Thermal Boundary Conductance Across Metal-Nonmetal Interfaces: Effects of Electron-Phonon Coupling both in Metal and at Interface

TL;DR

This paper provides a theoretical model for thermal boundary conductance across metal-nonmetal interfaces, incorporating electron-phonon interactions in metal and at the interface, and identifies how different energy transfer channels influence conductance.

Contribution

It introduces an analytic expression for thermal boundary conductance considering multiple electron-phonon coupling channels and their interplay at interfaces.

Findings

The three energy transfer channels can be modeled as a series-parallel resistor network.

The relative contributions of each channel vary among different material interfaces.

Competition among channels determines the overall thermal boundary conductance.

Abstract

We theoretically investigate the thermal boundary conductance across metal-nonmetal interfaces in the presence of the electron-phonon coupling not only in metal but also at interface. The thermal energy can be transferred from metal to nonmetal via three channels: (1) the phonon-phonon coupling at interface; (2) the electron-phonon coupling at interface; and (3) the electron-phonon coupling within metal and then subsequently the phonon-phonon coupling at interface. We find that these three channels can be described by an equivalent series-parallel thermal resistor network, based on which we derive out the analytic expression of the thermal boundary conductance. We then exemplify different contributions from each channel to the thermal boundary conductance in three typical interfaces: Pb-diamond, Ti-diamond, and TiN-MgO. Our results reveal that the competition among above channels determines the thermal boundary conductance.