Numerical study of nonequilibrium electron transport in A1GaAs/GaAs heterojunction bipolar transistors.

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