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arXiv · 1003.2618

Spectroscopic ellipsometry of graphene and an exciton-shifted van Hove peak in absorption

V. G. Kravets·A. N. Grigorenko·R. R. Nair·P. Blake·S. Anissimova·K. S. Novoselov·A. K. Geim
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Abstract

We demonstrate that optical transparency of any two-dimensional system with a symmetric electronic spectrum is governed by the fine structure constant and suggest a simple formula that relates a quasi-particle spectrum to an optical absorption of such a system. These results are applied to graphene deposited on a surface of oxidized silicon for which we measure ellipsometric spectra, extract optical constants of a graphene layer and reconstruct the electronic dispersion relation near the K point using optical transmission spectra. We also present spectroscopic ellipsometry analysis of graphene placed on amorphous quartz substrates and report a pronounced peak in ultraviolet absorption at 4.6 eV because of a van Hove singularity in graphene's density of states. The peak is downshifted by 0.5 eV probably due to excitonic effects.

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V. G. Kravets, A. N. Grigorenko, R. R. Nair, P. Blake, S. Anissimova, K. S. Novoselov, A. K. Geim. 2010-03-12. Spectroscopic ellipsometry of graphene and an exciton-shifted van Hove peak in absorption. https://doi.org/10.1103/physrevb.81.155413

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