Microstructure and percolation threshold characteristics of reactive sputtered Au–TiO2 granular composite films

The Au/TiO2 composite films were prepared by using reactive co-sputtering technique. The size and shape of the embedded Au particles and the absorption spectra of the composite films were investigated by using SEM, XRD, and UV–VIS–NIR spectrophotometer, respectively. The average size of Au particles and the electrical conductivity decrease as the sputtering pressure increases. The normalized conductivity of the films deposited at five different pressures with the Au concentration in the range of 0.15–0.91 were measured. The percolation threshold increases from 0.21 to 0.90 as the sputtering pressure increases from 2 × 10−2 Torr to 9.5 × 10−2 Torr.