Regensburg 2010 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 47: Topical Session Growth Kinetics III
MM 47.1: Topical Talk
Thursday, March 25, 2010, 10:15–10:45, H4
Selecting a single orientation for millimeter sized graphene sheets — •Raoul van Gastel1, Alpha T. N'Diaye2, Dirk Wall3, Johann Coraux4, Carsten Busse2, Niemma M. Buckanie3, Frank-J. Meyer zu Heringdorf3, Michael Horn von Hoegen3, Thomas Michely2, and Bene Poelsema1 — 1University of Twente, Enschede, The Netherlands — 2Universität zu Köln, Köln, Germany — 3Universität Duisburg-Essen, Duisburg, Germany — 4Institut Néel/CNRS, Grenoble, France
We have used Low Energy Electron Microscopy (LEEM) and Photo Emission Electron Microscopy (PEEM) to study and improve the quality of graphene films grown on Ir(111) using CVD. CVD at elevated temperature already yields graphene sheets that are uniform and of monatomic thickness. Besides domains that are aligned with respect to the substrate, other rotational variants grow. Cyclic growth/etching, exploiting the faster growth and etch rates of the rotational variants, yields films that are > 99 % composed of aligned domains. Precovering the substrate with a high density of graphene nuclei prior to CVD yields pure films of aligned domains extending over millimeters. Upon cooling, branched line defects develop in the graphene films which are grown at high temperature. We demonstrate that these defects are wrinkles in the graphene layer, i.e. stripes of partially delaminated graphene that may ultimately provide anchor points for lift-off techniques. With LEEM we observe the reversible appearance and disappearance of the wrinkles and also observe strain relaxation to take place simultaneously with the formation of a wrinkle.