Determination of Size Effects during the Phase Transition of a Nanoscale Au-Si Eutectic

Kim, B. J.; Tersoff, J.; Wen, Cheng‐Yen; Reuter, M. C.; Stach, Eric A.; Ross, FM

doi:10.1103/physrevlett.103.155701

Cited by 59 publications

(73 citation statements)

References 16 publications

(26 reference statements)

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“…1a, it is considered that the silicon particles are periodically formed inside the spherical tip and released to the stem along the growth in length. These would imply that the contact angle y will follow a periodic oscillation consistent with the in situ TEM observation of Kim et al 19,22 and Wen et al 23 The correlation between Si particles formation with morphology oscillation as well as the precise periodicity shown in Fig. 1a all suggest that Si particles are not formed by random precipitation.…”

Section: Resultssupporting

confidence: 81%

“…In contrast, it is interesting that while 1D structures with periodic features (types d-g) are often observed in nanowires, such periodicities are rare in 1D whiskers with diameters of over tens of micrometres. While novel optoelectronic properties due to quantum confinement effects have drawn much attention [14][15][16][17][18] , there is less discussion on the possible nanometre size effects on the growth mechanisms of nanostructures 19 .…”

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confidence: 99%

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A surface curvature oscillation model for vapour–liquid–solid growth of periodic one-dimensional nanostructures

Wang

Cao

et al. 2015

Nat Commun

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While the vapour-liquid-solid process has been widely used for growing one-dimensional nanostructures, quantitative understanding of the process is still far from adequate. For example, the origins for the growth of periodic one-dimensional nanostructures are not fully understood. Here we observe that morphologies in a wide range of periodic one-dimensional nanostructures can be described by two quantitative relationships: first, inverse of the periodic spacing along the length direction follows an arithmetic sequence; second, the periodic spacing in the growth direction varies linearly with the diameter of the nanostructure. We further find that these geometric relationships can be explained by considering the surface curvature oscillation of the liquid sphere at the tip of the growing nanostructure. The work reveals the requirements of vapour-liquid-solid growth. It can be applied for quantitative understanding of vapour-liquid-solid growth and to design experiments for controlled growth of nanostructures with custom-designed morphologies.

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Section: Resultssupporting

confidence: 81%

mentioning

confidence: 99%

A surface curvature oscillation model for vapour–liquid–solid growth of periodic one-dimensional nanostructures

Wang

Cao

et al. 2015

Nat Commun

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“…There are very few experimental results that allow a direct comparison with theoretical results, and the work by Kim et al 20 on the Au-Si system is one of the few. In their study, spherical Au nano-particles ≈35 nm in diameter were continuously exposed to disilane (Si 2 H 6 ) gas, and imaged with a transmission electron microscope.…”

Section: Au-simentioning

confidence: 99%

Phase stability in nanoscale material systems: extension from bulk phase diagrams

et al. 2015

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Phase diagrams of multi-component systems are critical for the development and engineering of material alloys for all technological applications. At nano dimensions, surfaces (and interfaces) play a significant role in changing equilibrium thermodynamics and phase stability. In this work, it is shown that these surfaces at small dimensions affect the relative equilibrium thermodynamics of the different phases. The CALPHAD approach for material surfaces (also termed "nano-CALPHAD") is employed to investigate these changes in three binary systems by calculating their phase diagrams at nano dimensions and comparing them with their bulk counterparts. The surface energy contribution, which is the dominant factor in causing these changes, is evaluated using the spherical particle approximation. It is first validated with the Au-Si system for which experimental data on phase stability of spherical nano-sized particles is available, and then extended to calculate phase diagrams of similarly sized particles of Ge-Si and Al-Cu. Additionally, the surface energies of the associated compounds are calculated using DFT, and integrated into the thermodynamic model of the respective binary systems. In this work we found changes in miscibilities, reaction compositions of about 5 at%, and solubility temperatures ranging from 100-200 K for particles of sizes 5 nm, indicating the importance of phase equilibrium analysis at nano dimensions.

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“…This Al film is not totally consumed during the growth step, so that it also serves as base electrode for the solar cell. 18 However, it has been shown recently that phase diagrams at the nanoscale could be different from those corresponding to bulk materials, 19 so that VLS growth cannot be completely ruled out. 16 Since we grow our wires at ~ 550 °C (i.e., below 577 °C which is the Al-Si eutectic temperature) and without any pre-annealing treatment at a higher temperature, 17 growth should proceed via a vapor-solid-solid (VSS) mechanism.…”

Section: Those Cells Incorporate Anmentioning

confidence: 99%

Connecting wire-based solar cells without any transparent conducting electrode

et al. 2016

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Electronic supplementary information available: growth, electrical and structural characterizations of the p-i-n and NiSi x wires, details about the band diagram, the evaluation of series resistances and the effective area of the device. Abstract:In order to reduce substrate costs and increase light absorption, solar cells based on semiconductor wire arrays are currently being actively studied. Whether built with Si, InP or other semiconductor materials, wire-based cells invariably use a transparent conductive coating for one of the electrodes, which complicates processing and does not contribute to reduce the overall cost of the cell. Here, we propose a totally novel connection process, where the transparent conductive electrode is replaced by an array of in situ-grown metallic nanowires. During their growth, those metallic nanowires randomly contact core-shell p-i-n Si wires previously synthesized by chemical vapor deposition. We demonstrate the feasibility of this new random connection concept by using a coplanar solar cell design with interdigitated base and emitter contacts. We obtain a high fill factor of ~ 74% and efficiencies of 4.5% with only 33% of the surface covered by p-i-n Si wires.

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Determination of Size Effects during the Phase Transition of a Nanoscale Au-Si Eutectic

Cited by 59 publications

References 16 publications

A surface curvature oscillation model for vapour–liquid–solid growth of periodic one-dimensional nanostructures

A surface curvature oscillation model for vapour–liquid–solid growth of periodic one-dimensional nanostructures

Phase stability in nanoscale material systems: extension from bulk phase diagrams

Connecting wire-based solar cells without any transparent conducting electrode

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