Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 55: Graphene

O 55.9: Poster

Tuesday, March 21, 2017, 18:30–20:30, P2-EG

Analysis of local variations of the electronic properties of monolayer and bilayer graphene/HOPG — •Anne Holtsch and Uwe Hartmann — Universität des Saarlandes, P.O. Box 151150, 66041 Saarbrücken

Cleaving a hopg bulk material can occasionally result in formation of graphene. Compared to other substrates hopg has the advantage that occurring Moiré patterns solely have their origin in rotation of the graphene lattice with respect to the hopg lattice orientation. We investigate the topography of the Moiré superstructure by scanning tunnelling measurement (STM) and changes of the electronic properties of graphene induced by the Moiré pattern and variation in amount of graphene layers using scanning tunnelling spectroscopy (STS).

The formation of a Moiré pattern goes along with corrugation of the graphene sheet. But STM measurements of bilayer graphene where both layers are aligned without rotation but the system itself is rotated towards the substrate do not show any corrugation. A possible Moiré pattern in the lower layer does not permeate to the top layer leading to the conclusion that the occurrence of a Moiré pattern is an effect restricted to the topmost graphene layer.

In a monolayer graphene with corrugation due to a Moiré pattern the distance of the graphene layer to the substrate adjusts the size of a band gap opening. For small distance the monolayer can behave bilayer-like. With increasing distance the size of the band gap decreases.