Preparation of epitaxial TiO 2 films by pulsed laser deposition technique

Abstract

TiO 2 films with anatase and rutile structure were deposited by pulsed laser deposition (PLD) with a Nd/YAG laser under the controlled O 2 atmosphere. Epitaxial anatase films have been successfully prepared on several kinds of oxide substrates with different lattice parameters. Further the high quality epitaxial rutile films were also grown on α-Al 2O 3 (0001) substrate. During the deposition, the substrates were kept at 500°C and exposed to 35 mtorr O 2 gas pressure. The typical thicknesses of epitaxial films were in the range from 200 to 880 nm. The epitaxial films were analyzed by Rutherford backscattering spectrometry (RBS) combined with channeling and X-ray diffraction for the crystallographic relationships with the substrates. The optical properties were characterized in the ultraviolet–visible region employing optical absorption and photoconductivity measurements. The optical band gap energies of anatase and rutile TiO 2 epitaxial films were evaluated to be 3.22 and 3.03 eV, respectively.