SiGe-Base Bipolar Transistors for Cryogenic BiCMOS Applications

We demonstrate that the cryogenic (e.g., 77K=LNT) properties of SiGe-base heterojunction bipolar transistors and circuits are sufficiently advanced to warrant a serious consideration of the merits of cryogenic BiCMOS technologies for future LNT computer applications. In this paper we review the features of epitaxial SiGe-base bipolar technologies which make them particularly Suitable for LNT operation, examine the DC and dynamic properties of SiGe-base transistors operating at low temperatures, highlight the profile design constraints unique to the LNT environment, and discuss future research directions and opportunities.