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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.5: Poster

Tuesday, March 15, 2011, 18:00–21:00, P3

Visibility of graphene on gadolinium and dysprosium oxide thin films — •I. Petrov¹, T. Toader¹, C. Bock¹, U. Kunze¹, A. Milanov², A. Devi², R. A. Fischer², L. Thekkekara³, D. A. Schmidt³, and M. Havenith³ — ¹Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum — ²Anorganische Chemie II, Ruhr-Universität Bochum — ³Physikalische Chemie II, Ruhr-Universität Bochum

In this work we study the visibility of monolayer graphene exfoliated on gadolinium (Gd₂O₃) and dysprosium oxide (Dy₂O₃), respectively. The rare earth oxides are deposited by thermal chemical vapour deposition on top of a highly n-doped silicon substrate. Due to the higher dielectric constant of the rare earth oxides (є_r ≈ 8 − 9) compared to SiO₂ (є_r = 3.9), we expect an improved screening of charged impurities [1] for graphene-based devices and therefore an enhanced charge carrier mobility. In order to identify the monolayer graphene on the rare earth oxides we calculated the contrast as a function of the wavelength for different oxide thicknesses using a Fresnel-law-based model [2]. The thickness of the flakes is measured by atomic force microscopy while the contrast of the flakes for several wavelengths is determined by optical microscopy. Finally, Raman spectroscopy was performed to verify the exact thickness of the graphene flake. The calculated contrast values are in good agreement with the experimental data, proving optical microscopy is reliable identification tool for monolayer graphene.

[1] S. V. Morozov, et al., Phys. Rev. Lett. 100, 016602 (2008).

[2] P. Blake, et al., Appl. Phys. Lett. 91, 063124 (2007).