Pulsed laser deposition of anatase and rutile TiO2 thin films

摘要

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 × 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 × 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 nm. 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.