Energy spectra of backscattered electrons in Auger electron spectroscopy: comparison of Monte Carlo simulations with experiment

Abstract

The primary energy dependecne and atomic-number dependence of backscattered electrons in Auger electron spectroscopy in the EN(E) mode have been investigated both theoretically and experimentally. A Monte Carlo simulation method with inclusion of cascade-secondary-electron production has been used to calculate the full energy distribution of backscattered electrons from the elastic peak down to the true-secondary-electron peak. The simulation model is based on the use of a dielectric function for describing inelastic scattering and secondary excitation, and on the use of Mott cross sections for elastic scattering. A systematic comparison between the calculated and experimental spectra measured with a cylindrical mirror analyzer has been made for Au, Ag, and Cu and for primary energies ranging from 0.5 to 5keV. Reasonable agreement was obtained for the backscattering background at primary energies in the keV region. A significant contribution of cascade-secondary electrons to the measured spectra on the low-energy side (less than 200eV ) was found. Experiments performed on elements with a wide range of atomic numbers have shown a quantitative common curve of the backscattering continuum when plotted on a logarithmic intensity scale in the intermediate energy region between 200eV and the low-loss peaks.