Tuning Cu/Diamond Interfacial Thermal Conductance via Nitrogen-Termination Engineering

TL;DR

This paper introduces a nitrogen-termination strategy to enhance the interfacial thermal conductance of Cu/diamond interfaces, utilizing machine learning-driven simulations to reveal atomistic mechanisms and improve heat transfer efficiency.

Contribution

The study develops a machine learning-based approach to engineer nitrogen-terminated diamond surfaces, significantly increasing interfacial thermal conductance and providing insights into phonon transport mechanisms.

Findings

N-termination increases ITC by 21% compared to bare interface.

High-frequency LA phonons are selectively modulated by N-termination.

N-termination tunes heat conduction via surface mass and bonding modifications.

Abstract

Cu-diamond composites are recognized as promising high-thermal-conductivity candidates for electronic cooling, offering tunable properties and competitive cost. However, their performance is significantly limited by the poor Cu/diamond interfacial thermal conductance (ITC). Here, we propose a nitrogen-termination strategy to tune the ITC of Cu/diamond interfaces and unravel atomistic mechanisms by which nitride interlayers tailor phonon transport. Based on the MACE machine-learning interatomic potential (MLIP) framework, we fine-tune the pre-trained MACE-MPA-0 foundation model by incorporating customized C-N-Cu training datasets. Through MLIP-driven lattice dynamics simulations, we demonstrate that an atomically flat N-termination on diamond enhances the ITC by 21% compared to the bare Cu/diamond interface. Mode-resolved phonon spectroscopy reveals that the LA phonons with frequency above 4 THz and wavevectors near {\Gamma}-X and {\Gamma}-U directions are selectively modulated by N-termination engineering. Analyses of local vibrational states and interfacial bonding further indicate that the N-termination on diamond tunes the interfacial heat conduction via surficial mass modification and bonding regulation, as evidenced by variations in LDOS overlap and COHP spectra. These findings open venues for tuning heat transfer across Cu/diamond interfaces via non-metallic modification, which avoids the graphitization issues associated with metallic coatings, and provide novel guidelines for upgrading the phonon-mediated heat transfer in Cu-diamond composites.