Room temperature emission at 1.6μm from InGaAs quantum dots capped with GaAsSb

Ripalda, J. M.; Granados, Daniel; González, Y.; Sánchez, Ana; Molina, S. I.; García, J. M.

doi:10.1063/1.2130529

Cited by 111 publications

(89 citation statements)

References 12 publications

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“…39 In fact the observed heights of the QDs are as much as twice compared with QDs capped with pure GaAs. Ripalda et al 40 reported the use of GaAsSb capping to extend the emission wavelength of InGaAs quantum dot structures and observed that a type II alignment takes place when the Sb content of the capping layer is higher than 14%. Furthermore they also report an order of magnitude improvement of the room-temperature luminescence intensity in the 1.3 m spectral range for GaAsSb covered InAs QDs due to increased hole localization.…”

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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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%

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

et al. 2009

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“…The strong red shift observed by using GaAsSb instead of GaAs capping layers has been attributed to a type II band alignment [64,70]. However, the structural properties of these QDs have not been studied, despite the fact that they could be significantly different from those of GaAs-capped QDs.…”

Section: Gaassb Capping Of Inas/gaas Qdsmentioning

confidence: 99%

“…In the last few years, GaAsSb capping layers have also been used to increase the emission wavelength of InAs/GaAs QDs [63,69] and room temperature photoluminescence at 1.6\xm has recently been reported from GaAsSb-capped In(Ga)As/GaAs QDs [64,70]. The strong red shift observed by using GaAsSb instead of GaAs capping layers has been attributed to a type II band alignment [64,70].…”

Section: Gaassb Capping Of Inas/gaas Qdsmentioning

confidence: 99%

“…Since GaAs is the most commonly used capping material for InAs/GaAs QDs, the existing structural studies of buried InAs/GaAs QDs have been mainly devoted to GaAs-capped QDs. Nevertheless, different materials such as InGaAs and GaAsSb are nowadays used to cap InAs/GaAs QDs in an effort to extend its emission wavelength to the technologically interesting 1.3-155 \xm region [59][60][61][62][63][64]. For InAs/ InP QDs, capping materials other than InP, like InGaAsP, have also successfully been used for laser applications [65][66][67].…”

Section: Capping With Different Materialsmentioning

confidence: 99%

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InAs Quantum Dot Formation Studied at the Atomic Scale by Cross-sectional Scanning Tunnelling Microscopy

Ulloa

Offermans

Koenraad

2008

Handbook of Self Assembled Semiconductor Nanostructures for Novel Devices in Photonics and Electronics

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Introduction Quantum dot formationSelf-assembled quantum dots (QDs) have attracted much attention in the last years [1,2]. These nanostructures are very interesting from a scientific point of view because they form nearly ideal zero-dimensional systems in which quantum confinement effects become very important. These unique properties also make them very interesting from a technological point of view. For example, InAs QDs are employed in QD lasers [3,4], single electron transistors [5], midinfrared detectors [6,7], single-photon sources [8,9], etc. InAs QDs are commonly created by the Stranski-Krastanov growth mode when InAs is deposited on a substrate with a bigger lattice constant, like GaAs or InP [10]. Above a certain critical thickness of InAs, three-dimensional islands are spontaneously formed on top of a wetting layer (WL) to reduce the strain energy. Once created, the QDs are subsequently capped, a step which is required for any device application.For any application based on InAs QDs, an accurate control of their electronic properties is required. The electron and hole states in the dot are very sensitive to the QD size, shape and composition (as well as to the surrounding material), and therefore an accurate control of the QD structural properties is necessary for applications. This explains the strong effort dedicated in the last years to the structural characterization of QDs [11], which is essential in order to have a deep understanding of the QD formation process. Although a lot of effort has been dedicated to study surface QDs, there are relatively few studies focused on the effect of the capping process [12][13][14][15][16][17][18][19][20]. Some of these studies have already shown significant differences in size, shape and composition between uncapped and capped QDs. For example, an important collapse of the QD height has been reported for InAs/GaAs QDs capped with GaAs [14,15,[17][18][19], revealing the big influence of the capping process on the structural properties of the QDs. Indeed, critical issues affecting the dot take place during capping like dot decomposition, intermixing, segregation, As/P exchange and composition modulation in the capping layer. This means that the real buried QDs must be studied in order to understand the complete QD formation process. Cross-sectional scanning tunnelling microscopy is an especially useful technique for this purpose, because it allows the structure of the capped dots at the atomic scale to be assessed. Cross-sectional scanning tunnelling microscopy (X-STM)The scanning tunnelling microscope is part of the family of scanning probe microscopes, which are able to provide direct real space information of a physical property at the atomic scale. This

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“…This capping layer leads to QD emission at 1.62 μm at RT. 12 This redshift was related with a type-I to type-II transition of the system energy levels with the hole deeply confined in the QD and the electron wave function delocalized in the capping quantum well (QW). Liu et al have quantified the concentration of Sb that leads to such type-I to type-II transitions-14%-in similar structures capped with a GaAs 1−x Sb x QW.…”

Section: Introductionmentioning

confidence: 99%

Effect of Sb incorporation on the electronic structure of InAs quantum dots

Taboada¹,

Llorens²,

Alonso-Álvarez³

et al. 2013

Phys. Rev. B

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On the basis of optical characterization experiments and an eight band kp model, we have studied the effect of Sb incorporation on the electronic structure of InAs quantum dots (QDs). We have found that Sb incorporation in InAs QDs shifts the hole wave function to the center of the QD from the edges of the QD where it is otherwise pinned down by the effects of shear stress. The observed changes in the ground-state energy cannot merely be explained by a composition change upon Sb exposure but can be accounted for when the change in lateral size is taken into consideration. The Sb distribution inside the QDs produces distinctive changes in the density of states, particularly, in the separation between excitation shells. We find a 50% increase in the thermal escape activation energy compared with reference InAs quantum dots as well as an increment of the fundamental transition decay time with Sb incorporation. Furthermore, we find that Sb incorporation into quantum dots is strongly nonlinear with coverage, saturating at low doses. This suggests the existence of a solubility limit of the Sb incorporation into the quantum dots during growth.

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Room temperature emission at 1.6μm from InGaAs quantum dots capped with GaAsSb

Cited by 111 publications

References 12 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

InAs Quantum Dot Formation Studied at the Atomic Scale by Cross-sectional Scanning Tunnelling Microscopy

Effect of Sb incorporation on the electronic structure of InAs quantum dots

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