Application of InAlAs/GaAs superlattice alloys to GaAs solar cells

AlGaAs/GaAs solar cells are typically characterized as having relatively high interface recombination velocities at the heteroface. Some of the factors influencing the design of solar cell window layers are examined, and the effect of substituting InAlAs/GaAs superlattice alloys and InAlAs bulk alloys in place of AlGaAs is considered. Potential advantages are reduced surface recombination at the heterojunction, reduced thermionic emission into the window layer, thinner window layers, and reduced absorption in the window layer. Theoretical models predict a lower effective surface recombination velocity and a smaller acceptor activation energy for superlattice alloys. Experimental absorption data show that superlattice alloys have a lower absorption coefficient at short wavelengths near the UV roll off