Impact of size, shape, and composition on piezoelectric effects and electronic properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">In</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mi mathvariant="normal">Ga</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mi mathvariant="normal">As</mml:mi><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">Ga</mml:mi><mml:mi mathvariant="normal">As</mml:mi></mml:mrow></mml:math>quantum dots

Schliwa, A.; Winkelnkemper, Momme; Bimberg, D.

doi:10.1103/physrevb.76.205324

Cited by 262 publications

(229 citation statements)

References 49 publications

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“…Results on both InGaAs QDs [30] and c-plane InGaN QDs [15,16] reveal that dot shape anisotropy plays an important role and affects their properties quite significantly due to band mixing effects. Anisotropy affects the degree of quantum confinement, which causes energetic shifts in the | -, X〉 | -Y 〉 and | -Z〉 like state and, thus, their contribution to the band mixing effects for the hole ground state.…”

Section: Theoretical Calculations Of Dolpmentioning

confidence: 99%

“…Furthermore, it is well known that for InGaAs/GaAs QD, shape anisotropies have a significant effect upon the optical polarization properties of the QDs [30]. The experimental observation of high DOLPs raises the question of how strongly shape anisotropies affect the optical properties of self-assembled a-plane InGaN/GaN QDs and, thus, how reliable these QDs might be in generating highly polarized photons.…”

Section: Introductionmentioning

confidence: 99%

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Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

et al. 2017

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Abstract:We report the direct generation of linearly polarized single photons with a deterministic polarization axis in self-assembled quantum dots (QDs), achieved by the use of non-polar InGaN without complex device geometry engineering. Here, we present a comprehensive investigation of the polarization properties of these QDs and their origin with statistically significant experimental data and rigorous k·p modeling. The experimental study of 180 individual QDs allows us to compute an average polarization degree of 0.90, with a standard deviation of only 0.08. When coupled with theoretical insights, we show that these QDs are highly insensitive to size differences, shape anisotropies, and material content variations. Furthermore, 91% of the studied QDs exhibit a polarization axis along the crystal [1-100] axis, with the other 9% polarized orthogonal to this direction. These features give non-polar InGaN QDs unique advantages in polarization control over other materials, such as conventional polar nitride, InAs, or CdSe QDs. Hence, the ability to generate single photons with polarization control makes non-polar InGaN QDs highly attractive for quantum cryptography protocols.

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Section: Theoretical Calculations Of Dolpmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

et al. 2017

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“…Simpler models treating the quantum-dot confinement potential as a harmonic oscillator potential lead to a two-fold degenerate excited state due to the rotational symmetry with respect to the growth axis [NIE04]. More realistic models, however, lift this degeneracy [SCH07f]. Nevertheless, the difference in the localization energy between the two first excited states is in the order a few meV, and is thus neglected in the following.…”

Section: Maxwell-bloch Laser Rate Equationsmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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In this thesis the dynamics and performance of optoelectronic devices based on semiconductor quantum-dots are investigated.In the first part, the dynamics of quantum-dot lasers under external perturbations is discussed. Using a microscopically based balance equation model that incorporates detailed charge-carrier scattering dynamics and the possibility to describe nonequilibrium between intra-band electronic states, the relaxation oscillations of the quantum-dot laser are investigated. Three qualitatively different dynamic regimes are identified in dependence of the scattering rates -the "constantreservoir" regime for slow scattering, the "overdamped" regime, and the "synchronized" regime for high scattering -characterized by a varying degree of nonequilibrium between the quantum-dot and reservoir states.Important differences to conventional lasers are found in the modulation response and the dynamics in optical injection and feedback setups. Common theoretical models and approaches used to describe these applications are shown to yield inaccurate predictions, especially in the "constant-reservoir" and "overdamped" dynamic regimes. An important consequence is that the amplitude-phase coupling in quantum-dot lasers, commonly described by the α-factor, differs from conventional descriptions due to the desynchronization of gain and refractive index. While the α-factor describes bifurcations of fixed points accurately, it fails in describing dynamic solutions and overestimates the extent of complex dynamics. The observed low sensitivity to optical perturbations in quantum-dot lasers can therefore be attributed partly to the charge-carrier nonequilibrium. Three quantum-dot laser models on different levels of sophistication are presented that can accurately describe the quantum-dot nonequilibrium dynamics.In the second part of the thesis, the performance of quantum-dot semiconductor optical amplifiers is investigated, and two types of applications unique to quantum-dots as active medium are discussed. The ground and excited states of the quantum-dots allow an ultra-broad-band amplification of optical data streams. Amplified signals on the ground-state frequencies are shown to generally exhibit higher quality than on the excited state, due to a lower sensitivity of the groundstate to carrier-density variations. Nevertheless the quantum-dot amplifier is found to allow effective amplification on both frequency ranges. Furthermore, a parameter range is identified that allows for a simultaneous amplification of data signals on the ground and excited state in a counter-propagating setup.The long microscopically polarization dephasing times in quantum-dots are found to enable quantum-coherent interactions on a macroscopic scale at room-temperature. By comparison with experiments, the occurrence of Rabi-oscillations by amplification of ultra-short pulses is demonstrated. Quantum-dot based devices could therefore be used for future applications based on quantum-coherent effects.

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“…The asymmetry parameter present in the Burt-Foreman formalism but not in the Luttinger-Kohn formalism is shown to lead to changes in approximately Ϯ25 meV in the electronic band structures of InAs/GaAs. 18 Optoelectronic properties of InGaAs zinc-blende quantum dot with varying shape and size based on k ជ · p ជ theory have already been studied by Schliwa et al 19 and Veprek et al 20 However, so far, only a small selection of all possible transitions have been studied. In this work we apply the eightband model based on Burt-Foreman formalism derived in Ref.…”

Section: Introductionmentioning

confidence: 99%

Optical properties and optimization of electromagnetically induced transparency in strained InAs/GaAs quantum dot structures

et al. 2009

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Impact of size, shape, and composition on piezoelectric effects and electronic properties ofIn(Ga)As∕GaAsquantum dots

Cited by 262 publications

References 49 publications

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

Direct generation of linearly polarized single photons with a deterministic axis in quantum dots

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Optical properties and optimization of electromagnetically induced transparency in strained InAs/GaAs quantum dot structures

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