Nanoscale Switching Phenomena and Size Effects in Ferroelectric Thin Films Studied by Scanning Force Microscopy

本项目解决与铁电薄膜及其作为非易失性存储器的潜在应用相关的基础材料科学问题。该方法是使用并进一步发展扫描力显微镜（SFM）来研究微观和纳米尺度上的结构/性质关系。突出的研究领域包括：在亚晶级重建铁电薄膜和电容器的三维畴结构；表征脉冲开关前后的电容器畴结构，以评估脉冲特性和微观结构特征（如薄膜成分、厚度、晶粒尺寸和取向以及缺陷）对开关和畴稳定性的作用。预计快速脉冲开关与域成像的结合将允许测试定量开关模型的适用性。在纳米尺度上表征畴结构、畴运动和开关的能力将使我们能够进一步洞察和理解缩放和内在可变性问题。拟议的研究将SFM （Gruverman）在铁电材料纳米级表征方面的专业知识与NCSU （Kingon）在功能铁电薄膜合成方面的实力联系起来。结合最近改进的铁电薄膜现象学理论的实验研究将与阿贡国家实验室的S. Streiffer合作进行。该项目涉及与技术相关的陶瓷和电子材料科学领域的基础研究问题。该项目的一个重要特点是非常重视教育，并将研究与教育相结合。该项目为研究生培训、连接加工、局部（纳米尺度）表征、器件特性和理论提供经典材料科学研究。此外，基于SPM研究的示范实验将被开发出来，并用于吸引未来的学生，包括代表性不足的少数民族，进入材料科学。该研究计划为使用先进科学设备的实践经验提供了极好的机会。广泛的资源和合作方面，为参与跨学科前沿研究的研究生和本科生提供了特殊的教育和培训机会。＊＊＊

This project address fundamental materials science issues associated with ferroelectric thin films and their potential application as nonvolatile memories. The approach is to use, and further de-velop, scanning force microscopy (SFM) to investigate structure/property relationships on the micro- and nanoscale levels. Salient areas for investigation include: reconstruction of the 3-D domain structure of ferroelectric films and capacitors at the sub-grain level; characterization of capacitor domain structures before and after pulse switching to evaluate the role of pulse charac-teristics and microstructural features such as film composition, thickness, grain size and orienta-tion, and defects, on switching and domain stability. It is expected that the combination of fast pulse switching with domain imaging will allow testing of the applicability of quantitative switching models. The capability to characterize domain structure, domain motion and switching at the nanoscale will allow further insight and understanding of scaling and intrinsic variability issues. The proposed research links expertise in nanoscale characterization of ferroelectric mate-rials by SFM (Gruverman) with strength in synthesis of functional ferroelectric films at NCSU (Kingon). The experimental research in combination with recently refined phenomenological theory for ferroelectric films will be undertaken in collaboration with S. Streiffer of Argonne Na-tional Laboratory. %%% The project addresses fundamental research issues in areas of ceramics and electronic ma-terials science having technological relevance. An important feature of the project is the strong emphasis on education, and the integration of research and education. The project provides clas-sic materials science research for graduate student training, linking processing, local (nanoscale) characterization, device properties, and theory. Additionally, demonstrator experiments, based on SPM research will be developed and used to attract future students, including under-represented minorities, into materials science. The research program provides excellent opportunities for hands-on experience in the use of sophisticated scientific equipment. The broad resources, and collaborative aspects, provide special opportunities for education and training of graduate and undergraduate students involved in interdisciplinary forefront research. ***