Lifetime of high-order thickness resonances of thin silicon membranes

A. A. Maznev, F. Hofmann, J. Cuffe, J. K. Eliason, K. A. Nelson

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Femtosecond laser pulses are used to excite and probe high-order longitudinal thickness resonances at a frequency of ∼270 GHz in suspended Si membranes with thickness ranging from 0.4 to 15 μm. The measured acoustic lifetime scales linearly with the membrane thickness and is shown to be controlled by the surface specularity which correlates with roughness characterized by atomic force microscopy. Observed Q-factor values up to 2400 at room temperature result from the existence of a local maximum of the material Q in the sub-THz range. However, surface specularity would need to be improved over measured values of ∼0.5 in order to achieve high Q values in nanoscale devices. The results support the validity of the diffuse boundary scattering model in analyzing thermal transport in thin Si membranes.

Original languageEnglish (US)
Pages (from-to)116-121
Number of pages6
StatePublished - Feb 1 2015
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported as part of the S3TEC Energy Frontier Research Center funded by the US. Department of Energy, Office of Basic Energy Sciences under Award No. DE-SC0001299/DE-FG02-09ER46577 . The authors would like to thank Clivia M. Sotomayor and Gang Chen for stimulating discussions. C.M. Sotomayor and Timothy Kehoe are also thanked for their help in fabricating the in-house samples, which were fabricated at the Catalan Institute for Nanoscience and Nanotechnology using facilities of the ICTS ‘‘Integrated Nano and Microfabrication Clean Room’’ (CSIC-CNM).

Publisher Copyright:
© 2014 Elsevier B.V. All rights reserved.


  • Phonon lifetime
  • Q-factor
  • Silicon membranes
  • Surface specularity
  • Thickness resonances


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