Structure for eliminating collector-base band gap discontinuity in an HBT

Abstract

According to one exemplary embodiment, a heterojunction bipolar transistor comprises a base having a concentration of germanium, where the concentration of germanium decreases between a first depth and a second depth in the base. According to this exemplary embodiment, the base of the heterojunction bipolar transistor further comprises a concentration of a diffusion suppressant of a base dopant, where the concentration of the diffusion suppressant decreases between a third depth and a fourth depth so as to counteract a change in band gap in the base between the first depth and the second depth. For example, the diffusion suppressant can be carbon and the base dopant can be boron. For example, the concentration of diffusion suppressant may decrease between the third depth and fourth depth so as to counteract the change in band gap at approximately the second depth.

Dependencies are inferred from the claim text.