Ab initio study of enhanced thermal conductivity in ordered AlGaO3 alloys

We compute the lattice thermal conductivity of monoclinic β-Ga2O3 and the ordered AlGaO3 alloy from the phonon Boltzmann transport equation, with the harmonic and third-order anharmonic force constants calculated from density functional theory. The calculated thermal conductivity of β-Ga2O3 is consistent with experiment. We demonstrate that the lowest-energy structure of an Al0.5Ga0.5 alloy, which is ordered, has a thermal conductivity that is raised by more than 70% compared to β-Ga2O3. We attribute the enhancement to (1) increased group velocities and (2) reduced anharmonic scattering rates due to the reduced weighted phase space. The findings offer an avenue toward improved heat dissipation from Ga2O3 devices.