Crystallization and microstructure development of sol-gel derived titanium dioxide thin films with single and multiple layers

Sol-gel TiO2 thin films were fabricated at 650 degrees C using sol that was derived from the Ti((OPr)-Pr-i)(4)-diethanolamine-H2O-(PrOH)-Pr-i system. Repeated deposition and rapid heating resulted in columnar grains, whereas slow heating-at a rate of 10 degrees-20 degrees C/min-caused equiaxed grains to form. Slow heating caused the film to crystallize as anatase. The anatase-to-rutile ratio of the rapidly heated film increased with increased deposition thickness and repeated depositions. The tendency of the thicker film to crystallize as rutile during rapid heating was attributed to the rapid grain growth of fine anatase grains.