Escape probability of electrons from solids. Influence of elastic electronscattering

The neglect of elastic electron scattering effects in the formalism of Auge r electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) ma y have substantial influence on results of quantitative applications, in pa rticular for large emission angles. This may lead to considerable errors in concentration depth profiles derived from the angle-resolved AES and XPS t echniques 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 elasti c collisions. If the function CF is known, a very simple formalism is obtai ned. In the present work we have found that an analytical expression result ing from solution of the kinetic Boltzmann equation within the transport ap proximation can effectively be used to calculate the CF function for any so lid, electron energy, and experimental configuration. It has been found tha t the CF function may differ from unity (which corresponds to negligible el astic scattering) by up to more than one order of magnitude. The accuracy o f the analytical formalism has been determined by comparison to an extensiv e database of the CF values obtained from Monte Carlo simulations of electr on transport in solids. The analytical expression was found to give CF valu es that agree with the Monte Carlo results within a mean percentage deviati on less than or equal to 10%. (C) 1999 Elsevier Science B.V. All rights res erved.