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O: Fachverband Oberflächenphysik
O 31: Poster Session - Metal substrates: Structure, Epitaxy and Growth
O 31.6: Poster
Montag, 16. März 2020, 18:15–20:00, P1C
Surface structure and chemical composition of the Te covered Au75Ag25(111) surface — •Tobias Kirschbaum, Tilman Kißlinger, Lutz Hammer, and M. Alexander Schneider — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
When depositing chalcogenides on clean transition metal surfaces the adsorbates coordinate substrate atoms to form a surface alloy or other surface structures [1,2]. The situation is unclear if a binary alloy functions as substrat. There, the chalcogenide has a variety of possibilities to bind within the surface and might be able to induce stoichiometries in the subsurface that differ from the bulk.
Here we present an investigation of the clean and Te covered Au75Ag25(111) surface by means of room-temperature scanning tunneling microscopy (STM) and low-energy-electron diffraction (LEED).
The clean Au75Ag25(111) surface is that of a disordered substitutional alloy. Our LEED-IV analysis (R = 0.064) proves an enrichment in silver in the second layer to ≈ 50%, whereas the other layers stay nearly bulk-like within the errors. Upon deposition of 1/3 ML Te at 90 K and annealing to at least 473 K a (√3 × √3)R30∘-structure forms. STM shows a honeycomb-like arrangement. A LEED-analysis confirms that this is a pure AgTe overlayer at hcp positions on a nearly bulk-like Au75Ag25(111) crystal.
[1] Jiaqi et al., Surf. Sci., 669, 198, 2018
[2] Liu et al., J. Phys. Chem. Lett., 10, 1866, 2019