Influence of low temperature oxidation and nitrogen passivation on the MOS interface of C-face 4H-SiC

Wet and dry thermal oxidations on carbon (C)-face 4H-SiC samples were carried out at temperatures of 850 °C, 900 °C, 950 °C, and 1000 °C at different durations, followed by Ar anneals at the same temperature as the oxidations and NO anneals at 1175 °C for different durations. The Fowler–Nordheim tunneling exhibits between 2 and 4 MV cm−1, respectively, and then the breakdown occurs at around 6–8 MV cm−1. The wet oxidation at 950 °C provides the lowest interface trap density of 4–6 × 1011 cm−2 eV−1 at 0.24 eV below the conduction band. Experiments also demonstrate that the oxide breakdown field for an N-implanted sample is lower than that of the non-implanted samples. However, the oxide breakdown field for an Al-implanted sample is even lower than that of the N-implanted sample, only 1.5 MV cm−1, mainly due to damage caused by ion implantation.