Structural and ferroelectric properties of bismuth ferrite thin films deposited by direct current reactive magnetron sputtering

High quality bismuth ferrite thin films were deposited using in situ layer-by-layer reactive direct current magnetron sputtering. The optimal formation parameters were found in order to achieve the best structural and ferroelectric quality of perovskite thin films without post-annealing. Films were deposited on platinized silicon (Pt/Ti/SiO2/Si) substrates at 400-600 °C temperature using Ti2O seed layer. It was shown that the microstructure and ferroelectric properties depend on deposition temperature. Thin films, formed at 450-550 °C temperature, have dense columnar structure and flat surface. Hysteresis measurements show that all investigated films exhibit ferroelectric properties. The highest coercive field of Ec = 210 kV/cm and of Pr = 115 μC/cm2 was obtained for film deposited at 550 °C. Thin films characterize a leakage current which is conditioned by the space charge limited conduction mechanism. It was shown that the ferroelectric properties are very sensitive to stoichiometry of bismuth ferrate films. Coercive field dependence on frequency measurements shows that two regimes of domain wall motion are presented.