effect of Humidity and temperature on the Radiation Response of SiC MOSFETs　　　　　　　　　　　　　　　
  A. Takeyama, T. Matsuda, T. Yokoseki, S. Mitomo, K. Murata, T. Makino, S. Onoda, Y. Tanaka, M. Kandori, T. Yoshie, Y. Hijikata, and T. Ohshima
  11th RASEDA (Kiryu), Nov. 2015, [International conference]
• Effect of Gate Bias on Radiation Response of SiC MOSFETs　　　　　　　　　　　　　　　
  K. Murata, S. Mitomo, T. Matsuda, T. Yokoseki, T. Makino, H. Abe, S. Onoda, T. Ohshima, A. Takeyama, S. Okubo, Y. Tanaka, M. Kandori, T. Yoshie, and Y. Hijikata
  11th RASEDA (Kiryu), Nov. 2015, [International conference]
• Difference by the Oxide Fabrication Process of the Gamma-ray Irradiation Effect on SiC-MOSFETs　　　　　　　　　　　　　　　
  S. Mitomo, T. Matsuda, K. Murata, T. Yokoseki, T. Makino, A. Takeyama, S. Onoda, T. Ohshima, S. Okubo, Y. Tanaka, M. Kandori, T. Yoshie, and Y. Hijikata
  11th RASEDA (Kiryu), Nov. 2015, [International conference]
• Effect of Gamma-ray Irradiation at High Temperature on the Characteristics of SiC MOSFETs　　　　　　　　　　　　　　　
  T. Yokoseki, T. Matsuda, S. Mitomo, K. Murata, T. Makino, H. Abe, A. Takeyama, S. Onoda, Y. Tanaka, M. Kandori, T. Yoshie, Y. Hijikata, T. Ohshima
  11th RASEDA (Kiryu), Nov. 2015, [International conference]
• Characteristics of Silicon Carbide Metal-Oxide-Semiconductor Capacitors Irradiated with Gamma-rays at Elevated Temperature　　　　　　　　　　　　　　　
  T.Matsuda, T.Yokoseki, S. Mitomo, K. Murata, T. Makino, A. Takeyama, S. Onoda, S. Okubo, Y. Tanaka, M. Kandori, T. Yoshie, T. Ohshima, and Y. Hijikata
  11th RASEDA (Kiryu), Nov. 2015, [International conference]
• 4H-SiCエピ層のプロセス起因欠陥に対するガンマ線照射の影響　　　　　　　　　　　　　　　
  宮崎 寿基,牧野 高紘,武山 昭憲,小野田 忍,大島 武,田中 雄季,神取 幹朗,吉江 徹,土方 泰斗
  先進パワー半導体分科会第2回講演会 (大阪), Nov. 2015, [Domestic conference]
• SiC-MOSFETガンマ線照射に及ぼすパッケージ影響　　　　　　　　　　　　　　　
  三友 啓,松田 拓磨,村田 航一,横関 貴史,牧野 高紘,武山 昭憲,小野田 忍,大島 武,大久保 秀一, 田中 雄季,神取 幹朗,吉江 徹,土方 泰斗
  先進パワー半導体分科会第2回講演会 (大阪), Nov. 2015, [Domestic conference]
• ゲート酸化膜生成方法の異なるSiC MOSFETへのゲートバイアス印加ガンマ線照射　　　　　　　　　　　　　　　
  村田 航一,三友 啓,松田 拓磨,横関 貴史,牧野 高紘,武山 昭憲,小野田 忍,大久保 秀一, 田中 雄季,神取 幹朗,吉江 徹,大島 武,土方 泰斗
  先進パワー半導体分科会第2回講演会 (大阪), Nov. 2015, [Domestic conference]
• 高温下でガンマ線照射されたSiC MOSキャパシタの特性変化　　　　　　　　　　　　　　　
  松田 拓磨,横関 貴史,三友 啓,村田 航一,牧野 高紘,武山 昭憲,小野田 忍,大久保 秀一, 田中 雄季,神取 幹朗,吉江 徹,大島 武,土方 泰斗
  先進パワー半導体分科会第2回講演会 (大阪), Nov. 2015, [Domestic conference]
• 高温・加湿雰囲気下でのガンマ線照射によるSiC MOSFETの電気特性変化　　　　　　　　　　　　　　　
  武山 昭憲,松田 拓磨,横関 貴史,三友 啓,村田 航一,牧野 高紘,小野田 忍,大久保 秀一, 田中 雄季,神取 幹朗,吉江 徹,大島 武,土方 泰斗
  先進パワー半導体分科会第2回講演会 (大阪), Nov. 2015, [Domestic conference]
• Change in Characteristics of SiC MOSFETs by Gamma-ray Irradiation at High Temperature　　　　　　　　　　　　　　　
  Takuma Matsuda, Takashi Tokoseki, Satoshi Mitomo, Koichi Murata, Takahiro Makino, Hiroshi Abe, Akinori Takeyama, Shinobu Onoda, Yuki Tanaka, Mikio Kandori, Toru Yoshie, Yasuto Hijikata, Takeshi Ohshima
  ICSCRM2015 (Giargini Naxos, Italy), Oct. 2015, [International conference]
• Gamma-ray irradiation response of the motor-driver circuit with SiC MOSFETs　　　　　　　　　　　　　　　
  Yugo Kobayashi, Takashi Yokoseki, Takuma Matsuda, Satoshi Mitomo, Koichi Murata, Michihiro Hachisuka, Yasuyoshi Kaneko, Takahiro Makino, Akinori Takeyama, Shinobu Onoda, Takeshi Ohshima, Yuki Tanaka, Mikio Kandori, Toru Yoshie, Yasuto Hijikata
  ICSCRM2015 (Giargini Naxos, Italy), Oct. 2015, [International conference]
• 高温下ガンマ線照射したSiC MOSFETの電気的特性評価　　　　　　　　　　　　　　　
  松田拓磨、横関貴史、三友啓、村田航一、牧野高紘、武山昭憲、小野田忍、大久保秀一、田中雄季、神取幹郎、吉江徹、大島武、土方泰斗
  第76回秋季応用物理学会講演会（名古屋）, Sep. 2015, [Domestic conference]
• 構造の異なるSiC-MOSFETへのガンマ線照射効果　　　　　　　　　　　　　　　
  三友啓、松田拓磨、村田航一、横関貴史、牧野高紘、武山昭憲、小野田忍、大島武、大久保秀一、田中雄季、神取幹郎、吉江徹、土方泰斗
  第76回秋季応用物理学会講演会（名古屋）, Sep. 2015, [Domestic conference]
• 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
  第76回秋季応用物理学会講演会（名古屋）, Sep. 2015, [Domestic conference]
• 酸化膜形成プロセスの異なるSiC MOSFETへのゲートバイアス印加を伴うガンマ線照射効果　　　　　　　　　　　　　　　
  村田航一、三友啓、松田拓磨、横関貴史、牧野高紘、武山昭憲、小野田忍、大久保秀一、田中雄季、神取幹郎、吉江徹、大島武、土方泰斗
  第76回秋季応用物理学会講演会（名古屋）, Sep. 2015, [Domestic conference]
• Si及びC原子放出モデルに基づくSiC熱酸化メカニズムの統合理論　　　　　　　　　　　　　　　
  土方泰斗、浅藤亮祐
  第76回秋季応用物理学会講演会（名古屋）, Sep. 2015, [Domestic conference]
• GaAs MBE成長におけるEr原子の表面偏析の温度依存性　　　　　　　　　　　　　　　
  金日国、高宮健吾、八木修平、土方泰斗、矢口裕之
  第76回秋季応用物理学会講演会（名古屋）, Sep. 2015, [Domestic conference]
• Effect of gamma-ray irradiation on the device process-induced defects in 4H-SiC epilayers　　　　　　　　　　　　　　　
  T.Miyazaki, T. Makino, A. Takeyama, S. Onoda, T. Ohshima, Y. Tanaka, M. Kandori, T. Yoshie, Y. Hijikata
  DRIP-XVI 2015 (Suzhou, China), Sep. 2015, [International conference]
• SiC熱酸化における界面からのSi、C放出と界面欠陥　　　　　　　　　　　　　　　
  土方泰斗
  第１回個別討論会 (東京), Aug. 2015, [Domestic conference]
• Radiation Response of Silicon Carbide Metal-Oxide-Semiconductor Transistors in High Dose Region　　　　　　　　　　　　　　　
  T. Ohshima, T. Yokoseki, K. Murata, T. Matsuda, S. Mitomo, H. Abe, T. Makino, S. Onoda, Y. Hijikata, Y. Tanaka, M. Kandori, S. Okubo, and T. Yoshie
  ISPlasma2015 (Nagoya), Mar. 2015, [International conference]
• ゲートバイアス印加を伴うSiC MOSFETへのガンマ線照射効果　　　　　　　　　　　　　　　
  村田 航一,三友 啓,松田 拓磨,横関貴史,牧野 高紘,阿部 浩之,小野田 忍,大久保 秀一,田中 雄季,神取 幹郎,吉江 徹,大島 武,土方 泰斗
  第62回応用物理学会春季学術講演会予稿集, Mar. 2015, [Domestic conference]
• 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
  第62回応用物理学会春季学術講演会予稿集, Mar. 2015, [Domestic conference]
• GaAs:N δドープ超格子を有する太陽電池の二段階吸収　　　　　　　　　　　　　　　
  鈴木智也, 八木修平, 土方泰斗, 岡田至崇, 矢口裕之
  第62回応用物理学会春季学術講演会予稿集, Mar. 2015, [Domestic conference]
• 高温下ガンマ線照射したSiC MOSFETの耐放射線性評価　　　　　　　　　　　　　　　
  松田拓磨,横関貴史,三友啓,村田航一,牧野高紘,阿部浩之,小野田忍,大久保秀一,田中雄季,神取幹郎,吉江徹,大島武,土方泰斗
  第62回応用物理学会春季学術講演会予稿集, Mar. 2015, [Domestic conference]
• SiC-MOSFETへのガンマ線照射効果の酸化膜作製プロセスによる違い　　　　　　　　　　　　　　　
  三友啓,松田拓磨,村田航一,横関貴史,牧野高紘,阿部浩之,小野田忍,大島武,大久保秀一,田中雄季,神取幹郎,吉江徹,土方泰斗
  第62回応用物理学会春季学術講演会予稿集, Mar. 2015, [Domestic conference]
• 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
  第62回応用物理学会春季学術講演会予稿集, Mar. 2015, [Domestic conference]
• Control of Intermediate Band Configuration in GaAs:N δ-doped Superlattice　　　　　　　　　　　　　　　
