Layer-resolved depth profiling at single crystal surfaces

The stopping power and straggling of ions in channeling and blocking direct ions depend on multiple scattering and impact parameter dependent effects. Therefore. the extraction of high-resolution depth profiles of single cryst als based on simulation of the energy spectra obtained from medium-energy i on scattering (MEIS) is not straightforward. An alternative is to analyze t he MEIS angular (blocking) scattering yields from several angular configura tions. We have applied this technique to obtain laver resolved depth profil es in a dilute substitutional alloy, Fe-9 wt% W (1 0 0). and in an alloy wi th a small mass difference between the base metals. Fe-15 wt% Cr (100). As a result, layer-resolved depth profiling combined with conventional MEIS st ructural analysis allowed a detailed study of surface segregation phenomena in these systems. (C) 2001 Elsevier Science B.V. All rights reserved.