High Frequency Performance of SiGeC HBTs with Selectively & Non-Selectively Grown Collector

Abstract

Two high-frequency heterojunction bipolar transistor (HBT) architectures based on SiGeC have been fabricated and characterized. Different collector designs were applied either by using selective epitaxial growth doped with phosphorous or by nonselective epitaxial growth doped with arsenic. Both designs have a nonselectively deposited SiGeC base doped with boron and a poly-crystalline emitter doped with phosphorous. Both HBT designs exhibit similar electrical characteristics with a peak DC current gain of around 1600 and a BVCEO of 1.8V. The cut-off frequency (fT) and maximum frequency of oscillation (fmax) vary from 40–80GHz and 15–30GHz, respectively, depending on lateral design relations. Good high frequency performance for a device with a selectively grown collector is demonstrated for the first time.