Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 34: Focused Session: Epitaxial Graphene IV
O 34.3: Vortrag
Mittwoch, 25. März 2009, 11:30–11:45, SCH 251
Compressive strain relaxation through wrinkle formation in epitaxial graphene on Ir(111) — •Alpha T. N’Diaye1, Raoul van Gastel2, Johann Coraux1, Rabia Djemour1, Dirk Wall3, Niemma Buckanie3, Frank-J. Meyer zu Heringdorf3, Bene Poelsema2, Thomas Michely1, and Carsten Bussse1 — 1II. Phys. Inst., Universität zu Köln — 2MESA+ Institute for Nanotechnology, University of Twente, The Netherlands — 3Institut für Exp. Physik, Universität Duisburg–Essen, Germany
The growth of epitaxial graphene is often accompanied by the growth of prodruded elongated structures (e.g. on Pt(111)[1], 6H-SiC [2], Ir(111) ) which are sometimes interpreted as nanotubes or srcolls.
With scanning tunneling microscopy and low energy electron microscopy we have observed the growth of such structures during the growth of epitaxial graphene by chemical vapour deposition of ethene on Ir(111) . We suggest an alternative mechanism for the formation of such structures: Graphene is grown at elevated temperatures (≈ 1200 K). During cooldown compressive strain is induced due to the different thermal expansion coefficients of graphene and the iridium substrate. This strain can be partly relaxed through the formation of wrinkles in the graphene sheet. The remaining compressive strain at 300 K (≈ 0.4%) corresponds to a lock-in temperature between 700 K and 800 K. The length of wrinkles per surface area can be used to deduce the amount of compressive strain which they compensate for.
[1] D.E. Starr et al. Surface Science, 600 (2006) 2688-2695
[2] V. Derycke et al. Nano Letters, Vol. 2, No. 10 (2002) 1043-1046