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

该项目致力于解决与铁电薄膜相关的基本材料科学问题及其作为非易失性存储器的潜在应用。方法是使用并进一步发展扫描力显微镜(SFM)来研究微尺度和纳米尺度上的结构/性质关系。重点研究领域包括：在亚晶水平上重建铁电薄膜和电容器的三维磁畴结构；表征脉冲开关前后的电容磁畴结构，以评估脉冲特性和微结构特征(如薄膜成分、厚度、颗粒尺寸和取向以及缺陷)对开关和磁畴稳定性的影响。预计快速脉冲切换与区域成像的结合将允许对定量切换模型的适用性进行测试。在纳米尺度上表征磁区结构、磁区运动和切换的能力将使人们能够进一步洞察和理解伸缩和内在的可变性问题。这项拟议的研究将SFM(Gruverman)在铁电材料纳米尺度表征方面的专业知识与NCSU(Kingon)功能铁电薄膜合成方面的实力联系起来。这项实验研究将与Argonne国家实验室的S.Streiffer合作，与最近改进的铁电薄膜唯象理论相结合。该项目解决陶瓷和电子材料科学领域的基础研究问题，具有技术相关性。该项目的一个重要特点是高度重视教育，并将研究与教育相结合。该项目为研究生培训、连接处理、局部(纳米级)表征、器件特性和理论提供一流的材料科学研究。此外，基于SPM研究的示范实验将被开发并用于吸引未来的学生，包括未被充分代表的少数族裔，进入材料科学。该研究计划提供了在使用尖端科学设备方面的实践经验的绝佳机会。广泛的资源和协作方面，为从事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. ***