Localization of excitons in pairs of natural dots induced by stacking faults in ZnSe quantum wells

Pairs of bright spots aligned parallel to the cleaved sample edges are obse rved in micro-photoluminescence intensity maps of ZnSe/ZnMgSSe quantum-well structures. Structural characterization by atomic-force microscopy, plan-v iew and cross-section transmission electron microscopy reveal that the enha nced radiative recombination is induced by pairs of stacking faults interse cting the quantum wells. In the case of Frank-type stacking faults the well s are enlarged by up to 12 bilayers leading to an efficient exciton localiz ation. This localization is much shallower in the case of Shock-ley-type st acking-fault Fairs.