Structure ofFe3Si∕GaAs(001)epitaxial films from x-ray crystal truncation rods

Abstract

Thin ($10--15\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ thick) ${\mathrm{Fe}}_{3}\mathrm{Si}$ films are grown on GaAs(001) by molecular beam epitaxy and studied in situ by grazing incidence x-ray diffraction. We find two interfacial structures in different samples, with the first atomic layer of ${\mathrm{Fe}}_{3}\mathrm{Si}$ consisting of either iron atoms only or both Fe and Si atoms. In both cases, the top atomic layer at the surface contains both Fe and Si atoms. The films are fully ordered, except 1 or 2 monolayers at the surface, where Fe and Si atoms within one and the same atomic layer are intermixed.