Transport and noise in GaAs/AlGaAs heterojunction bipolar transistors. I. Transport and high current gain

A simple physical description of conduction and current grain in GaAs/AlGaAs double heterojunction n-p-n transistors is given using the barrier height, transport, and recombination processes that have been determined from the bias and temperature dependence of their forward characteristics. Gain saturation, high base resistance, and a gain creep process are explained in terms of band bending at the heterojunctions and its lowering by injection and collector bias. This description provides the foundation for interpretation of low-frequency noise and gain phenomena