High Resolution Photoemission Study of the 6H-SiC/SiO2 Interface

Core and valence band photoemission measurements with a spatial resolution of 150 microns were used to probe the SiO2/6H-SiC(0001) interface. To this end a thermally grown 100 nm thick oxide was etched back in the form of a wedge with a slope of 65 A/mm down to the SiC substrate. From an analysis of the energies and intensities of Si2p and Cls core levels as a function of position on the sample a 22 A thick interface layer has been identified which consists of silicon suboxide (SiO(1.5)) interspersed in a carbon matrix. The ratio of C:Si is 3:1 in this interface layer. The valence band offset between 6H-SiC and SiO2 was determined to be 2.9(1) eV. (Author)