GaAs solar cells grown on Si substrates for space use

GaAs single-junction and InGaP/GaAs multi-junction thin-film solar cells fa bricated on Si substrates have great potential for high-efficiency, low-cos t, lightweight and large-area space solar cells, Heteroepitaxy of GaAs thin films on Si substrates has been examined and high-efficiency GaAs thin-fil m solar cells with total-area efficiencies of 18.3% at AM0 and 20.0% at AM1 .5 on Si substrates (GaAs-on-Si solar cells) have been fabricated. In addit ion, 1-MeV electron irradiation damage to GaAs-on-Si cells has been studied , Tire GaAs-on-Si cells are found to show higher end-of-life efficiency tha n tire conventional GaAs cells fabricated on GaAs substrates (GaAs-on-GaAs cells) under high-fluence 1-MeV electron irradiation of more than 1 x 10(15 ) cm(-2). The first space flight to make use of them has been carried out. Forty-Eight 2 x 2 cm GaAs-on-Si cells with an average AM0 total-area effici ency of 16.9% have been evaluated in the Engineering Test Satellite No,6 (E TS-VI), The GaAs-on-Si cells have been demonstrated to be more radiation-re sistant in space than GaAs-on-GaAs cells and 50, 100 and 200-mum-thick Si c ells, These results show that tire GaAs-on-Si single-junction and InGaP/GaA s-on-Si multi-junction cells have great potential for space applications. C opyright (C) 2001 John Wiley & Sorts, Ltd.