We report the first electronic-property results on atomic-layer deposited Al2O3/thermal-nitrided SiO2 stacking dielectric on n-type 4H SiC. The effects of the ultrathin thermal-nitrided SiO2 (2, 4, and 6 nm) on the SiC-based metal oxide semiconductor (MOS) characteristics have also been investigated, compared, and explained. A significant improvement in dielectric reliability and dielectric breakdown field has been observed after an ultrathin nitrided oxide has been introduced between Al2O3 and SiC. The best reported results were obtained from Al2O3 stacked with the thickest nitrided oxide (6nm). (c) 2006 The Electrochemical Society.