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

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 5 keV. 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 200 eV ) 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 200 eV and the low-loss peaks. (C) 2004 American Institute of Physics.