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

The d.c. characteristics of InGaAs/InP single heterojunction bipolar transistors (SHBTs) were studied for the first time under high energy (~l MeV) electron radiation of cumulative dose up to 5.4 * 10^15 electrons/cm^2. No degradation was observed for electron doses below 10^15/cm^2. For electron doses greater than 10^15/crn^2 the following degradation effects were observed: (1) decrease in collector current: (2) decrease in current gain up to 50%; (3) an increase in collector saturation voltage by 0.2-0.8 V depending on base current; and (4) increase in output conductance. 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. The increase in collector saturation voltage is attributed to an increase in emitter contact resistance after irradiation. The increase in the avalanche multiplication in the reverse biased base-collector junction caused by radiation induced defects is believed to be responsible for increased output conductance after irradiation, (c) 1999 Elsevier Science Ltd. All rights reserved.