Preparation and optical properties of barium titanate thin films

Barium titanate (BTO) films were prepared by sol–gel spin-coating technique. The crystal structure and optical properties of BTO films have been investigated. The results indicate that the BTO films are single perovskite phase having tetragonal symmetry. The band gap of the BTO films increases with the increasing of layer number and decreasing of solution concentration. The transmittance and band gap of the BTO films annealed at 900 °C is more than that of the BTO films annealed at 700 °C when wavelength is 200–1000 nm. When wavelength is 400–1000 nm, the absorption coefficient α obtained by experiment is higher than that obtained by calculation (close to zero).