Development of a high efficiency metamorphic triple-junction 2.1 eV/1.6 eV/1.2 eV AlGaInP/InGaAsP/InGaAs space solar cell

We report our progress in the development of a high efficiency metamorphic triple-junction tandem solar cell that is predicted, on the basis of modeling calculations, to have a maximum practical room temperature air mass zero one-sun (AM01S) efficiency of 31.5%, and an efficiency of 36.5% under 100 suns. Cell structures are grown using the metal organic vapor phase epitaxy (MOVPE) process. Although the three cells are lattice-matched to each other, the bottom InGaAs cell is grown on a lattice-mismatched GaAs substrate using a proprietary buffer layer. This unique buffer layer pins most defects in the vicinity of the substrate-buffer interface, allowing the growth of nearly defect-free subsequent layers.