Impact of nitridation on the reliability of 4H-SiC(112-bar 0) MOS devices

The leakage current and flat-band voltage (V_FB) instability of NO-nitrided SiC(112-bar 0) (a-face) MOS devices were systematically investigated. Although NO nitridation is effective in improving the interface properties, we found that it reduces the onset field of Fowler-Nordheim current by about 1 MV cm⁻¹, leading to pronounced leakage current. Synchrotron radiation X-ray photoelectron spectroscopy revealed that the nitridation reduces the conduction band offset at the SiO₂/SiC interface, corroborating the above finding. Furthermore, systematical positive and negative bias stress tests clearly indicated the enhancement of V_FB instability of nitrided a-face MOS devices against electron and hole injection. (author)