Preparation features and electrical properties of Na0.5Bi0.5TiO3 thin films

Анотація

Some special features of Na_0.5Bi_0.5TiO₃ (NBT) thin films preparation process and electrical properties of the films are presented. The NBT films were grown on both Pt/sitall and Pt/TiO₂/SiO₂/Si substrates by ex-situ method with high-frequency (13.56 MHz) magnetron deposition. Thermal treatment of the films was carried out in the temperature range 550°С – 700°С in air. Obtained X-ray diffraction data show that annealing at 700°C promotes crystallization of NBT films in ferroelectric perovskite phase with minor inclusions of pyrochlore phase. Dielectric hysteresis (P-E) loops in electric field of 90 kV/cm (50 Hz) and the current density-electric field (J-E) characteristics of the films are investigated. It is found that densities of leakage currents in weak fields depend on the film substrate and are significantly lower for the films deposited on the Pt/sitall structure (~6.9 10^-10 A/cm²) in comparison with the films deposited on the Pt/TiO₂/SiO₂/Si structure (~10^-6 A/cm²). The main mechanisms of leakage currents in thin NBT ferroelectric films and the role of structural defects in charge transfer process are discussed.