Interface properties of metal-oxide-semiconductor structures on 4H-SiC{0001} and (112(-)over-bar) formed by N2O oxidation

4H-SiC(0001), (0001), and (1 1 0) have been directly oxidized by N2O at 1300 degrees C, and metal-oxide-semi conductor (MOS) interfaces have been characterized. The inter-face state density has been significantly reduced by N2O oxidation on any face, compared to conventional wet O-2 oxidation at 1150 degrees C. Planar n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated on 4H-SiC(0001), (0001) and (1 1 0) faces have shown effective channel mobilities of 26, 43, and 78 cm(2)/Vs, respectively. Secondary ion mass spectrometry analyses have revealed a clear pileup of nitrogen atoms near the MOS interface. The thickness of the interfacial transition layer can be decreased by N2O oxidation. The crystal face dependence of the interface structure is discussed. A simple consideration of chemistry indicates that NO2 generated from the decomposition of N2O, may be a more efficient oxidant of carbon than O-2.