Optical Properties of Au Nanoparticle Dispersed TiO₂ Films Prepared by Laser Ablation

Abstract

Au-nanoparticle dispersed TiO₂ (Au/TiO₂) films were prepared by laser ablation using Au-powder mixed TiO₂ (rutile) sintered targets. The Au content in the films was controlled in the range from 3 to 37 mol% by changing the target composition. As-deposited TiO₂ matrix of the films was amorphous-like anatase, and changed to a well-crystallized anatase phase after heat treatments at 1173 K. The diameters of Au nanoparticles increased from 1.5 to 4.1 nm with increasing the heat-treatment temperature from 573 to 1173 K. Optical absorption spectra by surface plasmon resonance from Au nanoparticles were observed in the heat-treated films. The red-shift of absorption peak from 590 to 635 nm was observed due to the increase in the diameter of Au nanoparticles and refractive index of TiO₂ matrix with increasing the heat-treatment temperature.