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arXiv · 1210.0575

Determination of the Optical Index for Few-Layer Graphene by Reflectivity Spectroscopy

Behnood G. Ghamsari·Jacob Tosado·Mahito Yamamoto·Michael S. Fuhrer·Steven M. Anlage
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Abstract

We have experimentally studied the optical refractive index of few-layer graphene through reflection spectroscopy at visible wavelengths. A laser scanning microscope (LSM) with a coherent supercontinuum laser source measured the reflectivity of an exfoliated graphene flake on a Si/SiO2 substrate, containing monolayer, bilayer and trilayer areas, as the wavelength of the laser was varied from 545nm to 710nm. The complex refractive index of few-layer graphene, n-ik, was extracted from the reflectivity contrast to the bare substrate and the Fresnel reflection theory. Since the SiO2 thickness enters to the modeling as a parameter, it was precisely measured at the location of the sample. It was found that a common constant optical index cannot explain the wavelength-dependent reflectivity data for single-, double- and three-layer graphene simultaneously, but rather each individual few-layer graphene possesses a unique optical index whose complex values were precisely and accurately determined from the experimental data.

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Behnood G. Ghamsari, Jacob Tosado, Mahito Yamamoto, Michael S. Fuhrer, Steven M. Anlage. 2012-10-01. Determination of the Optical Index for Few-Layer Graphene by Reflectivity Spectroscopy. https://doi.org/10.1038/srep34166

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