Effect of thermal annealing on grain size and phase changes in magnetron titanium oxide films

Thin TiO2 films were produced on single-crystal Si-wafers by magnetron sputtering. Subsequently, they were annealed in air at different temperatures. We researched the structure, the phase composition, the morphology, and the dimensional characteristics of the films before and after annealing using X-ray diffraction, energy-dispersive and spectrophotometric analysis, scanning electron microscopy, and small-angle X-ray scattering. The analysis of the influence of annealing parameters on the characteristics of TiO2 films is carried out. The technique for determining the qualitative and quantitative phase composition of TiO2 during its polymorphic transformations at high temperature heating has been developed. It was found that TiO2 annealing at 400 ºC leads to crystallization of the anatase phase, and annealing at 600 ºC leads to transformations into the rutile phase. The optical band gap decreases with increasing temperature and with increasing annealing time.