title: Nanomechanical probing of the layer/substrate interface of an exfoliated InSe sheet on sapphire.
abstract: Van der Waals (vdW) layered crystals and heterostructures have attracted substantial interest for potential applications in a wide range of emerging technologies. An important, but often overlooked, consideration in the development of implementable devices is phonon transport through the structure interfaces. Here we report on the interface properties of exfoliated InSe on a sapphire substrate. We use a picosecond acoustic technique to probe the phonon resonances in the InSe vdW layered crystal. Analysis of the nanomechanics indicates that the InSe is mechanically decoupled from the substrate and thus presents an elastically imperfect interface. A high degree of phonon isolation at the interface points toward applications in thermoelectric devices, or the inclusion of an acoustic transition layer in device design. These findings demonstrate basic properties of layered structures and so illustrate the usefulness of nanomechanical probing in nanolayer/nanolayer or nanolayer/substrate interface tuning in vdW heterostructures.
authors.affiliation: School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Ryan
authors.initials: R
authors.lastname: Beardsley
authors.affiliation: School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Akimov
authors.affiliation: School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Jake D G
authors.initials: JD
authors.lastname: Greener
authors.affiliation: School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Garry W
authors.initials: GW
authors.lastname: Mudd
authors.affiliation: School of Physics, Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), CET campus, Engineering College PO, Thiruvananthapuram, Kerala, India.
authors.forename: Sathyan
authors.initials: S
authors.lastname: Sandeep
authors.affiliation: School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Zakhar R
authors.initials: ZR
authors.lastname: Kudrynskyi
authors.affiliation: Frantsevich Institute for Problems of Materials Science, The National Academy of Sciences of Ukraine, Chernivtsi Branch, Chernivtsi 58001, Ukraine.
authors.forename: Zakhar D
authors.initials: ZD
authors.lastname: Kovalyuk
authors.affiliation: School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Amalia
authors.initials: A
authors.lastname: Patanè
authors.affiliation: School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Kent