Pulsed laser deposition of anatase and rutile TiO2 thin films

The investigation deals with the preparation of both anatase and rutile thin films from a sintered rutile target of TiO2 by pulsed laser ablation technique. Microstructural characterization of the sintered target was carried out using X-ray diffraction and AC impedance spectroscopy. Thin films of titania were deposited on (111) Si substrates at 673 K in the laser energy range 200-600 mJ/pulse at two different conditions: (i) deposition at 3.5 X 10(-5) mbar of oxygen, and (ii) deposition at an oxygen partial pressure of 0.1 mbar. The influence of laser energy and oxygen addition on the film growth has been studied. X-ray diffraction analysis of the films indicated that the films are single phasic and nano crystalline. Titania films deposited in the energy range 200-600 mJ/pulse at a base pressure of 5 X 10-5 mbar are rutile with particle sizes in the range 5-10 nm, whereas the films formed at the oxygen partial pressure 0.1 mbar are anatase with particle sizes in the range 10-24 run. In addition, at higher energies, a significant amount of particulates of titania are found on the surface of the films. The change in the microstructural features of the films as a function of laser energy and oxygen addition is discussed in relation with the interaction of the ablated species with the background gas. (C) 2007 Elsevier B.V. All rights reserved.