Phonon thermal transport properties of GaN with symmetry-breaking and lattice deformation induced by the electric field

TL;DR

This study investigates how electric fields influence phonon transport in GaN with different crystal structures, revealing symmetry-breaking effects and lattice deformations that significantly alter thermal conductivity, aiding thermal management in electronics.

Contribution

It provides a comprehensive first-principles analysis of electric field effects on phonon properties in GaN's wurtzite and zincblende structures, highlighting symmetry-breaking and lattice deformation impacts.

Findings

Electric field causes phonon branch splitting in zincblende GaN.

Lattice deformation increases thermal conductivity in zincblende GaN.

Thermal conductivity decreases and becomes more anisotropic in wurtzite GaN under electric field.

Abstract

Electric fields commonly exist in semiconductor structures of electronics, bringing to bear on phonon thermal transport. Also, it is a popular method to tune thermal transport in solids. In this work, phonon and thermal transport properties of GaN with wurtzite and zincblende structures at finite electric field are investigated using first principles calculations from perspectives of symmetry breaking and lattice deformation. Effects of electric field on phonon transport properties including phonon dispersion and thermal conductivity from response of electron density distribution only and response from lattice changes are studied in zincblende GaN. It is found that the former has a small but qualitative impact on phonon dispersion relations, i.e., splitting of phonon branches, since it breaks symmetry of zincblende lattice. While the latter affects both lattice symmetry and size, causing significant changes of phonon properties and increase of thermal conductivity. In wurtzite GaN, space-group-conserved lattice changes at finite electric field are studied with lattice deformation only, where thermal conductivity decreases at electric fields significantly with increase of anisotropy, much different from the changes in zincblende GaN. This work provides a comprehensive understanding on phonon thermal transport properties in GaN at finite electric field, which promises to benefit phonon transport tuning and provide reference for thermal management in GaN-based information and power electronics.