Leakage Current Suppression by Passivation of Defects by Anodic Oxidation of 4H-SiC Schottky Contacts

To suppress the negative influence of defects on 4H-SiC Schottky barrier diode characteristics, we have developed a new method called passivation of defects by anodic oxidation (PDA). This method utilizes anodic oxidation as a means to form oxide films on defects of the 4H-SiC surface, and these oxide films can function as a resistive layer to the leakage current of Schottky barriers. We observed the current--voltage characteristics of Ni Schottky contacts on 4H-SiC before and after PDA. We found that the leakage current was significantly suppressed after PDA, while the increase in series resistance caused by PDA can be negligible when we apply PDA for an optimum time duration. These results suggest that the PDA method is a promising technique to improve the performance of 4H-SiC Schottky barrier diodes.