Phonons in Slow Motion: Dispersion Relations in Ultra-Thin Si Membranes

Abstract

We report the changes in dispersion relations of hypersonic acoustic phonons in free-standing silicon membranes as thin as \sim 8 nm. We observe a reduction of the phase and group velocities of the fundamental flexural mode by more than one order of magnitude compared to bulk values. The modification of the dispersion relation in nanostructures has important consequences for noise control in nano and micro-electromechanical systems (MEMS/NEMS) as well as opto-mechanical devices.

5 pages

References in corpus (4)

• Energy Dissipation and Transport in Nanoscale Devices
• Optomechanical Crystals
• An Atomic-resolution nanomechanical mass sensor
• Confinement of acoustical vibrations in a semiconductor planar phonon cavity

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