A Universal Gauge for Thermal Conductivity of Silicon Nanowires With Different Cross Sectional Geometries

TL;DR

This study uses molecular dynamics to establish a universal linear relationship between surface-to-volume ratio and thermal conductivity in silicon nanowires, aiding in their design for thermal management.

Contribution

It introduces a universal linear dependence of thermal conductivity on surface-to-volume ratio across different silicon nanowire geometries, regardless of shape.

Findings

Thermal conductivity decreases with increasing surface-to-volume ratio.

A universal linear relationship exists between thermal conductivity and SVR for SiNWs larger than 20 nm^2.

Triangular cross-section SiNWs have the lowest thermal conductivity among shapes with the same area.

Abstract

By using molecular dynamics simulations, we study thermal conductivity of silicon nanowires (SiNWs) with different cross sectional geometries. It is found that thermal conductivity decreases monotonically with the increase of surface-to-volume ratio (SVR). More interestingly, a simple universal linear dependence of thermal conductivity on SVR is observed for SiNWs with modest cross sectional area (larger than 20 nm^2), regardless of the cross sectional geometry. As a result, among different shaped SiNWs with the same cross sectional area, the one with triangular cross section has the lowest thermal conductivity. Our study provides not only a universal gauge for thermal conductivity among different cross sectional geometries, but also a designing guidance to tune thermal conductivity by geometry.