Design and production of extremely radiation-hard 26% InGaP/GaAs/Ge triple-junction solar cells

The authors report the design and testing of extremely radiation-hard high-efficiency large-area InGaP/GaAs/Ge triple-junction solar cells. The solar cell junctions are designed for longer minority carrier diffusion lengths after particle irradiation. The power remaining factors after 5E14 and 1E15 electrons/cm/sup 2/ 1-MeV electron radiation are 92% and 87.5%, respectively. These results are highest reported to date and are extremely desirable for electrical power design of the spacecraft. Furthermore, the InGaP/GaAs/Ge triple-junction solar cells are currently in production at EMCORE Photovoltaics. Minimum average AM0 efficiency for the large-area fight cells is 26%, with efficiencies as high as 27% demonstrated for a large number of cells.