Growth and Field-Emission Properties of Vertically Aligned Cobalt Nanowire Arrays

Vila, Laurent; Vincent, P.; Pra, L. Dauginet-De; Pirio, G.; Minoux, E.; Gangloff, L.; Demoustier‐Champagne, Sophie; Sarazin, N.; Ferain, Etienne; Legras, Roger; Piraux, Luc; Legagneux, Pierre

doi:10.1021/nl0499239

Cited by 146 publications

(89 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, we define the turn-on field as the electric field required to produce a current density of 10 lA cm ±2 . The result shows that the tungsten oxide nanowire networks have a turn-on field of 13.85 MV m ±1 ; this value is comparable to the values reported for vertically aligned Co nanowires, [24] RuO 2 nanorods, [25] IrO 2 nanorods, [26] and ZnO nanowires. [27] The inset to Figure 6 displays the corresponding Fowler± Nordheim (FN) plot; the variation of ln(J/E 2 ) versus 1/E exhibits an approximately linear behavior, indicating that field emission from the tungsten oxide nanowire networks is a barrier-tunneling process.…”

supporting

confidence: 71%

Three‐Dimensional Tungsten Oxide Nanowire Networks

Zhou¹,

Ding²,

Deng³

et al. 2005

Advanced Materials

339

260

View full text Add to dashboard Cite

Among transition metal oxides, tungsten oxides (WO 3±d )are of great interest and have been investigated extensively owing to their promising physical and chemical properties.[1±6] With outstanding electrochromic, optochromic, and gaschromic properties, tungsten oxides have been used to construct flatpanel displays, photoelectrochromic ªsmartº windows, optical modulation devices, write±read±erase optical devices, gas sensors, humidity and temperature sensors, and so forth.[1±5]Recently, some non-stoichiometric tungsten oxides have attracted considerable attention for their interesting electronic properties, especially superconductivity and charge-carrying abilities. [7] It is well known that nanostructures have unique chemical and physical properties and can be used as elementary units of optoelectronic devices.[8±10] The synthesis of one-dimensional (1D) nanostructures and the assembly of these nanometer-scale building blocks to form ordered superstructures or complex functional architectures offer great opportunities for exploring their novel properties and for the fabrication of nanodevices.[11±13] Thus far, several techniques for the preparation of 1D tungsten oxide nanostructures have been developed. [6,14±17] Although the synthesis of tungsten oxide ªmicro-treesº has been reported, [18] the growth of tungsten oxide nanowire networks remains challenging. In this paper we have successfully synthesized three-dimensional (3D) tungsten oxide nanowire networks using a thermal evaporation approach. Transmission electron microscopy (TEM) investigation indicates that the WO 3±d nanowires have a cubic structure; this is confirmed by X-ray diffraction results (see Supporting Information). Growth along the six equivalent á100ñ directions forms an intersectant 3D network structure. The mechanism that drives such growth is suggested to be the existence of ordered planar oxygen vacancies in the (100) and (001) planes parallel to the [010] growth direction. Field-emission characteristics of these nanowire networks have also been measured. The tungsten oxide nanowire networks were synthesized by the thermal evaporation of W powders in the presence of oxygen. The scanning electron microscopy (SEM) images in Figure 1 show the typical morphology of the as-synthesized products. The high yield of the nanowire networks can be observed from the low-magnification SEM image in Figure 1a. The high-magnification SEM image in Figure 1b clearly demonstrates the shape of the 3D nanowire network. The 3D network is constructed of nanowires with widths ranging from 10 to 180 nm. The WO 3±d nanowires show a polygonal shape and intercross with each other to form the 3D network. The branches are along three perpendicular directions. Notably, there is no obvious stem in the network, making this structure different from previously reported networks and tree-like nanostructures. [11,13,18] Energy-dispersive X-ray spectroscopy (EDS) indicates the exclusive presence of W and O in the sample. Figure 2a shows a typical TEM image of a broken WO 3±d n...

