Reduced leakage current, enhanced ferroelectric and dielectric properties in Mn-doped BiFeO3 thin film composited with TiO2 layers

The 2 mol% Mn-doped Bi1.05FeO3 (abbreviated as BFOMn, S0), BFOMn composited films with TiO2 layer at the surface of BFOMn (S1), and on the interface between BFOMn film and substrate (S2), as well as at the both sides of the BFOMn film (S3) were prepared on indium tin oxide (ITO)/glass substrates through a chemical solution deposition process. The effects of TiO2 layers deposited at different positions on microstructure, insulating, ferroelectric and dielectric performances are fully investigated. The crystallized perovskite structures without any secondary phases are well maintained in all samples. Increased grain sizes can be achieved with the introduction of TiO2. Among these films, S3 has large average grain size and possesses decreased leakage current density of 7.2 x 10(-5) A/cm(2) under 400 kV/cm, relatively large remanent polarization (P-r) value of 82.3 mu C/cm(2) under 3333 kV/cm at 10 kHz, larger dielectric constant (similar to 330) and smaller dissipation factor (similar to 0.04) at 100 kHz. These results demonstrate that introducing TiO2 layers into appropriate positions can be a feasible way to improve the microstructure and enhance the electrical properties of BFO-based films.