Patent ID: 8309990

Claim:
A III-V compound semiconductor structure comprising epitaxial structures that include an integrated pair of different types of active devices, the semiconductor structure comprising: a semi-insulating substrate of a compound semiconductor III-V material; and a first compound semiconductor III-V epitaxial structure disposed on the substrate, the first epitaxial structure forming at least a portion of one of the active devices; wherein a concentration profile of dopant material in the semiconductor structure across an interface between the substrate and the first epitaxial structure decreases substantially smoothly across the interface in a direction from the first epitaxial structure toward the substrate, and continues to decrease substantially smoothly from the interface with increasing depth into the substrate despite the presence of silicon or oxygen contaminant at the interface, and wherein the interface between the substrate and the first epitaxial structure is substantially free of a second contaminant that was present, during formation of the first epitaxial structure, in a chamber in which the first epitaxial structure was formed.