Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 2: Scanning probe techniques: Method development I

O 2.8: Vortrag

Montag, 12. März 2018, 12:15–12:30, MA 004

COFI characterization and imaging of graphene with O-terminated Cu tips — •Alexander Liebig, Daniel Meuer, Angelo Peronio, and Franz J. Giessibl — Institute of Experimental and Applied Physics, University of Regensburg, Germany

The use of chemically inert tips allows to directly probe the repulsive interaction regime and thus to obtain high spatial resolution. Gross et al. found in 2009 [1] that CO terminated metal tips enable intramolecular resolution imaging of organic molecules. Later, it was found that terminating the tip apex with noble gas atoms [2] achieves a similar spatial resolution. Recently, Mönig et al. [3] proposed to use oxygen terminated Cu tips that apparently are also quite inert, but are stiffer in lateral directions than CO tips. To further characterize such O-terminated tips, we apply the COFI method [4], where a CO molecule adsorbed on the Cu surface is used to probe the tip apex. With COFI we are able to resolve the atomic structure of the tip apex. We then use a CuO tip that was characterized with COFI to measure on a graphene monolayer grown on SiC. AFM images of graphene recorded with CO-terminated tips show a deformation of the graphene honeycomb lattice due to the flexibility of the tip apex [5]. We find that for close distances we also see a deformation of the graphene lattice when measuring with an O-terminated Cu tip.

[1] L. Gross et al., Science, 325 (2009) 1110. [2] F. Mohn et al., Appl. Phys. Lett., 102 (2013) 073109. [3] H. Mönig et al., ACS Nano, 10 (2016) 1201. [4] J. Welker, F.J. Giessibl, Science, 336 (2012) 6080. [5] M.P. Boneschanscher et al., ACS Nano, 6 (2012) 10216.