Electron inelastic mean free paths: Influence of the modelling energy-loss function

Abstract

Accurate quantitative surface analysis using electron spectroscopies is of paramount importance in nanoscale-based technology of today. In this context, an appropriate description of the electron inelastic mean free paths (IMFP) is mandatory. We have studied the influence of several model dielectric descriptions of the momentum-dependent energy-loss function (ELF), beyond the extensively used Penn's approach, on the calculation IMFP in the 200-2000 eV kinetic energy range. It is found that the theoretical description of the ELF based on the extended Mermin oscillators predicts systematically lower values for IMFP than those obtained by Penn's approach. The deviations are of 6-8% in the 1000-2000 eV energy range and increase up to 10-15% at 200-400 eV, depending upon the particular material and kinetic energy considered. A phenomenological expression is proposed to correct this effect. Copyright © 2007 John Wiley & Sons, Ltd.