Dramatic increase in the thermal boundary conductance and radiation limit from a Nonequilibrium Landauer Approach

2018/12/19 by Shi, Jingjing, Yang, Xiaolong, Fisher, Timothy S. +1
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)

paper · doi:10.48550/arxiv.1812.07910

Abstract

Thermal boundary conductance (TBC) is critical in many thermal and energy applications. A decades-old puzzle has been that many of the measured TBCs, such as those well characterized across Al/Si and ZnO/GaN interfaces, significantly exceed theoretical results or even the absolute upper limit called the ``radiation limit", suggesting the failure of the theory. Here, we identify that for high-transmission interfaces, the commonly assumed phonon local thermal equilibrium adjacent to the interface fails, and the measurable phonon temperatures are not their emission temperature. We hence develop a ``nonequilibrium Landauer approach" and define the unique ``dressed" and ``intrinsic" TBCs. Combining our approach even with a simple diffuse mismatch model (DMM) nearly doubles the theoretical TBCs across the Al/Si and ZnO/GaN interfaces, and the theoretical results agree with experiments for the first time. The radiation limit is also redefined and found to increase over 100% over the original radiation limit, and it can now well bound all the experimental data.

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