Coherent Excitation Spectroscopy of Disordered Quantum-Well Structures

We study semiconductor quantum-well samples with different disorder strengths by coherent excitation spectroscopy with particular emphasis on disorder-mediated couplings of exciton subensembles. Our experiments show that there is no coherent coupling of excitons in different quantum islands and in a strongly inhomogeneously broadened sample. Latest results with polarization-resolved coherent excitation spectroscopy indicate a disorder-induced dephasing of biexcitons in the inhomogeneously broadened sample.