Oxidized silicon surfaces studied by high resolution Si 2p core-level photoelectron spectroscopy using synchrotron radiation

The Si 2p soft X-ray photoemission study of various oxidized surfaces (ther mal oxidation and room temperature (RT) oxidation) shows the benefit derive d from the use of high-energy resolution (70 meV). Interesting structural i nformation can be retrieved from an analysis of the line widths of the oxid es, suboxides, and elemental Si peaks. In particular the binding energy (BE ) of elemental silicon layers adjacent to the oxidized layer can be disting uished from that of deeper silicon layers (the two prominent 'interfacial' elemental Si lines are shifted by about +0.2 and -0.2 eV). These new data s how a possible effect of oxygen second neighbors on elemental Si 2p binding energies. Moreover, changes in the oxide/suboxide line widths - as seen in a comparative study of the Si(1 1 1)-7 x 7 surface thermally oxidized in O -2 and exposed at RT to O-2 or H2O - may be attributed to static disorder, i.e., variations in Si-O bond lengths. (C) 2001 Elsevier Science B.V. All r ights reserved.