Gamma irradiation effects on collector current and Early voltage of SiGe heterojunction bipolar transistor

The effects of gamma irradiation on collector current and Early voltage of silicon-germanium (SiGe) heterojunction bipolar transistor are investigated. After 104 Gy(Si) total dose irradiation, increases of the collector current and Early voltage are observed. Besides, both the threshold voltages and the breakdown voltages of the emitter-base and the collector-base junctions decrease. All the changes are thought to be mainly due to the reduction of effective carrier concentrations in the emitter and collector regions caused by radiation-induced defects.