Berlin 2024 – scientific programme

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O: Fachverband Oberflächenphysik

O 30: Poster: Proximity Effects in Epitaxial Graphene

O 30.1: Poster

Tuesday, March 19, 2024, 12:30–14:30, Poster A

Quasi-freestanding graphene on SiC(0001) by intercalation of silicon — •Niclas Tilgner and Thomas Seyller — TU Chemnitz Institut für Physik

To observe the extraordinary properties of freestanding graphene, the atmospheric pressure growth of epitaxial graphene has proven itself in recent years. Thereby the annealing of SiC samples in [0001] direction gives rise to a graphitisation of the surface and a carbonrich (6√3 × 6√3)R30^∘ reconstruction is formed. This so-called buffer layer is topological equivalent to graphene, but the π-bands are strongly deformed due to remaining bonds to the substrate. One way of decoupling is the intercalation of foreign atoms, which gives rise to a quasi-freestanding graphene layer. In the presented work the decoupling could be achieved by intercalation of silicon. The poster focuses on the discussion of three different preparation techniques in terms of their influence on the sample quality. The investigated methods are the silicon deposition at elevated temperatures, the sequential deposition/annealing and an exchange intercalation. For the latter one, the buffer layer was first decoupled with hydrogen before the process with silicon. Experiments using the diffraction of low energy electrons (LEED) reveal that only with one technique a sufficiently ordering of the silicon could be achieved. Further investigations with photoemission (ARPES, XPS) show the appearance of several surface states on the ordered samples, which are partly attributed to one of the Hubbard bands of the silicon dangling bonds.

Keywords: graphene; intercalation; silicon; Mott-Hubbard states; photoemission