Thermal transport size effects in silicon membranes featuring nanopillars as local resonators

TL;DR

This study uses molecular simulations to analyze how nanopillar size, unit-cell size, and sample size influence thermal conductivity reduction in silicon membranes with surface nanopillars acting as local resonators.

Contribution

It provides new insights into the size-dependent effects of nanopillars on thermal transport in silicon membranes, highlighting the role of resonance hybridization.

Findings

Thermal conductivity reduction increases with the volumetric size ratio of nanopillars to membrane.

The reduction varies with unit-cell size depending on the volumetric ratio.

Resonance-induced thermal conductivity drop slightly increases with the number of unit cells, then levels off.

Abstract

Silicon membranes patterned by nanometer-scale pillars standing on the surface provide a practical platform for thermal conductivity reduction by resonance hybridization. Using molecular simulations, we investigate the effect of nanopillar size, unit-cell size, and finite-structure size on the net capacity of the local resonators in reducing the thermal conductivity of the base membrane. The results indicate that the thermal conductivity reduction increases as the ratio of the volumetric size of a unit nanopillar to that of the base membrane is increased, and the intensity of this reduction varies with unit-cell size at a rate dependent on the volumetric ratio. Considering sample size, the resonance-induced thermal conductivity drop is shown to increase slightly with the number of unit cells until it would eventually level off.