Optical constants of graphene measured by spectroscopic ellipsometry

Abstract

A mechanically exfoliated graphene flake (∼150×380 μ m 2) on a silicon wafer with 98 nm silicon dioxide on top was scanned with a spectroscopic ellipsometer with a focused spot (∼100×55 μ m2) at an angle of 55°. The spectroscopic ellipsometric data were analyzed with an optical model in which the optical constants were parameterized by B-splines. This parameterization is the key for the simultaneous accurate determination of the optical constants in the wavelength range 210-1000 nm and the thickness of graphene, which was found to be 3.4 Å. © 2010 American Institute of Physics.