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

Fariborz Kargar, Bishwajit Debnath, Joona Pekko Kakko, Antti Säynätjoki, Harri Lipsanen, Denis L. Nika, Roger K. Lake, Alexander A. Balandin*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

40 Citations (Scopus)
121 Downloads (Pure)

Abstract

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.

Original languageEnglish
Article number13400
Number of pages7
JournalNature Communications
Volume7
DOIs
Publication statusPublished - 10 Nov 2016
MoE publication typeA1 Journal article-refereed

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