Minority current in the base region of bipolar transistors under high-level injection conditions

A simple expression is derived for the electron current in the base region of n-p-n bipolar structures under high-level injection conditions. Comparison between the predicted results and those obtained from an exact computer simulation is presented. The expression for Jnis related to the Gummel equation [1] and is in a form particularly suited to use with partitioned device models. It is restricted, however, to cases where the impurity charge in the base is approximately constant, an approximation that will be examined.