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Title: Synchrotron x-ray thermal diffuse scattering probes for phonons in Si/SiGe/Si trilayer nanomembranes

Nanostructures offer the opportunity to control the vibrational properties of via the scattering of phonons due to boundaries and mass disorder as well as through changes in the phonon dispersion due to spatial confinement. Advances in understanding these effects have the potential to lead to thermoelectrics with an improved figure of merit by lowering the thermal conductivity and to provide insight into electron-phonon scattering rates in nanoelectronics. However, characterizing the phonon population in nanomaterials has been challenging because of their small volume and because optical techniques probe only a small fraction of reciprocal space. Recent developments in x-ray scattering now allow the phonon population to be evaluated across all of reciprocal space in samples with volumes as small as several cubic micrometers. We apply this approach, synchrotron x-ray thermal diffuse scattering (TDS), to probe the population of phonons within a Si/SiGe/Si trilayer nanomembrane. The distributions of scattered intensity from Si/SiGe/Si trilayer nanomembranes and Si nanomembranes with uniform composition are qualitatively similar, with features arising from the elastic anisotropy of the diamond structure. The TDS signal for the Si/SiGe/Si nanomembrane, however, has higher intensity than the Si membrane of the same total thickness by approximately 3.75%. Possible origins of the enhancementmore » in scattering from SiGe in comparison with Si include the larger atomic scattering factor of Ge atoms within the SiGe layer or reduced phonon frequencies due to alloying.« less
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [3] ;  [1]
  1. Univ. of Wisconsin, Madison, WI (United States). Materials Science and Engineering
  2. Univ. of Wisconsin, Madison, WI (United States). Materials Science and Engineering; Univ. of Wisconsin, Platteville, WI (United States). Engineering Physics
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials
Publication Date:
Grant/Contract Number:
FG02-04ER46147; FA9550-10-1-0249; 1121288; AC02-06CH11357; FG02‐03ER46028
Accepted Manuscript
Journal Name:
MRS Advances
Additional Journal Information:
Journal Volume: 1; Journal Issue: 48; Journal ID: ISSN 2059-8521
Materials Research Society (MRS)
Research Org:
Univ. of Wisconsin-Madison, Madison, WI (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; US Air Force Office of Scientific Research (AFOSR); 3M Science and Technology Fellowship Program.
Contributing Orgs:
Center for Nanoscale Materials, Argonne National Laboratory
Country of Publication:
United States
36 MATERIALS SCIENCE; Semiconductor nanomaterials; vibrational and thermal properties of nanomaterials; x-ray diffuse scattering; nanostructure; x-ray diffraction (XRD); thermal conductivity
OSTI Identifier: