Patent ID: 7750371
Filing Date: 2010-07-06
Classification: H01L

Abstract:
1. A semiconductor structure comprising: a first semiconductor layer having a bottom surface and comprising silicon germanium and a first dopant having a first conductivity type; a second semiconductor layer below and immediately adjacent to said first semiconductor layer, said second semiconductor layer comprising silicon and a second dopant having a second conductivity type different from said first conductivity type; and a third semiconductor layer below and immediately adjacent to said second semiconductor layer, wherein none of said first semiconductor layer, said second semiconductor layer and said third semiconductor layer are carbon-doped, wherein said second semiconductor layer has a top surface adjacent to said bottom surface and comprises a diffusion region at said top surface, wherein said diffusion region comprises said first dopant and said second dopant, and wherein said top surface comprises approximately no defects such that a peak concentration of said first dopant in said first semiconductor layer adjacent to said bottom surface is at least 100 times greater than a concentration of said first dopant in said diffusion region of said second semiconductor layer.