Suppression of photoluminescence from wetting layer of InAs quantum dots grown on (311)B GaAs with AlAs cap

Lu, Xiangmeng; Matsubara, Satοshi; Nakagawa, Yasuaki; Kitada, Takahiro; Isu, Toshiro

doi:10.1016/j.jcrysgro.2015.02.074

Cited by 6 publications

(3 citation statements)

References 20 publications

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“…Recently, the use of thin AlAs capping layers (CLs) on InAs QDs has attracted special attention since important improvements [18,19] or even a complete recovery [14] of the V OC in these QDSCs have been reported. It has been proposed that the cause of this improvement is the elimination of the In(Ga)As WL due to phase separation [20,21]. This hypothesis comes from earlier studies by Tsatsul'nikov et al [22] using cross-sectional transmission electron microscopy (TEM) imaging.…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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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“…The spectra consist of two peaks. The one with a shorter wavelength can be attributed to the emission from the InGaN WL, while the other peak with a longer wavelength is attributed to the emission from the InGaN QDs. − For sample B, an extremely intense peak centering around 430 nm together with one longitudinal-optical phonon replica can be observed at relatively low temperatures (LTs) (below 150 K), which is referred to the luminescence of the QWs. The TDPL spectra reveal that carriers can tunnel from the QW into the QDs when the GaN barrier in the nanostructure is sufficiently thin.…”

Section: Resultsmentioning

confidence: 99%

Abnormal Stranski–Krastanov Mode Growth of Green InGaN Quantum Dots: Morphology, Optical Properties, and Applications in Light-Emitting Devices

Wang

et al. 2018

ACS Appl. Mater. Interfaces

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Stranski–Krastanov (SK) growth mode is widely adopted for the self-assembled growth of semiconductor quantum dots (QDs), wherein a relatively large critical thickness is essential and a thick wetting layer (WL) is formed beneath the QD layer. In this paper, we report the metal organic vapor phase epitaxy of green InGaN QDs, employing a growth interruption method to decrease the critical thickness and improve the morphology of QDs. The QDs exhibit similar photoluminescence properties with those grown by conventional SK mode, implying the existence of a WL. We experimentally verify that the formation of QDs, whether based on the SK mode or the growth interruption method, conforms to the phase separation theory. However, the density of QDs grown by the interruption method exhibits abnormal dependence on the strain when a quantum well (QW) is inserted beneath the QD layer. Furthermore, the underlying QW not only influences the morphology of the QDs but also plays as a reservoir of electrons, which helps enhance the photoluminescence and the electroluminescence of the QDs. The method of QD growth with improved morphology and luminescence by introducing the QW–QD coupled nanostructure is universally applicable to similar material systems. Furthermore, a 550 nm green light-emitting diode (LED) and a 526 nm superluminescent LED based on the nanostructure are demonstrated.

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“…We show here that the QD-properties can be radically altered when WL-states are absent. Electron WLstates are removed by a simple modification to the SKgrowth: InGaAs QDs are overgrown with a monolayer of AlAs [29][30][31][32] . The absence of electron WL-states for AlAscapped QDs is explained on the nano-scale: AlAs increases the bandgap of the material laterally surrounding a QD thereby eliminating bound electron WL-states.…”

mentioning

confidence: 99%

Excitons in InGaAs quantum dots without electron wetting layer states

et al. 2019

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The Stranski-Krastanov (SK) growth-mode facilitates the self-assembly of quantum dots (QDs) using lattice-mismatched semiconductors, for instance InAs and GaAs. SK QDs are defect-free and can be embedded in heterostructures and nano-engineered devices. InAs QDs are excellent photon emitters: QD-excitons, electron-hole bound pairs, are exploited as emitters of high quality single photons for quantum communication. One significant drawback of the SK-mode is the wetting layer (WL). The WL results in a continuum rather close in energy to the QD-confined-states. The WL-states lead to unwanted scattering and dephasing processes of QD-excitons. Here, we report that a slight modification to the SK-growth-protocol of InAs on GaAs -we add a monolayer of AlAs following InAs QD formation -results in a radical change to the QD-excitons. Extensive characterisation demonstrates that this additional layer eliminates the WL-continuum for electrons enabling the creation of highly charged excitons where up to six electrons occupy the same QD. Single QDs grown with this protocol exhibit optical linewidths matching those of the very best SK QDs making them an attractive alternative to standard InGaAs QDs. arXiv:1810.00891v1 [cond-mat.mes-hall]

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Suppression of photoluminescence from wetting layer of InAs quantum dots grown on (311)B GaAs with AlAs cap

Cited by 6 publications

References 20 publications

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

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

Abnormal Stranski–Krastanov Mode Growth of Green InGaN Quantum Dots: Morphology, Optical Properties, and Applications in Light-Emitting Devices

Excitons in InGaAs quantum dots without electron wetting layer states

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