Ellipsometry of standard and reduced graphene-oxide thin films

Subject of study . This study investigates the thin films of standard and reduced graphene oxide. Aim of study. The aim of this work is to determine the dependence of the optical and morphological parameters of the films on the state of graphene oxide (standard or reduced) using ellipsometry. Method. The components of the polarization vectors were measured, and the ellipsometric angles ψ and Δ were determined. The ellipsometric equation was solved to determine the dispersion dependences of the extinction coefficient k and refractive index n and to estimate the thickness and surface roughness of the films studied. Main results. The dispersion dependences of the parameters n and k in the visible range were determined for thin films of standard and reduced graphene oxide. The thickness and roughness of the graphene-oxide films were shown to decrease after reduction. Practical significance . The ellipsometry results obtained in this work for thin films of standard and reduced graphene oxide enable the use of standard films as antireflection coatings because of their relatively low refractive index and reduced films as reflecting and absorbing electrical contacts because of their increased refractive index ( n up to 2.6) and extinction coefficient ( k up to 1.3). In addition, the proposed method can be used to determine the degree of material reduction.