Improvement of the 3$\omega$ thermal conductivity measurement technique at nanoscale

TL;DR

This paper enhances the 3ω thermal conductivity measurement method at the nanoscale by employing finite element modeling to improve accuracy for silicon nanomembranes, addressing limitations of traditional analytical models.

Contribution

It introduces a numerical finite element approach to interpret 3ω data, reducing errors caused by conventional analytical approximations in nanoscale thermal measurements.

Findings

Finite element modeling provides a better fit to experimental data.

The method improves measurement reliability for nanostructures.

Comparison shows advantages over traditional analytical models.

Abstract

The reduction of the thermal conductivity in nanostructures opens up the possibility of exploiting for thermoelectric purposes also materials such as silicon, which are cheap, available and sustainable but with a high thermal conductivity in their bulk form. The development of thermoelectric devices based on these innovative materials requires reliable techniques for the measurement of thermal conductivity on a nanometric scale. The approximations introduced by conventional techniques for thermal conductivity measurements can lead to unreliable results when applied to nanostructures, because heaters and temperature sensors needed for the measurement cannot have a negligible size, and therefore perturb the result. In this paper we focus on the 3$\omega$ technique, applied to the thermal conductivity measurement of suspended silicon nanomembranes. To overcome the approximations introduced by conventional analytical models used for the interpretation of the 3$\omega$ data, we propose to use a numerical solution, performed by means of finite element modeling, of the thermal and electrical transport equations. An excellent fit of the experimental data will be presented, discussed, and compared with an analytical model.