Monte Carlo study of secondary electron emission

Abstract

Based on our previous Monte Carlo simulation model of electron interactions with solids, including cascade secondary electron production, in which an optical dielectric function was used to describe electron energy loss and the associated secondary electron excitation, we have systematically investigated secondary electron generation and emission for 19 metals. The calculated secondary yield curve for primary beam energy ranging from 100 eV to 2 keV was found to correspond with the experimental universal curve. The dependence of the secondary yield on the work function was studied numerically, leading to a remarkable scattered deviation from Baroody’s relationship. This deviation shows that the secondary yield relates to different aspects of behavior by electrons in a metal, such as the cascade production process, the stopping power and specific energy loss mechanism for a sample, and the dependence on the electron density of states. The results provide an explanation for the scattered data on the experimental yield versus the work function. The calculations indicate that the characteristic energy loss of primaries may result in a corresponding feature in the energy distribution of secondaries.

Calculations of secondary electron yield of graphene coated copper for vacuum electronic applications

“…The latter implies that the number of such collisions can fluctuate, and so some electrons can occasionally suffer very large energy losses in close collisions with the atomic electrons. Though improved Monte Carlo formulations exist, 43,44 our primary goal is to qualitatively probe the physical mechanism behind SEY suppression by graphene monolayers. Refinements of our Monte Carlo including can easily be implement subsequently.…”

“…For example, inelastic scattering could be treated based on the dielectric function modelling theory by Penn, 45 and the imaginary part of the requisite dielectric function obtained from Density Functional Theory rather than using approximations. 43,44 Here, a more simplistic treatment is provided merely to obtain the qualitative trend of the SEY response in ultrathin graphene coated copper. Figure 1 shows our Monte Carlo simulation results, obtained for the secondary electron yield from pure copper without any graphene, as a function of the incident energy.…”

Monte Carlo Simulation of SEM and SAM Images

“…The SE yield and energy spectra are fairly important to the SEM image simulation for it implicates the interaction mechanism of electrons with a solid. In our previous studies reasonable values of secondary yield and satisfactory energy distribution curves as well as backscattering energy spectra (Ding et al, 2001;Ding et al, 2004b) have been successfully obtained, which has proved the reasonability of this MC model. For Si considered here, by using the full-Penn algorithm instead of single-pole approximation for the energy loss and considering more accurate SE excitation process, a good agreement had been obtained for absolute SE yield (Joy, 1995) and the SE spectrum (Joy et al, 2004) with experimental ones (Fig.…”

“…(6) is used to describe the energy loss of moving electrons, as well as the cascade secondary electron generation. The SPA was used in our previous simulation of SEs (Ding et al, 2001). After sampling the energy loss, E Δ , for an inelastic scattering event, a SE is assumed to be excited from the Fermi sea by adding the loss energy E Δ of the moving electron to the initial kinetic energy of the SE, with the excitation probability being proportional to a joint density of states of free electrons, i.e.…”

“…MC simulation is a powerful technique for simulation of secondary electron emission phenomena and calculation of the related energy spectra and yields of secondary electrons (Shimizu & Ding, 1992;Ding & Shimizu, 1996;Ding et al, 2001;Ding et al, 2004a). As described above, the generation of SEs is a cascade process due to multiple inelastic scattering.…”