QUANTITATIVE-ANALYSIS OF OVERLAPPING XPS PEAKS BY SPECTRUM RECONSTRUCTION - DETERMINATION OF THE THICKNESS AND COMPOSITION OF THIN IRON-OXIDE FILMS

The composition and thickness of thin iron oxide films on polycrystall ine pure iron were evaluated from Fe 2p spectra as measured by x-ray p hotoelectron spectroscopy. To this end the experimental spectra were r econstructed from reference spectra of the constituents Fe-0, Fe2+ and Fe3+, The background contributions in the spectra owing to inelastic scattering of signal electrons were calculated from the depth distribu tions of these constituents and their reference spectra, In the recons truction procedure the film thickness and the concentrations of Fe2+ a nd Fe3+ in the oxide film were used as fit parameters. The values obta ined for the oxide film thickness were compared with thickness values determined from the intensity of the corresponding O 1s spectra and wi th thickness values resulting from ellipsometric analysis. The sensiti vity of the reconstruction procedure with regard to film thickness and film composition was tested. (C) 1998 John Wiley & Sons, Ltd.