AVS 51st International Symposium
    Applied Surface Science Tuesday Sessions
       Session AS-TuM

Paper AS-TuM7
Monte Carlo Simulations of Electron Backscattering from Surfaces in Scanning Auger Microscopy

Tuesday, November 16, 2004, 10:20 am, Room 210A

Session: Electron Spectroscopies
Presenter: C. Powell, NIST
Authors: C. Powell, NIST
A. Jablonski, Institute of Physical Chemistry, Poland
Correspondent: Click to Email
Monte Carlo (MC) simulations are useful for calculating signal intensities in AES because multiple-scattering events can be conveniently included. In this contribution, a new MC algorithm for AES is presented in which recent advances in knowledge of electron transport are incorporated. Differential cross sections for elastic scattering were obtained from a NIST database.@footnote 1@ The inelastic-scattering events were described by energy-loss functions derived from optical data, and "recommended" inelastic mean free paths for energies up to 10 keV were utilized.@footnote 2@ The empirical formula of Casnati et al.@footnote 3@ was used to describe inner-shell ionization cross sections. Particular care was taken in preparing the random number generators for simulation of the angular and energy distributions after elastic- and inelastic-scattering events because of numerous sharp features (e.g., deep minima) in the relevant probability distributions. We report new calculations of the backscattering factor (BF) for Auger transitions of Si, Cu, Ag, and Au as a function of primary energy, and find that the BF depends also on the Auger-electron emission angle. We investigated the radial distribution of emitted Auger electrons from a thin Cu film on Si and Au substrates. Due to the effects of electron backscattering, the radius of the analysis area depends considerably on the primary energy and the substrate, and can be much larger than the radius of the primary beam. We also examined the effects of backscattering on Auger line scans in the vicinity of the edge of a Cu film on Si and Au substrates. @FootnoteText@ @footnote 1@A. Jablonski, F. Salvat, and C. J. Powell, NIST Electron Elastic-Scattering Cross-Section Database, Version 3.1, SRD Database 64 (2003). @footnote 2@C. J. Powell and A. Jablonski, J. Phys. Chem. Ref. Data 28 (1999) 19. @footnote 3@E. Casnati, A. Tartari and C. Baraldi, J. Phys. B 15 (1982) 155.