Phonons in slow motion: Dispersion relations in ultrathin Si membranes

  • John Cuffe
  • , Emigdio Chávez
  • , Andrey Shchepetov
  • , Pierre-Olivier Chapuis
  • , El Houssaine El Boudouti
  • , Francesc Alzina
  • , Timothy Kehoe
  • , Jordi Gomis-Bresco
  • , Damian Dudek
  • , Yan Pennec
  • , Bahram Djafari-Rouhani
  • , Mika Prunnila
  • , Jouni Ahopelto
  • , Clivia M. Sotomayor Torres*
  • *Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    86 Citations (Scopus)

    Abstract

    We report the changes in dispersion relations of hypersonic acoustic phonons in free-standing silicon membranes as thin as ∼8 nm. We observe a reduction of the phase and group velocities of the fundamental flexural mode by more than 1 order of magnitude compared to bulk values. The modification of the dispersion relation in nanostructures has important consequences for noise control in nano- and microelectromechanical systems (MEMS/NEMS) as well as opto-mechanical devices.
    Original languageEnglish
    Pages (from-to)3569-3573
    JournalNano Letters
    Volume12
    Issue number7
    DOIs
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Confined phonons
    • dispersion relations
    • inelastic light scattering
    • Si membranes
    • slow phonons
    • ultrathin

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