Escape probability of electrons from solids. Influence of elastic electron scattering

The neglect of elastic electron scattering effects in the formalism of Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) may have substantial influence on results of quantitative applications, in particular for large emission angles. This may lead to considerable errors in concentration depth profiles derived from the angle-resolved AES and XPS techniques where these effects are usually not taken into account. Recently, we proposed to describe the effects of elastic electron scattering on AES and XPS peak intensities by a function CF defined as the ratio of the depth distribution functions derived from models that include and neglect elastic collisions. If the function CF is known, a very simple formalism is obtained. In the present work we have found that an analytical expression resulting from solution of the kinetic Boltzmann equation within the transport approximation can effectively be used to calculate the CF function for any solid, electron energy, and experimental configuration. It has been found that the CF function may differ from unity (which corresponds to negligible elastic scattering) by up to more than one order of magnitude. The accuracy of the analytical formalism has been determined by comparison to an extensive database of the CF values obtained from Monte Carlo simulations of electron transport in solids. The analytical expression was found to give CF values that agree with the Monte Carlo results within a mean percentage deviation less than or equal to 10%. (C) 1999 Elsevier Science B.V. All rights reserved.