Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)

O 60.48: Poster

Wednesday, March 16, 2011, 17:30–21:00, P4

Kelvin probe and atomic force microscopy of pristine and irradiated graphene sheets — •Oliver Ochedowski, Benedict Kleine Bußmann, Sevilay Akcöltekin, and Marika Schleberger — Universität Duisburg-Essen, Lotharstr. 1 47048 Duisburg

We have prepared graphene by mechanical exfoliation on SrTiO3 and TiO2 single crystalline surfaces and transferred them into an Ultra-Hgih-Vacuum system. By using an atomic force microscope and the Kelvin probe technique the contact potential differences (CPD) of graphene are mapped. The CPD is directly linked to the work function and is used to study doping effects induced by the substrate, adsorbates, water as well as laser and particle irradiation.

We show that graphene on SrTiO3 exhibits an accumulation of carriers corresponding to n-type doping and that water underneath the graphene decreases this effect. Irradiating graphene with laser light at a wavelength of 514,5 nm (5 mW, spot size: 1 micrometer^2), leads to a cleaning effect already after 5 minutes, followed by the formation of defects after about 10 minutes. Furthermore, we present KPFM measurements of graphene irradiated with swift heavy ions under glancing angles of incidence.