Quantum Dot-Size Variation and Its Impact on Emission and Absorption Characteristics: An Experimental and Theoretical Modeling Investigation

Pal, D.; Stoleru, V. G.; Towe, E.; Firsov, D. A.

doi:10.1143/jjap.41.482

Cited by 23 publications

(18 citation statements)

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“…We use an analytical method that we have developed in order to determine the strain distribution for pyramidal and truncated pyramidal QDs. The ground state transition energy obtained for structure B is also consistent with our previous results [14], and those of others [16]. The analytic solutions for strain distributions are used as inputs to the electronic structure calculations.…”

Section: Resultssupporting

confidence: 86%

Quantum-Dot Molecules for Potential Applications in Terahertz Devices

Stoleru

Towe

et al. 2004

MRS Proc.

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The experimental and theoretical results of the electronic and optical properties of quantum dot artificial molecules (AMs), formed by pairs of electronically coupled quantum dots (QDs), are presented here in order to identify the necessary conditions for the development of new types of terahertz (THz) injection lasers based on intraband carrier transitions. We have performed analytical calculations to obtain the spatial strain distribution in vertically aligned (In,Ga)As QDs grown on (001) GaAs substrates by molecular beam epitaxy. Electronic coupling of the dots, mainly governed by the thickness of the separating barrier between the dot layers, is allowed due to the strain field-assisted self-organization of the dots. The calculated strain field reproduces our cross sectional high-resolution transmission electron microscopy observations very well. We further take into account the microscopic effects of the spatial strain distribution on carrier confinement potentials, and compute the electronic structure of the AM. Our calculations of the peak luminescence energies are in good agreement with our experimental results and those of others. The growth of quantum dot molecules represents a major step in tailoring the electronic and optical properties of the nanostructures.

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Section: Resultssupporting

confidence: 86%

Quantum-Dot Molecules for Potential Applications in Terahertz Devices

Stoleru

Towe

et al. 2004

MRS Proc.

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“…The attribute shell was also identified as being of significance for both cell viability and IC 50 BN models (≈7% and 10% variance reduction, respectively). QD shell affects the overall NP size (diameter) which in turn impacts the bandgap energy and various electron–electron interaction phenomena that can affect cellular interactions with QDs . The presence of a shell is paramount to preventing direct cellular interactions with the Cd core and Cd ion leaching from the core .…”

Section: Resultsmentioning

confidence: 99%

Bayesian Network Resource for Meta‐Analysis: Cellular Toxicity of Quantum Dots

Bilal

Liu

et al. 2019

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A web-based resource for meta-analysis of nanomaterials toxicity is developed whereby the utility of Bayesian networks (BNs) is illustrated for exploring the cellular toxicity of Cd-containing quantum dots (QDs). BN models are developed based on a dataset compiled from 517 publications comprising 3028 cell viability data samples and 837 IC 50 values. BN QD toxicity (BN-QDTox) models are developed using both continuous (i.e., numerical) and categorical attributes. Using these models, the most relevant attributes identified for correlating IC 50 are: QD diameter, exposure time, surface ligand, shell, assay type, surface modification, and surface charge, with the addition of QD concentration for the cell viability analysis. Data exploration via BN models further enables identification of possible association rules for QDs cellular toxicity. The BN models as web-based applications can be used for rapid intelligent query of the available body of evidence for a given nanomaterial and can be readily updated as the body of knowledge expands. Toxicity Models www.advancedsciencenews.com

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“…Em 1986, no entanto, Johannes Bednorz e Karl Müller (25) observaram que um determinado composto de óxido de cobre apresentava uma temperatura de transição supercondutora da ordem de 35 K, sendo que o maior valor de T c encontrado até aquele momento era de 23, 2 K para o composto Nb 3 Ge. Após essa descoberta pode-se dizer que foi iniciada uma verdadeira corrida para se encontrar materiais com maiores temperaturas de transição.…”

Section: Supercondutoresunclassified

“…Esses termos estão relacionados já que: Γ α = 2π ρ α |V α | 2 , sendo V α , de fato, o parâmetro de acoplamento entre nível e reservatório. 3 Essa escolha não é aleatória. Supondo que o acoplamento entre nível e reservatório acontece adiabaticamente, durante um tempo suficientemente longo, (de −∞ a t = 0, por exemplo), o nível ε v , com energia muito menor que µ L , estará preenchido ao final desse processo.…”

