Monte Carlo calculation of the backscattering coefficient of thin films of low on high atomic number materials and the reverse as a function of the incident electron energy and film thickness

Abstract

In this study a CASINO Monte Carlo model has been used to investigate the behavior of the backscattering coefficient (η) for C-layer deposited on Au-substrate as well as for Au-layer deposited on C-substrate as a function of top-layer thickness and primary electron energy (0.5–10 keV). As the top-layer thickness increases and primary electron energy decreases, η-values became more affected by the material of the top layer. It depends on the maximum primary electron range compared with the thickness of the deposited top layer. The backscattering coefficient of a thin C-layer deposited on Au-substrate sharply increases toward Au values as the primary electron energy increases following the C bulk values. However, in the case of a thin Au-layer deposited on C-substrate, the backscattering coefficient starts with a value of that of a pure Au and increases to reach its maximum value and then starts decreasing toward the values of the C-substrate. The minimum and the maximum on the results are shifted toward the high energies as the top-layer thickness increases. The energy distribution of the backscattered electrons emerged from a thin 5 nm C-layer deposited on Au-substrate as well as from a thin 5 nm Au-layer deposited on C-substrate has been investigated as a function of primary electron energy. The results show the dependence of the backscattered electron energy distribution as well as the η-values on the differential scattering cross section.