A Closed-Form Solution for the Low-Current Collector Transit Time in Group IV and Group III-V HBTs

In certain types of heterojunction bipolar transistors (HBTs), the carrier transit time associated with the base-collector (BC) space-charge region constitutes a significant contribution to the total transit time. In many compact models, the low-current BC transit time is lumped in with the total low-current transit time and often assumed to be constant-dependent only on the collector width and ma...