Liquid phase deposition of iron and cobalt doped TiO2 epitaxial thin films

Abstract

Liquid phase deposition (LPD) is a wet process in which metal oxide thin films can be deposited on substrates via a chemical equilibrium reaction between a metal fluoro-complex and a metal oxide in aqueous solution. In this study, iron and cobalt doped TiO2 anatase thin films were deposited on (001) oriented SrTiO3 single crystal substrates using liquid phase deposition. The process involves the reaction of ammonium hexafluorotitanate and boric acid, in the presence of FeOOH–HF and Co(NO3)2–ethylenediamine (en) for the iron and cobalt doped TiO2 films respectively. Cobalt doping was also attempted by immersing a non-doped TiO2 film in a solution of Co-en ions. XRD shows that the films are c-axis oriented and films epitaxy was confirmed using pole figure measurements. No metallic secondary phases were detected by XRD and XPS. The iron and cobalt doped films are observed to yield room temperature ferromagnetism. The insulating nature of the films suggests that bound magnetic polarons are responsible for the observed ferromagnetism. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)