Influence of precursor solution concentration on the microstructure, leakage current and dielectric tunability of Zn-doped Na0.5Bi0.5TiO3 thin films prepared by metal organic decomposition

Zn-doped Na0.5Bi0.5TiO3 (Zn: NBT) thin films were prepared from precursor solutions with different concentrations (0.08, 0.20 and 0.35 M) via a metal organic decomposition process. The effects of the mole concentration of precursor solution on crystallization and electrical properties were investigated. All the films exhibit polycrystalline perovskite structure. The increasing degree of predominant (110) orientation with the decrease of the concentration is ascribed to the highly diluted of the solution, leading to the local grain-on-grain growth. Compared with other films, the 0.20 M-film exhibits a strong nonlinear dependence of the dielectric constant on the applied voltage due to the improvement of crystallinity and insulating property. Furthermore, the effect of applied voltage on the dielectric tunability for 0.20 M-film is discussed. A higher tunability of 36.8% and figure of merit of 7.4 in Zn: NBT film can be observed at ±16 V and 100 kHz.