Effects of tungsten thickness and annealing temperature on the electrical properties of W–TiO2 thin films

TiO2 thin films were prepared by RF magnetron sputtering onto glass substrates and tungsten was deposited onto these thin films (deposition time 15–60 s) to form W–TiO2 bi-layer thin films. The crystal structure, morphology, and transmittance of these TiO2 and W–TiO2 bi-layer thin films were investigated. Amorphous, rutile, and anatase TiO2 phases were observed in the TiO2 and W–TiO2 bi-layer thin films. Tungsten thickness and annealing temperature had large effects on the transmittance of the W–TiO2 thin films. The W–TiO2 bi-layer thin films with a tungsten deposition time of 60 s were annealed at 200 °C–400 °C. The band gap energies of the TiO2 and the non-annealed and annealed W–TiO2 bi-layer thin films were evaluated using (αhν)1/2 versus energy plots, showing that tungsten thickness and annealing temperature had major effects on the transmittance and band gap energy of W–TiO2 bi-layer thin films.