首先介绍了铁电薄膜极化反转疲劳特性测试原理,然后研究了Bi3.54Nd0.46Ti3O12(BNT)铁电薄膜在不同测试频率下的极化反转时的疲劳特性.采用溶胶-凝胶法在Pt/Ti/SiO2/Si衬底上制备了BNT薄膜,发现其极化反转时的疲劳特性与外加测试频率之间存在着极强的依赖关系.研究表明BNT薄膜抗疲劳特性随测试频率减小而变差.在外加反转电场强度为2倍矫顽场强时,测试频率分别为50 kHz1、00 kHz和1 MHz的情况下,经过6.7×108次极化反转后,薄膜的剩余极化值分别下降了36.1%、16.9%和7.1%.在相同条件下,测试了目前铁电存储器用的PbZr0.52Ti0.48O3(PZT)薄膜的疲劳特性,并与BNT的相比较,发现BNT薄膜的抗疲劳特性要明显优于PZT薄膜.文中对上述实验现象作了初步的解释.
The principle to measure the fatigue properties during polarization switching of the ferroelectric films was firstly introduced.Bi3.54Nd0.46Ti3O12(BNT)films on Pt/Ti/SiO2/Si substrate were prepared by a sol-gel process and their electric fatigue properties in different measuring frequency were investigated.Study indicated that the electric fatigue property is strongly dependent on external measuring frequency.Typically,the electric fatigue property of BNT films became worse when the measuring frequency became lower.The remanent polarization of the BNT film decreased by 36.1% when switching cycles are 6.7×108,using a measuring frequency of 50 kHz and a switching electric field twice the coercive field.And the corresponding polarization decreased by 16.9% and 7.1%,while the measuring frequency was 100 kHz and 1 MHz,respectively.Compared with PZT film in the same measuring conditions,the BNT films showed better fatigue properties than the PZT films.