title: Tuning thermal transport in ultrathin silicon membranes by surface nanoscale engineering.
abstract: A detailed understanding of the connections of fabrication and processing to structural and thermal properties of low-dimensional nanostructures is essential to design materials and devices for phononics, nanoscale thermal management, and thermoelectric applications. Silicon provides an ideal platform to study the relations between structure and heat transport since its thermal conductivity can be tuned over 2 orders of magnitude by nanostructuring. Combining realistic atomistic modeling and experiments, we unravel the origin of the thermal conductivity reduction in ultrathin suspended silicon membranes, down to a thickness of 4 nm. Heat transport is mostly controlled by surface scattering: rough layers of native oxide at surfaces limit the mean free path of thermal phonons below 100 nm. Removing the oxide layers by chemical processing allows us to tune the thermal conductivity over 1 order of magnitude. Our results guide materials design for future phononic applications, setting the length scale at which nanostructuring affects thermal phonons most effectively.
authors.affiliation: †Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Sanghamitra
authors.initials: S
authors.lastname: Neogi
authors.affiliation: ‡ICN2, Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: J Sebastian
authors.initials: JS
authors.lastname: Reparaz
authors.affiliation: §Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59078-900, Brazil.
authors.forename: Luiz Felipe C
authors.initials: LF
authors.lastname: Pereira
authors.affiliation: ‡ICN2, Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Bartlomiej
authors.initials: B
authors.lastname: Graczykowski
authors.affiliation: ‡ICN2, Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Markus R
authors.initials: MR
authors.lastname: Wagner
authors.affiliation: ‡ICN2, Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Marianna
authors.initials: M
authors.lastname: Sledzinska
authors.affiliation: ⊥VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Espoo, Finland.
authors.forename: Andrey
authors.initials: A
authors.lastname: Shchepetov
authors.affiliation: ⊥VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Espoo, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Prunnila
authors.affiliation: ⊥VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Espoo, Finland.
authors.forename: Jouni
authors.initials: J
authors.lastname: Ahopelto
authors.affiliation: ‡ICN2, Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, 08193 Bellaterra, Barcelona, Spain.|∥ICREA, Catalan Institute for Research and Advanced Studies, 08010 Barcelona, Spain.
authors.forename: Clivia M
authors.initials: CM
authors.lastname: Sotomayor-Torres
authors.affiliation: †Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Davide
authors.initials: D
authors.lastname: Donadio
keywords: Si membranes; classical molecular dynamics; dispersion relations; inelastic light scattering; lattice thermal transport; phonon engineering; quasi-2D system; two-laser Raman thermometry