Electron irradiation effects in AlGaAs/GaAs single heterojunction bipolar transistors

The effects of high-energy electron irradiation on the dc characteristics of polyimide passivated AlGaAs/GaAs HBTs of different base thicknesses and different emitter sizes are investigated. The devices show gain degradation for doses greater than 10/sup 15/ e/cm/sup 2/. The gain degradation of the passivated devices decreases (1) with increase in the base thickness, (2) with increase in the perimeter to area ratio of the emitter, and (3) with increase in the base current. Our results suggest that the observed gain degradation due to electron irradiation is mainly caused by an increase in the emitter-base junction space charge region recombination.