Patent ID: 7633083

Claim:
A metamorphic semiconductor device comprising: a substrate; a semiconductor device supported by the substrate; and metamorphic buffer layers between the substrate and the semiconductor device, at least some of the metamorphic buffer layers forming two or more superlattice structures, wherein each superlattice structure comprises digital alloy layers and all of the digital alloy layers within each superlattice structure comprise an Al 1-x In x Sb sublayer and an Al 1-y In y Sb sublayer with x≠y; within a superlattice structure of the superlattice structures, the thicknesses of the Al 1-x In x Sb sublayer and the Al 1-y In y Sb sublayer vary monotonically across the superlattice structure; and the substrate has a first lattice constant, a device interface layer of the metamorphic buffer layers has a second lattice constant of between approximately 6.1 and 6.35 angstroms that is matched to a lattice constant of the semiconductor device, and the first lattice constant is significantly smaller than the second lattice constant.