QUANTITATIVE XPS - INFLUENCE OF ELASTIC ELECTRON-SCATTERING IN QUANTIFICATION BY PEAK SHAPE-ANALYSIS

A new method for non-destructive quantitative analysis of surface nano structures was developed in recent years. It relies on analysis of the XPS peak shape and usually the effects of elastic electron scattering are neglected in practical applications of the method. In the present paper we study the influence of elastic electron scattering for inter pretation of the analysed experimental data. Spectra of the Au 4d peak [with inelastic mean free path (IMFP) = 16 Angstrom] from a thin laye r of An atoms situated at varying depths in a Ni solid were analysed, When elastic scattering is neglected, the accuracy of the quantificati on is similar to 10% for depths smaller than 1.5 IMFP but for a depth of 2.5 IMFP the determined quantitative amount of gold is 25% too low, The effect of elastic scattering on the peak intensity was <10% for m arker depths up to 1 IMFP but it grows to similar to 40% at 2.5 IMFP. After correction for elastic scattering effects, the accuracy of the a nalysis is improved and the root-mean-square scatter in the determined amount of Au around the mean value is reduced from 15.4% when elastic scattering effects are neglected to 11% when they are included in the analysis. For the present system, it is then concluded that the effec t of elastic scattering is quite small for marker depths smaller than similar to 1 IMFP but for larger depths the effect is substantial. (C) 1997 by John Wiley & Sons, Ltd.