Effects of Different Collector Current Biases on γ Radiation Response of npn-BJT

The total dose effect of γ irradiation at different biased collector currents on Si npn-BJTs was investigated.The experimental results show that the irradiation-induced degradation of an npn-BJT increases with the total dose;however,it decreases with the increase of the collector current at the same total dose.This phenomenon cannot be well explained by the recent space charge model.In this paper,a revised model is presented,in which there are electrically neutral dipoles near the Si-SiO2 interface of the extrinsic base region.By using the new model,all the experimental results have been well interpreted.