Influence of thickness and air annealing on structural, morphological, compositional, electrical properties of sprayed TiO2 thin films

Abstract: TiO2 thin films were prepared by spray pyrolysis technique at a substrate temperature of 350C under optimum conditions. Films have uniform thickness varying from 0.3–6 μm and good adhesion to substrate. The films were characterized by XRD, SEM and EDAX measurements. XRD profile shows poly crystalline nature of films. As deposited films have anatase phase. Transformation from anatase to anatase–rutile mixed phase may be due to annealing at 400C and thickness variation of films. The microstructural properties such as crystallite size, microstrain and dislocation density found to increase due to concentration of lattice imperfections and crystallization of amorphous TiO2 films. SEM micrographs exhibit spherical, square, flower shaped grains and grain boundary formation. EDAX analysis revealed the formation of stoichiometric TiO2 films. Electrical studies show that the films are of n-type nature and increase in resistivity is attributed to surface oxidation and formation of Ti2O3 structure, a perfect insulator.