Thermal conductivity of silicon nanomeshes: Effects of porosity and roughness

TL;DR

This study uses Monte Carlo simulations to analyze how porosity and surface roughness in silicon nanomeshes significantly reduce their thermal conductivity, with porosity having a stronger impact.

Contribution

It provides a theoretical analysis of how porosity and pore surface roughness influence thermal conductivity in silicon nanomeshes, highlighting the effects of pore arrangement.

Findings

50% porosity reduces thermal conductivity by about 80%

Surface roughness further decreases thermal conductivity, but less significantly

Pore arrangement along transport direction affects thermal transport

Abstract

We theoretically investigate thermal conductivity in silicon nanomeshes using Monte Carlo simulations of phonon transport. Silicon membranes of 100nm thickness with randomly located pores of 50nm diameter are considered. The effects of material porosity and pore surface roughness are examined. Nanomesh porosity is found to have a strong detrimental effect on thermal conductivity. At room temperature, a porosity of 50% results in ~80% reduction in thermal conductivity. Boundary roughness scattering further degrades thermal conductivity, but its effect is weaker. Thermal transport can additionally be affected by the specific arrangement of the pores along the transport direction.