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-irradiated p-channel SiC metal-oxide-semiconductor field-effect transistors containing step bunchingLee, K. K.*; Oshima, Takeshi; Oi, Akihiko*; Ito, Hisayoshi; Pensl, G.*
Japanese Journal of Applied Physics, Part 1, 45(9A), p.6830 - 6836, 2006/09
Times Cited Count：16 Percentile：51.17(Physics, Applied)no abstracts in English
Kinoshita, Akimasa*; Iwami, Motohiro*; Kobayashi, Kenichi*; Nakano, Itsuo*; Tanaka, Reisaburo*; Kamiya, Tomihiro; Oi, Akihiko; Oshima, Takeshi; Fukushima, Yasutaka*
Nuclear Instruments and Methods in Physics Research A, 541(1-2), p.213 - 220, 2005/04
Times Cited Count：27 Percentile：84.73(Instruments & Instrumentation)no abstracts in English
Oshima, Takeshi; Sumita, Taishi*; Imaizumi, Mitsuru*; Kawakita, Shiro*; Shimazaki, Kazunori*; Kuwajima, Saburo*; Oi, Akihiko*; Ito, Hisayoshi
Proceedings of 31st IEEE Photovoltaic Specialists Conference and Exhibition (PVSC-31), p.806 - 809, 2005/00
no abstracts in English
Imaizumi, Mitsuru*; Takamoto, Tatsuya*; Sumita, Taishi*; Oshima, Takeshi; Yamaguchi, Masafumi*; Matsuda, Sumio*; Oi, Akihiko; Kamiya, Tomihiro
Proceedings of 3rd World Conference on Photovoltaic Energy Conversion (WCPEC-3) (CD-ROM), 4 Pages, 2004/01
The radiation response of InGaP, InGaAs and Ge single junction sub-cells in the triple junction space solar cell are studied in order to develop a device simulator which predicts the End-Of-Life performance of space solar cells. InGaP top-cells show no significant difference in radiation response between under AM0 light and dark conditions during irradiation. The radiation resistance of InGaAs cell which is used as middle cell decreases with increasing In contents. The Ge cell shows lower radiation reisitance as compared to InGaP and InGaAs cells.
Sumita, Taishi*; Imaizumi, Mitsuru*; Matsuda, Sumio*; Oshima, Takeshi; Oi, Akihiko; Kamiya, Tomihiro
Proceedings of 3rd World Conference on Photovoltaic Energy Conversion (WCPEC-3) (CD-ROM), 4 Pages, 2004/01
While high beginning-of-life efficiencies are important for space solar cells, the end-of-life performance is also critical factor. Two different prediction methods, "relative damage dose" and "displacement damage dose" methods, based on analysis of ground radiation test have been produced. We report proton radiation response for triple-junction space solar cells and analyze prediction methodology for the cell radiation response using the two methods. The results show that V
degradation behavior can be predicted by taking into account a cell structure and proton penetration depth. Accurate prediction of power degradation, however, is required to determine the current-limiting sub cell after proton irradiations.
Sumita, Taishi*; Imaizumi, Mitsuru*; Matsuda, Sumio*; Oshima, Takeshi; Oi, Akihiko; Ito, Hisayoshi
Nuclear Instruments and Methods in Physics Research B, 206, p.448 - 451, 2003/05
Times Cited Count：55 Percentile：94.89(Instruments & Instrumentation)Proton irradiation effects of triple-junction (InGaP/GaAs/Ge) solar cells for space use were studied. The changes in electrical and optical properties of the solar cells irradiated with protons at energies between 20 keV and 10 MeV were examined. As the result of analyzing the relationship between proton projection range and the degradation of their properties, the largest degradation of the properties was observed when proton projection range is near the junction of GaAs sub-cells. This indicates that improvement of the radiation resistance of GaAs is necessary to enhance radiation resistance of tliple-junction solar cells.
Isoya, Junichi*; Oshima, Takeshi; Oi, Akihiko; Morishita, Norio; Ito, Hisayoshi
Nuclear Instruments and Methods in Physics Research B, 206, p.965 - 968, 2003/05
Times Cited Count：8 Percentile：50.20(Instruments & Instrumentation)no abstracts in English
Oshima, Takeshi; Imaizumi, Mitsuru*; Takamoto, Tatsuya*; Sumita, Taishi*; Oi, Akihiko; Kawakita, Shiro*; Ito, Hisayoshi; Matsuda, Sumio*
Proceedings of 5th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications, p.113 - 116, 2002/10
The effects on proton and electron irradiateions of the characteristics of InGaP/GaAs/Ge triple junction designed for terrestrial application were studied. The solar cells used in this study has a 1% In-contained GaAs middle sub-cell, and their efficiency is more than 30 % under AM1.5, which is the highest efficiency of all solar cells in the world.As the results of 1MeV-electron and 10 MeV-proton irradiation, terrestrial triple-junction sole cells were found to have the same radiation resistance as space single junction GaAs solar cells, although terrestrial triple-junction solar cells is not stronger than space triple-junction solar cells made in USA. As the result of proton energy dependence of the electrical characteristics and quantum efficiency, the strong degradation of the GaAs middle cell was observed.
Oshima, Takeshi; Lee, K. K.; Oi, Akihiko; Yoshikawa, Masahito; Ito, Hisayoshi
Materials Science Forum, 389-393, p.1093 - 1096, 2002/05
Gamma-ray irradiation effects on the electrical characteristics such as threshold voltage (V
) and channel mobility (
) for 6H-SiC MOSFETs were studied.The gate oxide of the MOSFETs were annealed in hydrogen at 700 
or steam at 800 in fabrication process to improve the initial electrical characteristics of the MOSFETs.As for the hydrogen-annealed MOSFETs,V was changed from 0.9V to 3.1 V by irradiation at 530kGy. decreased after irradiation above 60 kGy. As for the steam-annealed MOSFETs,V was changed from 2.7 to 3.3 V by irradiation at 530kGy. decreased above 180 kGy. This indicates that radiation resistance for the steam-annealed MOSFETs is higher than that for the hydrogen-annealed MOSFETs.
Oi, Akihiko; Oshima, Takeshi; Yoshikawa, Masahito; Lee, K. K.; Iwami, Motohiro*; Ito, Hisayoshi
Materials Science Forum, 389-393, p.831 - 834, 2002/05
no abstracts in English
