Patent ID: 8354695

Claim:
A semiconductor device comprising: a semiconductor substrate; a low energy band-gap region over the semiconductor substrate; a gate dielectric over the low energy band-gap region; a gate electrode over the gate dielectric; a first and a second source/drain region on opposing sides of the low energy band-gap region, wherein the first and the second source/drain regions have a higher band-gap than the low energy band-gap region, and wherein the first and the second source/drain regions are of opposite conductivity types; a first source/drain extension region between and adjoining the low energy band-gap region and the first source/drain region, wherein the first source/drain extension region is of a same conductivity type as the first source/drain region; and a second source/drain extension region between and adjoining the low energy band-gap region and the second source/drain region, wherein the second source/drain extension region is of a same conductivity type as the second source/drain region, and wherein each of the first and the second source/drain extension regions comprises at least a portion having a band-gap lower than a band-gap of the first and the second source/drain regions.