Thermal Properties of Nanocrystalline Silicon Nanobeams

Jeremie Maire (Corresponding Author), Emigdio Chávez-Ángel, Guillermo Arregui, Martin F. Colombano, Nestor E. Capuj, Amadeu Griol, Alejandro Martínez, Daniel Navarro-Urrios, Jouni Ahopelto, Clivia M. Sotomayor-Torres

    Research output: Contribution to journalArticleScientificpeer-review

    6 Citations (Scopus)


    Controlling thermal energy transfer at the nanoscale and thermal properties has become critically important in many applications since it often limits device performance. In this study, the effects on thermal conductivity arising from the nanoscale structure of free-standing nanocrystalline silicon films and the increasing surface-to-volume ratio when fabricated into suspended optomechanical nanobeams are studied. Thermal transport and elucidate the relative impact of different grain size distributions and geometrical dimensions on thermal conductivity are characterized. A micro time-domain thermoreflectance method to study free-standing nanocrystalline silicon films and find a drastic reduction in the thermal conductivity, down to values below 10 W m–1 K–1 is used, with a stronger decrease for smaller grains. In optomechanical nanostructures, this effect is smaller than in membranes due to the competition of surface scattering in decreasing thermal conductivity. Finally, a novel versatile contactless characterization technique that can be adapted to any structure supporting a thermally shifted optical resonance is introduced. The thermal conductivity data agrees quantitatively with the thermoreflectance measurements. This study opens the way to a more generalized thermal characterization of optomechanical cavities and to create hot-spots with engineered shapes at the desired position in the structures as a means to study thermal transport in coupled photon-phonon structures.

    Original languageEnglish
    Article number2105767
    Number of pages10
    JournalAdvanced Functional Materials
    Issue number4
    Early online date23 Oct 2021
    Publication statusPublished - 19 Jan 2022
    MoE publication typeA1 Journal article-refereed


    This work was supported by the European Commission FET Open project PHENOMEN (G.A. Nr. 713450). ICN2 was supported by the S. Ochoa program from the Spanish Research Agency (AEI, grant no. SEV‐2017‐0706) and by the CERCA Programme / Generalitat de Catalunya. ICN2 authors acknowledge the support from the Spanish MICINN project SIP (PGC2018‐101743‐B‐I00). D.N.U. and M.F.C. acknowledge the support of a Ramón y Cajal postdoctoral fellowship (RYC‐2014‐15392) and a Severo Ochoa studentship, respectively. E.C.A. acknowledges financial support from the EU FET Open Project NANOPOLY. (GA 829061). A.M. acknowledges support from Ministerio de Ciencia, Innovación y Universidades (grant PGC2018‐094490‐B, PRX18/00126) and Generalitat Valenciana (grants PROMETEO/2019/123, and IDIFEDER/2018/033).


    • nanostructured materials
    • optomechanics
    • phonons
    • polycrystalline
    • silicon
    • thermal characterization methods
    • thermal conduction


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