Enhanced conductance at interfaces by ballistic thermal injection

抑制基于晶闸管的电子设备的理想操作效率和性能的主要瓶颈之一是无法有效地减轻温度上升。这些器件中异质界面处的热阻是这些有害温升的主要来源。 这项工作将开发新的实验探针，以研究在电子-声子非平衡条件下，金属/半导体界面之间的热传递过程，这是典型的高频电子器件中的近界面。这项工作的动机是假设，一个平行的途径，热传导通过界面是可能的，通过电子，将超过单独的声子界面传导。 这项工作的结果将通知金属/掺杂半导体和金属/栅极氧化物/掺杂半导体界面的设计，以通过弹道热注入最大化电子热导来增强热传导。 该项目将包括几个外展和教育举措，包括在夏洛茨维尔社区每年为K-12设计的本地外展活动，以及本科和研究生课程的增强。该项目的目标是利用最近发现的传热机制-弹道热注入-来操纵电子-声子非平衡条件，以增强传统上表现出高声子热阻的基于半导体的界面的散热。该项目将研究驱动电子-声子相互作用的基本传热机制，这些机制通过开发一种具有中红外波长可调谐性的新型超快泵浦探测系统来实现。 该项目的更广泛的影响在于理解独特的纳米级传热机制，这将导致新的界面设计以降低温度，例如：延迟逻辑器件的摩尔定律的不祥结局;推动热驱动相变存储器的更高存储密度以跟上Kryder定律;在WBG和UWBG功率和RF器件中实现内在可能的功率密度而不受热故障的限制;以及最大化能量转换器件的效率（例如，光伏、热电、电子）。 这项工作的结果将导致新的界面设计概念，以拥抱这种新颖的界面传热机制，这将最终导致更有效的技术。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.