The physics and modeling of heavily doped emitters

The physics of minority-carrier injection and internal quantum efficiency of heavily doped emitters is studied through a novel computer simulation. It is shown that in the shallow emitters of modern devices, the transport of carriers through the bulk of the emitter, and the surface recombination rate are the dominant mechanisms controlling the minority-carrier profile. Carrier recombination in the bulk of the emitter only produces a small perturbation of this profile. This observation permits us to develop a simple and accurate analytical model for the saturation current and internal quantum efficiency of shallow emitters.