Effects of coupling on the structural properties of InxGa1-xAs/GaAs 1-D and 0-D sell-organized quantum structures

Self-organized, vertically stacked 1-D (quantum wires) and 0-D (quantum dots) low-dimensional materials can exhibit different optical and structural properties by virtue of the different strength of coupling, which is related to the thickness of the barrier layers. In this work these properties have been investigated for InxGa1-xAs/GaAs self-organized quantum structures using photoluminescence spectroscopy and transmission electron microscopy. In the case of the wires, the reduced thickness of the barrier does not influence the structural properties but just splits the uncoupled levels into symmetric and antisymmetric levels. In the case of the quantum dots, a critical change of the structural properties has been observed; in particular, a transition of the InxGa1-xAs quantum well from fully developed and defect free quantum dots to completely incoherent islands has been found as a consequence of the reduction of the barrier layer thickness.