  K. Osada, T, Suzuki, S. Yagi, S. Naito, Y. Shoji, Y. Okada, Y. Hijikata, and H. Yaguchi
  6th World Conference on Photovoltaic Energy Conversion (Kyoto), Nov. 2014, [International conference]
• Molecular Beam Epitaxy Growth of Intermediate Band Materials Based on GaAs:N δ-Doped Superlattices　　　　　　　　　　　　　　　
  T. Suzuki, K. Osada, S. Yagi, S. Naito, Y. Hijikata, Y. Okada, and H. Yaguchi
  6th World Conference on Photovoltaic Energy Conversion (Kyoto), Nov. 2014, [International conference]
• In-situ分光エリプソメータによるSiC酸化過程の面方位依存性測定 (II)　　　　　　　　　　　　　　　
  後藤 大祐、八木 修平、土方 泰斗、矢口 裕之
  応用物理学会先進パワー半導体分科会第１回講演会, Nov. 2014, [Domestic conference]
• ガンマ線照射したSiC MOSFETの熱アニールによる特性劣化の回復　　　　　　　　　　　　　　　
  横関貴史、阿部浩之、牧野高紘、小野田忍、田中雄季、神取幹郎、吉江徹、土方泰斗、大島武
  応用物理学会先進パワー半導体分科会第１回講演会, Nov. 2014, [Domestic conference]
• 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　　　　　　　　　　　　　　　
  宮野祐太郎、八木修平、土方泰斗、矢口裕之
  応用物理学会先進パワー半導体分科会第１回講演会, Nov. 2014, [Domestic conference]
• Photoluminescence Study of Oxidation-Induced Stacking Faults in 4H-SiC Epilayers　　　　　　　　　　　　　　　
  Y. Miyano, S. Yagi, Y. Hijikata, H. Yaguchi
  10th Europian Concerence on Silicon Carbide and Related Materilas (Grenoble, France), Sep. 2014, [International conference]
• Surface orientation dependence of SiC oxidation process studied by in-situ spectroscopic ellipsometry　　　　　　　　　　　　　　　
  D. Goto, S. Yagi, Y. Hijikata, H. Yaguchi
  10th Europian Concerence on Silicon Carbide and Related Materilas (Grenoble, France), Sep. 2014, [International conference]
• Recovery of the Electrical Characteristics of SiC MOSFETs Irradiated with Gamma-rays by Thermal Treatments　　　　　　　　　　　　　　　
  T. Yokoseki, H. Abe, T. Makino, S. Onoda, Y. Tanaka, M. Kandori, T. Yoshie, Y. Hijikata and T. Ohshima
  10th Europian Concerence on Silicon Carbide and Related Materilas (Grenoble, France), Sep. 2014, [International conference]
• 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, 内藤俊弥, 土方泰斗, 岡田至崇, 矢口裕之
  第75回応用物理学会秋季学術講演会予稿集, Sep. 2014, [Domestic conference]
• 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
  第75回応用物理学会秋季学術講演会予稿集, Sep. 2014, [Domestic conference]
• ガンマ線照射したSiC MOSFETの特性の安定性　　　　　　　　　　　　　　　
  横関貴史、牧野高紘、阿部浩之、小野田忍、大島武、田中雄季、神取幹郎、吉江徹、土方泰斗
  第75回応用物理学会秋季学術講演会予稿集, Sep. 2014, [Domestic conference]
• GaAs:N δ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
  第75回応用物理学会秋季学術講演会予稿集, Sep. 2014, [Domestic conference]
• Gamma-Ray Irradiation Response of Silicon Carbide Semiconductor Devices: Extremely High Radiation Resistance　　　　　　　　　　　　　　　
  S. Sato, S. Onoda, T. Makino, N. Fujuta, T. Ohshima1, T. Yokoseki, K. Tanaka, Y. Hijikata, Y. Tanaka, M. Kandori, T. Yoshie
  7th International Youth Nuclear Congress (Burgos, Spain), Jul. 2014, [International conference]
• Resonant tunneling of electrons through cubic-InN quantum dots embedded in GaN　　　　　　　　　　　　　　　
  S. Yagi, J. Suzuki, M. Orihara, Y. Hijikata, H. Yaguchi
  The 41st International Symposium on Compound Semiconductors (Montpellier, France), May 2014, [International conference]
• Anomalous excitation power dependence of the luminescence from GaAsN/GaAs quantum well　　　　　　　　　　　　　　　
  Y. Yamazaki, S. Yagi, Y. Hijikata, K. Onabe, H. Yaguchi
  The 41st International Symposium on Compound Semiconductors (Montpellier, France), May 2014, [International conference]
• SiC-MOSキャパシタの電気特性のガンマ線照射線量依存性　　　　　　　　　　　　　　　
  田中量也; 横関貴史; 藤田奈津子; 牧野高紘; 小野田忍; 大島武; 田中雄季; 神取幹郎; 吉江徹; 土方泰斗
  2014
  2014 - 2014
• Si及びSiC-MOSFETのI-V特性に対するガンマ線照射の影響　　　　　　　　　　　　　　　
  横関貴史; 田中量也; 藤田奈津子; 牧野高紘; 小野田忍; 大島武; 田中雄季; 神取幹郎; 吉江徹; 土方泰斗
  2014
  2014 - 2014
• ワイドギャップ半導体MIS界面の電気的評価　　　　　　　　　　　　　　　
  土方泰斗
  SiC及び関連半導体研究 第22回講演会予稿集, Dec. 2013, [Domestic conference]
• In-situ分光エリプソメーターによるSiC酸化過程の面方位依存性測定　　　　　　　　　　　　　　　
  後藤大祐, 八木修平, 土方泰斗, 矢口裕之
  SiC及び関連半導体研究 第22回講演会予稿集, Dec. 2013, [Domestic conference]
• 堆積と熱酸化による4H-SiC MOS構造の作製(II)　　　　　　　　　　　　　　　
  大谷 篤志, 八木 修平, 土方 泰斗, 矢口 裕之
  SiC及び関連半導体研究 第22回講演会予稿集, Dec. 2013, [Domestic conference]
• Co-60ガンマ線によるSiC-MOSFETのI-V特性の劣化評価　　　　　　　　　　　　　　　
  横関貴史, 田中量也, 藤田奈津子, 牧野高紘, 小野田忍, 大島武, 田中雄季, 神取幹郎, 吉江徹, 土方泰斗
  SiC及び関連半導体研究 第22回講演会予稿集, Dec. 2013, [Domestic conference]
• ガンマ線照射後のSiC-MOSキャパシタ及びPiN ダイオードの電気的特性の変化　　　　　　　　　　　　　　　
  田中量也, 横関貴史, 藤田奈津子,岩本直也, 牧野高紘, 小野田忍, 大島武, 田中雄季, 神取幹郎, 吉江徹, 土方泰斗
  SiC及び関連半導体研究 第22回講演会予稿集, Dec. 2013, [Domestic conference]
• 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
  Sep. 2013, [Domestic conference]
• 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, 矢口裕之, 上田修
  Sep. 2013, [Domestic conference]
• 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
  Sep. 2013, [Domestic conference]
• 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
  Sep. 2013, [Domestic conference]
• GaAs:N δ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
  Sep. 2013, [Domestic conference]
• 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
  Sep. 2013, [Domestic conference]
• 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), Aug. 2013, The Japan Society of Applied Physics
  Aug. 2013 - Aug. 2013, Japanese
  Creation of short-period InN/GaN superlattices is one of the possible ways of conducting band gap engineering in the green-blue range of the spectrum. The present paper reports results of photoluminescence experiments, including pressure effects, on a superlattice sample consisting of unit cells with one monolayer of InN and 40 monolayers of GaN. The results are compared with calculations performed for different types of superlattices: InN/GaN, InGaN/GaN, and InN/InGaN/GaN with single monolayers of InN and/or InGaN. The superlattices are simulated by band structure calculations based on the local density approximation (LDA) with a semi-empirical correction for the ``LDA gap error''. A similarity is observed between the results of calculations for an InGaN/GaN superlattice (with one monolayer of InGaN) and the experimental results. This indicates that the fabricated InN quantum wells may contain some Ga atoms due to interdiffusion.
