Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 31: Poster II

HL 31.58: Poster

Dienstag, 26. Februar 2008, 16:30–19:00, Poster D

Transport Measurements of Graphene — •Hennrik Schmidt, Patrick Barthold, Thomas Lüdtke, and Rolf J. Haug — Institut für Festkörperphysik, Leibniz Universität Hannover, D-30167 Hannover, Germany

We study electronic transport properties of few layer graphene. Similar to a mono layer, even a small stack of a few layers exhibits a strong field effect while changing the type and amount of charge carriers by applying a backgate voltage. Our samples are made by micromechanical cleavage of natural graphite and are deposited on top of a silicon wafer with a 330 nm thick silicon oxide. The flakes are contacted using electron-beam lithography and structured using plasma etching. Our measurments have been carried out in a bath cryostat with temperatures down to 1.5 Kelvin. The electric field effect is measured while changing temperature and magnetic field. Magneto-transport with a applied field up to 13 Tesla shows Shubnikov-de Haas oscillations depending on the backgate voltage and thereby on the carrier concentration. Additionally, the Hall effect was measured. The change of the type of charge carriers from electrons to holes and of their density is observed in both measurements.