Synthesis, phase transition and optical properties of nanocrystalline titanium dioxide films deposited by plasma assisted reactive pulsed laser deposition

Titanium dioxide (TiO2) thin films with mixed structure of anatase and rutile were deposited by oxygen plasma assisted pulsed laser deposition, and pure rutile nanocrystalline TiO2 was obtained after post-deposition annealing. The surface morphology was examined by field emission scanning electron microscopy. The crystal structure and the crystallite size were determined using X‐ray diffraction. The effects of annealing on the structural evolution and phase transition were examined by Fourier-transform infrared spectroscopy and Raman scattering spectroscopy through the analysis of bonding configurations. A progressive phase transition on annealing temperature occurs above 300 °C, and a transformation to pure rutile phase completes at about 900 °C. The prepared TiO2 thin films show good transparency in the visible to near infrared region with small variations upon annealing while a red shift in band gap is observed due to annealing.