Experimentally-Verified Modeling of InGaAs Quantum Dots

Kosarev, A.; Chaldyshev, V. V.; Cherkashin, Nikolay

doi:10.3390/nano12121967

Cited by 5 publications

(6 citation statements)

References 28 publications

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“…This provides a partial strain relaxation into the SAQD and reduces absolute peak values of deformation tensor components down to ε xx = 6.78% and ε zz = 4.49%, compared to 6.83%, as governed by the lattice constants mismatch. The results are in good agreement with the III–V SAQD strains discussed in the literature [ 67 , 68 , 69 , 70 ]. Note that the strain distribution is not significantly changed by the alloy composition variation.…”

Section: Resultssupporting

confidence: 90%

“…In this simple case, the deformation is almost localized in the thin strained layer, in contrast to the case of 3D SAQD, where the surrounding matrix layers are also strained [ 67 , 68 , 69 , 70 ]. The strain distribution over the SAQD volume and attached matrix material was calculated by the elastic energy minimization technique.…”

Section: Calculation Proceduresmentioning

confidence: 99%

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Novel InGaSb/AlP Quantum Dots for Non-Volatile Memories

Abramkin

Atuchin

2022

Nanomaterials

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Non-volatile memories based on the flash architecture with self-assembled III–V quantum dots (SAQDs) used as a floating gate are one of the prospective directions for universal memories. The central goal of this field is the search for a novel SAQD with hole localization energy (Eloc) sufficient for a long charge storage (10 years). In the present work, the hole states’ energy spectrum in novel InGaSb/AlP SAQDs was analyzed theoretically with a focus on its possible application in non-volatile memories. Material intermixing and formation of strained SAQDs from a GaxAl1−xSbyP1−y, InxAl1−xSbyP1−y or an InxGa1−xSbyP1−y alloy were taken into account. Critical sizes of SAQDs, with respect to the introduction of misfit dislocation as a function of alloy composition, were estimated using the force-balancing model. A variation in SAQDs’ composition together with dot sizes allowed us to find that the optimal configuration for the non-volatile memory application is GaSbP/AlP SAQDs with the 0.55–0.65 Sb fraction and a height of 4–4.5 nm, providing the Eloc value of 1.35–1.50 eV. Additionally, the hole energy spectra in unstrained InSb/AlP and GaSb/AlP SAQDs were calculated. Eloc values up to 1.65–1.70 eV were predicted, and that makes unstrained InGaSb/AlP SAQDs a prospective object for the non-volatile memory application.

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Section: Resultssupporting

confidence: 90%

Section: Calculation Proceduresmentioning

confidence: 99%

Novel InGaSb/AlP Quantum Dots for Non-Volatile Memories

Abramkin

Atuchin

2022

Nanomaterials

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“…The previously reported 29 , 39 composition/strain variation was obtained for the average QD through measurements carried out on an ensemble of QDs. HRXTEM measurements 26 , 32 , 49 , 50 reported earlier on a single QD showed an inhomogeneous indium distribution within the dot along the [001] growth direction. The in-plane indium distributions within the single QD along different directions are difficult in microscopic studies 26 , 32 , 49 , 50 and are assumed to be independent of in-plane crystallographic directions.…”

Section: Resultsmentioning

confidence: 91%

“…The maximum relative strain error in the strain mapping is ±0.24%. The strain map within QDs shows compressive strain, as expected, , except in the areas having maximum indium concentration, where the strain value decreases drastically. The directional anisotropies in the strain show a trend similar to that obtained in the composition map and show a flat compressive strain close to zero (∼−0.2 ± 0.24%).…”

Section: Resultsmentioning

confidence: 99%

Culling a Self-Assembled Quantum Dot as a Single-Photon Source Using X-ray Microscopy

Dey,

Sanyal,

Schropp

et al. 2023

ACS Nano

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Epitaxially grown self-assembled semiconductor quantum dots (QDs) with atom-like optical properties have emerged as the best choice for single-photon sources required for the development of quantum technology and quantum networks. Nondestructive selection of a single QD having desired structural, compositional, and optical characteristics is essential to obtain noise-free, fully indistinguishable single or entangled photons from single-photon emitters. Here, we show that the structural orientations and local compositional inhomogeneities within a single QD and the surrounding wet layer can be probed in a screening fashion by scanning X-ray diffraction microscopy and X-ray fluorescence with a few tens of nanometers-sized synchrotron radiation beam. The presented measurement protocol can be used to cull the best single QD from the enormous number of self-assembled dots grown simultaneously. The obtained results show that the elemental composition and resultant strain profiles of a QD are sensitive to in-plane crystallographic directions. We also observe that lattice expansion after a certain composition-limit introduces shear strain within a QD, enabling the possibility of controlled chiral-QD formation. Nanoscale chirality and compositional anisotropy, contradictory to common assumptions, need to be incorporated into existing theoretical models to predict the optical properties of single-photon sources and to further tune the epitaxial growth process of self-assembled quantum structures.

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“…In many epitaxially grown semiconductor heterosystems, such as InAs/GaAs materials, QDs can be created in the form of 3D islands already during epitaxial deposition following the Stranski–Krastanov mode. The islands, which appear as a result of 2D-3D transformation driven by a gain in elastic energy, have a pyramid-like shape after their capping and an anisotropic strain and composition distribution [ 12 , 13 ], providing 3D confinement of charge carriers [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Electromechanically Coupled III-N Quantum Dots

et al. 2023

Self Cite

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We exploit the three-dimensional (3D) character of the strain field created around InGaN islands formed within the multilayer structures spaced by a less than 1-nm-thick GaN layer for the creation of spatially correlated electronically coupled quantum dots (QDs). The laterally inhomogeneous vertical out-diffusion of In atoms during growth interruption is the basic mechanism for the formation of InGaN islands within as-deposited 2D layers. An anisotropic 3D strain field created in the first layer is sufficient to justify the vertical correlation of the islands formed in the upper layers spaced by a sufficiently thin GaN layer. When the thickness of a GaN spacer exceeds 1 nm, QDs from different layers under the same growth conditions emit independently and in the same wavelength range. When extremely thin (less than 1 nm), a GaN spacer is formed solely by applying short GI, and a double wavelength emission in the blue and green spectral ranges evidences the electromechanical coupling. With k→·p→ calculations including electromechanical fields, we model the optoelectronic properties of a structure with three InGaN lens-shaped QDs embedded in a GaN matrix, with three different configurations of In content. The profiles of the band structures are strongly dependent on the In content arrangement, and the quantum-confined Stark effect is significantly reduced in a structure with an increasing gradient of In content from the top to the bottom QD. This configuration exhibits carrier tunneling through the QDs, an increase of wave functions overlap, and evidence emerges of three distinct peaks in the spectral range.

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Experimentally-Verified Modeling of InGaAs Quantum Dots

Cited by 5 publications

References 28 publications

Novel InGaSb/AlP Quantum Dots for Non-Volatile Memories

Novel InGaSb/AlP Quantum Dots for Non-Volatile Memories

Culling a Self-Assembled Quantum Dot as a Single-Photon Source Using X-ray Microscopy

Electromechanically Coupled III-N Quantum Dots

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