When a triangular shape for the electric field in the base-collector space-charge region of an n-p-n Si BJT (bipolar junction transistor) is assumed, the electron mean energy can be calculated analytically from a simplified energy-balance equation. On this basis a nonlocal-impact-ionization model, suitable for computer-aided circuit simulation, has been obtained and used to calculate the output characteristics at constant emitter-base voltage (grounded base) of advanced devices. Provided the experimental bias-dependent value of the base parasitic resistance is accounted for in the device model, the base-collector voltage at which impact-ionization-induced snap-back occurs can be accurately predicted.
Prediction of impact-ionization-induced snap-back in advanced Si n-p-n BJTs by means of a non-local analytical model for the avalanche multiplication factor / Verzellesi, Giovanni; Baccarani, G.; Canali, Claudio; Pavan, Paolo; Vendrame, L.; Zanoni, E.. - In: IEEE TRANSACTIONS ON ELECTRON DEVICES. - ISSN 0018-9383. - STAMPA. - 40:(1993), pp. 2296-2300.