PHONON-ASSISTED GAMMA-X TRANSITION RATES IN TYPE-II SUPERLATTICES

The 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 mode l for phonons are used. The relative strength of scattering due to dif ferent phonon modes is examined for varying superlattice dimensions. T he scattering rate is highest when the energy separation between the G AMMA and X levels is smallest, and decreases quickly as the separation increases. It is found that the strongest scattering rate is due to t he emission of AlAs confined modes. Changing of parity with layer thic kness and its effect on scattering are discussed.