Field emission from carbon nanotube fibers in varying anode-cathode gap with the consideration of contact resistance

Zhang, Peng; Fairchild, Steven B.; Back, Tyson C.; Luo, Yuan

doi:10.1063/1.5008995

Cited by 41 publications

(24 citation statements)

References 38 publications

(42 reference statements)

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“…The emission current was close to that of a single nanotube (0.1-10 µA vs. 0.1-1 µA) but at a higher bias voltage (200 V vs. 80 V) [80]. Research into this precursory film idea has been stopped for the next few years because of weak applicability, which is reflected in the lack of high brightness usually accomplished by a good electrical contact [87,88] and a high current [45]. One of the main reasons was the dependence of the emission current on the CNT density in the matrix [46].…”

Section: Cnt Suspension For Fe Cathodesmentioning

confidence: 88%

Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions

Laszczyk

2020

Micromachines

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In the first decade of our century, carbon nanotubes (CNTs) became a wonderful emitting material for field-emission (FE) of electrons. The carbon nanotube field-emission (CNT-FE) cathodes showed the possibility of low threshold voltage, therefore low power operation, together with a long lifetime, high brightness, and coherent beams of electrons. Thanks to this, CNT-FE cathodes have come ahead of increasing demand for novel self-sustaining and miniaturized devices performing as X-ray tubes, X-ray spectrometers, and electron microscopes, which possess low weight and might work without the need of the specialized equipped room, e.g., in a harsh environment and inaccessible-so-far areas. In this review, the author discusses the current state of CNT-FE cathode research using CNT suspensions. Included in this review are the basics of cathode operation, an evaluation, and fabrication techniques. The cathodes are compared based on performance and correlated issues. The author includes the advancement in field-emission enhancement by postprocess treatments, incorporation of fillers, and the use of film coatings with lower work functions than that of CNTs. Each approach is discussed in the context of the CNT-FE cathode operating factors. Finally, we discuss the issues and perspectives of the CNT-FE cathode research and development.

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Section: Cnt Suspension For Fe Cathodesmentioning

confidence: 88%

Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions

Laszczyk

2020

Micromachines

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“…Nanoscale electrical contacts have attracted substantial attention due to the advancements in nanotechnology, material sciences and growing demands for miniaturization of electronic devices and high packing density. Contact resistance and their electro-thermal effects have become one of the most critical concerns of very large scale integration (VLSI) circuit designers, because of the excessive amount of Joule heating being deposited at the contact region [1][2][3][4][5][6] . The electrical contact properties have been extensively studied in metal-semiconductor [7][8][9] , metal-insulatorsemiconductor and metal-insulator-metal [10][11][12][13] junctions.…”

Section: Introductionmentioning

confidence: 99%

A Two Dimensional Tunneling Resistance Transmission Line Model for Nanoscale Parallel Electrical Contacts

Banerjee

Luginsland

Zhang

2019

Sci Rep

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Contact resistance and current crowding are important to nanoscale electrical contacts. In this paper, we present a self-consistent model to characterize partially overlapped parallel contacts with varying specific contact resistivity along the contact length. For parallel tunneling contacts formed between contacting members separated by a thin insulating gap, we examine the local voltage-dependent variation of potential barrier height and tunneling current along the contact length, by solving the lumped circuit transmission line model (TLM) equations coupled with the tunneling current self consistently. The current and voltage distribution along the parallel tunneling contacts and their overall contact resistance are analyzed in detail, for various input voltage, electrical contact dimension, and material properties (i.e. work function, sheet resistance of the contact members, and permittivity of the insulating layer). It is found the existing one-dimensional (1D) tunneling junction models become less reliable when the tunneling layer thickness becomes smaller or the applied voltage becomes larger. In these regimes, the proposed self-consistent model may provide a more accurate evaluation of the parallel tunneling contacts. For the special case of constant ohmic specific contact resistivity along the contact length, our theory has been spot-checked with finite element method (FEM) based numerical simulations. This work provides insights on the design, and potential engineering, of nanoscale electrical contacts with controlled current distribution and contact resistance via engineered spatially varying contact layer properties and geometry.

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“…Carbon nanotube (CNT) fibers [1][2][3][4][5][6][7][8][9][10][11][12] have demonstrated significant promise as field emission (FE) cathodes due to their large aspect ratios and high electrical and thermal conductivities. They can potentially be used as FE cathodes in a wide range of applications, including compact radiation sources [13][14][15][16], electron guns for ring and linear accelerators [17], and vacuum nanoelectronics [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…CNT fiber emitters are typically mounted vertically on a substrate [3,5,6] in order to take advantage of the high field enhancement factor due to their high aspect ratio. The tips of the fibers are cut either mechanically or by a laser [23].…”

Section: Introductionmentioning

confidence: 99%

“…There are ongoing efforts to better understand the heating and temperature distribution of CNT fiber field emitters, including direct Infrared (IR) imaging [23], a multiscale model of heat dissipation [26], coupled electrical-thermal conduction with the effects of temperature dependent electrical and thermal conductivities [27], morphology dependent field emission [3], and the effects of contact resistance [6,28]. In this paper, we study field emission from a looped CNT fiber emitter and compare the temperature distribution with a single vertical CNT fiber emitter ( Figure 2).…”

Section: Introductionmentioning

confidence: 99%

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Temperature Comparison of Looped and Vertical Carbon Nanotube Fibers during Field Emission

et al. 2018

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Carbon nanotube (CNT) fiber-based emitters have shown great potential to deliver stable, high current beams for various potential applications. Because of joule heating, CNT field emitters are heated to high temperatures during field emission. It is important to improve the thermal management of emitters to increase their reliability and prevent premature failure. This paper compares the field emission characteristics and the temperature distribution of a new configuration of a looped CNT fiber emitter with a traditional single vertical CNT fiber emitter. It is found that the maximum temperature of the looped fiber emitter (~300 °C) is significantly reduced compared to that of the vertical fiber (~600 °C) at the same emission current of 3 mA. The experimentally measured temperature distribution is compared with a recent theory on joule heating of a one-dimensional conductor. This study provides new insights into the design of high performance field emitters.

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Field emission from carbon nanotube fibers in varying anode-cathode gap with the consideration of contact resistance

Cited by 41 publications

References 38 publications

Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions

Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions

A Two Dimensional Tunneling Resistance Transmission Line Model for Nanoscale Parallel Electrical Contacts

Temperature Comparison of Looped and Vertical Carbon Nanotube Fibers during Field Emission

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