Dresden 2011 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 64: Organic Thin Films III

DS 64.7: Vortrag

Freitag, 18. März 2011, 15:30–15:45, GER 38

Imaging ellipsometry of graphene — •Peter H. Thiesen¹, Christian Röling¹, and Ulrich Wurstbauer² — ¹Accurion GmbH, Stresemannstr. 30, 37079 Göttingen — ²Physics Department, Columbia University, New York, NY 10027

A graphene monolayer flake on a SiO₂ (300 nm)|Si substrate was characterized. The sample was previously imaged by optical and atomic force microscopy and identified as a graphene monolayer by RAMAN spectroscopy. Ellipsometric contrast micrographs were recorded. Wavelength spectra of Delta and Psi at different angles of incidence were measured, as well as creation of Delta and Psi-maps. As described in literature, the determination of the dispersion function of graphene is done under the assumption of a layer thickness of 0.35 nm but using a Drude oscillator model. The spectra of Delta and Psi of the Graphene crystallites are significantly different from the substrate and the surrounding graphite flakes. The Dispersion function is in good agreement with literature values when using the same layer thicknesses.

Imaging ellipsometry offers the opportunity to measure the optical properties of graphene flakes at sizes typical for micro-mechanical cleavage. Ellipsometric contrast micrographs, in combination with Psi-maps, are promising tools for locating and identifing graphene crystallites. This was shown for the classic SiO₂|Si substrate as well as for GaAs.