Defects and electrical behavior in 1 MeV Si+-ion-irradiated 4H-SiC Schottky diodes

In this paper, the formation and evolution of defects induced by ion irradiation with 1 MeV Si+ ions in Ni2Si/4H-SiC Schottky diodes were studied and correlated with the electrical properties of the contacts. The current-voltage characteristics of the contacts monitored before and after irradiation showed an increase of the Schottky barrier height, of the series resistance, and of the leakage current with increasing irradiation fluence. The changes in the barrier height and in the series resistance values could be attributed to the dopant deactivation in the near-interface region, while the increase of the leakage current was associated with the formation of irradiation-induced defects. These defects showed an evolution with increasing irradiation fluence. Moreover, a combination of deep-level transient spectroscopy and current-voltage measurements of the diodes allowed us to demonstrate that the Z(1)/Z(2) center of 4H-SiC has the major influence on the increase of the diodes leakage current in the irradiated material.