【作者】 宋志棠； 任巍； 张良莹； 姚熹；

【Author】 Song Zhitang Ren Wei Zhang Liangying Yao Xi (Electronic Materials Research Laboratory,Xi’an Jiaotong University,Xi’an 710049,China)

【机构】 西安交通大学电子材料与器件研究所；

【摘要】 采用金属有机热分解方法制备了Pb过量的镧钛酸铅(PLT)铁电薄膜。电子探针和俄歇电子能谱证实了过量Pb存在于PLT薄膜中和界面上。薄膜的I(t)曲线研究表明,Pb过量的PLT薄膜中存在有陷阱电荷。过量Pb引起的成分偏析与结构缺陷造成了在薄膜的禁带之间产生了许多从能带中分离出的电子能级,其中在靠近薄膜禁带中心附近的深能级上可俘获自由载流子而形成陷阱电荷。在退极化场的作用下,在畴壁上可聚集自由电荷和陷阱电荷,陷阱电荷对电畴产生钉扎,使得薄膜的电滞回线和C-V曲线出现了异常的束腰和四峰现象,自由电荷可屏蔽内部的退极化电场,从而减小了电畴重新定向的障碍,减轻了陷阱电荷对电畴的钉扎程度。薄膜经短路升温处理后,由畴壁上自由电荷和陷阱电荷的变化导致了电滞回线和C-V曲线的异常程度的变化。更多还原

【Abstract】 An electron probe and an Auger electron spectroscopy were used to analyze the composition of lead lanthanum titanate thin films with excess PbO incorporated prepared by metallo-organic decomposition process.The analysis results show that excess Pb exists in PLT thin film and interface between thin film and bottom electrode.Time t dependence of DC currentⅠ(Ⅰ-t curves) of PLT thin films with excess Pb indicated that there are free charges and trapped charges in the thin films.Both structural and chemical disorders caused by excess Pb create highly localized electronic states in the forbidden gap.These states in middle forbidden gap can capture charge carries which becone trapped charges.A part of the free charges and trapped charges may be accumulated at domain walls under a depolarization field.The trapped charges act as pinning centers and have a strong effect on ferroelectric domains.The abbnormal electric properties such as pinched P-E hysteresis loops and four-peak C-V curves are observed.The free charges can reduce an electrostatic barrier to re-orientation of the domains by screening internal depolarizing fields and enhance the kinetics of domain re-orientation. This reduces the pinning effect caused by tuapped charges.The free charges and trapped charges at domain walls change after heating treatment in the condition of short circuit.This results in change of abnormal level of electric properties.更多还原