Fabrication and characterization of compositionally graded Bi1−x GdxFeO3 thin films

An undoped BiFeO3 thin film, Gd doped Bi0.95Gd0.05FeO3 thin film with a constant composition, Gd up-graded doped Bi1−x GdxFeO3 and Gd down-graded doped Bi1−x GdxFeO3 thin films were successfully grown on Pt (111)/Ti/SiO2/Si (100) substrates using a sol-gel and spin coating technique. The crystal structure, ferroelectric and dielectric characteristics as well as the leakage currents of these samples were thoroughly investigated. The XRD (X-Ray Diffraction) patterns indicate that all these thin films consist of solely perovskite phase with polycrystalline structure. No other secondary phases have been detected. Clear polarization-electric field (P-E) hysteresis loops of all these thin films demonstrate that the incorporation of Gd3+ into the Bi site of BFO thin film have enhanced the ferroelectric performance of pure BiFeO3 thin film, and the Gd down-graded doped Bi1−x GdxFeO3 thin film has the best ferroelectric properties. Compared to other thin films, the optimal ferroelectric behavior of the Gd down-graded doped Bi1−x GdxFeO3 thin film results from its large dielectric constant, low dissipation factor and low leakage current.