Pt/Na_(0.5)Bi_(0.5)TiO_(3)/La_(0.5)Sr_(0.5)CoO_(3)电容器的结构和铁电疲劳特性

Structural and Fatigue Properties of Pt/Na_(0.5)Bi_(0.5)TiO_(3)/La_(0.5)Sr_(0.5)CoO_(3) Capacitor

采用偏轴磁控溅射法,以单晶钛酸锶(001)SrTiO_(3)(STO)为衬底,不同沉积温度下外延生长了La_(0.5)Sr_(0.5)CoO_(3)(LSCO)氧化物底电极。X射线衍射仪(XRD)和原子力显微镜(AFM)结构表征以及四探针方阻测试结果表明:LSCO薄膜外延(00l)取向最优温度沉积条件为550℃。此外,利用脉冲激光沉积法,以LSCO/STO异质结为模板,构架了Pt/Na_(0.5)Bi_(0.5)TiO_(3)(NBT)/LSCO/STO铁电电容器。XRD和AFM结构表征表明:NBT薄膜为(00l)外延结构。电流密度-电压测试曲线结果表明,室温变为70℃时,Pt/NBT/LSCO异质结漏电流密度有所增加,但未改变导电机制:低压下为欧姆导电和高压下为陷阱的空间电荷限制电流导电。在5 V驱动电压下,室温和70℃时,Pt/NBT/LSCO电容器具有饱和的电滞回线和保持特性,且经过10^(10)翻转后,均未产生疲劳。

The La_(0.5)Sr_(0.5)CoO_(3)(LSCO)oxide bottom electrodes were epitaxially grown on(001)SrTiO_(3)(STO)substrates via off-axis magnetron sputtering at different deposition temperatures.Based on the results of X ray diffraction(XRD),atomic force microscopy(AFM)and four probe square resistance test,the optimal deposition temperature for(00l)epitaxial LSCO films is 550℃.In addition,the Pt/Na_(0.5)Bi_(0.5)TiO_(3)(NBT)/LSCO/STO ferroelectric capacitor was fabricated on LSCO/STO heterostructure via laser pulse deposition.The results indicate that NBT films are(00 l)epitaxial.The leakage current density of Pt/NBT/LSCO heterostructure increases with increasing temperature from room temperature to 70℃.The conduction mechanism is ohmic conduction at low voltage and space charge limited current at a high voltage.At 5 V driving voltage,the Pt/NBT/LSCO capacitor exhibits saturated hysteresis loops and retention characteristics both at room temperature and 70℃ without fatigue after 10^(10) inversion.