Top-gated germanium nanowire quantum dots in a few-electron regime
Sung-Kwon Shin, Shaoyun Huang, Naoki Fukata, and Koji Ishibashi
Top gated quantum dots (QDs) have been fabricated from n-type chemically synthesized germanium nanowires (GeNWs) by constricting its length with metal electrode contacts. With an intermediate HfO thin film, the constricted GeNW was fully covered by an Omega-shaped top-gate. The QD was probed and cha ... [Appl. Phys. Lett. 100, 073103 (2012)] published Mon Feb 13, 2012.
Circulating currents in a metallic ring with two quantum dots
E. V. Anda, G. Chiappe, and E. Louis
We analyze a system constituted by two single level quantum dots embedded in a metallic ring connected to external electrodes. The energy levels of the dots are controlled by an external gate potential. Additionally, the external electrodes are under the effect of an external applied potential. In t ... [J. Appl. Phys. 111, 033711 (2012)] published Mon Feb 13, 2012.
InGaN/GaN multiple-quantum-well light-emitting diodes grown on Si(111) substrates with ZrB(0001) buffer layers
Adam H. Blake, Derek Caselli, Christopher Durot, Jason Mueller, Eduardo Parra et al.
Multiple-quantum-well light-emitting diode (LED) structures of InGaN/GaN were grown by metalorganic chemical vapor deposition on Si(111) substrates via ZrB(0001) buffer layers and a GaN template comprising composite AlGaN (where x lies in the range from 0 to 1) transition layers to minimize cracking ... [J. Appl. Phys. 111, 033107 (2012)] published Mon Feb 13, 2012.
Resonant polaron-assisted tunneling of strongly interacting electrons through a single-level vibrating quantum dot
Gleb A. Skorobagatko
The problem of resonant transport of strongly interacting electrons through a one-dimensional single-level vibrating quantum dot is being considered. In this paper, we generalize the Komnik and Gogolin model [Phys. Rev. Lett. 90, 246403 (2003)] for the single-electron transistor with g=1/2 Luttinger ... [Phys. Rev. B 85, 075310 ] published .
Enhanced spontaneous emission from quantum dots in short photonic crystal waveguides
Thang Ba Hoang, Johannes Beetz, Leonardo Midolo, Matthias Skacel, Matthias Lermer et al.
We report a study of the quantum dot (QD) emission in short photonic crystal waveguides. We observe that the quantum dot photoluminescence intensity and decay rate are strongly enhanced when the emission energy is in resonance with Fabry-Perot (FP) cavity modes in the slow-light regime of the disper ... [Appl. Phys. Lett. 100, 061122 (2012)] published Fri Feb 10, 2012.
Single photon emission from InGaN/GaN quantum dots up to 50 K
Stefan Kremling, Christian Tessarek, Heiko Dartsch, Stephan Figge, Sven Hofling et al.
We have investigated the optical properties of single InGaN quantum dots (QDs) by means of microphotoluminescence ([mu]PL) spectroscopy. The QDs were grown on sapphire substrate using metal organic vapor phase epitaxy. Sharp and isolated single exciton emission lines in the blue spectral range were ... [Appl. Phys. Lett. 100, 061115 (2012)] published Thu Feb 9, 2012.
Room temperature single photon emission from an epitaxially grown quantum dot
O. Fedorych, C. Kruse, A. Ruban, D. Hommel, G. Bacher et al.
Single photon emission from an epitaxially grown quantum dot at room temperature is presented. CdSe/ZnSSe quantum dots are embedded into MgS barriers, providing dominant radiative recombination up to 300 K. Under continuous wave optical excitation, the autocorrelation function g(t) exhibits a sharp ... [Appl. Phys. Lett. 100, 061114 (2012)] published Thu Feb 9, 2012.
Ground State of the Parallel Double Quantum Dot System
Rok Zitko, Jernej Mravlje, and Kristjan Haule
We resolve the controversy regarding the ground state of the parallel double quantum dot system near half filling. The numerical renormalization group predicts an underscreened Kondo state with residual spin-1/2 magnetic moment, ln2 residual impurity entropy, and unitary conductance, while the Bethe ... [Phys. Rev. Lett. 108, 066602 ] published .
Carrier confinement in Ge/Si quantum dots grown with an intermediate ultrathin oxide layer
V. Kuryliuk, O. Korotchenkov, and A. Cantarero
We present computational results for strain effects on charge carrier confinement in GeSi quantum dots (QDs) grown on an oxidized Si surface. The strain and free carrier probability density distributions are obtained using the continuum elasticity theory and the effective-mass approximation implemen ... [Phys. Rev. B 85, 075406 ] published .
Quantum confinement in Si and Ge nanostructures
E. G. Barbagiovanni, D. J. Lockwood, P. J. Simpson, and L. V. Goncharova
We apply perturbative effective mass theory as a broadly applicable theoretical model for quantum confinement (QC) in all Si and Ge nanostructures including quantum wells (QWs), wires (Q-wires), and dots (QDs). Within the limits of strong, medium, and weak QC, valence and conduction band edge energy ... [J. Appl. Phys. 111, 034307 (2012)] published Wed Feb 8, 2012.
