Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 15: Focused Session: Epitaxial Graphene II

O 15.5: Vortrag

Montag, 23. März 2009, 16:15–16:30, SCH 251

Graphene nanomembranes excited by ac voltages of an STM — •Torge Mashoff¹, Viktor Geringer¹, Tim Echtermeyer², Max Lemme², Marcus Liebmann¹, Marco Pratzer¹, and Markus Morgenstern¹ — ¹II. Institute of Physics, RWTH-Aachen University and JARA-FIT, 52074 Aachen — ²Advanced Microelectronic Center Aachen (AMICA), AMO GmbH, 52074 Aachen

We investigate graphene monolayers deposited on a SiO₂ surface using scanning tunneling microscopy (STM) at ultra-high vacuum and temperatures of 5 K. Depending on the tunneling-voltage it is possible to lift nanometer-sized areas of the partly freely suspended flake by a few 100 pm while still achieving stable STM-measurements. From I(U) and I(z)-spectroscopy data we determine mechanical properties of the nanomembrane such as pretension and Young’s modulus using a model of a parallel-plate capacitor and a clamped circular membrane. These data are in good agreement with previous measurements using atomic force microscopy. Application of an ac voltage leads to oscillations of the nanomembrane which are detected by strongly nonlinear in-phase current oscillations.