Monte Carlo simulations of backscattered electron coefficients and average penetration depths for Cu, Au, and Al under electron irradiation

Abstract Understanding and analyzing backscattered electron coefficients (BSCs) and average penetration depths (APDs) are critical in material science and electron microscopy. However, despite their importance, there are relatively few studies that cover a wide range of energies and a variety of materials for accurately calculating BSCs and APDs. Therefore, a Monte Carlo (MC) simulation was conducted to examine and explore the electron backscattering coefficients and average penetration depths of copper (Cu), gold (Au), and aluminum (Al) when bombarded by energetic electrons with energies ranging from 0 to 60 kilo-electron volts (keV) at normal incidence. The results showed strong agreement with experimental data. First, for the BSCs, we have deviations ranging from 0.3 to 5.4%. Second, the empirical calibration adjustment resulted in an excellent agreement with the experimental data of APDs. For Cu, the deviation was 3.32% at 5 keV. The exceptional agreement was observed at 9 keV for Au, with a deviation of just 0.08%. In the case of Al, the adjustment achieved a strong agreement with a deviation of 2.01%. These findings improve our understanding of backscattered electrons behavior by providing accurate simulations for Cu, Au, and Al across a wide energy range, resolving discrepancies, especially for low-Z materials such as aluminum (Z = 13). The improved accuracy in predicting APD and the original BSC results support scanning electron microscopy (SEM) applications, particularly in compositional and topographic imaging.