Interfacial thermal resistance between porous layers: impact on thermal conductivity of a multilayered porous structure

TL;DR

This study investigates the interfacial thermal resistance in multilayered porous silicon nanostructures, revealing its significant impact on overall thermal conductivity and providing the first experimental evaluation of this resistance.

Contribution

It introduces the first experimental measurement of interfacial thermal resistance in multilayered porous silicon structures and highlights its crucial role in thermal transport.

Findings

Experimental thermal conductivity values are lower than theoretical predictions.

Interfacial thermal resistance significantly affects heat transfer in multilayered porous structures.

Elastic mismatch causes phononic interface resistance impacting thermal transport.

Abstract

Features of thermal transport in multilayered porous silicon nanostructures are considered. Such nanostructures were fabricated by electrochemical etching of monocrystalline Si substrates by applying periodically changed current density. Hereby, the multilayered structures with specific phononic properties were formed. Photoacoustic (PA) technique in gas-microphone configuration was applied for thermal conductivity evaluation. Experimental amplitude-frequency dependencies were adjusted by temperature distribution simulation with thermal conductivity of the multilayered porous structure as a fitting parameter. The experimentally determined values of thermal conductivity were found to be significantly lower than theoretically calculated ones. Such difference was associated with the presence of thermal resistance at the interfaces between porous layers with different porosities arising because of elastic parameters mismatch (acoustical mismatch). Accordingly, the magnitude of this interfacial thermal resistance was experimentally evaluated for the first time. Furthermore, crucial impact of the resistance on thermal transport perturbation in a multilayered porous silicon structure was revealed.