scholarly journals Resonant photoluminescence and excitation spectroscopy of CdSe/ZnSe and CdTe/ZnTe self-assembled quantum dots

2002 ◽  
Vol 737 ◽  
Author(s):  
T. A. Nguyen ◽  
S. Mackowski ◽  
H. Rho ◽  
H. E. Jackson ◽  
L. M. Smith ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Excited State ◽  
Ground State ◽  
State Transition ◽  
Longitudinal Optical ◽  
Photoluminescence Spectra ◽  
Single Quantum Dots ◽  
Major Carrier ◽  
Excitation Mechanisms ◽  
Self Assembled

ABSTRACTWe show that two major carrier excitation mechanisms are present in II-VI self-assembled quantum dots. The first one is related to direct excited state – ground state transition. It manifests itself by the presence of sharp and intense lines in the excitation spectrum measured from single quantum dots. Apart from these lines, we also observe up to four much broader excitation lines. The energy spacing between these lines indicates that they are associated with absorption related to longitudinal optical phonons. By analyzing resonantly excited photoluminescence spectra, we are able to separate the contributions from these two mechanisms. In the case of CdTe dots, the excited state – ground state relaxation is important for all dots in ensemble, while phonon-assisted processes are dominant for the dots with smaller lateral size.

scholarly journals Temperature dependence of ultrasharp luminescence lines in AlyIn1−yAs/AlxGa1−xAs self-assembled quantum dots

1996 ◽  
Vol 74 (S1) ◽  
pp. 216-219 ◽  
Author(s):  
S. Raymond ◽  
S. Fafard ◽  
S. Charbonneau
Keyword(s):  
Quantum Dots ◽  
Ground State ◽  
State Transition ◽  
Thermionic Emission ◽  
Excitation Density ◽  
High Excitation ◽  
Temperature Dependent ◽  
Time Resolved ◽  
Self Assembled ◽  
Intensity Evolution

Ensembles of~600 AlyIn1−yAs/AlxGa1−xAs self-assembled quantum dots (QDs) are investigated using photoluminescence (PL) and time-resolved PL in the visible. At very low excitation intensities, the PL spectrum shows multiple ultranarrow luminescence lines (FWHM ~200 μeV), which are attributed to the ground-state transition of a few dots (4 or less). The temperature and intensity evolution of these sharp lines is then monitored. The temperature-dependent measurements show that the line width and lifetime of the narrow lines remain constant up to the onset of thermionic, emission. Intensity-dependent measurements show that for high excitation density the collective background, emitted by the ensemble of QDs, is enhanced relative to the amplitude of individual ultranarrow lines.

Influence of bimodal distribution and excited state emission on photoluminescence spectra of InAs self-assembled quantum dots

2013 ◽  
Vol 137 ◽  
pp. 22-27 ◽  
Author(s):  
Flavio Franchello ◽  
Leonardo D. de Souza ◽  
Edson Laureto ◽  
Alain A. Quivy ◽  
Ivan F.L. Dias ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Excited State ◽  
Bimodal Distribution ◽  
Photoluminescence Spectra ◽  
Self Assembled

Photoreflectance Investigation of Inas/Gaas Self-Assembled Quantum Dots Grown by Almbe

1999 ◽  
Vol 583 ◽  
Author(s):  
M. Geddol ◽  
R. Ferrinm ◽  
G. Guizzetti ◽  
M. Patrini ◽  
S. Franchi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ground State ◽  
Molecular Beam ◽  
State Transition ◽  
Transition Energy ◽  
Atomic Layer ◽  
Optical Response ◽  
Spectral Features ◽  
Modulation Spectroscopy ◽  
Self Assembled

AbstractPhotoreflectance measurements have been performed in the 0.8–1.5 eV photon energy range and at temperatures from 80 to 300 K on stacked layers of InAs/GaAs self-assembled quantum dots (QDs) grown by Atomic-Layer Molecular Beam Epitaxy. The spectral features due to the QD optical response were analyzed by using lineshape models characteristic of modulation spectroscopy of confined systems. The dependence of the ground state transition energy on the number of stacked QD layers is investigated and it is shown that Coulomb interaction can account for the observed different behavior of the ensemble optical response of QD families characterized by different morphologies and coexisting in the same sample.

