Enhanced optical properties of sol-gel derived TiO2 films using microwave irradiation

Thin films of TiO2 have been deposited on polished quartz substrates at room temperature by sol-gel dip coating technique followed two different annealing treatment methods. One set by conventional annealing at 600 degrees C for 3 h and second set exposure to microwave (2.45 GHz) radiation at 600 W power for 10 min. X-ray diffraction and scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-visible spectroscopy, techniques have been employed to characterize structural, morphological, compositional and optical properties of the microwave exposed and annealed films. Both microwave exposed and annealed films have shown the nanostructured growth of TiO2 anatase phase with grain size ranging from 10 nm to 25 nm. Due to decrease in the grain size there was a blue shift of E-g calculated in direct transition. Refractive index of the film annealed has shown higher value compared to microwave exposed films. Plausible mechanism for the formation of anatase phase of TiO2 on quartz substrates has also been discussed. (C) 2006 Elsevier B.V. All rights reserved.