• An attempt for clarification of SiC oxidation mechanism : Common/different point to Si oxidation　　　　　　　　　　　　　　　
  HIJIKATA Yasuto; YAGI Shuhei; YAGUCHI Hiroyuki
  Technical report of IEICE. SDM, Jun. 2013, The Institute of Electronics, Information and Communication Engineers
  Jun. 2013 - Jun. 2013, Japanese
  Further understanding of the SiC oxidization mechanism is indispensable for MOSFET using a SiC semiconductor to exceed the conventional Si-based power devices. In this report, we summarize what have been found so far about the oxidization mechanism of SiC, and the research tendency and its subjects in recent years are introduced in terms of common or difference against Si oxidization.
• 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
  Jun. 2013, [Domestic conference]
• 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,矢口 裕之,土方 泰斗,八木 修平
  Mar. 2013, [Domestic conference]
• 中間バンド型太陽電池へ向けたGaAs中窒素δドープ超光子の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
  Mar. 2013, [Domestic conference]
• RF-MBE法による立方晶InNドット積層構造の作製　　　　　　　　　　　　　　　
  鈴木 潤一郞,折原 操,八木 修平,土方 泰斗,矢口 裕之
  Mar. 2013, [Domestic conference]
• 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
  第61回応用物理学会春季学術講演会予稿集, Mar. 2013, [Domestic conference]
• Si及びSiC-MOSFETのI-V特性に対するガンマ線照射の影響　　　　　　　　　　　　　　　
  横関貴史, 田中量也, 藤田奈津子, 牧野高紘, 小野田忍, 大島武, 田中雄季, 神取幹郎, 吉江徹, 土方泰斗
  第61回応用物理学会春季学術講演会予稿集, Mar. 2013, [Domestic conference]
• SiC-MOSキャパシタの電気特性のガンマ線照射線量依存性　　　　　　　　　　　　　　　
  田中量也, 横関貴史, 藤田奈津子,牧野高紘, 小野田忍, 大島武, 田中雄季, 神取幹郎, 吉江徹, 土方泰斗
  第61回応用物理学会春季学術講演会予稿集, Mar. 2013, [Domestic conference]
• 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
  Oct. 2012, [Domestic conference]
• 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
  Sep. 2012, [Domestic conference]
• 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
  Sep. 2012, [Domestic conference]
• MBE法によるGaAs(001)基板上へのErGaAs混晶の成長　　　　　　　　　　　　　　　
  金 日国, 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
  Sep. 2012, [Domestic conference]
• 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
  Sep. 2012, [Domestic conference]
• 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
  Sep. 2012, [Domestic conference]
• 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
  Sep. 2012, [Domestic conference]
• 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
  Sep. 2012, [Domestic conference]
• 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
  Sep. 2012, [Domestic conference]
• Model calculations of SiC oxide growth rates at sub-atmospheric pressures using the Si and C emission model　　　　　　　　　　　　　　　
  Y. Hijikata, S. Yagi, H. Yaguchi, and S. Yoshida
  ECSCRM2012, Saint-Petersburg, Russia, Sep. 2012, [International conference]
• RF-MBE法によるInN量子ドットの結晶構造制御　　　　　　　　　　　　　　　
  徳田英俊,鈴木潤一郎、折原操,八木修平,土方泰斗,矢口裕之
  Apr. 2012, [Domestic conference]
• 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
  第59回応用物理学関係連合講演会予稿集, Mar. 2012
• 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
  第59回応用物理学関係連合講演会予稿集, Mar. 2012
• 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
  第59回応用物理学関係連合講演会予稿集, Mar. 2012
• 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
  第59回応用物理学関係連合講演会予稿集, Mar. 2012
• 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
  第59回応用物理学関係連合講演会予稿集, Mar. 2012
• MOS構造の電気的特性に対する4H-SiCエピ層中積層欠陥の影響　　　　　　　　　　　　　　　
  外谷 彰悟, 土方 泰斗, 矢口 裕之,吉田 貞史
  第20回SiC及び関連ワイドギャップ半導体研究会講演予稿集, Dec. 2011
• 顕微フォトルミネッセンスを用いた4H-SiCエピ膜中積層欠陥に対する酸化の影響に関する研究　　　　　　　　　　　　　　　
  山形 光, 土方 泰斗, 矢口 裕之, 吉田 貞史
  第20回SiC及び関連ワイドギャップ半導体研究会講演予稿集, Dec. 2011
• SiC熱酸化機構の解明への取り組み　　　　　　　　　　　　　　　
  土方 泰斗, 矢口 裕之, 吉田 貞史
  第20回SiC及び関連ワイドギャップ半導体研究会予稿集, Dec. 2011
• Biexciton Emission from Single Isoelectronic Traps in Nitrogen Atomic-Layey-Doped GaAs　　　　　　　　　　　　　　　
  K. Takamiya, T. Fukushima, S. Yagi, Y. Hijikata, T. Mochizuki, M. Yoshita, H. Akiyama, S. Kuboya, K. Onabe, R. Katayama and H. Yaguchi
  3rd International Workshop on Epitaxial Growth and Fundamental Properties of Semiconductor Nanostructures (Traunkirchen, Austria), Sep. 2011
• 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
  第72回応用物理学会学術講演会予稿集, Sep. 2011
• Single Photon Generation from Nitrogen Atomic-Layer Doped Gallium Arsenide　　　　　　　　　　　　　　　
  K. Takamiya, Y. Endo, T. Fukushima, S. Yagi, Y. Hijikata, T. Mochizuki, M. Yoshita, H. Akiyama, S. Kuboya, K. Onabe, R. Katayama, and H. Yaguchi
  7th International Conference on Processing & Manufacturing of Advanced Materials (Quebec, Canada), Aug. 2011
• SiCの2段階酸化における酸化膜成長速度の測定　　　　　　　　　　　　　　　
  篠田 龍, 土方泰斗, 矢口裕之, 八木修平, 吉田貞史
  第72回応用物理学会学術講演会予稿集, Aug. 2011
• RF-MBE法による立方晶GaN上への立方晶InNドットの成長（II）　　　　　　　　　　　　　　　
  鈴木潤一郎, 折原 操, 八木修平, 土方泰斗, 矢口裕之
  第72回応用物理学会学術講演会予稿集, Aug. 2011
• 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
  第72回応用物理学会学術講演会予稿集, Aug. 2011
