The effect of sol-gel composition ratio on phase transformation of titanium dioxide under CO2 laser annealing

The sol-gel solution was mixed by tetraisopropyl orthotitanate (TTIP), acetonylacetone, distilled water and alcohol at various molar ratios and coated on p-type silicon substructure for titanium oxide formation. Then the CO₂ laser annealing in air at powers of 0.5, 1.5 and 3.0 W in the defocus mode was performed on the coatings for studying crystallization of titanium oxide. The microstructure and phase transformation of titanium dioxide were examined by X-ray diffraction pattern. Increasing TTIP concentration and decreasing laser power were favorable for anatase phase formation. The grain size of titanium dioxide calculated using Scherrer's formula was between 10 and 32 nm, which increased with increasing laser power. The ANSYS simulation was employed to calculate temperature distribution of films to correlate with phase transformation of titanium dioxide. This sol-gel processing combined with CO₂ laser annealing had advantages of low cost, controllable titanium dioxide phase, selective area annealing, large area fabrication and easy operating at room temperature.