NIRT: Strain-Enhanced Nanoscale Ferroelectrics

NIRT：应变增强纳米级铁电体

• 批准号: 0507146
• 负责人: Long-Qing Chen
• 金额: --
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0507146&HistoricalAwards=false
• 关键词: NIRT; Strain; Enhanced; Nanoscale; Ferroelectrics

NON-TECHNICAL DESCRIPTION: For many years molecular beam epitaxy (MBE) has been used to build layered semiconductor nanostructures atom-by-atom to investigate and improve our understanding of semiconductor physics and create new devices. These devices (which include laser diodes, high-performance transistors, and magnetic field sensors) have advanced healthcare, national security, communications, entertainment, and transportation-resulting in significant improvements in the quality of life for all Americans. Recent progress in research has demonstrated that this same atom-by-atom synthesis technique can be used to build nanostructures of oxides, including ferroelectrics, with comparable nanometer-scale layering control. Since ferroelectric materials exhibit a wide variety of electrical, optical, and electromechanical properties, they are extensively used in healthcare (e.g., medical ultrasound), national defense (e.g., night vision and sonar systems), and communications (e.g., miniature capacitors for cell phones and computers). The ability to customize the layering of ferroelectric materials at the atomic-layer level and strain them opens exciting possibilities to dramatically enhance their properties. The improved understanding gained via this research will be applied to the development of improved optical and acoustic devices. Future scientists in a highly interdisciplinary research environment in a technologically significant area of national importance will be trained and educated within this program. Professors from Pennsylvania State University, University of Wisconsin, University of Michigan and Rutgers University will run hands-on workshops during the summers at each of the campuses involved in this research team to expose K-12 students to the thrill of science.TECHNICAL DETAILS: The technical objective is to understand the fundamental science underlying the electric, magnetic, and optical responses of strained nanoscale ferroelectrics and multiferroics. An integrated theoretical and experimental effort will be taken. Specifically, "first-principles effective Hamiltonian" approaches based on lattice Wannier functions and Landau-Ginzburg type phenomenological methods will be used to identify ferroelectric and multiferroic materials and heterostructures in which large enhancements in properties are expected with strain. Films will be grown by MBE and laser-MBE, patterned by focused ion beams, and characterized using a combination of x ray diffraction, analytical and transmission electron microscopy, Raman spectroscopy, second harmonic generation, and ferroelectric measurements, all as a function of temperature. Strain is utilized in many semiconductor device structures to improve the transport properties of thin semiconductor layers. Within this project, it will be used to enhance the properties of ferroelectrics. Ferroelectrics are very sensitive to strain and a distinct advantage of thin ferroelectric materials over their bulk counterparts is that they may be strained well beyond where their bulk counterparts would crack. For nanoscale ferroelectrics, huge strains become accessible. This feature combined with the ability to precisely integrate and engineer oxides at the atomic level provides a means to investigate, develop, and exploit the properties of oxides for optical modulators, two-dimensional photonic bandgap structures, and phonon-confining piezoelectric structures relevant to the long-term realization of a phonon laser.

非技术描述：多年来，分子束外延 (MBE) 一直用于逐个原子地构建层状半导体纳米结构，以研究和提高我们对半导体物理的理解并创建新器件。 这些设备（包括激光二极管、高性能晶体管和磁场传感器）具有先进的医疗保健、国家安全、通信、娱乐和交通，从而显着改善了所有美国人的生活质量。 最近的研究进展表明，这种逐个原子合成技术可用于构建氧化物纳米结构，包括铁电体，并具有可比的纳米级分层控制。 由于铁电材料表现出多种电学、光学和机电特性，因此它们广泛应用于医疗保健（例如医疗超声）、国防（例如夜视和声纳系统）和通信（例如电池微型电容器）电话和电脑）。 在原子层水平上定制铁电材料的分层并对它们进行应变的能力为显着增强其性能提供了令人兴奋的可能性。 通过这项研究获得的更好的理解将应用于改进光学和声学设备的开发。 未来的科学家将在该计划内接受培训和教育，在具有国家重要性的技术领域的高度跨学科研究环境中。 来自宾夕法尼亚州立大学、威斯康星大学、密歇根大学和罗格斯大学的教授将在夏季在参与该研究团队的每个校区举办实践研讨会，让 K-12 学生体验科学的乐趣。技术细节：技术目标是了解应变纳米级铁电体和多铁体的电、磁和光响应的基础科学。将采取综合的理论和实验努力。 具体来说，基于晶格 Wannier 函数和 Landau-Ginzburg 型唯象方法的“第一原理有效哈密顿量”方法将用于识别铁电和多铁材料以及异质结构，其中预计性能会随着应变而大幅增强。 薄膜将通过 MBE 和激光 MBE 生长，通过聚焦离子束形成图案，并结合 X 射线衍射、分析和透射电子显微镜、拉曼光谱、二次谐波产生和铁电测量进行表征，所有这些都作为温度的函数。 许多半导体器件结构中都利用应变来改善薄半导体层的传输特性。 在该项目中，它将用于增强铁电体的性能。 铁电体对应变非常敏感，薄铁电材料相对于块状铁电材料的一个明显优势是，它们的应变可能远远超出块状铁电材料破裂的程度。 对于纳米级铁电体，可以实现巨大的应变。 这一特性与在原子水平上精确集成和设计氧化物的能力相结合，提供了一种研究、开发和利用与光学调制器、二维光子带隙结构和声子限制压电结构相关的氧化物特性的方法。声子激光器的长期实现。