NUMERICAL-STUDIES OF THE MARKOVIAN LIMIT OF THE QUANTUM KINETICS WITHPHONON-SCATTERING

The contribution of the Markovian component of a quantum-kinetic model to the carrier dynamics in photoexcited semiconductors is studied for intermediate evolution times. It is shown that for zero lattice tempe rature two unphysical effects arise due to an exponential damping in t he memory kernel, which results in the long-time limit in a Lorentz br oadened energy delta function. A finite carrier density is observed in the semiclassically forbidden energy region. Also the carriers with e nergy below the LO phonon threshold are in mutual exchange, having a n onvanishing total out-scattering rate. It is shown that in the inverse hyperbolic cosine damping model, which corrects the Lorentzian to an inverse hyperbolic cosine, such effects are suppressed. The results pr ovided by the two models are obtained by a Monte Carlo algorithm based on the iteration approach and allowing one-dimensional simulation.