Doping effect of rare-earth ions on electrical properties of BiFeO3 thin films fabricated by chemical solution deposition

Rare-earth-ion (La and Nd)-doped BiFeO3 (BFO) thin films were fabricated by depositing sol-gel solutions on Pt/Ti/SiO2/Si(100) structures. It was found from X-ray diffraction analysis that BFO thin films were polycrystalline and 5 at. % La and Nd ion dopings did not cause structural changes in the BFO thin films. By 5 at. % La doping in BFO thin films, breakdown field increased and leakage current density in the high-electric-field region decreased, compared with those of undoped BFO thin films. Saturated polarization-electric field curves were obtained for La-doped BFO films at room temperature owing to the decreased leakage current density. At 80 K, the remanent polarization of the Nd-doped thin films was almost the same as that of the undoped film (approximately 90 mu C/cm(2)), whereas that of the La-doped thin films was significantly lower (52 mu C/cm(2)).