Physical mechanisms of the influence of γ-ray surface treatment on the characteristics of close AuNi/n–n+-GaN Schottky contacts

Abstract

The results obtained here suggest that low-dose 60Co γ-irradiation (Dγ ∼ 140 Gy) has a complex effect on close AuNi/n–n+-GaN{0001} Schottky contacts. This manifests in the disappearance of current steps in the initial section of the forward current–voltage curve, improvement in the average values of the ideality factor n, a decrease in the average values of the true Schottky barrier height ϕ bn in the middle section and an increase in series resistance R S and enhancement of the inhomogeneous metal–semiconductor contact series resistance effect in the final section. In all cases, the observed changes are sustainable. A combination of the Zur–McGill–Smith close Schottky contact defect model, the inhomogeneous contact model and the radiation-induced defect formation model provides an explanation for the physical mechanisms of changes observed in electrophysical and instrumental characteristics after γ-irradiation. Such mechanisms are associated with changes in the electrophysical nature of GaN structural defects (dislocations and interface states) and degradation of the homogeneity of contact conductivity. This paper shows that the low-temperature anomaly also manifests itself in close AuNi/n–n+-GaN Schottky contacts subjected to γ-irradiation.