Prominent ferroelectricity of BiFeO3 thin films prepared by pulsed-laser deposition

Ferroelectric ${\mathrm{BiFeO}}_3$ thin films have been prepared on ${\mathrm{Pt/TiO}}_2/{\mathrm{SiO}}_2/\mathrm{Si}$ substrates in various oxygen pressures of 0.001–0.1 Torr at a temperature as low as 450 °C by pulsed-laser deposition. The crystallinity of the films was studied by x-ray diffraction. X-ray photoelectron spectroscopy showed that the films have a single phase of perovskite ${\mathrm{BiFeO}}_3.$ The ${\mathrm{BiFeO}}_3$ thin films deposited at 0.01–0.1 Torr show good current-density–applied-voltage characteristics. It is obtained from polarization–electric-field characterization that ${\text{2P}}_r$ is about 71.3 $\mu {\mathrm{C/cm}}^2$ and ${\text{2E}}_c$ is 125 kV/cm. Stable current density and saturated ferroelectric hysteresis loop have been observed in ${\mathrm{BiFeO}}_3$ thin films.