Development and characterization of high-efficiency Ga0.5In0.5P/GaAs/Ge dual- and triple-junction solar cells

This paper describes recent progress in the characterization, analysis, and development of high-efficiency, radiation-resistant Ga0.5In0.5P/GaAs/Ge dual-junction (DJ) and triple-junction (TJ) solar cells, DJ cells have rapidly transitioned from the laboratory to full-scale (325 kW/year) production at Spectro-lab. Performance data for over 470 000 large-area (26.93 cm(2)), thin (140 mu m) DJ solar cells groan on low-cost, high-strength Ge substrates are shown, Advances in next-generation triple-junction Ga0.5In0.5P/GaAs/Ge cells with an active Ge component cell are discussed, giving efficiencies up to 26.7% (21.65-cm(2) area), AM0, at 28 degrees C, Final-to-initial power ratios P/P-0 of 0.83 were measured for these n-on-p DJ and TJ cells after ir radiation with 10(15) 1-MeV electrons/cm(2). Time-resolved photoluminescence measurements are applied to double heterostructures grown with semiconductor lavers and interfaces relevant to these multijunction solar cells, to characterize surface and bulk recombination and guide further device improvements, Dual- and triple-junction Ga0.5In0.5P/GaAs/Ge cells are compared to competing space photovoltaic technologies, and found to offer 60-75% more end-of-life power than high-efficiency Si cells at a nominal array temperature of 60 degrees C.