Search results for "QUANTUM DOT"

Enhancement of Electronic and Optical Properties of ZnO/Al2O3 Nanolaminate Coated Electrospun Nanofibers

2016

International audience; Nanolaminates are new class of promising nanomaterials with outstanding properties. Here we explored on the tuning of structural properties and the enhancement of electronic and optical properties of 1D PAN ZnO/Al2O3 nanolaminates designed by atomic layer deposition (ALD) and electrospinning. The influence of ZnO/Al2O3 bilayer thicknesses on the fundamental properties of 1D PAN ZnO/Al2O3 nanolaminates has been investigated. Due to the quantum confinement effect, the shift of XPS peaks to higher energies has been observed. Work function of Al2O3 was mostly independent of the bilayers number, whereas the ZnO work function decreased with an increase of the bilayer numbe…

Efficient excitation of photoluminescence in a two-dimensional waveguide consisting of a quantum dot-polymer sandwich-type structure

2014

International audience; In this Letter, we study a new kind of organic polymer waveguide numerically and experimentally by combining an ultrathin (10–50 nm) layer of compactly packed CdSe/ZnS core/shell colloidal quantum dots (QDs) sandwiched between two cladding poly(methyl methacrylate) (PMMA) layers. When a pumping laser beam is coupled into the waveguide edge, light is mostly confined around the QD layer, improving the efficiency of excitation. Moreover, the absence of losses in the claddings allows the propagation of the pumping laser beam along the entire waveguide length; hence, a high-intensity photoluminescence (PL) is produced. Furthermore, a novel fabrication technology is develo…

VIS-UV ZnCdO/ZnO multiple quantum well nanowires and the quantification of Cd diffusion.

2014

International audience; We report on the growth and microstructure analysis of high Cd content ZnCdO/ZnO multiple quantum wells (MQW) within a nanowire. Heterostructures consisting of ten wells with widths from 0.7 to 10nm are demonstrated, and show photoluminescence emissions ranging from 3.03 to 1.97eV. The wells with thicknesses⩽2nm have high radiative efficiencies compared to the thickest ones, consistent with the presence of quantum confinement. However, a nanometric analysis of the Cd profile along the heterostructures shows the presence of Cd diffusion from the ZnCdO well to the ZnO barrier. This phenomenon modifies the band structure and the optical properties of the heterostructure, an…

Dielectric Microspheres: Quantum Dots Luminescence Collection Enhancement and Nanoscopy by Dielectric Microspheres (Part. Part. Syst. Charact. 1/2020)

2020

Vertical stacks of small InAs/GaAs self-assembled dots: resonant and non-resonant excitation

2003

4 páginas, 2 figuras.-- PACS: 78.67.Hc; 73.21.La; 78.55.Cr.-- Proceedings of the International Conference on Superlattices, Nano-structures and Nano-devices ICSNN 2002.

Optical properties of nitride nanostructures

2010

In this paper we review some recent results on the optical properties of nitride nanostructures, in particular on GaN quantum dots (QDs) and InN nanocolumns (NCs). First, we will give a brief introduction on the particularities of vibrational modes of wurtzite. The GaN QDs, embedded in AlN, were grown by molecular beam epitaxy (MBE) in the Stransky-Krastanov mode on c- and a-plane 6H-SiC. We have studied the optical properties by means of photoluminescence (PL) and performed Raman scattering measurements to analyze the strain relaxation in the dots and the barrier, the effect of the internal electric fields, and the influence of specific growth parameters, like the influence of capping or t…

Influence of the InAs coverage on the phonon-assisted recombination in InAs/GaAs quantum dots

2002

6 páginas, 3 figuras.

Photoluminescence Enhancement of CdSe Quantum Dots: A Case of Organogel–Nanoparticle Symbiosis

2012

Highly fluorescent organogels (QD-organogel), prepared by combining a pseudopeptidic macrocycle and different types of CdSe quantum dots (QDs), have been characterized using a battery of optical and microscopic techniques. The results indicate that the presence of the QDs not only does not disrupt the supramolecular organization of the internal fibrillar network of the organogel to a significant extent, but it also decreases the critical concentration of gelator needed to form stable and thermoreversible organogels. Regarding the photophysical properties of the QDs, different trends were observed depending on the presence of a ZnS inorganic shell around the CdSe core. Thus, while the core-s…

Single photon emission from impurity centers in AlGaAs epilayers on Ge and Si substrates

2012

We show that the epitaxial growth of thin layers of AlGaAs on Ge and Si substrates allows to obtain single photon sources by exploiting the sparse and unintentional contamination with acceptors of the AlGaAs. Very bright and sharp single photoluminescence lines are observed in confocal microscopy. These lines behave very much as single excitons in quantum dots, but their implementation is by far much easier, since it does not require 3D nucleation. The photon antibunching is demonstrated by time resolved Hanbury Brown and Twiss measurements.

Two-Color Single-Photon Emission from In As Quantum Dots: Toward Logic Information Management Using Quantum Light

2014

In this work, we propose the use of the Hanbury-Brown and Twiss interferometric technique and a switchable two-color excitation method for evaluating the exciton and noncorrelated electron-hole dynamics associated with single photon emission from indium arsenide (InAs) self-assembled quantum dots (QDs). Using a microstate master equation model we demonstrate that our single QDs are described by nonlinear exciton dynamics. The simultaneous detection of two-color, single photon emission from InAs QDs using these nonlinear dynamics was used to design a NOT AND logic transference function. This computational functionality combines the advantages of working with light/photons input/output device…