High-efficiency concentrator cells from GaAs on Si

The achievement of cell inefficiencies of 21.3% ( approximately 200X, AM1.5D) for a GaAs-on-Si solar cell, and 27.6% ( approximately 200X, AM1.5D) for a GaAs homoepitaxial solar cell is reported. The value of 21.3% represents the highest efficiency reported for a monolithically grown GaAs-on-Si solar cell, while 27.6% is the highest confirmed value for any single-junction solar cell without the use of a prismatic cover. The GaAs-on-Si cell uses GaAs layers, grown by metalorganic chemical vapor deposition (MOCVD), with a defect density of approximately 2*10/sup 7/ cm/sup -2/. High efficiency in the heteroepitaxial cell has been achieved by careful design of the cell layers, taking into account the actual properties of this highly defected material.<
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