Optical response of incoherent excitons in a dense electron-hole plasma

The influence of a fraction of relaxed excitons in a dense electron-hole plasma onto single particle properties and optical response is studied. Using Green's function techniques the optical susceptibility is expressed in terms of the T-matrix taking into account selfenergies of the carriers depending both on wave-number and energy. Numerical calculation of the T-matrix allows a detailed study of the Mott transition of the excitons. For temperatures above T greater than or equal to 40 X we find, that the Mott transition is already finished when the chemical potential crosses the exciton, preventing excitonic gain discussed for II-VI semiconductors.