保持温度对偏轴磁控溅射法制备BiFeO_3薄膜结构和性能的影响

Effect of Retained Temperature on the Structure and Property of BiFeO_3 Thin Film Prepared by Off-axis Magnetron Sputtering Method

本文采用偏轴磁控溅射方法在Pt/TiO2/SiO2/Si(111)基片上制备了多晶BiFeO3(BFO)薄膜,并构架了Pt/BFO/Pt异质结电容器。利用X射线衍射(XRD)、铁电测试仪等手段研究了保持温度对BFO薄膜结构和性能的影响。XRD图谱表明制备的BFO薄膜均为多晶结构,在保持温度400℃±2℃的区间内得到的BFO薄膜不含明显杂相,其它的温度均有明显的杂相。在保持温度为400℃时得到了较为饱和的电滞回线,在900 nm厚度的情况下,剩余极化强度仍可以达到Pr>40μC/cm2,达到了实际应用的要求Pr>10μC/cm2。漏电流拟合机制表明在低场下属于欧姆机制,在高场下比较接近空间电荷限制电流(SCLC)机制。

The polycrystalline BiFeO3 （BFO） thin films were deposited on Pt/TiO2/SiOJSi （111） substrates by off-axis magnetron sputtering at temperature of＇680 ℃. In order to investigate the electronic property, Pt/BFO/Pt heterostructure capacitors was fabricated. The effect of retained temperature on the structural and physical properties of BFO thin film was investigated by X-ray diffraction （XRD） and a ferroelectric tester. XRD result shows that the BFO thin films were polycrystalline, and it is strongly depended on the keeping temperatures. It was found that among the range of the temperatures about 400 ℃＋ 2 ℃ there are pure- phase and polycrystalline BFO films obtained, but other phases unknown appeared during the temperatures out of the range. A good saturated hysteresis loop can be tested for BFO ferroelectric film of 900 nm maintained at 400 ℃ with Pr 〉 40 μC/cm2, which is larger than the standard use of Pr = 10μC/cm2. Meanwhile, it was found that the leakage conduction mechanism of the Pt/BFO/ Pt capacitor satisfied the ohmic conduction behavior at low applied fields and approximately bulk-limited space-charge-limited conduction （SCLC） at the high applied fields.