A nitride layer was formed on a SiC surface by direct nitridation in pure N2 or in NH3 diluted with N2. The SiO2 layer was deposited by the thermal decomposition of tetraethylorthosilicate (TEOS) on the nitride layer to form an MIS diode. The XPS analysis showed that the nitride layer was oxidized during the deposition process of SiO2. The direct nitridation was effective to reduce the interface state density between the insulating layer and 4H-SiC

Abstract. The SiO2 layer was deposited on the 4H-SiC Si face by the thermal decomposition of tetraethylorthosilicate(TEOS) in N2 atmosphere to from MIS diodes. The post deposition annealing was effective to improve the interface properties. The interface state density of the deposited SiO2/SiC MIS structure was estimated to be the order of 10 11 cm -2 eV -1 by Terman method. The direct nitridation of SiC surface prior to the deposition of the SiO2 layer was effective to reduce the interface state density.