Plasma deposition of Au-SiO2 multilayers for surface plasmon resonance based red colored coatings

Nanocomposite thin films with metallic nanoparticles embedded in a dielectric material show attractive plasmonic properties due to dielectric and quantum confinement effects. In this work. the expanding thermal plasma chemical vapor deposition in combination with radjo frequency magnetron sputtering is used to deposit the dielectric-metal multilayers with controlled size and density of NPs, with the purpose of increasing the number density of the nanoparticles at a fixed size and shape of the nanoparticles. The possibility of independently tuning and, therefore, controlling the size and number density of the nanoparticles is used for the fabrication of surface plasmon resonance- based deep colored coatings. The influence of the number of layers, metal surface area coverage in each layer and the thickness of the dielectric layer on the multilayer nanostructure and the relation with the color coating are presented in detail. The nanoparticle size and distribution were measured by means of transmission electron microscopy. Rutherford backscattering and Energy dispersive x-ray spectrum were used to determine the metal surface area coverage. Fourier Transform Infra-Red transmission spectroscopy was used to determine the film chemical composition. Optical properties of the nano-composite layers have been investigated by UV-VIS spectroscopy.