Ultranarrow Luminescence Lines from Single Quantum Dots

Grundmann, Marius; Christen, J.; Ledentsov, N. N.; Böhrer, J.; Bimberg, D.; Ruvimov, S.; Werner, P.; Richter, Uwe; Gösele, U.; Heydenreich, J.; Ustinov, V. M.; Egorov, A. Yu.; Zhukov, A. E.; Kop’ev, P. S.; Alfërov, Zh. I.

doi:10.1103/physrevlett.74.4043

Cited by 730 publications

(314 citation statements)

References 18 publications

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“…Three-dimensional (3D) con®nement of excitons at 2D nano-islands must produce an atom-like energy spectrum of excitons [35] leading to the appearance of discrete energy levels of QDs. In the case of a very dense array of QDs, e.g.…”

Section: Emission Of Individual Qdsmentioning

confidence: 99%

Quantum dots formed by ultrathin insertions in wide-gap matrices

et al. 2000

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We report on experimental and theoretical studies on a new type of quantum-dot (QD) structures obtained using ultrathin, i.e. below the critical thickness for 2D±3D transition, strained narrow gap insertions in wide bandgap matrices. We concentrate on submonolayer (SML) or slightly above 1 ML CdSe insertions in a wide-gap II±VI matrices and give the ®rst results on ultrathin InGaN insertions in a GaN matrix. A discussion on detailed comparison of our original results with the results of other authors is presented. The formation of dense arrays (up to 10 12 cm 22 ) of nanoscale two-dimensional (2D) islands is revealed in processed high-resolution transmission electron microscopy images. In the case of stacked sheets of SML insertions, the islands in the neighboring sheets are formed predominantly in correlated or anticorrelated way for thinner and thicker spacer layers, respectively. Different polarization of photoluminescence (PL) emission recorded in edge geometry for vertically-uncoupled and coupled QDs con®rms the QD nature of excitons. By monitoring of sharp lines due to single QDs using cathodoluminescence the 3D con®nement is manifested. We demonstrate signi®cant squeezing of the QD exciton wavefunction in the lateral direction using magneto-optical experiments. We point to complete suppression of lateral motion of excitons bound to islands in case of wide-gap (ZnMgSSe) matrices, as follows from PL excitation studies. A resonant (0-phonon) lasing is observed in ultrathin CdSe insertions and proves the lifting of the k-selection rule for QD excitons. We show that lack of exciton screening in QDs up to high excitation densities enables strong resonant modulation of the refractive index in stacked ultrathin insertions and allows realization of resonant (excitonic) waveguiding and lasing. This enables the realization of a new type of heterostructure laser operating without external optical con®nement by layers having lower average refractive indices. Ultrahigh QD excitonic gain in dense arrays of stacked QDs allows a new type of surface-emitting laser. q 2000 Elsevier Science S.A. All rights reserved.

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Section: Emission Of Individual Qdsmentioning

confidence: 99%

Quantum dots formed by ultrathin insertions in wide-gap matrices

et al. 2000

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“…Recent progress in nanofabrication technology allows the simulation of novel atomic physical phenomena on an artificial platform, such as presence of δ-function-like density of states on quantum dots (QD) 1,2 , realization of molecularorbital state on spatially coupled QDs 3,4 , and formation of nanometer-sized quantum rings 5,6,7,8 , which are nanoscopic analogues of benzene. Among them, fabrication of semiconductor quantum rings has triggered strong interest in realization of quantum topological phenomena, which are expected in a small systems with simply-connected geometry 9,10 .…”

Section: Introductionmentioning

confidence: 99%

Optical transitions in quantum ring complexes

et al. 2005

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Making use of a droplet-epitaxial technique, we realize nanometer-sized quantum ring complexes, consisting of a well-defined inner ring and an outer ring. Electronic structure inherent in the unique quantum system is analyzed using a micro-photoluminescence technique. One advantage of our growth method is that it presents the possibility of varying the ring geometry. Two samples are prepared and studied: a single-wall ring and a concentric double-ring. For both samples, highly efficient photoluminescence emitted from a single quantum structure is detected. The spectra show discrete resonance lines, which reflect the quantized nature of the ringtype electronic states. In the concentric double-ring, the carrier confinement in the inner ring and that in the outer ring are identified distinctly as split lines. The observed spectra are interpreted on the basis of single electron effective mass calculations.

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“…[1][2][3] The optical properties of such islands have been mainly studied by incoherent methods. [4][5][6][7] Driven by the search for blue-green-emitting semiconductor materials, the fabrication [8][9][10][11][12][13] and optical characterization [14][15][16][17][18] of self-assembled II-VI islands have recently been the subject of intensive research. Only little is known about the coherent properties of these structures, giving information about exciton scattering and biexciton formation.…”

mentioning

confidence: 99%