Preparation and properties of Ag plasmonic structures on garnet substrates

In this paper technological aspects of preparation of silver nanostructures on garnet substrates and their impact on absorption and photoluminescence have been studied. For this purpose, the changes of plasmonic properties as a function of the Ag NPs preparation features, such as type of substrate material, sputtered silver mass thickness, temperature, and time of thermal treatments were shown. The plasmonic structures were prepared on single-crystalline YAG and GGG garnets as well as amorphous glass substrates by the magnetron sputtering technique. Nucleation and growth of Ag nanoparticles were controlled by a thermal annealing process. Two broad absorption bands peaked at 350–370 nm and 440–650 nm were observed due to quadrupole and dipole modes, respectively, of surface plasmon resonance (SPR) of Ag nanoparticles. Changes of the positions, intensities, and widths of these absorption bands related to the nanoparticle sizes, densities, and shapes are presented. Degradation of the plasmonic structures at ambient conditions, which is revealed as diminishing of the plasmonic absorption bands and associated with sulphidation of Ag nanoparticles in the natural environment, was studied in details. Theoretical simulations of the sulphidation process modelled as coating of Ag nanoparticles with silver sulphide (Ag 2 S) film confirm the experimentally observed diminishing of SPR.