Monte Carlo Simulation Study of Electron Interaction with Solids and Surfaces

A brief overview is given on several aspects of applications of the Monte Carlo (MC) simulation method to surface-related electron spectroscopy and microscopy. For the MC modeling of electron interaction with solids, the electron inelastic scattering cross section is calculated by the use of bulk dielectric function with optical constants in a dielectric functional approach. This has enabled the systematic reproductions of the experimental energy distributions of backscattered electrons for a number of elemental materials. An improved calculation of backscattering factor for quantitative AES analysis has been performed on the basis of a new definition and by making use of the up-to-date relevant cross sections. The physical reason is given for the backscattering factor that can be less than unity for very low primary energies close to the ionization energy and/or for large incident angles. For the MC modeling of electron interaction with surfaces, the inelastic scattering of electrons moving in a surface region is treated in a self-energy formalism. The model has enabled the evaluation of the surface excitation effect through the calculation of position-dependent electron IMFP. A simulation of REELS spectra for Ag is compared with an experiment; a reasonable agreement found on the surface plasmon peak intensity normalized with elastic peak intensity thus verifies this modeling of electron interaction with surfaces. Finally, the MC simulation code has been extended to deal with complex sample geometries. By using basic building blocks to construct a complex geometry and the ray-tracing technique for correction of electron flight-step-length sampling, the structured and/or inhomogeneous sample can be modeled with reasonable flexibility. Copyright (C) 2006 John Wiley & Sons, Ltd.