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 N2 or O2 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° under visible light irradiation and a complete transformation in a superhydrophilic state upon UV irradiation.