First Principles Study of Collector Transit Time Modulation in Double Heterojunction Bipolar Transistors

Velocity overshoot in heterojunction bipolar transistors has long been recognized to significantly reduce collector signal delay below that predicted under the assumption of a constant saturated electron velocity [1], [2]. This phenomenon has proven critical for high frequency operation of InP DHBTs which has resulted in cutoff frequencies above 1 THz [3]. In order to better understand the operation of these devices, we further explore the microscopic electron dynamics through simulation. We report modulated collector signal delay results from static and dynamic full band ensemble Monte Carlo simulation of a 300nm InGaAs/InP DHBT with a 300 nm collector.