https://doi.org/10.1140/epjp/s13360-023-04659-x
Regular Article
Thermal transport in H-terminated ultrathin [110] Si nanowires: a first principles study
1
Department of Physics, University of Cagliari, Cittadella Universitaria, 09042, Monserrato, CA, Italy
2
CNRS, Institut de Minéralogie, de Physiques des Matériaux et de Cosmochimie, IMPMC, Sorbonne Unversité, UMR 7590, 4 Place Jussieu, 75252, Paris Cedex 05, France
Received:
26
April
2023
Accepted:
2
November
2023
Published online:
20
November
2023
Phonon properties of ultrathin Si nanowires in [110] direction have been calculated by density functional perturbation theory. Several samples with varying diameters ranging from 0.38 to 1.5 nm have been investigated. It is found that the frequencies of optical phonons at the zone center increase with decrease in size of the nanowire, giving rise to avoided-crossing with longitudinal acoustic phonons. This feature determines a corresponding increase in the scattering rates and flattening of the longitudinal acoustic mode. More specifically, a remarkable change in scattering rates is shown for decreasing diameter. Results of the thermal conductivity are much lower with respect to bulk Si and are found between 40 and 119 
, also providing evidence of increasing thermal conductivity with increase in diameter. This effect is attributed to several changes in the phonon dispersions. Finally, it is shown that approximating the boundary scattering of phonons by Casimir scattering leads to a severe underestimation of the thermal conductivity in these systems.
© The Author(s) 2023
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
