Study on ionization damage of silicon-germanium heterojunction bipolar transistors at various dose rates

Ionizing radiation effects in silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) at different dose rates were investigated. Experimental results show that the base current increases with increasing accumulated dose for the high and low dose rates of irradiation, causing a significant drop in current gain. Besides, the lower the dose rate, the higher the radiation damage, which demonstrates a significantly enhanced low-date-rate sensitivity (ELDRS) effect in the SiGe HBTs. The different degradation behaviors for high and low dose rates of irradiation are compared with each other and discussed; furthermore, the underlying physical mechanisms are analyzed and investigated in detail.