CAREER: Acoustic Phonons in 2D Materials

该项目利用激光技术研究声波如何在一类原子级薄的二维（2D）材料中移动，如何利用化学改变这种运动，以及如何利用这些知识来改进技术。声波在固体材料中以“声子”的形式移动，声子的作用就像单个的声音粒子。声子可以携带热量并影响携带电流的电子，影响材料器件和应用。该项目将进一步加深对二维材料声子特性的理解，填补我们基础知识的重大空白。这项工作训练本科生和研究生从事科学和工程方面的工作。教育和更广泛的外展目标包括：(i)开发一个公开的在线布里温光谱数据库，（ii）发起为期一天的年度Sciimpact-East会议，向罗德岛普罗维登斯地区缺乏服务的高中学生和教师介绍科学和技术职业，以及（iii）招募代表性不足的少数民族和女性高中学生和本科生参与科学研究。该奖项支持一个项目，以了解二维（2D）硫族化合物（S, Se, Te）和氧化物材料的声子特性，以匹配我们目前对其电子特性的理解。布里渊激光散射将用于绘制内部合成的二维材料的声子色散关系。将引入新的嵌入化学，通过化学调制层间耦合来系统地控制层间声子的行为。缺陷（空洞、空缺和晶界）将使用化学方法设计成二维材料，以研究它们对基本声子行为的影响。这项工作为全面理解二维硫族化物和氧化物材料中声子的化学控制奠定了基础，并将指导对二维材料未来应用中的力学行为、热传输和器件失效的理解。

Non-Technical Description This project studies how sound waves move in a new class of atomically-thin, two-dimensional (2D) materials using a laser-based technique, how to alter this motion using chemistry, and how to use this knowledge to enhance technologies. Sound waves in solid materials move in the form of "phonons," which act like individual particles of sound. Phonons can carry heat and affect electrons that carry electrical currents, impacting material devices and application. This project will further the understanding of the phonon properties of 2D materials, filling a major gap in our fundamental knowledge. This work trains undergraduate and graduate students for careers in science and engineering. Educational and broader outreach goals include: (i) development of a publicly available online Brillouin spectroscopy database, (ii) initiation of an annual one-day Sciimpact-East conference to introduce underserved high school students and teachers in the Providence, RI area to careers in science and technology, and (iii) recruitment of under-represented minority and female high school students and undergraduates to participate in scientific research.Technical Description This award supports a project to understand the phononic properties of two-dimensional (2D) chalcogenide (S, Se, Te) and oxide materials to match our current understanding of their electronic properties. Brillouin laser light scattering will be used to map the acoustic phonon dispersion relations of 2D materials, synthesized in-house. Novel intercalation chemistries will be introduced toward systematically controlling the interlayer phonon behavior by chemically modulating the layer-to-layer coupling. Defects (voids, vacancies, and grain boundaries) will be engineered into 2D materials using chemical methods for investigating their impact on fundamental phonon behavior. This effort lays the foundation for the complete understanding and the chemical control of phonons in 2D chalcogenide and oxide materials and will guide understanding of mechanical behavior, heat transport and device failure in future applications of 2D materials.