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O: Fachverband Oberflächenphysik

O 4: Graphene I

O 4.6: Talk

Monday, March 26, 2012, 11:45–12:00, MA 041

SPA-LEED study of strain state of single layer graphene on Ir(111): hysteretic behaviour of lattice parameter and wrinkle formation — •C. Klein¹, H. Hattab¹, A. T. N'Diaye², D. Wall¹, G. Jnawali¹, J. Coraux³, C. Busse², R. van Gastel⁴, B. Poelsema⁴, T. Michely², F.-J. Meyer zu Heringdorf¹, and M. Horn-von Hoegen¹ — ¹Department of Physics, Universität Duisburg-Essen — ²II. Physikalisches Institut, Universität zu Köln — ³Institut Néel, CNRS-UJF, Grenoble Cedex 9, France — ⁴Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands

Employing high resolution low energy electron diffraction (SPA-LEED) the lattice parameter of single layer graphene on Ir(111), prepared by thermal decomposition of ethylene at 1530 K, was studied. We analyzed the strain state and the wrinkle formation kinetics as function of temperature. Using the moiré spot separation as a magnifying mechanism for the difference in the lattice parameters between Ir and graphene, we achieved an unrivalled relative precision of ca. 0.1 pm for the graphene lattice parameter. Our data reveals a characteristic hysteresis of the graphene lattice parameter which is explained by the interplay of reversible wrinkle formation and film strain. We show that epitaxial graphene on Ir(111) always exhibits residual compressive strain at room temperature, and provide important guidelines for strategies to avoid wrinkling.

Hattab et. al., Nano Letters (under revision, Nov. 2011)