Nanogap Electrodes

Li, Tao; Hu, Wenping; Zhu, Daoben

doi:10.1002/adma.200900864

Cited by 257 publications

(207 citation statements)

References 186 publications

(264 reference statements)

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“…Thus the changes in regions (1) and (2) shows the transient response when the nanowires reach the top of the template and commence to grow outside of the pore. The nanowire electrodeposition process was halted at stage (2). After the template was dissolved and the nanowires released SEM (Fig.…”

Section: Resultsmentioning

confidence: 99%

A Hybrid Approach to Fabricated Nanowire-Nanoparticle Composites of a Co-W Alloy and Au Nanoparticles

Vernickaite

Bubniene

Cesiulis

et al. 2016

J. Electrochem. Soc.

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Co-W nanowires were fabricated by pulsed electrodeposition from a citrate-glycine electrolyte onto rotating cylinder electrodes and into nanoporous polycarbonate membranes. The characterization of the electrodeposition conditions and alloy composition of electrodeposited Co-W alloy thin films were determined and used to guide conditions to electrodeposit the nanowires. Gold nanoparticles of 50 nm size were also added to the electrolyte and deposited during electrodeposition of the Co-W alloy nanowires, embedded within, and attached to the nanowire tip, introducing a novel procedure to attached nanoparticles onto nanowires. Nano-electrodes can be used for various sensing applications, and they can be easily integrated in micro-and nano-scale devices.1 The sensitivity of nano-electrodes depends on the diameter of electrode tip, and the highest sensitivity is observed by most electrochemical methods if the diameter of the working electrode tip is on the same order of the molecular species being detected. To this end, nano-gaping technology has been applied for the fabrication of nano-electrodes that are based on FIB and E-beam lithographic approaches, 2,3 including electrodeposition and/or chemical etching techniques. Gold-based 1D nanostructures (e.g., nanowires, gold nanoparticles) have been recognized as unique materials for electrical and optical sensing applications.5 Gold nanowires can provide high current densities, high signal to noise ratio and low double layer capacitance, 6 while surface plasmon resonance, often exploited with nanoparticles, can uniquely probe interactions of molecules at chemical surfaces and provide label-free bio detection. 5-8Gold nanoparticles (AuNPs) are excellent materials for functionalizing electrode surfaces.9,10 Functionalization can be achieved via the use of bi-functional chemical linking agents, mixing with the components of composite electrodes, covalent binding and others. Notably, gold nanoparticles alone have limited applications in sensing unless surface modification is performed. Careful selection and design of ligands strongly influence the sensitivity and selectivity of a sensor. 5,11 Gold nanoparticles can be synthesized by a citrate reduction method pioneered by Turkevich 12 and later advanced by Frens, 13 with a variety of modification's methods. 6,[14][15][16][17][18] The nanoparticle morphology is dependent upon chemical nanoparticle synthesis methods.Linking agents are typically applied in order to bind gold nanoparticles to surfaces of various substrates. 7,14,[19][20][21][22][23] Surface chemical modification and functionalization using linkers both are attractive methodologies because of highly active and selective layer formation, strong electrode intersectional binding, and changeable physical properties. However, there are a few important disadvantages if linkers are applied in order to design nano-electrodes: additional materials affect surface conductivity and can reduce it or lead to poor electrical contact, and they can shorten an electrode's applica...

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Section: Resultsmentioning

confidence: 99%

A Hybrid Approach to Fabricated Nanowire-Nanoparticle Composites of a Co-W Alloy and Au Nanoparticles

Vernickaite

Bubniene

Cesiulis

et al. 2016

J. Electrochem. Soc.

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“…3 In planar nanogap junctions an insulating spacer is produced by a poorly reproducible and low yield electromigration step which is accomplished with expensive nanofabrication tools. 21,39 Mechanically controllable break-junction devices, requiring controlled bending of a sample to open and close nanoscale gap, 21,40,41 is limited in scope with regards to the selection of materials, ease of fabrication and commercialization.…”

