Thermal transport in semiconductor nanotubes

Semiconductor nanotubes present an exciting avenue to create very thin one-dimensional nanostructures using currently available growth techniques. Due to their large surface-to-volume ratio, nanotubes allow for an effective control over thermal energy transfer. Here, we study thermal transport in crystalline nanotubes made of silicon and germanium-alloyed-silicon by developing a methodology that accurately accounts for phonon dynamics in these nanostructures. The flexibility of the proposed approach allows considering the two nanotube boundaries as distinct from one another and is used to analyze the impact of nanotube morphology such as shell thicknesses, outer diameters, and surface properties on thermal transport. We also evaluate the frequency and mean-free-path spectra in these nanostructures to elucidate and provide insight on the phonon transport mechanisms in nanotubes. The results of this work advance the understanding of thermal conduction in nanotubes and the abilities to create rationally designed thermal materials, which are critical for obtaining high efficiency of thermoelectrics, photovoltaics, and electronic materials. (C) 2018 Elsevier Ltd. All rights reserved.