Anisotropic intrasubband hole scattering by polar optical phonon modes in thin GaAs/AlxGa1−xAs quantum wells

Abstract

A theoretical investigation of the hole – polar optical phonon scattering processes in thin GaAs/AlxGa1−xAs quantum wells is carried out at room temperature for both the confined and interface phonon modes within the dielectric continuum model framework. For high accuracy, the model for the hole dispersion uses the 6×6 Luttinger–Kohn Hamiltonian. Detailed and extensive calculations based on this model show that the rates for intra-subband scattering processes differ significantly from those of bulk GaAs because of quantization and reduced dimensionality. Moreover, the study of scattering as a function of hole energy shows that the trend of the scattering rates is governed mostly by (i) overlap integrals and (ii) the density of the final states to which the hole scatters. The influence of warping, in the hole energy dispersion, on the phonon scattering rates is also explored and found to be important when the initial hole energy is high. Our calculations show evidence of strong anisotropy in the scattering rates especially for processes involving the heavy hole subband, which anisotropy is in fact quite important and far from being negligible.