Vibrational signature of oxygen on 6H-SiC(0 0 0 1)

This paper reports on the analysis of vibrational modes of atmospheric adsorbates on the 6H-SiC(0 0 0 1) surface by means of high resolution electron energy loss spectroscopy (HREELS). Three vibrational O-Si-O modes on silicon carbide were registered for the first time with high accuracy. Furthermore, a strong dependence of the energy of the antisymmetrical Si-O-Si stretching vibration on oxygen coverage and isochronal annealing temperature was observed. By means of HREELS and in comparison to photoelectron spectroscopy, we show that the bonding of oxygen to the top silicon atoms prevents the penetration of contaminants into the material.