Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 97: Graphene: Structure (jointly with O, HL)

TT 97.3: Talk

Thursday, March 19, 2015, 11:00–11:15, MA 041

Atomically Resolved Graphitic Surfaces in Air by Atomic Force Microscopy — •Daniel S. Wastl, Alfred J. Weymouth, and Franz J. Giessibl — University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany

Imaging at the atomic scale with atomic force microscopy in biocompatible environments is an ongoing challenge. We demonstrate here atomic resolution of graphite and hydrogen-intercalated graphene on SiC in air1. The main challenges arise from the overall surface cleanliness and the water layers which form on almost all surfaces2. To further investigate the influence of the water layers, we compare data taken with a hydrophilic bulk-silicon tip to a hydrophobic sapphire tip. While atomic resolution can be achieved with both tip materials at moderate interaction forces, the strong differences in force versus distance spectra can be related to the water layers on the tips and samples. Imaging at very low tip-sample interaction forces results in the observation of large terraces of a naturally-occurring stripe structure on the hydrogen intercalated graphene[1]. This structure has been previously reported on graphitic surfaces that are not covered with disordered adsorbates in ambient conditions (i.e. on graphite and bilayer graphene on SiC[3], but not on monolayer graphene on SiC). Both these observations indicate that hydrogen-intercalated graphene is close to an ideal graphene sample in ambient environments.

[1] Wastl, Weymouth, Giessibl, ACS Nano 8, 5233 (2014).

[2] Wastl Weymouth, Giessibl, Phys. Rev. B 87, 245415 (2013).

[3] Wastl et al., ACS Nano 7, 10032 (2013).