Landau damped collective excitations of the quasi-two-dimensional polaron gas in double heterostructures

Abstract

The spectrum of the collective and single-particle excitations of the quasi-two-dimensional polaron gas of a modulation doped GaAs-Ga 1- x Al x As double heterostructure is analyzed using the random-phase approximation for the electron gas. Caused by the plasmon-phonon coupling the long-wave optical phonons of the double heterostructure, the confined LO phonons and the interface phonons, become Landau damped in the regions of the single-particle intra- and intersubband continuum. Numerical results are presented for the dispersion curves and the energy-loss function. We have found additional non-phonon-like modes existing within the single-particle intra- and intersubband continuum.