| Single-phase multiferroic materials, particularly bismuth ferrite (BiFeO 3), have been the focus of a renewed interest in the recent years. BiFeO 3 is unique because it is the only known single-phase material that is multiferroic at room temperature. Therefore, it has enormous potential for applications in spintronic devices, nonvolatile ferroelectric random access memory, microwave technology, sensors and microactuators. Thin BiFeO 3 films have drawn special attention with regards to the potential integration of BiFeO3 into the semiconductor technology and also because they have been demonstrated to exhibit a large polarization that is an order of magnitude higher than the bulk form. Metalorganic chemical vapor deposition (MOCVD) is arguably one of the most suitable techniques for depositing such complex oxide thin films for fabrication of devices at a commercially viable scale. However, the choice of precursors is critical. In this work, a metalorganic iron precursor n-butylferrocene [(C4H9C5H 4)Fe(C5H5)] has been identified that is more suitable than the existing precursors for use in chemical vapor deposition of ferrites or other mixed iron oxides. The iron precursor is a liquid at room temperature having a high vapor pressure and it undergoes clean evaporation without decomposition. The use of this precursor for MOCVD of iron oxide films has been demonstrated. The resulting iron oxide thin films were characterized for structure, morphology, composition and chemical bonding states using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, respectively. Having demonstrated the suitability of this precursor, it was then used to deposit polycrystalline stoichiometric BiFeO3 films by MOCVD. Electrical measurements show that the films exhibit ferroelectric characteristics at room temperature. Magnetic measurements reveal a room-temperature saturation magnetization of ∼8 emu/cm3. Data on magnetic-field dependence of dielectric constant at 18 GHz provide evidence for coupling between the magnetic and dielectric subsystems in the film, indicating potential for application in high-frequency tunable devices. |
