Ferroelectric properties of chemically synthesized perovskite BiFeO3-PbTiO3 thin films

Ferroelectric BiFeO3-PbTiO3 thin films with near morphotropic phase boundary composition were synthesized on Pt/TiOx/SiO2/Si substrates by chemical solution deposition. Perovskite BiFeO3-PbTiO3 single-phase thin films were successfully fabricated at 600 degrees C by optimizing several processing conditions, such as the PbTiO3 content. Typical ferroelectric polarization-electric field (P-E) hysteresis loops were observed for (1-x)BiFeO3-xPbTiO(3) (x=0.2, 0.3, 0.4, 0.5) thin films, which contained some leakage current components at room temperature. In the low temperature region, the BiFeO3-PbTiO3 thin films demonstrated improved insulating resistance and exhibited relatively saturated P-E hysteresis loops. Among these films, 0.7BiFeO(3)-0.3PbTiO(3) thin films exhibited the largest remanent polarization, and the remanent polarization (P-r) and coercive field (E-c) at -190 degrees C were approximately 60 mu C/cm(2) and 230 kV/cm, respectively. Furthermore, Mn doping of the BiFeO3-PbTiO3 thin films was effective in changing the dominant leakage current factors and improving the ferroelectric properties of the resultant thin films at room temperature. The P-r and E-c values of 5 mol % Mn-doped 0.7BiFeO(3)-0.3PbTiO(3) films at room temperature were approximately 40 mu C/cm(2) and 100 kV/cm, respectively. Potentially large remanent polarization (similar to 90 mu C/cm(2)) was also demonstrated by the BF-PT thin films.