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Oshima, Takeshi; Onoda, Shinobu; Iwamoto, Naoya; Kojima, Kazutoshi*; Kawano, Katsuyasu*
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.175 - 178, 2008/12
The reduction of Charge Collection Efficiency (CCE) in silicon carbide (SiC) diodes due to 
-ray, 1MeV electron, and 65MeV proton irradiations is discussed. The pn junction diodes were fabricated on SiC epitaxial layers using hot implantation. The transient currents induced by ion beam were measured using Transient Ion Beam Induced Current (TIBIC) measurement systems. The CCE are estimated from the integration of the transient current. The diodes were irradiated with either -rays, electrons at 1MeV, or protons at 65 MeV to create damage in the diodes. The CCE in the irradiated diodes was also measured. The results obtained in these measurements were evaluated using a concept of Non Ionizing Energy Loss (NIEL).
Saito, Yuichi; Yokota, Wataru; Nara, Takayuki; Agematsu, Takashi; Okumura, Susumu; Uno, Sadanori; Ishibori, Ikuo; Kurashima, Satoshi; Yoshida, Kenichi; Yuyama, Takahiro; et al.
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.95 - 98, 2008/12
Walters, R. J.*; Harris, R. D.*; Imaizumi, Mitsuru*; Lorentzen, J. R.*; Messenger, S. R.*; Tischler, J. G.*; Oshima, Takeshi; Sato, Shinichiro; Sharps, R. P.*; Fatemi, N. S.*
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.105 - 108, 2008/12
The performance of triple junction InGaP/GaAs/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out 
at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements and quantum efficiency measurements. The low temperature irradiations caused substantial degradation that differs in some ways from that seen after room temperature irradiations. The short circuit current degrades more at low temperature while the open circuit voltage degrades more at room temperature. A room temperature anneal after the low temperature irradiation produced a substantial recovery in the degradation.
Imaizumi, Mitsuru*; Toyota, Hiroyuki*; Shimada, Takanobu*; Ogawa, Hiroyuki*; Tajima, Michio*; Hisamatsu, Tadashi*; Nakamura, Kazuyo*; Takamoto, Tatsuya*; Sato, Shinichiro; Oshima, Takeshi
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.127 - 130, 2008/12
Results of our study of effects of high-light-intensity and high-temperature conditions (HIHT) on the output performance of an InGaP/GaAs/Ge triple-junction solar cell are described herein. The HIHT conditions are adjusted for spacecraft environments expected for a Venus mission (Planet-C) and a Mercury mission (MMO) to be undertaken by the Japan Aerospace Exploration Agency (JAXA). Measurements of current-voltage characteristics under high light intensity for wide range of cell temperatures exhibit a kinked pattern at 0 current at +200
C. The thermal cycle test results for bare cells with a wide temperature range show no output performance degradation. Continuous operation tests of 3J cells under HIHT conditions reveal gradual current output degradation, implying that solar panel design should address decreased output specifically.
Fumon, Takashi*; Kobayashi, Ippei*; Oshima, Takeshi; Sato, Shinichiro; Okuda, Shuichi*; Taniguchi, Ryoichi*; Iwase, Akihiro*
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.203 - 206, 2008/12
We developed an apparatus for electron irradiation and in-situ current-voltage (I-V) characteristics measurements for space solar cells. The apparatus was interfaced to an electron linear accelerator at Radiation Research Center of Osaka Prefecture University. By using this apparatus, the electron irradiation with the energies from 6 MeV to 12 MeV can be performed at various temperatures from -196 C to 100 C. In-situ I-V characteristic measurements are also possible at the temperature from -196 C to 100 C. As a first demonstration using this apparatus, we performed two experiments. First, I-V characteristics of a Si solar cell were measured at room temperature and at low temperature. Secondly, the Si solar cell was irradiated with 10 MeV electrons and I-V characteristics were measured at room temperature. The experimental result was compared with those for 1 MeV electron irradiation and 10 MeV proton irradiation.
Sato, Shinichiro; Imaizumi, Mitsuru*; Oshima, Takeshi
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.211 - 214, 2008/12
Degradation modeling of triple-junction (3J) solar cell due to proton and electron irradiation is performed with the use of a one dimensional optical device simulator, PC1D. By fitting external quantum efficiencies of the 3J solar cells degraded by proton or electron irradiation, the short-circuit current (
) and open-circuit voltage (
) are simulated. These simulated values are in good accordance with the experimental data. In this modeling, carrier removal rate of base layer (
) and the damage coefficient of minority carrier diffusion length (
) in each sub-cell are considered as radiation degradation parameters. NIEL (Non-Ionizing Energy Loss) analysis for both radiation degradation parameters is discussed. The radiation degradation of a 3J solar cell can be predicted from correlativity between NIEL and both radiation degradation parameters.
Morioka, Chiharu*; Imaizumi, Mitsuru*; Sato, Shinichiro; Oshima, Takeshi; Kibe, Koichi*
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.215 - 218, 2008/12
Radiation resistance of (Al)InGaP solar cells was examined in this study. The epitaxial structure, such as aluminum contents or carrier concentration (CC) in the base layer, is varied, whereas the base layer thickness is maintained at 1 
m. The cells are irradiated with 3 MeV protons up to the fluence of 1
10
/cm
. Remaining factors of short-circuit current and open-circuit voltage show no significant difference between Al
In
Ga
P and InGaP cells. The graded CC structure in the base layer is ineffective to improve radiation resistance in the case of (Al)InGaP cells with a thick base layer, which implies that radiation degradation is not primarily attributable to the decrease in minority-carrier diffusion length.
Abo, Satoshi*; Mokuno, Yoshiaki*; Kinomura, Atsushi*; Onoda, Shinobu; Hirao, Toshio; Oshima, Takeshi; Iwamatsu, Toshiaki*; Takai, Mikio*
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.183 - 186, 2008/12
no abstracts in English
Iwamoto, Naoya; Onoda, Shinobu; Oshima, Takeshi; Kojima, Kazutoshi*; Kawano, Katsuyasu*
Proceedings of the 8th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-8), p.191 - 194, 2008/12
no abstracts in English