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O: Fachverband Oberflächenphysik

O 54: Poster Wednesday: 2D Materials 2

O 54.9: Poster

Mittwoch, 7. September 2022, 18:00–20:00, P4

The tellurization of Cu(111): From incorporated Te atoms via 1D-like surface reconstructions to closed films — •Andreas Raabgrund, Tilman Kisslinger, Maximilian Ammon, Lutz Hammer, and M. Alexander Schneider — Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany

We investigated the tellurization of Cu(111) from low Te coverages up to thick films both structurally and electronically by STM, STS, LEED-IV structural analysis, and DFT. For Θ<0.14 ML Te forms a substitutional surface alloy with short-range ordered patches of a (√7×√7)R19.1^∘ structure. Increasing the Te coverage leads to coexisting islands of a (3×√3)_rect superstructure which is well-ordered and fully developed at Θ=0.33 ML [1]. In the range 0.33 ML<Θ<0.40 ML, the (3×√3)_rect structure coexists next to a well-ordered (5×√3)_rect phase which is completely developed at Θ=0.40 ML [2]. Our LEED-IV analyses reveal arrangements of Cu2Te2 chains, whereby for the (5×√3)_rect phase a substantial reorganization of the surface into troughs allows to incorporate more Te. STS finds an unoccupied chain state, that has lower energy on the (3×√3)_rect which we interpret as an indication of delocalization with decreasing interchain distance. By further tellurization beyond Θ=1.1 ML closed Cu2-xTe films develop. For Θ>4 ML, a phase transition takes place below 300 K that results in a wrinkled appearance at low temperatures. On the surface two different reconstructions with distinct electronic fingerprint occur side-by-side. [1] T. Kißlinger et al., Phys. Rev. B 102, 155422 (2020)
[2] T. Kißlinger et al., Phys. Rev. B 104, 155426 (2021)