General route for the decomposition of InAs quantum dots during the capping process

González, David; Reyes, Daniel; Utrilla, A. D.; Ben, T.; Braza, V.; Guzmán, Á.; Hierro, A.; Ulloa, J. M.

doi:10.1088/0957-4484/27/12/125703

Cited by 23 publications

(17 citation statements)

References 39 publications

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“…Two activation-energy components are apparent. The first component of approximately 20 meV corresponds to the energy difference between the QD ESs based on the three-dimensional quantum simulations, where the QD diameter determined by AFM analysis [44] and the nonuniform In composition inside the QD [45] are taken into account (see the Supplemental Material [35]); these simulations are performed using the nextnano commercial software [46]. Thermal excitation of the electrons induced PL quenching due to the decrease in the radiative recombination efficiency, which is attributed to the weakened overlap of the electron and hole wave functions.…”

Section: Resultsmentioning

confidence: 99%

Highly Efficient Room-Temperature Electron-Photon Spin Conversion Using a Semiconductor Hybrid Nanosystem with Gradual Quantum Dimensionality Reduction

et al. 2020

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Improved electron-photon spin conversion efficiency is a key component of technological platforms for optospintronics integration in information processing; this concept is based on optical devices transmitting and receiving spin information superimposed on light. Semiconductor quantum dots (QDs) are the most promising materials for optospintronic devices; however, in addition to their weak room-temperature luminescence, their electron-photon spin conversion efficiencies are lower than 50%. Here, we present semiconductor QDs embedded in quantum wells (QWs) containing quasi-QDs. The proposed semiconductor hybrid nanosystem with gradual quantum dimensionality reduction demonstrates luminescence one order of magnitude stronger than that of conventional QDs and an electron-photon spin conversion efficiency of almost 80% at room temperature. Optical characterization reveals that efficient carrier capture, suppressed depolarized-spin reinjection, and quasi-three-dimensional quantum confinements in the QWs facilitate the highly efficient electron-photon spin conversion. This study constitutes a significant advance towards the realization of QD-based spin-functional optical devices for electron-spin-based quantum information platforms.

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Section: Resultsmentioning

confidence: 99%

Highly Efficient Room-Temperature Electron-Photon Spin Conversion Using a Semiconductor Hybrid Nanosystem with Gradual Quantum Dimensionality Reduction

et al. 2020

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“…Thus, the WL of the CL5 layer only keeps an amount of In equivalent to 1.1 MLs of InAs compared to the initial 2.8 MLs deposited. Remarkably, this reduction of the WL is stronger than in other capping strategies such as the use of strain-reducing layers (SRL) or increased GaAs CL growth rate [34,50]. On the one hand, the amount of InAs in the WL after accelerating the growth rate of the GaAs CL to 2 ML/s is 1.7 MLs of InAs, but no substantial improvement is expected for faster growth [46,51].…”

Section: Wl Reductionmentioning

confidence: 98%

Suppressing the Effect of the Wetting Layer through AlAs Capping in InAs/GaAs QD Structures for Solar Cells Applications

et al. 2022

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Recently, thin AlAs capping layers (CLs) on InAs quantum dot solar cells (QDSCs) have been shown to yield better photovoltaic efficiency compared to traditional QDSCs. Although it has been proposed that this improvement is due to the suppression of the capture of photogenerated carriers through the wetting layer (WL) states by a de-wetting process, the mechanisms that operate during this process are not clear. In this work, a structural analysis of the WL characteristics in the AlAs/InAs QD system with different CL-thickness has been made by scanning transmission electron microscopy techniques. First, an exponential decline of the amount of InAs in the WL with the CL thickness increase has been found, far from a complete elimination of the WL. Instead, this reduction is linked to a higher shield effect against QD decomposition. Second, there is no compositional separation between the WL and CL, but rather single layer with a variable content of InAlGaAs. Both effects, the high intermixing and WL reduction cause a drastic change in electronic levels, with the CL making up of 1–2 monolayers being the most effective configuration to reduce the radiative-recombination and minimize the potential barriers for carrier transport.

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“…Since for this growth rate the decomposition process is completely suppressed, this should be the thinnest WL layer achievable with our approach. The effect of the GaAs capping rate on the WL morphology has been recently confirmed by other techniques [8], [15]. A thinner WL should result in larger confinement energy and, therefore, reduced potential barriers for electrons and holes.…”

Section: Effect Of Capping Rate On Wl Thicknessmentioning

confidence: 69%

Effect of capping rate on InAs/GaAs quantum dot solar cells

Stanojevic

Gonzalo

Utrilla

et al. 2019

Physics, Simulation, and Photonic Engineering of Photovoltaic Devices VIII

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The unavoidable presence of the wetting layer (WL) in Stranski-Krastanov quantum dots (QD) has typically a negative impact on the performance of QD solar cells. In this work, a simple method to engineer the WL of InAs/GaAs QD solar cells is investigated. In particular, we show that covering the QDs at high GaAs capping rates reduces In-Ga intermixing and, therefore, In redistribution from the QDs to the WL. This results not only in larger QDs, but also in thinner WLs, with larger quantum confinement energies and reduced potential barriers for electrons and holes. Carrier trapping by the WLs and subsequent recombination is therefore reduced, resulting in larger photocurrent values of the QD solar cells under short circuit conditions.

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General route for the decomposition of InAs quantum dots during the capping process

Cited by 23 publications

References 39 publications

Highly Efficient Room-Temperature Electron-Photon Spin Conversion Using a Semiconductor Hybrid Nanosystem with Gradual Quantum Dimensionality Reduction

Highly Efficient Room-Temperature Electron-Photon Spin Conversion Using a Semiconductor Hybrid Nanosystem with Gradual Quantum Dimensionality Reduction

Suppressing the Effect of the Wetting Layer through AlAs Capping in InAs/GaAs QD Structures for Solar Cells Applications

Effect of capping rate on InAs/GaAs quantum dot solar cells

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