• 窒素δドープGaAs(110)中の単一等電子トラップからの発光の偏光特性　　　　　　　　　　　　　　　
  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, 片山竜二, 尾鍋研太郎, 矢口裕之
  第72回応用物理学会学術講演会予稿集, Aug. 2011
• RF-MBE Growth of Semipolar InN(10-13) and InGaN(10-13) on GaAs(110)　　　　　　　　　　　　　　　
  M. Orihara, S. Yagi, Y. Hijikata, H. Yaguchi
  9th International Conference on Nitride Semiconductors (Glasgow, UK), Jul. 2011
• Quantum Well Double Barrier Resonant Tunneling Structures for Selective Contacts of Hot Carrier Solar Cells　　　　　　　　　　　　　　　
  S. Yagi, Y. Hijikata, Y. Okada, H. Yaguchi
  37th IEEE Photovoltaic Specialists Conference (Seattle, USA), Jun. 2011
• InN/p-4H-SiC構造の作製と電気･光学特性評価　　　　　　　　　　　　　　　
  鈴木 潤一郎,折原 操,八木 修平,土方 泰斗,矢口 裕之
  第58回応用物理学関係連合講演会予稿集, Mar. 2011
• InN/p-4H-SiC構造の作製と電気･光学特性評価　　　　　　　　　　　　　　　
  矢野 貴大,折原 操, 八木 修平, 土方 泰斗, 矢口 裕之
  第58回応用物理学関係連合講演会予稿集, Mar. 2011
• GaAs(110)基板上に作製した窒素δドｰプGaAsにおける等電子トラップからの発光特性評価　　　　　　　　　　　　　　　
  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,片山竜二,尾鍋研太郎,矢口裕之
  第58回応用物理学関係連合講演会予稿集, Mar. 2011
• SiC熱酸化機構の解明への取り組み:特にSi酸化との類似点及び相違点について　　　　　　　　　　　　　　　
  土方 泰斗,矢口 裕之,吉田 貞史
  第58回応用物理学関係連合講演会予稿集, Mar. 2011
• In-situ分光エリプソメｰタによるSiC酸化過程の酸素分圧依存性測定　　　　　　　　　　　　　　　
  甲田 景子,土方 泰斗, 八木 修平,矢口 裕之,吉田 貞史
  第19回SiC及び関連ワイドギャップ半導体研究会講演予稿集, Oct. 2010
• 酸化中のS i C 層へのS i 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
  第71回応用物理学会学術講演会予稿集, Sep. 2010
• 窒素δドｰプGaAs/AlGaAsヘテロ構造における等電子トラップからの発光特性評価　　　　　　　　　　　　　　　
  高宮 健吾,遠藤 雄太,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,サノーピン サクンタム,矢口 裕之
  第71回応用物理学会学術講演会予稿集, Sep. 2010
• 窒素δドｰプGaAs 中の等電子トラップを形成する窒素原子対配列に関する研究　　　　　　　　　　　　　　　
  星野 真也,遠藤 雄太,福島 俊之,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
  第71回応用物理学会学術講演会予稿集, Sep. 2010
• 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,石川 輝,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
  第71回応用物理学会学術講演会予稿集, Sep. 2010
• 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
  第71回応用物理学会学術講演会予稿集, Sep. 2010
• 極低窒素濃度GaAsNにおける窒素ペアからの発光の窒素濃度依存性　　　　　　　　　　　　　　　
  石川 輝,八木 修平,土方 泰斗, 吉田 貞史,岡野 真人,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
  第71回応用物理学会学術講演会予稿集, Sep. 2010
• Theoretical studies for Si and C emission into SiC layer during oxidation　　　　　　　　　　　　　　　
  Yasuto Hijikata, Hiroyuki Yaguchi, and Sadafumi Yoshida
  ECSCRM2010, Oslo, Norway, Aug. 2010, [International conference]
• Observation of SiC Oxidation in Ultra-Thin Oxide Regime by In-Situ Spectroscopic Ellipsometry　　　　　　　　　　　　　　　
  Toshiyuki Takaku, Yasuto Hijikata, Hiroyuki Yaguchi and Sadafumi Yoshida
  European Conference on SiC and Related Materials, Sep. 2009
• Model Calculation of SiC Oxide Growth Rate based on the Silicon and Carbon Emission Model　　　　　　　　　　　　　　　
  Yasuto Hijikata, Hiroyuki Yaguchi and Sadafumi Yoshida
  European Conference on SiC and Related Materials, Sep. 2009
• Characterization of 4H-SiC-SiO2 Interfaces by a Deep Ultraviolet Spectroscopic Ellipsometer　　　　　　　　　　　　　　　
  Hideyasu Seki, Takahiro Wakabayashi, Yasuto Hijikata, Hiroyuki Yaguchi and Sadafumi Yoshida
  European Conference on SiC and Related Materials, Sep. 2009
• 様々な面方位基板上に作製した窒素δドープGaAs中の等電子トラップからの発光 (II)　　　　　　　　　　　　　　　
  福島俊之,伊藤正俊,土方泰斗,矢口裕之,吉田貞史,岡野真人,吉田正裕,秋山英文,窪谷茂幸,片山竜二,尾鍋研太郎
  第56回応用物理学関係連合講演会, Mar. 2009
• 窒素をδドープしたGaP中の等電子トラップからの発光 (III)　　　　　　　　　　　　　　　
  伊藤正俊,福島俊之,土方泰斗,矢口裕之,吉田貞史,岡野真人,吉田正裕,秋山英文,窪谷茂幸,片山竜二,尾鍋研太郎
  第56回応用物理学関係連合講演会, Mar. 2009
• 厚い酸化膜領域におけるSiCの酸化速度の測定　　　　　　　　　　　　　　　
  若林敬浩、柴崎俊哉,土方泰斗、矢口裕之、吉田貞史
  第56回応用物理学関係連合講演会, Mar. 2009
• 界面Si及びC原子放出現象に基づくSiC酸化モデル　　　　　　　　　　　　　　　
  土方泰斗、矢口裕之、吉田貞史
  第56回応用物理学関係連合講演会, Mar. 2009
• In-situ 分光エリプソメータによるSiC酸化速度の酸素分圧依存性測定 (II)　　　　　　　　　　　　　　　
  甲田景子,高久英之,土方泰斗、矢口裕之、吉田貞史
  第56回応用物理学関係連合講演会, Mar. 2009
• SiC酸化膜界面の分光エリプソメトリによる評価　　　　　　　　　　　　　　　
  吉田貞史,矢口裕之,土方泰斗
  第17回SiC及び関連ワイドギャップ半導体研究会, Dec. 2008
• 分光エリプソメトリによるSiC/酸化膜界面の光学的評価　　　　　　　　　　　　　　　
  若林敬浩、土方泰斗、矢口裕之、吉田貞史
  第17回SiC及び関連ワイドギャップ半導体研究会, Dec. 2008
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -紫外領域への拡張-　　　　　　　　　　　　　　　
  関秀康,若林敬浩,土方泰斗,矢口裕之,吉田貞史
  第17回SiC及び関連ワイドギャップ半導体研究会, Dec. 2008
• in-situ 分光エリプソメータによるSiCの極薄膜厚領域における酸化過程の観察　　　　　　　　　　　　　　　
  高久英之,土方泰斗,矢口裕之,吉田貞史
  第17回SiC及び関連ワイドギャップ半導体研究会, Dec. 2008
• 界面Si及びC原子放出現象に基づくSiC酸化速度のモデル計算　　　　　　　　　　　　　　　
  土方泰斗,矢口裕之,吉田貞史
  第17回SiC及び関連ワイドギャップ半導体研究会, Dec. 2008
• 第一原理計算を用いた立方晶 GaN の電気的特性解析　　　　　　　　　　　　　　　
  中島洋,土方泰斗,矢口裕之,吉田貞史
  第17回SiC及び関連ワイドギャップ半導体研究会, Dec. 2008
• 分光エリプソメータを用いたGaAsN混晶の電子構造に関する研究　　　　　　　　　　　　　　　
  鈴木直也,土方泰斗,矢口裕之,吉田貞史,片山竜二,尾鍋研太郎
  第69回応用物理学会講演会, Sep. 2008
• 窒素をδドープしたGaP中の等電子トラップからの発光 (II)　　　　　　　　　　　　　　　
  伊藤正俊,福島俊之,土方泰斗,矢口裕之,吉田貞史,吉田正裕,秋山英文,窪谷茂幸,片山竜二,尾鍋研太郎
  第69回応用物理学会講演会, Sep. 2008
• RF-MBE法を用いた4H-SiC(0001)基板上へのInNの直接成長　　　　　　　　　　　　　　　
  折原操,富田康浩,瀧澤伸,佐藤貴紀,土方泰斗,矢口裕之,吉田貞史
  第69回応用物理学会講演会, Sep. 2008
• 様々な面方位基板上に作製した窒素δドープGaAs中の等電子トラップからの発光　　　　　　　　　　　　　　　
  福島俊之,伊藤正俊,土方泰斗,矢口裕之,吉田貞史,吉田正裕,秋山英文,窪谷茂幸,片山竜二,尾鍋研太郎
