Evaluation of charging effects during X-ray photoelectron spectroscopy measurements of ultra-thin SiO2/Si interfaces

The binding energy of the Si⁴⁺ component of the Si 2p core-level peak and the single O 1s core-level peak observed for the SiO ₂/Si system exhibit energy shifts towards higher energies as the oxide thickness is increased. The Si⁰, Si¹⁺, and Si³⁺ 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 Si⁴⁺ and O 1s. The identical energy shift for Si⁴⁺ and O 1s is a clear indication of X-ray induced charging effect of SiO₂ as compared to the small charging effect induced in the substrate. The similar shift for Si¹⁺ and Si ³⁺ components and the Si⁰ component arising from the bulk Si has been explained by the interface structure