Quantification of segregation and mass transport in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">In</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mi mathvariant="normal">A</mml:mi><mml:mi mathvariant="normal

Rosenauer, A.; Gerthsen, D.; Dyck, D. Van; Arzberger, M.; Böhm, G.; Abstreiter, G.

doi:10.1103/physrevb.64.245334

Cited by 103 publications

(64 citation statements)

References 33 publications

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“…Thus, the island formation requires considerable mass transfer by surface diffusion from the WL to the islands, as evidenced by several experiments. [12][13][14][15][16][17][18] The aim of the present study is to elucidate the underlying microscopic processes. As a first step in this direction, some of us have previously investigated the effect of strain on In diffusion on the GaAs͑001͒-c(4ϫ4) surface.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

et al. 2004

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In the Stranski-Krastanow growth of strained pseudomorphic films, material transport by surface diffusion plays a crucial role for the development of the three-dimensional island morphology. In an attempt to elucidate the atomistic aspects of this growth mode, we study diffusion of a single indium adatom on (1ϫ3)-and (2 ϫ3)-reconstructed subcritical In 2/3 Ga 1/3 As(001) films using first-principles total energy calculations of the corresponding adiabatic potential-energy surfaces ͑PES͒. We find that In diffusion is anisotropic, and substantially enhanced compared to the conventional GaAs͑001͒-c(4ϫ4) substrate. Special attention is also paid to the methodology of deriving the tracer diffusion coefficients of indium from knowledge of the PES, using the continuous-time random-walk formalism.

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Section: Introductionmentioning

confidence: 99%

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

et al. 2004

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“…can be divided in two groups-imaging and diffraction. The former originally exploits atomically resolved TEM micrographs with respect to lattice fringe distances~Bierwolf Bayle et al, 1994;Jouneau et al, 1994;Robertson et al, 1995;Rosenauer et al, 1998!. As the observed high-resolution pattern is formed by the interference of all diffracted beams passing the objective aperture, subsequent studies included partly extensive analysis of the phases of Bragg beams as a function of specimen thickness, orientation, composition, crystal potential Fourier components, lens aberrations, and defocus~Tillmann et al, 2000;Hÿtch & Plamann, 2001;Rosenauer et al, 2001;Rosenauer et al, 2006;Guerrero et al, 2007;Müller et al, 2010;Yu & Mader, 2010!. One disadvantage common to all high-resolution TEM techniques is the restricted field of view not only because the lattice fringe pattern must be sampled densely enough to measure fringe spacings precisely, but also because measured fringe distances need to be normalized tõ substrate! regions with known strain state, which may be too far away from the region of interest.…”

Section: Introductionmentioning

confidence: 99%

Strain Measurement in Semiconductor Heterostructures by Scanning Transmission Electron Microscopy

et al. 2012

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This article deals with the measurement of strain in semiconductor heterostructures from convergent beam electron diffraction patterns. In particular, three different algorithms in the field of~circular! pattern recognition are presented that are able to detect diffracted disc positions accurately, from which the strain in growth direction is calculated. Although the three approaches are very different as one is based on edge detection, one on rotational averages, and one on cross correlation with masks, it is found that identical strain profiles result for an In x Ga 1Ϫx N y As 1Ϫy /GaAs heterostructure consisting of five compressively and tensile strained layers. We achieve a precision of strain measurements of 7-9{10 Ϫ4 and a spatial resolution of 0.5-0.7 nm over the whole width of the layer stack which was 350 nm. Being already very applicable to strain measurements in contemporary nanostructures, we additionally suggest future hardware and software designs optimized for fast and direct acquisition of strain distributions, motivated by the present studies.

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“…The formation of InAs wetting layers (WLs) has attracted relatively little attention compared to quantum dot (QD) formation [26][27][28]. In the simple picture of Stranski-Krastanov growth, after the build-up of a critical amount of strain, 2D layer growth is followed by QD formation.…”

Section: Formation Of the Wetting Layermentioning

confidence: 99%

“…In atoms are redistributed from the InAs QD tops to the areas in between them during the QD levelling. They contribute to a several nanometres thick (In,Ga)As layer with an exponential In composition decay due to In segregation and Ga/In intermixing during overgrowth [28], reducing the lattice mismatch and, hence, the total energy of the system. Thus, the thickness and the In composition profile of the (In,Ga)As layer in between the InAs QDs strongly depends on the QD levelling and In segregation.…”

Section: Capping Temperature and Growth Interruptionsmentioning

confidence: 99%

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

Ulloa

Offermans

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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Quantification of segregation and mass transport inInxGa1−xA
A. Rosenauer
¹
,
D. Gerthsen
²
,
D. Van Dyck
³

et al.

Cited by 103 publications

References 33 publications

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

Strain Measurement in Semiconductor Heterostructures by Scanning Transmission Electron Microscopy

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

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Quantification of segregation and mass transport inInxGa1−xAA. Rosenauer1, D. Gerthsen2, D. Van Dyck3 et al.

Cited by 103 publications

References 33 publications

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

Anisotropic diffusion of In adatoms on pseudomorphicInxGa1−xAsfilms: First-p

Strain Measurement in Semiconductor Heterostructures by Scanning Transmission Electron Microscopy

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

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Product

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Quantification of segregation and mass transport inInxGa1−xA
A. Rosenauer
¹
,
D. Gerthsen
²
,
D. Van Dyck
³

et al.