On the formation of concentration profiles by low-energy ion bombardment and sputter depth profiling

An analytical model is developed to describe the generation of concentratio n profiles in binary solids under low-energy ion bombardment. The model acc ounts, in particular, for preferential sputtering and radiation-enhanced pa rticle transport in the solid, and is found to apply for a quantitative rep resentation of steady-state concentration microprofiles in the near surface region of initially homogeneous binary targets as Fe-silicides. A model-ba sed evaluation of such profiles delivers absolute values of the correspondi ng coefficients for radiation-enhanced diffusion. The numerical solution en ables to trace the profile evolution in dependence of the bombarding time o r ion fluence. When being applied to sputter depth profiling of a pre-exist ing concentration profile, a severe influence of the actual sputter yield r atio of the target components is found which may completely deteriorate the characteristics of the profile to be analyzed. (C) 2000 Elsevier Science B .V. All rights reserved.