Optical study of segregation effects on the electronic properties of molecular-beam-epitaxy grown (In,Ga)As/GaAs quantum wells

Disseix, P.; Leymarie, J.; Vasson, A.; Monier, C.; Grandjean, N.; Leroux, M.; Massies, J.

doi:10.1103/physrevb.55.2406

Cited by 36 publications

(18 citation statements)

References 34 publications

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“…As it has been shown previously, the strained conduction band offset ratio for Ga 1-x In x As/ GaAs material system depends rather weakly on the In content for compositions with x ≥ 0.1 and equals to about 0.6 (which is equivalent to approx. 0.8 of the unstrained one for our composition range) [8]. On the other hand, it has been demonstrated theoretically and experimentally that the unstrained conduction band offset ratio for a www.pss-c.com pure InAs/GaAs heterointerface falls into the range between 83 and 92 % [8,9].…”

Section: Methodsmentioning

confidence: 89%

“…0.8 of the unstrained one for our composition range) [8]. On the other hand, it has been demonstrated theoretically and experimentally that the unstrained conduction band offset ratio for a www.pss-c.com pure InAs/GaAs heterointerface falls into the range between 83 and 92 % [8,9]. Therefore, we performed our calculations only for several Q C values around 80 %.…”

Section: Methodsmentioning

confidence: 91%

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Optical characteristics of lowly strained GaInAs quantum dots

Löffler

Poloczek

Sęk

et al. 2006

Phys. Status Solidi (c)

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We have investigated the optical properties of lowly strained GaInAs quantum dots (QDs). The structures were grown for a constant nominal GaInAs layer thickness but varying content (strain) from below to far above the critical thickness conditions. In order to investigate the properties of such an uncommon QD system, photoreflectance (PR) and photoluminescence, combined with scanning electron microscopy, have been used. Optical transitions connected with the ternary layer have been observed and followed from the lowest content quantum well case through the transformation into 3D islands on the wetting layer (WL) and a coexistence of the QD-related and WL-related transitions. Due to the observation of both heavy hole and light hole related transitions in PR spectra, the thickness of the wetting layer versus changed indium content could be determined by comparing the experimental data with the results of the effective mass envelope function calculations.1 Introduction Self-assembled semiconductor quantum dots (QDs) have attracted considerable interest during recent years. Many important fundamental properties related to three-dimensional carrier confinement, delta-like density of states and atom-like properties have been discussed in the literature and a lot of practical applications have been proposed. Independently of the material system used, the selfassembled QD growth is driven by a very large lattice mismatch between the QD layer and the substrate, typically causing a formation of 3D islands on a thin 2D layer (called wetting layer), a process known as the Stranski-Krastanov growth mode. When the strain is reduced by decreasing the In content in the deposited layer, it becomes difficult to self-create 3D islands in favour of planar 2D growth. On the other hand, such structures offer many new properties and many possible applications mainly driven by the QD shape engineering. Therefore, this kind of growth has been a challenge for semiconductor technology in the last years and it has already been demonstrated in different material systems, including GaInAs on GaAs [1, 2]. As it has been shown, such lowly strained GaInAs QDs have distinguishably different properties than the standard ones, like for instance strong shape asymmetry, low surface density and large sizes [2,3]. All those properties can be interesting from the application point of view. Low dot densities are usually necessary in all the quantum cryptography and quantum computing applications [4], whereas large dot volumes inducing enhanced exciton oscillator strength are necessary to increase the strength of light-matter interaction between the QD excitons and photons confined in resonant cavities [5], which has been already confirmed experimentally for the case of low content and large Ga 0.7 In 0.3 As/GaAs dots in pillar microcavities [3]. Our studies focus on the optical properties of lowly strained GaInAs QD structures (i.e. in the composition range of 30 % indium and about 2 % layer/substrate lattice mismatch), which are barely known yet.

