Height stabilization of GaSb/GaAs quantum dots by Al-rich capping

Smakman, EP Erwin; DeJarld, Matt; Luengo-Kovac, Marta; Martin, AJ; Sih, Vanessa; Koenraad, PM Paul; Millunchick, Joanna Mirecki

doi:10.1063/1.4895783

Cited by 9 publications

(5 citation statements)

References 22 publications

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“…Recently, Smakman et al investigated the defect formation in GaSb/ GaAs QDs with cross-sectional scanning tunneling microscopy. 39) They fabricated GaSb QDs on GaAs and capped them with GaAs, AlAs, or AlGaAs, where the QD height and concentration were 4 « 1 nm and 5 © 10 10 cm ¹2 , respec- tively. They found that the strain in GaSb/GaAs QDs caused many structural defects around the QD, and the defects extended into the capping layer as stacking faults.…”

Section: Discussionmentioning

confidence: 99%

“…The defects were present in 11% of the QDs for GaAs capping, 9-17% of the QDs for AlAs capping, and 22% of the QDs for AlGaAs capping. The defect rate will be reduced for smaller QDs 39) or by annealing processes. 40) The effects of these defects should be considered in the calculation to perform a quantitative evaluation, although our model qualitatively describes GaSb/GaAs QD systems with a relatively low defect rate.…”

Section: Discussionmentioning

confidence: 99%

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Electric states in laterally and vertically arrayed type-II quantum dots

Kawazu¹

2015

Jpn. J. Appl. Phys.

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Laterally and vertically arrayed GaSb type-II quantum dots (QDs) in GaAs are studied theoretically to clarify how the electronic states are affected by the QD arrangements. We numerically calculate the wave functions of the electron Ψ e and hole Ψ h and their overlap integral Θ in laterally and vertically arrayed GaSb type-II QDs. It is found that Ψ e is strongly modified by the QD arrangements, resulting in the increase of Θ; the maximum values of Θ for the laterally and vertically arrayed QDs are about two and six times larger than that for the single QD.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Electric states in laterally and vertically arrayed type-II quantum dots

Kawazu¹

2015

Jpn. J. Appl. Phys.

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“…The critical thickness or critical strain is a function of composition of the epitaxial layer. The strain relaxation can also lead to the formation of crystal defects, which strongly affect the optoelectronic properties of the QDs [ 30 , 31 , 32 , 33 ]. Developments in the growth techniques such as MBE or MOVPE in combination with decades of growth optimization made it possible to realize (nearly) defect free QDs.…”

Section: Self-assembled Iii-v Semiconductor Quantum Dotsmentioning

confidence: 99%

“…The size control of DEQDs can also be obtained through engineering the capping layer. This method of optimizing QDs structure was first demonstrated in strained SKQDs, by changing capping layer composition [ 31 , 98 , 99 , 100 ], capping rate [ 101 ], strain field [ 20 ], adding growth interruptions and annealing steps [ 102 , 103 ]. Such a capping process (flushing technique) can be applied to GaAs/AlGaAs DEQDs to obtain a precise control over QDs height.…”

Section: Strain-free Gaas/algaas Deqdsmentioning

confidence: 99%

Atomic-Scale Characterization of Droplet Epitaxy Quantum Dots

Gajjela

Koenraad

2021

Nanomaterials

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The fundamental understanding of quantum dot (QD) growth mechanism is essential to improve QD based optoelectronic devices. The size, shape, composition, and density of the QDs strongly influence the optoelectronic properties of the QDs. In this article, we present a detailed review on atomic-scale characterization of droplet epitaxy quantum dots by cross-sectional scanning tunneling microscopy (X-STM) and atom probe tomography (APT). We will discuss both strain-free GaAs/AlGaAs QDs and strained InAs/InP QDs grown by droplet epitaxy. The effects of various growth conditions on morphology and composition are presented. The efficiency of methods such as flushing technique is shown by comparing with conventional droplet epitaxy QDs to further gain control over QD height. A detailed characterization of etch pits in both QD systems is provided by X-STM and APT. This review presents an overview of detailed structural and compositional analysis that have assisted in improving the fabrication of QD based optoelectronic devices grown by droplet epitaxy.

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“…is has been attributed to crystal defects at the QDs' bases, which lead to mismatch dislocations, which dislocate the whole QDs by 1 ML [19]. e resulting stress/strain cannot relax, especially in the case of Al-rich surrounding material.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial Growth of Optoelectronically Active Ga(As)Sb Quantum Dots on Al‐Rich AlGaAs with GaAs Capsule Layers

Strassner

Richter

Loeber

et al. 2021

Advances in Materials Science and Engineering

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We present a study of optoelectronically active Ga(As)As quantum dots (QDs) on Al-rich AlxGa1-xAs layers with Al concentrations up to x = 90%. So far, however, it has not been possible to grow optoelectronically active Ga(As)As QDs epitaxially directly on and in between Al-rich barrier layers in the AlGaInAsSb material system. A QD morphology might appear on the growth front, but the QD-like entities will not luminesce. Here, we use photoluminescence (PL) measurements to show that thin Al-free capsule layers between Al-rich barrier layers and the QD layers can solve this problem; this way, the QDs become optoelectronically active; that is, the dots become QDs. We consider antimonide QDs, that is, Ga(As)Sb QDs, either on GaAs for comparison or on AlxGa1-xAs barriers (x >10%) with GaAs capsule layers in between. We also discuss the influence of QD coupling both due to stress/strain from neighboring QDs and quantum-mechanically on the wavelength of the photoluminescence peak. Due to their mere existence, the capsule layers alter the barriers by becoming part of them. Quantum dots applications such as QD semiconductor lasers for spectroscopy or QDs as binary storage cells will profit from this additional degree of design freedom.

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Height stabilization of GaSb/GaAs quantum dots by Al-rich capping

Cited by 9 publications

References 22 publications

Electric states in laterally and vertically arrayed type-II quantum dots

Electric states in laterally and vertically arrayed type-II quantum dots

Atomic-Scale Characterization of Droplet Epitaxy Quantum Dots

Epitaxial Growth of Optoelectronically Active Ga(As)Sb Quantum Dots on Al‐Rich AlGaAs with GaAs Capsule Layers

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