Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 33: Graphene

O 33.9: Poster

Tuesday, March 17, 2015, 18:15–21:00, Poster A

Thickness, roughness and electronic structure characterisation of graphene using soft x-ray reflection spectroscopy — •Christine Jansing¹, Hud Wahab², Marc F. Tesch^1,3, Markus Gilbert¹, Andreas Gaupp¹, Andrey Sokolov³, Dong Hee Shin⁴, Suk-Ho Choi⁴, Hans-Christoph Mertins¹, Heiko Timmers², Dominik Legut⁵, and Peter M. Oppeneer⁶ — ¹Münster Uni. of Applied Sciences, D-48565 Steinfurt — ²School of Physical, Environmental and Mathematical Sciences, Uni. of New South Wales Canberra, Canberra, Australia — ³HZB, D-12489 Berlin — ⁴Dep. of Appl. Physics, College of Appl. Science, Kyung Hee Uni., Yongin 446-701, Korea — ⁵Nanotechnology Centre, Ostrava, Czech Republic — ⁶Depart. of Physics, Uppsala Uni., Uppsala, Sweden

X-ray reflection spectroscopy has been performed on graphene layers supported by different substrates across the C 1s absorption edge. Results confirm that the chemical vapour deposition onto copper foil has produced graphene of monolayer coverage. Graphene, deposited under the same conditions, transferred with a PMMA carrier to other substrate materials, has been measured to be significantly thicker. The interface- and the surface-roughness of the graphene layers have been determined. Structure in the measured reflection spectra can be correlated with ab-initio electronic band structure calculations and assigned to C 1s electron excitations. For the graphene layers transferred to a SiO2 substrate a feature is present that indicates excitation at an energy that is 1.8 eV less than the energy associated with the π* orbital. This finding is consistent with NEXAFS observations.