Effect of post-annealing on structural and optical properties of gold nanoparticles embedded in silica films grown by RF- sputtering

Abstract

Gold-Silica nanocomposite thin films were prepared by RF-magnetron sputtering technique on glass substrate at room temperature. Subsequent thermal treatment was used to promote nanocluster formation. The prepared samples were characterized by X-ray diffraction and optical absorption spectroscopy. After annealing, an increase of size accompanied by an increase of the lattice constant parameter is observed. A value of the surface stress coefficient of gold is f = 3.20 N/m has been obtained. Broad band absorption, with maximum absorbance at around 500 nm, characteristic of gold nanoclusters was observed after heat treatment. Experimental optical absorption spectra were modeled by the modified Mie theory. The plasmon peak red shift obtained from the simulation curves is compared to the calculated one from the variation of lattice constant parameter.

Keywords: Au nanoparticles, silica films, X-ray diffraction, surface plasmon  résonance, lattice   contraction.