Thermal-Avalanche Interacting Behavior Of Algaas/Gaas Multi-Emitter Finger Heterojunction Bipolar-Transistors

A theoretical study on the heterojunction bipolar transistor (HBT) avalanche characteristics is presented, and an empirical model to describe the observed HBT behavior developed. It is found that using the impact ionization mechanism alone cannot fully explain the small-geometry HBT avalanche behaviour, and the thermal effect needs to be included due to the elevated temperature in such operation. The model compares favorably with experimental data measured from a 6-emitter finger HBT