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

Abstract

A Monte Carlo simulation including surface excitation, Auger electron-and secondary electron production has been performed to calculate the energy spectrum of electrons emitted from silicon in Auger electron spectroscopy (AES), covering the full energy range from the elastic peak down to the true-secondary-electron peak. The work aims to provide a more comprehensive understanding of the experimental AES spectrum by integrating the up-to-date knowledge of electron scattering and electronic excitation near the solid surface region. The Monte Carlo simulation model of beam-sample interaction includes the atomic ionization and relaxation for Auger electron production with Casnati's ionization cross section, surface plasmon excitation and bulk plasmon excitation as well as other bulk electronic excitation for inelastic scattering of electrons (including primary electrons, Auger electrons and secondary electrons) through a dielectric functional approach, cascade secondary electron production in electron inelastic scattering events, and electron elastic scattering with use of Mott's cross section. The simulated energy spectrum for Si sample describes very well the experimental AES EN(E) spectrum measured with a cylindrical mirror analyzer for primary energies ranging from 500 eV to 3000 eV. Surface excitation is found to affect strongly the loss peak shape and the intensities of the elastic peak and Auger peak, and weakly the low energy backscattering background, but it has less effect to high energy backscattering background and the Auger electron peak shape.

Ionizing Doses Calculations for Low Energy Electrons in Silicon and Aluminum

“…5 shows the MC results for an energy spectrum of Auger electrons in silicon. Our MC simulations are in fairly good agreement with the MC simulations and the experimental results of Cao et al [36] for the L 2,3 VV and the L1L 2,3 V transitions. Fig.5.…”

“…Energy loss spectrum for backscattered electrons in silicon (after [25]). Our experimental spectrum corresponds to E0=1990 eV with an accuracy of 0.1 eV whereas our MC spectrum (dashed line with an accuracy of 0.5 eV) and the experimental measurements of Cao et al [36] are for E0=1000 eV. The RMSD calculations are given for the energy loss axis.…”

“…The surface plasmon excitation (sp) corresponds to the shoulder at 11.6 eV. It is less noticeable than the volume plasmon excitations on both simulated and experimental spectra [36]- [37]. The discrepancies between spectra (height and width of the peaks) may mainly result from the experimental set-up (angle between the electron beam and the sample, angle between the sample and the analyzer) or the surface state (oxidation).…”

“…Energy spectrum for the L2,3VV and L1L2,3V Auger transitions in silicon at E0=1000 eV (after [25]). Full lines are the MC simulation and the experimental measurements of [36]. The dashed line is our MC simulation given with an accuracy of 1 eV.…”

Quantum-trajectory Monte Carlo method for study of electron–crystal interaction in STEM

“…(11) is used instead to sample the energy loss and hence the energy of generated SE. 6 It should be noted that the experimental optical data used in the dielectric functional approach includes also the contribution from inner-shell ionizations; we have to remove the inner-shell edges from experimental optical energy loss function 48 to avoid double counting of the ionizations. Since the energy loss E  is comparatively small with respect to electron energy E , the electron having suffered an inelastic scattering and at an energy of E E   is treated here to move along the same quantum trajectory as at E in order to avoid the computational complexity.…”