Thin epitaxial metastable iron silicide overlayers with probably the CaF2-structure were grown on Si(111) by either solid-phase epitaxy or a layer-by-layer growth technique. After annealing in the 500–550C temperature range, a strong Si segregation at the surface was observed in ion scattering spectroscopy experiments. In low-energy electron diffraction these layers were characterized by a sharp p(2 x 2) pattern, which was shown to be due to a reconstruction of the Si-rich surface. Angle-resolved ultraviolet photoelectron spectroscopy revealed a characteristic surface electronic state with the same 2 x 2 periodicity in reciprocal space as the surface reconstruction. At the ¯Γ point, the surface state was located at 1.85eV binding energy in a relative gap of the calculated bulk electronic structure of fluorite-type FeSi2.

Si-Rich p(2 x 2) Surface Reconstruction of Epitaxial Fluorite-Type Iron Silicide Layers on Si(111). U.Kafader, P.Wetzel, C.Pirri, G.Gewinner: Applied Surface Science, 1993, 70-71[2], 573-7