Self-consistent particle simulation for (AlGa)As/GaAs HBTs with improved base-collector structures

A one-dimensional self-consistent particle simulation was developed for (AlGa)As/GaAs heterojunction bipolar transistors (HBTs) to investigate how far device performance can be improved by positively utilizing nonequilibrium electron transport phenomena. Hole plasmon scattering and the screening effect on LO phonon scattering were proved to play an essential role in determining the minority-carrier temperature in a heavily doped base layer. The computation was carried out for HBTs with various types of base and collector structures. The electron transport mechanisms are discussed in detail in connection with the reduction in base-to-collector transit time. Intrinsic device performance is expected to improve with the cutoff frequency exceeding 150 GHz, as a result of adopting a graded-gap base and a p-type collector structure, even under a heavily doped base condition.>