Microscopic theory for the optical properties of Coulomb-correlated semiconductors

A nonequilibrium Green's functions approach is presented for the consistent computation of semiconductor quantum well optical spectra including strong Coulomb correlations within the coupled photon and carrier system. Bethe-Salpeter-like equations are given for the optical response and recombination rates in the excited medium. Bandstructure, quantum-confinement, many-body and cavity resonator effects are included in the microscopic approach. The theory is applied to the description of absorption/gain, luminescence, single and two-beam photoluminescence excitation spectroscopy for arbitrary temperatures and carrier densities. Numerical results, showing good agreement with recent experiments, are presented for ITT-V and Il-VI materials, from the linear regime, characterized by excitonic effects to the high density case in which a strongly interacting electron-hole plasma is proposed as the dominant mechanism.