Scalable monolayer-functionalized nanointerface for thermal conductivity enhancement in copper/diamond composite

TL;DR

This paper introduces a novel method using self-assembled monolayers (SAM) to significantly improve the thermal boundary conductance and overall thermal conductivity of copper/diamond composites, achieving record-high values.

Contribution

The study demonstrates a scalable SAM functionalization technique that enhances thermal boundary conductance and composite thermal conductivity, validated through experiments and molecular dynamics simulations.

Findings

TBC increased from 27 to 73 MW/m^2-K with SAM.

Thermal conductivity reached 711 W/m-K, the highest among similar composites.

SAM coverage and ordering critically influence TBC enhancement.

Abstract

Aiming at developing high thermal conductivity copper/diamond composite, an unconventional approach applying self-assembled monolayer (SAM) prior to the high-temperature sintering of copper/diamond composite was utilized to enhance the thermal boundary conductance (TBC) between copper and diamond. The enhancement was first systematically confirmed on a model interface system by detailed SAM morphology characterization and TBC measurements. TBC significantly depends on the SAM coverage and ordering, and the formation of high-quality SAM promoted the TBC to 73 MW/m^2-K from 27 MW/m^2-K, the value without SAM. With the help of molecular dynamics simulations, the TBC enhancement was identified to be determined by the number of SAM bridges and the overlap of vibrational density of states. The diamond particles of 210 {\micro\metre} in size were simultaneously functionalized by SAM with the condition giving the highest TBC in the model system and sintered together with the copper to fabricate isotropic copper/diamond composite of 50% volume fraction. The measured thermal conductivity marked 711 W/m-K at room temperature, the highest value among the ones with similar diamond-particles volume fraction and size. This work demonstrates a novel strategy to enhance the thermal conductivity of composite materials by SAM functionalization.