Sub‐5 nm Metal Nanogaps: Physical Properties, Fabrication Methods, and Device Applications

Yang, Yang; Gu, Changzhi; Li, Junjie

doi:10.1002/smll.201804177

Cited by 92 publications

(92 citation statements)

References 185 publications

(429 reference statements)

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“…As a demonstration for the material‐independent capability, Pt, Ti, Au, Nb, Al 2 O 3 , and TiO x NGEs were fabricated ( Figure ). The SEM images allow us to access the geometrical shape of the as‐fabricated NGEs, which resemble previously reported shapes, but exhibit additional advantages. For example, the electrode length is dynamically tunable depending on the nanosphere size.…”

supporting

confidence: 55%

mentioning

confidence: 99%

“…Motivated by the miniaturized development, nanogap electrodes (NGEs) with decreasing separations have attracted worldwide attention as important platforms for detecting various small molecules and as fundamental building blocks for constructing multifunctional molecular devices and systems . Sub‐5 nm NGEs have exhibited great superiority in many application fields, such as sensing, optical, molecular, and electronic devices . The gap separations decreasing from the nanometer down to the angstrom scale will revolutionize the existing nanogap‐related research and lead to valuable new physical phenomena such as nonlocal electromagnetic effects, quantum interference, nuclear spins, and electron tunneling, which can unlock the full potential of applications with high scientific and societal impact, including molecular electronics, quantum tunneling, plasmonic nano‐optics, and highly sensitive sequencing …”

mentioning

confidence: 99%

“…Despite their importance, fabrication of sub‐5 nm NGEs remains a great technological challenge . Existing NGE‐manufacturing methods can be typically classified into two strategies: physical methods based on planar nanofabrication techniques and chemical methods based on noble metal nanoparticles.…”

mentioning

confidence: 99%

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Direct Deposited Angstrom‐Scale Nanogap Electrodes with Macroscopically Measurable and Material‐Independent Capabilities for Various Applications

Li¹,

Wang²,

Zhang³

et al. 2019

Adv Materials Technologies

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effects, quantum interference, nuclear spins, and electron tunneling, which can unlock the full potential of applications with high scientific and societal impact, including molecular electronics, [4][5][6][7][8][9] quantum tunneling, [10,11] plasmonic nano-optics, [12][13][14][15][16][17] and highly sensitive sequencing. [18][19][20] Despite their importance, fabrication of sub-5 nm NGEs remains a great technological challenge. [1] Existing NGEmanufacturing methods can be typically classified into two strategies: physical methods based on planar nanofabrication techniques and chemical methods based on noble metal nanoparticles. Most chemical methods are suitable for creating sub-1 nm NGEs [11][12][13][14][15] but limited to a relatively narrow range of applications owing to the contamination induced by linker molecules, the shell-filled gaps, and/or the restrictions derived from metal nanoparticle size. Physical methods, including direct patterning techniques, [21][22][23] breaking-/cracking-based methods, [6][7][8][9][10][16][17][18][19][20][24][25][26][27][28] and controllable deposition, [29][30][31] are fundamentally limited by the basic planar nanofabrication techniques. Particularly, direct patterning techniques variously suffer from high equipment costs, low throughput, and poor scalability to large sizes. The breaking-/cracking-based methods are the most widely used but typically involve direct patterning techniques to predefine the wire pattern, a complex apparatus to induce external stimuli, or special materials (e.g., brittle films) to induce internal stress. Though breaking-based methods can be used to produce sub-1 nm NGEs, [6][7][8][9][10][16][17][18][19][20] the intrinsic obstacles mentioned above result in discrete and material-limited NGEs with the fractal facing electrode surface blocking the realization of large-scale complex systems. Controllable deposition [29][30][31] is relatively simple for large-scale fabrication, while the formed NGEs typically face limitations derived from large gap width, problematic rough surfaces, the solution environment, or/and contaminations from the shadow-mask fabrication process. However, simply continuing to improve existing NGE-fabricating methods is insufficient since each method has its own serious inherent defects. An innovative approach is urgently needed to address these issues and to promote the developments of NGEs-based applications.Here, we demonstrate macroscopically measurable and material-independent NGEs with angstrom-scale separations Nanogap electrodes (NGEs) with decreasing separations have received growing attention due to their potential in stimulating extensive applications with high scientific impact, including molecular electronics, quantum tunneling, plasmonic optics, and highly sensitive sequencing. Although various NGE-manufacturing methods have been developed and offer promising results, angstrom-scale NGEs have not been achieved without requiring sophisticated equipment, restricting materials or substrates, compromising mass-fabric...

