The Backscattering Correction Factor in AES: A New Outlook

Abstract

There is currently renewed interest in the backscattering correction for Auger electron spectroscopy (AES). There are several reasons for this interest. First, the energy of the primary-beam energy reaches 25 keV in modern AES instruments and Shimizu's predictive formulae based on calculations for primary energies between 3 keV and 10 keV are of uncertain validity at higher energies. Second, it has been shown recently that the present definition of the backscattering factor is based on a simplified model of electron transport that breaks down for low primary energies and/or more grazing-incidence angles. A new term, the backscattering correction factor (BCF) has therefore been introduced that is based on an advanced model of electron transport. Third, much progress has been recently made in the theory of electron transport and the data for electron-scattering parameters which should improve the reliability of calculated backscattering correction factors. Finally, the BCF from the advanced theoretical model has been found to depend on numerous parameters defining the solid, the selected Auger transition, and the experimental configuration. Since the derivation of a simple predictive formula for the BCF does not seem to be feasible, a computer-controlled database has been developed to provide BCFs for a user-specified material and experimental configuration. Examples are given of BCFs from the advanced and simplified models for Ag M 4 N 45 N 45 Auger electrons from silver.

Monte Carlo simulation of full energy spectrum of electrons emitted from silicon in Auger electron spectroscopy

“…For example, backscattering continuum has been used to calculate an important correction factor for quantitative analysis by AES, the backscattering factor, which represents the contribution of backscattered electrons in addition to that of incident electrons to the inner‐shell ionization for Auger electron generation in the surface region . Even though the new calculation of backscattering correction factor has not used directly the simulated backscattering continuum, the accuracy of calculation still relies on our knowledge about electron scattering and electronic excitation which can be tested via a comparison of Monte Carlo simulation of the full energy spectrum with precise experimental measurement.…”