Effect of Post-Deposition Annealing Treatment on the Structural, Optical and Gas Sensing Properties of TiO<sub>2</sub> Thin Films

Abstract

One of the potential applications of TiO 2 is its use in gas sensor technology. The aim of this work was to study the gas sensing properties of TiO 2 thin films in combination with the effect of post-deposition annealing treatment. Titanium dioxide thin films with thickness 100 nm were prepared by the reactive dc magnetron sputtering. The thin films were deposited on sapphire substrate from a titanium target in an oxygen atmosphere. The samples were then post-annealed in air in the temperature range 600 °C 1000 °C. Crystal structure, surface topography and absorption edge of the thin films have been studied by X-ray Diffraction technique, Atomic Force Microscopy and UV-VIS Spectroscopy. It was found that the phase gradually changed from anatase to rutile, the grain size and roughness tended to increase with increasing post-annealing temperature. The effect of these factors on gas sensing properties was discussed. For electrical measurements comb-like Pt electrodes were prepared by standard photolithography and the films were exposed to different concentrations of H 2 gas up to 10000 ppm in synthetic air at various operating temperatures from 200 °C to 350 °C.