Phase Selection Enabled Formation of Abrupt Axial Heterojunctions in Branched Oxide Nanowires

Gao, Jing; Lebedev, Oleg I.; Turner, Stuart; Li, Yong Feng; Lu, Yun; Feng, Yuan Ping; Boullay, Philippe; Prellier, W.; Tendeloo, Gustaaf Van; Wu, Tom

doi:10.1021/nl2035089

Cited by 28 publications

(44 citation statements)

References 51 publications

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“…Moreover, several recent studies about the ITO nanowires reflect the importance of not only applications based on excellent metallic conductivity with the transparency but also growth mechanism itself272829. Studies of ITO nanowire growth with Au or Au-Cu nanodots as catalysts clearly show the role of Sn during the VLS process2728. However, the growth behavior will differ when a self-catalyst is used, because the atomic diffusion and reactivity of In and Sn in Au or Au-Cu matrix will be different from those in the pure self-catalyst.…”

Section: Resultsmentioning

confidence: 99%

Growth mechanism of metal-oxide nanowires synthesized by electron beam evaporation: A self-catalytic vapor-liquid-solid process

Lee

2014

Sci Rep

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We report the growth mechanism of metal oxide nanostructures synthesized by electron beam evaporation. The condensed electron beam can easily decompose metal oxide sources that have a high melting point, thereby creating a self-catalytic metal nanodot for the vapor-liquid-solid process. The metal oxide nanostructures can be grown at a temperature just above the melting point of the self-catalyst by dissolving oxygen. The morphology of nanostructures, such as density and uniformity, strongly depends on the surface energy and surface migration energy of the substrate. The density of the self-catalytic metal nanodots increased with decreasing surface energies of the substrate due to the perfect wetting phenomenon of the catalytic materials on the high surface energy substrate. However, the surfaces with extremely low surface energy had difficulty producing the high density of self-catalyst nanodot, due to positive line tension, which increases the contact angle to >180°. Moreover, substrates with low surface migration energy, such as single layer graphene, make nanodots agglomerate to produce a less-uniform distribution compared to those produced on multi-layer graphene with high surface migration energy.

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Section: Resultsmentioning

confidence: 99%

Growth mechanism of metal-oxide nanowires synthesized by electron beam evaporation: A self-catalytic vapor-liquid-solid process

Lee

2014

Sci Rep

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“…† In previous works, ISO phases have been found as the secondary phase. 24,26 Therefore, the physical properties of ISO single phases have never been measured to date. We measured the transport properties of fabricated ISO single crystalline nanowires by utilizing the measurement system, which has been reported elsewhere.…”

Section: Resultsmentioning

confidence: 99%

“…Note that these nanowires are entirely composed of the metastable ISO crystal phase, which is in sharp contrast to previous reports that showed the partial ISO crystal phase within nanowires. 24,26 The detailed microstructural analysis of ISO nanowires can be seen in ESI - Fig. S1.…”

Section: Introductionmentioning

confidence: 99%

A flux induced crystal phase transition in the vapor–liquid–solid growth of indium-tin oxide nanowires

et al. 2014

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Single crystalline metal oxide nanowires formed via a vapor-liquid-solid (VLS) route provide a platform not only for studying fundamental nanoscale properties but also for exploring novel device applications. Although the crystal phase variation of metal oxides, which exhibits a variety of physical properties, is an interesting feature compared with conventional semiconductors, it has been difficult to control the crystal phase of metal oxides during the VLS nanowire growth. Here we show that a material flux critically determines the crystal phase of indium-tin oxide nanowires grown via the VLS route, although thermodynamical parameters, such as temperature and pressure, were previously believed to determine the crystal phase. The crystal phases of indium-tin oxide nanowires varied from the rutile structures (SnO2), the metastable fluorite structures (InxSnyO3.5) and the bixbyite structures (Sn-doped In2O3) when only the material flux was varied within an order of magnitude. This trend can be interpreted in terms of the material flux dependence of crystal phases (rutile SnO2 and bixbyite In2O3) on the critical nucleation at the liquid-solid (LS) interface. Thus, precisely controlling the material flux, which has been underestimated for VLS nanowire growths, allows us to design the crystal phase and properties in the VLS nanowire growth of multicomponent metal oxides.

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“…In the zoom-in TEM image of the trijunction of growth seed, NW and substrate (Figure 4b), the NW/NP interface forming an inclined angle of approximately 54.7°with respect to the substrate surface was identified as the ITO (100) plane based on the crystallographic relationship, which is consistent with our previous observations. 36,37 The axial cross-sectional image in Figure 4c shows that the NW sidewalls are composed of high-index facets. The TEM image (Figure 4d) and the corresponding fast Fourier transform (FFT) patterns ( Figure 4e) taken near the NW/substrate interface confirm the expected good epitaxial relationship between the ITO NW and the YSZ substrate.…”

mentioning

confidence: 99%

Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

Shen

Chen

et al. 2016

Nano Lett.

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Epitaxy-enabled bottom-up synthesis of self-assembled planar nanowires via the vapor–liquid–solid mechanism is an emerging and promising approach toward large-scale direct integration of nanowire-based devices without postgrowth alignment. Here, by examining large assemblies of indium tin oxide nanowires on yttria-stabilized zirconia substrate, we demonstrate for the first time that the growth dynamics of planar nanowires follows a modified version of the Gibbs–Thomson mechanism, which has been known for the past decades to govern the correlations between thermodynamic supersaturation, growth speed, and nanowire morphology. Furthermore, the substrate orientation strongly influences the growth characteristics of epitaxial planar nanowires as opposed to impact at only the initial nucleation stage in the growth of vertical nanowires. The rich nanowire morphology can be described by a surface-energy-dependent growth model within the Gibbs–Thomson framework, which is further modulated by the tin doping concentration. Our experiments also reveal that the cutoff nanowire diameter depends on the substrate orientation and decreases with increasing tin doping concentration. These results enable a deeper understanding and control over the growth of planar nanowires, and the insights will help advance the fabrication of self-assembled nanowire devices.

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Phase Selection Enabled Formation of Abrupt Axial Heterojunctions in Branched Oxide Nanowires

Cited by 28 publications

References 51 publications

Growth mechanism of metal-oxide nanowires synthesized by electron beam evaporation: A self-catalytic vapor-liquid-solid process

Growth mechanism of metal-oxide nanowires synthesized by electron beam evaporation: A self-catalytic vapor-liquid-solid process

A flux induced crystal phase transition in the vapor–liquid–solid growth of indium-tin oxide nanowires

Gibbs–Thomson Effect in Planar Nanowires: Orientation and Doping Modulated Growth

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