Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot

Dekel, E.; Gershoni, D.; Ehrenfreund, E.; Spektor, Dalia M.; Garcı́a, J.M.; Petroff, P. M.

doi:10.1103/physrevlett.80.4991

Cited by 337 publications

(191 citation statements)

References 21 publications

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“…Similar approaches have been used in previous studies. 26,42 Figures 3 and 4 show spectral and temporal information from the same single QDC. A series of spectra taken at different excitation powers is displayed in Figure 3.…”

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confidence: 99%

Self-Assembled InGaAs Quantum Dot Clusters with Controlled Spatial and Spectral Properties

et al. 2012

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Planar quantum dot clusters (QDCs) consisting of six InGaAs quantum dots (QDs) formed around a GaAs nanomound are the most sophisticated self-assembled QDCs grown by molecular beam epitaxy thus far. We present the first photoluminescence measurements on individual hexa-QDCs with high spatial, spectral, and temporal resolution. In the best QDCs, the excitons confined in individual QDs are remarkably close in energy, exhibiting only a 10 meV spread. In addition, a biexponential decay profile and small variation in decay rates for different QDs was observed. The homogeneous energetics and dynamics suggest that the sizes, shapes, and composition of the QDs within these clusters are highly uniform.

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confidence: 99%

Self-Assembled InGaAs Quantum Dot Clusters with Controlled Spatial and Spectral Properties

et al. 2012

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“…First of all, the strain-induced quantum dot is physically isolated from the surrounding dots ͑which were completely removed͒. This is not the case in confocal PL experiments 6,[8][9][10] or scanning near-field optical microscopy ͑SNOM͒ experiments 7,11 carried out on two-dimensional arrays of dots, where carriers can diffuse and eventually populate neighboring dots. 15 Second, the dot forms in the quantum well under the InP stressor, far from the sample surface and from the sidewalls, so that no surface states and depletion layers affect the recombination.…”

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confidence: 99%

“…The atomiclike lines in the spectra were found to exhibit intriguing red-and blue-shifts, and new features are seen to appear and disappear depending on the number of injected electronhole pairs. [8][9][10] Such a complicated dynamics originates from the Coulomb correlation among pairs of carriers ͑excitons͒ confined in the dot, which is often neglected in the analysis of these experiments. In fact, we expect that whenever an electron-hole ͑e-h͒ pair is added to the dot, the energy states must change because of the resulting additional Coulomb interactions.…”

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confidence: 99%

Effects of few-particle interaction on the atomiclike levels of a single strain-induced quantum dot

et al. 2000

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“…1 Methods to optically interrogate single QDs include physical isolation via microfabricated mesas 2 and diffraction-limited confocal optical microscopy. 3 Despite the technical challenges involved in developing tools for use at cryogenic temperatures, solid immersion lenses 4 have been implemented to improve the efficiency of light collection, while near-field scanning optical microscopy ͑NSOM͒ has been used to achieve sub-100 nm spatial resolution. 5 In this letter, we examine the use of optical fiber taper waveguides as a near-field optic for performing single QD spectroscopy.…”

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Single quantum dot spectroscopy using a fiber taper waveguide near-field optic

Srinivasan

Painter

Stintz

et al. 2007

Applied Physics Letters

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Photoluminescence spectroscopy of single InAs quantum dots at cryogenic temperatures ͑ϳ14 K͒ is performed using a micron-scale optical fiber taper waveguide as a near-field optic. A lower bound on the measured collection efficiency of quantum dot spontaneous emission into the fundamental guided mode of the fiber taper is estimated at 0.1%, and spatially resolved measurements with ϳ600 nm resolution are obtained by varying the taper position with respect to the sample and using the fiber taper for both the pump and collection channels. 4 have been implemented to improve the efficiency of light collection, while near-field scanning optical microscopy ͑NSOM͒ has been used to achieve sub-100 nm spatial resolution. 5 In this letter, we examine the use of optical fiber taper waveguides as a near-field optic for performing single QD spectroscopy. These micron-scale silica waveguides have been used in many studies of optical microcavities, beginning as an efficient coupler to silica microspheres. 6 More recently, we have shown that they can effectively probe the spatial and spectral properties of small mode volume ͑V eff ͒, high refractive index semiconductor cavities. 7 Other researchers have proposed 8,9 and realized their use as a collection tool for spontaneous emission from atomic vapors. 10 Here, we show that a fiber taper may be used to channel emission from single selfassembled QDs embedded in a semiconductor slab directly into a standard single-mode fiber with high efficiency ͑ϳ0.1% ͒, and to provide submicron spatial resolution of QDs.The QDs we study consist of a single layer of InAs QDs embedded in an In 0.15 Ga 0.85 As quantum well, a so-called dotin-a-well ͑DWELL͒ structure. 11 The DWELL layer is grown in the center of a GaAs waveguide ͑total waveguide thickness of 256 nm͒, which sits atop a 1.5 m thick Al 0.7 Ga 0.3 As buffer layer. The resulting peak of the ground state emission of the ensemble of QDs is located at = 1.35 m at room temperature. To limit the number of optically pumped QDs, microdisk cavities of diameter D =2 m were fabricated using electron beam lithography and a series of dry and wet etching steps. 12 Although the QDs physically reside in a microcavity, they are nonresonant with the cavity whispering gallery modes ͑WGMs͒. In other words, our primary interest here is general single QD spectroscopy through the fiber taper, without enhancement through interaction with the high quality factor ͑Q͒ microdisk WGMs. The samples were mounted in a continuous-flow liquid He cryostat that has been modified to allow sample probing with optical fiber tapers while being held at cryogenic temperatures ͑T ϳ 14 K͒, as described in detail in Ref. 13. The cryostat setup provides any combination of free-space and fiber taper pumping and collection ͓see Fig. 1͑a͒ for details͔.The inset of Fig. 1͑b͒ shows the emission spectrum from an ensemble of QDs in one of the microdisks. Here, the device is optically pumped through an objective lens at normal incidence ͑free-space pumping͒, with a spot size of 3 m and wa...

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Multiexciton Spectroscopy of a Single Self-Assembled Quantum Dot

Cited by 337 publications

References 21 publications

Self-Assembled InGaAs Quantum Dot Clusters with Controlled Spatial and Spectral Properties

Self-Assembled InGaAs Quantum Dot Clusters with Controlled Spatial and Spectral Properties

Effects of few-particle interaction on the atomiclike levels of a single strain-induced quantum dot

Single quantum dot spectroscopy using a fiber taper waveguide near-field optic

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