PHONONS AND ELECTRON-PHONON INTERACTION IN GAAS QUANTUM WIRES

Phonon dispersions and potential profiles for thin rectangular GaAs wi res embedded in AlAs are calculated by means of a microscopic approach based on ab-initio microscopic force constants. Besides non-dispersiv e vibrations, well confined in GaAs, we find phonons with interface ch aracter along one or both of the in-plane directions, the latter inclu ding modes with maxima at the edges of the wire. While confined phonon potentials are well described within the dielectric continuum (DC) mo del, interface mode profiles turn out to be more complex. Not only mac roscopic models do not give analytic results in this case, but also nu merical implementations of the DC model reproduce only partially the m icroscopic results in the thin-wire regime.