Implementation of Ag/ SiO2 nanofilms for metamaterial engineering

Low dimensions of the nanostructured thin films are essential in applications of miniaturized optical systems. Noble metal thin films of different thicknesses (4–10 nm) were obtained by radio frequency magnetron sputtering (rfMS) with controlled morphology. They exhibit optical behavior useful to metamaterial structures with possible applications in space industry. Optimized deposition conditions led to thin films with a good surface morphology, consisting of nanoparticles with dimensions between 6 nm and 11 nm and a surface roughness between 0.7 nm and 1.5 nm, determined by atomic force microscopy measurements. The thickness of thin films was predefined and monitored in situ with a quartz balance, and the deposition rate was 1.6 Å/s – 1.7 Å/s. High-resolution scanning electron microscopy was used to analyze the surface topography of the samples, showing that Ag thin films are uniform and continuous. The analyzed general XPS scans, as well as, high resolution spectra showed the presence of Ag 3d3 and Ag3d5 in the silver nanostructures. XRD diffractograms indicated the Ag thin films are crystalline. It is also highlighted that increasing the thickness of Ag thin films improves the crystallinity of the corresponding thin film. The morphology changes are manifested in the displacement of the diffraction peak and in values of the grain size between 5.1 nm and 6.7 nm, respectively. The obtained Ag thin films have an adequate morphology and metamaterial-like properties.