Impacts of band alignment change after interface nitridation on the leakage current of SiO2/4H-SiC (0001) and (11̄00) MOS capacitors

The band alignments and leakage currents were investigated after post-oxidation annealing in NO ambient (NO-POA) for SiO2/4H-SiC (0001) and () metal-oxide-semiconductor capacitors. Significant increase in conduction band offset was observed after NO-POA on SiO2/4H-SiC (0001) interface whereas decrease on SiO2/4H-SiC () interface, which would be related to different dipoles direction on (0001) and () faces, respectively. We found that leakage currents originated by both Fowler–Nordheim tunneling and Poole–Frenkel emission were significantly higher on () than on (0001) after NO-POA at elevated temperatures, indicating that band alignment should be considered as important factor to employ various crystal faces for power devices.