  第69回応用物理学会講演会, Sep. 2008
• 多入射角分光エリプソメトリによるSiC/酸化膜界面の光学的評価 II　　　　　　　　　　　　　　　
  若林敬浩,関秀康,土方泰斗,矢口裕之,吉田貞史
  第69回応用物理学会講演会, Sep. 2008
• 極低濃度窒素をドーピングしたGaAs中の等電子トラップからの発光　　　　　　　　　　　　　　　
  福島俊之,遠藤雄太,伊藤正俊,土方泰斗,矢口裕之,吉田貞史,吉田正裕,秋山英文,窪谷茂幸,片山竜二,尾鍋研太郎
  第55回応用物理学関係連合講演会, Mar. 2008
• ラマン分光を用いたGaInAsN混晶の発光効率の変化に関する研究　　　　　　　　　　　　　　　
  谷岡健太郎,堀口歩,土方泰斗,矢口裕之,吉田貞史,片山竜二,尾鍋研太郎,吉田正裕,秋山英文
  第55回応用物理学関係連合講演会, Mar. 2008
• 多入射角分光エリプソメトリによるSiC/酸化膜界面の光学的評価　　　　　　　　　　　　　　　
  若林敬浩,関秀康,土方泰斗,矢口裕之,吉田貞史
  第55回応用物理学関係連合講演会, Mar. 2008
• In-situ 分光エリプソメータによるSiCの極薄領域における酸化過程の観察　　　　　　　　　　　　　　　
  高久英之,山本健史,土方泰斗,矢口裕之,吉田貞史
  第55回応用物理学関係連合講演会, Mar. 2008
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化膜厚依存性-　　　　　　　　　　　　　　　
  関秀康,若林敬浩,土方泰斗,矢口裕之,吉田貞史
  第55回応用物理学関係連合講演会, Mar. 2008
• RF-MBE法を用いた3C-SiC基板上への立方晶InNの結晶成長およびその物性評価　　　　　　　　　　　　　　　
  富田康浩,井上赳,折原操,土方泰斗,矢口裕之,吉田貞史,平林康男
  第55回応用物理学関係連合講演会, Mar. 2008
• RF-MBE法により成長した立方晶InNのPL測定 （II）　　　　　　　　　　　　　　　
  井上赳,四方剛,塚越裕介,富田康浩,中島洋,折原操,土方泰斗,矢口裕之,吉田貞史
  第55回応用物理学関係連合講演会, Mar. 2008
• RF-MBE法により成長させたA面InN膜のフォトルミネッセンス特性　　　　　　　　　　　　　　　
  四方剛,井上赳,佐藤貴紀,平山秀樹,折原操,土方泰斗,矢口裕之,吉田貞史
  第55回応用物理学関係連合講演会, Mar. 2008
• In-situ 分光エリプソメータによるSiCの極薄膜厚領域における酸化過程の観察　　　　　　　　　　　　　　　
  高久英之,土方泰斗,矢口裕之,吉田貞史
  Nov. 2007
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性- (2)　　　　　　　　　　　　　　　
  橋本英樹,土方泰斗,矢口裕之,吉田貞史
  Nov. 2007
• In-situ 分光エリプソメータによるSiC酸化速度の酸素分圧依存性測　　　　　　　　　　　　　　　
  山本健史,土方泰斗,矢口裕之,吉田貞史
  Nov. 2007
• SiC酸化速度の極薄膜厚領域におけるモデル計算　　　　　　　　　　　　　　　
  土方泰斗,山本健史,矢口裕之,吉田貞史
  Nov. 2007
• SiC-MOSデバイスの現状と初期酸化過程の観察　　　　　　　　　　　　　　　
  土方泰斗
  第37回日本結晶成長学会国内会議, Nov. 2007
• Oxygen-Partial-Pressure Dependence of SiC Oxidation Rate Studied by In-situ Spectroscopic Ellipsometry　　　　　　　　　　　　　　　
  Takeshi Yamamoto, Yasuto Hijikata, Hiroyuki Yaguchi and Sadafumi Yoshida
  Oct. 2007
• Model Calculation of SiC Oxidation Rates in the Thin Oxide Regime　　　　　　　　　　　　　　　
  Yasuto Hijikata, Takeshi Yamamoto, Hiroyuki Yaguchi and Sadafumi Yoshida
  Oct. 2007
• Improvement of the surface morphology of a-plane InN using low-temperature InN buffer layers　　　　　　　　　　　　　　　
  G. Shikata, S. Hirano, T. Inoue, M. Orihara, Y. Hijikata, H. Yaguchi, and S. Yoshida
  Sep. 2007
• Photoluminescence Study of Hexagonal InN/InGaN Quantum Well Structures Grown on 3C-SiC (001) Substrates by Molecular Beam Epitaxy　　　　　　　　　　　　　　　
  S. Hirano, T. Inoue, G. Shikata, M. Orihara, Y. Hijikata, H. Yaguchi, S. Yoshida
  Sep. 2007
• Photoluminescence of cubic InN films on MgO (001) substrates　　　　　　　　　　　　　　　
  T. Inoue, Y.Iwahashi, S. Oishi, M. Orihara, Y. Hijikata, H. Yaguchi, and S. Yoshida
  Sep. 2007
• 窒素をδドープしたGaP中の等電子トラップからの発光　　　　　　　　　　　　　　　
  伊藤正俊,遠藤雄太,土方泰斗,矢口裕之,吉田貞史,吉田正裕,秋山英文,中島史博,片山竜二,尾鍋研太郎
  第68回応用物理学会講演会, Sep. 2007
• 窒素をδドープしたGaAs における単一の等電子トラップからの発光の偏光特性　　　　　　　　　　　　　　　
  遠藤雄太,伊藤正俊,土方泰斗,矢口裕之,吉田貞史,吉田正裕,秋山英文,中島史博,片山竜二,尾鍋研太郎
  第68回応用物理学会講演会, Sep. 2007
• 光照射によるGaInAsN混晶の発光効率向上に関する研究　　　　　　　　　　　　　　　
  谷岡健太郎,遠藤雄太,伊藤正俊,土方泰斗,矢口裕之,吉田貞史,片山竜二,尾鍋研太郎,吉田正裕,秋山英文
  第68回応用物理学会講演会, Sep. 2007
• 分光エリプソメトリによるInGaN混晶の光学的評価　　　　　　　　　　　　　　　
  塚越裕介,折原操,土方泰斗,矢口裕之,吉田貞史,崔成伯,石谷善博,吉川明彦
  第68回応用物理学会講演会, Sep. 2007
• RF-MBE法を用いた4H-SiC基板(0001)面および(000-1)面上へのInGaN成長　　　　　　　　　　　　　　　
  折原操,四方剛,井上赳,塚越裕介,土方泰斗,矢口裕之,吉田貞史
  第68回応用物理学会講演会, Sep. 2007
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-　　　　　　　　　　　　　　　
  橋本英樹,土方泰斗,矢口裕之,吉田貞史
  第68回応用物理学会講演会, Sep. 2007
• SiC酸化速度の極薄膜厚領域におけるモデル計算　　　　　　　　　　　　　　　
  土方泰斗,山本健史,矢口裕之,吉田貞史
  第68回応用物理学会講演会, Sep. 2007
• In-situ 分光エリプソメータによるSiC酸化速度の酸素分圧依存性測定　　　　　　　　　　　　　　　
  山本健史,土方泰斗,矢口裕之,吉田貞史
  第68回応用物理学会講演会, Sep. 2007
• Twin photoluminescence peaks from single isoelectronic traps in nitrogen delta-doped GaAs　　　　　　　　　　　　　　　
  Y. Endo, K. Tanioka, Y. Hijikata, H. Yaguchi, S. Yoshida, M. Yoshita, H. Akiyama, W. Ono, F. Nakajima, R. Katayama, and K. Onabe
  Jul. 2007
• RF-MBE法を用いた4H-SiC基板上へのInN/InGaN量子井戸構造の作製 (III)　　　　　　　　　　　　　　　
  折原操、平野茂、四方剛、井上赳、塚越裕介、土方泰斗、矢口裕之、吉田貞史
  Mar. 2007
• RF-MBE法を用いた3C-SiC基板上へのInN/InGaN量子井戸構造の作製　　　　　　　　　　　　　　　
  平野茂、四方剛、井上赳、塚越裕介、折原操、土方泰斗、矢口裕之、吉田貞史
  Mar. 2007
• RF-MBE法によるGaNバッファ層を用いたサファイアR面基板上へのA面InNの成長　　　　　　　　　　　　　　　
  四方剛,平野茂,ファリズ・アブドゥルラーシッド,平山秀樹,折原操,土方泰斗,矢口裕之,吉田貞史
  Mar. 2007
• 窒素をδドープしたGaAs における単一の等電子トラップからの発光　　　　　　　　　　　　　　　
  遠藤雄太,土方泰斗,矢口裕之,吉田貞史,吉田正裕,秋山英文,中島史博,片山竜二,尾鍋研太郎
  Mar. 2007
• RF-MBE growth of InN/InGaN quantum well structures on 3C-SiC substrates　　　　　　　　　　　　　　　
  S. Hirano, T. Inoue, G. Shikata, M. Orihara, Y. Hijikata, H. Yaguchi, and S. Yoshida
  2007
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -複数の入射角による測定-　　　　　　　　　　　　　　　
  窪木亮一、橋本英樹、土方泰斗、矢口裕之、吉田貞史
  Nov. 2006
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-　　　　　　　　　　　　　　　
  橋本英樹、窪木亮一、土方泰斗、矢口裕之、吉田貞史
  Nov. 2006
• 窒素イオン注入によりアモルファス化された4H-SiCを用いたMOSキャパシタの作製　　　　　　　　　　　　　　　
  土方泰斗,矢口裕之,吉田貞史,F.Moscatelli,A.Poggi,S.Solmi,R.Nipoti
  Nov. 2006
