Tungsten nanowires and their field electron emission properties

Lee, Yun Hi; Choi, C.; Jang, Yoonsun; Kim, Eun Kyu; Ju, Byeong Kwon; Min, Nam Ki; Ahn, Jin Ho

doi:10.1063/1.1490625

Cited by 156 publications

(76 citation statements)

References 25 publications

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“…[12] W materials can be produced with various dimensions; 1D W nanowires have been found in particular to have useful electrical properties, such as efficient field-electron emission in a moderate electric field. [13] Although 1D…”

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confidence: 98%

A Novel Heteronanostructure System: Hierarchical W Nanothorn Arrays on WO₃ Nanowhiskers

2006

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The assembly of 1D nanostructures in the fabrication of nanoelectronic and nanophotonic devices is currently attracting significant attention. In particular, semiconductor and metal nanowires or nanorods are considered to be important building blocks in the fabrication of future nanodevices. Various types of nanowire heterostructures have been reported, including core/shell [1] and core/multishell nanocable structures, [2] coaxial nanowire heterojunctions, [3] epitaxial nanorod heterostructures, [4] and hierarchical heterostructures.[ [5g]Nanorods of transition metal oxides, such as WO 3, which have large surface areas and a high-aspect-ratio structure, are promising candidates for a vast range of applications including gas sensors, [6] photocatalysts, [7] electrochromic devices, [8] field-emission devices, [9] and solar-energy devices.[10] Because of the distinctive and promising properties of WO 3 , as-synthesized nanorods may also serve as functional building blocks in the fabrication of 3D nanostructures or multifunctional heteronanostructures. Recently Zhou et al. demonstrated the 3D growth of WO 3 nanowire networks using a thermal evaporation method.[11]W is a metal with a fairly low resistivity and a near-ideal midgap work function, and can be produced with a high refractivity through high-temperature processes. W can be used in metal gates in applications of complementary metal oxide semiconductor (CMOS) technology in nanodevices smaller than 100 nm.[12] W materials can be produced with various dimensions; 1D W nanowires have been found in particular to have useful electrical properties, such as efficient field-electron emission in a moderate electric field.[13] Although 1Dnanostructures of W and WO 3 have been studied extensively, few studies of W/WO 3 heteronanostructures have been reported.In this communication, we report the fabrication of a novel hierarchical heteronanostructure: single-crystal W nanothorns grown on WO 3 nanowhiskers (hereafter these heteronanostructures will be referred to as WWOs). In this WWO nanostructure, the WO 3 nanowhiskers were coated with thin W layers and W nanothorns grew on them. We used a two-step evaporation process to fabricate the hierarchical WWOs.In the first step, WO 3 nanowhiskers were deposited on a W plate by heating WO 3 powder at 1100°C on the substrate. Then, a mixture of WO 3 and graphite powder was used as the source material for the growth of the W nanothorns on the asprepared WO 3 nanowhiskers. Si powder was also heated with the substrate at 1100°C. We used the carbothermal reduction of WO 3 (WO 3 + C → WO x + CO 3-x ; x = 1-2) [14] and were able to expedite the further reduction of WO x species by using Si (WO x + Si → W + SiO x ) to produce W vapor. It is well known that W can be grown by Si reduction of W compounds.[15] The resulting W vapor was deposited on the WO 3 nanowhiskers to produce the WWO heteronanostructure. Our method for growing W nanomaterials is different to that used in previous studies: the thermal-heating of W films was the previ...

