Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 86: Graphene: Electronic Properties, Structure and Substrate Interaction I
O 86.1: Vortrag
Donnerstag, 23. März 2017, 10:30–10:45, WIL A317
Charge Puddles in Graphene near the Dirac Point — •Sayanti Samaddar1,2,3, Indra Yudhistira4, Shaffique Adam4,5, Hervè Courtois2,3, and Clemens Winkelmann2,3 — 1II. Physikalisches Institut, RWTH Aachen Otto-Blumenthal-Straße, Turm 28 D-52074 Aachen, Germany — 2Université Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France — 3CNRS, Institut NEEL, F-38042 Grenoble, France — 4Centre for Advanced 2D Materials and Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore — 5Yale-NUS College, 16 College Avenue West, Singapore 138527, Singapore
The charge carrier density in graphene on a dielectric substrate such as SiO2 displays inhomogeneities, the so-called charge puddles. Because of the linear dispersion relation in monolayer graphene, the puddles are predicted to grow near charge neutrality, a markedly distinct property from conventional two-dimensional electron gases. By performing scanning tunneling microscopy/spectroscopy on a mesoscopic graphene device, we directly observe the puddles' growth, both in spatial extent and in amplitude, as the Dirac point is approached. Self-consistent screening theory, together with the consideration of the impact of the STM tip as an electric gate, provides a unified description of both the macroscopic transport properties and the microscopically observed charge disorder.