InGaP/InGaAs/Ge high concentration solar cell development at Emcore

Results from the Emcore triple junction (3J) terrestrial concentrator cell development program are presented. The cell is intended for use at concentrations equal to or exceeding 500/spl times/ geometrical. Leveraging our 3J space cell we have redesigned the emitter/grid structure, the tunnel diode interconnects, and top cell base thickness for use under concentrated terrestrial illumination. We have achieved a conversion efficiency of 32.8% (low AOD spectrum) at 165/spl times/. Methods for achieving still higher efficiencies are discussed, including the development of a metamorphic 3J cell. We have grown and characterized InGaAs metamorphic materials on Ge to be used as virtual substrates in a metamorphic 3J cell. The metamorphic InGaAs material has photoluminescence decay times characteristic of nearly radiatively limited material.