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

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 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 uniform silicon membrane. We show that while the phonon-vibron DOS conformity 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.

References in corpus (13)

• Phononics: Manipulating heat flow with electronic analogs and beyond
• Minimum Thermal Conductivity of Superlattices
• Nanophononic metamaterial: Thermal conductivity reduction by local resonance
• Extreme Low Thermal Conductivity in Nanoscale 3D Si Phononic Crystal with Spherical Pores
• Ab initio optimization of phonon drag effect for lower-temperature thermoelectric energy conversion
• Towards More Accurate Molecular Dynamics Calculation of Thermal Conductivity. Case Study: GaN Bulk Crystals
• Coherent and Incoherent Thermal Transport in Nanomeshes
• Unexpected Thermal Conductivity Enhancement in Pillared Graphene Nanoribbon with Isotopic Resonance
• Phonon Band Structure and Thermal Transport Correlation in a Layered Diatomic Crystal
• Spectral energy analysis of locally resonant nanophononic metamaterials by molecular simulations
• Two orders of magnitude reduction in silicon membrane thermal conductivity by resonance hybridizations
• Thermal transport size effects in silicon membranes featuring nanopillars as local resonators
• Semiconductor thermal and electrical properties decoupled by localized phonon resonances