Measurement of surface acoustic wave velocity using phase shift mask and application on thin film of thermoelectric material

ORAL

Abstract

We describe a convenient approach for measuring the velocity $v_{SAW}$ of surface acoustic waves (SAWs) of the near-surface layer of a material through optical pump-probe measurements and apply this method, in combination with conventional picosecond acoustics, to determine a subset of the elastic constants of thin films of semiconducting misfit layered compounds. SAWs with a wavelength of 700 nm are generated and detected using an elastomeric polydimethylsiloxane (PDMS) phase-shift mask which is fabricated using a commercially-available Si grating as a mold. The velocity of SAWs of [(SnSe)$_{1.04}$]$_{m}$[MoSe$_{2}$]$_{n}$ synthesized by elemental reactants show subtle variations in their elastic constants as a function of m and n. Precise measurements of elastic constants will enable a better understanding of interfacial stiffness in nanoscale multilayers and the effects of phonon focusing on thermal conductivity.

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Authors

  • Dongyao Li

    • Department of Materials Science and Engineering, Materials Research Laboratory, University of Illinois

  • Peng Zhao

    • Department of Material Science and Engineering, The Ohio State University

  • Noel Gunning

    • Department of Chemistry and Biochemistry, University of Oregon

  • David Johnson

    • Department of Chemistry and Biochemistry, University of Oregon

  • Ji-Cheng Zhao

    • Department of Material Science and Engineering, The Ohio State University

  • David Cahill

    • Department of Materials Science and Engineering, Materials Research Laboratory, University of Illinois