COMPARISON OF IONIZING-RADIATION-INDUCED GAIN DEGRADATION IN LATERAL,SUBSTRATE, AND VERTICAL PNP BJTS

A comparison is presented of ionizing-radiation-induced gain degradati on in lateral, substrate, and vertical PNPs. The dose-rate dependence of current gain degradation in lateral PNP BJTs is even stronger than the dependence previously reported for NPN BJTs. Various mechanisms ar e presented and their relative significance for gain degradation in th e lateral, substrate, and vertical PNPs is discussed. A detailed compa rison of the lateral and substrate PNP devices is given. The specific lateral and substrate devices considered here are fabricated in the sa me process and possess identical emitters. Even though these devices h ave identical emitters and undergo the same processing steps, the late ral devices degrade significantly more than the substrate devices.