| dc.description.abstract | in this thesis, we present a theoretical model of self-consistent driven bloch oscillations (scd
bo) of different types of charge carriers in biased semiconductor superlattices photoexcited
via ultra-short near-bandgap optical pulses. in this work, we wish to assess the influence of
the unbound continuum excitonic states on the is excitons. this is modelled by calculating
the full dynamics of is excitons and free electron-hole pairs, including the coulomb interaction
in a mean-field approximation. all the calculations are based on a recently-developed quasibosonic
treatment, by which we can study scd bo to infinite order in optical field without
loosing the crucial intraexcitonic electron-hole correlations. t he interaction of is excitons with
free electron-hole pairs is studied in both coherent and non-coherent systems. the numerical
results obtained are found to be partially in agreement with the experimental results reported
by f. loser et al. [ phys. rev. lett. 85, 4763 (2000) ]. however, we find several serious
discrepancies that indicate that a more complete treatment may have to be adopted in future
work. despite this, the work in this thesis provides some useful insights to the coherent response
of photoexcited semiconductor superlattices, and lays the ground work for fu tu re study. | |
