Patent ID: 8193523

Claim:
A device, comprising: a lower barrier region comprising a large band gap material; a quantum well channel region comprising germanium on the lower barrier region; an upper barrier region comprising a large band gap material on the quantum well region; a spacer region on the quantum well channel region; an etch stop region on the spacer region, the etch stop region comprising silicon and being substantially free from germanium; a gate dielectric on the etch stop region; a gate electrode on the gate dielectric; and a first contact stack to one side of the gate electrode, and on the lower barrier region, spacer region, and etch stop region, the first contact stack comprising: an upper spacer region comprising silicon germanium on the etch stop region; a doped region on the upper spacer region, the doped region comprising silicon germanium doped with boron; wherein the upper barrier region is part of the first contact stack; and a contact region on the upper barrier region.