Two-Dimensional Phononic Crystals : Disorder Matters
Wagner, Markus R.. (Institut Català de Nanociència i Nanotecnologia)
Graczykowski, Bartlomiej (Institut Català de Nanociència i Nanotecnologia)
Reparaz, Juan Sebastian (Institut Català de Nanociència i Nanotecnologia)
Sachat, Alexandros el (Institut Català de Nanociència i Nanotecnologia)
Sledzinska, Marianna (Institut Català de Nanociència i Nanotecnologia)
Alzina, Francesc (Institut Català de Nanociència i Nanotecnologia)
Sotomayor Torres, Clivia M. (Institut Català de Nanociència i Nanotecnologia)

Date:	2016
Abstract:	The design and fabrication of phononic crystals (PnCs) hold the key to control the propagation of heat and sound at the nanoscale. However, there is a lack of experimental studies addressing the impact of order/disorder on the phononic properties of PnCs. Here, we present a comparative investigation of the influence of disorder on the hypersonic and thermal properties of two-dimensional PnCs. PnCs of ordered and disordered lattices are fabricated of circular holes with equal filling fractions in free-standing Si membranes. Ultrafast pump and probe spectroscopy (asynchronous optical sampling) and Raman thermometry based on a novel two-laser approach are used to study the phononic properties in the gigahertz (GHz) and terahertz (THz) regime, respectively. Finite element method simulations of the phonon dispersion relation and three-dimensional displacement fields furthermore enable the unique identification of the different hypersonic vibrations. The increase of surface roughness and the introduction of short-range disorder are shown to modify the phonon dispersion and phonon coherence in the hypersonic (GHz) range without affecting the room-temperature thermal conductivity. On the basis of these findings, we suggest a criteria for predicting phonon coherence as a function of roughness and disorder.
Grants:	European Commission 309150 European Commission 318352 European Commission 604668 Ministerio de Ciencia e Innovación CSD2010-0044 Ministerio de Ciencia e Innovación FIS2015-70862-P Ministerio de Economía y Competitividad SEV-2013-0295 European Commission 628197
Rights:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Phononic crystals ; Order ; Disorder ; Coherence ; Roughness ; Thermal conductivity
Published in:	Nano letters, Vol. 16, Issue 9 (September 2016) , p. 5661-5668, ISSN 1530-6992

DOI: 10.1021/acs.nanolett.6b02305

Postprint 20 p, 3.6 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles