Lattice-mismatched In/sub 0.40/Al/sub 0.60/As window layers for indium phosphide solar cells

The efficiency of indium phosphide solar cells is limited by the high surface recombination velocity (/spl sim/10/sup 7/ 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/sub 0.40/Al/sub 0.60/As 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/sup +/n cells are increased to more than 22% and 24% (AM0, 25/spl deg/C) respectively for In/sub 0.04/Al/sub 0.60/As window layer of 10 nm thickness. Comparatively little improvement is found for n/sup +/p cells.>