Large area space solar cells-Si or GaAs

The authors review the status of both large-area silicon and GaAs cells and discuss how GaAs cells may be competitive with silicon cells. It is noted that significant advances have been made in producing silicon solar cells with good efficiencies and large areas. Development cells have shown even higher efficiencies. GaAs solar cells have been in continuous production since 1984. Metalorganic chemical vapor deposition (MOCVD)-grown GaAs on Ge substrates have been in production since mid-1989, and the efficiency has been improving steadily. Large-area (up to 6×6 cm²) GaAs/Ge cells with thicknesses down to 3.5 mil are available in limited quantity. The thin GaAs/Ge cell process is being scaled-up for higher productivity. Current work is directed towards larger cells, possibly with wraparound or wrapthrough contacts. It is pointed out that production experience with GaAs/Ge solar cells is accumulating and cell costs are decreasing steadily. At system levels, GaAs/Ge cells can compare favorably with silicon cells in cost and performance