Multiferroic BiFeO₃ thin films prepared by using a conventional RF magnetron sputtering method

Multiferroic BiFeO₃ thin films were deposited on Pt/Ti/SiO ₂/Si substrates by rf magnetron sputtering using self-made BFO ceramic targets. The influence of the partial pressure of oxygen (P(O ₂)), as well as the substrate temperature, on the preparation of pure BFO films was studied. BFO thin films with a single perovskite phase were obtained only for a P(O₂) of 0.3 mTorr to 1.5 mTorr at a substrate temperature of 400 °C, with subsequent annealing at 500 °C in a N ₂ ambient. The impurity phase rather than perovskite BFO phase could be easily formed due to the excess Bi content for a low P(O₂) of 0.1 mTorr. A BFO thin film having high c-axis orientation could be obtained for a P(O₂) of 0.3 mTorr, which has the maximum remanent polarization of 5.2 μC/cm². The leakage current behaviors, as well as the magnetic properties, of the BFO films are elucidated by using a compositional analysis of Fe³⁺ and Fe²⁺ ions from the X-ray photoelectron spectroscopy studies.