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We report on the carrier dynamics in InGaN/GaN disk-in-a-wire quantum dots with precisely controlled location and structural parameters, including diameter, thickness and material composition. We measured the time-integrated and…

Mesoscale and Nanoscale Physics · Physics 2015-01-07 Lei Zhang , Tyler A. Hill , Chu-Hsiang Teng , Brandon Demory , Pei-Cheng Ku , Hui Deng

We study quantum point contacts in two-dimensional topological insulators by means of quantum transport simulations for InAs/GaSb heterostructures and HgTe/(Hg,Cd)Te quantum wells. In InAs/GaSb, the density of edge states shows an…

Mesoscale and Nanoscale Physics · Physics 2016-05-17 Michał Papaj , Łukasz Cywiński , Jerzy Wróbel , Tomasz Dietl

We present results of correlated pseudopotential calculations of an exciton in a pair of vertically stacked InGaAs/GaAs dots. Competing effects of strain, geometry, and band mixing lead to many unexpected features missing in contemporary…

Materials Science · Physics 2012-03-08 Gabriel Bester , J. Shumway , Alex Zunger

Self consistent quantum approaches are used to study the instabilities of finite nuclear systems. The frequencies of multipole density fluctuations are determined as a function of dilution and temperature, for several isotopes. The spinodal…

Nuclear Theory · Physics 2009-11-07 M. Colonna , Ph. Chomaz , S. Ayik

The model systems for self-organized quantum dots formed from elemental and compound semiconductors, namely Ge grown on Si(001) and InAs on GaAs(001), are comparatively studied by scanning tunneling microscopy. It is shown that in both…

Other Condensed Matter · Physics 2007-05-23 G. Costantini , A. Rastelli , C. Manzano , R. Songmuang , O. G. Schmidt , H. v. Kaenel , K. Kern

We have performed time-resolved spectroscopy on InAs quantum dot ensembles in photonic crystal membranes. The influence of the photonic crystal is investigated by varying the lattice constant systematically. We observe a strong slow down of…

Mesoscale and Nanoscale Physics · Physics 2008-09-02 B. Julsgaard , J. Johansen , S. Stobbe , T. Stolberg-Rohr , T. Sünner , M. Kamp , A. Forchel , P. Lodahl

Using far-infrared spectroscopy, we investigate the excitations of self-organized InAs quantum dots as a function of the electron number per dot, 1<n<6, which is monitored in situ by capacitance spectroscopy. Whereas the well-known two-mode…

Condensed Matter · Physics 2009-10-28 M. Fricke , A. Lorke , J. P. Kotthaus , G. Medeiros-Ribeiro , P. M. Petroff

We present a study showing cooperative behavior of light emitting quantum dots at room temperature, with large increases in radiative decay rates and efficiencies, in the presence of small gold nanoparticles (1.5 - 4 nm radii) in low…

Mesoscale and Nanoscale Physics · Physics 2015-12-24 George J. Vathakkattil , M. Praveena , J. K. Basu , Murugesan Venkatapathi

The emission properties of single quantum dots in planar microcavities are studied experimentally and theoretically. Fivefold Enhanced spontaneous emission outside the microcavity is found for dots in resonance with the cavity mode,…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 G. Ramon , U. Mizrahi , N. Akopian , S. Braitbart , D. Gershoni , T. L. Reinecke , B. Gerardot , P. M. Petroff

We propose a novel scheme of solid state realization of a quantum computer based on single spin "enhancement mode" quantum dots as building blocks. In the enhancement quantum dots, just one electron can be brought into initially empty dot,…

Quantum Physics · Physics 2007-05-23 Y. B. Lyanda-Geller , M. J. Yang , C. H. Yang

In this paper, we have studied the strain, bandedge, and energy levels of cubic InGaAs quantum dots (QDs) surrounded by GaAs. It is shown that overall strain value is larger in InGaAs-GaAs interfaces, and also in smaller QDs. Also, it is…

Computational Physics · Physics 2015-11-04 Esfandiar Rajaei , Mahdi Ahmadi Borji

The Stranski-Krastanov (SK) growth-mode facilitates the self-assembly of quantum dots (QDs) using lattice-mismatched semiconductors, for instance InAs and GaAs. SK QDs are defect-free and can be embedded in heterostructures and…

Polarization resolved photoluminescence (PL) spectroscopy of individual CdTe/ZnTe quantum dots is investigated in the presence of external in-plane magnetic field. We find that the excitonic fine structure strongly depends on the magnitude…

Other Condensed Matter · Physics 2009-02-25 K. Kowalik , O. Krebs , A. Golnik , J. Suffczynski , P. Wojnar , J. Kossut , J. A. Gaj , P. Voisin

We describe the optical emission and the carrier dynamics of an ensemble of self-assembled GaAs quantum dots embedded in GaP(001). The QD formation is driven by the 3.6 % lattice mismatch between GaAs and GaP in Stranski-Krastanow mode…

Mesoscale and Nanoscale Physics · Physics 2016-03-23 S. Dadgostar , J. Schmidtbauer , T. Boeck , A. Torres , O. Martínez , J. Jiménez , J. W. Tomm , A. Mogilatenko , W. T. Masselink , F. Hatami

We report quantum dots fabricated on very shallow 2-dimensional electron gases, only 30 nm below the surface, in undoped GaAs/AlGaAs heterostructures grown by molecular beam epitaxy. Due to the absence of dopants, an improvement of more…

Mesoscale and Nanoscale Physics · Physics 2015-03-19 W. Y. Mak , F. Sfigakis , K. Das Gupta , O. Klochan , H. E. Beere , I. Farrer , J. P. Griffiths , G. A. C. Jones , A. R. Hamilton , D. A. Ritchie

Near-surface two-dimensional electron gases on the topological insulator Bi$_2$Te$_2$Se are induced by electron doping and studied by angle-resolved photoemission spectroscopy. A pronounced spin-orbit splitting is observed for these states.…

We present results from a theoretical and experimental study of spin-splitting in small open lateral quantum dots (i.e. in the regime when the dot is connected to the reservoirs via leads that support one or more propagating modes). We…

Mesoscale and Nanoscale Physics · Physics 2008-04-04 M. Evaldsson , I. V. Zozoulenko , M. Ciorga , P. Zawadzki , A. S. Sachrajda

In this work the intersubband electronic properties of two laterally coupled dome-shaped InAs/GaAs quantum dots were investigated. The envelope functions and eigenenergies were calculated as function of distance between the dots. The…

Materials Science · Physics 2013-12-12 A. Khaledi-Nasab , M. Shahzadeh , H. Amouzegar , M. Sabaeian

Long distance (1.4 micron) interaction of two different InAs/GaAs quantum dots in a photonic crystal microcavity is observed. Resonant optical excitation in the p-state of any of the quantum dots, results in an increase of the s-state…

We investigate the photoluminescence temperature dependence of individual InAs/InGaAlAs quantum dots emitting in the optical telecommunication bands. The high-density dots are grown on InP substrates and the selection of a smaller dot…

Mesoscale and Nanoscale Physics · Physics 2012-02-21 C. Hermannstädter , N. A. Jahan , J. -H. Huh , H. Sasakura , K. Akahane , M. Sasaki , I. Suemune