Direct formation of vertically coupled quantum dots in Stranski-Krastanow growth

Ledentsov, N. N.; Shchukin, V. A.; Grundmann, Marius; Kirstaedter, N.; Böhrer, J.; Schmidt, Oliver G.; Bimberg, D.; Ustinov, V. M.; Egorov, A. Yu.; Zhukov, A. E.; Kop’ev, P. S.; Zaı̆tsev, S. V.; Gordeev, N. Yu.; Alfërov, Zh. I.; Боровков, А. И.; Kosogov, A. O.; Ruvimov, S.; Werner, P.; Gösele, U.; Heydenreich, J.

doi:10.1103/physrevb.54.8743

Cited by 510 publications

(228 citation statements)

References 31 publications

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“…[1][2][3][4][5][6] The development of such structures followed the exploitation of the threedimensional confinement in self-assembled InAs/GaAs Stranski-Krastanow islands and has demonstrated low threshold current and reduced temperature-dependent lasing characteristics. In order to increase the emission wavelength of InAs/GaAs QDs to the telecommunication range ͑1.31-1.55 m͒, the QD layers needed to be formed as substantially larger islands compared to the first generation of QD laser devices.…”

Section: Role Of Segregation In Inas/gaas Quantum Dot Structures Cappmentioning

confidence: 99%

“…In order to increase the emission wavelength of InAs/GaAs QDs to the telecommunication range ͑1.31-1.55 m͒, the QD layers needed to be formed as substantially larger islands compared to the first generation of QD laser devices. 1,2 Large QDs can be directly synthesized by overgrowth ͑i.e., supplying material well beyond the onset of nucleation͒, 7 by controlling the epitaxial growth conditions 8,9 or by growing on higher-index surfaces. 10,11 Metamorphic buffer layers have been used to this effect.…”

Section: Role Of Segregation In Inas/gaas Quantum Dot Structures Cappmentioning

confidence: 99%

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Role of segregation in InAs/GaAs quantum dot structures capped with a GaAsSb strain-reduction layer

et al. 2009

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Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement: We report a combined experimental and theoretical analysis of Sb and In segregation during the epitaxial growth of InAs self-assembled quantum dot structures covered with a GaSbAs strain-reducing capping layer. Cross-sectional scanning tunneling microscopy shows strong Sb and In segregation which extends through the GaAsSb and into the GaAs matrix. We compare various existing models used to describe the exchange of group III and V atoms in semiconductors and conclude that commonly used methods that only consider segregation between two adjacent monolayers are insufficient to describe the experimental observations. We show that a three-layer model originally proposed for the SiGe system ͓D. J. Godbey and M. G. Ancona, J. Vac. Sci. Technol. A 15, 976 ͑1997͔͒ is instead capable of correctly describing the extended diffusion of both In and Sb atoms. Using atomistic modeling, we present strain maps of the quantum dot structures that show the propagation of the strain into the GaAs region is strongly affected by the shape and composition of the strain-reduction layer.

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Section: Role Of Segregation In Inas/gaas Quantum Dot Structures Cappmentioning

confidence: 99%

Section: Role Of Segregation In Inas/gaas Quantum Dot Structures Cappmentioning

confidence: 99%

Role of segregation in InAs/GaAs quantum dot structures capped with a GaAsSb strain-reduction layer

et al. 2009

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“…[7][8][9][10][11] In a VQDM, two or more adjacent dots separated by thin barrier(s) are stacked one by one along the growth axis. 12 Using wellestablished epitaxial growth protocols, geometrical properties such as height, barrier thickness, and relative position of the QDs can all be precisely controlled. By applying an electric field along the growth axis, the energy levels of the QDs can be simultaneously tuned relative to one another and to a doped substrate.…”

Section: Introductionmentioning

confidence: 99%

Coulomb interaction signatures in self-assembled lateral quantum dot molecules

et al. 2013

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We use photoluminescence spectroscopy to investigate the ground state of single self-assembled InGaAs lateral quantum dot molecules. We apply a voltage along the growth direction that allows us to control the total charge occupancy of the quantum dot molecule. Using a combination of computational modeling and experimental analysis, we assign the observed discrete spectral lines to specific charge distributions. We explain the dynamic processes that lead to these charge configurations through electrical injection and optical generation. Our systemic analysis provides evidence of interdot tunneling of electrons as predicted in previous theoretical work.

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“…This large increase cannot be explained just by the superposition of three independent QD layers, thus it may be due to a decreased exciton lifetime reported in vertically coupled QD stacks [17] leading to a relatively higher PL intensity. For QD stacks, it is further reported that the QD size slowly increases layer by layer, leading to an overall redshift of the QD PL [18] as seen in Fig.…”

Section: Resultsmentioning

confidence: 94%

Optical properties and modal gain of InGaN quantum dot stacks

Kalden

Sebald

Gutowski

et al. 2009

Phys. Status Solidi (c)

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We present investigations of the optical properties of stacked InGaN quantum dot layers and demonstrate their advantage over single quantum dot layer structures. Measurements were performed on structures containing a single layer with quantum dots or threefold stacked quantum dot layers, respectively. A superlinear increase of the quantum dot related photoluminescence is detected with increasing number of quantum dot layers while other relevant GaN related spectral features are much less intensive when compared to the photoluminescence of a single quantum dot layer. The quantum dot character of the active material is verified by microphotoluminescence experiments at different temperatures. For the possible integration within optical devices in the future the threshold power density was investigated as well as the modal gain by using the variable stripe length method. As the threshold is 670 kW/cm 2 at 13 K, the modal gain maximum is at 50 cm -1 . In contrast to these limited total values, the modal gain per quantum dot is as high as 10 -9 cm -1 , being comparable to the II-VI and III-As compounds. These results are a promising first step towards bright low threshold InGaN quantum dot based light emitting devices in the near future.

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Direct formation of vertically coupled quantum dots in Stranski-Krastanow growth

Cited by 510 publications

References 31 publications

Role of segregation in InAs/GaAs quantum dot structures capped with a GaAsSb strain-reduction layer

Role of segregation in InAs/GaAs quantum dot structures capped with a GaAsSb strain-reduction layer

Coulomb interaction signatures in self-assembled lateral quantum dot molecules

Optical properties and modal gain of InGaN quantum dot stacks

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