The ST component in the Si 2p photoemission spectrum from H-terminated and oxidized Si (001) surfaces

Abstract

One doublet is usually employed to fit the Si0 substrate species in the Si 2p photoemission spectra from Si (001) H-terminated (after piranha treatment) and oxidized surfaces. However, there is a second substrate-top component (ST) with a binding energy of 0.3 eV higher than the bulk component; its intensity varies from ∼10% at normal emission (i.e., 90° from the surface) to ∼20% at 35°. It is present even for oxidized surfaces and does not correspond to any of the suboxide species. It corresponds to the first layers of the substrate and is responsible for the decrease in the signal dip between the two S–O branches of the Si 2p spectra for glancing electron takeoff angles. Although it is resolvable for monochromatized sources, the ST component is absent in the literature on Si 2p spectra.