PHONONS AND ELECTRON-PHONON INTERACTION IN GAAS QUANTUM WIRES

Phonon dispersions and potential profiles for thin rectangular GaAs wires embedded in AlAs are calculated by means of a microscopic approach based on ab-initio microscopic force constants. Besides non-dispersive vibrations, well confined in GaAs, we find phonons with interface character along one or both of the in-plane directions, the latter including modes with maxima at the edges of the wire. While confined phonon potentials are well described within the dielectric continuum (DC) model, interface mode profiles turn out to be more complex. Not only macroscopic models do not give analytic results in this case, but also numerical implementations of the DC model reproduce only partially the microscopic results in the thin-wire regime.