Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 4: Graphene I
O 4.7: Vortrag
Montag, 26. März 2012, 12:00–12:15, MA 041
Morphology-dependent corrugation of Graphene/Ir(111): An XSW study — •Sven Runte1, Chi Võ Vǎn2, Johann Coraux2, Jörg Zegenhagen3, Thomas Michely1, and Carsten Busse1 — 1II. Phys. Inst., Universität zu Köln, Germany — 2Institut Néel, Grenoble, France — 3European Synchrotron Radiation Facility, Grenoble, France
Graphene grown on metal substrates often shows a superperiodic moiré structure due to the lattice mismatch. In the resulting large unit cells varying local registries between the carbon and the metal atoms are found, leading to a local variation of the respective bond strength. Hence the graphene layer is not flat but significantly corrugated [1].
We performed X-ray Standing Wave (XSW) measurements for graphene/Ir(111) using (111)- and (222)-crystal reflections to determine the height distribution of the carbon atoms. We show that the peak-to-peak corrugation for a fully closed film is 1 Å and about half this value for small graphene flakes. This can be rationalized by postulating different strain states resulting from the cool-down from high growth temperatures and different thermal expansion coefficients of graphene and its substrate. These measurements also clarify the open question of the real shape of the corrugated layer from scanning probe experiments [2,3]. Finally, the influence of intercalated atoms and metal clusters on graphene’s corrugation is shown.
[1] C. Busse et al., Phys. Rev. Lett. 107, 036101 (2011).
[2] A. T. N’Diaye et al., New J. Phys. 10, 043033 (2008).
[3] Z. Sun et al., Phys. Rev. B 83, 081415 (2011).