Weak avalanche multiplication in SiGe heterojunction bipolar transistors on thin film silicon-on-insulator

In this paper, we propose an analytical avalanche multiplication model for the next generation of SiGe siliconon-insulator (SOI) heterojunction bipolar transistors (HBTs) and consider their vertical and lateral impact ionizations for the first time. Supported by experimental data, the analytical model predicts that the avalanche multiplication governed by impact ionization shows kinks and the impact ionization effect is small compared with that of the bulk HBT, resulting in a larger base-collector breakdown voltage. The model presented in the paper is significant and has useful applications in the design and simulation of the next generation of SiGe SOI BiCMOS technology.