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Direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires

Similar to electron waves, the phonon states in semiconductors can undergo changes induced by external boundaries. However, despite strong scientific and practical importance, conclusive experimental evidence of confined acoustic phonon polarization branches in individual free-standing nanostructure...

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Autores principales: Kargar, Fariborz, Debnath, Bishwajit, Kakko, Joona-Pekko, Säynätjoki, Antti, Lipsanen, Harri, Nika, Denis L., Lake, Roger K., Balandin, Alexander A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5109588/
https://www.ncbi.nlm.nih.gov/pubmed/27830698
http://dx.doi.org/10.1038/ncomms13400
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author Kargar, Fariborz
Debnath, Bishwajit
Kakko, Joona-Pekko
Säynätjoki, Antti
Lipsanen, Harri
Nika, Denis L.
Lake, Roger K.
Balandin, Alexander A.
author_facet Kargar, Fariborz
Debnath, Bishwajit
Kakko, Joona-Pekko
Säynätjoki, Antti
Lipsanen, Harri
Nika, Denis L.
Lake, Roger K.
Balandin, Alexander A.
author_sort Kargar, Fariborz
collection PubMed
description Similar to electron waves, the phonon states in semiconductors can undergo changes induced by external boundaries. However, despite strong scientific and practical importance, conclusive experimental evidence of confined acoustic phonon polarization branches in individual free-standing nanostructures is lacking. Here we report results of Brillouin—Mandelstam light scattering spectroscopy, which reveal multiple (up to ten) confined acoustic phonon polarization branches in GaAs nanowires with a diameter as large as 128 nm, at a length scale that exceeds the grey phonon mean-free path in this material by almost an order-of-magnitude. The dispersion modification and energy scaling with diameter in individual nanowires are in excellent agreement with theory. The phonon confinement effects result in a decrease in the phonon group velocity along the nanowire axis and changes in the phonon density of states. The obtained results can lead to more efficient nanoscale control of acoustic phonons, with benefits for nanoelectronic, thermoelectric and spintronic devices.
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spelling pubmed-51095882017-01-13 Direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires Kargar, Fariborz Debnath, Bishwajit Kakko, Joona-Pekko Säynätjoki, Antti Lipsanen, Harri Nika, Denis L. Lake, Roger K. Balandin, Alexander A. Nat Commun Article Similar to electron waves, the phonon states in semiconductors can undergo changes induced by external boundaries. However, despite strong scientific and practical importance, conclusive experimental evidence of confined acoustic phonon polarization branches in individual free-standing nanostructures is lacking. Here we report results of Brillouin—Mandelstam light scattering spectroscopy, which reveal multiple (up to ten) confined acoustic phonon polarization branches in GaAs nanowires with a diameter as large as 128 nm, at a length scale that exceeds the grey phonon mean-free path in this material by almost an order-of-magnitude. The dispersion modification and energy scaling with diameter in individual nanowires are in excellent agreement with theory. The phonon confinement effects result in a decrease in the phonon group velocity along the nanowire axis and changes in the phonon density of states. The obtained results can lead to more efficient nanoscale control of acoustic phonons, with benefits for nanoelectronic, thermoelectric and spintronic devices. Nature Publishing Group 2016-11-10 /pmc/articles/PMC5109588/ /pubmed/27830698 http://dx.doi.org/10.1038/ncomms13400 Text en Copyright © 2016, The Author(s) http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Kargar, Fariborz
Debnath, Bishwajit
Kakko, Joona-Pekko
Säynätjoki, Antti
Lipsanen, Harri
Nika, Denis L.
Lake, Roger K.
Balandin, Alexander A.
Direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires
title Direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires
title_full Direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires
title_fullStr Direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires
title_full_unstemmed Direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires
title_short Direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires
title_sort direct observation of confined acoustic phonon polarization branches in free-standing semiconductor nanowires
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5109588/
https://www.ncbi.nlm.nih.gov/pubmed/27830698
http://dx.doi.org/10.1038/ncomms13400
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