Growth of BiFeO3 thin films by chemical solution deposition: the role of electrodes

Abstract

BiFeO₃ (BFO) thin films were grown by chemical solution deposition on a range of electrodes to determine their role in controlling the phase formation and microstructure of the films. The crystallization on oxide electrodes followed the sequence: amorphous → Bi₂O₂(CO₃) → perovskite, while those on Pt crystallized directly from the amorphous phase. IrO₂ electrodes promoted perovskite phase formation at the lowest temperature and LaNiO₃ additionally induced local epitaxial growth. All compositions exhibited fully coherent Fe-rich precipitates within the grain interior of the perovskite matrix, whereas the incoherent Bi₂Fe₄O₉ second phase was also observed at the grain boundaries of BFO grown on Pt electrodes. The latter could be observed by X-ray diffraction as well as transmission electron microscopy (TEM) but coherent precipitates were only observed by TEM, principally evidenced by their Z contrast in annular dark field images. These data have pronounced consequences for the extended use of BFO films under an applied field for actuator, sensor and memory applications.