Phonons and thermal transport in Si/SiO$_2$ multishell nanotubes: Atomistic study

TL;DR

This study uses atomistic modeling to analyze phonon behavior and thermal conductivity in Si/SiO$_2$ multishell nanotubes, revealing how structural parameters influence heat transport reduction.

Contribution

It provides a detailed atomistic analysis of phonon spectra and thermal transport in multishell nanotubes, highlighting the impact of interface scattering and geometry on thermal conductivity.

Findings

Thermal conductivity can be reduced to 0.2 W/mK at room temperature.

Phonon spectra redistribution decreases phonon group velocity.

Geometrical parameters effectively control phonon thermal transport.

Abstract

Thermal transport in the Si/SiO$_2$ multishell nanotubes is investigated theoretically. The phonon energy spectra are obtained using the atomistic Lattice Dynamics approach. Thermal conductivity is calculated using the Boltzmann transport equation within the relaxation time approximation. Redistribution of the vibrational spectra in multishell nanotubes leads to a decrease of the phonon group velocity and the thermal conductivity as compared to homogeneous Si nanowires. Phonon scattering on the Si/SiO$_2$ interfaces is another key factor of strong reduction of the thermal conductivity in these structures (down to 0.2 W/mK at room temperature). We demonstrate that phonon thermal transport in Si/SiO$_2$ nanotubes can be efficiently suppressed by a proper choice of nanotube's geometrical parameters: lateral cross-section, thickness and number of shells.