On the frequency limits of SiGe HBTs for TeraHertz applications

Abstract

We report record fmax for a silicon-based transistor, and the first combined set of fT + fmax above one-terahertz for silicon-germanium heterojunction bipolar transistors (SiGe HBTs). Peak f max of 618 GHz and fT of 463 GHz at 4.5 K (chuck temperature) were measured for a scaled 0.12×2.5 μm2 SiGe HBT (343 / 309 GHz at 300 K), at a breakdown voltage BVCEO of 1.62 V (1.70 at 300 K), yielding a record fT × BVCEO product of 750 GHz-V (510 GHz-V at 300 K). An examination of base transport in these devices at low temperatures suggests non-equilibrium effects are operative. © 2007 IEEE.