Abstract
We show that it is possible to prepare and identify ultra-thin sheets of graphene on crystalline substratessuch as SrTiO3, TiO2, Al2O3 and CaF2 by standard techniques (mechanical exfoliation, optical and atomic force microscopy).On the substrates under consideration we find a similar distribution of singlelayer, bilayer and few-layer graphene and graphite flakes as with conventionalSiO2 substrates. Theoptical contrast C of a single graphene layer on any of those substrates is determined by calculating the optical propertiesof a two-dimensional metallic sheet on the surface of a dielectric, which yields values betweenC = −1.5% (G/TiO2)and C = −8.8% (G/CaF2). This contrast is in reasonable agreement with experimental data and is sufficient to makeidentification by an optical microscope possible. The graphene layers cover thecrystalline substrate in a carpet-like mode and the height of single layer graphene onany of the crystalline substrates as determined by atomic force microscopy isdSLG = 0.34 nm and thus muchsmaller than on SiO2.
Published Version
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