Degradation of InGaAs-InP heterojunction bipolar transistors under high energy electron irradiation

The DC characteristics of InGaAs-InP single heterojunction bipolar transistors (SHBTs) were studied for the first time under high energy (/spl sim/1 MeV) electron radiation with a cumulative dose up to 5.4/spl times/10/sup 15/ electrons/cm/sup 2/. The following degradation effects were observed for electron doses greater than 10/sup 15//cm/sup 2/: (1) decrease in collector current, (2) decrease in current gain by up to 50%, and (3) an increase in collector saturation voltage by 0.2-0.8 V depending on base current. The increase in collector saturation voltage is attributed to an increase in emitter contact resistance after irradiation. The degradation of collector current and current gain are thought to be due to increased recombination caused by radiation-induced defects in the base-emitter junction.