Thermal conductivity of silicon nanomeshes: Effects of porosity and roughness

We theoretically investigate thermal conductivity in silicon nanomeshes using Monte Carlo simulations of phonon transport. Silicon membranes of 100 nm thickness with randomly located pores of 50 nm 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.