Doped thin metal oxide films for catalytic gas sensors

TiO2 and Pt doped TiO2 thin films were grown by pulsed laser deposition on 〈0 0 1〉 SiO2 substrates. The doped films were compared with undoped ones deposited in similar experimental conditions. An UV KrF* (λ = 248 nm, τFWHM ≅ 20 ns, ν = 2 Hz) excimer laser was used for the irradiation of the TiO2 or Pt doped TiO2 targets. The substrate temperatures were fixed during the growth of the thin films at values within the 300-500 °C range. The films' surface morphology was investigated by atomic force microscopy and their crystalline quality by X-ray diffractometry. The corresponding transmission spectra were recorded with the aid of a double beam spectrophotometer in the spectral range of 400-1100 nm. No contaminants or Pt segregation were detected in the synthesized anatase phase TiO2 thin films composition. Titania crystallites growth inhibition was observed with the increase of the dopant concentration. The average optical transmittance in the visible-infrared spectral range of the films is higher than 85%, which makes them suitable for sensor applications.