Numerical study of nonequilibrium electron transport in AlGaAs/GaAs heterojunction bipolar transistors

We have simulated numerically the dynamics of nonequilibrium electron transport in n-p-n AlGaAs/GaAs heterojunction bipolar transistors. We show that collector transit time is intimately related to base transport dynamics and high p-type carrier concentration in a thin base improves device performance. However, even for a very thin collector depletion region, the small Γ-X intervalley energy separation in GaAs places severe constraints on efficient collector transport.