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O: Fachverband Oberflächenphysik

O 45: Graphene: Adsorption, Intercalation and Doping

O 45.2: Poster

Dienstag, 8. März 2016, 18:15–20:30, Poster E

Interaction of 10 nm-sized Co, Pd, and Ti islands with epitaxial graphene — •Anastasia Sokolova, Franziska Kilchert, and M.Alexander Schneider — Solid State Physics, Friedrich-Alexander University Erlangen-Nürnberg, Germany

We investigated the adsorption and intercalation properties of metals (Co, Pd and Ti) relevant for contact formation on epitaxial graphene on 6H-SiC(0001) by Scanning Tunneling Microscopy (STM).

When evaporated at substrate temperatures below 100°C, all three metals form (111) and (0001) oriented ad-islands. Only titanium showed a tendency to decorate substrate step edges. Judging from the cobalt and palladium ad-island stability with respect to material pick up by the STM tip, palladium forms weaker bonds to graphene than cobalt. Titanium ad-islands could also be removed by the STM tip. However we observe in the majority of cases that the graphene underneath is removed. We take this as an indication of a strong chemical interaction between titanium and graphene.

After annealing to approximately 600°C Co and Pd readily intercalate while Ti does not. Co intercalates by forming metal islands below the graphene sheet similar in size as the previous ad-islands, while Pd additionally formed large (> 50 nm in lateral size) patches growing from step edges or holes in the graphene sheet indicating coalescence of intercalated material.