A Monte Carlo method using Mott cross-sections for elastic scattering and a modification of the Bethe continuous-slowing-down by inelastic scattering at inner- shell electrons has been used to calculate linescans across surface edges and steps using a two-detector system for SE and BSE with exit momenta to the right (detector A) and to the left (detector B). The step height h=10R, R, R/2, R/5 and R/10 (R = electron range) and the inclination angles 𝛂=30°- 80° of edges and steps have been varied to get information about the influence of these quantities on the linescans. The signals contain contributions by surface tilt contrast, electron diffusion contrast, self-shadowing of the specimen and 'mutual illumination' caused by backscattered electrons re-entering the specimen. The latter results in a larger increase of the signal for an extended step relative to a surface edge with the same angle 𝛂
The difference signals A-B contain information about the surface profile. The SE A-B signal is in first order proportional to tan 𝚽 and the BSE A-B signal is proportional to sin 𝚽 where 𝚽 denotes the local surface tilt angle. Reconstructions of the surface profile using the calculated signals show the errors caused by signal contributions different to pure surface tilt contrast.
Reimer, L. and Stelter, D.
"Monte Carlo Calculations of Electron Emission at Surface Edges,"
Scanning Microscopy: Vol. 1
, Article 9.
Available at: https://digitalcommons.usu.edu/microscopy/vol1/iss3/9