How kinetics drives the two- to three-dimensional transition in semiconductor strained heterostructures: The case of InAs∕GaAs(001)

Arciprete, F.; Placidi, E.; Sessi, Violetta; Fanfoni, M.; Patella, F.; Balzarotti, A.

doi:10.1063/1.2234845

Cited by 38 publications

(31 citation statements)

References 34 publications

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“…37 The dependence of the WL surface energy ͑and thus, of the island stability͒ on the coverage, inducing a tendency toward nucleation at overcritical WL thicknesses followed by WL consumption, seems to be indeed quite similar in the two systems. 19,28,29,38 …”

Section: Discussionmentioning

confidence: 99%

“…Particular care is dedicated to controlling the Ge deposition ͑reaching up to 0.025 MLs in resolution͒, unrolling and freezing the usual growth evolution along a space scale, i.e., obtaining an accurate deposition gradient across the wafer size ͑similarly to Ref. 19 where the onset of SK growth in InGaAs/GaAs͑001͒ is investigated͒, and in measuring on fly, still ex situ, the WL thickness by photoluminescence ͑PL͒. From the theoretical point of view, ab initio calculations of layer and surface energies are suitably matched to finite element method ͑FEM͒ simulations of the elastic energy in islands, allowing for the comparison of the thermodynamic stability of different shapes with respect to an increasing WL thickness.…”

Section: Introductionmentioning

confidence: 99%

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Key role of the wetting layer in revealing the hidden path of Ge/Si(001) Stranski-Krastanow growth onset

et al. 2009

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The commonly accepted Stranski-Krastanow model, according to which island formation occurs on top of a wetting layer ͑WL͒ of a certain thickness, predicts for the morphological evolution an increasing island aspect ratio with volume. We report on an apparent violation of this thermodynamic understanding of island growth with deposition. In order to investigate the actual onset of three-dimensional islanding and the critical WL thickness in the Ge/Si͑001͒ system, a key issue is controlling the Ge deposition with extremely high resolution ͓0.025 monolayer ͑ML͔͒. Atomic force microscopy and photoluminescence measurements on samples covering the deposition range 1.75-6.1 ML, taken along a Ge deposition gradient on 4 in. Si substrates and at different growth temperatures ͑T g ͒, surprisingly reveal that for T g Ͼ 675°C steeper multifaceted domes apparently nucleate prior to shallow ͕105͖-faceted pyramids, in a narrow commonly overlooked deposition range. The puzzling experimental findings are explained by a quantitative modeling of the total energy with deposition. We accurately matched ab initio calculations of layer and surface energies to finite-element method simulations of the elastic energy in islands, in order to compare the thermodynamic stability of different island shapes with respect to an increasing WL thickness. Close agreement between modeling and experiments is found, pointing out that the sizeable progressive lowering of the surface energy in the first few MLs of the WL reverts the common understanding of the SK growth onset. Strong similarities between islanding in SiGe and III/V systems are highlighted.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Key role of the wetting layer in revealing the hidden path of Ge/Si(001) Stranski-Krastanow growth onset

et al. 2009

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“…In the literature, the above experimental observations [89,[123][124][125][126][127][128] have often been taken as strong experimental evidence to support the view that InAs QD formation should be a surface process remarkably similar to adatom aggregation in homoepitaxial growth in the submonolayer regime. However, it will be further demonstrated in Section 4 that the outcome of practical epitaxial growth of InAs QDs depends sensitively on the growth parameters, such as the flux rate F and temperature T ; although some experimental data in the literature obtained under certain growth conditions seem to be consistent with Eqs.…”

Section: Fitting Experimental Data On the Density And Size Distributimentioning

confidence: 80%

“…In contrast, from the experimental viewpoint, InAs QD formation is definitely a self-limited growth process, and the growth power law s av ∝ θ z for an aggregation process makes no sense for InAs QD growth behavior. Therefore, the apparent fitting of the experimental data reported in these references [89,[123][124][125][126][127][128] may only demonstrate that both the universal laws, Eqs. (3.2.2.9) and (3.2.3.6), are very versatile and flexible in fitting experimental data obtained in a large number of cases, and may provide little insight into the nature of the InAs QD formation process.…”

Section: Fitting Experimental Data On the Density And Size Distributimentioning

confidence: 99%

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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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