Dresden 2011 – scientific programme
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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.42: Poster
Wednesday, March 16, 2011, 17:30–21:00, P4
Growth of Graphene on Ir(100) — •Pascal Ferstl, Matthias Gubo, Lutz Hammer, and M. Alexander Schneider — Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstr. 7, 91058 Erlangen
Graphene monolayers have been grown on a variety of different metal substrates with hexagonal symmetry. In contrast, the growth on substrates with square symmetry remains rather unexplored so far. Therefore, we have studied graphene growth on a Ir(100) surface by means of LEED and STM. Both, temperature programmed growth (TPG) and chemical vapour deposition (CVD) at various temperatures were tested with C2H4 as reacting gas. For TPG we find as a function of the reaction temperature a sequence of different superstructures indicative of the stepwise hydrocarbon decomposition towards surface carbide. Randomly oriented graphene islands are formed for temperatures above 700∘C. By CVD at 700 - 900∘C graphene forms domains oriented along the [001] direction, with an angular tolerance below ±4∘. There are no indications for a Moiré structure from the LEED pattern. In contrast, ethylene deposition at higher temperatures (900 - 1300∘C) leads to a preferential alignment of the graphene layer 5∘ off [001]. Also, a complex Moiré pattern is observed in LEED. In STM we find two graphene phases for all deposition temperatures: one being essentially flat, while the other shows a linear corrugation with an amplitude of up to 3 Å and a lateral spacing of about 22 Å. Possible structural models will be discussed.