Evaluation of strained InAlAs as a window layer for wide bandgap materials lattice matched to InP

In order to be considered a viable option as a window layer, a number of requirements must be met. These include high transparency, small valence band offset, high conduction band offset, low surface recombination velocity, ability to be passivated in air, and availability of a selective etchant with the contact layer. In this paper, we demonstrate that strained In_0.3Al_0.7As meets all of these requirements for widebandgap, lattice-matched InAlAs grown on InP substrates. We expect the results to be applicable to the InAlAsSb system which could enable triple junction photovoltaic devices with record efficiencies.