Monte Carlo simulation of electron interaction with a thin film

Abstract

A Monte Carlo simulation (MC) of medium energy electron transport in solids is usually checked, where possible, by comparing calculated values with experimental ones. Unfortunately, some quantities are very difficult to measure, even though it is important to know them for proper analytical measurement by electron probe microanalysis. One of the most important parameters is the dimensions of the volume at which the interaction of electrons with matter produces X-ray radiation. In our previous works, reasonably good agreement was found between calculations and experiments for the electron backscattering coefficient, and also for X-ray emission, especially k-ratios (the ratio of intensities from sample and standard). By our MC code, we calculated these quantities for Au thin films on a Si substrate in dependence on the electron energy (in the range 5–30 keV, i.e. in the range used in SEM) and film thickness (in the range 0.05–0.5 μm). In this paper, we try to define the dimensions of the interaction volume for a thin film on a substrate of other material. According to this definition, and for the samples defined above, we present the values of the maximum efficient depth of X-ray production and those of the diameter of the interaction volume, calculated by our code. In addition to the produced intensities of characteristic X-ray radiation, we calculate both the radial and the depth profiles of X-ray production in the sample.