Phononic thermal resistance due to a finite periodic array of nano-scatterers

TL;DR

This paper investigates how a finite periodic array of nano-scatterers affects phononic thermal transport, revealing that such arrays can serve as effective thermal barriers with temperature-dependent conductance.

Contribution

It introduces a wave-based analysis of phonon transmission through nano-scatterer arrays, including roughness effects and polarization conversion, providing new insights into phononic thermal resistance.

Findings

Arrays act as efficient thermal barriers.

Thermal conductance shows temperature dependence similar to non-filtered cases.

Diffraction and polarization effects influence phonon transmission.

Abstract

The wave property of phonons is employed to explore the thermal transport across a finite periodic array of nano-scatterers such as circular and triangular holes. As thermal phonons are generated in all directions, we study their transmission through a single array for both normal and oblique incidences, using a linear dispersionless time-dependent acoustic frame in a two-dimensional system. Roughness effects can be directly considered within the computations without relying on approximate analytical formulae. Analysis by spatio-temporal Fourier transform allows us to observe the diffraction effects and the conversion of polarization. Frequency-dependent energy transmission coefficients are computed for symmetric and asymmetric objects. We demonstrate that the phononic array acts as an efficient thermal barrier by applying the theory of thermal boundary (Kapitza) resistances to arrays of smooth scattering holes in silicon for an exemplifying periodicity of 10 nm in the [5-100 K] temperature range. It is observed that the associated thermal conductance has the same temperature dependence than that without phononic filtering.