Gallium Arsenide Thermal Conductivity and Optical Phonon Relaxation Times from First-Principles Calculations

TL;DR

This study uses first-principles calculations to accurately determine GaAs's thermal conductivity, phonon relaxation times, and size effects, providing insights relevant for nanoscale device applications.

Contribution

It introduces a first-principles approach to compute GaAs thermal properties, including optical phonon relaxation times and size-dependent effects, with good agreement to experimental data.

Findings

Calculated thermal conductivity matches experimental data

Size effects significantly influence nanoscale GaAs thermal conductivity

Optical phonon relaxation times and scattering channels are characterized

Abstract

In this paper, thermal conductivity of crystalline GaAs is calculated using first-principles lattice dynamics. The harmonic and cubic force constants are obtained by fitting them to the force-displacement data from density functional theory calculations. Phonon dispersion is calculated from dynamical matrix constructed using the harmonic force constants and phonon relaxation times are calculated using Fermi Golden rule. The calculated GaAs thermal conductivity agrees well with experimental data. Thermal conductivity accumulations as a function of phonon mean free path and as a function of wavelength are obtained. Our results predict significant size effect on the GaAs thermal conductivity in the nanoscale. Relaxation times of optical phonons and their contributions from different scattering channels are also studied. Such information will help understanding hot phonon effects in GaAs-based devices.