ELECTRON-PHONON INTERACTION IN GAAS/ALAS SUPERLATTICES

Scattering rates of an electron in GaAs/AlAs superlattices are calculated in an envelope-function approximation which reproduces long-wavelength optical phonons almost completely. The polaron damping rate increases with decreasing layer-thickness at 300 K, while this dependence is smaller at 77 K. Intersubband relaxation rates decrease almost linearly as the layer thickness decreases. The results obtained in the dielectric continuum model agree quite well with those in the envelope-function approximation and even the bulk-phonon model explains the layer-thickness dependence reasonably well. This approximate model independence is explained by the completeness of the lattice vibration.