SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Poster Session II: Metal substrates II
O 18.1: Poster
Montag, 1. März 2021, 13:30–15:30, P
Atom exchange and registry shift upon formation of surface tellurides on Ag(111) and Cu(111) — •Andreas Raabgrund, Maximilian Ammon, Tilman Kisslinger, Lutz Hammer, and M. Alexander Schneider — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
The formation of (surface) metal alloys using Te achieved a lot attention lately, e.g. for photovoltaics or thermoelectrics [1]. In this work, we study the initial stages of Te surface alloy formation on Ag(111) and Cu(111) by STM, STS, LEED, and DFT. For coverages below 0.14 ML tellurium is readily incorporated into the topmost substrate layer via local atomic exchange. The process occurs already at or below room temperature and eventually leads to a (√7×√7)R19.1∘ short-range order. Increasing the Te coverage leads to coexisting islands of a (√3×√3)R30∘ superstructure on Ag(111) [2] and a (2√3×√3)R30∘ superstructure on Cu(111) [3], which are well-ordered and fully developed at Θ=1/3 ML Te. In these two phases, the top layer has 1:1 stoichiometry in hcp registry to the substrate and only 2/3 of the surface sites are occupied. The Te atoms are only threefold coordinated in-plane. STS data shows that the substitutional Te phases have a distinctly different electronic structure from that of the well-ordered phases at Θ=1/3 ML. Notably, the unoccupied dispersing states with spz character are not found anymore in the range EF to EF + 2.5 eV. [1] Ibers J., Nat. Chem. 1, 508 (2009) [2] Ünzelmann et al, Phys. Rev. Lett. 124, 176401 (2020) [3] Kisslinger T., Phys. Rev. B. 102, 155422 (2020)