Analytical modeling of base transit time considering recombination in the non-uniformly doped base

The main objective of this paper is to show that recombination in the base needs to be taken into account in determining base transit time τ_B. In previous analytical works for τ_B, recombination in the base was neglected. In this paper both drift and diffusion currents for electron and hole are considered in obtaining minority carrier profile n(x). In the model, both SRH and Auger recombination are considered. The energy-bandgap-narrowing effects due to heavy doping, velocity saturation as well as doping and field dependent mobility are considered. The model shows that recombination has significant effects on the base transit time of a heavily doped base.