Section: Tensão Altaunclassified

“…O confinamento quântico em todas as dimensões, em contraposição aos poços (2D) e fios (1D) quânticos, dá origem a uma distribuição discreta dos níveis de energia (2) nos PQs. Suas propriedades ópticas e eletrônicas estão diretamente relacionadas ao seu tamanho, de modo que PQs de um mesmo material podem absorver e emitir luz em diversas faixas de frequências (3).…”

Section: Introdução Pontos Quânticosunclassified

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Reflexão de Andreev cruzada via dubleto de Autler-Townes em uma junção ponto quântico - supercondutor

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A Deus. Ao meu orientador, Prof. Fabrício Macedo de Souza, pela confiança depositada e encorajamento.Aos meus pais, Jarbas e Eni, e aos meus irmãos, Myller, Danielle e Daniel, pelo apoio e amizade.Ao meu marido, Wellington, pela paciência, amor e companheirismo de tantos anos. A todos os meus colegas do Grupo de Nanociências, de agora e de antigamente, por todo o companheirismo e incentivo, nesses quase 10 anos de pesquisa. Em especial quero agradecer ao meu colega doutorando Joelson Fernandes, pelas valiosas discussões e pela amizade. Aos professores do grupo, por todas as discussões, sugestões e convivência. Particularmente quero agradecer à professora Mariana Odashima pelo apoio profissional e pessoal. Também quero agradecer ao professor Ginetom Diniz, pelo grande auxílio com o trabalho e com meu crescimento profissional.A todos os meus amigos, dentro e fora do Instituto de Física da UFU, por nunca deixarem de me encorajar. Em especial, minhas amigas Silésia, Laiz e Rosy, por sempre me motivarem.A Universidade Federal de Uberlândia, por me oportunizar formação acadêmica de qualidade.Ao Instituto de Física e ao Programa de Pós-Graduação em Física, seus professores, técnicos e secretários, pela empenho e dedicação para com a qualidade do Programa e por todo auxílio.As agências de fomento: FAPEMIG e CAPES, pelo poio financeiro. AbstractThe theoretical and experimental knowledge accumulated in the last decades on semiconductors quantum dots (QDs) impulses the emergence of many current proposals for using them in hybrid systems. The ability to control their optoelectronic properties, as well as the control of fabrication techniques, made them the perfect candidates to compose junctions with superconductors (SCs), whose individual characteristics are also remarkable. These junctions can be simple, with a single QD coupled to a SC, or multiple: a connection of two superconducting terminals through a QD (a Josephson-like junction) and the junction of two QDs through a SC. The latter is known as a Cooper-pairs splitter, a device suggested as a source of entangled particles, for which is required the occurrence of crossed Andreev reflection (CAR) on the interfaces of the junction. Junctions of QDs with SCs and with topological SCs have also been proposed in two-level systems as qubits for both trivial and topological quantum computation. Despite the study of QD-SC junctions being currently in evidence, the literature review shows that the analysis of transient regime was little explored. Therefore, we address in this work the topic of time-dependent charge transport in a QD-SC-QD junction. By using non-equilibrium Green functions techniques, particularly, the Kadanoff-Baym formalism, we write down a set of coupled differential equations, which is numerically solved. Examining the Rabi oscillations that appears on the time evolution of electric current and QDs occupations, we were able to identify signatures of the scattering mechanisms through out the junction, i. e., direct tunnelling and CAR. Additionally, we propos...

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Quantum Dot-Size Variation and Its Impact on Emission and Absorption Characteristics: An Experimental and Theoretical Modeling Investigation

Cited by 23 publications

References 1 publication

Quantum-Dot Molecules for Potential Applications in Terahertz Devices

Quantum-Dot Molecules for Potential Applications in Terahertz Devices

Bayesian Network Resource for Meta‐Analysis: Cellular Toxicity of Quantum Dots

Reflexão de Andreev cruzada via dubleto de Autler-Townes em uma junção ponto quântico - supercondutor

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