Enhanced conductance at interfaces by ballistic thermal injection

制约半导体电子产品理想运行效率和性能的主要瓶颈之一是无法有效地缓解温度上升。这些器件中异质界面的热阻是这些有害温升的主要来源。这项工作将开发新型的实验探头来研究高频电子器件中典型的近界面电-声子非平衡条件下金属/半导体界面的热传递过程。这项工作的动机是假设一条平行的界面热传导路径是可能的，它通过电子而不仅仅是声子界面传导。这项工作的结果将为金属/掺杂半导体和金属/栅氧化物/掺杂半导体界面的设计提供参考，通过弹道热注入最大限度地提高电子的热导来增强热传导。该项目将包括若干外联和教育举措，包括每年在夏洛茨维尔社区为K-12设计的一次地方外联活动，以及加强本科生和研究生的课程。该项目的目标是利用最近发现的一种热传递机制-弹道热注入-来操纵电子-声子非平衡的条件，以增强传统上表现出高声子热阻的半导体界面的散热。这个项目将研究驱动界面上和界面附近的电子-声子相互作用的基本热传递机制，这是通过开发一种新型的波长可调到中红外的超快泵浦-探测系统来实现的。该项目更广泛的影响在于对独特的纳米级传热机制的理解，该机制将导致新的接口设计以降低温度，例如，推迟逻辑器件摩尔定律的不祥结局；推动热驱相变存储器中更高的存储密度，以跟上Kryder定律的步伐；在WBG和UWBG功率和射频器件中实现固有的可能功率密度，而不受热故障的限制；以及通过独立设计电气和热载流子来最大限度地提高能量转换器件(如光伏、热电、热电)的效率。这项工作的发现将导致新的界面设计概念来采用这种新的界面热传递机制，这最终将导致更高效的技术。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

One of the primary bottlenecks that is inhibiting the ideal operating efficiency and performance in semiconductor-based electronics is the inability to effectively mitigate temperature rises. The thermal resistances at heterogeneous interfaces in these devices are the primary source of these deleterious temperature rises. This work will develop novel experimental probes to study the heat transfer processes across metal/semiconductor interfaces during conditions of electron-phonon nonequilibrium that are typical near interfaces in high frequency electronic devices. This work is motivated by the hypothesis that a parallel pathway for heat conduction across interfaces is possible via electrons that will exceed phononic interfacial conduction alone. The results of this work will inform the design of both metal/doped semiconductor and metal/gate oxide/doped semiconductor interfaces to enhance thermal conduction by maximizing electron thermal conductance via ballistic thermal injection. This project will encompass several outreach and educational initiatives, including a local outreach event in the Charlottesville community annually designed for K-12, and curriculum enhancement at both undergraduate and graduate levels. The goal of this project is to leverage a recently-discovered heat transfer mechanism – ballistic thermal injection – to manipulate conditions of electron-phonon nonequilibrium to enhance heat dissipation across semiconductor-based interfaces that traditionally exhibit high phonon thermal resistances. This project will study the fundamental heat transfer mechanisms that drive the electron-phonon interaction both across and near interfaces, which is enabled by the development of a novel ultrafast pump-probe system with wavelength tunability into the mid-infrared. The broader impacts of this project are in the understanding of unique nanoscale heat transfer mechanisms that will lead to new interface designs to reduce temperature that can, for example: delay the ominous end to Moore’s Law for logic devices; push to higher storge densities in thermally-driven phase change memory to keep pace with Kryder’s Law; achieve the intrinsically possible power densities in WBG and UWBG power and RF devices without being limited by thermal failures; and maximize efficiency of energy conversion devices (e.g., photovoltaic, thermoelectric, thermionic) through independent engineering of electrical and thermal carriers. The findings from this work will result in new interfacial design concepts to embrace this novel mechanism of interfacial heat transfer, which will ultimately lead to more efficient technologies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.