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confidence: 98%

A Novel Heteronanostructure System: Hierarchical W Nanothorn Arrays on WO₃ Nanowhiskers

2006

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“…Compared to semiconducting nanowires such as ZnO [6] or GaN [7], the metal-nanowire tip would be advantageous in terms of electric conductivity, which significantly lowers the driving voltage of FE. Experimentally, FE tips based on copper [5], tungsten [8], and gold [9] nanowires have been fabricated with appreciable emission performances. In spite of the accumulating experimental data, the theoretical understanding of FE for metal nanowires has not been elaborated much.…”

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confidence: 99%

Field emission of metal nanowires studied by first-principles methods

Lee¹,

Lee²,

Ihm³

et al. 2007

Nanotechnology

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We study the field-emission properties of an ultrathin silver nanowire using first-principles methods. The simulation and analysis of the field emission are carried out based on density-functional theory using a localized basis scheme. Through the explicit time evolution of wavefunctions, we obtain the emission currents and spatial distributions of emitted electrons from a silver nanowire. In contrast to carbon nanotubes, the localized states are not found. Instead, pronounced emission currents are observed for s-like extended states that are free of nodes in a plane normal to the field direction, and the total emission currents of a silver nanowire are found to be significantly larger than those of carbon nanotubes. A quantum-mechanical analysis is presented to explain the observed current enhancement. On the other hand, an ultrathin gold nanowire gives much smaller emission currents than the silver nanowire due to a larger work function.

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“…Whilst the power used was an order of magnitude larger than that for the commercial available system, this proof of concept does demonstrate that field emission from CNTs may find an application as a sustainable source of environmentally friendly lightening. Whilst carbon nanotubes have attracted the most attention electron emission has also been observed from a wide range of nanotube materials including SiC nanowires (Wong et al, 1999), Cu 2 S nanowires (Chen et al, 2002), W nanowires (Lee et al, 2002) and nanobelts of MoO 3 (Li et al, 2002).…”

Section: Controlling Inhomogeneity To Nanotip Cathodesmentioning

confidence: 99%

Engineering the next generation of large-area displays: prospects and pitfalls

Carey

2003

Philosophical Transactions of the Royal Society of London. Seri

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Considerable effort is currently been expounded into the development and improvement of the myriad of display technologies that have come to the market place. In this paper several key questions are addressed in the development of the future generation of large area field emissionbased displays based upon semiconducting amorphous carbon thin films and carbon nanotubes. The development of carbon based cathodes has to date proceeded along empirical lines with attempts to correlate the variation of field emission characteristics with changes in deposition or post deposition processing parameters, often without a full explanation being forthcoming. In addition, there have been incidents of incorrect interpretation of some of the results due to a lack of an appreciation of the significant differences between the different types of amorphous carbon film that exist. It is only recently that a fuller understanding of the different electron emission mechanisms has begun to emerge through an understanding of the roles played by the electrical and structural inhomogeneity at a nanometer level. This 'intrinsic dielectric inhomogeneity' is shown to possess some remarkable electronic properties which also has important consequences for extrinsic inhomogeneous nanometer systems such as carbon nanotube (CNT) and CNT-polymer composite based displays.The future outlook for broad area displays based upon amorphous carbon and carbon nanotubes is also addressed.

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Tungsten nanowires and their field electron emission properties

Cited by 156 publications

References 25 publications

A Novel Heteronanostructure System: Hierarchical W Nanothorn Arrays on WO₃ Nanowhiskers

A Novel Heteronanostructure System: Hierarchical W Nanothorn Arrays on WO₃ Nanowhiskers

Field emission of metal nanowires studied by first-principles methods

Engineering the next generation of large-area displays: prospects and pitfalls

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Tungsten nanowires and their field electron emission properties

Cited by 156 publications

References 25 publications

A Novel Heteronanostructure System: Hierarchical W Nanothorn Arrays on WO3 Nanowhiskers

A Novel Heteronanostructure System: Hierarchical W Nanothorn Arrays on WO3 Nanowhiskers

Field emission of metal nanowires studied by first-principles methods

Engineering the next generation of large-area displays: prospects and pitfalls

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Product

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A Novel Heteronanostructure System: Hierarchical W Nanothorn Arrays on WO₃ Nanowhiskers

A Novel Heteronanostructure System: Hierarchical W Nanothorn Arrays on WO₃ Nanowhiskers