Influence of the graphene substrate on morphology of the gold thin film. Spectroscopic ellipsometry study

• Published in: Applied surface science 2013-10, Vol.283, p.603-611
• Main Author: Kostruba, A.M.
• Format: Article
• Language: English
• Subjects: Bruggeman effective medium approximation; Cluster structure; Clusters; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Drude–Lorentz model; Ellipsometry; Exact sciences and technology; Flakes; Gold; Gold film; Graphene; Mathematical models; Nanostructure; Optical properties; Physics; Spectroscopic analysis; Spectroscopy; Thin films; Variable angle spectroscopic ellipsometry
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2013.06.156

•Gold thin films deposited at the same conditions on quartz and quartz–graphene substrates were studied using spectroscopic ellipsometry.•Structure and morphology of gold films were defined using extended Drude–Lorentz model and Bruggeman effective medium approximation.•We report a strong influence of graphene substrate on the structure, optical properties and average clusters size of the gold film. In metal optics gold assumes a special status because of its practical importance in optoelectronic and nanooptical devices, and its role huge increases when occurs combination of gold with two-dimension materials. We performed spectroscopic ellipsometry measurements on evaporated gold, and gold–graphene nanostructures to determine the optical dielectric function across a broad spectral range from 250 to 1000nm. It was found that the deposition of gold film on the quartz substrate covered by graphene flake leads to significant changes in structural and dielectric properties of thin gold layer. Such changes can be explained by increasing of the gold cluster size. The model fit of the ellipsometric data demonstrates that the bilayer “graphene-gold” nanostructure can be described as a uniform optically homogeneous layer with modified optical properties. We can suggest that graphene flake creates a matrix for epitaxial alignment of the crystalline structure of the gold film during its growing. Effective doping of the graphene by free electrons of the gold clusters tends to decrease the optical contrast at the graphene-gold interface.