I-V, C-V and deep level transient spectroscopy study of 24 MeV proton-irradiated bipolar junction transistor

Abstract

This paper describes the effect of 24 MeV proton irradiation on the electrical characteristics of a pnp bipolar junction transistor 2N 2905A. I-V, C-V and DLTS measurements are carried out to characterize the transistor before and after irradiation. The properties of deep level defects observed in the bulk of the transistor are investigated by analysing the DLTS data. Two minority carrier levels, EC − 0.27 eV and EC − 0.58 eV and one majority carrier level, EV +0.18 eV are observed in the base collector junction of the transistor. The irradiated transistor is subjected to isochronal annealing. The influence of isochronal annealing on I-V, C-V and DLTS characteristics are monitored. Most of the deep level defects seem to anneal out above 400°C. It appears that the deep level defects generated in the bulk of the transistor lead to transistor gain degradation. A comparison of proton- and electron-induced gain degradation is made to assess the vulnerability of pnp transistor as against npn transistors.