Advances in production MBE grown GaInP/GaAs cascade solar cells

GaInP/GaAs cascade solar cells with varying top cell base layer thickness were grown by production solid source molecular beam epitaxy (MBE). The MBE growth was optimized with special control over growth related defects resulting in a beginning of life conversion efficiency of 23.2% for a 2/spl times/2 cm/sup 2/ solar cell. Consistent results were obtained with a balloon calibration. An end of life efficiency of 19.8% and power remaining factor of 0.91 were obtained for these cells after 10/sup 15/ cm/sup -2/ 1 MeV electron irradiation. The good radiation resistance was attributed to the GaInP top cell dominated degradation and graded doping profiles of the top cell.