The current gain of silicon bipolar transistor has been quantitatively modeled at 77K and 300K in consideration of the carrier recombination currents in the emitter-base space charge region and in base
the extra base bandgap narrowing effect by the injection of minority-car-riers at high injection level
the Early effect
the conductivity modulation effects in base and in emitter
the effective base widening effect and the emitter current crowding effect. The obtained results are in agreement with the experimental data. The current gain is mainly determined by the conductivity modulation effect and emitter current crowding effect at 77K at high injection level
but at 300K
it is mainly determined by the effective base widening effect.