Phonons in GaAs/AlAs superlattices

Abstract

Phonon modes in GaAs/AlAs superlattices have been calculated in a valence-force-field model characterized by bond-stretching and -bending forces and a fixed effective charge. They have mixed characters of the results of the linear-chain model and the dielectric continuum model. There exist localized interface modes at the transverse X point characteristic of the zinc-blende structure. A continuum model is proposed that can reproduce long-wavelength optical phonons almost exactly and is simple enough to be used in various applications such as calculation of quantities related to electron-phonon interactions.