Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 101: Graphene: Preparation and characterization II (O, jointly with HL, TT)

HL 101.7: Talk

Friday, March 15, 2013, 12:00–12:15, H17

Precise imaging of graphene — •Thomas Hofmann, Alfred J. Weymouth, Joachim Welker, and Franz J. Giessibl — Institut für Experimentelle und Angewandte Physik, Universität Regensburg

Atomic imaging of graphene with a scanning probe microscope is challenging due to its small atomic lattice. We show that metallic tips, which have been characterized prior to the measurement, cannot truthfully image the graphene surface due to their large, non-spherical electron density [1]. Calculations predict that the metal tip atom strongly interacts with the graphene surface [2]. Carbon oxide front atom identification (COFI) [2] shows that contact of a clean metal tip with graphene can lead to graphene flakes attaching to the tip apex. This results in blurred images and multi-valley force versus distance curves. As a solution we use a metal tip, functionalized with an inert carbon monoxide molecule as suggested by Gross et al. [3]. The closed-shell nature of the CO drastically reduces the attraction between tip and graphene. Additionally, the small size of the CO allows truthful imaging of the graphene surface.

[1] *J. Welker, and F. J. Giessibl, Science 336, 6080 (2012)

[2]*M. Ondráček, P. Pou, V. Rozsíval, C. González, P. Jelínek, and R. Pérez, PRL 106, 176101 (2011)

[3]*L. Gross, F. Mohn, N. Moll, P. Liljeroth, and G. Meyer, Science 325, 5944 (2009)