Vibronics of multi-material nanopillared membranes and impact on the thermal conductivity

Lina Yang, Mahmoud I. Hussein

Research output: Contribution to journalArticlepeer-review

Abstract

Atomic motion in nanopillars standing on the surface of a silicon membrane generates vibrons, which are wavenumber-independent phonons that act as local resonances. These vibrons couple with the vast majority of the phonon population, including heat-carrying phonons, traveling along the base membrane causing a reduction in the in-plane lattice thermal conductivity. In this work, we examine isolated silicon and gallium nitride nanopillars and for each compare the vibrons density of states (DOS) to those of phonons in an isolated version of the silicon membrane. We show that while the conformity of the phonon-vibron DOS distribution between the two components across the full spectrum is a key factor in reducing the thermal conductivity of the assembled nanostructure, the presence of an intense vibron population at more dominant low frequencies plays a competing role. We report predictions from molecular dynamics simulations showing lower thermal conductivities for a silicon membrane with gallium-nitride nanopillars compared to a silicon membrane with silicon nanopillars.

Original languageEnglish
JournalJournal of Physics Condensed Matter
Volume36
Issue number50
DOIs
Publication statusPublished - 24 Sept 2024

Keywords

  • molecular simulations
  • nanophononic metamaterial
  • phononics
  • silicon membranes
  • thermal transport
  • vibronics

Cite this