Excited states in self-organized InAs/GaAs quantum dots: Theory and experiment

Grundmann, Marius; Ledentsov, N. N.; Stier, O.; Bimberg, D.; Ustinov, V. M.; Kop’ev, P. S.; Alfërov, Zh. I.

doi:10.1063/1.116118

Cited by 224 publications

(82 citation statements)

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“…The strong confinement regime is typical for epitaxial QDs due to their sizes in the range of few up to tens of nanometers. The quantized electron (hole) energy level separation for typical indium arsenide QDs is in the range of 50-200 meV (25-150 meV) and 40 meV (25 meV) for InAs/GaAs [3][4][5][6][7] and in the InAs/InP material * Corresponding author: anna.musial@pwr.edu.pl system [8][9][10], respectively, and depends on the QD size. This should be compared to the exciton binding energy for which values in the range of 12-32 meV and 15-33 meV, respectively, have been reported.…”

Section: Introductionmentioning

confidence: 99%

Toward weak confinement regime in epitaxial nanostructures: Interdependence of spatial character of quantum confinement and wave function extension in large and elongated quantum dots

et al. 2014

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In this paper we present a comprehensive and detailed analysis of carrier/exciton wave function extension in large low-strain In 0.3 Ga 0.7 As quantum dots (QDs). They exhibit rather shallow confinement potential with electron/hole localization energy below 30 meV and confinement strength substantially weakened in comparison to typical epitaxial quasi-zero-dimensional semiconductor nanostructures. The aim of this study is to investigate the influence of different factors on the wave function (probability density distribution) for carriers or excitons in this regime, i.e., object shape anisotropy as well as strain, piezoelectricity, and Coulomb interactions, and to identify the physical mechanisms determining the properties of optical emission. To probe the wave function symmetry, polarization-resolved photoluminescence has been performed, and the spatial extensions of the corresponding probability densities have been verified in magneto-optical measurements. The observed diamagnetic coefficients in the range of (15-31) μeV/T 2 reflect large in-plane QD size. These studies also enable us to investigate the importance of light hole states admixture to the valence band ground state in such nanostructures, which can be addressed via the degree of linear polarization of emission as well as the exciton g X factor. The linear-polarization-resolved measurements revealed an exceptionally low exciton fine structure splitting of 5 μeV on average as well as a low emission polarization degree of −0.05, with the polarization perpendicular to the QD elongation direction dominating. The increased light hole contribution to the lowest energy hole level is reflected in the decreased exciton g X factor (in the range of 0-1) and is consistent with the results of the eight-band k·p modelling. Based on the temperature dependence of the diamagnetic coefficient, the problem of individual QD uniformity has additionally been discussed. To evaluate the impact of the confinment potential and the structure geometry on the optical properties of the QDs, a comparison between the investigated dots and InAs/InGaAlAs/InP quantum dashes exhibiting a much deeper confining potential is presented.

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Section: Introductionmentioning

confidence: 99%

Toward weak confinement regime in epitaxial nanostructures: Interdependence of spatial character of quantum confinement and wave function extension in large and elongated quantum dots

et al. 2014

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“…Figure 9 shows that the spectra contain three peaks unlike those of Figs. 5 and 6, and the third peak is due to the second excited state of large-sized QDs grown at greater InAs monolayer coverage [24]. Now it is important to note that with the increase in in situ annealing just after the island deposition is stopped, the peak representing the GS transition in the PL spectrum of the QD samples in Fig.…”

Section: Resultsmentioning

confidence: 99%

A comprehensive study of the effect of in situ annealing at high growth temperature on the morphological and optical properties of self-assembled InAs/GaAs QDs

et al. 2008

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We investigate the effect of in situ annealing during growth pause on the morphological and optical properties of self-assembled InAs/GaAs quantum dots (QDs). The islands were grown at different growth rates and having different monolayer coverage. The results were explained on the basis of atomic force microscopy (AFM) and photo-luminescence (PL) measurements. The studies show the occurrence of ripening-like phenomenon, observed in strained semiconductor system. Agglomeration of the selfassembled QDs takes place during dot pause leading to an equilibrium size distribution. The PL properties of the QDs are affected by the Indium desorption from the surface of the QDs during dot pause annealing at high growth temperature (520°C) subsiding the effect of the narrowing of the dot size distribution with growth pause. The samples having high monolayer coverage (3.4 ML) and grown at a slower growth rate (0.032 ML s −1 ) manifested two different QD families. Among the islands the smaller are coherent defect-free in nature, whereas the larger dots are plastically relaxed and hence optically inactive. Indium desorption from the island surface during the in situ annealing and N. Halder · R. Rashmi · S. Chakrabarti ( ) Centre

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“…The emission in sample B can be assigned to ground-state and excited-state transitions in the QDs. 35 The dependence of this emission on excitation power is shown in Fig. 7(b).…”

Section: Effect On the Optical Properties Of The Suppression Of MImentioning

confidence: 99%

Improved optical properties of InAs quantum dots for intermediate band solar cells by suppression of misfit strain relaxation

Xie

Prioli

Fischer

et al. 2016

Journal of Applied Physics

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The properties of InAs quantum dots (QDs) have been studied for application in intermediate band solar cells. It is found that suppression of plastic relaxation in the QDs has a significant effect on the optoelectronic properties. Partial capping plus annealing is shown to be effective in controlling the height of the QDs and in suppressing plastic relaxation. A force balancing model is used to explain the relationship between plastic relaxation and QD height. A strong luminescence has been observed from strained QDs, indicating the presence of localized states in the desired energy range. No luminescence has been observed from plastically relaxed QDs.

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Excited states in self-organized InAs/GaAs quantum dots: Theory and experiment

Cited by 224 publications

References 0 publications

Toward weak confinement regime in epitaxial nanostructures: Interdependence of spatial character of quantum confinement and wave function extension in large and elongated quantum dots

Toward weak confinement regime in epitaxial nanostructures: Interdependence of spatial character of quantum confinement and wave function extension in large and elongated quantum dots

A comprehensive study of the effect of in situ annealing at high growth temperature on the morphological and optical properties of self-assembled InAs/GaAs QDs

Improved optical properties of InAs quantum dots for intermediate band solar cells by suppression of misfit strain relaxation

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