Anharmonicity strongly enhancing thermal interface conductance: A new anharmonic atomistic Green's function formalism

TL;DR

This paper introduces a new anharmonic atomistic Green's function formalism that captures anharmonic effects at interfaces, revealing significant enhancements in thermal conductance due to inelastic scattering.

Contribution

A rigorous anharmonic AGF model incorporating first-principles force constants for 3-D structures, enabling accurate prediction of interfacial thermal transport.

Findings

Thermal conductance of silicon and aluminum interfaces is significantly increased.

Inelastic scattering channels are opened by anharmonicity, enhancing heat transfer.

The new formalism advances the understanding of anharmonic effects at interfaces.

Abstract

The traditional atomistic Green's function (AGF) was formulated in the harmonic regime, preventing it from capturing the role of anharmonicity in interfacial thermal transport. Incorporating anharmonicity into AGF has long been desired but remains challenging. We developed a rigorous anharmonic AGF model to incorporate anharmonicity at interfaces in 3-D structures with first-principles force constants. Thermal conductance of silicon- and aluminum-based interfaces is significantly enhanced resulting from the new channels opened by inelastic scattering. This work represents a major step forward for AGF and highlights the importance of anharmonicity at the interface.