Sunburst pattern by kinetic segregation in core-shell nanowires: A phase-field study

Bergamaschini, Roberto; Montalenti, Francesco; Miglio, Leo

doi:10.1016/j.apsusc.2020.146056

Cited by 6 publications

(16 citation statements)

References 39 publications

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“…This broadly explains why these are not observed in most previous low P containing GaAsP and low Al containing AlGaAs growths [6,7]. It may also be the reason for the inclined facet's lack of prominence and definition in the current sample compared to those in the thicker AlAs shells [26] and their simulations [27]. The preference shown in formation of secondary bands in nanowires with relatively larger diameters (within the range observed) (see Fig.…”

Section: Nano-facet Formation At the Alternating Verticessupporting

confidence: 52%

“…xs [27]. This aspect makes the real growth more complex and interdependent, together with the above discussed points, well explaining the difficulty seen in formation and continuation of the secondary P rich bands.…”

Section: Effect Of Growth Parameters and Compositionmentioning

confidence: 85%

“…A recent report demonstrated formation of similar nanofacets at the alternating vertices of AlAs nanowire shells which made them deviate from the regular hexagonal cross-section and form sharper vertices [26]. Another report [27] has successfully simulated this growth and shown that the formation of nanofacets is a combinational effect of surface energy anisotropy, orientation-dependent growth rates (which is enhanced in the <112> B directions for AlAs) and extremely low surface mobility of AlAs. However, the selection of polarity, is still unclear.…”

Section: Nano-facet Formation At the Alternating Verticesmentioning

confidence: 98%

“…GaAs growth is known to be less sensitive to polarity and form nanowires with regular hexagonal cross-section (or recover this shape after asymmetric growth) [7,26,27]. This is due to relatively long diffusion lengths of both, Ga and As [33].…”

Section: Nano-facet Formation At the Alternating Verticesmentioning

confidence: 99%

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Multiple radial phosphorus segregations in GaAsP core-shell nanowires

et al. 2020

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Highly faceted geometries such as nanowires are prone to form self-formed features, especially those that are driven by segregation. Understanding these features is important in preventing their formation, understanding their effects on nanowire properties, or engineering them for applications. Single elemental segregation lines that run along the radii of the hexagonal cross-section have been a common observation in alloy semiconductor nanowires. Here, in GaAsP nanowires, two additional P rich bands are formed on either side of the primary band, resulting in a total of three segregation bands in the vicinity of three of the alternating radii. These bands are less intense than the primary band and their formation can be attributed to the inclined nanofacets that form in the vicinity of the vertices. The formation of the secondary bands requires a higher composition of P in the shell, and to be grown under conditions that increase the diffusivity difference between As and P. Furthermore, it is observed that the primary band can split into two narrow and parallel bands. This can take place in all six radii, making the cross sections to have up to a maximum of 18 radial segregation bands. With controlled growth, these features could be exploited to assemble multiple different quantum structures in a new dimension (circumferential direction) within nanowires.

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Section: Nano-facet Formation At the Alternating Verticessupporting

confidence: 52%

Section: Effect Of Growth Parameters and Compositionmentioning

confidence: 85%

Section: Nano-facet Formation At the Alternating Verticesmentioning

confidence: 98%

Section: Nano-facet Formation At the Alternating Verticesmentioning

confidence: 99%

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Multiple radial phosphorus segregations in GaAsP core-shell nanowires

et al. 2020

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“…See, for example, the discussion in Backofen et al 25 . In fact, several simulations for realistic applications in materials science consider this model—see, for example, other studies 26‐38 —and claim that their large‐scale simulations would not be feasible without the additional degeneracy. The drawback of this DDCH model, which is termed RRV model in several publications, 22,31,36 is that it is nonvariational.…”

Section: Introductionmentioning

confidence: 99%

Doubly degenerate diffuse interface models of anisotropic surface diffusion

Salvalaglio

Selch

Voigt

et al. 2020

Math Methods in App Sciences

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We extend the doubly degenerate Cahn–Hilliard (DDCH) models for isotropic surface diffusion, which yield more accurate approximations than classical degenerate Cahn–Hilliard (DCH) models, to the anisotropic case. We consider both weak and strong anisotropies and demonstrate the capabilities of the approach for these cases numerically. The proposed model provides a variational and energy dissipative approach for anisotropic surface diffusion, enabling large‐scale simulations with material‐specific parameters.

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Towards 3D characterisation of site-controlled InGaAs pyramidal QDs at the nanoscale

et al. 2022

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In this work, we report an extensive investigation via transmission electron microscopy (TEM) techniques of InGaAs/GaAs pyramidal quantum dots (PQDs), a unique site-controlled family of quantum emitters that have proven to be excellent sources of single and entangled photons. The most striking features of this system, originating from their peculiar fabrication process, include their inherently 3-dimensional nature and their interconnection to a series of nanostructures that are formed alongside them, such as quantum wells and quantum wires. We present structural and chemical data from cross-sectional and plan view samples of both single and stacked PQDs structures. Our findings identify (i) the shape of the dot, being hexagonal and not triangular as previously assumed, (ii) the chemical distribution at the facets and QD area, displaying clear Indium diffusion, and (iii) a near absence of Aluminium (from the AlAs marker) at the bottom of the growth profile. Our results shed light on previously unreported structural and chemical features of PQDs, which is of extreme relevance for further development of this family of quantum emitters. Graphical abstract

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Sunburst pattern by kinetic segregation in core-shell nanowires: A phase-field study

Cited by 6 publications

References 39 publications

Multiple radial phosphorus segregations in GaAsP core-shell nanowires

Multiple radial phosphorus segregations in GaAsP core-shell nanowires

Doubly degenerate diffuse interface models of anisotropic surface diffusion

Towards 3D characterisation of site-controlled InGaAs pyramidal QDs at the nanoscale

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