Monte Carlo Electron Trajectory Simulation
Lenox Job, Stanley J. Ng,D. T. Le and Guangming Zhang
Department of Mechanical Engineering & Institute for Systems
Research
University of Maryland, College Park, MD 20742
Basic Principle
The length of the basic repetitive step in such a calculation is usually
set equal to the mean free path for elastic scattering ("single scattering
Monte Carlo") or a multiple thereof ("multiple scattering Monte Carlo").
From the meanfree path and the rate of energy loss due to inelastic scattering
as calculated with the Bethe or Joy-Kuo expressions, the decreasing energy
can be calculated along the path of the electron. After the electron travels
a distance equal to the mean free path, the next scattering site is reached,
and a new scattering angle is chosen for the next step based upon the new
value of the energy. The scattering angle is calculated only from expressions
based upon elastic scattering since inelastic scattering causes negligible
angular deviation. Since the elastic scattering angle can take on any value
over a wide range from 0 to 180 degrees, random numbers are used with an
appropriate weighting factor to produce the appropriate statistical distribution
of scattering. Because of the extensive use of random numbers in the simulation,
the name "Monte Carlo" is applied to this technique.
From: Scanning Electron Microscopy and X-ray Analysis, Goldstein et al.
Figure 1 Scheme of Monte Carlo Simulation