Monte Carlo Study of Temperature-dependent Non-diffusive Thermal Transport in Si Nanowires

TL;DR

This study uses advanced Monte Carlo simulations of the phonon Boltzmann transport equation to analyze how boundary scattering and nanowire length influence non-diffusive thermal transport in silicon nanowires across various temperatures.

Contribution

It provides a comprehensive, parameter-free analysis of non-diffusive thermal transport in silicon nanowires using first-principles data and a variance reduced Monte Carlo approach.

Findings

Nanowire length significantly affects thermal conductivity.

Phonon confinement effects are substantial in silicon nanowires.

Temperature influences the degree of non-diffusive transport.

Abstract

Non-diffusive thermal transport has gained extensive research interest recently due to its important implications on fundamental understanding of material phonon mean free path distributions and many nanoscale energy applications. In this work, we systematically investigate the role of boundary scattering and nanowire length on the nondiffusive thermal transport in thin silicon nanowires by rigorously solving the phonon Boltzmann transport equation using a variance reduced Monte Carlo technique across a range of temperatures. The simulations use the complete phonon dispersion and spectral lifetime data obtained from first-principle density function theory calculations as input without any adjustable parameters. Our BTE simulation results show that the nanowire length plays an important role in determining the thermal conductivity of silicon nanowires. In addition, our simulation results suggest significant phonon confinement effect for the previously measured silicon nanowires. These findings are important for a comprehensive understanding of microscopic non-diffusive thermal transport in silicon nanowires.