On the correlation between the inelastic mean free paths of secondary electrons and the secondary-electron yield parameter in some metal films

Abstract

The correlation between the inelastic mean free path of secondary electrons emitted during bombardment by electrons and the secondary-electron yield parameters for some metals is investigated. More specifically, the inelastic mean free paths of 50 eV electrons have been calculated for different metals using the TPP-2M method outlined by Tanuma et al. (Surf. Interface Anal. 21 (1994) 165). The choice of 50 eV was motivated by the fact that secondary-electron total yield measurements are normally made assuming that secondaries have a maximum kinetic energy of this magnitude. It is observed that the inelastic mean free paths correlate fairly well with the maximum value of the secondary electron yield (δ_m) with a linear dependence being obtained. This result indicates that the secondary yield is determined to a large extent by the scattering of the secondaries with the electron population near the Fermi level. The inelastic mean free paths of electrons with energies corresponding to the peak yield, δ_m, were also calculated by the TPP-2M method and found to show a linear dependence on the maximum secondary electron yield as well. Some aspects of the physical basis behind the correlations are addressed.