The role of surface defects in multi-exciton generation of lead selenide and silicon semiconductor quantum dots
Heather M. Jaeger, Sean Fischer, and Oleg V. Prezhdo
Multi-exciton generation (MEG), the creation of more than one electron-hole pair per photon absorbed, occurs for excitation energies greater than twice the bandgap (E). Imperfections on the surface of quantum dots, in the form of atomic vacancies or incomplete surface passivation, lead to less than ... [J. Chem. Phys. 136, 064701 (2012)] published Wed Feb 8, 2012.
Near-infrared nano-spectroscopy of semiconductor quantum dots using a phase-change mask layer
N. Tsumori, M. Takahashi, R. Kubota, P. Regreny, M. Gendry et al.
We propose a technique that uses an optical mask layer of a phase-change material (PCM), which is used for rewritable optical recording media, to achieve highly sensitive near-field imaging spectroscopy of single semiconductor quantum constituents at optical telecommunication wavelengths. An amorpho ... [Appl. Phys. Lett. 100, 063111 (2012)] published Wed Feb 8, 2012.
Highly tunable whispering gallery mode semiconductor lasers with controlled absorber
A. N. Baranov, G. Boissier, R. Teissier, A. M. Monakhov, V. V. Sherstnev et al.
Tunable semiconductor lasers with controlled absorber based on GaInAsSb/GaAlAsSb quantum well heterostructure was fabricated and experimentally studied. The emission wavelength of these lasers shifts from 2.24 to 2.28 [mu]m when the bias on the control contact decreases from the voltage equal to tha ... [Appl. Phys. Lett. 100, 061112 (2012)] published Tue Feb 7, 2012.
Exciton acoustic-phonon coupling in single GaN/AlN quantum dots
Irina A. Ostapenko, Gerald Honig, Sven Rodt, Andrei Schliwa, Axel Hoffmann et al.
Coupling of acoustic phonons to excitons in single wurtzite-type GaN/AlN quantum dots is investigated in detail by cathodoluminescence experiments and compared to theory. Numerical simulations of the coupling in the framework of the independent Boson model with realistic wave functions based on 8-ba ... [Phys. Rev. B 85, 081303 ] published .
The effect of In-flush on the optical anisotropy of InAs/GaAs quantum dots
M. Molas, K. Golasa, K. Kuldova, J. Borysiuk, A. Babinski et al.
The effect of the In-flush technique on the optical anisotropy of InAs/GaAs quantum dots (QDs) has been investigated. The anisotropy was deduced from low temperature microluminescence measurements of the splitting of the emission lines related to single neutral excitons confined to the QDs. It was f ... [J. Appl. Phys. 111, 033510 (2012)] published Mon Feb 6, 2012.
Thermal and structural dependence of the band gap of quantum dots measured by a transparent film heater
Ju Yeon Woo, Suraj Kumar Tripathy, Kyungnam Kim, and Chang-Soo Han
We report the temperature dependence of the optical absorption and emission spectra of quantum dots (QDs) for three different nanocrystal (NC) structures (CdSe core, CdSe/CdS core/shell, and CdSe/CdS/ZnS core/multishell) in the solid film state. For this, a transparent single-walled carbon nanotube ... [Appl. Phys. Lett. 100, 063105 (2012)] published Mon Feb 6, 2012.
Large enhancement of thermoelectric effects in a double quantum dot system due to interference and Coulomb correlation phenomena
Piotr Trocha and Jozef Barnaś
Thermoelectric effects in a double quantum dot system coupled to external magnetic/nonmagnetic leads are investigated theoretically. The basic thermoelectric transport characteristics, like thermopower, electronic contribution to heat conductance, and the corresponding figure of merit, have been cal ... [Phys. Rev. B 85, 085408 ] published .
Negative trion emission spectrum in stacked quantum dots: External electric field and valence band mixing
W. J. Pasek and B. Szafran
We study the negatively charged exciton trion in stacked quantum dots by the configuration interaction method. We discuss the trion recombination spectrum in an external electric field (F) and look for the effects of the valence band mixing leading to the antibonding-hole ground-state formation in t ... [Phys. Rev. B 85, 085301 ] published .
Alloy and heterostructure architectures as promising tools for controlling electronic properties of semiconductor quantum dots
Roman Vaxenburg and Efrat Lifshitz
Tunability of energy levels and wavefunctions of carriers in colloidal quantum dots (CQDs) has a marked effect on numerous physical aspects, such as Coulomb interactions and charge separation, which in turn has a direct impact on the functioning of CQD-based opto-electronic devices. The electronic p ... [Phys. Rev. B 85, 075304 ] published .
Resonance-hybrid states in a triple quantum dot
S. Amaha, T. Hatano, H. Tamura, S. Teraoka, T. Kubo et al.
Delocalization by resonance between contributing structures explains the enhanced stability of resonance-hybrid molecules. Here we report the realization of resonance-hybrid states in a few-electron triple quantum dot (TQD) obseved by excitation spectroscopy. The stabilization of the resonance-hybri ... [Phys. Rev. B 85, 081301 ] published .
Time scales in the dynamics of an interacting quantum dot
L. Debora Contreras-Pulido, Janine Splettstoesser, Michele Governale, Jurgen Konig, and Markus Buttiker
We analyze the dynamics of a single-level quantum dot with Coulomb interaction, weakly tunnel coupled to an electronic reservoir, after it has been brought out of equilibrium, e.g., by a step-pulse potential. We investigate the exponential decay toward the equilibrium state, which is governed by thr ... [Phys. Rev. B 85, 075301 ] published .