Phonon-assisted Gamma -X transition rates in type-II superlattices.

The \ensuremath{\Gamma}-X transition rate for electrons in type-II superlattices is calculated for the case of optical-phonon emission. The tight-binding method for electronic band structure and the dielectric continuum model for phonons are used. The relative strength of scattering due to different phonon modes is examined for varying superlattice dimensions. The scattering rate is highest when the energy separation between the \ensuremath{\Gamma} and X levels is smallest, and decreases quickly as the separation increases. It is found that the strongest scattering rate is due to the emission of AlAs confined modes. Changing of parity with layer thickness and its effect on scattering are discussed.