La掺杂BiFeO_3薄膜的铁电性能分析

Ferroelectric properties of La doped BiFeO_3 thin films

为了研究La掺杂BiFeO_3(BLFO)薄膜的铁电性能与频率的相关性,采用溶胶-凝胶法和高通量组合材料技术快速制备了不同La掺杂物质的量分数(0、5%、10%、15%、20%和25%)的BiFeO_3铁电薄膜.利用X线衍射分析仪(XRD)对样品的晶体结构进行分析,并测量掺杂样品的电滞回线(P-E)和漏电流特性(J-V),通过改变测试频率研究Bi_(1-x)La_xFeO_(3±δ)薄膜电学性能的频率依赖性.结果表明:560℃时所有样品均为纯相;在频率为10 k Hz的条件下,La掺杂物质的量分数为15%的样品具有最大的剩余极化值Pr,约为42.2μC/cm^2;电压为1.5 V时,漏电流密度最小,约为0.010A/cm^2;频率为100 Hz时,样品的剩余极化值远小于10k Hz和100k Hz,10 k Hz频率下样品的剩余极化值最大.

In order to study the correlation between ferroelectric properties and frequency in BLFO thin films, the BiFeO3 ferroelectric thin films with different La doped concentrations（0,5%, 10%, 15%, 20% and 25%） were prepared by sol-gel method and high throughput combinatorial technique. The crystal structure of the samples was analyzed by X ray diffraction （XRD）, and the hysteresis loop （P-E） and the leakage current characteristic （J-V）of the doped sample were measured. The frequency dependence of ferroelectric hysteresis loops in the Bi1-xLaxFeO3±δ thin films has been studied by changing the frequency. The results showed that all the samples are single phase when annealing temperature is 560 ℃. The sample has the maximum remnant polarization （Pr） which is about 42.2℃/cm2 when the La doped concentration is 15% at the frequency of 10 kHz, and the leakage current density reaches the smallest value of 0.010 A/cm2 when the volt- age is 1.5 V. It is found that the remanent polarization measured at a frequency of 100 Hz is much less than that when frequency is 10 kHz and 100 kHz, and the remanent polarization value is the largest at 10 kHz frequency.