GaInP2 and GaAs solar cells grown on Si substrate

Large size Si substrates coated with a thin layer of single crystal Ge were used to grow GaAs and GaInP2 solar cells using MOCVD. Preliminary evaluation indicated (1) both GaAs and GaInP2 were highly crystalline epi-layers, (2) quantum efficiency of GaInP2 cell on Si substrate can reach 94% of high quality GaInP2 on Ge substrate and that of GaAs cell on Si substrate can reach 83.4%, and (3) a 5000 thermal cycle test of temperature range from +170 degreesC to -100 degreesC did not damage the solar cell. These results showed that a properly prepared Ge layer on Si can relax strain and grow a high quality GaInP2 and GaAs solar cell, with a practical efficiency for space application.