Characterization of ex-situ hydrogenated amorphous SiC thin films by X-ray photoelectron spectroscopy

The X-ray photoelectron spectroscopy (XPS) characterization of an ex-situ hydrogenated amorphous SiC film shows the following main features for the as-received specimen: (1) carbidic Si2p and C1s states with binding energies (BE) 100.4 ± 0.1 and 282.9 ± 0.1 eV respectively, (2) oxidic Si2p and O1s states with BE 103.2 ± 0.1 and 531.9 ± 0.1 eV respectively, (3) a strong C1s state at BE 286.8 ± 0.1 eV, (4) an O1s state with BE 533.0 ± 0.1 eV, and (5) a small adventitious carbon signal. These results, combined with the corresponding data on the as-grown film before hydrogenation and with the changes accompanying controlled Ar+ sputtering, lead to the following model for the film surface: About two monolayers of adventitious carbon cover a 15 Å thick, oxygen-containing carbon layer which in turn overlays a 25 Å thick SiO2 layer in contact with the bulk SiC. A good part of the oxidic layer and the oxygen in the carbon layer appear to have been inadvertently produced during the hydrogenation process.