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Summary form only given. We report on the first low temperature near-field luminescence investigation of a novel coupled wire-dot structure, allowing the assignment of different optical transition energies to different spatial areas of the sample and demonstrating carrier transport along the QWR into the dot. The schematic top view of the structure is shown together with an overview far-field photoluminescence...
Summary form only given. Nanoscale structures can be tailored to provide enhanced, nanoscale near-field optics. For example, high-quality GaAs quantum dots can be fabricated by self-formed growth near the apex of AlGaAs tetrahedral pyramids. Photoluminescence studies have shown a thousand-fold enhancement of the far-field emission of an embedded quantum dot. This large enhancement arises because the...
Summary form only given. The difficulty of T-shaped quantum wires (T-QWRs) and lasers formed by the cleaved-edge overgrowth (CEO) method, the two-step-growth method combined by in-situ cleavage, with molecular beam epitaxy lies in the growth of high-quality layers on [110] cleaved surfaces We investigated local electronic-states in GaAs T-QWRs and constituent GaAs [110] QWs using high-resolution micro...
Summary form only given. We have performed real-time and orientation resolved measurements of single fluorescent molecules (DiIC/sub 18/) in thin films of PMMA and polystyrene at ambient and reduced oxygen conditions. Fluorescent time trajectories of single molecules have been recorded using a two-channel near-field optical microscope, with 30-/spl mu/s real-time resolution.
Summary form only given. In the contribution, we show clear evidence that photonic crystals (PC) can be used in ultrasmall integrated optics to cascade two elements, in this case a cavity and a waveguide. We use as a basis PC a triangular array of holes of period a=220-260 nm etched through an AlGaAs planar waveguide, in which we define a hexagonal cavity of side h=7a (H7 cavity), and a guide with...
Summary form only given. The fine structures of magnetoexcitons in single quantum dots are under intensive research. It is now well known that the doublet structures in the exciton photoluminescence arise from the long-range part of the electron-hole exchange interaction and those doublet states have mutually orthogonal linear polarizations due to the anisotropic shape of each quantum dot. Under a...
Summary form only given. Quantum dots, often referred to as artificial atoms, open the field of quantum resolved spectroscopy to semiconductor physics. Using near-field microscopy through electron beam written shadow masks, we have isolated single InGaAs quantum dots for advanced spectroscopic analysis. In power-dependent low-temperature photoluminescence studies, we have investigated the influence...
Summary form only given. In strongly confined quantum dots the size of the Hilbert space is restricted to the number of confined electronic shells. Recent progress in the fabrication of self-assembled quantum dots has resulted in the possibility of controlling precisely this number as well as the energy separation between the shells. However, the rather large inhomogeneous broadening of the dot spectra...
Summary form only given. Semiconductor quantum dots (QDs) of nanometer size are of particular interest because carriers are confined there within dimensions smaller than their de-Broglie wavelength. We present the first measurements of near field time-resolved spectroscopy via single semiconductor QD, together with a theoretical model, which quantitatively describes our measurements.
Summary form only given. Recent studies have been carried out on the resonant response from single interface fluctuation quantum dots. Such a discrete-level model yields unique signatures under strong resonant driving, including Rabi oscillations. To date, Rabi oscillations (excluding microcavity studies) have only been reported for two-dimensional excitonic systems. We present data showing the nonlinear...
Summary form only given. The spectroscopy of individual quantum dots (QDs) using optical micro-probing techniques is opening up possibilities of various applications based on the physics of the zero-dimensional (0D) semiconductor structures. Self-assembled quantum dots (SAQDs) are also attractive 0D structures, where strong confinement on a no-meter scale can be realized. Here, we carried out time-correlation...
Summary form only given. The optical response of self-assembled quantum dots (SAQDs) has been an area of extensive research in recent years, driven both by an interest in the basic physics of these strongly confined systems, and by the possibility of practical applications for such structures. There have been several studies of carrier relaxation in these systems, including differential transmission,...
Summary form only given. Enhanced light extraction is obtained from a light-emitting diode (LED) containing a two-dimensional (2D) photonic band gap (PBG) crystal. The 2D photonic crystal prohibits the propagation of light within a certain range of frequencies in the plane of the PBG. Several methods to modify light emission using a 2D photonic crystal have been studied. A 2D PBG is fabricated in...
Summary form only given. The homogeneous linewidth of excitonic transitions is a parameter of fundamental physical importance. In self-assembled quantum dot systems, a strong inhomogeneous broadening due to dot size fluctuations masks the homogeneous linewidth associated with transitions between individual states. The homogeneous and inhomogeneous broadening of InGaAs quantum dot luminescence is of...
Summary form only given. Recent development of micro-photoluminescence (/spl mu/-PL) spectroscopy has enabled us to observe photoluminescence from a single quantum dot, which has sharp homogeneous linewidth and long coherence time. We report on the /spl mu/-PL spectra of single GaAs/AlGaAs quantum dots grown on a (411)A surface of a GaAs substrate. We have observed sharp luminescence lines originating...
Summary form only given. The physical nature of photoluminescence (PL) from semiconductor nanocrystals has been a subject of considerable debate. Earlier studies using organically-capped nanocrystals have shown that the PL arises primarily from dark excitonic states with a radiative lifetime of order microseconds. Recent advances in developing inorganically-capped nanocrystals have led to much improved...
Summary form only given. Recent progress in microfabrication involving, etching processes makes it possible to engineer three-dimensional (3D) nanostructures from MBE-grown planar Fabry-Perot micro-cavities. The optical mode is confined laterally by implementing a thin dielectric (native oxide) aperture layer on top of the cavity spacer. The sample under investigation consists of a 16 period GaAs/AlAs...
Summary form only given. The sample investigated here was grown by molecular-beam epitaxy on a 300-nm-thick GaAs buffer on a GaAs [001] substrate. This sample contains a single 4-nm-thin ZnSe quantum well with quaternary Zn/sub 1-x/Mg/sub x/S/sub y/Se/sub 1-y/ (ZnMgSSe) barriers with x/spl ap/0.1 and y/spl ap/0.1 on either side. The ZnMgSSe cap layer is only 17 nm thick and the ZnMgSSe barrier layer...
Summary form only given. Growth of GaN-based self-assembled quantum dots (QDs) has received great attention for application to blue light emitting lasers. Lasing action from a photo-excited InGaN QD laser at room temperature was recently reported. To confirm the effect of quantum-mechanically localized states in the QDs, discrete energy levels should be evidenced. However, there has been no report...
Summary from only given. In recent years, many studies of the electronic states in self-assembled quantum dots (SAQDs) using single dot spectroscopy have been reported. PL spectra measured by single dot spectroscopy show discrete and sharp peaks which indicate 0D confinement of carriers. At higher excitation powers, PL spectra show the interesting phenomena where we see many peaks to be emerged. Delkel...
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