Effects of Rapid Thermal Annealing on the Intersubband Energy Spacing of Self-Assembled InAs/Gaas Quantum Dots

1999 ◽  
Vol 588 ◽  
Author(s):  
X. C. Wang ◽  
S. J. Chua ◽  
S. J. Xu ◽  
Z. H. Zhang
Keyword(s):  
Quantum Dots ◽  
Excited State ◽  
High Resolution ◽  
Thermal Treatment ◽  
Ground State ◽  
Infrared Detectors ◽  
Blue Shift ◽  
X Ray Diffraction ◽  
X Ray ◽  
Self Assembled

AbstractIn this paper, we showed the significant reduction of the energy spacing between ground state and excited state emissions from InAs/GaAs quantum dots due to interface interdiffusion induced by thermal treatment. In addition, the strong narrowing of the luminescence linewidth of the ground state and excited state emissions from the InAs dot layers for the annealed samples indicates an improvement of the size-distribution of the QDs. Large blue-shift of the energy positions of both emissions was also observed. High resolution X-Ray diffraction experiments give strong evidence of the interface atom interdiffusion in the annealed samples. This work shows ability to tune the wavelength for applications like infrared detectors and lasers based on intrasubband transitions of self-assembled QDs.

scholarly journals Увеличение эффективности тандема полупроводниковый лазер-оптический усилитель на основе самоорганизующихся 8s квантовых точек

2021 ◽  
Vol 55 (12) ◽  
pp. 1223
Author(s):  
А.Е. Жуков ◽  
Н.В. Крыжановская ◽  
Э.И. Моисеев ◽  
А.С. Драгунова ◽  
А.М. Надточий ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Excited State ◽  
Laser Diode ◽  
Ground State ◽  
Semiconductor Optical Amplifier ◽  
Optical Transition ◽  
Optical Amplifier ◽  
Rate Equations ◽  
Resonator Length ◽  
Optimal Value

The rate equations are used to analyze the characteristics of a tandem consisting of a laser diode and a semiconductor optical amplifier made of a single heterostructure with quantum dots. The optimal value of the current distribution coefficient the amplifier and the laser, as well as the optimal resonator length that provides the highest output power of the tandem were determined. It is shown that the use of the tandem allows, at the same total consumed current, to significantly (more than 4 times for 1 A) increase the power emitted through the ground-state optical transition in comparison with that achievable with a laser diode solely being limited by the onset of lasing through an excited-state optical transition.

Polarization Spectroscopy of Charged Single Self-Assembled Quantum Dots

2003 ◽  
Vol 789 ◽  
Author(s):  
Morgan E. Ware ◽  
Allan Bracker ◽  
Daniel Gammon ◽  
David Gershoni
Keyword(s):  
Quantum Dots ◽  
Circular Polarization ◽  
Schottky Diode ◽  
Heavy Hole ◽  
Photoluminescence Spectra ◽  
Polarization Spectroscopy ◽  
Charged Exciton ◽  
Self Assembled ◽  
Positively Charged

ABSTRACTWe have demonstrated single dot spectroscopy of InAs/GaAs self-assembled quantum dots embedded in a bias controlled Schottky diode. The photoluminescence spectra exhibit discrete lines depending on bias, which we attribute to the recombination of positively charged, neutral, and negatively charged confined excitons. With excitation directly into the dot, large circular polarization memory is exhibited by the two charged exciton (trion) lines. This indicates long spin lifetimes for both the electron and the heavy hole in the quantum dots.

LIFETIME MEASUREMENTS OF STATES IN O18 AND Ne22

1964 ◽  
Vol 42 (6) ◽  
pp. 1311-1323 ◽  
Author(s):  
M. A. Eswaran ◽  
C. Broude
Keyword(s):  
Excited State ◽  
Ground State ◽  
Doppler Shift ◽  
State Transition ◽  
Branching Ratios ◽  
Ground State Transition ◽  
Lifetime Measurements ◽  
Doppler Shift Attenuation ◽  
First Excited State ◽  
Doppler Shift Attenuation Method

Lifetime measurements have been made by the Doppler-shift attenuation method for the 1.98-, 3.63-, 3.92-, and 4.45-Mev states in O18 and the 1.28-, 3.34-, and 4.47-Mev states in Ne22, excited by the reactions Li7(C12, pγ)O18 and Li7(O16, pγ)Ne22. Branching ratios have also been measured. The results are tabulated.[Formula: see text]The decay of the 3.92-Mev state in O18 is 93.5% to the 1.98-Mev state and 6.5% to the ground state and of the 4.45-Mev state 74% to the 3.63-Mev state, 26% to the 1.98-Mev state, and less than 2% to the ground state. In Ne22, the ground-state transition from the 4.47-Mev state is less than 2% of the decay to the first excited state.

Line broadening of excitonic complexes in self-assembled GaAs/AlGaAs single quantum dots

2009 ◽  
Vol 6 (4) ◽  
pp. 886-889 ◽  
Author(s):  
M. Abbarchi ◽  
C. Mastrandrea ◽  
T. Kuroda ◽  
A. Vinattieri ◽  
T. Mano ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Line Broadening ◽  
Single Quantum ◽  
Single Quantum Dots ◽  
Self Assembled

Ground-state transition in few-electron quantum dots observed by magnetophotoluminescence

2003 ◽  
Vol 68 (7) ◽  
Author(s):  
Y. H. Zhang ◽  
A. S. Plaut ◽  
J. Weis ◽  
J. P. Harbison ◽  
L. T. Florez ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ground State ◽  
State Transition ◽  
Ground State Transition ◽  
Electron Quantum
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