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

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 f'act 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 (delta(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, delta(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. (C) 2000 Elsevier Science B.V. All rights reserved.