退火温度对Sol-gel法制备的BiFeO3薄膜结构及电性能的影响

Influence of Annealing Temperature on Structure and Ferroelectric Properties of BiFeO_3 Thin Films Prepared by Sol-gel Process

采用溶胶-凝胶法在ITO/glass衬底上制备了BiFeO3薄膜,退火温度分别为500℃和550℃。实验结果表明,550℃退火的薄膜晶粒较大且不均匀,并有杂相产生,薄膜的漏电流较大,没有得到饱和的电滞回线;而在500℃退火的薄膜晶粒较小且均匀,没有杂相产生,相对于550℃退火的薄膜,其漏电流密度降低了约2个数量级,铁电性得到明显增强,剩余极化强度约为40μC/cm2,矫顽场约为75kV/cm,最大的测试电场为130kV/cm。

The sol-gel process is adopted to prepare BiFeO3 films on ITO/glass substrates annealed at 500℃3 and 550℃. The experiment results show that the film annealed at 550℃ has larger, more asymmetric grains and impurity phase. In addition, the unsaturated ferroelectric hysteresis loop is obtained and the leakage current of the film is larger when the one annealed at 550℃, while smaller grains with no impurity phase are observed in the film annealed at 500℃. More intensely ferroelectric property is gained, and the leakage current of the films is reduced for nearly two orders of magnitude than that of the film annealed at 500℃. The ferroelectric properties get enhanced, and the remnant polarization and coercive field are observed to be 40℃/cm^2 and 75kV/cm under 130kV/cm.