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Photoluminescence microscopy studies have detected synchronous-photoluminescence-intensity fluctuations along entire cadmium selenide quantum wires under continuous illumination. While similar photoluminescence blinking has been reported previously for semiconductor quantum dots and rods, the observation of synchronous blinking spanning the entire length of quantum wires, with diameters approximately 9 nm and lengths >5 microm, is remarkable. We propose a mechanism to account for the synchronous blinking that is based on a dynamic, photolytic filling of surface-trap sites.

The size dependence of the bandgap is the most identifiable aspect of quantum confinement in semiconductors; the bandgap increases as the nanostructure size decreases. The bandgaps in one-dimensional (1D)-confined wells, 2D-confined wires, and 3D-confined dots should evolve differently with size as a result of the differing dimensionality of confinement. However, no systematic experimental comparisons of analogous 1D, 2D or 3D confinement systems have been made. Here we report growth of indium phosphide (InP) quantum wires having diameters in the strong-confinement regime, and a comparison of their bandgaps with those previously reported for InP quantum dots. We provide theoretical evidence to establish that the quantum confinement observed in the InP wires is weakened to the expected extent, relative to that in InP dots, by the loss of one confinement dimension. Quantum wires sometimes behave as strings of quantum dots, and we propose an analysis to generally distinguish quantum-wire from quantum-dot behaviour.