A computer program to illustrate macro topography on electron backscattering

Abstract

This paper describes a computer program which enables the trajectories of an electron to be followed inside a solid sample and its pathway if it is successful to exit the sample's surface, and to be considered a backscattered electron (BSE). The simulation aids to understand the backscattering process and the effect of the sample that has other than an ideal flat surface topography. Several types of surface for the sample are simulated: a flat surface which can be tilted, a rough surface represented by a sine wave, and a circular surface to represent filamentous structures. The target material is entered as its empirical formula so that its mean atomic number may be calculated. It is covered with a layer of conductive coating, and it may be structured with vertical of horizontal layers of a second-phase material. Where appropriate, thr:position of the electron beam impacting on the target may be moved in relation to the underlying structures. The passage of the electron through the substrate is displayed on the computer monitor in high-resolution graphics. Information about those electrons which return to the sample surface and are backscattered is stored for later analysis. The paths of these BSEs are replotted to show the volume of the sample from which the image-forming data are derived. Further graphic output provides histograms of the energy distribution and of the BSEs exit direction.