High radiation tolerant GaAs on Si substrate for space solar cell

GaAs-on-Si solar cell has high potential for space applications because Si substrate is low-cost, lightweight and large-area. We have studied the radiation effects of high-energy electron (1 MeV, fluences of 1/spl times/10/sup 13/, 1/spl times/10/sup 14/, 1/spl times/10/sup 15/ an 1/spl times/10/sup 16/ cm/sup -2/) on GaAs layers on Si and GaAs substrates grown by MOCVD. After the irradiation, a decrease in the barrier height and an increase in the ideality factor of Schottky diodes were observed for diodes on GaAs substrate, but there are no considerable changes in diodes on Si substrate. The number of trap level increases more in case of GaAs/GaAs compared with GaAs/Si. The degradation of PL intensity and the increase on deep level concentration for GaAs on Si substrate are lower than those of GaAs on GaAs. These experimental results suggest that GaAs solar cell on Si substrate has higher radiation resistance compared with GaAs solar cell on GaAs substrate under 1 MeV electron irradiation.