Nonuniform Composition Profile in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>In</mml:mi></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mi>As</mml:mi></mml:math>Alloy Quantum Dots

Liu, N.; Tersoff, J.; Baklenov, O.; Holmes, A. L.; Shih, Chih‐Kang

doi:10.1103/physrevlett.84.334

Cited by 266 publications

(170 citation statements)

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“…any direct way of determining a possible lateral variation in composition, as found recently by Liu et al [5], who deposited In 0.5 Ga 0.5 As. Atomistic calculations of strain relaxation based on semiclassical potentials show, however, that the determined strain distribution in our sample is self-consistent with a laterally homogeneous composition, but not with an "inverted-cone In-profile" as found in Ref.…”

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confidence: 67%

“…Atomistic calculations of strain relaxation based on semiclassical potentials show, however, that the determined strain distribution in our sample is self-consistent with a laterally homogeneous composition, but not with an "inverted-cone In-profile" as found in Ref. [5] for buried islands. Likewise, also finite element calculations show that the measured strain distribution [ Fig.…”

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confidence: 80%

“…While deemed to be promising candidates for future applications as quantum dots, in which electrons are confined in all three directions of space, only a few quantitative experimental data are available concerning the distribution of chemical composition and strain fields in such islands. Cross-sectional scanning tunneling microscopy has been applied successfully to determine the interdiffusion profiles of buried islands [5]. It has, however, been found that the chemical composition of uncapped islands can be different from that of the deposited material.…”

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confidence: 99%

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Nanometer-Scale Resolution of Strain and Interdiffusion in Self-AssembledInAs/GaAsQuantum Dots

et al. 2000

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Tomographic nanometer-scale images of self-assembled InAs͞GaAs quantum dots have been obtained from surface-sensitive x-ray diffraction. Based on the three-dimensional intensity mapping of selected regions in reciprocal space, the method yields the shape of the dots along with the lattice parameter distribution and the vertical interdiffusion profile on a subnanometer scale. The material composition is found to vary continuously from GaAs at the base of the dot to InAs at the top.

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confidence: 80%

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Nanometer-Scale Resolution of Strain and Interdiffusion in Self-AssembledInAs/GaAsQuantum Dots

et al. 2000

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“…However, it is impossible to quantitatively determine all these parameters in experiments [25][26][27]. We circumvent this difficult by defining several physical parameters to fully characterize the statistical features of FSS and polarization angle in QDEs.…”

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Statistical properties of exciton fine structure splitting and polarization angles in quantum dot ensembles

et al. 2014

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We propose an effective model to describe the statistical properties of exciton fine structure splitting (FSS) and polarization angle of quantum dot ensembles (QDEs). We derive the distributions of FSS and polarization angle for QDEs and show that their statistical features can be fully characterized using at most three independent measurable parameters. The effective model is confirmed using atomistic pseudopotential calculations as well as experimental measurements for several rather different QDEs. The model naturally addresses three fundamental questions that are frequently encountered in theories and experiments: (I) Why the probability of finding QDs with vanishing FSS is generally very small? (II) Why FSS and polarization angle differ dramatically from QD to QD? and (III) Is there any direct connection between FSS, optical polarization and the morphology of QDs? The answers to these fundamental questions yield a completely new physical picture for understanding optical properties of QDEs.

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“…From X-STM and photocurrent experiments, it has been shown that low-growth rate InAs/GaAs QDs have an increasing indium concentration in the growth direction [47,48]. However, other groups have reported InGaAs QDs with laterally non-uniform indium compositions showing an inverted-triangle, trumpet or truncated reversed-cone shape [26,[49][50][51]. We find that the indium distribution of our low-growth rate …”

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confidence: 47%

InAs Quantum Dot Formation Studied at the Atomic Scale by Cross-sectional Scanning Tunnelling Microscopy

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Koenraad

2008

Handbook of Self Assembled Semiconductor Nanostructures for Novel Devices in Photonics and Electronics

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Introduction Quantum dot formationSelf-assembled quantum dots (QDs) have attracted much attention in the last years [1,2]. These nanostructures are very interesting from a scientific point of view because they form nearly ideal zero-dimensional systems in which quantum confinement effects become very important. These unique properties also make them very interesting from a technological point of view. For example, InAs QDs are employed in QD lasers [3,4], single electron transistors [5], midinfrared detectors [6,7], single-photon sources [8,9], etc. InAs QDs are commonly created by the Stranski-Krastanov growth mode when InAs is deposited on a substrate with a bigger lattice constant, like GaAs or InP [10]. Above a certain critical thickness of InAs, three-dimensional islands are spontaneously formed on top of a wetting layer (WL) to reduce the strain energy. Once created, the QDs are subsequently capped, a step which is required for any device application.For any application based on InAs QDs, an accurate control of their electronic properties is required. The electron and hole states in the dot are very sensitive to the QD size, shape and composition (as well as to the surrounding material), and therefore an accurate control of the QD structural properties is necessary for applications. This explains the strong effort dedicated in the last years to the structural characterization of QDs [11], which is essential in order to have a deep understanding of the QD formation process. Although a lot of effort has been dedicated to study surface QDs, there are relatively few studies focused on the effect of the capping process [12][13][14][15][16][17][18][19][20]. Some of these studies have already shown significant differences in size, shape and composition between uncapped and capped QDs. For example, an important collapse of the QD height has been reported for InAs/GaAs QDs capped with GaAs [14,15,[17][18][19], revealing the big influence of the capping process on the structural properties of the QDs. Indeed, critical issues affecting the dot take place during capping like dot decomposition, intermixing, segregation, As/P exchange and composition modulation in the capping layer. This means that the real buried QDs must be studied in order to understand the complete QD formation process. Cross-sectional scanning tunnelling microscopy is an especially useful technique for this purpose, because it allows the structure of the capped dots at the atomic scale to be assessed. Cross-sectional scanning tunnelling microscopy (X-STM)The scanning tunnelling microscope is part of the family of scanning probe microscopes, which are able to provide direct real space information of a physical property at the atomic scale. This

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Nonuniform Composition Profile inIn0.5Ga0.5AsAlloy Quantum Dots

Cited by 266 publications

References 22 publications

Nanometer-Scale Resolution of Strain and Interdiffusion in Self-AssembledInAs/GaAsQuantum Dots

Nanometer-Scale Resolution of Strain and Interdiffusion in Self-AssembledInAs/GaAsQuantum Dots

Statistical properties of exciton fine structure splitting and polarization angles in quantum dot ensembles

InAs Quantum Dot Formation Studied at the Atomic Scale by Cross-sectional Scanning Tunnelling Microscopy

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