RUI: Acoustic Phonons in Nanostructures: Surface Waves, Thermal Transport, and Imaging

RUI：纳米结构中的声声子：表面波、热传输和成像

• 批准号: 1709521
• 负责人: Brian Daly
• 金额: $ 28.33万
• 依托单位: Vassar College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709521&HistoricalAwards=false
• 关键词: RUI; Acoustic; Phonons; Nanostructures; Surface

Non-Technical AbstractCan laser generated high frequency ultrasound be used to make images of nanostructures buried inside semiconductor devices? It is taken as a given that progress in nanoscale science and technology relies on continuing progress in our ability to make nanoscale images. This project will employ ultrafast lasers that generate light pulses that are less than a millionth of a millionth of a second in duration in order to generate and detect ultrasound that is over 1000 times higher in frequency than medical or industrial ultrasound. The research will entail the use of new 2-Dimensional materials to enhance our ability to detect these ultrasonic waves, and will also broaden our understanding of how such high frequency waves behave as they travel around inside solid semiconductor materials. The project will involve a wide range of undergraduate students in summer research and independent research courses for credit during the semester. It will also enhance a program for incoming freshmen who are under-represented minorities or first-generation college students.Technical AbstractThis project will seek to demonstrate that coherent acoustic phonons can be used to image buried nanostructures. Previous work on this has shown promise, but issues of low signal to noise due to high attenuation of phonons in the 0.1 to 1 THz range have proved daunting. The work will investigate whether 2-D materials such as transition metal dichalcogenides or graphene could prove to be effective transducer layers for a picosecond laser ultrasonic imaging experiment. A second investigation will explore high frequency surface acoustic wave generation and detection by ultrafast optical pump-probe experiments on periodically patterned layered nanostructures. Ultrafast optics has produced the highest surface acoustic wave frequencies ever detected, but a complete understanding of the optical generation and detection is lacking. The work will compare the optical data with computer simulations of the mechanical displacements and the incident/reflected electromagnetic waves. The final component of the project will be a study of phonon attenuation and thermal transport in thin amorphous films and crystals. Time-domain thermoreflectance measurements will be combined with coherent phonon attenuation measurements to form a complete picture of the contribution of long wavelength vibrational modes to thermal transport. Similarly, the measurement of coherent phonon attenuation in crystalline materials, where the thermal conductivity is already well known, will supply important data that may help answer the question of what the behavior of sub-THz phonons says about a material's thermal conductivity.

激光产生的高频超声能用于制作埋在半导体器件内的纳米结构的图像吗？ 人们认为，纳米级科学技术的进步依赖于我们制作纳米级图像的能力的不断进步。 该项目将采用超快激光器，产生持续时间小于百万分之一秒的光脉冲，以产生和检测频率比医疗或工业超声高1000多倍的超声波。 这项研究将需要使用新的二维材料来提高我们检测这些超声波的能力，并且还将扩大我们对这种高频波在固体半导体材料内部传播时的行为的理解。 该项目将涉及广泛的本科生在夏季研究和独立的研究课程的学分在学期。 它还将加强一个程序，为新生谁是代表不足的少数民族或第一代大学生。技术摘要这个项目将寻求证明，相干声学声子可以用来成像埋纳米结构。以前的工作已经显示出希望，但由于在0.1至1 THz范围内声子的高衰减而导致的低信噪比问题已经证明是令人生畏的。这项工作将研究过渡金属二硫属化物或石墨烯等二维材料是否可以证明是皮秒激光超声成像实验的有效换能器层。第二项研究将探索高频表面声波的产生和检测周期性图案化的层状纳米结构的超快光学泵浦探测实验。超快光学已经产生了有史以来检测到的最高表面声波频率，但缺乏对光学产生和检测的完整理解。这项工作将比较光学数据与计算机模拟的机械位移和入射/反射电磁波。该项目的最后一部分将是研究非晶薄膜和晶体中的声子衰减和热输运。时域热反射测量将与相干声子衰减测量相结合，形成一个完整的图片的贡献，长波长的振动模式的热传输。 类似地，晶体材料中相干声子衰减的测量，其中热导率已经众所周知，将提供重要的数据，这些数据可能有助于回答亚太赫兹声子的行为对材料热导率的影响。

项目成果

Picosecond ultrasonic study of surface acoustic waves on periodically patterned layered nanostructures

• DOI: 10.1016/j.ultras.2018.02.013
• 发表时间: 2018-07
• 期刊: Ultrasonics
• 影响因子: 4.2
• 作者: M. Colletta;Wanjiru Gachuhi;Samuel Gartenstein;M. M. James-M.;E. Szwed;B. Daly;W. Cui;G. A. Antonelli

Picosecond laser ultrasonic measurements of interlayer elastic properties of 2H-MoSe2 and 2H-WSe2

• DOI: 10.1016/j.mtchem.2020.100369
• 发表时间: 2020-12
• 期刊: Materials Today Chemistry
• 影响因子: 7.3
• 作者: E. Thompson;E. Manzella;E. Murray;M. Pelletier;J. Stuligross;B. C. Daly;Seng Huat Lee;R. Redwing