Anomalous Scatter of Forward Current-Voltage Characteristics of He+-Irradiated Ni/4H-SiC Schottky Diodes

A study of forward current-voltage characteristics of Ni/4H-SiC Schottky diodes (SDs) before and after irradiation with He+ ions revealed features that characterize defect structures and reveal the degradation mechanism of the diodes. These features are the presence of excess currents of certain type in the unirradiated SDs, their appearance in forward-biased originally ideal SDs, and a >10 orders of magnitude scatter of the series resistance of the SDs upon their irradiation with He+ ions. A model of localized defect-induced current paths (shunts) in the form of unintentionally produced SDs with the substrate is suggested.