show abstract

supporting

confidence: 71%

Three‐Dimensional Tungsten Oxide Nanowire Networks

Zhou¹,

Ding²,

Deng³

et al. 2005

Advanced Materials

339

260

View full text Add to dashboard Cite

show abstract

“…Evanescent nanometry can effectively replace AFM as a means of accurately measuring length in the z axis, provided that other means are used to ensure a vertical displacement of the molecule. This can be done by using magnetic tweezers (5) or a variety of other nanofabricated substrates that can provide a template in the z-axis direction (16). These approaches can be used to vertically align actin filaments or microtubules to observe the z-axis movement of fluorescently labeled molecular motors at a much higher resolution than currently possible.…”

Section: Resultsmentioning

confidence: 99%

Simultaneous atomic force microscope and fluorescence measurements of protein unfolding using a calibrated evanescent wave

Sarkar

Robertson

Fernández

2004

Proc. Natl. Acad. Sci. U.S.A.

117

View full text Add to dashboard Cite

Fluorescence techniques for monitoring single-molecule dynamics in the vertical dimension currently do not exist. Here we use an atomic force microscope to calibrate the distance-dependent intensity decay of an evanescent wave. The measured evanescent wave transfer function was then used to convert the vertical motions of a fluorescent particle into displacement (SD ‫؍‬ <1 nm). We demonstrate the use of the calibrated evanescent wave to resolve the 20.1 ؎ 0.5-nm step increases in the length of the small protein ubiquitin during forced unfolding. The experiments that we report here make an important contribution to fluorescence microscopy by demonstrating the unambiguous optical tracking of a single molecule with a resolution comparable to that of an atomic force microscope.

show abstract

“…Recent progress in sample growth has allowed to create free-standing nanowires which are grown perpendicular to their substrate (for example [44][45][46]. While it is outside the scope of this work to investigate these systems in detail, we comment briefly on possible analytical approximations.…”

Section: Perpendicular Nanowiresmentioning

confidence: 99%

Joule heating in nanowires

et al. 2011

View full text Add to dashboard Cite

We study the effect of Joule heating from electric currents flowing through ferromagnetic nanowires on the temperature of the nanowires and on the temperature of the substrate on which the nanowires are grown. The spatial current density distribution, the associated heat generation, and diffusion of heat is simulated within the nanowire and the substrate. We study several different nanowire and constriction geometries as well as different substrates: (thin) silicon nitride membranes, (thick) silicon wafers, and (thick) diamond wafers. The spatially resolved increase in temperature as a function of time is computed.For effectively three-dimensional substrates (where the substrate thickness greatly exceeds the nanowire length), we identify three different regimes of heat propagation through the substrate: regime (i), where the nanowire temperature increases approximately logarithmically as a function of time. In this regime, the nanowire temperature is well-described analytically by You et al.[ APL89, 222513 (2006)]. We provide an analytical expression for the time tc that marks the upper applicability limit of the You model. After tc, the heat flow enters regime (ii), where the nanowire temperature stays constant while a hemispherical heat front carries the heat away from the wire and into the substrate. As the heat front reaches the boundary of the substrate, regime (iii) is entered where the nanowire and substrate temperature start to increase rapidly.For effectively two-dimensional substrates (where the nanowire length greatly exceeds the substrate thickness), there is only one regime in which the temperature increases logarithmically with time for large times, before the heat front reaches the substrate boundary. We provide an analytical expression, valid for all pulse durations, that allows one to accurately compute this temperature increase in the nanowire on thin substrates.

show abstract

Growth and Field-Emission Properties of Vertically Aligned Cobalt Nanowire Arrays

Cited by 146 publications

References 15 publications

Three‐Dimensional Tungsten Oxide Nanowire Networks

Three‐Dimensional Tungsten Oxide Nanowire Networks

Simultaneous atomic force microscope and fluorescence measurements of protein unfolding using a calibrated evanescent wave

Joule heating in nanowires

Contact Info

Product

Resources

About