Anisotropic heat conduction in silicon nanowire network revealed by Raman scattering

TL;DR

This paper introduces a novel Raman scattering method with variable laser spot sizes to measure anisotropic thermal conductivities in silicon nanowire arrays, enabling contactless and simultaneous in-plane and cross-plane assessments.

Contribution

It presents a new experimental technique combining Raman scattering and variable laser spots for accurate anisotropic thermal conductivity measurement in nanomaterials.

Findings

Successful application to silicon nanowire arrays

Simultaneous estimation of in-plane and cross-plane conductivities

Correlation between experimental and theoretical thermal resistances

Abstract

Anisotropic nanomaterials possess interesting thermal transport properties because they allow orientation of heat fluxes along preferential directions due to a high ratio (up to three orders of magnitude) between their in-plane and cross-plane thermal conductivities. Among different techniques allowing thermal conductivity evaluation, micro-Raman scattering is known to be one of the most efficient contactless measurement approaches. In this letter, a new experimental approach based on Raman scattering measurements with variable laser spot sizes is reported. Correlation between experimental and calculated thermal resistances of one-dimensional nanocrystalline solids allows simultaneous estimation of their in-plane and cross-plane thermal conductivities. In particular, our measurement approach is illustrated to be successfully applied for anisotropic thermal conductivity evaluation of silicon nanowire arrays.