Microstructural characterization of sol-gel derived Ga2O3-TiO2 thin films for gas sensing

Binary TiO2-Ga2O3 thin films were prepared from the sol-gel process. Titanium butoxide and gallium isopropoxide were used as precursor materials. The mixed solution was spun onto the sapphire and silicon substrates at 2500 rpm for 30 s to prepare thin films. The X-Ray Diffraction (XRD) results revealed that the films annealed at a temperature of 500degreesC for 1 hr is gamma-Ga2O3 structure. Scanning Electronic Microscope (SEM) images revealed that the film surface is smooth with grains in a nanometer scale. The film showed good responses to 100 ppm, 1000 ppm and 1% O-2 at an operating temperature of 470degreesC. The resistance of Ga-doped TiO2 film is between the resistances of pure TiO2 and Ga2O3 films. The response of Ga-doped TiO2 thin film is sensitive, fast and stable to oxygen gas.