Some Theoretical Studies Of Transport And Dynamics In Superlattices

In this thesis, we detailedly investigate the effect of elastic scattering on the electron dynamics and the current response in the two-band superlattice. We find elastic scattering can destroy the correlation between electrons. If an electron with k state is initially in one miniband, elastic scattering will make the difference of the probability band occupation tend to zero. If electrons initially are located at a single Wannier state, elastic scattering will make the difference of the probability band occupation tend to a constant which does not equal zero. The stable distribution in k space is just the same as the average distribution when no scattering.By studying the effect on the current response, we find elastic scattering can destroy the resonant peaks, make these peaks become wide and flat, which is in agreement with the experiment results. When the frequency of elastic scattering becomes large, the resonant peaks may be cancelled.We also investigate the dynamics of electrons and the quasi-energy spectrum of the system with strong interband coupling in real space, and obtain the phase-diagram in the parameter space. We find that when the band width is suppressed to be much smaller than the field frequency, dynamical localization can exist in the system. The corresponding regions for the occurrence of dynamical localization in the parameter space can be found in the phase-diagram.