Direct observation of interface and nanoscale compositional modulation in ternary III-As heterostructure nanowires

Venkatesan, Sriram; Madsen, Morten Hannibal; Schmid, H.; Krogstrup, Peter; Johnson, Erik; Scheu, Christina

doi:10.1063/1.4818338

Cited by 16 publications

(10 citation statements)

References 35 publications

(64 reference statements)

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“…Axial NW HSs of III–V compounds have been elaborated with both Au and group III metal catalysts and through either group III or group V intermixing. It is generally recognized that Au-catalyzed NW heterointerfaces are broader when based on the group III intermixing (InGaAs ,, ) because of a high solubility of group III metals in liquid Au. The interfacial abruptness improves in group V based HSs within Au-catalyzed GaAsP or InAsP NWs due to a much lower solubility of highly volatile As and P species in Au (however, it does not seem to be the case in Au-catalyzed InAsSb NWs).…”

Section: Introductionmentioning

confidence: 99%

Factors Influencing the Interfacial Abruptness in Axial III–V Nanowire Heterostructures

Dubrovskiı̆

Sibirev

2016

Crystal Growth & Design

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We present a model that allows for self-consistent description of the interfacial abruptness in axial III−V nanowire heterostructures grown by the vapor−liquid−solid method. Our approach is based on the regular growth concept and avoids using chemical potentials of complex liquid alloys. The model applies equally well to Au-catalyzed or self-catalyzed growth and heterostructures based on either group III or V intermixing. We unravel the major factors influencing the nanowire composition and formulate general recipes for improving the interfacial abruptness. We show that the interfaces become sharper with the growth interrupts at the flux commutation, while the interfacial abruptness of group III based, Au-catalyzed heterostructures should be significantly improved by increasing the group V flux. Quite interestingly, there is a possibility to obtain a nanowire heterostructure by just sharply changing the flux of the other group element.

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Section: Introductionmentioning

confidence: 99%

Factors Influencing the Interfacial Abruptness in Axial III–V Nanowire Heterostructures

Dubrovskiı̆

Sibirev

2016

Crystal Growth & Design

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“…For example, the thermodynamic affinity of In is greater than that of Ga in the Au nanoparticle. Therefore, it is easier to expunge the Ga by increasing the In concentration in the droplet, while expunging the In out of the droplet by increasing the Ga concentration is more difficult [228]. This could cause the different abruptness of different element switch sequences (figures 14(a)-(c)) [225].…”

Section: Axial Junctionmentioning

confidence: 99%

Elongated nanostructures for radial junction solar cells

et al. 2013

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In solar cell technology, the current trend is to thin down the active absorber layer. The main advantage of a thinner absorber is primarily the reduced consumption of material and energy during production. For thin film silicon (Si) technology, thinning down the absorber layer is of particular interest since both the device throughput of vacuum deposition systems and the stability of the devices are significantly enhanced. These features lead to lower cost per installed watt peak for solar cells, provided that the (stabilized) efficiency is the same as for thicker devices. However, merely thinning down inevitably leads to a reduced light absorption. Therefore, advanced light trapping schemes are crucial to increase the light path length. The use of elongated nanostructures is a promising method for advanced light trapping. The enhanced optical performance originates from orthogonalization of the light's travel path with respect to the direction of carrier collection due to the radial junction, an improved anti-reflection effect thanks to the three-dimensional geometric configuration and the multiple scattering between individual nanostructures. These advantages potentially allow for high efficiency at a significantly reduced quantity and even at a reduced material quality, of the semiconductor material. In this article, several types of elongated nanostructures with the high potential to improve the device performance are reviewed. First, we briefly introduce the conventional solar cells with emphasis on thin film technology, following the most commonly used fabrication techniques for creating nanostructures with a high aspect ratio. Subsequently, several representative applications of elongated nanostructures, such as Si nanowires in realistic photovoltaic (PV) devices, are reviewed. Finally, the scientific challenges and an outlook for nanostructured PV devices are presented.

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“…Formation of semiconductor nanowires from a nanoscale liquid droplet by the vapor–liquid–solid process is an important example of complex, multiphase crystal growth. This process allows for the formation of anisotropic crystals with highly precise selectivity for crystal phase, composition, , morphology, , and properties . While the nucleation step and its role in material properties have been investigated in detail, − less attention has been paid to the overall stability of the process and the conditions required for the droplet to remain at the top of the nanowire during growth. , This condition is essential to prevent nanowire kinking and spontaneous change of growth orientation, , displacement of the droplet from the nanowire, and failure of the growth process itself .…”

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confidence: 99%

Limits of III–V Nanowire Growth Based on Droplet Dynamics

Tornberg

Maliakkal

Jacobsson

et al. 2020

J. Phys. Chem. Lett.

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Crystal growth of III-V semiconductor nanowires assisted by a liquid particle/droplet occurs at the solid-liquid interface. This makes the stability of a droplet on the top of a nanowire crucial for successful nanowire growth. Using in-situ transmission electron microscopy together with theoretical analysis of the capillary forces involved, we conclude that truncation of the solid-liquid interface extend the stability range for a droplet in contact with the nanowire top interface. This provides insights to the limits of nanowire growth and is used to experimentally estimate the surface energy of the wurtzite {1 1 2 0} facet of GaAs.Epitaxial crystal growth of semiconductor nanowires assisted by a liquid-particle relies, in a simple perspective, on two fundamental principles: nucleation of material, and a liquid covering the growth front. As in many cases of crystal growth from a melt, the wetting angle, or the contact angle between the growing crystal and the melt, is of importance for crystal formation [1,2]. For nanowires grown by the vapor-liquid-solid (VLS) mechanism, a fundamental stability criterion for having a droplet at the nanowire top has been proposed by Nebol'sin and Shchetinin[3] based on ex-situ observations and earlier theoretical work [4][5][6].Since their report on this stability limit, several experimental[7-11] and theoretical [12][13][14][15] investigations of nanowire growth focusing on the wetting properties of the liquid metal catalyst have been reported, often with focus on its influence on nucleation [8,9] rather than the droplet wetting dynamics. Still, this Nebol'sin-Shchetinin stability criterion remains generally accepted, perhaps due to the simplicity of the model. The Nebol'sin-Shchetinin model predicts an upper bound for having a droplet on the top nanowire facet by relating the ratio of the surface energies of the solid and liquid phases in contact with the vapor (γ sv and γ lv ) to the wetting angle and tapering of the nanowire[3].Although the model is widely accepted, it has important limitations: for instance growth of self-assisted GaAs [16] and InAs [17] have been extensively reported, although the relevant surface energy ratios are in these cases greater than the predicted upper bound (γ sv /γ lv ∼ 2 compared to √ 2 for un-tapered nanowires[3]). A limitation of the existing model is the assumption that the interface between droplet and nanowire is flat, which, according to experimental results [8,9,18], is not always the case during growth. These experimental reports have shown the formation of a truncation of the top nanowire facet during growth,

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Direct observation of interface and nanoscale compositional modulation in ternary III-As heterostructure nanowires

Cited by 16 publications

References 35 publications

Factors Influencing the Interfacial Abruptness in Axial III–V Nanowire Heterostructures

Factors Influencing the Interfacial Abruptness in Axial III–V Nanowire Heterostructures

Elongated nanostructures for radial junction solar cells

Limits of III–V Nanowire Growth Based on Droplet Dynamics

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