Lattice-mismatched In0.40Al0.60As window layers for indium phosphide solar cells

The efficiency of indium phosphide solar cells is limited by the high surface recombination velocity (~10⁷ cm/s). This might be reduced by a wide-bandgap window layer. In this work the authors calculate the performance of InP solar cells with wide-bandgap (1.8 eV) lattice-mismatched In_0.40Al_0.60As as a window layer. As the required window layer is less than the critical layer thickness, growth of strained (pseudomorphic) layers without interfacial misfit dislocations should be possible. Calculations using the PC-lD numerical code have shown that the efficiencies of baseline and optimized p⁺n cells are increased to more than 22% and 24% (AM0, 25°C) respectively for In_0.04Al_0.60As window layer of 10 nm thickness. Comparatively little improvement is found for n⁺p cells