Anomalous exciton lifetime by electromagnetic coupling of self-assembled InAs/GaAs quantum dots

Bogaart, EW Erik; Haverkort, Jem Jos

doi:10.1063/1.3354080

Cited by 3 publications

(4 citation statements)

References 38 publications

(66 reference statements)

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“…). Lithographically defined arrays of metallic nanoparticles, for example, show collective optical properties based on coupling through near-field and/or long-range dipolar interactions which strongly affect the single-particle plasmon resonance. , Similarly, long-range electromagnetic interactions have recently been observed in ensembles of epitaxially grown, semiconducting quantum dots . However, both the plasmonic and the epitaxial systems are limited by their fabrication process, which prevents the formation of heterogeneous superlattices or assemblies with high packing densities.…”

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confidence: 99%

“…2,3 Similarly, long-range electromagnetic interactions have recently been observed in ensembles of epitaxially grown, semiconducting quantum dots. 4 However, both the plasmonic and the epitaxial systems are limited by their fabrication process, which prevents the formation of heterogeneous superlattices or assemblies with high packing densities. An alternative to these lithographybased techniques is the bottom-up formation of NSLs by self-assembly of colloidal nanocrystals.…”

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confidence: 99%

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Giant and Broad-Band Absorption Enhancement in Colloidal Quantum Dot Monolayers through Dipolar Coupling

et al. 2013

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We demonstrate giant and broadband enhancement of the nanocrystal absorption cross section in close packed nanocrystal superlattices, which is the first report on a collective optical phenomenon in this type of self-assembled metamaterials to date. Colloidal nanocrystals (NC) are nanometer-sized semiconductor crystals obtained through a solution-based chemical synthesis. Apart from changing their composition, the optical properties (such as the absorption cross section and band gap) of the crystals can be tuned by varying their size, a direct result of strong quantum confinement in these structures. Moreover, their easy deposition allows for cheap bottom-up fabrication. For these reasons, nanocrystals are thought to be viable candidates for opto-electronic applications such as the fabrication of solar cells, light emitting diodes, photo-detectors, etc…. In such a device context, nanocrystals will very often be deposited in thin layers. However, as NCs are obtained through wet chemical synthesis, their optical properties (e.g. absorption cross section) are typically evaluated in solution using effective medium approaches, which assume no electromagnetic coupling between the absorbing dipoles. It is questionable that this assumption still holds for a close packed film of nanocrystals where those dipoles tend to couple through electromagnetic multipolar interactions. Using properties measured in solution to evaluate and study the performance and physics of thin film devices would therefore be incorrect, or at least a serious simplification. The basic idea of our approach to understand such close-packed dipoles is that of the 'coupled dipole model' (CD): the internal field of a particle in close proximity to other dipoles will be a superposition of the influence of the external field and the induced dipolar fields of the neighboring particles (see Figure 1, right). To quantify this idea, we will focus on the NC absorption cross section and we define an 'enhancement factor 'E', being the ratio between the absorption cross section in film to the cross section in solution and try to obtain E both through theory (via the coupled dipole model) and experiment 2. Figure 1: Close-up of nanocrystal monolayer (a: Image of monolayer on glass, b: AFM surface morphology, c: TEM image and d: TEM close-up showing local hexagonal order) and schematic of near-field coupling mechanism proposed in this work. To access the enhancement E experimentally, we measure the absorption spectrum of single and multiple close packed monolayers of nanocrystals on glass substrates (see Figure 1) using a standard UV-VIS-NIR spectrophotometer. The layers (essentially a meta-material) are deposited using Langmuir-Blodgett deposition 1 and are well defined (i.e. particle density and lattice symmetry are uniform over large areas). The enhancement predicted by our CD interpretation is substantial, leading to a size-dependent value of E up to 5 and 4 for PbS and CdSe monolayers respectively (see figure 2, left). To test our CD modeling, we use 2D single c...

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Giant and Broad-Band Absorption Enhancement in Colloidal Quantum Dot Monolayers through Dipolar Coupling

et al. 2013

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“…Optical properties of arrays and ensembles of quantum dots (QDs) continue to attract attention both from the theoretical [1][2][3][4][5] and experimental [6][7][8] point of view. This interest is certainly motivated to a large extent by the possible applications, in particular in laser structures 9,10 .…”

Section: Introductionmentioning

confidence: 99%

Superradiance and enhanced luminescence from ensembles of a few self-assembled quantum dots

Abdussalam

Machnikowski

2014

Phys. Rev. B

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We study theoretically the evolution of photoluminescence (PL) from homogeneous and inhomogeneous ensembles of a few coupled QDs. We discuss the relation between signals from a given QD ensemble under strong and weak excitation (full inversion and linear response regimes): A system homogeneous enough to manifest superradiant emission when strongly inverted shows a non-exponential decay of the PL signal under spatially coherent weak excitation. In an inhomogeneous ensemble the PL decay is always nearly exponential with a qualitatively different form of the time dependence in the two excitation regimes and with a higher rate under weak excitation.

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“…We are mostly interested in the time profile of the spontaneous emission intensity I (t) as well as in spatial profile in meridianal and azimuthal planes. The time variation of the population can be directly probed in time resolved transmission or differential reflectivity 58 measurements. The dynamics of the emission intensity can be recorded in a time resolved photoluminescence measurement.…”

Section: Basic Formalismmentioning

confidence: 99%

Collective spontaneous emission in coupled quantum dots: Physical mechanism of quantum nanoantenna

et al. 2012

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Anomalous exciton lifetime by electromagnetic coupling of self-assembled InAs/GaAs quantum dots

Cited by 3 publications

References 38 publications

Giant and Broad-Band Absorption Enhancement in Colloidal Quantum Dot Monolayers through Dipolar Coupling

Giant and Broad-Band Absorption Enhancement in Colloidal Quantum Dot Monolayers through Dipolar Coupling

Superradiance and enhanced luminescence from ensembles of a few self-assembled quantum dots

Collective spontaneous emission in coupled quantum dots: Physical mechanism of quantum nanoantenna

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