Hybrid sputtering-remote PECVD deposition of Au Nanoparticles on SiO2 for surface plasmon resonance-based colored coatings

In this paper, a hybrid system consisting of metal nano-particles dispersed on the surface of a dielectric layer is presented: a remote Expanding Thermal Plasma CVD system is used for the deposition of the inorganic (i.e. SiO2) layers from hexamethyldisiloxane/oxygen mixtures in combination with an rf magnetron sputtering tool for the deposition of metallic (i.e. gold) nanoparticles on top of the SiO2 layers. The optical properties of the Au/SiO2 layers have been investigated by means of UV-VIS-NIR variable angle spectroscopic ellipsometry. Rutherford backscattering and transmission electron microscopy were used to determine the film density, the nanoparticle size and its distribution, respectively. The uniform distribution of gold nanoparticles on the surface of the SiO2 layers allows obtaining red- to blue- colored coatings as a consequence of the shift of the surface plasmon resonance band to higher wavelengths, caused by an increase in size of nanoparticles and metal surface coverage.