A comparison of strain relief behaviour of In x Ga1? x As alloy on GaAs (001) and (110) substrates

Zhang, X.; Pashley, D. W.

doi:10.1007/bf00185931

Cited by 12 publications

(12 citation statements)

References 16 publications

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“…For In x Ga 1– x As shells grown on GaAs NW sidewalls, it has been shown that three-dimensional (3D) quantum dot (QD) formation readily occurs on {112} sidewalls but is suppressed on {110} sidewalls . Furthermore, for InAs growth on planar GaAs(110), two-dimensional (2D) layer growth is believed to always be favored over 3D growth. , We note that InAs QD growth has been observed for both planar surfaces and NW shells on AlAs(110). Interestingly, the growth of (Al,Ga)As shells around GaAs NW cores has been shown to also result in {112} facets forming at the edges of the {110} NW sidewalls .…”

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confidence: 85%

“…19 Furthermore, for InAs growth on planar GaAs(110), two-dimensional (2D) layer growth is believed to always be favored over 3D growth. 37,38 We note that InAs QD growth has been observed for both planar surfaces 39 and NW shells 16 on AlAs(110). Interestingly, the growth of (Al,Ga)As shells around GaAs NW cores has been shown to also result in {112} facets forming at the edges of the {110} NW sidewalls.…”

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confidence: 94%

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Anomalous Strain Relaxation in Core–Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth

et al. 2016

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Nanoscale substrates such as nanowires allow heterostructure design to venture well beyond the narrow lattice mismatch range restricting planar heterostructures, owing to misfit strain relaxing at the free surfaces and partitioning throughout the entire nanostructure. In this work, we uncover a novel strain relaxation process in GaAs/InGaAs core-shell nanowires that is a direct result of the nanofaceted nature of these nanostructures. Above a critical lattice mismatch, plastically relaxed mounds form at the edges of the nanowire sidewall facets. The relaxed mounds and a coherent shell grow simultaneously from the beginning of the deposition with higher lattice mismatches increasingly favoring incoherent mound growth. This is in stark contrast to Stranski-Krastanov growth, where above a critical thickness coherent layer growth no longer occurs. This study highlights how understanding strain relaxation in lattice mismatched nanofaceted heterostructures is essential for designing devices based on these nanostructures.

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confidence: 85%

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confidence: 94%

Anomalous Strain Relaxation in Core–Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth

et al. 2016

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“…11,12 While (In,Ga)As favors SK growth for a wide range of compositions and deposition conditions on GaAs(100), on other low-index GaAs surfaces such as (110) and (111), growth occurs via a 2D FM mode and misfit strain relaxes plastically. [13][14][15][16] Due to the low surface energy of GaAs(110), {110} facets are often present in self-assembled GaAs nanostructures such as nanowires and the growth of QDs on these structures is of interest for high brightness single photon sources. 17,18 Here we show that surfactants can provoke morphological phase transitions in strained layers, inducing the formation of 3D islands "on-demand".…”

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confidence: 99%

Quantum Dot Self-Assembly Driven by a Surfactant-Induced Morphological Instability

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et al. 2017

Phys. Rev. Lett.

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In strained heteroepitaxy, two-dimensional layers can exhibit a critical thickness at which three-dimensional islands self-assemble, relieving misfit strain at the cost of an increased surface area. Here we show that such a morphological phase transition can be induced on demand using surfactants. We explore Bi as a surfactant in the growth of InAs on GaAs(110), and find that the presence of surface Bi induces Stranski-Krastanov growth of 3D islands, while growth without Bi always favors 2D layer formation. Exposing a static two monolayer thick InAs layer to Bi rapidly transforms the layer into 3D islands. Density functional theory calculations reveal that Bi as well as Sb reduce the energetic cost of 3D island formation by modifying surface energies. These 3D nanostructures behave as optically active quantum dots. This work illustrates how surfactants can enable quantum dot self-assembly where it otherwise would not occur.

