Interplay between coherent and incoherent scattering in quantum well secondary emission

A microscopic theory for secondary emission of a semiconductor quantum well is presented where disorder and phonon scattering are treated consistently. Coherent and incoherent contributions to the secondary emission are computed for model systems with different degrees of disorder. The results show that the simultaneous influence of both scattering mechanisms is generally nonadditive, such that a full calculation is required to obtain reliable results. Only in strongly disorder dominated structures it is a reasonable approximation to model phonon scattering by a phenomenological decay time.