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Sato, Shinichiro; Beernink, K.*; Oshima, Takeshi
Japanese Journal of Applied Physics, 54(6), p.061401_1 - 061401_6, 2015/06
Times Cited Count：4 Percentile：20.07(Physics, Applied)Performance degradation and immediate recovery of a-Si/a-SiGe/a-SiGe triple-junction solar cells due to irradiation of silicon ions, electrons, and protons are investigated. Significant recovery is always observed independent of radiation species and temperature. It is shown that the characteristic time, which is obtained by analyzing the short-circuit current annealing behavior, is an important parameter for practical applications in space. In addition, the radiation degradation mechanism is discussed by analyzing the energy loss process of incident particles (ionizing energy loss: IEL, and non-ionizing energy loss: NIEL) and their relative damage factors. It is determined that ionizing dose is the primarily parameter for electron degradation whereas displacement damage dose is the primarily parameter for proton degradation. The impact of "radiation quality effect" has to be considered to understand the degradation due to Si ion irradiation.
Sato, Shinichiro; Beernink, K.*; Oshima, Takeshi
IEEE Journal of Photovoltaics, 3(4), p.1415 - 1422, 2013/10
Times Cited Count：2 Percentile：9.84(Energy & Fuels)Electrical performance degradation of a-Si/a-SiGe/a-SiGe triple-junction solar cells due to irradiation of protons with different energies and their performance recovery at room temperature (RT) just after irradiation are reported. The current-voltage characteristics are measured 
, and the results show that all the parameters recover with time after proton irradiation is stopped. The degradation is scaled by a unit of displacement damage dose independent of proton energy, indicating that the proton-induced degradation is mainly caused by the displacement damage effects. By analyzing the quantum efficiency variations due to irradiation, it is clarified that the top subcell recovers more markedly at RT than the other subcells, and the recovery of the middle cell is less pronounced.
Sato, Shinichiro; Beernink, K.*; Oshima, Takeshi
Proceedings of 38th IEEE Photovoltaic Specialists Conference (PVSC-38) (CD-ROM), p.002856 - 002861, 2012/00
The electrical performance degradation of a-Si/a-SiGe/a-SiGe triple-junction solar cells due to irradiation of protons with different energies and their performance recovery at room temperature just after irradiation are investigated. It was shown that the degradation behavior depended on incident proton energies. It was also shown that all the parameters (short-circuit current, open-circuit voltage, and fill factors) recovered with time after proton irradiation was stopped. In particular, the short-circuit current intensively recovered. This is due to the carrier diffusion length increase which is based on room temperature annealing of radiation defects.
