Comparisons of calculated and measured effective attenuation lengths for silicon dioxide over a wide electron energy range

Abstract

We report calculations of effective attenuation lengths (EALs) for Si 2p photoelectrons in silicon dioxide at photoelectron energies between 82 and 1385 eV. These EALs are compared with measured values reported recently by Shimada et al. (Surf. Interf. Anal. 29 (2000) 336) at photoelectron emission angles of 0° and 55° for photoelectron energies between 140 and 1000 eV. Close agreement is found between the calculated and measured energy dependencies of the EALs for photoelectron energies between 400 and 1000 eV. Agreement is also found in the absolute values if the SiO 2 film thicknesses in the experiments were increased by 29% or if the inelastic mean free paths used in our calculations were decreased by the same percentage. Deviations between measured and calculated EALs for energies between 140 and 400 eV are attributed to the effects of surface-plasmon excitation. Calculated EALs for a photoelectron emission angle of 55° were larger than those found for normal photoelectron emission, particularly for low photoelectron energies, as was found in the Shimada et al. experiments.