Correlation between surface morphology and breakdown characteristics of thermally grown SiO2 dielectrics in 4H-SiC MOS devices

We have investigated the surface and interface morphology of a thermally grown SiO
₂
/4H-SiC(0001) structure by atomic force microscopy and transmission electron microscopy. It was found that the surface roughness results in thickness fluctuation of thermal SiO
₂
due to the pronounced oxidation near the steps. Thus, the localized high elevated electric field near the steps accelerates dielectric degradation and hence results in poor gate oxide reliability.