RHEED metrology of Stranski–Krastanov quantum dots

Feltrin, A.; Freundlich, A.

doi:10.1016/j.jcrysgro.2006.11.294

Cited by 25 publications

(20 citation statements)

References 9 publications

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“…At the moment, only a few techniques, e.g. reflection high energy electron diffraction (RHEED) 19 , in-situ accumulated stress measurements 20 , and spectroscopic ellipsometry 21 , can give real time information during the growth and thereby help monitoring the growth. But if such techniques provide valuable information about the growth surface, the averaging nature of the techniques make them of little use when study atomic-scale processes such as intermixing or segregation.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Monte Carlo simulations and cross-sectional scanning tunneling microscopy as tools to investigate the heteroepitaxial capping of self-assembled quantum dots

et al. 2012

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The growth of self-assembled quantum dots has been intensively studied in the last decade. Despite substantial efforts, a number of details of the growth process remain unknown. The reason is the inability of current characterization techniques to image the growth process in real time. In the current work this limitation is alleviated by the use of kinetic Monte-Carlo simulations in conjunction with cross-sectional scanning tunneling microscopy. The two techniques are used to study the method of strain engineering as a procedure to control the height of quantum dots. We show for the first time that fully three-dimensional kinetic Monte-Carlo simulations can be matched with the experimentally obtained morphology of buried quantum dots and that combination of the two techniques provides details of the growth process that hitherto could not be obtained.

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Section: Introductionmentioning

confidence: 99%

Kinetic Monte Carlo simulations and cross-sectional scanning tunneling microscopy as tools to investigate the heteroepitaxial capping of self-assembled quantum dots

et al. 2012

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“…In MBE InAs/GaAs(001), the dynamic evolution of an ensemble of QDs was generally monitored in situ via either RHEED [247][248][249][250][251], the photoluminescence optical properties [252], or XRD [253]. From these experimental observations, a timescale of at least a few seconds for InAs QD growth was extracted; this was regarded as quite fast in comparison with the deposition rate (which is usually 0.1 ML/s).…”

Section: Experimental Observations Of the Timescale Of Inas Qd Growthmentioning

confidence: 99%

“…In Section 3.6, it was mentioned that the timescale for QD growth completion was estimated by techniques such as RHEED [247][248][249][250][251], photoluminescence [252], and XRD [253]. A more direct and accurate measurement method for extracting the timescale is based on snapshots obtained in neighboring regions on the growth surface using STM and ATM.…”

Section: -28mentioning

confidence: 99%

Self-assembly of InAs quantum dots on GaAs(001) by molecular beam epitaxy

Jin

2015

Front. Phys.

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Currently, the nature of self-assembly of three-dimensional epitaxial islands or quantum dots (QDs) in a lattice-mismatched heteroepitaxial growth system, such as InAs/GaAs(001) and Ge/Si(001) as fabricated by molecular beam epitaxy (MBE), is still puzzling. The purpose of this article is to discuss how the self-assembly of InAs QDs in MBE InAs/GaAs(001) should be properly understood in atomic scale. First, the conventional kinetic theories that have traditionally been used to interpret QD self-assembly in heteroepitaxial growth with a significant lattice mismatch are reviewed briefly by examining the literature of the past two decades. Second, based on their own experimental data, the authors point out that InAs QD self-assembly can proceed in distinctly different kinetic ways depending on the growth conditions and so cannot be framed within a universal kinetic theory, and, furthermore, that the process may be transient, or the time required for a QD to grow to maturity may be significantly short, which is obviously inconsistent with conventional kinetic theories. Third, the authors point out that, in all of these conventional theories, two well-established experimental observations have been overlooked: i) A large number of “floating” indium atoms are present on the growing surface in MBE InAs/GaAs(001); ii) an elastically strained InAs film on the GaAs(001) substrate should be mechanically unstable. These two well-established experimental facts may be highly relevant and should be taken into account in interpreting InAs QD formation. Finally, the authors speculate that the formation of an InAs QD is more likely to be a collective event involving a large number of both indium and arsenic atoms simultaneously or, alternatively, a morphological/structural transformation in which a single atomic InAs sheet is transformed into a three-dimensional InAs island, accompanied by the rehybridization from the sp 2-bonded to sp 3-bonded atomic configuration of both indium and arsenic elements in the heteroepitaxial growth system.

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“…Moreover, InAs͑137͒A is relevant since this surface orientation has been found to occur as side facet on InAs quantum dots grown on various GaAs substrates. [10][11][12] In a recent theoretical study, we suggested that the shape evolution of these The InAs͑137͒ surface plane is inclined relative to both the ͑100͒ and the ͑110͒ directions. One surface unit cell contains an As dimer, two threefold coordinated cations ͑one of which is visible in the figure͒, and one threefold coordinated As atom.…”

Section: Introductionmentioning

confidence: 98%

Atomic processes in molecular beam epitaxy on strained InAs(137): A density-functional theory study

Kratzer

Hammerschmidt

2009

Phys. Rev. B

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The atomic processes in molecular beam epitaxy of InAs on the InAs͑137͒ surface are investigated by means of first-principles total-energy calculations. We consider layer-by-layer growth on InAs͑137͒ facets as a typical process during the evolution of shallow InAs islands in the Stranski-Krastanov growth mode of InAs on GaAs that is exploited for the self-assembly of heteroepitaxial quantum dots. From the calculated energetics we conclude that a growth scenario where an As 2 molecule adsorbs on a single In adatom, followed by capture of another In adatom, is most likely. Moreover, our calculations of the potential-energy surface for In adatoms on the InAs͑137͒ surface show that In adatoms are highly mobile. Surface diffusion on InAs͑137͒ is found to be almost isotropic with energy barriers Ͻ0.3 eV for adatom hopping. Aiming at an understanding of the growth processes at the strained side facets of quantum dots, we extend our calculations to isotropically strained InAs͑137͒ facets. It is found that the compressive strain present on side facets of shallow InAs islands on GaAs leads to a considerable lowering of the binding energy of In adatoms. The height of diffusion barriers is found to be less affected by the strain. Most importantly, the intermediate species consisting of an In adatom plus an adsorbed As 2 molecule is destabilized by compressive strain in excess of −5%. This finding leads us to the conclusion that layer growth on InAs͑137͒ facets ceases in highly strained regions of InAs islands on GaAs, in line with the observed shape evolution of such islands.

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RHEED metrology of Stranski–Krastanov quantum dots

Cited by 25 publications

References 9 publications

Kinetic Monte Carlo simulations and cross-sectional scanning tunneling microscopy as tools to investigate the heteroepitaxial capping of self-assembled quantum dots

Kinetic Monte Carlo simulations and cross-sectional scanning tunneling microscopy as tools to investigate the heteroepitaxial capping of self-assembled quantum dots

Self-assembly of InAs quantum dots on GaAs(001) by molecular beam epitaxy

Atomic processes in molecular beam epitaxy on strained InAs(137): A density-functional theory study

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