Enhanced conductance at interfaces by ballistic thermal injection

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

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.