Crystal structure and ferroelectric properties of rare-earth substituted BiFeO3 thin films

The influence of ion modification using rare-earth cations on crystal structures, along with the insulating and ferroelectric properties of BiFeO3 (BFO) thin films was investigated. Rare-earth-substituted BFO films with chemical compositions of (Bi1.00−xREx)Fe1.00O3 (x=0–0.15, RE=La and Nd) were fabricated on (111)Pt∕TiO2∕SiO2∕(100)Si substrates using a chemical solution deposition technique. A crystalline phase of rhombohedral BFO was obtained by heat treatment in a N2 atmosphere at 500°C for 5min. The crystal anisotropy and the Curie temperature of BFO were degraded continuously with increasing contents of La3+ or Nd3+ cations. Ion modification using La3+ and Nd3+ cations up to x=0.05 lowered the leakage current density of the BFO film at room temperature from approximately 10−3 down to 10−6A∕cm2. A polarization (P)-electrical field (E) hysteresis loop measured at 10K revealed that the intrinsic remanent polarization of La3+- and Nd3+-substituted BFO films with x=0.05 (44 and 51μC∕cm2, respectively) was...