SGER: Exploring Thermal Interfacial Transport Using Molecular Dynamics and Transient Thermal Reflectance

审查和分析提案编号：CTS-0536744主要研究者： 诺里斯，帕梅拉 哥伦比亚大学提案标题：SGER：利用分子动力学和瞬态热反射探索热界面传输背景：该提案是作为探索性研究（SGER）类别的小额赠款中化学和传输系统部门的主动提交文件收到的，随后分配给热系统计划的热传输和热处理子元素进行审查。 TTTP项目主任阿方索奥尔特加处理的建议。 没有寻求正式的外部审查，因为他们不需要SGER赠款。行动建议是基于当前NSF和计划优先级，预算限制，计划中项目主题的平衡，工作对热系统研究和教育基础设施的可能贡献，以及提案作为SGER活动的适当性。建议的分析和理由：拟议的为期一年的研究将使用理论和实验相结合的方法来研究热界面传输，特别是测量热边界阻力（TBR），并将其与分子动力学模拟进行比较，以提取相同的结果。虽然热界面是利用新发展的非连续方法研究的热工程的第一个领域之一，但其物理性质仍然难以捉摸。在室温或接近室温下直接测量TBR的实验工作很少。PI已经进行了初步的无资金支持的工作，以证明使用一种新的瞬态热反射技术（TTR）的能力，最初开发的薄膜特性的表征。 结果表明，该方法对边界热阻的测量具有良好的灵敏度。 通过对晶体/晶体界面的初步MD模拟，PI小组基于模拟假设，在经典极限中，热输运最好使用热边界电阻来描述，该热边界电阻具有考虑弹性和非弹性声子散射的项。在极限情况下，非弹性散射占主导地位。这些是令人惊讶的结果，首先由PI记录，它们构成了所提出的有希望的工作的基础。 探索性工作的主要目标是通过实验验证使用MD模拟观察到的界面热导的温度依赖性。 它从来没有被实验证明，如果被证明，将是第一个直接证据的弹性和非弹性声子相互作用的贡献在界面上。 界面热导率可以随许多实际设备（如VLSI芯片）的温度偏移而变化一个数量级。 对这些接口进行建模在一些技术中已经变得至关重要。（瞬态热反射技术）尚未在美国广泛使用。这项探索性资助将允许使用这项技术进行短期、高度集中的实验研究（先前用于表征薄膜），以证明其确实可以用于在室温下测量TBR。如果成功，该项目将回答与室温下基本声子相互作用机制有关的重要问题，迄今为止，这些问题只是推测性的，并且是从不太精确的测量中推断出来的。 此外，它将建立TTR技术作为一个新的重要工具，用于表征界面以下连续尺度。 最后，并行MD建模，将被执行将作为高度耦合的非连续建模和实验，这将加速在理解纳米尺度接口physics.With的整体进展的一个例子更广泛的影响，拟议的工作，PI有一个很好的历史包容性和影响的人在她的研究。 虽然该提案没有具体详细说明让本科生参与的计划，但有一个总体计划，将继续采用先前已经证明的将本科生和少数民族学生纳入实验室研究的方法。 直接费用很低，因为实验室已建立完善。

REVIEW AND ANALYSISProposal Number: CTS-0536744Principal Investigator: Norris, PamelaAffiliation: University of VirginiaProposal Title: SGER: Exploring Thermal Interfacial Transport Using Molecular Dynamics and Transient Thermal ReflectanceContext:The proposal was received as an unsolicited submission to the Chemical and Transport Systems Division in the Small Grants for Exploratory Research (SGER) category and was subsequently assigned to the Thermal Transport and Thermal Processing Sub-element of the Thermal Systems Program for review. TTTP Program Director Alfonso Ortega handled the proposal. No formal external reviews were sought, as they are not required for SGER grants.The recommendation for action is based on current NSF and program priorities, budget constraints, the balance of project topics in the program, the likely contribution of the work to the thermal systems research and education infrastructure, and the appropriateness of the proposal as a SGER activity. Analysis and rationale for recommendation:The proposed one-year study will use a combined theoretical and experimental approach to study thermal interfacial transport, specifically to measure the thermal boundary resistance (TBR) and compare it with Molecular Dynamic Simulations to extract the same. Although thermal interfaces were one of the first areas of thermal engineering that were studied utilizing newly evolving non-continuum approaches, their physics remain elusive. There has been little definitive experimental work to directly measure the TBR at or near room temperature. The PI has conducted preliminary unfunded work to demonstrate the ability to use a novel transient thermo-reflectance technique (TTR) developed initially for characterization of thin film properties. They have shown that it has good sensitivity for measurements of the thermal boundary resistance. Through preliminary MD simulations of crystal/crystal interfaces, the PI's group have hypothesized, based on simulations, that in the classical limit, thermal transport is best described using a Thermal Boundary Resistance with a term accounting for both elastic and inelastic phonon scattering. In the limit, the inelastic scattering is dominant. These are surprising results, first recorded by the PI, and they form the basis for the promising work proposed. The primary goal of the exploratory work is to experimentally verify the temperature dependence of the interface thermal conductance observed using MD simulations. It has never been shown experimentally, and if proven, will be the first direct evidence of elastic and inelastic phonon interaction contributions at interfaces. The interface thermal conductance can vary by an order of magnitude with temperature excursions seen by many practical devices, such as VLSI chips. Modeling these interfaces has become critical in several technologies.The Principle Investigator's team has steadily contributed to research in this area, and has perfected a technique (the transient thermo-reflectance technique) that has not been widely utilized in the U.S. This exploratory grant will allow a short-term, highly focused experimental inquiry using this technique (previously used for characterizing thin films), to demonstrate that it can indeed be used for measuring TBR at room temperature. If successful, the project will answer important questions related to fundamental phonon interaction mechanisms at room temperature, that heretofore have only been speculative, and have been inferred from less refined measurements. Furthermore, it will establish the TTR technique as a new important tool for characterizing interfaces below continuum scales. Finally, the concurrent MD modeling that will be performed will serve as an example of highly coupled non-continuum modeling and experiments that will accelerate the overall progress in understanding nano-scale interface physics.With respect to the Broader Impacts of the proposed work, the PI has an excellent history of inclusion and impact on people in her research. Although the proposal is not specific in detailing a plan to involve undergraduate students, there is a general plan to continue the approach of integrating undergraduate students and minority students in laboratory research that has been previously demonstrated. The direct costs are minimal, because the laboratory is well established.Recommendation: AWARD