Patent ID: 8217480

Claim:
An absorber layer for a barrier infrared photodetector comprising: a substrate formed of a substrate material having a substrate lattice constant; a superlattice disposed on the substrate, said superlattice being formed from a plurality of supercells, each of said supercells being formed from a plurality of layers of at least InAsSb and at least one semiconductor material selected from the group consisting of InAs, InAsSb, and InGaAs, and each layer being defined by a layer thickness such that each supercell has a period defined by the combined thicknesses of the plurality of layers in said supercell; wherein the combination of semiconductor materials in each layer of each supercell are chosen to yield a configuration substantially strain balanced to the substrate lattice constant; wherein the thickness of each of the layers does not exceed a critical thickness above which the layer is no longer coherently strained; and wherein the energy band gap structure of each supercell including the band gap, conduction band edge and the valence band edge of the superlattice depends on the structure of the supercell.