Optical properties of dewetted thin silver/gold multilayer films on glass substrates

• We produce silver, gold and alloyed nanoparticle layers on amorphous substrates.
• Thin multilayers were annealed at low temperatures and ambient conditions.
• Alloying at UV–vis–NIR spectra is reported.
• Certain stacking sequences lead to no observable alloying.

Layer systems composed of gold and silver with a maximum total thickness in 15 nm were consecutively sputtered on soda-lime-silica flat glasses. Subsequently, the coated glasses were annealed at a temperature of 400 °C for 1 h in air. This resulted in the formation of tiny, well separated alloyed metal particles on the glass surface. The attributed optical transmission spectra showed a single plasmon resonance peak for alloyed particles. The wavelength of the plasmon resonance is reported in dependence of the thickness of the respective layers of gold and silver. A direct dependence of the stacking sequence, with respect to the contact with the furnace atmosphere was detected. If the upper layer consisted of silver, oxidation occurred and an alloy was not formed.