Single site-controlled In(Ga)As/GaAs quantum dots: growth, properties and device integration

Schneider, Christian; Huggenberger, A.; Sünner, T.; Heindel, Tobias; Strauß, M.; Göpfert, S.; Weinmann, P.; Reitzenstein, S.; Worschech, L.; Kamp, M.; Höfling, Sven; Forchel, A.

doi:10.1088/0957-4484/20/43/434012

Cited by 84 publications

(79 citation statements)

References 53 publications

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“…A detailed description of the fabrication techniques is given in Ref. 34. Short circuiting the drain contact with lateral gates provides the memristive operation.…”

Section: (A)mentioning

confidence: 99%

Mimicking of pulse shape-dependent learning rules with a quantum dot memristor

Maier

Hartmann

Dias

et al. 2016

Journal of Applied Physics

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We present the realization of four different learning rules with a quantum dot memristor by tuning the shape, the magnitude, the polarity and the timing of voltage pulses. The memristor displays a large maximum to minimum conductance ratio of about 57000 at zero bias voltage. The high and low conductances correspond to different amounts of electrons localized in quantum dots, which can be successively raised or lowered by the timing and shapes of incoming voltage pulses. Modifications of the pulse shapes allow altering the conductance change in dependence on the time difference. Hence, we are able to mimic different learning processes in neural networks with a single device. In addition, the device performance under pulsed excitation is emulated combining the Landauer-Büttiker formalism with a dynamic model for the quantum dot charging, which allows explaining the whole spectrum of learning responses in terms of structural parameters that can be adjusted during fabrication such as gating efficiencies and tunneling rates. The presented memristor may pave the way for future artificial synapses with a stimulus-dependent capability of learning.

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“…A detailed description of the fabrication techniques is given in Ref. 34. Short circuiting the drain contact with lateral gates provides the memristive operation.…”

Section: (A)mentioning

confidence: 99%

Mimicking of pulse shape-dependent learning rules with a quantum dot memristor

Maier

Hartmann

Dias

et al. 2016

Journal of Applied Physics

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“…The PCA technique was applied to all layers except the topmost in order to accomplish a spectral detuning between the different layers to facilitate single SCQD studies. The samples were investigated by optical spectroscopy in order to assess the effect of a stacked growth of QDs on their emission linewidths 20 . In addition, it was studied whether dry or wet chemical leads to better optical quality of the SCQDs.…”

Section: Growth Of Site Controlled Qds On Prepatterned Substratesmentioning

confidence: 99%

“…5 to the calculated LDOS we have extracted the decay rates Γ 0.90 0.20 and Γ 0.99 0. 20 . Taking Eqs.…”

Section: Quantum Efficiency and Oscillator Strength Of Site Controllementioning

confidence: 99%

Cavity quantum electrodynamics studies with site-controlled InGaAs quantum dots integrated into high quality microcavities

Reitzenstein

Schneider

Albert

et al. 2011

Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling VIII

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Semiconductor quantum dots (QDs) are fascinating nanoscopic structures for photonics and future quantum information technology. However, the random position of self-organized QDs inhibits a deterministic coupling in devices relying on cavity quantum electrodynamics (cQED) effects which complicates, e.g., the large scale fabrication of quantum light sources. As a result, large efforts focus on the growth and the device integration of site-controlled QDs. We present the growth of low density arrays of site-controlled In(Ga)As QDs where shallow etched nanoholes act as nucleation sites. The nanoholes are located relative to cross markers which allows for a precise spatial alignment of the site-controlled QDs (SCQDs) and the photonic modes of high quality microcavites with an accuracy better than 50 nm. We also address the optical quality of the SCQDs in terms of the single SCQD emission mode linewidth, the oscillator strength and the quantum efficiency. A stacked growth of strain coupled SCQDs forming on wet chemically etched nanoholes provide the smallest linewidth with an average value of 210 µeV. Using time resolved photoluminescence studies on samples with a varying thickness of the capping layer we determine a quantum efficiency of the SCQD close to 50 % and an oscillator strength of about 10. Finally, single photon emission with associated with g (2) (0) = 0.12 of a weakly coupled SCQD -micropillar system will be presented.

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“…At first nucleation centres are defined on a planar GaAs surface by means of e-beam lithography and etching. After thoroughly removing resists and oxides [38] regrowth on the patterned surface is performed, initialized by a thin GaAs buffer layer to smooth the surface and subsequent deposition of InAs QDs in single layers or stacked QD layers at low growth rates. This technique allowed us to direct the nucleation of the InAs QDs to a high degree as shown in scanning electron microscopy images on uncapped QDs in Fig.…”

Section: Quantum Dot Growthmentioning

confidence: 99%

Semiconductor Cavity Quantum Electrodynamics with Single Quantum Dots

et al. 2009

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This paper summarizes recent progress achieved in the field of semiconductor cavity quantum electrodynamics with single quantum dots with the focus being on micropillar cavities. Light-matter interaction both in the strong and weak coupling regime is presented. Resonance tuning of the quantum dot by temperature, electric fields and magnetic fields is demonstrated while the strong coupling regime can be reached. Additionally, deterministic device integration of single positioned quantum dots is reported by a combination of site controlled quantum dot growth via directed nucleation and subsequent device alignment to overcome the degree of randomness of the quantum dot position in so far most common quantum dot-cavity systems.

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Single site-controlled In(Ga)As/GaAs quantum dots: growth, properties and device integration

Cited by 84 publications

References 53 publications

Mimicking of pulse shape-dependent learning rules with a quantum dot memristor

Mimicking of pulse shape-dependent learning rules with a quantum dot memristor

Cavity quantum electrodynamics studies with site-controlled InGaAs quantum dots integrated into high quality microcavities

Semiconductor Cavity Quantum Electrodynamics with Single Quantum Dots

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