Two kinds of BiFeO3 thin films with different oxygen stoichiometry were

fabricated on (La,Sr)CoO3-coated silicon substrates. A Debye-like dielectric

relaxation was observed in the samples thermally treated at 3Pa oxygen. The

frequency dependence of permittivity of the samples treated at 3Pa oxygen can be

fitted by a model containing the Debye-like dielectric response and the universal

dielectric response. According to the model, the dielectric relaxation can be

ascribed to the oxygen vacancy, and the possible influences from the interfacial

polarization between BiFeO3 and electrodes were excluded by the measurement of

the dielectric responses of BiFeO3 films at different dc biased voltages. The

calculated value of dc electric conductivity in BiFeO3 films from this model has the

same order of magnitude as the published results. These results indicate that the

existence of oxygen vacancy not only influences the leakage performance of

BiFeO3 films but also affects the dielectric properties of BiFeO3. The electrical

performance of BiFeO3 films and devices can be improved by decreasing the

density of oxygen vacancy.

Oxygen-Vacancy-Related Dielectric Relaxation in BiFeO3 Films Grown by Pulsed

Laser Deposition. Y.W.Li, Z.G.Hu, F.Y.Yue, P.X.Yang, Y.N.Qian, W.J.Cheng,

X.M.Ma, J.H.Chu: Journal of Physics D, 2008, 41[21], 215403