Abstract: Due to the restriction of gate dielectrics quality and interface characteristics of insulators on SiC substrates, potential of the wide-band-gap semiconductor material in high-power application field has still not been realized.Major progresses on this research project are summarized, at the same time, affects of C atoms on the quality and interface state density in thermal SiO₂/SiC system are discussed.A potential method for SiC MOS devices and circuits is proposed to improve the performance and reliability.