Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 62: Graphene III
O 62.8: Vortrag
Donnerstag, 25. März 2010, 12:15–12:30, H31
In situ monitoring of graphene growth on Ru(0001) by STM: new growth mode leading to extremely well ordered graphene — •Sebastian Dänhardt1, Sebastian Günther1, Joost Wintterlin1, and Stefan Schmitt2 — 1Department Chemie, Universität München, Butenandtstr. 11, 81377 München, Germany — 2SPECS GmbH, Voltastr. 5, 13355 Berlin, Germany
We present the results of an in situ study of graphene growth using a novel high temperature STM (SPECS STM 150 Aarhus HT). Graphene was grown by chemical vapor deposition of ethylene on Ru(0001) at temperatures between 380 and 780 °C while STM images were recorded. Three different growth modes were observed. At relatively low temperatures fractal structures form consisting of triangular units. At temperatures between 500 and 680 °C and at ethylene pressures of ~ 1*10-8 mbar graphene grows in a "downhill" fashion as found before by LEEM [E. Loginova, N. C. Bartelt, P.J. Feibelman, K.F. McCarty, New Journal of Physics 11 (2009) 063046]. At temperatures above 750 °C a new growth mode was observed. This mode is connected with massive etching of ruthenium step edges, while coherent, defect free graphene islands of micrometer size grow. Because the graphene islands are restricted to single terraces of the Ru substrate, the step structure of the Ru completely rearranges, and step bunches of up to 10 monoatomic step heights are formed. In this way, by applying the correct growth conditions, flat, defect-free graphene films can be grown on single terraces. The findings may lead to a massive improvement of graphene preparation via the "metal route".