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Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Progress in Photovoltaics; Research and Applications, 21(7), p.1499 - 1506, 2013/11
Times Cited Count：6 Percentile：26.92(Energy & Fuels)Proton degradation behaviors of hydrogenated amorphous silicon (a-Si:H) solar cells irradiated with protons at 331 K are compared with that at 298 K (room temperature). Variations with time in the post-irradiation electrical properties are also investigated. It is found that the radiation degradation of the electrical properties at 331 K is significantly smaller than that at room temperature. Also, all the electrical properties (short-circuit current, open-circuit voltage, output maximum, and fill factor) recover with time after irradiation even at room temperature. The characteristic time of thermal annealing of short-circuit current is larger as the temperature is higher. These results indicate that temperature during irradiation and elapsed time from irradiation to measurement is an important parameter for radiation degradation of a-Si:H solar cells. Therefore, these parameters should be controlled in conducting the ground radiation tests.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Journal of Non-Crystalline Solids, 358(17), p.2039 - 2043, 2012/09
Times Cited Count：5 Percentile：31.14(Materials Science, Ceramics)Electrical conductivity variations of undoped, n-type and p-type hydrogenated amorphous silicon (a-Si:H) thin films irradiated with various energy protons are systematically investigated in this study. Dark conductivity (DC) and photoconductivity (PC) of the undoped samples increased at first due to proton irradiation and then decrease dramatically with increasing proton fluence. However, increased PC was metastable and gradually decreased with time. Similar results were observed in the n-type a-Si:H, whereas the monotonic decrease was observed in the p-type one. The degrees of the DC and the PC decreases became lower as the irradiated proton energy was higher. The increases of both DC and PC are attributed to the temporal donor like center generation, although the additional proton irradiation decrease both the DC and PC by the accumulation of radiation-induced defects, which are act as deep traps and compensate carriers.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Nuclear Instruments and Methods in Physics Research B, 286, p.29 - 34, 2012/09
Times Cited Count：8 Percentile：52.49(Instruments & Instrumentation)Electric conductivity variations of undoped hydrogenated amorphous silicon (a-Si:H) semiconductors induced by swift protons are investigated. The results show that the conductivity drastically increases at first and then decreases on further irradiation. The conductivity enhancement observed only in the low fluence regime lasts for a prolonged period of time when proton irradiation stops in this fluence regime. On the other hand, the photosensitivity has a minimum value around the conductivity peak. This fact indicates that non-equilibrium carriers do not play a dominant role in the electric conduction in this fluence regime. It is found that the anomalous conductivity enhancement is dominated by donor center generation in the low fluence regime. At higher fluences the variation in electric conductivity becomes dominated by non-equilibrium carriers as the generated donor centers disappear. This is a general interpretation of radiation induced conductivity in semiconductors.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Nuclear Instruments and Methods in Physics Research B, 285, p.107 - 111, 2012/08
Times Cited Count：6 Percentile：43.52(Instruments & Instrumentation)Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Applied Physics Express, 4(6), p.061401_1 - 061401_3, 2011/06
Times Cited Count：9 Percentile：38.03(Physics, Applied)Seebeck coefficient variations of undoped hydrogenated amorphous silicon (a-Si:H) semiconductors due to swift proton irradiation were investigated using an in-situ thermoelectric power measurement system. Undoped a-Si:H irradiated with 3.0 MeV protons at a fluence regime of 3.1
10
- 5.010
/cm
showed a negative Seebeck coefficient although the Seebeck effect was not observed at fluences above 5.310
/cm. These results suggest that donor like centers are generated by low fluence proton irradiation, whereas the donor centers are compensated by radiation-induced defects or themselves disappear after high fluence proton irradiation. These effects decay with time, giving the donor centers a temporal nature.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Proceedings of 37th IEEE Photovoltaic Specialists Conference (PVSC-37) (CD-ROM), p.001615 - 001619, 2011/06
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Proceedings of 9th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-9), p.183 - 186, 2010/10
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Journal of Non-Crystalline Solids, 356(41-42), p.2114 - 2119, 2010/09
Times Cited Count：13 Percentile：57.27(Materials Science, Ceramics)Photoconductivity (PC) variations of device-grade a-Si:H thin films due to proton irradiation are investigated in this paper. We performed in-situ measurements of the PC variations induced by 0.10, 1.0 and 10 MeV proton irradiations. The irradiation initially caused an increase in PC in all sample. However, continued irradiation resulted in a dramatic decrease as the irradiation fluence increased. The results obtained in this study suggest that the PC increment is caused not by accumulation of displacement damage. The results of the temperature dependence of PC for a-Si:H before and after 10 MeV proton irradiation showed that such a proton-induced PC increment consisted of two components: one thermally stable and one metastable. The thermally metastable component disappeared in the temperature region of 300 to 340 K. On the contrary, radiation-induced defects were annealed above 340 K.
Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
Proceedings of 35th IEEE Photovoltaic Specialists Conference (PVSC-35) (CD-ROM), p.002620 - 002624, 2010/06
Times Cited Count：2 Percentile：71.41(Energy & Fuels)Sato, Shinichiro; Sai, Hitoshi*; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*; Oshima, Takeshi
Proceedings of 34th IEEE Photovoltaic Specialists Conference (PVSC-34) (CD-ROM), p.002354 - 002358, 2009/06
Photoconductivity (PC) variations of a-Si:H thin films irradiated with 0.10, 1.0 or 10 MeV protons were investigated. According to the results, the PC values of all samples once increased and after that decreased dramatically. In order to obtain the knowledge about the anomalous PC increment, time dependence of the PC value increased by 10 MeV proton irradiation was also investigated. As a result, even the PC value after 270 hours was over twice higher than that before the irradiation, though the PC values decreased with time. However, the PC value became almost equivalent to the PC before the proton irradiation by applying light-soaking. These results mean that the anomalous PC increment is metastable.
Ugachi, Hirokazu; Nakano, Junichi; Nemoto, Yoshiyuki; Kondo, Keietsu; Miwa, Yukio; Kaji, Yoshiyuki; Tsukada, Takashi; Kizaki, Minoru; Omi, Masao; Shimizu, Michio
JAEA-Conf 2006-003, p.253 - 265, 2006/05
Irradiation assisted stress corrosion cracking (IASCC) is one of the critical concerns when stainless steel components have been in service in the light water reactors (LWRs) for a long period. In general, IASCC can be reproduced on the materials irradiated over a certain threshold fluence level of fast neutron by the post-irradiation examinations (PIEs) at hot laboratories. On the other hand, recently in the Japanese boiling water reactor (BWR) power plants, many incidents of stress corrosion cracking (SCC) of structural material such as the reactor core shrouds and primary loop recirculation (PLR) system piping were reported. In order to investigate the cause of SCC, PIEs at hot laboratories were carried out on the sample material extracted from BWR power plants. SCC studies require various kind of PIE techniques, because the SCC is caused by a complicated synergistic effects of stress and chemical environment on material that suffered degradations by irradiation and/or thermal aging. In this paper, we describe the PIE techniques adopted recently for our SCC studies, especially the crack growth measurement, uniaxial constant load (UCL) tensile test method, in-situ observation during slow strain rate test (SSRT) and several metallurgical test techniques using the FEtype transmission electron microscopy (FE-TEM), focused ion beam (FIB) processing technique, three Dimensional Atom Probe (3DAP) analysis and atomic force microscopy (AFM).
Sato, Shinichiro; Sai, Hitoshi*; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*; Oshima, Takeshi
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Sato, Shinichiro; Sai, Hitoshi*; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*; Oshima, Takeshi
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-ray beam, 1; Facility design and R&D statusHajima, Ryoichi; Hayakawa, Takehito; Kikuzawa, Nobuhiro; Shizuma, Toshiyuki; Nishimori, Nobuyuki; Nagai, Ryoji; Sawamura, Masaru; Kawase, Keigo; Kosuge, Atsushi; Tateno, Ryo; et al.
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Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
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Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
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Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
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Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
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Sato, Shinichiro; Sai, Hitoshi*; Oshima, Takeshi; Imaizumi, Mitsuru*; Shimazaki, Kazunori*; Kondo, Michio*
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Hasegawa, Noboru*; Nishikino, Masaharu*; Mikami, Katsuhiro*; Okada, Hajime*; Kondo, Shuji*; Kawachi, Tetsuya*; Shimada, Yoshinori*; Kurahashi, Shinri*; Kitamura, Toshiyuki*; Kotyaev, O.*; et al.
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