Computer simulation of radiation induced emitter crowding

Radiation induced emitter crowding effects can precipitate an anomalous photocurrent response. Such a response would not be predicted by the usual computer simulation using a charge control representation of a bipolar transistor equipped with a primary photo-current source. Radiation induced emitter crowding effects are prevalent in large epitaxial power transistors which operate with low impedance loads where large photocurrent s are observed as a result of irradiation. A model has been developed which simulates radiation induced emitter crowding and it is applicable to most existing circuit analysis codes. Experimental data obtained from pulsing 50 watt silicon epitaxial power transistors with 50 nanosecond and 8 microsecond linear accelerator pulses in the electron beam mode show excellent agreement with the predicted results.