STRUCTURAL AND OPTICAL PROPERTIES OF NANO STRUCTURED TiO 2 THIN FILMS PREPARED BY SOL-GEL SPIN COATING TECHNIQUE (original) (raw)

The TiO 2 thin films have been deposited onto ultrasonically cleaned glass substrates by sol gel spin coating technique. Titanium tetra isopropoxide (TTIP), HCl and ethanol was used as a Titania (TiO 2) precursor , catalyst and solvent respectively. The spin coated films were annealed at 300 o C and 400 o C for 2h. The influence of annealing temperature on structural and optical properties of TiO 2 thin films has been studied. XRD analysis confirms that the film was found to be orthorhombic brookite structure at annealing temperature of 400 o C. Crystallite size was calculated by using Scherrer formula and it was found to be 67nm.Energy-dispersive X-ray analysis confirmed the presence of Ti and O elements in the deposited films. The SEM image of the TiO 2 films showed highly uniform, crack free and nano spherical particles of average diameter around 68nm. Optical transmittance was found to decrease with an increase in annealing temperature. The direct optical band gap of film was calculated by using Tauc's method at different annealing temperatures and was found to be in the range of 3.3eV to 3.46eV. The Urbach energy of the film annealed at different temperatures was calculated. The TiO 2 film shows high refractive index 2.52 at a wavelength of 335nm.