Investigation of Nanoscale Thermal Transport Across a Point Constriction In Contact and Within a Sub-10 nm Gap

提案编号：1067441 Pi：Keunhan Park虽然最近出现的基于针尖的热应用实现了前所未有的纳米级成像、数据存储和制造质量，但它们也对纳米级热传输的基本理解产生了强烈的需求，这些热传输跨越具有纳米级间隙或接触的点狭窄。这些技术的空间分辨率取决于针尖诱导的局域温度分布。然而，直接测量纳米尺度的热输运和衬底上的局部温度分布并不成功，主要是因为(1)现有温度计的空间分辨率和灵敏度较差；(2)无法精确地控制针尖-衬底之间的距离低于10 nm；(3)高局部源的精确温度控制和精确的温度测量存在困难。此外，在实际应用的现场环境中，很少有测量和建模同时考虑一种以上的热传递机制。这一提议旨在从根本上了解纳米尺度热能在基片上的点收缩和由此产生的非均匀加热区的传输。为此，将制造和表征空间分辨率小至尖端半径的纳米温度计，即10-50 nm。利用开发的纳米温度计测量局部衬底温度，同时精确控制悬臂梁的温度和尖端位置，悬停在10 nm以下的间隙。一个包括亚连续空气传导、接触处固体传导和近场辐射的多尺度模型将被开发来理解基于针尖的热应用的物理。该项目的成功将提供被加热的针尖和衬底之间通过亚10 nm气隙和接触的纳米尺度热传输的定量测量，以及针尖附近极局部加热区的温度分布。提出的纳米温度计将提供小于50 nm的传感探针，其制造和表征将在热科学和工程界得到很好的认可。加热悬臂梁的小于10 nm间隙控制的系统方法将很容易适用于其他基于AFM的测量和技术，如SthM和纳米制造。此外，针尖和衬底之间的纳米尺度耦合热传输的数值模拟将促进对点约束下纳米尺度热传输的基本理解。广泛的影响：测量和模拟的结果将填补知识空白，并为基于针尖的热应用的进一步发展提供及时的支持。这项研究将为一名研究生和本科生提供培训机会，其中许多人将从代表性不足的学生群体中招募。为了在纳米级教育中产生协同效应，将启动跨学院学期项目。为了鼓励K-12外展活动，将开发一台用乐高积木建造的AFM，并将其用于URI的SILE(科学和数学研究性学习体验)计划。总体而言，这项建议所涉及的研究和教育活动将在促进教学、培训和学习的同时增进对科学技术的理解。

Proposal number: 1067441 PI: Keunhan ParkWhile recently emerging tip-based thermal applications have realized unprecedented quality of nanoscale imaging, data storage, and manufacturing, they have also created strong demands on the fundamental understanding of nanoscale thermal transport across a point constriction with a nanometer scale gap or in contact. The spatial resolution of these technologies is determined by the tip- induced localized temperature distribution. However, direct measurement of nanoscale thermal transport and local temperature distribution on the substrate has not been successful mainly due to (1) poor spatial resolution and sensitivity of currently available thermometers; (2) incapability to precisely control the tip-substrate distance below 10 nm; and (3) the difficulty in the precise temperature control of a highly local source and accurate temperature measurement. Moreover, very few measurement and modeling have considered more than one heat transfer mechanisms together in in-situ environments where real applications take place.This proposal aims to fundamentally understand nanoscale thermal energy transport across a point constriction and resultant non-uniform heated zone of the substrate. To this end, nanothermometers that have a spatial resolution as small as the tip radius, i.e., 10−50 nm will be fabricated and characterized. The local substrate temperature will be measured with the developed nanothermometer while the cantilever is precisely controlled in its temperature and tip position hovering with a sub-10 nm gap. A multiscale model that includes sub-continuum air conduction, solid conduction at the contact, and near-field radiation will be developed to understand the physics in tip-based thermal applications.Intellectual Merit: The success of this project will provide the quantitative measurement of nanoscale thermal transport between a heated tip and substrate across a sub-10 nm air gap and in contact, and temperature distribution of extremely localized heated zone near the tip. Proposed nanothermometers will provide a sensing probe size smaller than 50 nm, fabrication and characterization of which will be well recognized in the thermal science and engineering community. Systematic approaches on the sub-10 nm gap control of heated cantilevers will be readily applicable to other AFM-based metrologies and technologies, such as SThM and nanomanufacturing. In addition, numerical modeling of coupled nanoscale thermal transport between the tip and substrate will advance the fundamental understanding of nanoscale heat transfer across a point constriction.Broader Impacts: The results from the measurements and simulations will fill in a knowledge gap and provide timely support for the further advancement of tip-based thermal applications. The research will provide training opportunities for one graduate student and undergraduate students, many of whom will be recruited from underrepresented group of students. To make synergetic effects in nanoscale educations, inter-institute term projects will be initiated. To encourage K-12 outreach activities, an AFM built with LEGO blocks will be developed and used in the SMILE (Science and Mathematics Investigative Learning Experiences) program at URI. Overall, research and education activities involved in this proposal will enhance scientific and technological understanding while promoting teaching, training, and learning.