Monte Carlo modeling of surface excitation in reflection electron energy loss spectroscopy spectrum for rough surfaces

Abstract

It has been experimentally found that the surface roughness influences strongly the surface and bulk plasmon excitation by glancing-angle reflection electron energy loss spectroscopy (REELS). However, there is still little theoretical work dealing with the surface roughness effect in REELS. Such a work is required to predict REELS spectra accurately, providing an understanding of the experimental phenomena observed. In this study, we use a finite element triangle mesh method build in a fully 3D rough surface model based on the surface topography measured by atomic force microscopy. Then REELS spectra for these rough surfaces are theoretically simulated by using Monte Carlo simulation including surface plasmon excitation and bulk plasmon excitation. The simulation results for Al sample with different surface roughnesses agree well with experimental data. Based on the analysis of the maximum depth of backscattered electrons and the depth distribution of surface bulk excitation under different conditions of roughness, the influence of surface roughness to the surface excitation in REELS spectra can be well understood.