Nanoscale thermal processes in devices

设备中的纳米级热过程

• 批准号: 1407967
• 负责人: Kevin Pipe
• 金额: $ 36万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1407967&HistoricalAwards=false
• 关键词: Nanoscale; thermal; processes; devices

Thermal management is a significant concern for current and emerging electronic devices, which increasingly operate with high power densities and dissipate power into ever-smaller volumes. Furthermore, devices are increasingly composed of numerous material interfaces, which strongly impact the flow of heat and cause literature values of a device material's thermal conductivity to be more and more irrelevant when describing how heat is transferred from the device. Using a recently developed tool that can map the temperature in a device with unprecedented spatial resolution, the research team will study heat dissipation in fundamental device building blocks such as material junctions as well as critical technologies such as high-power transistors and lasers. From measured temperature profiles, the team will develop general design principles for better managing heat in devices, which can provide better performance and better reliability for numerous device types including light-emitting diodes, lasers, transistors, solar cells, and thermoelectric generators/coolers. From a broad perspective, these advances will aid the performance of technology platforms such as mobile electronics, communications systems, and energy harvesting systems. This work will also train undergraduate and graduate students on the topics of device physics, nanoscale energy transport, and solid state physics, through direct research activities as well as developed course materials. Furthermore, the team will engage high school students and underrepresented minorities in science and engineering activities related to energy and electronic devices.The goal of this project is to use high-resolution thermal measurements in conjunction with coupled electron/phonon models to obtain fundamental insight into the processes that govern nanoscale thermal transport in devices. Such devices increasingly operate with high fields and high power densities, leading to electron, optical phonon, and acoustic phonon systems that are often out of thermal equilibrium with each other. Furthermore, material interfaces can strongly impact phonon scattering and phonon dispersion. While the implications of non-equilibrium on heating in nanoscale devices (especially Si FETs) have been studied computationally for over a decade, most of the proposed models and the large number of assumptions made within them remain experimentally untested due to a lack of instruments that can directly probe temperature fields with nanometer resolution. The research team will utilize an ultra-high vacuum scanning thermal microscope they have recently developed that is capable of probing temperature fields with unprecedented spatial resolution (10 nm) and temperature resolution (15 mK). This tool will provide the first experimental insight into the temperature fields in biased devices, and in conjunction with electron and phonon transport models will reveal the nature of electron-phonon and phonon-phonon coupling at device junctions and hotspots. The study will begin by first probing biased single heterojunctions and homojunctions, and will then expand to prototypical devices such as p-n diodes, diode lasers, and HEMTs. The understanding gained by the proposed work will enable device engineers to better analyze bottlenecks to device heat dissipation, engineer thermoelectric refrigeration within a device, and better engineer electron-phonon scattering for processes such as phonon-assisted tunneling and nonradiative transitions.

热管理是当前和新兴电子设备的一个重要问题，这些设备越来越多地以高功率密度运行，并将功率分散到越来越小的体积中。此外，器件越来越多地由许多材料界面组成，这强烈地影响了热的流动，并导致在描述热从器件传递的方式时，器件材料的导热系数的文献值变得越来越不相关。使用最近开发的一种工具，可以以前所未有的空间分辨率绘制设备中的温度，研究团队将研究基本设备构建块(如材料结)以及关键技术(如大功率晶体管和激光)的散热。根据测量的温度分布，该团队将制定一般设计原则，以更好地管理设备中的热量，这可以为包括发光二极管、激光器、晶体管、太阳能电池和热电发电机/冷却器在内的多种设备类型提供更好的性能和更好的可靠性。从广泛的角度来看，这些进步将有助于移动电子、通信系统和能源收集系统等技术平台的表现。这项工作还将通过直接的研究活动和开发的课程材料，在设备物理、纳米级能量传输和固体物理方面培训本科生和研究生。此外，该团队将让高中生和代表不足的少数族裔参与与能源和电子设备有关的科学和工程活动。该项目的目标是使用高分辨率的热测量与电子/声子耦合模型来获得对控制设备中纳米尺度热传输的过程的基本见解。这样的器件越来越多地以高场和高功率密度运行，导致电子、光学声子和声学声子系统经常彼此失去热平衡。此外，材料界面对声子散射和声子色散有很大的影响。虽然非平衡对纳米器件(特别是SiFET)加热的影响已经通过计算研究了十多年，但由于缺乏能够直接探测纳米分辨率的温度场的仪器，大多数提出的模型和其中的大量假设仍然没有得到实验验证。研究小组将利用他们最近开发的超高真空扫描热显微镜，能够以前所未有的空间分辨率(10 Nm)和温度分辨率(15 MK)探测温度场。这一工具将首次提供对偏置器件中温度场的实验洞察，并结合电子和声子输运模型将揭示器件结点和热点处的电子-声子和声子-声子耦合的性质。这项研究将首先从探测偏置的单一异质结和同质结开始，然后扩展到典型的器件，如p-n二极管、二极管激光器和HEMT。通过拟议的工作获得的理解将使设备工程师能够更好地分析设备散热的瓶颈，设计设备内的热电制冷，并更好地设计声子辅助隧道和非辐射跃迁等过程的电子-声子散射。