HIGH-EFFICIENCY (GREATER-THAN 20-PERCENT-AMO) GAAS SOLAR-CELLS GROWN ON INACTIVE-GE SUBSTRATES

To provide high-efficiency, large-area, and lighter solar cells, gallium-arsenide (GaAs) cells have been grown on Ge substrates. The growth conditions used for several years of development of GaAs/Ge cells made the GaAs/Ge interface active, and this led to reports of erroneously high efficiencies, and to several operating problems. Here we report results showing successful formation of high-efficiency GaAs cells (over 20%, air mass zero (AMO)) grown on inactive-Ge substrates under production conditions. The growth conditions varied considerably from those previously considered essential for good-quality heteroepitaxial growth. This work opens the way for near-future implementation of large-area, lightweight, high-efficiency solar cells on spacecraft arrays. © 1990 IEEE