TIME-CONVOLUTIONLESS REDUCED-DENSITY-OPERATOR THEORY OF HIGHLY EXCITED SEMICONDUCTORS(Session I : Cross-Disciplinary Physics, The 1st Tohwa University International Meeting on Statistical Physics Theories, Experiments and Computer Simulations)

Abstract

In this work, a reduced description of the dynamics of carriers in excited semiconductors is developed. Especially, the optical gain and the line shape function of a a quantum-well is studied taking into account the valence-band mixing, non-Markovian relaxation and the many-body effects. Conventional gain spectra calculated with the Lorentzian line shape function show two anomalous phenomena : unnatural absorption region below the band-gap energy and mismatch of the transparency point in the gain spectra with the Fermi-level separation, the latter suggesting that the carriers and the photons are not in thermal (or quasi) equilibrium. It is shown that the non-Markovian gain model with many-body effects removes the two anomalies associated with the Lorentzian line shape function with the proper choice of the correlation time.