Phonon Spectrum Engineering in Rolled-up Nano- and Micro-Architectures

TL;DR

This paper demonstrates how to engineer the acoustic phonon spectrum in rolled-up nano- and micro-architectures, enabling control over thermal properties for thermoelectric applications.

Contribution

It introduces a novel method for phonon spectrum engineering in multishell tubular structures using self-organization and elastodynamics modeling.

Findings

Number of shells influences phonon dispersion significantly.

Structure dimensions and impedance mismatch are key control parameters.

Potential for thermoelectric applications due to thermal conductivity reduction.

Abstract

We report on a possibility of efficient engineering of the acoustic phonon energy spectrum in multishell tubular structures produced by a novel high-tech method of self-organization of nano- and micro-architectures. The strain-driven roll-up procedure paved the way for novel classes of metamaterials such as single semiconductor radial micro- and nano-crystals and multi-layer spiral micro- and nano-superlattices. The acoustic phonon dispersion is determined by solving the equations of elastodynamics for InAs and GaAs material systems. It is shown that the number of shells is an important control parameter of the phonon dispersion together with the structure dimensions and acoustic impedance mismatch between the superlattice layers. The obtained results suggest that rolled up nano-architectures have potential for thermoelectric applications owing to a possibility of significant reduction of the thermal conductivity without degradation of the electronic transport.