title: Thermal conductivity and large isotope effect in GaN from first principles.
abstract: We present atomistic first principles results for the lattice thermal conductivity of GaN and compare them to those for GaP, GaAs, and GaSb. In GaN we find a large increase to the thermal conductivity with isotopic enrichment, ~65% at room temperature. We show that both the high thermal conductivity and its enhancement with isotopic enrichment in GaN arise from the weak coupling of heat-carrying acoustic phonons with optic phonons. This weak scattering results from stiff atomic bonds and the large Ga to N mass ratio, which give phonons high frequencies and also a pronounced energy gap between acoustic and optic phonons compared to other materials. Rigorous understanding of these features in GaN gives important insights into the interplay between intrinsic phonon-phonon scattering and isotopic scattering in a range of materials.
authors.affiliation: Naval Research Laboratory, Washington, DC 20375, USA.
authors.forename: L
authors.initials: L
authors.lastname: Lindsay
authors.forename: D A
authors.initials: DA
authors.lastname: Broido
authors.forename: T L
authors.initials: TL
authors.lastname: Reinecke