• テラヘルツ分光法によるSiC エピタキシャル成長膜のキャリヤ濃度、移動度、膜厚の同時評価　　　　　　　　　　　　　　　
  大石慎吾、土方泰斗、矢口裕之、吉田貞史
  Nov. 2006
• In-situ 分光エリプソメータによるSiC酸化速度の酸素分圧依存性測定　　　　　　　　　　　　　　　
  山本健史、土方泰斗、矢口裕之、吉田貞史
  Nov. 2006
• Fabrication of MOS Capacitors by Wet Oxidation of p-type 4H-SiC Preamorphized by Nitrogen Ion Implantation　　　　　　　　　　　　　　　
  Yasuto Hijikata, Sadafumi Yoshida, Francesco Moscatelli, Antonella Poggi, Sandro Solmi, Stefano Cristiani and Roberta Nipoti
  Sep. 2006
• Determination of the Carrier Concentration, Mobility and Thickness of SiC Homo-Epilayers Using Terahertz Reflectance Spectroscopy　　　　　　　　　　　　　　　
  Shingo Oishi, Yasuto Hijikata, Hiroyuki Yaguchi, and Sadafumi Yoshida
  Sep. 2006
• Characterization of MOS Capacitors Fabricated on n-type 4H-SiC Implanted with Nitrogen at High Dose　　　　　　　　　　　　　　　
  Antonella Poggi, Francesco Moscatelli, Yasuto Hijikata, Sandro Solmi, Michele Sanmartin, Fabrizio Tamarri and Roberta Nipoti
  Sep. 2006
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -酸化法、面方位依存性-　　　　　　　　　　　　　　　
  橋本英樹、窪木亮一、土方泰斗、矢口裕之、吉田貞史
  Aug. 2006
• 窒素イオン注入によりアモルファス化された4H-SiCを用いたMOSキャパシタの作製　　　　　　　　　　　　　　　
  土方泰斗,矢口裕之,吉田貞史,F.Moscatelli,A.Poggi,S.Solmi,R.Nipoti
  Aug. 2006
• 赤外反射分光法を用いたSiCエピ膜の電気的特性の評価　　　　　　　　　　　　　　　
  大石慎吾、土方泰斗、矢口裕之、吉田貞史
  Aug. 2006
• 分光エリプソメトリによる高In 組成InGaN の光学的評価　　　　　　　　　　　　　　　
  塚越裕介,折原操,土方泰斗,矢口裕之,吉田貞史,崔成伯,石谷善博,吉川明彦
  Aug. 2006
• 窒素をδドープしたGaAs における等電子トラップの顕微フォトルミネッセンス測定　　　　　　　　　　　　　　　
  遠藤雄太、谷岡健太郎、土方泰斗、矢口裕之、吉田貞史、吉田正裕、秋山英文、中島史博、片山竜二、尾鍋研太郎
  Aug. 2006
• RF-MBE法により成長した立方晶InNのPL測定　　　　　　　　　　　　　　　
  井上赳,平野茂,折原操,土方泰斗,矢口裕之,吉田貞史
  Aug. 2006
• ラマン分光を用いたGaAsN混晶の発光効率向上に関する研究　　　　　　　　　　　　　　　
  谷岡健太郎,遠藤雄太,土方泰斗,矢口裕之,吉田貞史,青木大一郎,尾鍋研太郎
  第53回応用物理学関係連合講演会, 2006
• RF-MBE法を用いた立方晶InNの結晶成長 (IV)　　　　　　　　　　　　　　　
  岩橋洋平,折原操,土方泰斗,矢口裕之,吉田貞史
  第53回応用物理学関係連合講演会, 2006
• RF-MBE法を用いた3C-SiC(001)基板上への六方晶InNの結晶成長　　　　　　　　　　　　　　　
  井上赴,岩橋洋平,平野茂,折原操,土方泰斗,矢口裕之,吉田貞史
  第53回応用物理学関係連合講演会, 2006
• RF-MBE growth of a-plane InN on r-plane sapphire with a GaN underlayer　　　　　　　　　　　　　　　
  G. Shikata, S. Hirano, T. Inoue, M. Orihara, Y. Hijikata, H. Yaguchi and S. Yoshida
  2006
• Real-time Observation of SiC Oxidation using an in situ Ellipsometer　　　　　　　　　　　　　　　
  Yoshida S., Kabubari K., Hijikata Y., Yaguchi H. and Yoshikawa M.
  Optoelectronic Materials and Devices (Berlin), 2006
• Photoluminescence Study of Isoelectronic Traps in Dilute GaAsN alloys　　　　　　　　　　　　　　　
  H. Yaguchi, T. Aoki, T. Morioke, Y. Hijikata, S. Yoshida, M. Yoshita, H. Akiyama, D. Aoki, and K. Onabe
  2006
• Micro-photoluminescence study of nitrogen -doped GaAs grown by metalorganic vapor phase epitaxy　　　　　　　　　　　　　　　
  Y. Endo, K. Tanioka, Y. Hijikata, H. Yaguchi, S. Yoshida, M. Yoshita, H. Akiyama, F. Nakajima, R. Katayama, and K. Onabe
  2006
• Micro-photoluminescence study of nitrogen atomic-layer doped GaAs　　　　　　　　　　　　　　　
  Y. Endo, K. Tanioka, Y. Hijikata, H. Yaguchi, S. Yoshida, M. Yoshita, H. Akiyama, W. Ono, F. Nakajima, R. Katayama, and K. Onabe
  2006
• Micro Raman study on the improvement of luminescence efficiency of GaAsN alloys　　　　　　　　　　　　　　　
  K. Tanioka, Y. Endo, Y. Hijikata, H. Yaguchi, S. Yoshida, M. Yoshita, H. Akiyama, and K. Onabe
  2006
• In-situ 分光エリプソメータによるSiCの酸化の実時間観察　　　　　　　　　　　　　　　
  覚張光一,窪木亮一,山本健史,土方泰斗,矢口裕之,吉田貞史
  第53回応用物理学関係連合講演会, 2006
• RF-MBE法を用いた中間組成InGaN膜上へのInN/InGaN量子井戸構造の作製　　　　　　　　　　　　　　　
  平野茂,岩橋洋平,折原操,土方泰斗,矢口裕之,吉田貞史
  第66回応用物理学会学術講演会, Sep. 2005
• RF-MBE法を用いた4H-SiC基板上へのInN/InGaN量子井戸構造の作製 （II）　　　　　　　　　　　　　　　
  折原操,岩橋洋平,平野茂,土方泰斗,矢口裕之,吉田貞史
  第66回応用物理学会学術講演会, Sep. 2005
• ラマン分光を用いたGaAsN混晶の光照射による構造変化の評価　　　　　　　　　　　　　　　
  矢口裕之,清水博史,森桶利和,青木貴嗣,土方泰斗,吉田貞史,宇佐美徳隆,吉田正裕,秋山英文,青木大一郎,尾鍋研太郎
  第66回応用物理学会学術講演会, Sep. 2005
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -紫外領域への拡張-　　　　　　　　　　　　　　　
  窪木亮一,覚張光一,土方泰斗,矢口裕之,吉田貞史
  第66回応用物理学会学術講演会, Sep. 2005
• 低オフ角C面SiC基板上の酸化膜の評価　　　　　　　　　　　　　　　
  土方泰斗,矢口裕之,吉田貞史,高田恭孝,小林啓介,野平博司,服部健雄
  第66回応用物理学会学術講演会, Sep. 2005
• 赤外反射分光法を用いたSiCエピ膜の電気的特性の評価　　　　　　　　　　　　　　　
  大石慎吾,土方泰斗,矢口祐之,吉田貞史
  第66回応用物理学会学術講演会, Sep. 2005
• 様々な傾斜角を有するSiC基板上の酸化膜の評価　　　　　　　　　　　　　　　
  土方泰斗,矢口裕之,吉田貞史,高田恭孝,小林啓介,野平博司,服部健雄
  第52回応用物理学関係連合講演会, 2005
• 分光エリプソメータによるSiO2/SiC界面の光学的評価 -紫外領域への拡張-　　　　　　　　　　　　　　　
  窪木亮一、覚張光一、橋本英樹、土方泰斗、矢口裕之、吉田貞史
  応用物理学会SiC及び関連ワイドギャップ半導体研究会第14回講演会, 2005
• 窒素をδドープしたGaAsの顕微フォトルミネッセンス　　　　　　　　　　　　　　　
  花島君俊,森桶利和,青木貴嗣,土方泰斗,矢口裕之,吉田貞史,吉田正裕,秋山英文,平山琢,片山竜二,尾鍋研太郎
  第52回応用物理学関係連合講演会, 2005
• 赤外反射分光法を用いたSiCエピ膜の電気的特性の評価　　　　　　　　　　　　　　　
  大石慎吾、土方泰斗、矢口裕之、吉田貞史
  応用物理学会SiC及び関連ワイドギャップ半導体研究会第14回講演会, 2005
• 赤外反射分光法を用いたSiCエピ膜の電気的特性の評価　　　　　　　　　　　　　　　
  大石慎吾,土方泰斗,矢口裕之,吉田貞史
  第52回応用物理学関係連合講演会, 2005
• RF-MBE法を用いた4H-SiC基板上へのInN/InGaN量子井戸構造の作製　　　　　　　　　　　　　　　
  折原操,北村芳広,岩橋洋平,平野茂,土方泰斗,矢口裕之,吉田貞史
  第52回応用物理学関係連合講演会, 2005
• RF-MBE growth of cubic InN films on MgO(001) substrates　　　　　　　　　　　　　　　
  Iwahashi Y., Yaguchi H., Nishimoto A., Orihara M., Hijikata Y., and Yoshida S.