Section: Molecules Serve As a Device Element Not As A Physical Barriermentioning

confidence: 99%

Advantages of Prefabricated Tunnel Junction-Based Molecular Spintronics Devices

Tyagi

Friebe

Baker

2015

NANO

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Molecule-based devices may govern the advancement of the next generation's logic and memory devices. Molecules have the potential to be unmatched device elements as chemists can mass produce an endless variety of molecules with novel optical, magnetic and charge transport characteristics. However, the biggest challenge is to connect two metal leads to a target molecule (s) and develop a robust and versatile device fabrication technology that can be adopted for commercial scale mass production. This paper discusses distinct advantages of utilizing commercially successful tunnel junctions as a vehicle for developing molecular spintronics devices. We describe the use of a prefabricated tunnel junction with the exposed sides as a testbed for molecular device fabrication. On the exposed sides of a tunnel junction molecules are bridged across an insulator by chemically bonding with the two metal electrodes; sequential growth of metal-insulator-metal layers ensures that separation between two metal electrodes is controlled by the insulator thickness to the molecular device length scale. This paper highlights various attributes of tunnel junction-based molecular devices with ferromagnetic electrodes for making molecular spintronics devices. We strongly emphasize a need for close collaboration between chemists and magnetic tunnel junction (MTJ) researchers. Such partnerships will have a strong potential to develop tunnel junction-based molecular devices for futuristic areas such as memory devices, magnetic metamaterials, high sensitivity multi-chemical biosensors, etc.

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“…Electrode-nanogap-electrode structures, so-called nanogap electrodes 1 or electronic nanogaps 2 , are used in nanoelectronics, nanophotonics, plasmonics, nanopore sequencing, molecular electronics, and molecular sensing. They provide a powerful test-bed for mesoscopic physics [3][4][5][6][7] .…”

Section: Introductionmentioning

confidence: 99%

“…Accurately producing sub-5 nm wide gaps requires a patterning resolution of a few atomic layers, which is a great technological challenge even if only a few devices are to be realized 12 . Existing nanogap fabrication techniques include mask-defined etching processes 13 , layer-defined sacrificial etching processes 14 , material-growth processes 1,15 , self-assembly processes 7,16 , and the break junction (BJ) technique [17][18][19] . Each of these approaches suffers from severe drawbacks, including limited process control, limited dimensional accuracy, limited process scalability and risk of residual contaminants inside the nanogaps.…”

Section: Introductionmentioning

confidence: 99%

Design and fabrication of crack-junctions

2017

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Nanogap electrodes consist of pairs of electrically conducting tips that exhibit nanoscale gaps. They are building blocks for a variety of applications in quantum electronics, nanophotonics, plasmonics, nanopore sequencing, molecular electronics, and molecular sensing. Crack-junctions (CJs) constitute a new class of nanogap electrodes that are formed by controlled fracture of suspended bridge structures fabricated in an electrically conducting thin film under residual tensile stress. Key advantages of the CJ methodology over alternative technologies are that CJs can be fabricated with wafer-scale processes, and that the width of each individual nanogap can be precisely controlled in a range from o 2 to 4100 nm. While the realization of CJs has been demonstrated in initial experiments, the impact of the different design parameters on the resulting CJs has not yet been studied. Here we investigate the influence of design parameters such as the dimensions and shape of the notches, the length of the electrode-bridge and the design of the anchors, on the formation and propagation of cracks and on the resulting features of the CJs. We verify that the design criteria yields accurate prediction of crack formation in electrode-bridges featuring a beam width of 280 nm and beam lengths ranging from 1 to 1.8 μm. We further present design as well as experimental guidelines for the fabrication of CJs and propose an approach to initiate crack formation after release etching of the suspended electrode-bridge, thereby enabling the realization of CJs with pristine electrode surfaces.

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Nanogap Electrodes

Cited by 257 publications

References 186 publications

A Hybrid Approach to Fabricated Nanowire-Nanoparticle Composites of a Co-W Alloy and Au Nanoparticles

A Hybrid Approach to Fabricated Nanowire-Nanoparticle Composites of a Co-W Alloy and Au Nanoparticles

Advantages of Prefabricated Tunnel Junction-Based Molecular Spintronics Devices

Design and fabrication of crack-junctions

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