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Quantum Dots Embedded (quantum + dot_embedded)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Entanglement-buildup through charged-exciton decay in a semiconductor quantum dot

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2004
Ulrich Hohenester
Abstract We analyze the decay of a single-electron charged exciton in a quantum dot embedded in a field effect structure. We show how the quantum properties of the charged exciton are transferred through tunneling and relaxation to the spin entanglement between electrons in the dot and contact, carefully examine the proper theoretical description of the underlying scattering processes, and identify the pertinent disentanglement mechanisms. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Nano-floating gate capacitor with SnO2 quantum dots distributed in polyimide dielectrics

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2009
Dong Uk Lee
Abstract Self-assembled SnO2 quantum dots were fabricated by a chemical process between a BPDA-PDA polyamic acid and a Sn film. A nano-floating gate capacitor having metal,insulator,semiconductor structure has been formed on p-type Si substrate with SnO2 quantum dots and dielectric polymer layer. The size and density of fabricated SnO2 quantum dot were about 15 nm and 2.4 × 1011 cm,2, respectively. The electrical properties of the nano-floating gate capacitor have been investigated by measuring capacitance,voltage characteristics. Then, the flat-band voltage shift due to charging of the electron in SnO2 quantum dot was ranged from 1.2 V to 4 V. And the transmission electron microscopy and the optical absorption spectra have been measured to investigate the morphology and absorbance of the SnO2 quantum dots embedded in polyimide. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

On the way to InGaN quantum dots embedded into monolithic nitride cavities

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2007
K. Sebald
Abstract We present photoluminescence measurements on single InGaN quantum dots (QDs) grown by metalorganic vapor phase epitaxy, and on monolithicly grown GaN-based quantum well airpost pillar microcavities. The observed sharp emission lines of the quantum dots are characterized by excitation density dependent measurements. The photoluminescence of individual quantum dots can easily be detected for temperatures up to 150 K. The micro-photoluminescence measurements on microcavities reveal three-dimensional confined optical modes which are not seen in the luminescence of the simply planar cavity. The realization of rather temperature stable QDs as well as of nitride based microcavity samples are promising with respect to the intended implementation of QD layers into microcavities. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Influence of external magnetic field and confinement on spectrum rearrangement and exciton polaritons in optical microcavity

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009
Natalia Kaputkina
Abstract Influence of external magnetic field and confinement on direct and spatially-indirect excitons is studied. Exciton-photon interaction and exciton polariton formation are discussed for single and coupled quantum wells or quantum dots embedded in optical microcavity. Possibility to control polariton resonance, polariton splitting and polariton dispersion by magnetic field is studied analitically and numerically. Magnetic field changes effective mass of magnetoexciton. Magneticfield increases effective steepness of confining potential in quantum dots also. This leads to the transformation of exciton energy spectrum. At low temperatures spontaneous coherence and Kosterlitz-Thouless transition to superfluid state of exciton polaritons in the system of coupled quantum wells embedded in microcavity or Bose-Einstein condensation of exciton polaritons in the system of coupled quantum dots embedded in optical microcavity can take place. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

InAs/InP quantum dot photonic crystal microcavities

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2006
Simon Frédérick
Abstract We examine the optical mode structure of two-dimensional, photonic crystal microcavities based on triple missing hole defects in hexagonal symmetry, etched air-hole, suspended InP membranes. Polarisation dependent photoluminescence from InAs/InP quantum dots embedded within the cavities is used to explore mode energies and quality factors, Q, as a function of cavity design parameters. Optimised Q values are in excess of 7,500 for the modified y-dipole mode. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Influence of Mg on the temperature-dependent optical properties of CdTe quantum dots embedded in Zn0.7Mg0.3Te

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2004
Frank Tinjod
Abstract We compare the temperature-dependent optical properties of CdTe quantum dots with and without Mg in their Zn(Mg)Te barriers. The difficulty of forming CdTe dots on Zn0.7Mg0.3Te barriers (due to the decrease of the lattice mismatch) has been overcome by using a new technique based on an efficient reduction of the surface energy. Mg incorporation in the barriers leads to a better heavy-hole confinement along the growth axis, which is manifested in PL studies by both an extension of the radiative regime temperature range and a strong increase of the activation energy for the non-radiative mechanisms. However, the in-plane confinement is less enhanced, which leads to progressive inter-dot carrier transfers with increasing temperature, as evidenced directly by the analysis of photoluminescence intensities for different single dots. Our temperature-dependent data (time-resolved and micro-photoluminescence) indicate that this transfer consists of a thermally activated process via the two-dimensional wetting-layer states. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Spectral characteristics of single InAs/InGaAs quantum dots in a quantum well

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003
L. Worschech
Abstract Self assembled InAs quantum dots embedded in an InGaAs quantum well were grown by molecular beam epitaxy. At room temperature these dots in a well (DWELLS) have an emission wavelength of 1.3,,m. Small mesas with lateral sizes down to 200 × 200 nm2 were fabricated by electron beam lithography and etching techniques. By photoluminescence spectroscopy at low temperatures we observe narrow lines, which we attribute to excitons and excitonic molecules. Biexciton binding energies ranging between 3.5,5,meV are found. [source]