Phonon thermal transport properties of GaN with symmetry-breaking and lattice deformation induced by the 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 in the finite electric field are investigated using first-principles calculations from the perspectives of symmetry-breaking and lattice deformation. Effects of electric field on phonon transport properties including phonon dispersion and thermal conductivity from the 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 the symmetry of zincblende lattice. While the latter affects both lattice symmetry and size, causing significant changes in phonon properties and an increase in thermal conductivity. In wurtzite GaN, space-group-conserved lattice changes in the finite electric field are studied with lattice deformation only, where thermal conductivity decreases at electric fields significantly with the increase of anisotropy, much different from the changes in zincblende GaN. This work provides a comprehensive understanding of phonon thermal transport properties in GaN in the finite electric field, which promises to benefit phonon transport tuning and provide a reference for thermal management in GaN-based information and power electronics.