Abstract
TiO2 films were deposited by DC magnetron sputtering under various discharge gas pressures and annealed at various temperatures. The structure of the films was investigated with focus on porosity, which was evaluated quantitatively by density and effective surface area. Furthermore, the H2 sensing property of the films was investigated at various operating temperatures in ambient air. As the pressure during deposition increased, pores developed between columnar grains. In the most porous film deposited at 12 Pa, the sidewalls of the columnar grains were mostly exposed. A dense film deposited under a low pressure showed sensitivity only at an operating temperature above 200°C. As the porosity increased, the sensing temperature decreased. A porous film annealed at 500°C showed a rather high sensitivity even at a low temperature of 100°C.
