Structural and optical properties of sputtered Titania films

Titania thin films have been deposited by the magnetron sputtering method. This process has been used to give improved optical and structural properties such as high refractive index and low defect density. A detailed investigation has been made to study the influence of the combined effect of both deposition conditions (sputtering pressure and r.f. power) and post deposition annealing up to 600 degrees C on the composition, structural and optical properties of the titanium oxide films. The as-deposited films are found to be amorphous. The cristallinity sets by post deposition annealing. The variation in microstructural properties is explained according to the basis of the enhanced mobility of the sputtered particles at high r.f. power and low sputtering pressure. The changes in the stoichiometry are attributed to the preferential sputtering and microstructural evolution. The stresses determined by the bending beam method are found to be compressive, the highest values are obtained in the coatings exhibiting the most dense structure. Both, those structure variations and the deviations from stoichiometry result in a variation in the optical constants of the sputtered films. (C) 1997 Elsevier Science S.A.