Two‐probe electrical measurements in transmission electron microscopes—Behavioral control of tungsten microwires

Costa, Pedro M. F. J.; Fang, Xiaosheng; Wang, Shiliang; He, Yuehui; Bando, Yoshio; Mitome, Masanori; Zou, Jin; Huang, Han; Golberg, Dmitri

doi:10.1002/jemt.20648

Cited by 18 publications

(12 citation statements)

References 26 publications

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“…[6a] For comparison, Table 1 lists the fundamental performance indicators for FE applications measured on our tungsten whiskers and some other potential materials. Consistent with the superior electrical properties of a single sub-micrometer-sized tungsten whisker reported recently, [17] it is clear that our tungsten whisker arrays, despite their sub-micrometer diameter, have demonstrated exceptional FE properties, which can be the key for practical applications. In summary, sub-micrometer-sized tungsten whisker arrays have been synthesized on Si, SiO 2 , and Al 2 O 3 substrates using a catalyst-free and template-free vapor-deposition process.…”

supporting

confidence: 74%

Structure and Field‐Emission Properties of Sub‐Micrometer‐Sized Tungsten‐Whisker Arrays Fabricated by Vapor Deposition

Wang

Fang

et al. 2009

Advanced Materials

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One-dimensional (1D) sub-micrometer/nanometer-scale materials have attracted great attention as a result of their unique properties and promising potential for a wide range of applications.[1] To date, a number of 1D materials, including carbon nanotubes (CNTs), [2] oxides (ZnO, [3] MoO x , [4] WO x [5] ), carbides (SiC, [6] W 2 C [7] ), nitrides (AlN, [8] GaN [9] ), and metals (Mo, [4a,10] W, [11] Co [12] ), have been comprehensively studied as candidates for field-emission (FE) applications. Among them, CNTs and oxide nanowires exhibited relatively low turn-on fields. However, the lack of adequate long-term and/or high-temperature FE stability and satisfactory mechanical properties has hindered their development in practical applications. The refractory metal tungsten, as the most important metallic material, has been used for FE applications (as cold and/or hot cathodes) for decades, not only because of its high electronic emissivity but also due to its exceptional thermal and chemical stabilities (such as the highest melting point, $3420 8C, and the lowest vapor pressure among all metals, its decent strength and rigidity at room and elevated temperatures, and its excellent corrosion resistance to metal and oxide vapors).[13] Presumably, 1D structures of metallic tungsten should be an ideal choice for FE applications.[11] In fact, previous studies have revealed that individual tungsten nanowires possess an ultrahigh fieldenhancement factor [11c,d] (two orders of magnitude higher than that of CNTs [2] ) and a high stability of the FE current density (at $10 6 A cm À2, a standard deviation of less than 1%, [11d] in contrast to 24% shown by individual multiwalled CNTs [2d] ). In the past few years, the techniques for the fabrication of tungsten nanowires or nanorods have been intensively developed. [11,14] Nevertheless, the controllable synthesis of 1D tungsten micrometer/nanometerscale structures for FE applications still remains a great challenge. For example, although high-temperature vapor deposition has been considered a promising process, [11e,14e] and comprehensively studied for synthesizing tungsten nanorod/nanowire arrays, how to control the configuration and crystalline structure of the products at the growth temperatures of $1500 8C is still unclear. In this Communication, we report an innovative, simple, and cost-effective vapor-deposition method for synthesizing submicrometer-sized tungsten-whisker arrays with ideal configuration and excellent FE properties. Figure 1a shows a scanning electron microscopy (SEM) image of a tungsten whisker array grown on a Si (111) substrate at 900 8C for 4 h. The synthesized whiskers have an average diameter of 180 nm (ranging from 80 to 300 nm) and a length of up to 20 mm. A high-magnification SEM image of a typical whisker (inset in Fig. 1a) shows that it is straight and has a hexagonal cross-section and pyramidal tip. Energy-dispersive spectroscopy (EDS) analyses of the whiskers reveal that they consist of pure elemental tungsten. Figure 1b is a ty...

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supporting

confidence: 74%

Structure and Field‐Emission Properties of Sub‐Micrometer‐Sized Tungsten‐Whisker Arrays Fabricated by Vapor Deposition

Wang

Fang

et al. 2009

Advanced Materials

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“…Mechanically cut Au wires and chemically etched W wires, 0.25 mm in diameter, were used as electrodes (in Au-Au or Au-W pairs). The etching procedure has been explained elsewhere 16,17 . An extended discussion of the factors guiding the response of Zn 0.92 Ga 0.08 S@ CNTs to electrical heating is given in Supplementary Methods.…”

Section: Methodsmentioning

confidence: 99%

Direct imaging of Joule heating dynamics and temperature profiling inside a carbon nanotube interconnect

et al. 2011

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understanding resistive (or Joule) heating in fundamental nanoelectronic blocks, such as carbon nanotubes, remains a major challenge, particularly in regard to their structural and thermal variations during prolonged periods of electrical stress. Here we show real-time imaging of the associated effects of Joule heating in the channel of carbon nanotube interconnects. First, electrical contacts to nanotubes entirely filled with a sublimable material are made inside a transmission electron microscope. on exposure to a high current density, resistive hotspots are identified on (or near) the contact points. These later migrate and expand along the carbon nanotube, as indicated by the localized sublimation of the encapsulated material. using the hotspot edges as markers, it is possible to estimate the internal temperature profiles of the nanotube. simple and direct, our method provides remarkable spatial and temporal insights into the dynamics of resistive hotspots and millisecond-paced thermal variations occurring inside nanoscaled tubular interconnects.

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“…The electropolished tungsten tips are covered with a tungsten oxide layer, but in UHV this layer can be sublimated away at 800 ı C by heating it with a field emission current [151]. Gold can also be electropolished, but the procedure normally leaves a nanometer contamination layer [152] thick as shown by Costa et al [152]. Figure 3.23a shows this contamination layer, and the cleanliness of the simple cutting technique is demonstrated in Fig.…”

Section: A Proper Electrical Contact For Temspmmentioning

confidence: 95%

Combining Scanning Probe Microscopy and Transmission Electron Microscopy

Nafari¹,

Angenete²,

Svensson

et al. 2010

Scanning Probe Microscopy in Nanoscience and Nanotechnology 2

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This chapter is a review of an in situ method where a scanning probe microscope (SPM) has been combined with a transmission electron microscope (TEM). By inserting a miniaturized SPM inside a TEM, a large set of open problems can be addressed and, perhaps more importantly, one may start to think about experiments in a new kind of laboratory, an in situ TEM probing laboratory, where the TEM is transformed from a microscope for still images to a real-time local probing tool. In this method, called TEMSPM, the TEM is used for imaging and analysis of a sample and SPM tip, while the SPM is used for probing of electrical and mechanical properties or for local manipulation of the sample. This chapter covers both instrumental and applicational aspects of TEMSPM. Abbreviations

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Two‐probe electrical measurements in transmission electron microscopes—Behavioral control of tungsten microwires

Cited by 18 publications

References 26 publications

Structure and Field‐Emission Properties of Sub‐Micrometer‐Sized Tungsten‐Whisker Arrays Fabricated by Vapor Deposition

Structure and Field‐Emission Properties of Sub‐Micrometer‐Sized Tungsten‐Whisker Arrays Fabricated by Vapor Deposition

Direct imaging of Joule heating dynamics and temperature profiling inside a carbon nanotube interconnect

Combining Scanning Probe Microscopy and Transmission Electron Microscopy

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