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HL: Fachverband Halbleiterphysik

HL 28: Poster Session: Graphen; Transport properties; Transport in high magnetic fields / Quantum Hall effect; Metal-semiconductor hybrid systems

HL 28.2: Poster

Monday, March 11, 2013, 16:00–20:00, Poster A

Preparation of folded graphene layers via atomic force microscope — •Johannes C. Rode, Dmitri Smirnov, Christopher Belke, Hennrik Schmidt, and Rolf J. Haug — Institut für Festkörperphysik, Leibniz Universität Hannover, D-30167 Hannover, Germany

Naturally occurring double-layer graphene consists of two hexagonal lattices in Bernal stacking. We investigate the folding of single-layer graphene via atomic force microscope (AFM) and the properties of thusly created bilayers. The crystal lattices of these are often twisted against each other and form decoupled systems which hold interesting electronic properties like a screening effect and reduced Fermi velocities. Our samples are obtained by micromechanical cleavage of natural graphite and placed on a silicon substrate with a top layer of silicon dioxide. Graphene is located and identified using the optical microscope. Detailed height profiles can then be obtained by AFM, which also serves as a tool to mechanically manipulate the graphene by programmed tip movements. We show AFM-induced folding of graphene on a µm-scale and investigate ways to a controlled preparation of folded samples. These can be electrically contacted and characterized. To interpret the results thoroughly, the geometries must be examined with respect to twist angle and crystallographic orientation.