UNS: Collaborative Research: Ultrafast Phonon Spectroscopy for Lifetime Measurements of Phonons in 2-D Transitional Metal Dichalcogenides

UNS：合作研究：用于二维过渡金属二硫化物中声子寿命测量的超快声子光谱

• 批准号: 1511199
• 负责人: Mark Siemens
• 金额: $ 21万
• 依托单位: University of Denver
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1511199&HistoricalAwards=false
• 关键词: UNS; Collaborative; Research; Ultrafast; Phonon

1512776 / 1511199Yang, Ronggui / Siemens, MarkIn very thin materials (of a few atoms), the opto-electronic properties can be dramatically different from a macroscopic chunk of the same material that has implications in conducting heat. One of this type of materials is the transition metal dichalcogenides (TMDCs). Further progress in integrating these ultra-thin TMDCs into devices requires full understanding of their heat transfer capability, but the thinness that enables their novel physical properties also prevents the use of traditional characterization techniques. Researchers from the University of Colorado and the University of Denver propose to develop a new technique for measuring the dynamics of phonons which carry heat in TMDCs. Results from this project are expected to yield critical insight into the design of novel materials and devices with desired thermal conduction characteristics. The principal investigators will implement a hands-on program encouraging students to explore scientific questions about lasers and heat transfer. Graduate students will be involved in the research for their graduate degrees.Throughout the recent work on nanoscale thermal transport, phonon mean free path (proportional to phonon lifetime) is a central concept that governs the extraordinary phenomena observed and explored over the past two decades for ultra-low and ultra-high thermal conductivity of nanostructured materials. Although the mean free path and lifetime of carriers are simple kinetic concepts, the first-principle calculations of mean free path and lifetime of phonons are only recently being undertaken. A convincing measurement technique is yet needed to measure frequency-dependent phonon lifetime. The objective of this collaborative research project is to adapt two-dimensional coherent spectroscopy, a high-impact technique used to study electronic coherence, to the measurement of phonon lifetime. To demonstrate the efficacy of this novel technique, the frequency-dependent phonon lifetime in 2-D TMDCs will be measured and compared with the first-principles calculations. Phonon lifetime spectroscopy on monolayer and few-layer TMDCs will yield critical information about the layer-dependence of thermal conductivity and phonon in few-layer TMDCs, which can have immediate impact on the design of 2D TMDC-enabled novel devices.

1512776/1511199杨，荣贵/西门子，Markin非常薄的材料(只有几个原子)，其光电性能可能与具有导热作用的同一材料的宏观块有很大不同。过渡金属二卤化物(TMDCs)是这类材料中的一种。在将这些超薄TMDCs集成到设备中的进一步进展需要充分了解它们的热传递能力，但使其具有新的物理特性的薄性也阻碍了传统表征技术的使用。科罗拉多大学和丹佛大学的研究人员提议开发一种新的技术来测量TMDDC中携带热量的声子的动力学。该项目的结果有望为具有所需导热特性的新型材料和器件的设计带来关键的洞察力。主要研究人员将实施一个实践项目，鼓励学生探索有关激光和热传递的科学问题。研究生将参与研究生学位的研究。在最近关于纳米尺度热输运的工作中，声子平均自由程(与声子寿命成正比)是一个核心概念，它支配着过去20年来观察和探索的纳米材料超低和超高导热系数的非凡现象。虽然载流子的平均自由程和寿命是简单的动力学概念，但声子的平均自由程和寿命的第一性原理计算只是最近才开始进行的。还需要一种令人信服的测量技术来测量与频率相关的声子寿命。这一合作研究项目的目标是使二维相干光谱学--一种用于研究电子相干性的高影响技术--适用于声子寿命的测量。为了证明这一新技术的有效性，我们将测量二维TMDDC中声子的频率相关寿命，并与第一性原理的计算结果进行比较。单层和少层TMDDC的声子寿命谱将提供有关少层TMDDC中热导率和声子与层的关系的关键信息，这将对2D TMDC新型器件的设计产生直接影响。