室温下Sol-Gel法制备BiFeO_3薄膜的铁电和介电性

Ferroelecticity and Dielectric Properties of BiFeO_3 Films at Room Temperature by a Sol-Gel Process

采用溶胶-凝胶(Sol-Gel)法,在LaNiO3包覆的SiO2/Si衬底上采用不同退火工艺制备了BiFeO3薄膜。原子力显微镜研究表明,薄膜表面光滑,并由不同大小的晶粒组成。X-射线表明不同样品结晶程度不同,并根据不同的退火工艺分别呈(010)择优取向和随机取向。2种取向的薄膜的双剩余极化强度分别为2.84μC/cm2和2.56μC/cm2。择优取向的薄膜在低频下的介电常数和介电损耗较大,且其薄膜中观察到大漏电流。并对两薄膜的导电机制用空间电荷限制的电导理论进行了分析。

The BiFeO3 films were deposited on LaNiO3 coated SiO2/Si substrates by different annealing technol- ogy by Sol-Gel process. Atom force microscopy shows that the surfaces were smooth and with different crystalline grains for different films. X-ray diffraction patterns indicated that the samples showed different crystallization extent and took （010） preferred orientation and random orientation according to different annealing process. Double rem nant polarizations of 2.84 uC/cm^2 and 2.56uC/cm^2 were observed for the （010） preferred oriented film and random oriented film, respectively. The preferred oriented film had larger dielectric constant and dielectric loss at low frequency. In addition, larger leakage current conduction was observed in the （010） preferred oriented film. The electric conduction mechanism of the two films was analysised in the electric conduction theory of space-charge limitation.