Ferroelectric properties of chemically synthesized perovskite BiFeO3–PbTiO3 thin films

Abstract

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 °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–xPbTiO3 (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, 0.7BiFeO3-0.3PbTiO3 thin films exhibited the largest remanent polarization, and the remanent polarization (Pr) and coercive field (Ec) at −190 °C were approximately 60 μC/cm2 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 Pr and Ec values of 5 mol % Mn-doped 0.7BiFeO3-0.3PbTiO3 films at room temperature were approximately 40 μC/cm2 and 100 kV/cm, respectively. Potentially large remanent polarization (∼90 μC/cm2) was also demonstrated by the BF-PT thin films.