Capillary-driven elastic attraction between quantum dots

Liu, Kailang; Berbézier, Isabelle; Favre, Luc; Ronda, A.; Abbarchi, Marco; Donnadieu, P.; Voorhees, Peter W.; Aqua, Jean-Noël

doi:10.1039/c9nr00238c

Cited by 12 publications

(11 citation statements)

References 69 publications

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“…These structures attract other diffusing atoms to form base layer seeds onto which the pyramids can grow. This mechanism and alignment of islands along two orthogonal directions defined by dimer rows orientation are confirmed by in situ and ex situ STEM observations in numerous experiments [3,6,19]. In Fig.…”

Section: Mechanisms In the First Added Layersupporting

confidence: 73%

“…Larger scale free energy models have also been used to explain the growth process such as the effect of the edge energy [15], the transition from two dimensional to three dimensional growth [16], the influence of the wetting layer [17] and the role of elastic interactions between islands [18,19]. Moreover, such models have been successfully used to describe Volmer-Weber growth of islands directly on the surface of the substrate in highly-mismatched systems [20,21], as well as the formation of 2D layers according to Frank-van der Merwe mechanisms in systems with close lattice parameters [22,23].…”

Section: Introductionmentioning

confidence: 99%

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Molecular dynamics simulations of the growth of Ge on Si

et al. 2020

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The initial stages of the growth of germanium on the dimer reconstructed Si(100) surface is modelled using molecular dynamics (MD). Pyramidal island structures are observed to form despite MD being carried out at a deposition rate faster than experiment. By an examination of transitions that can occur from intermediate structures that form in the MD simulations, growth mechanisms can be identified. The initial wetting occurs as a result of Ge atoms diffusing into the trenches between the dimer rows. This results in Ge-Ge or Ge-Si dimer chains growing in rows perpendicular to the original Si-Si dimer rows on the surface. It is shown how strained Ge pyramids with square bases can form by diffusing atoms joining together adjacent dimer rows. From these initial square-based structures, complex concerted motions are observed in which atoms in lower layers 'climb up' to higher layers. Similar structures grown in the pure Si case exhibit much higher energy barriers for the 'climbing up' process indicating that the effect of strain is to reduce the energy barriers for pyramid formation. In addition to the investigation of atomistic growth processes, surface energy effects are also examined, which show that a germanium-covered Si(100) surface containing shallow-angled pyramids is energetically more favourable than that grown as a flat monolayer.

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Section: Mechanisms In the First Added Layersupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of the growth of Ge on Si

et al. 2020

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“…The contact angle of 11 • (i.e. (105) facet) proved to be the optimum orientation, that is confirmed by numerous experimental results [10,14,27,48]. Surface energies of (105) and (100) facets for various numbers of added Ge layers were determined.…”

Section: Resultssupporting

confidence: 55%

“…In a theoretical analysis of the processes of nanostructure formation by the Stranski-Krastanow mechanism, it was usually assumed that the specific surface energies of the wetting layer and island faces are constant during growth [14,16,17,18,19,20,21]. However, a number of theoretical studies show that these values depend on the thickness of the two-dimensional layer [22,23,24,25,26,27]. Namely, with an increase in the thickness of the 2D layer, the specific surface energies tend to their equilibrium value, which is characteristic of an unstrained material.…”

Section: Introductionmentioning

confidence: 99%

Thickness-dependent surface energy and formation of epitaxial quantum dots

et al. 2020

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“…New experimental works constantly emerge, where novel unexpected results on epitaxy in Ge/Si system are being demonstrated. 9− 15 Bare silicon substrates with crystallographic orientations (100) and (111) were historically the first surfaces used for germanium epitaxy. 16−22 However, researchers have met the task to reduce the sizes of synthesized islands and to increase their surface density to a maximum extent.…”

Section: ■ Introductionmentioning

confidence: 99%

Evolution of Epitaxial Quantum Dots Formed by Volmer–Weber Growth Mechanism

Lozovoy

Коханенко

Dirko

et al. 2019

Crystal Growth & Design

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Germanium/silicon systems are among the most promising materials for development of current semiconductor electronics and photonics. Structures with germanium quantum dots on silicon are very interesting from the point of view of the creation of fast-speed transistors, photodetectors, and solar cells. The basic method of the synthesis of nanoislands is their self-organization in the process of molecular beam epitaxy. It was experimentally shown that ultrahigh surface densities (up to 1012–1013 cm–2) of nanometer-sized clusters may be achieved by deposition of germanium on oxidized rather than bare silicon surfaces. Nevertheless, this system with a thin layer of silicon oxide is poorly investigated. In this work, fundamental peculiarities of epitaxial formation and growth of quantum dots by the Volmer–Weber growth mechanism are considered. A kinetic model of nucleation and growth of three-dimensional islands by the Volmer–Weber mechanism based on the general nucleation theory is proposed for the first time. The developed model allows one to evaluate not only equilibrium values of a system with quantum dots (their average size and surface density), but also principally nonequilibrium parameters such as islands nucleation rate, size distribution function, and its time evolution. Dependencies of mean lateral size and surface density of Volmer–Weber quantum dots on the conditions of their synthesis (growth temperature and deposition rate) are obtained. The results of numerical simulations of Volmer–Weber growth for the Ge/SiO2/Si system show very good agreement with experimental data. The proposed theoretical model may be easily applied for other material systems where growth of islands by the Volmer–Weber mechanism is realized.

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Capillary-driven elastic attraction between quantum dots

Abstract: We present a novel self-assembly route to align SiGe quantum dots.

Cited by 12 publications

References 69 publications

Molecular dynamics simulations of the growth of Ge on Si

Molecular dynamics simulations of the growth of Ge on Si

Thickness-dependent surface energy and formation of epitaxial quantum dots

Evolution of Epitaxial Quantum Dots Formed by Volmer–Weber Growth Mechanism

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