Ab initio study of lattice vibration and polaron properties in zinc-blende Al_xGa_(1-x)N alloys

摘要

We report on first-principles studies to investigate the zone-centre optical phonons and polaron properties in zinc-blende Al_xGa_(1-x)N alloys over the whole compositional range. The calculations are performed using ab initio pseudopotential approach based on the density functional perturbation theory under the virtual crystal approximation. Features such as phonon frequencies, dielectric constants, Frohlich coupling constant, Debye temperature, effective polar field, deformation potential, and polaron effective mass have been determined. Reasonable agreement is obtained between our computed values and data available in the literature. Other case, our results are predictions. The phonon modes are broadened upon alloying and their frequencies display a blueshift with increasing Al content. The dependence of the studied parameters on Al concentration is found to be monotonic.