Electron-Phonon Coupling and Thermal Conductance at a Metal-Semiconductor Interface: First-principles Analysis

TL;DR

This study uses first-principles simulations to analyze heat transfer mechanisms at a titanium silicide-silicon interface, highlighting the comparable roles of electron-phonon and phonon-phonon couplings in thermal conductance.

Contribution

It provides a detailed ab initio analysis of electron-phonon coupling and thermal conductance at a metal-semiconductor interface, which was previously not well understood.

Findings

Electron-phonon coupling strength is comparable to bulk metal coupling.

Electron-phonon contribution to interfacial conductance is similar to phonon-phonon conductance.

First-principles calculations effectively estimate interfacial heat transfer mechanisms.

Abstract

The mechanism of heat transfer and the contribution of electron-phonon coupling to thermal conductance of a metal-semiconductor interface remains unclear in the present literature. We report ab initio simulations of a technologically important titanium silicide (metal) - silicon (semiconductor) interface to estimate the Schottky barrier height (SBH), and the strength of electron-phonon and phonon-phonon heat transfer across the interface. The electron and phonon dispersion relations of TiSi$_2$ with C49 structure and the TiSi$_2$-Si interface are obtained using first-principles calculations within the density functional theory (DFT) framework. These are used to estimate electron-phonon linewidths and the associated Eliashberg function that quantifies coupling. We show that the coupling strength of electrons with interfacial phonon modes is of the same order of magnitude as coupling of electrons to phonon modes in the bulk metal, and its contribution to electron-phonon interfacial conductance is comparable to the harmonic phonon-phonon conductance across the interface.