A hybrid model is developed to simulate electron transport through the emitter‐base heterojunction and the base region of abrupt heterojunction bipolar transistors. The energy distribution of the injected electron flux through the emitter‐base junction is calculated using a rigorous quantum‐mechanical treatment of electron tunneling and thermionic emission across the spike at the emitter‐base junction. The results are compared with those predicted by the conventional thermionic‐field‐emission model. For both models, the electron fluxes injected across the emitter‐base junction are used as initial energy distributions in a regional Monte Carlo calculation to model electron transport through the base. The average base transit times are calculated using the impulse response technique as a function of the emitter‐base voltage. The differences between the thermionic‐field‐emission model and the rigorous quantum‐mechanical approaches to model electron transport through abrupt heterojunction bipolar transistors are pointed out. ©1995 American Institute of Physics.