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“…In the case of GaAs NWs grown by the Ga-assisted vapor–liquid–solid (VLS) mode, the sidewall facets are of {11̅0} orientation . This poses challenges for the realization of advanced hierarchical structures, such as QDs embedded within NWs, , because two-dimensional (2D) layer growth is always favored on GaAs{110} surfaces and three-dimensional (3D) islands do not form by the Stranski–Krastanov (SK) mechanism. ,− The SK growth of InAs 3D islands on these surfaces has been observed after covering the facets with a thin AlAs layer but this is undesirable for most applications. , In contrast, GaAs NWs synthesized by Au-catalyzed growth typically exhibit {112̅} sidewall facets and the SK mechanism does occur on these surfaces, , however, the presence of Au can be undesirable for many applications.…”

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Self-Assembly of InAs Nanostructures on the Sidewalls of GaAs Nanowires Directed by a Bi Surfactant

et al. 2017

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Surface energies play a dominant role in the self-assembly of three dimensional (3D) nanostructures. In this letter, we show that using surfactants to modify surface energies can provide a means to externally control nanostructure self-assembly, enabling the synthesis of novel hierarchical nanostructures. We explore Bi as a surfactant in the growth of InAs on the {110} sidewall facets of GaAs nanowires. The presence of surface Bi induces the formation of InAs 3D islands by a process resembling the StranskiKrastanov mechanism, which does not occur in the absence of Bi on these surfaces. The InAs 3D islands nucleate at the corners of the {110} facets above a critical shell thickness and then elongate along 110 directions in the plane of the nanowire sidewalls. Exploiting this growth mechanism, we realize a series of novel hierarchical nanostructures, ranging from InAs quantum dots on single {110} nanowire facets to zig-zag shaped nanorings completely encircling nanowire cores. Photoluminescence spectroscopy and cathodoluminescence spectral line scans reveal that small surfactant-induced InAs 3D islands behave as optically active quantum dots. This work illustrates how surfactants can provide an unprecedented level of external control over nanostructure self-assembly. KEYWORDS: nanowire, quantum dot, bismuth, surfactant, GaAs, semiconductor 2The bottom-up self-assembly of semiconductor nanostructures is directed by energy minimization. As a result, many aspects of nanostructure self-assembly are intrinsic and therefore difficult to control externally. For example, nanostructures such as nanowires (NWs) and quantum dots (QDs) spontaneously form low-energy facets during their synthesis. In the case of GaAs NWs grown by the Ga-assisted vapor-liquid-solid (VLS) mode, the sidewall facets are of {110} orientation. 1 This poses challenges for the realization of advanced hierarchical structures, such as QDs embedded within NWs, 2,3 since two-dimensional (2D) layer growth is always favored on GaAs{110} surfaces and three-dimensional (3D) islands do not form by the StranskiKrastanov (SK) mechanism. 2,4-6 The SK growth of InAs 3D islands on these surfaces has been observed after covering the facets with a thin AlAs layer, but, this is undesirable for most applications. 2,7 In contrast, GaAs NWs synthesized by Au-catalyzed growth typically exhibit {112} sidewall facets and the SK mechanism does occur on these surfaces, 6,8 however, the presence of Au can be detrimental to NW optoelectronic properties. 9 We recently reported that the presence of surface Bi can induce the self-assembly of InAs 3D islands directly on planar GaAs(110) surfaces. 10 The Bi surfactant was shown to modify the surface energies, reducing the energetic cost of 3D island formation. Furthermore, in contrast to more common surface-segregating elements like Sb and Te, which have been shown to reduce adatom diffusion and consequently inhibit the formation of 3D islands, 11,12 Bi has been found to increase adatom diffusion. 13 This makes Bi of particular i...

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A comparison of strain relief behaviour of In x Ga1? x As alloy on GaAs (001) and (110) substrates

Cited by 12 publications

References 16 publications

Anomalous Strain Relaxation in Core–Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth

Anomalous Strain Relaxation in Core–Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth

Quantum Dot Self-Assembly Driven by a Surfactant-Induced Morphological Instability

Self-Assembly of InAs Nanostructures on the Sidewalls of GaAs Nanowires Directed by a Bi Surfactant

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