Abstract: Al gate MOS capacitor is fabricated using thermally oxidized 30nm SiO2 layer grown on n type 4H-SiC epitaxial layer by synthesizing H2 and O.2.The C-Vcharacteristics are measured and analysed.According to the results,the interface feature of SiO2-SiC and doping concentration of the n type 4H-SiC epitaxial layer are obtained.The interface has quite good quality and the interface state density is small.The doping concentration of uniform n type 4H-SiC epitaxial layer is 1.84e17cm-3.

Key words: 4H-SiC,  MOS capacitor, C-V characteristics,  thermally oxidized SiO2