Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 71: Poster Session: Graphene / Topological Insulators / Interfaces and Surfaces

HL 71.11: Poster

Wednesday, March 28, 2012, 16:00–19:00, Poster D

Nanoscale control of the dielectric environment of graphene — Vitalij Scenev, •Nikolaj Severin, and Jürgen Rabe — Humboldt Universität Berlin zu Berlin, Institut für Physik, D-12489 Berlin

The quantitative understanding of charge transfer at interfaces and the spatial distribution of the resulting charge carriers is a critical input to electronic device design. Particularly, the performance and reliability of a graphene field effect transistor (FET) can be dominated by the graphene/substrate environment. Electrostatic force microscopy (EFM) is a versatile tool for quantitative and qualitative investigations of electronic properties of surfaces on the nanoscale, providing high spatial resolution, with no need for electrical contacts. We exfoliated graphenes onto muscovite mica under variable relative humidities. Topography images of graphenes reveal flat plateaus of three different heights, which can be attributed to molecular water layers confined between graphene and mica. EFM revealed reproducible surface potential differences between the plateaus. The variation of the surface potential may be attributed to charge transfer between graphene and the underlying substrate and the orientation of polar water molecules within the molecular layers. We show that the water monolayers can modify the interface between graphene and the substrate and may control the doping level of graphene on the nanoscale.