Roughness of the SiC/SiO2 vicinal interface and atomic structure of the transition layers

Abstract

The SiC/SiO2 interface is generally considered to be the cause for the reduced electron mobility of SiC power devices. Previous studies have shown a correlation between the mobility and the transition layer width at the SiC/SiO2 interface. The authors investigated this interface with atomic resolution Z-contrast imaging and electron energy-loss spectroscopy, and discovered that this transition region was due to the roughness of the vicinal interface. The roughness of a vicinal interface consisted of atomic steps and facets deviating from the ideal off-axis cut plane. The authors conclude that this roughness is limiting the mobility in the channels of SiC MOSFETs.