Microscopic calculation of the electron-optical-phonon interaction in ultrathin GaAs/AlxGa1-xAs alloy quantum-well systems.

Abstract

We have calculated electron--optical-phonon scattering rates in ultrathin GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As alloy quantum-well systems of finite depth, based on a fully microscopic lattice dynamics approach for the phonon spectra. A pseudo-unit-cell model is utilized to calculate the lattice-dynamical properties of the ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As alloy system together with the two-parameter Keating potential and the long-range Coulomb potential between ions. The polar interactions of quantum confined electrons with GaAs- and AlAs-like optical modes are presented for both intrasubband and intersubband transitions, and the comparison with other theoretical calculations made. Good agreement is obtained for the 1\ensuremath{\rightarrow}1 and 2\ensuremath{\rightarrow}1 transition rates between the microscopic pseuso-unit-cell model and a macroscopic two-pole dielectric continuum model.