Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 32: Epitaxie und Wachstum II
O 32.12: Vortrag
Donnerstag, 27. März 2003, 17:45–18:00, FOE/ANOR
Growth of Cobalt monolayers on Si(111) studied by STM — •Matthias Löffler1,2, Martin Weinelt1, Enrique Ortega2, and Thomas Fauster1 — 1Lehrstuhl für Festkörperphysik, Staudtstraße 7, D-91058 Erlangen, Germany — 2Donostia International Physics Center, Apto. 1072, 20080 San Sebastian, Spain
Various experiments have studied the initial growth of cobalt silicides on Si(111), and the submonolayer √7 × √7 R 19.1 ∘-reconstruction is well analyzed. Only few studies have reported a √13 × √13 R 13.9 ∘-reconstruction [1]. We investigated this surface structure with scanning tunneling microscopy (STM) and Low Energy Electron Diffraction (LEED) for a coverage of one monolayer (ML).
The √13×√13 R 13.9 ∘-reconstruction depends strongly on the surface morphology. The growth is influenced by the deposition mode (reactive or solid phase epitaxy) and the deposition rate. We investigated the transition from the flat, mainly √13×√13 R 13.9∘-reconstructed surface, to the high temperature CoSi2 phase, which is dominated by three-dimensional island growth. In this case a 2 × 2-reconstruction with sharp LEED spots and simultaneously a √7 × √7 R 19.1 ∘-reconstruction with broad LEED spots are observed. With STM the 2 × 2-reconstruction can only be found on top of islands while the √7 × √7 R 19.1 ∘-reconstruction is formed on flat regions between islands. For temperatures above 530 ∘C the 2 × 2-phase changes to the 1 × 1-phase and the √7 × √7 R 19.1 ∘-reconstruction remains between islands.
[1] A. E. Dolbak, Surf. Sci. 373 (1997), 43