Quantum theory of phonon-assisted exciton formation and luminescence in semiconductor quantum wells

The phonon scattering assisted luminescence of semiconductor quantum well e xcitons after short pulse excitation is investigated. The presented analysi s is based on the low-density limit of a set of equations for quantum corre lation functions for electrons, phonons, and photons. The dynamics of the c orrelation functions describes the optical excitation and the decay of the coherent exciton polarization as well as the generation of an incoherent ex citon occupation and its luminescence decay. Numerical solutions of the equ ations of motion demonstrate strong competition effects of the exciton-phon on and the exciton-photon interaction on a picosecond time scale and lead t o a nonmonotonous temperature dependence of the time-resolved spontaneous e mission. The angle resolved emission resembles the generation and decay dyn amics of the exciton density for different in-plane momenta.