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DS: Fachverband Dünne Schichten
DS 45: Poster IV: One-Dimensional Metals: Reality or Fiction
DS 45.16: Poster
Thursday, April 3, 2014, 16:00–19:00, P1
Optical and electronic properties of rare-earth silicide nanowires on vicinal Si(001) — •Sandhya Chandola1, Eugen Speiser1, Stephan Appelfeller2, Martin Franz2, Norbert Esser1, and Mario Dähne2 — 1Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Berlin — 2Institut für Festkörperphysik, TU Berlin
Dy and Tb silicide nanowire structures on vicinal Si(001) surfaces are studied using in-situ Reflectance Anisotropy Spectroscopy (RAS) and Scanning Tunneling Microscopy (STM). Two different types of structures, metallic nanowires or a wire-like reconstruction, are formed by molecular beam epitaxy depending on the coverage and the annealing temperature. RAS of clean surfaces shows the typical features due to dangling bonds at the steps and Si dimers on the terraces. The silicide growth has a significant effect on the optical anisotropy, e.g. a feature develops at 3.8 eV for both structure types. This peak disappears after the surface is contaminated, confirming that it is unambiguously related to surface state transitions. Furthermore, RAS can identify how well-ordered the metallic nanowires are by the relative magnitude of this peak. The feature of the dangling bonds at the steps is significantly more affected for the wire-like reconstruction than for the metallic nanowires, as supported by the STM data showing that the reconstruction decorates many steps, thereby saturating the dangling bonds. Thus, RAS can be used as an optical fingerprint to distinguish different silicide nanowire structures. This work was supported by the DFG through FOR 1700 projects E2 and E3.