Characterization of Nitride Layer on 6H-SiC Prepared by High-Temperature Nitridation in NH3

The nitride layers were prepared by direct thermal nitridation of 6H-SiC substrates at 1200–1570°C in a NH3 atmosphere. The layer was characterized by using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Raman scattering spectroscopy. The thickness of the nitride layers prepared at lower than 1400°C was estimated to be less than 10 nm. The higher nitridation temperature resulted in the formation of a thicker surface layer. XPS measurement showed that the surface layer was composed of N, Si, C and O. Peaks corresponding to α-Si3N4 were detected in the Raman spectra and the XRD patterns of the sample prepared at higher than 1500°C, indicating the crystallization of the nitrided layer.