Self-assembled lateral Bi-quantum-dot molecule formation by gas-source molecular beam epitaxy

Suraprapapich, S.; Shen, Yue; Odnoblyudov, V. A.; Fainman, Yeshaiahu; Panyakeow, Somsak; Tu, C. W.

doi:10.1016/j.jcrysgro.2006.11.120

Cited by 20 publications

(22 citation statements)

References 16 publications

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“…Details on the growth process can be found in Refs. [18] and [19]. Due to residual p-type doping during the MBE growth, photoluminescence (PL) signals from the ground state of the ensemble QDs are dominated by recombination from positively charged excitons (called positive trions) over the studied temperature range of 150-300 K. We used a tuneable Ti:sapphire laser as an excitation source.…”

Section: Samplesmentioning

confidence: 99%

The Hanle effect and electron spin polarization in InAs/GaAs quantum dots up to room temperature

et al. 2012

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Abstract. The Hanle effect in InAs/GaAs quantum dots (QDs) is studied under optical orientation as a function of temperature over the range of 150-300 K, with the aim to understand the physical mechanism responsible for the observed sharp increase of electron spin polarization with increasing temperature. The deduced spin lifetime T s of positive trions in the QDs is found to be independent of temperature, and is also insensitive to excitation energy and density. It is argued that the measured T s is mainly determined by the longitudinal spin flip time (T 1 ) and the spin dephasing time (T 2 * ) of the studied QD ensemble, of which both are temperature-independent over the studied temperature range and the latter makes a larger contribution. The observed sharply rising QD spin polarization degree with increasing temperature, on the other hand, is shown to be induced by an increase in spin injection efficiency from the barrier/wetting layer and also by a moderate increase in spin detection efficiency of the QD.PACS numbers: 73.21.La, 78.67.Hc, 72.25.Fe IntroductionSpins in semiconductor quantum dots (QDs) are the subject of extensive current research due to their weak interaction with the solid state environment, resulting in long spin lifetimes and the proposal for their application in spintronics and quantum information technology [1][2][3]. To this end, studies of spin injection and detection are important tasks to advance both our understanding of the relevant physical processes and to guide the design of improved structures for spintronic applications. Spin-related properties of QDs have in past years been investigated extensively, mainly at low temperatures, largely thanks to the availability of modern single-dot optical spectroscopy such as micro-photoluminescence (-PL) and scanning near-field optical microscopy (SNOM) [4][5][6][7][8][9][10]. Unfortunately, applications of these techniques for studies of QDs have been extremely restricted at elevated temperatures due to drastically decreasing emission intensity with increasing temperature. As a result, detailed studies and understanding of spin properties of QDs at temperatures close to room temperature (RT), highly relevant for practical applications, remain very limited.Recently, we reported a dramatic increase in electron spin polarization degree of InAs/GaAs QDs at high temperatures [11]. Polarization values up to 35% in the QD ground state at RT have been found, indicating at least equally high spin detection efficiency. In this work we carry out detailed studies of the Hanle effect [12], i.e. the depolarization effect in a transverse magnetic field, in InAs/GaAs QDs. Our aim is to determine the temperature dependence of the QD electron spin lifetime

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Section: Samplesmentioning

confidence: 99%

The Hanle effect and electron spin polarization in InAs/GaAs quantum dots up to room temperature

et al. 2012

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“…[88] This partial capping technique was also used to create different structures, like InAs quantum rings. The QDMs grown by this method have an average center-to-center distance of 22 nm and a height of 2-4 nm.…”

Section: Qdms Based On Partial Capping Techniquementioning

confidence: 99%

Self‐Assembled Quantum Dot Molecules

et al. 2009

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Semiconductor quantum dot molecules (QDMs) are systems composed of two or more closely spaced and interacting QDs. QDMs are receiving much attention both as playground for studying coupling and energy transfer processes between “artificial atoms” and as new systems, which substantially extend the range of possible applications of QDs. QDMs can be conveniently fabricated by self‐assembly either through chemical synthesis or epitaxial growth. Although QDMs relying on the random occurrence of nearby QDs can be used for fundamental studies, special fabrication protocols must be used to create QDMs with well‐defined properties. In this article, we focus on self‐assembled QDMs obtained by epitaxial growth and embedded in a semiconductor matrix, which are appealing for the possible realization of quantum gates based on two‐level systems defined in QDs. We provide a comprehensive overview of the development and current stage of the research on QDMs composed of vertically (in the growth direction) or laterally (in the growth plane) aligned QDs. The review highlights some recent milestone works and points out the challenges and future directions in the field.

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“…Each as-grown QD in the first SA-QD layer is transformed into a quantum ring after partial-capping with 6 ML of GaAs. When additional 0.6 ML of InAs is deposited, DQDs are formed, with the two QDs oriented along the [11 0] crystallographic direction [14]. The total QD density is 1.1 Â10 10 cm À2 , consisting of 80% DQDs and 20% single dots.…”

Section: Article In Pressmentioning

confidence: 99%

“…The total QD density is 1.1 Â10 10 cm À2 , consisting of 80% DQDs and 20% single dots. The average dot height is $4 nm and center-to-center spacing is $22 nm [14].…”

Section: Article In Pressmentioning

confidence: 99%

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The effects of rapid thermal annealing on doubled quantum dots grown by molecular beam epitaxy

Suraprapapich

Shen

Fainman

et al. 2009

Journal of Crystal Growth

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Self-assembled lateral Bi-quantum-dot molecule formation by gas-source molecular beam epitaxy

Cited by 20 publications

References 16 publications

The Hanle effect and electron spin polarization in InAs/GaAs quantum dots up to room temperature

The Hanle effect and electron spin polarization in InAs/GaAs quantum dots up to room temperature

Self‐Assembled Quantum Dot Molecules

The effects of rapid thermal annealing on doubled quantum dots grown by molecular beam epitaxy

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