This work presents improved channel mobility of n-channel metal-oxide-semiconductor field-effect transistors(MOSFETs) on 4H-SiC, achieved by gate-oxide nitridation in nitric oxide. Lateral enhancement mode MOSFETs were fabricated using standard polycrystallinesilicon gate process and 900?àannealing for the source and drain contacts. The low field mobility of these MOSFETs was as high as 48 cm2/Vs together with a threshold voltage of 0.6 V, while the interface state density-determined from the subthreshold slope-was about 3ױ011?eV-1?cm-2. The 43-nm-thick gate oxide of coprocessed metal-oxide-semiconductor structures exhibited a breakdown field strength of 9 MV/cm.