Evaluation of charging effects during X-ray photoelectron spectroscopy measurements of ultra-thin SiO/sub 2//Si interfaces

The binding energy of the Si/sup 4+/ component of the Si 2p core-level peak and the single O 1s core-level peak observed for the SiO/sub 2//Si system exhibit energy shifts towards higher energies as the oxide thickness is increased. The Si/sup 0/, Si/sup 1+/, and Si/sup 3+/ components of the Si 2p core-level peak also exhibit a shift to higher energies but the values are much small as compared to that of Si/sup 4+/ and O 1s. The identical energy shift for Si/sup 4+/ and O 1s is a clear indication of X-ray induced charging effect of SiO/sub 2/ as compared to the small charging effect induced in the substrate. The similar shift for Si/sup 1+/ and Si/sup 3+/ components and the Si/sup 0/ component arising from the bulk Si has been explained by the interface structure.