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supporting

confidence: 55%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Direct Deposited Angstrom‐Scale Nanogap Electrodes with Macroscopically Measurable and Material‐Independent Capabilities for Various Applications

Li¹,

Wang²,

Zhang³

et al. 2019

Adv Materials Technologies

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“…Observed from CA curves in Figure 9f, the sub-5 nm Pd tetrahedrons exhibited a significantly slower current decay and higher current intensity than the other two catalysts over the entire duration, suggesting long-term durability. [41,42] 2) The high-quality tetrahedral structure endows larger surface area-to-volume ratio, thus providing a large number of accessible catalytic sites on surface area. Specifically, (1) the ultrasmall size of sub-5 nm Pd tetrahedrons is the most simple yet important feature to guarantee high atom utilization efficiency.…”

Section: Wwwsmall-journalcommentioning

confidence: 99%

Shape Control of Monodispersed Sub‐5 nm Pd Tetrahedrons and Laciniate Pd Nanourchins by Maneuvering the Dispersed State of Additives for Boosting ORR Performance

Zhang

Qiu

Chen

et al. 2020

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It is a great challenge to simultaneously control the size, morphology, and facets of monodispersed Pd nanocrystals under a sub-5 nm regime. Meanwhile, quantitative understanding of the thermodynamic and kinetic parameters to maneuver the shape evolution of nanocrystals in a one-pot system still deserves investigation. Herein, a systematic study of the density functional theory (DFT)-calculated adsorption energy, thermodynamic factors, and reduction kinetics on Pd growth patterns is reported by combining theory and experiments, with a focus on the dispersed state of additives. As pure models, monodispersed Pd tetrahedrons enclosed by (111) facets with a narrow size distribution of 4.9 ± 1 nm and a high purity approaching 98% can be obtained when using 1,1′-binaphthalene (C 20 H 14 ) +2NH 3 as additives. Specifically, laciniate Pd nanourchins (Pd LUs) can evolve via anisotropic growth when replacing additive with dose-consistent 1,1′-binaphthyl-2,2′-diamine (C 20 H 16 N 2 , two NH 2 binding in C 20 H 14 ). Catalytic investigations show that the sub-5 nm Pd tetrahedrons exhibit higher activity in both the oxygen reduction (E onset = 1.025 V, E 1/2 = 0.864 V) and formic acid oxidation reaction with respect to the Pd LUs and Pd black, which represents a great step for the development of well-defined Pd nanocrystals with size in the sub-5 nm regime as non-Pt electrocatalysts.

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Reliable Patterning, Transfer Printing and Post‐Assembly of Multiscale Adhesion‐Free Metallic Structures for Nanogap Device Applications

Chen

Shu

Feng

et al. 2020

Adv Funct Materials

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Patterning of metallic nanogaps with ultrasmall gap size on arbitrary substrates is of great importance for various applications in nanoelectronics, nanoplasmonics, and flexible optoelectronics. Common lithographic approaches suffer from limited resolution in defining ultrasmall nanogaps and restrictive available substrates for flexible and stretchable devices. In this work, a process portfolio to overcome the above limitations is proposed, enabling the fabrication of multiscale metallic nanogaps with reduced gap size on specific substrates for functional devices. The portfolio combines the recently developed sketch and peel lithography strategy, nanotransfer printing, and post‐mechanical assembly. Among the portfolio, the sketch and peel lithography strategy provides the unique capability to rapidly and reliably define multiscale adhesion‐free metallic nanostructures and nanogaps, which significantly facilitates the subsequent transfer printing process. Nanoplasmonic and nanoelectronic devices with ultrasmall nanogaps that are inaccessible with existing patterning approaches are fabricated to demonstrate the applicability of this fabrication strategy. The portfolio could also have potential for a variety of other applications in flexible and stretchable optics, electronics, and optoelectronics.

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Sub‐5 nm Metal Nanogaps: Physical Properties, Fabrication Methods, and Device Applications

Cited by 92 publications

References 185 publications

Direct Deposited Angstrom‐Scale Nanogap Electrodes with Macroscopically Measurable and Material‐Independent Capabilities for Various Applications

Direct Deposited Angstrom‐Scale Nanogap Electrodes with Macroscopically Measurable and Material‐Independent Capabilities for Various Applications

Shape Control of Monodispersed Sub‐5 nm Pd Tetrahedrons and Laciniate Pd Nanourchins by Maneuvering the Dispersed State of Additives for Boosting ORR Performance

Reliable Patterning, Transfer Printing and Post‐Assembly of Multiscale Adhesion‐Free Metallic Structures for Nanogap Device Applications

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