Time-resolved studies of annealed InAs/GaAs self-assembled quantum dots

Malik, Surama; Ru, Eric C. Le; Childs, David; Murray, R.

doi:10.1103/physrevb.63.155313

Cited by 72 publications

(50 citation statements)

References 33 publications

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“…11 The arsenic decapping anneal was approximately 400°C for 15 min, a temperature well below that used to modify the optical properties of InAs-GaAs QDs. 12 Residual submonolayer contamination by oxygen and carbon was normally detected by Auger electron spectroscopy, but neither this nor the anneal itself materially affect the In profile results presented here. Ion scattering experiments were performed using the UK MEIS Facility at Daresbury Laboratories.…”

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confidence: 98%

Composition profiles of InAs–GaAs quantum dots determined by medium-energy ion scattering

Quinn

Wilson

Hatfield

et al. 2005

Applied Physics Letters

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confidence: 98%

Composition profiles of InAs–GaAs quantum dots determined by medium-energy ion scattering

Quinn

Wilson

Hatfield

et al. 2005

Applied Physics Letters

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“…Despite a number of reports of the effects of annealing on the properties of In(Ga)AsGaAs QDs, these as-grown dots generally emit significantly below 1.3µm at room temperature and there have been relatively few studies of the effects of annealing on QDs designed to emit at 1.3µm with the required high density for laser applications [11,12,13]. In addition, very few optical studies of the effects of annealing have related the observed changes directly to changes in the structural properties [9].…”

Section: Introductionmentioning

confidence: 99%

Magneto-optical study of thermally annealed InAs-InGaAs-GaAs self-assembled quantum dots

Nabavi¹,

Badcock²,

Nuytten³

et al. 2009

Journal of Applied Physics

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We report a magneto-optical study of InAs-InGaAs-GaAs self-assembled quantum dots (QDs) subjected to post-growth thermal annealing at different temperatures. At low temperatures annealing strongly affects the bimodal distribution of QDs, at higher temperatures a strong blue shift of the emission occurs. Magneto-photoluminescence reveals that the annealing increases the QD size, with a larger effect occurring along the growth axis, and decreases the carrier effective masses. The main contribution to the blue shift is deduced to be an increase in the average Ga composition of the QDs. The inadvertent annealing which occurs during the growth of the upper AlGaAs cladding layer in laser structures is also studied.

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“…The 7.5% value is the measured steadystate spin polarization in the QDs, P spin , due to spin injection effects. The ratio T S / describes the exciton spin scattering in the dots and is estimated to be equal to 0.375± 0.05, using the previously obtained value of 510 ps for g * T S , a ground state exciton lifetime of 800 ps, from time-resolved studies in our InAs dots 19 and a g * -factor estimate of −1.7. A ⌸ value of 20± 3.25% is then obtained; we note that a correct estimate of ⌸ depends on a correct estimate of the g * factor.…”

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confidence: 99%

Oblique Hanle Measurements of InAs/GaAs Quantum Dot Spin-Light Emitting Diodes

Itskos¹,

Harbord²,

Clowes³

et al. 2007

AIP Conference Proceedings

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We report on studies of electrical spin injection from ferromagnetic Fe contacts into semiconductor light emitting diodes containing single layers of InAs/ GaAs self-assembled quantum dots ͑QDs͒. An oblique magnetic field is used to manipulate the spin of the injected electrons in the semiconductor. This approach allows us to measure the injected steady-state spin polarization in the QDs, P spin as well as estimate the spin losses in the QD spin detector. After subtraction of magneto-optical effects not related to spin injection, we measured a P spin of 7.5% at 15 K and estimated an injected spin polarization before QD recombination of around 20%. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2163074͔ Electrical injection of spin polarized carriers from a magnetic contact into a semiconductor is essential for the implementation of spintronic devices.1,2 An accurate way to quantify the spin injection process is to utilize a spin-light emitting diode ͑spin-LED͒. Such a device uses a magnetic contact to electrically inject spin polarized carriers into a LED structure and employs the radiative selection rules to relate the degree of the circular polarization of the emitted light to the injected carrier spin polarization. Ferromagnetic metals are attractive as magnetic contacts in spin-LEDs due to their high Curie temperatures and their well-studied structural and magnetic properties. Recently, high spin injection efficiencies have been achieved in devices where a conventional ferromagnetic metal such as Fe, Co, Ni and their alloys were used to electrically inject spin-polarized electrons via a Schottky 3-5 or an oxide tunnel barrier 6-9 into a semiconductor LED structure.In the great majority of these devices, bulk semiconductors or quantum wells have been used as the recombination region. Spin relaxation in these is mainly caused by momentum-dependent spin interactions that are in general fast because of the availability of a continuum of energy states. These mechanisms should be inefficient in spin-LEDs based on quantum dots ͑QDs͒ due to their three-dimensional carrier confinement, which results in a discrete density of states. Yet, there have been few reports on electrical spin injection in QD-based spin-LEDs, 10-12 only one of which 12 used a ferromagnetic contact as injector. In the latter, a large magnetic field ͑B Ͼ 2 T͒ was used to bring the Fe film magnetization out of plane ͑hard axis͒ and inject electrons with spins along the surface normal ͑Faraday geometry͒. An injected spin polarization in the QDs, P spin of 5% was measured; importantly the polarization was insensitive to the temperature and persisted to 300 K, confirming the potential of quantum dots as spin detectors in spin-LEDs. We demonstrate here electrical spin injection from ferromagnetic Fe contacts into semiconductor LED structures containing single layers of InAs/ GaAs self-assembled quantum dots ͑QDs͒. The spins are injected along the sample layers ͑Fe easy axis͒ under application of a small oblique magnetic field ͑B Ͻ 100 mT͒. The ...

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Time-resolved studies of annealed InAs/GaAs self-assembled quantum dots

Cited by 72 publications

References 33 publications

Composition profiles of InAs–GaAs quantum dots determined by medium-energy ion scattering

Composition profiles of InAs–GaAs quantum dots determined by medium-energy ion scattering

Magneto-optical study of thermally annealed InAs-InGaAs-GaAs self-assembled quantum dots

Oblique Hanle Measurements of InAs/GaAs Quantum Dot Spin-Light Emitting Diodes

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