  6th International Conference on Nitride Semiconductors (Bremen), 2005
• Real Time Observation of SiC Oxidation using an In-Situ Ellipsometer　　　　　　　　　　　　　　　
  Kakubari K., Kuboki R., Hijikata Y., Yaguchi H., and Yoshida S.
  International Conference on SiC and Related Materials (Pittsburg), 2005
• Photo-induced improvement of radiative efficiency and structural changes in GaAsN alloys　　　　　　　　　　　　　　　
  Yaguchi H., Morioke T., Aoki T., Shimizu H., Hijikata Y., Yoshida S., Yoshita M., Akiyama H., Usami N., Aoki D., and Onabe K.
  6th International Conference on Nitride Semiconductors (Bremen), 2005
• Off-Angle Dependence of Characteristics of 4H-SiC-Oxide Interfaces　　　　　　　　　　　　　　　
  Hijikata Y., Yaguchi H., Yoshida S., Takata Y., Kobayashi K., Nohira H. and Hattori T.
  International Conference on SiC and Related Materials (Pittsburg), 2005
• In-situ 分光エリプソメータによるSiCの酸化の実時間観察　　　　　　　　　　　　　　　
  覚張光一,窪木亮一,土方泰斗,矢口裕之,吉田貞史
  第52回応用物理学関係連合講演会, 2005
• In-situ エリプソメータによるSiC の酸化の実時間観察　　　　　　　　　　　　　　　
  覚張光一、窪木亮一、土方泰斗、矢口裕之、吉田貞史
  応用物理学会SiC及び関連ワイドギャップ半導体研究会第14回講演会, 2005
• 分光エリプソメータによるSiC 上酸化膜の初期酸化過程の観察 (IV)　　　　　　　　　　　　　　　
  覚張光一,土方泰斗,矢口裕之,吉田貞史
  第65回応用物理学会講演会, 2004
• 分光エリプソメータによるSiC の初期酸化過程の観察　　　　　　　　　　　　　　　
  覚張光一,土方泰斗,矢口裕之,吉田貞史
  2004
• 低窒素濃度GaPN混晶のフォトルミネッセンス　　　　　　　　　　　　　　　
  青木貴嗣,森桶利和,土方泰斗,矢口裕之,吉田貞史,張保平,三吉靖郎,尾鍋研太郎
  第65回応用物理学会講演会, 2004
• 高エネルギー分解能光電子分光による4H-SiC(000-1)面上酸化膜の評価　　　　　　　　　　　　　　　
  土方泰斗,矢口裕之,吉田貞史,高田恭孝,小林啓介,辛埴,野平博司,服部健雄
  2004
• レーザー照射によるGaAsN混晶の発光効率向上の窒素濃度依存性　　　　　　　　　　　　　　　
  森桶利和,青木貴嗣,呉智元,吉田正裕,秋山英文,土方泰斗,矢口裕之,吉田貞史,青木大一郎,尾鍋研太郎
  第65回応用物理学会講演会, 2004
• ラマン分光法によるInAsN混晶の評価　　　　　　　　　　　　　　　
  本村寛,土方泰斗,矢口裕之,吉田貞史,飛田聡,西尾晋,片山竜二,尾鍋研太郎
  第65回応用物理学会講演会, 2004
• RF-MBE法を用いた立方晶InNの結晶成長 (III)　　　　　　　　　　　　　　　
  岩橋洋平,北村芳広,多田宏之,折原操,土方泰斗,矢口裕之,吉田貞史
  第65回応用物理学会講演会, 2004
• RF-MBE法を用いた4H-SiC基板上へのInGaN 結晶成長　　　　　　　　　　　　　　　
  折原操,北村芳広,岩橋洋平,多田宏之,土方泰斗,矢口裕之,吉田貞史
  第65回応用物理学会講演会, 2004
• RF-MBE法を用いた4H-SiC(0001)基板上へのInN の結晶成長　　　　　　　　　　　　　　　
  北村芳広,岩橋洋平,多田宏之,折原操,土方泰斗,矢口裕之,吉田貞史
  第65回応用物理学会講演会, 2004
• RF-MBEによるMgO(001)基板上への立方晶GaN の成長　　　　　　　　　　　　　　　
  多田宏之,北村芳広,岩橋洋平,折原操,土方泰斗,矢口裕之,吉田貞史
  第65回応用物理学会講演会, 2004
• Growth of high-quality hexagonal InN on 3C-SiC (001) by molecular beam epitaxy　　　　　　　　　　　　　　　
  Yaguchi H., Kitamura Y., Nishida K., Iwahashi Y., Hijikata Y. and Yoshida S.
  2004
• Epitaxial Growth of hexagonal and Cubic InN Films by Gas Source Molecular beam Epitaxy　　　　　　　　　　　　　　　
  Yoshida S., Kitamura Y., Iwahashi Y., Tada H., Orihara M., Hijikata Y. and Yaguchi H.
  2004
• Characterization of Oxide Films on SiC Epitaxial (000-1) Faces by Angle-Resolved Photoemission Spectroscopy Measurements using Synchrotron Radiation　　　　　　　　　　　　　　　
  Hijikata Y., Yaguchi H., Yoshida S., Takata Y., Kobayashi K., Shin S., Nohira H., Hattori T.
  2004
• Photoemission spectroscopy and in-situ spectroscopic ellipsometry studies on the Ar post-oxidation-annealing effects of oxide/SiC interfaces　　　　　　　　　　　　　　　
  Y. Hijikata; S. Kawato; S. Sekiguchi; H. Yaguchi; Y. Ishida; M. Yoshiawa; T. Kamiya; S. Yoshida
  Proceedings of 1st Asia-Pacific Workshop on Widegap Semiconductors, 2003
  2003 - 2003
• Miniaturization of the Fiber Optic Probe for High Frequency Ultrasonic Field and Simultaneous Measurement of Acoustic Pressure and Temperature　　　　　　　　　　　　　　　
  NIMURA Hiroshi; HIJIKATA Yasuto; NAKAMURA Kentaro
  Dec. 1999
  Dec. 1999 - Dec. 1999, Japanese
• A study on characteristics of micro-probe -A trial construction of a miniaturized optical fiber probe for high-frequency ultrasonic field measurements(III)　　　　　　　　　　　　　　　
  HIJIKATA Yasuto; NIMURA Hiroshi; NAKAMURA Kentaro
  Sep. 1999
  Sep. 1999 - Sep. 1999, Japanese

• Generation of arbitrary polarized single-photons by injection of spin electric current to a silicon carbide MOS device　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 01 Apr. 2022 - 31 Mar. 2025
  Saitama University
  Grant amount(Total)：17810000, Direct funding：13700000, Indirect funding：4110000
  Grant number：22H01517
• Elucidation of SiC-MOS interfaces by developing electronic structure calculation methods　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), 05 Apr. 2021 - 31 Mar. 2024
  Tokyo Institute of Technology
  Grant amount(Total)：42250000, Direct funding：32500000, Indirect funding：9750000
  Grant number：21H04553
• Multi-scale calculations for complex correlation appearing in SiC oxidation and its impact on electronic properties　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Grant-in-Aid for Scientific Research (A), 01 Apr. 2018 - 31 Mar. 2021
  Matsushita Yu-ichiro, Tokyo Institute of Technology
  Grant amount(Total)：41860000, Direct funding：32200000, Indirect funding：9660000
  In this project, we propose a method to identify SiC-MOS interface defects and to reduce the defects at the SiC/SiO2 interface based on first-principles calculations. In this study, two candidate defects at the SiC-MOS interface were successfully identified: one is an intrinsic defect in SiC due to the wave function at the lower end of the conduction band of SiC, and the other is a carbon-related defect precipitated at the interface. In particular, we proposed an oxide film formation method without thermal oxidation as a method to propose carbon-related defects precipitated at the interface. The experimental results showed that the density of interfacial defects could be reduced to one-tenth.
