Structural studies of two- and three-dimensional dysprosium silicides using medium-energy ion scattering

Medium-energy ion scattering has been used to determine the atomic structure of two-dimensional and three-dimensional (3D) dysprosium silicide films on the Si(1 1 1) surface. A quantitative study of the ion yield from the dysprosium has enabled the positions of the atoms in the top three layers of the Si(1 1 1)1×1–Dy to be precisely determined. For the case of the Si(1 1 1)(√3×√3)R30°–Dy 3D silicide surface the experimental blocking curves are in agreement with simulations for the structural model determined by surface X-ray diffraction for the Si(1 1 1)(√3×√3)R30°–Er 3D silicide surface. A contraction of 2.0±0.6% in the c-axis lattice constant compared to bulk dysprosium disilicide is found.