High-energy electron induced gain degradation in bipolar junction transistors

This paper describes the effect of 8 MeV electron beam on the forward current gain of space borne commercial indigenous bipolar junction transistors 2N2219A (npn), 2N3019 (npn) and 2N2905A (pnp). The devices are exposed to 8 MeV electron in the biased condition. The collector characteristics and Gummel plots are obtained as a function of accumulated dose. An excess base current model as well as Messenger-Spratt equation have been used to account for the observed gain degradation. The results indicate that 8 MeV electrons of high dose rate induce gain degradation by increasing the base current as well as decrease in collector current. The current gain degradation appears to be predominantly due to displacement damage in the bulk of the transistor. Off-line measurements of the hFE of the irradiated transistors indicate that the displacement induced defect and recombination centers do not anneal even at 150 °C.