Determination of the mean free path of electrons in solids from the elastic peak

Abstract

The simple theoretical model described in Part I [1] is applied to evaluate experimental results determined by elastic peak electron spectroscopy and published previously. The inelastic mean free path λ determined from the elastic backscattering probabilityP _e of 2.2 and 3.1 keV electrons on C, Si, Ge and Mo are in reasonable agreement with results of Seah and Penn. In the evaluation σ_eff elastic backscattering cross sections calculated with the Thomas—Fermi—Dirac potential model have been applied. This model, however, is not suitable for W and Au high atomic number elements. A detailed discussion is given on the problems associated with the measurement ofP _e taking into consideration the CMA response, deconvolution and angular distribution of electron spectra. Another method for determining λ is given by comparing the elastic peaks of two elements and their σ_eff backscattering cross sections. Experimental results are presented for Al, Si, Ge, GaAs, GaP, InSb, GaSb, Sb, InP, SiO₂ and Si₃N₄, atomic clean surfaces measured with a CMA atE _P=1, 1.5, 2 and 3 keV at normal incidence. Good agreement was found with literature data collected by Ashley for Al−Si, Ge−GaAs. The IMPF λ of GaP and GaSb proved to be 10% larger than those of GaAs, results not available in the literature. New results as well are published for λ of Sb, InSb and InP. The good agreement with literature data justifies the application of the simplified model described in Part I.