Growth and structure of In0.5Ga0.5Sb quantum dots on GaP(001)

Sala, Elisa Maddalena; Stracke, Gernot; Selve, Sören; Niermann, Tore; Lehmann, Michael; Schlichting, S.; Nippert, Felix; Callsen, Gordon; Strittmatter, A.; Bimberg, D.

doi:10.1063/1.4962273

Cited by 14 publications

(22 citation statements)

References 30 publications

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“…Such process may lower the strain between QDs and GaP, where nominally the lattice mismatch was very high (nominally of ∼ 13 % between In 0.5 Ga 0.5 Sb/GaP) for enabling an usual Stranski-Krastanov QD growth. Therefore, such intermixing may have lowered the high mismatch, thus enabling the QD formation [14][15][16], similarly observed also in Abramkin et al [24] for GaSb/GaP QDs. Note, that we do not consider the described intermixing of Sb to the IL in order to make our results more general, and not depending on particular QD growth conditions.…”

Section: Choice Of Model Structurementioning

confidence: 76%

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Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

2019

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Detailed theoretical studies of the electronic structure of (InGa)(AsSb)/GaAs/GaP quantum dots are presented. This system is unique since it exhibits concurrently direct and indirect transitions both in real and momentum space and is attractive for applications in quantum information technology, showing advantages as compared to the widely studied (In,Ga)As/GaAs dots. We proceed from the inspection of the confinement potentials for k = 0 and k = 0 conduction and k = 0 valence bands, through the formulation of k · p calculations for k-indirect transitions, up to the excitonic structure of Γ-transitions. Throughout this process we compare the results obtained for dots on both GaP and GaAs substrates, enabling us to make a direct comparison to the (In,Ga)As/GaAs quantum dot system. We also discuss the realization of quantum gates.

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Section: Choice Of Model Structurementioning

confidence: 76%

“…the role of additional antimony incorporation, leading to In 1−x Ga x As y Sb 1−y /GaP QDs based on the experimental works of Sala et al [14][15][16]. Not only will we look at its suitability as optoelectronic material [17] but also -as discussed by Sala et al [15,16] -as material for QD-Flash memories.…”

Section: Introductionmentioning

confidence: 99%

Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

2019

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“…The growth of the In 1−x Ga x As y Sb 1−y QDs is based on the Stranski-Krastanov mode [59] and requires a few-ML-thick GaAs interlayer, which will be denoted here as IL. The growth of such material system has been previously studied by Sala et al in [46,57,60]. The growth procedure starts with a 250 nm GaP buffer layer, followed by a 20 nm Al 0.4 Ga 0.6 P layer providing a barrier for the photogenerated charge carriers, and 150 nm GaP at a temperature of 750 • C. The substrate temperature is then reduced to 500 • C and the following steps are carried out: (i) growth of a 5 ML-thick GaAs interlayer, required for QD formation [46,57], (ii) a short Sb-flush by supplying Triethylantimony for the QD samples S with and S cap , with a flux of 2.6 µmol/min, (iii) ∼ 0.51 ML In 1−x Ga x As y Sb 1−y QDs, (iv) a 1 ML thick GaSb cap for the sample S cap , (v) a growth interruptions (GRI) of 1 s without any precursor supply, and (vi) an additional GaP cap layer ∼ 6 nm thick (thickness optimized to maximize PL intensity of the structure, see Sect.…”

Section: Sample Fabrication and Structural Characterizationmentioning

confidence: 99%

Optical response of (InGa)(AsSb)/GaAs quantum dots embedded in a GaP matrix

et al. 2019

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The optical response of (InGa)(AsSb)/GaAs quantum dots (QDs) grown on GaP (001) substrates is studied by means of excitation and temperature-dependent photoluminescence (PL), and it is related to their complex electronic structure. Such QDs exhibit concurrently direct and indirect transitions, which allows the swapping of Γ and L quantum confined states in energy, depending on details of their stoichiometry. Based on realistic data on QD structure and composition, derived from high-resolution transmission electron microscopy (HRTEM) measurements, simulations by means of k · p theory are performed. The theoretical prediction of both momentum direct and indirect type-I optical transitions are confirmed by the experiments presented here. Additional investigations by a combination of Raman and photoreflectance spectroscopy show modifications of the hydrostatic strain in the QD layer, depending on the sequential addition of QDs and capping layer. A variation of the excitation density across four orders of magnitude reveals a 50 meV energy blueshift of the QD emission. Our findings suggest that the assignment of the type of transition, based solely by the observation of a blueshift with increased pumping, is insufficient. We propose therefore a more consistent approach based on the analysis of the character of the blueshift evolution with optical pumping, which employs a numerical model based on a semi-self-consistent configuration interaction method.

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“…All samples were fabricated via MOVPE in a horizontal Aixtron 200 reactor on GaP (001) substrates. After growing a 500 nm undoped GaP buffer at 750 °C, a 5 ML‐thick GaAs interlayer is deposited at 500 °C to enable the following QD formation, as already shown in our previous work . For a sample batch, an antimony‐flush with different durations ( t Sb ) has been used prior to QD deposition, with a triethyl‐antimony (TESb) input flux kept constant at 2.6 μmol min −1 .…”

Section: Sample Preparationmentioning

confidence: 99%

“…Type‐II QDs are therefore considered the best candidates as building blocks for the future QD‐Flash. Recently, we successfully demonstrated for the first time MOVPE growth of a new Sb‐based QD‐system, that is, InGaSb QDs embedded in a GaP matrix . Up to now, the longest published storage time for MOVPE‐grown QDs is 230 s at room temperature for In 0.5 Ga 0.5 As/GaP QDs .…”

Section: Introductionmentioning

confidence: 99%

MOVPE‐Growth of InGaSb/AlP/GaP(001) Quantum Dots for Nanoscale Memory Applications

Sala

Arikan

Bonato

et al. 2018

Physica Status Solidi (b)

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The structural and optical properties of InGaSb/GaP(001) type‐II quantum dots (QDs) grown by metalorganic vapor phase epitaxy (MOVPE) are studied. Growth strategies as growth interruption (GRI) after deposition of InGaSb and Sb‐flush prior to QD growth are used to tune the structural and optical properties of InGaSb QDs. The Sb‐flush affects the surface diffusion leading to more homogeneous QDs and to a reduction of defects. A ripening process during GRI occurs, where QD size is increased and QD‐luminescence remarkably improved. InGaSb QDs are embedded in GaP n + p‐diodes, employing an additional AlP barrier, and characterized electrically. A localization energy of 1.15 eV for holes in QDs is measured by using deep‐level transient spectroscopy (DLTS). The use of Sb in QD growth is found to decrease the associated QD capture cross‐section by one order of magnitude with respect to the one of In0.5Ga0.5As/GaP QDs. This leads to a hole storage time of almost 1 h at room temperature, which represents to date the record value for MOVPE‐grown QDs, making MOVPE of InGaSb/GaP related QDs a promising technology for QD‐based nano‐memories.

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Growth and structure of In0.5Ga0.5Sb quantum dots on GaP(001)

Cited by 14 publications

References 30 publications

Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

Optical response of (InGa)(AsSb)/GaAs quantum dots embedded in a GaP matrix

MOVPE‐Growth of InGaSb/AlP/GaP(001) Quantum Dots for Nanoscale Memory Applications

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