Structural and Optical Properties Evolution of Au/SiO2 Nanocomposite Films: The Influence of Substrate Temperature and Thermal Annealing

Abstract

Au/SiO2 nanocomposite films, studied in this work, were prepared by RF-magnetron sputtering technique on glass substrate at room temperature under two different substrate temperatures (Ts), and subsequent heat treatment. For the deposited sample at TS = 25℃, no apparent surface plasmon resonance peak could be observed. After annealing, optical absorption spectrum of the Au/SiO2 thin films showed a broad absorption band around 500 nm relating to gold nanoparticles without any modification in the position of the SPR and the size of particles. For the series deposited at TS = 400℃, the surface plasmon resonance (SPR) was found at 500 nm. After heat treatment it’s redshift from 500 nm to 503 nm, while the size increases from 2.01 nm to 2.3 nm. We have also shown that, as the AuNPs are embedded in silica films, the small nanoparticles size have a slightly larger expansion coefficient than for bigger one.