Thermal boundary resistance from transient nanocalorimetry: a multiscale modeling approach

TL;DR

This paper combines atomistic and macro-physics modeling to analyze thermal boundary resistance at nanoscale interfaces, revealing non-equilibrium effects that challenge traditional lumped models in transient nanocalorimetry.

Contribution

It introduces a multiscale modeling approach that accurately captures nanoscale thermal dynamics and questions the validity of conventional models used in experiments.

Findings

Thermal boundary resistance at Al/Al2O3 interface is 1.4 m^2K/GW.

Non-equilibrium electron and phonon temperatures persist up to nanoseconds.

Traditional lumped models may not accurately interpret transient nanocalorimetry data.

Abstract

The Thermal Boundary Resistance at the interface between a nanosized Al film and an Al_{2}O_{3} substrate is investigated at an atomistic level. A room temperature value of 1.4 m^{2}K/GW is found. The thermal dynamics occurring in time-resolved thermo-reflectance experiments is then modelled via macro-physics equations upon insertion of the materials parameters obtained from atomistic simulations. Electrons and phonons non-equilibrium and spatio-temporal temperatures inhomo- geneities are found to persist up to the nanosecond time scale. These results question the validity of the commonly adopted lumped thermal capacitance model in interpreting transient nanocalorimetry experiments. The strategy adopted in the literature to extract the Thermal Boundary Resistance from transient reflectivity traces is revised at the light of the present findings. The results are of relevance beyond the specific system, the physical picture being general and readily extendable to other heterojunctions.