Tunable thermal conductivity in defect engineered nanowires at low temperatures

TL;DR

This study demonstrates that defect engineering in InAs nanowires significantly reduces thermal conductivity at low temperatures due to phonon localization, with tunability via electrostatic and magnetic fields, offering insights into nanoscale thermal transport.

Contribution

The paper introduces a method to tune thermal conductivity in nanowires through defect engineering and external fields without structural damage, revealing new aspects of nanoscale heat transport.

Findings

Thermal conductivity is three orders of magnitude lower than bulk at 10-50 K.

Electronic surface accumulation layer influences thermal conductivity and can be tuned.

Phonon localization in defect structures reduces thermal transport significantly.

Abstract

We measure the thermal conductivity ($\kappa$) of individual InAs nanowires (NWs), and find that it is 3 orders of magnitude smaller than the bulk value in the temperature range of 10 to 50 K. We argue that the low $\kappa$ arises from the strong localization of phonons in the random superlattice of twin-defects oriented perpendicular to the axis of the NW. We observe significant electronic contribution arising from the surface accumulation layer which gives rise to tunability of $\kappa$ with the application of electrostatic gate and magnetic field. Our devices and measurements of $\kappa$ at different carrier concentrations and magnetic field without introducing structural defects, offer a means to study new aspects of nanoscale thermal transport.