Synthesis of undoped and Ni doped InTaO4 photoactive thin films by metal organic chemical vapor deposition

Indium tantalate (InTaO4) and nickel doped InTaO4, In1-xNixTaO4 (x=0.1), thin films were grown by Pulsed Injection Metal Organic Chemical Vapor Deposition (PI-MOCVD). The deposition was carried out using as precursors a solution of Ta(OC2H5)(5) and In(THD)(3) in toluene for the InTaO4 and Ta(OC2H5)(5), In(THD)(3) and Ni(THD)(2) in toluene for the In1-xNixTaO4 thin films. The compounds formation, films stoichiometry and crystalline structure were studied as a function of substrate temperature and precursors concentration. Crystalline and stoichiometric (indium/tantalum atomic ratio of 1) films were obtained under optimized deposition conditions. Post-deposition heat treatment in N-2 or O-2 atmospheres further improved the crystalline quality of the films. Under optimum growth conditions the films showed no phase segregations, a feature that makes them suitable for future photocatalytic applications. The study of hydrophilic activities of In1-xNixTaO4 thin films evidenced a decrease of the water contact angle up to 60 degrees under visible light irradiation and a complete transformation in a superhydrophilic state upon UV irradiation. (C) 2007 Elsevier B.V. All rights reserved.