POLARON-CYCLOTRON-RESONANCE SPECTRUM RESULTING FROM INTERFACE-PHONON AND SLAB-PHONON MODES IN A GAAS ALAS QUANTUM-WELL/

The effects of interface optical-phonon and confined slab LO-phonon mo des on the polaron cyclotron-resonance frequency are investigated for a GaAs/AlAs quantum well. Using degenerate second-order perturbation t heory, the polaron Landau levels are calculated and the polaron resona nt region is investigated. In order to know the relative importance of the different resonant frequencies we present a full calculation of t he magneto-optical absorption spectrum. At a fixed magnetic field we f ound four different peaks in the absorption spectrum. The relative osc illator strength of the different peaks changes with increasing magnet ic field. For comparative purposes, the polaron Landau levels and cycl otron mass are also calculated using only the bulk LO-phonon modes. Th e influence of the finiteness of the confinement potential is investig ated. We found that the interface-phonon modes influence the magnetopo laron resonance considerably near the optical-phonon frequencies for n arrow wells. In the limit of zero magnetic field we recover our previo us results and in the case of an infinite-barrier quantum well we are able to recover the results for a two- and three-dimensional system.