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Optical detection and characterization of graphene by broadband spectrophotometry.

Authors :
Gray, Alexander
Balooch, Mehdi
Allegret, Stephane
De Gendt, Stefan
Wang, Wei-E
Source :
Journal of Applied Physics; Sep2008, Vol. 104 Issue 5, p053109, 8p, 1 Black and White Photograph, 1 Diagram, 1 Chart, 6 Graphs
Publication Year :
2008

Abstract

The spectra of optical constants, index of refraction (n), and extinction coefficient (k) of graphene and graphite are obtained in the wavelength range of 190–1000 nm (6.53–1.24 eV) using broadband optical spectrophotometry in conjunction with the Forouhi–Bloomer dispersion relations for n and k. Measurement is made possible by the use of a multilayer substrate consisting of bulk Si and a 3000 Å SiO<subscript>2</subscript> film. The effect of multiple internal reflections between the Si/SiO<subscript>2</subscript> and SiO<subscript>2</subscript>/graphene interfaces amplifies the attenuating effect of the graphene layer, thereby improving the sensitivity of the reflectance measurement by a factor of 27 in the deep ultraviolet region of the spectrum. Maximum sensitivity is observed in the deep ultraviolet region of the spectrum, where a strong peak in the spectrum of the extinction coefficient of graphene is identified. The proposed method enables fast nondestructive angstrom-level thickness measurements of graphene and graphite. In this work, layers ranging in thickness between 3.8 Å (graphene) and 792.8 Å are detected, measured, and characterized. Reflectance spectra of graphene and graphite on Ni, Co, and Fe substrates are calculated. Differences of 1.1%–2.0% between the bare substrate and the graphene on the substrate are predicted in the deep ultraviolet region of the spectrum, which makes graphene detectable and measurable on these substrates. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00218979
Volume :
104
Issue :
5
Database :
Complementary Index
Journal :
Journal of Applied Physics
Publication Type :
Academic Journal
Accession number :
34360609
Full Text :
https://doi.org/10.1063/1.2974096