Analysis of charge, momentum and energy transfer by an impinging sub-keV electron beam on a conductor via Monte Carlo simulation including secondary-electron generation

Abstract

In this work, a Monte Carlo simulation code for the electron-beam propagation was developed using the Mott’s elastic scattering cross section and the Penn’s dielectric function to account for beam scatterings and energy losses. Additional steps were introduced to compute the electron density profile, the momentum distribution, and the kinetic energy deposited inside the target material due to the penetration of the beam. Details of the simulation were outlined and backscattering results were validated against available data in the literature. Various parameters that govern the simulation were discussed extensively. It was shown that the electron deposition distributions were highly non-uniform. The electron density inside the target was modified significantly due to the beam and it depleted at a few nanometers below the surface while charge accumulation occurred deeper below the surface. On the other hand, the electron momentum deposited within the workpiece showed sign of increasing average electron velocity in all directions. In terms of the kinetic energy transfer, the energy distribution reached maximum at a few nanometers below the surface. Results between gold (a conductor) and silicon (an insulator) were compared as well, and they differed in magnitude and local deposition distributions, although the overall trends of the deposition distributions were similar.