Model Parameters and Degradation Mechanism Analysis of Indium Phosphide Hetero-Junction Bipolar Transistors Exposed to Proton Irradiation

Abstract

The degradation properties of Indium phosphide hetero-junction bipolar transistors (InP HBTs) under proton irradiation are studied and modelled using a compact model for pre-irradiation, post-irradiation, and post-annealing. The variation rates of the model parameters, such as the base–emitter saturation current (ISE) and ideality factor in the ideal region (NE) in the forward Gummel characteristics, the zero-biased capacitance (Cje) and the grading factor (Mjer) in the BE junction capacitance, and the transit time parameter in the base region (Tfb), are analysed to delve into the degradation mechanism induced by proton irradiation. The displacement damage, induced by proton irradiation in the space charge region of the base–emitter junction and in the quasi-neutral bulk base region, is found to be responsible for the decrease in current gain and cut-off frequency. After annealing, the variation rates of the parameters decrease significantly compared to post-irradiation. This suggests that the recombination of unstable defects leads to a slight recovery in the degradation characteristics of InP HBTs after a period of annealing.