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Section: Methodsmentioning

confidence: 89%

Section: Methodsmentioning

confidence: 91%

Optical characteristics of lowly strained GaInAs quantum dots

Löffler

Poloczek

Sęk

et al. 2006

Phys. Status Solidi (c)

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“…The best agreement between the experiment and calculation has been obtained for the WL thickness of about 1.6 monolayer and the band offset in the conduction band ͑Q C ͒ of about 87% ͑Q C taken for the unstrained materials, i.e., the so-called chemical band offset which corresponds to about 65% of the band offset in the real strained structure͒, which are reasonable values when compared to those cited in the literature. [17][18][19][26][27][28] In the real case, one would expect some intermixing of the WL QW due to the possible In-Ga atom exchange during growth or some interdiffusion. In general, these processes should modify the confinement potential significantly and also shift the optical transition energies.…”

Section: Resultsmentioning

confidence: 99%

Wetting layer states of InAs∕GaAs self-assembled quantum dot structures: Effect of intermixing and capping layer

Sęk

Ryczko

Motyka

et al. 2007

Journal of Applied Physics

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's 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 publicationCitation for published version (APA): Sek, G., Ryczko, K., Motyka, M., Andrzejewski, J., Wysocka, K., Misiewicz, J., ... Patriarche, G. (2007). Wetting layer states of InAs/GaAs self-assembled quantum dot structures. Effect of intermixing and capping layer. Journal of Applied Physics, 101(6), 063539-1/7. [063539]. DOI: 10.1063/1.2711146 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 ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The authors present a modulated reflectivity study of the wetting layer ͑WL͒ states in molecular beam epitaxy grown InAs/ GaAs quantum dot ͑QD͒ structures designed to emit light in the 1.3-1.5 m range. A high sensitivity of the technique has allowed the observation of all optical transitions in the QD system, including low oscillator strength transitions related to QD ground and excited states, and the ones connected with the WL quantum well ͑QW͒. The support of WL content profiles, determined by transmission electron microscopy, has made it possible to analyze in detail the real WL QW confinement potential which was then used for calculating the optical transition energies. We could conclude that in spite of a very effective WL QW intermixing, mainly due to the Ga-In exchange process ͑causing the reduction of the maximum indium content in the WL layer to about 35% from nominally deposited InAs͒, the transition energies remain almost unaffected. The latter effect could be explained in effective mass envelope function calculations taking into account the intermixing of the QW interfaces described within the diffusion model. We have followed the WL-...

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“…The number of points in the mesh should be enough to eliminate the error due to substitution of the derivative with the finite-difference approximation (12). We compared the results of numerical solution of (10) by the shooting method with the well known analytical solution for a rectangular quantum well.…”

Section: B Solving the Schrödinger Equationmentioning

confidence: 99%

“…They conclude that no detailed study has yet been carried out on InGaAs-based heterojunctions. Recent publications on this subject 11,12,13,14 only present partial results for different compositions, more or less agreed with "recommended" in Ref. 9.…”

Section: Introductionmentioning

confidence: 99%

Determination of band offsets in strainedInxGa1−xAs∕GaAsquantum

et al. 2004

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The results of measurements and numerical simulation of charge carrier distribution and energy states in strained quantum wells InxGa1−xAs/GaAs (0.06 x 0.29) by C-V-profiling are presented. Precise values of conduction band offsets for these pseudomorphic QWs have been obtained by means of self-consistent solution of Schrödinger and Poisson equations and following fitting to experimental data. For the conduction band offsets in strained InxGa1−xAs/GaAs -QWs the expression ∆EC(x) = 0.814x − 0.21x 2 has been obtained.

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Optical study of segregation effects on the electronic properties of molecular-beam-epitaxy grown (In,Ga)As/GaAs quantum wells

Cited by 36 publications

References 34 publications

Optical characteristics of lowly strained GaInAs quantum dots

Optical characteristics of lowly strained GaInAs quantum dots

Wetting layer states of InAs∕GaAs self-assembled quantum dot structures: Effect of intermixing and capping layer

Determination of band offsets in strainedInxGa1−xAs∕GaAsquantum

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