  Grant number：18H03770
  受賞ID：30040889
• Quantum state measurements of single photon sources in silicon carbide devices　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Grant-in-Aid for Scientific Research (A), 01 Apr. 2017 - 31 Mar. 2020
  Ohshima Takeshi, National Institutes for Quantum and Radiological Science and Technology
  Grant amount(Total)：43940000, Direct funding：33800000, Indirect funding：10140000
  In order to clarify the optical and spin properties of single photon sources (SPSs) in silicon carbide (SiC), and also to develop manipulation methods for those properties, a) we developed the position selective introduction method of SPSs in SiC devices and demonstrated magnetic field sensing using optically detected magnetic resonance (ODMR) in which spin manipulation is performed. b) We established basic technology on the quantum manipulation for SPSs such as spin and optical properties using operation of electronic device such as applying bias and injection of current. c) We obtained the information on the fabrication process of Nitrogen-vacancy center (NcVsi) and surface SPS of which atomic structure have not yet been identified, and also revealed the quantum properties of those SPSs.
  Grant number：17H01056
  受賞ID：30040889
• Development of an extreme environment resistive CCD using silicon carbide　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), 01 Apr. 2015 - 31 Mar. 2019
  HIJIKATA Yasuto, Saitama University
  Grant amount(Total)：16510000, Direct funding：12700000, Indirect funding：3810000
  In this study, I attempt to fabricate a CCD using SiC semiconductors that have high radiation hardness and durability under high temperature circumstances. First of all, basic principles such as a photo-response in SiC MOS capacitor and charge transfer in a MOS capacitor array have been verified. As a result, photo-responses were confirmed from irradiation at UV-green region in cubic SiC substrates as well as at UV region for hexagonal SiC substrates. MOS capacitor arrays were fabricated using photo-lithography, and I for the first time succeeded in charge transfer in SiC semiconductors. Gamma irradiation tests were carried out for SiC and Si MOS capacitors, and it was found that SiC MOS capacitors had about three orders higher gamma-ray durability compared with that of Si.
  Grant number：15H03967
• Generation and control of quantum correlated photons from atomic-layer doped semiconductors　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), 01 Apr. 2012 - 31 Mar. 2015
  YAGUCHI Hiroyuki; ONABE Kentaro; KATAYAMA Ryuji; KUBOYA Shigeyuki; HIJIKATA Yasuto; YAGI Shuhei; AKIYAMA Hidefumi, Saitama University
  Grant amount(Total)：19240000, Direct funding：14800000, Indirect funding：4440000
  We have grown nitrogen and erbium atomic-layer doped semiconductors to obtain unpolarized single photons and quantum-entangled photon pairs with highly reproducible wavelengths, which play a key role in the quantum information science. We have successfully observed completely unpolarized biexciton and exciton emission lines, which are suitable for the application to polarization-entangled photon pairs. We have quantitatively studied the temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy, and found that overlayer growth at low temperatures is effective in suppressing the surface segregation and obtaining atomic-layer doped structures.
  Grant number：24360004
• Elucidation of formation mechanism of oxidation-induced fault in silicon carbide semiconductors　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), 01 Apr. 2012 - 31 Mar. 2015
  HIJIKATA Yasuto; YAGUCHI Hiroyuki, Saitama University
  Grant amount(Total)：5460000, Direct funding：4200000, Indirect funding：1260000
  For a better understanding of oxidation mechanism of silicon carbide (SiC), 1)Profiling of oxides on SiC, 2)Photoluminescence imaging of oxidized substrates, 3)Real-time observations of SiC oxidation processes have been performed. From result 1), we for the first time succeeded in the observation of “Si emission phenomenon” during oxidation of SiC from the oxidation interface to oxide. According to result 2), we found that there were stacking faults that are deformed by oxidation and there was a possibility that faults, which are similar to “oxidation-induced stacking fault” seen in Si oxidation, were also formed in Si oxidation. From result 3), a unified SiC oxidation model was established, and the formations of interface defect were simulated in terms of interface concentration of emitted Si and C atoms.
  Grant number：24560365
• Single Photon Generation from locally doped semiconductors　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), 2009 - 2011
  YAGUCHI Hiroyuki; HIJIKATA Yasuto; ONABE Kentaro; KATAYAMA Ryuji; YAGI Shuhei; KUBOYA Shigeyuki; AKIYAMA Hidefumi, Saitama University
  Grant amount(Total)：18460000, Direct funding：14200000, Indirect funding：4260000
  We have fabricated locally doped semiconductors using atomic layer doping to realize the generation of unpolarized single photons with highly reproducible wavelengths, which is essential in the field of quantum information technology, such as quantum cryptography. We have obtained unpolarized single photons by selecting a proper face of the substrate to grow nitrogen atomic layer doped semiconductors. In addition, we have successfully observed biexcition emission from nitrogen atomic layer doped semiconductors, which leads to the generation of entangled photon pairs.
  Grant number：21360004
• Study on single photon emission utilizing isoelectronic traps　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), 2005 - 2006
  YAGUCHI Hiroyuki; YOSHIDA Sadafumi; HIJIKATA Yasuto, Saitama University
  Grant amount(Total)：3500000, Direct funding：3500000
  Single photon emitting devices are expected to play an important role in the quantum information technology, such as quantum cryptography and quantum computing. In this study, we have studied the properties of photoluminescence due to single isoelectronic traps in nitrogen delta-doped GaAs and GaP to examine the prospect for applications to single photon emitting devices. We have optimized growth conditions to obtain nitrogen pairs with specific configurations. As a result, we have successfully observed sharp photoluminescence lines due to a limited number of isoelectronic traps within a diameter of 1 μm for nitrogen delta-doped GaAs with low nitrogen concentrations. This result shows good prospects for the single photon emitting device utilizing single isoelectronic traps. We have also observed twin photoluminescence peaks from single isoelectronic traps due to nitrogen pairs in nitrogen delta-doped GaAs. The twin photoluminescence peaks showed almost the same intensity and linear polarizations which are completely orthogonal to each other. This unique phenomenon has prospects of applications to novel optoelectronic devices. Furthermore, we have investigated the excitation power density and nitrogen concentration dependence of the changes in the radiative efficiency of GaAsN alloys to examine the mechanism of the novel phenomenon that photoexcitation at low temperatures improves the radiative efficiency. We have found that the radiative efficiency improvement is closely related to local structural changes by using in-situ micro Raman scattering spectroscopy.
  Grant number：17560004
• テラヘルツ反射分光法による炭化珪素半導体の電気的特性の非破壊マッピング測定　　　　　　　　　　　　　　　
  2005 - 2006
  Grant amount(Total)：3600000, Direct funding：3600000
  Grant number：17760247
• Characterization of the Interfaces between IV-IV Semiconductors and Ultra-Thin Oxide films　　　　　　　　　　　　　　　
  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), 2001 - 2002
  YOSHIDA Sadafumi; HIJIKATA Yasuto; YAMAGUCHI Hiroyuki, Saitama University
  Grant amount(Total)：15300000, Direct funding：15300000
  We have used spectroscopic ellipsometry, together with photoelectron spectroscopy, to investigate the interfaces between the oxide film and SiC, structural changes in the interfaces by various kinds of heat treatment after the oxide film formation, and the correlation with their electrical properties, in order to search appropriate oxidation process good for SiC MOSFETs.
  We have developed in-situ spectroscopic ellipsometry system to acquire the knowledge for clarifying the formation process of ultra-thin oxide films on SiC and microstructure of the interfaces. It is found that the composition of the oxide film formed in the initial stage of oxidization is different from that of stoichiometric SiO_2 and that the refractive indices of the interface layers, which are larger than that of SiC and SiO_2, decrease with heat treatment. In order to make clear the relation between the refractive indices of the interfaces and interface state density, we have carried out spectroscopic ellipsometry and C-V measurements for the SiC MOS structures whose interface state density is increased by gamma ray irradiation. We have found that the refractive indices of the interface layers increase with gamma ray irradiation, which suggest that the refractive indices obtained by spectroscopic ellipsometry are closely related to the interface state density, which affects the channel mobility in SiC MOSFET. Angle-resolved x-rays photoemission spectroscopy and ultraviolet photoemission spectroscopy were performed to clarify the change of composition and bonding state at the oxide/SiC interfaces by heat treatment. In addition, we have used micro infrared reflection spectroscopy to characterize the electrical properties of SiC bulk crystals and demonstrated that the distribution of the career concentration and mobility in SiC wafers can be 〓〓〓〓sured nondestructively without electric contacts.
  This research project brings about a better understanding of the structures of oxide/SiC interfaces and reveals that spectroscopic ellipsometry is an excellent characterization technique and is applicable to monitoring tool during device processes.
  Grant number：13450120