自极化铁酸铋薄膜电滞回线和极化稳定性研究

发布时间：2018-11-04 12:27

【摘要】：铁电薄膜在压电和热释电等微电子器件领域具有应用潜力。为获得出色的器件表现,铁电薄膜要先极化。如果制备的薄膜具有自极化,那么器件的制造成本将被显著降低。提升铁电薄膜自极化的稳定性是最近几年铁电领域的研究热点。传统的商用铁电测试系统在表征自极化铁电薄膜方面仍显不足。在低电压下的测试结果并不能反映自极化薄膜的真实极化状态。本论文针对电滞回线的定标问题、自极化稳定性的评估以及提高等开展了系统的研究工作。利用溶胶-凝胶法制备出了具有自极化的BiFeO3薄膜。根据电滞回线的饱和状态提出了合理的低电压下回线的定标方法。研究了延迟时间对回线缺口大小的影响确定了获得铁电畴充分backswitching的最短延迟时间。对比研究了电压测试顺序对电滞回线的影响;分析了高电压测量后薄膜内部缺陷对分布的变化及其对自极化稳定性的影响。对比分析了高电压测试后电容放置20分钟和一天后电滞回线。研究了预极化电压方向对电滞回线的影响,根据矫顽电压和缺口大小的变化分析了自极化稳定性。并从缺陷化学角度解释了自极化稳定性与预极化电压方向之间的关联。基于数据分析结果,提出了合理的提升自极化薄膜稳定性的方法。并提出了一种缺陷对梯度分布的薄膜结构,以进一步提升自极化薄膜的压电和热释电性能。本论文合理利用了电滞回线在测试过程中,高电压对自极化薄膜初始状态的改变,将自极化薄膜在高低电压下的表现进行对比研究,为寻找提升自极化稳定性的方法以及研发压电与热释电器件奠定了理论和实验基础。
[Abstract]:Ferroelectric thin films have potential applications in piezoelectric and pyroelectric microelectronic devices. In order to achieve excellent device performance, ferroelectric thin films must be polarized first. If the film is self-polarized, the fabrication cost of the device will be significantly reduced. In recent years, improving the stability of self-polarization of ferroelectric thin films has been a hot topic in the field of ferroelectricity. The traditional commercial ferroelectric testing system is still insufficient in characterizing self-polarized ferroelectric thin films. The measured results at low voltage do not reflect the true polarization state of the self-polarized films. In this paper, the calibration problem of hysteresis loop, the evaluation of self-polarization stability and the improvement of self-polarization stability are studied systematically. BiFeO3 thin films with self-polarization were prepared by sol-gel method. According to the saturation state of hysteresis loop, a reasonable calibration method for low voltage loop is proposed. The effect of delay time on the gap size of loop is studied to determine the shortest delay time for obtaining full ferroelectric domain backswitching. The effect of voltage measurement sequence on hysteresis loop and the effect of internal defects on the distribution and self-polarization stability of the film after high voltage measurement were studied. The hysteresis loop of the capacitor after high voltage test for 20 minutes and one day later is compared and analyzed. The influence of the direction of prepolarization voltage on the hysteresis loop is studied. The self-polarization stability is analyzed according to the change of coercive voltage and gap size. The relationship between the self-polarization stability and the direction of prepolarization voltage is explained from the point of view of defect chemistry. Based on the results of data analysis, a reasonable method to improve the stability of self-polarized films is proposed. A defect gradient structure is proposed to further improve the piezoelectric and pyroelectric properties of self-polarized films. In this paper, the changes of the initial state of the self-polarized thin film by high voltage during the measurement of hysteretic loop are reasonably utilized, and the performance of the self-polarized film at high and low voltage is compared and studied. It lays a theoretical and experimental foundation for the research and development of piezoelectric and pyroelectric devices.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.2

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