Thermal conductivity reduction by 60{\deg} shuffle-set dislocation arrays embedded in silicon nano-films

TL;DR

This paper investigates how embedding dense 60-degree shuffle-set dislocation arrays in silicon nano-films drastically reduces thermal conductivity, primarily through phonon scattering at dislocation cores, achieving a reduction to 2% of bulk silicon.

Contribution

It introduces a combined theoretical and simulation approach to quantify the impact of dislocation arrays on silicon's thermal conductivity, revealing a significant reduction mechanism.

Findings

Thermal conductivity reduced to 2% of bulk silicon.

Dislocation density above 10^14 m^-2 causes significant reduction.

Phonon scattering at dislocation cores is the main mechanism.

Abstract

Based on the Debye-Callaway and the Klemens model, as well as molecular dynamics, the paper proposes mechanism of thermal conductivity reduction by embedding dense 60{\deg} shuffle-set dislocation arrays into silicon nano-films. Thermal conductivity reduction to 2% of that of bulk silicon has been obtained. The reduction is found mainly due to longitudinal phonon scattering at the dislocation cores, where the scattering rate is stronger than that presented by Klemens. Within an effective diameter of about 9 nm around their cores, the dislocations locally scatter phonons, resulting in a dramatical density-dependent reduction of thermal conductivity for a dislocation density larger than 10^14 m^-2.