Optical and transport properties of CdSe/ZnSe self-organized nanostructures: 1-dimensional versus 3-dimensional quantum confinement

We present comprehensive studies of optical, structural and transport prope rties of molecular beam epitaxy grown CdSe/ZnSe self-organizing nanostructu res, aimed at elucidation of the intrinsic morphology of CdSe layers as a f unction of their nominal thickness (w). Particular attention has been paid to the layer thickness below the critical value(w < 3.0 monolayer (ML)). It is found that the layer morphology is transformed from pure two-dimensiona l objects at w! < 0.7 ML to extended (15-40 nm) Bat islands formed in the t hicker layers. The density of the islands increases with w, which is accomp anied by enhancement of the luminescence quantum efficiency. An optically p umped green laser is fabricated, taking advantage of the superior emission characteristics of the single CdSe layer with w = 2.8 ML, used as an active region. The threshold power density of 3.9 kW/cm(2) observed at 300 K is f ivefold less than that of the reference sample using a conventional ZnCdSe quantum-well active region.