Band dispersion, scattering rate, and carrier mobility using the poles of Green’s function for dilute nitride alloys

Abstract

The band-anticrossing (BAC) model provides the basis for the self-consistent Green’s function method that we have previously developed to calculate the density of states of GaNxAs1−x dilute nitride alloys. In this paper, we extend this Green’s function method to include the complex energy states and to find the poles of the Green’s function, thereby allowing one to calculate the dispersion relation, group velocity, and the carrier decay rate in disordered dilute nitride alloys. Two different models of the N states have been studied to investigate the band structure of these materials: (1) the conventional two-band BAC model, which assumes that all N states are located at the same energy, and (2) a model which includes N states distributed over a range of energies, as expected in actual dilute nitride samples. Our results for the second model show a much shorter carrier mean-free path, and lower carrier mobility for GaNxAs1−x, with the magnitude of the calculated mobility in good agreement with the experimental data.