Preparation of alloyed and “core-shell” Au/Ag bimetallic nanostructures on glass substrate by solid state dewetting

Abstract

Fine tuning of surface plasmon resonance wavelength of metallic nanostructures is advantageous for the exploitation of plasmons. The wavelength is dependent on size and shape of a monometallic nanostructure, but a better control can be achieved by introduction of a second metal. Au and Ag were used in this work to produce bimetallic nanostructures by method of solid-state dewetting of cathode sputtered thin films due to their compatible chemical properties and lattice parameters. The preparation sequence of the metal deposition and annealing of the deposited layers was altered to obtain distinct alloyed and “core-shell” structures. The morphology of the forming structures was observed by SEM and AFM. UV–Vis spectroscopy confirmed the optical properties of such nanostructures are strongly dependent on the sequence of the metal deposition and annealing. The wavelength of the surface plasmon band maximum varied from 400 to 650 nm depending on the parameters of the preparation process and samples with plasmon resonances of both Au and Ag were obtained at certain conditions of preparation.