Generalized Ic vs VBE Characteristics of Bipolar Transistors

Abstract

A generalized IC V.S VBE Characteristics is derived for bipolar transistor (npn or pnp), which includes all the levels of carrier injection at the emitter and the impurity profiles in the base region. This generalized expression can be reduced to the conventional forms of collector current density for both low and high level current injections with arbitrary doping profiles in the base region. The degradations of minority carrier diffusivity (or mobility) due to impurity concentration and high current level injection are also considered. Comparisons of the experimental data and the theoretical results are made. Discussions and applications of the theoretical results are also given.