Elastic backscattering of electrons: determination of physical parameters of electron transport processes by elastic peak electron spectroscopy

Abstract

This review paper is concerned with elastic peak electron spectroscopy (EPES) and information it gives on electronic transport phenomena. Experimental methods are described for determining the physical parameters such as the inelastic mean free path (IMFP), the life time of hot electrons, the elastic- and inelastic-scattering cross sections, the surface excitation parameter (SEP), etc. used by Auger electron spectroscopy, X-ray photoelectron spectroscopy, reflection electron energy loss spectroscopy, electron microscopy, etc. These quantities are associated with the elastic reflection coefficient r e of the solid, appearing in the elastic peak I e( E p). r e is a material parameter, determined by E energy, Z atomic number and by the angular conditions. It is measured by EPES. I e( E p) is affected by the electron spectrometer parameters, such as energy resolution, angular conditions and the full width at half maximum of the electron source. The phenomenological properties of the elastic peak and the physical processes are presented, including subtle effects such as extended fine structure, recoil and refraction of electrons. Experimental problems are discussed including sample cleaning, surface layer amorphization, crystallinity effects, spectrometers, their calibration, reference standard samples, etc. Calculation methods for the relevant parameters and the evaluation of experiments (by Monte Carlo simulation) are briefly described. Applications of EPES for determination of the physical parameters (IMFP, the elastic- and inelastic-scattering cross sections, SEP) are briefly reviewed. Besides a compilation of the literature, some new results are presented.