Measurements and simulation of avalanche breakdown in advanced Si bipolar transistors

A complete analytical model for impact ionization effects in bipolar transistors, which is able to predict the behaviour of advanced devices up to breakdown, is presented. A simple expression of the carrier mean energy suitable for circuit simulation is used to calculate the device multiplication coefficient and enables the influence of non-equilibrium transport on impact ionization to be accounted for. The role played by the reverse base current in determining the snap-back of the common base output characteristics is investigated both experimentally and theoretically.