NANOSTRUCTURED THIN FILMS AND TUBES OF TITANIA FOR ROOM TEMPERATURE SENSING OF GASES

The main objective of this work was to study the applicability of Nano porous/Nanocrystalline TiO2 films for serving the growing demand for fast accurate and low cost air quality analysis techniques. The sensitivity of response to variations in microstructure pointed the way to obtain controlled, reproducible and regular microstructures with critical dimensions proportionate with the Debye- length of the oxide. This work aimed to study the sensor properties of thin films of Nanocrystalline Titania and Titania nanotubes at room temperature. Nano porous/Nanocrystalline TiO2 films were fabricated through evaporation driven convection/sol-gel method by controlling the process conditions. We also fabricated ordered TiO2 nanotube arrays by carefully controlling the anodization conditions. TiO2 nanotube arrays were fabricated through potentiostatic anodization of a Ti metal sheet in various electrolyte mediums. The electrolyte mediums consisted of mixtures of acids ranging from HF, HCl, HNO3, H2SO4, H3PO4 and CH3COOH and polar organic solvents like C2H6OS(DMSO) and C2H4(OH)2(Ethylene Glycol) . Well ordered films consisting of TiO2 nanotube arrays (25 μm to 250 μm in length) were obtained. Contacts were deposited on to the annealed samples. Capacitive gas sensors were fabricated and their response to ammonia gas was evaluated