Improved ferroelectric and leakage current properties of Er-doped BiFeO3 thin films derived from structural transformation

Multiferroic pure and Er-doped BiFeO3 thin films were prepared using a sol-gel technique. The effect of Er-doped concentration on the crystal structure and on the ferroelectric and leakage current properties of BiFeO3 films were studied in detail. The study showed the enhanced ferroelectric polarization and reduced leakage current density that occurred after doping Er. Such improved ferroelectric and leakage properties are attributed to ferroelectric distortion and to the change of leakage current conduction mechanisms derived from the structural transformation that occurred after doping Er. The rhombohedral structure of pure BiFeO3 transforms to the coexistence of tetragonal and orthorhombic symmetry structure as Er-doped concentration x increased gradually to 0.15, then to the orthorhombic structure when x = 0.20. The present work provides an easy method to decrease the leakage current and improve the ferroelectric properties of BiFeO3 films.