title: Thermal diffuse scattering as a probe of large-wave-vector phonons in silicon nanostructures.
abstract: Large-wave-vector phonons have an important role in determining the thermal and electronic properties of nanoscale materials. The small volumes of such structures, however, have posed significant challenges to experimental studies of the phonon dispersion. We show that synchrotron x-ray thermal diffuse scattering can be adapted to probe phonons with wave vectors spanning the entire Brillouin zone of nanoscale silicon membranes. The thermal diffuse scattering signal from flat Si nanomembranes with thicknesses from 315 to 6 nm, and a sample volume as small as 5 μm(3), has the expected linear dependence on the membrane thickness and also exhibits excess intensity at large wave vectors, consistent with the scattering signature expected from low-lying large-wave-vector modes of the membranes.
authors.affiliation: Materials Science and Engineering and Materials Science Program, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Gokul
authors.initials: G
authors.lastname: Gopalakrishnan
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Martin V
authors.initials: MV
authors.lastname: Holt
authors.affiliation: Materials Science and Engineering and Materials Science Program, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Kyle M
authors.initials: KM
authors.lastname: McElhinny
authors.affiliation: Materials Science and Engineering and Materials Science Program, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Josef W
authors.initials: JW
authors.lastname: Spalenka
authors.affiliation: Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Czaplewski
authors.affiliation: European Synchrotron Radiation Facility, F-38043 Grenoble, France.
authors.forename: Tobias U
authors.initials: TU
authors.lastname: Schülli
authors.affiliation: Materials Science and Engineering and Materials Science Program, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Evans