Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 101: Graphene IV: Electronic Properties and Structure

HL 101.10: Vortrag

Freitag, 11. März 2016, 12:45–13:00, S051

Force-induced dynamic STM mapping and picking of freestanding graphene membranes — •Bernd Uder, Wolf-Rüdiger Hannes, and Uwe Hartmann — Fachrichtung Experimentalphysik, Universität des Saarlandes, Saarbrücken, Germany

Scanning Tunneling Microscopy (STM) of freely suspended membranes only a few atomic layers thick is inherently challenging. Membrane and tip instabilities are easily induced and must be controlled by careful adjustment of scan and regulation parameters. So far only little STM work has been reported on this surface type. We demonstrate seamless imaging of few-layered suspended graphene, from 10μm x 10μm scan width down to 25nm x 25nm. On the scale of 5 - 10nm, we observe corrugations rippled in one dimension. Larger structures are resolved by choosing scan parameters such that vibrational modes are triggered in certain reproducible regions, possibly corresponding to monolayer regions or fragments. Bias voltage ramps are employed for controlled and reversible membrane picking with the observation of flipping processes of the rippled structure.