Large scale, high efficiency GaAs/Ge cell production

The status of GaAs/Gei (inactive germanium) solar cells is described. Production cells have shown increased efficiency, ruggedness, and other operating advantages. Production acceptance was accelerated by validation of a cell design in which the GaAs/Ge interface was rendered inactive. It was successfully demonstrated that by replacing the expensive GaAs substrates with the lower-cost Ge substrates, lot average AM0 efficiency at a load voltage, of 825 mV approaching 18% can be achieved for 4 cm×2 cm solar cells in a large-scale production environment. By changing to 2 cm×4 cm, the projected lot average AM0 efficiency at maximum power point should be approaching 19%. The best AM0 efficiency at a load voltage of 825 mV for production 4 cm×2 cm solar cells is about 19%. The projected 2 cm×4 cm GaAs/Gei solar cell AM0 efficiency at maximum power point approaches 20%, very close to a reported R&D 2 cm×2 cm cell value of 20.5%. Concurrent work is adapting the cells to give higher efficiency and to form larger, thinner cells