Staggered InGaAs/GaAsP strained layer superlattices for use in optical devices

Strained layer superlattice (SLS) structures lattice matched to GaAs, such as InGaAs/GaAsP, use thin films to meet both the strain balance and critical layer thickness (CLT) conditions. Optical absorption in the InGaAs layers will be shifted to higher energies relative to thick films due to both the quantum size effect (QSE) and compressive strain, which is an undesirable restriction. We report on a new concept for a strain balance superlattice that will allow for thicker InGaAs films and reduce the cutoff energy. The staggered strain balanced superlattice structure can improve the performance of optical detectors and solar cells.