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

Zhang, Peng; Park, Jeong-Ho; Fairchild, Steven B.; Lockwood, Nathaniel P.; Lau, Y. Y.; Ferguson, J. B.; Back, Tyson C.

doi:10.3390/app8071175

Cited by 34 publications

(5 citation statements)

References 42 publications

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“…Once such a tool becomes available, it would find immense applications in various areas, such as solid state physics, strong fields, ultrafast sciences, vacuum electronics, and accelerators and beams. [36] 16 [45] 10.7 [46] 14 [47] CNT fiber 13.1 [48][49][50] as a function of the phase difference between the two-color lasers , for different / , with fixed 1.6 V/nm. Blue and red lines denote the experimentally observed emission electron current and the sine fit from Fig.…”

Section: Discussionmentioning

confidence: 99%

Analysis of two-color laser-induced electron emission from a biased metal surface using an exact quantum mechanical solution

Luo

Zhang

2019

Phys. Rev. Applied

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Photoelectron emission from solids driven by high intensity lasers offers a platform for the coherent control of electron motion in ultrashort spatiotemporal scales. By solving the time-dependent Schrödinger equation, we present an exact analytical solution for the nonlinear ultrafast electron emission from a dc biased metal surface illuminated by two-color laser fields. We systematically examine the combined effects of a dc electric field and the two-color laser fields. In addition to the remarkable tunability of electron emission processes due to the interference of the two-color laser fields, we find that a strong dc electric field not only opens up more tunneling emission channels, but also introduces intense modulation to the emission current. We found the surprising results that strong current modulation (with respect to the phase difference of the two-color lasers) persists (>70%) even with a large dc bias (i.e. ratio of the electric fields for dc : fundamental laser : second harmonic laser 1 : 0.5 : 0.07). In the meantime, the average emission current level increases by about three orders of magnitude compared to the case of zero dc bias. Application of our model to time-resolved photoelectron spectroscopy is exemplified, showing the dynamics of the n-photon excited states depends strongly on the applied dc field. Our study suggests a practical way to maintain a strong modulation to high current photoemission, by the addition of a large dc bias for two-color laser induced electron emission.

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Section: Discussionmentioning

confidence: 99%

Analysis of two-color laser-induced electron emission from a biased metal surface using an exact quantum mechanical solution

Luo

Zhang

2019

Phys. Rev. Applied

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“…The fibers were fabricated using a wet spinning technique described by Behabtu et al[8]. This fabrication process ensures that the CNTs comprising the fibers are closely packed and highly aligned which ensures high electrical and thermal conductivity [9] as well as optimal performance when used as eiher wire conductors or field emission cathodes [8,[10][11][12]. Carbon nanotube yarns are made by twisting or braiding together multiple CNT fibers.…”

Section: Samples and Experimentalmentioning

confidence: 99%

Field emission microscopy of carbon nanotube fibers: Evaluating and interpreting spatial emission

Posos

Fairchild

Park

et al. 2020

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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In this work, we quantify field emission properties of cathodes made from carbon nanotube (CNT) fibers. The cathodes were arranged in different configurations to determine the effect of cathode geometry on the emission properties. Various geometries were investigated including: 1) flat cut fiber tip, 2) folded fiber, 3) looped fiber and 4) and fibers wound around a cylinder. We employ a custom field emission microscope to quantify I-V characteristics in combination with laterallyresolved field-dependent electron emission area. Additionally we look at the very early emission stages, first when a CNT fiber is turned on for the first time which is then followed by multiple ramp-up/down. Upon the first turn on, all fibers demonstrated limited and discrete emission area. During ramping runs, all CNT fibers underwent multiple (minor and/or major) breakdowns which improved emission properties in that turn-on field decreased, field enhancement factor and emission area both increased. It is proposed that breakdowns are responsible for removing initially undesirable emission sites caused by stray fibers higher than average. This initial breakdown process gives way to a larger emission area that is created when the CNT fiber sub components unfold and align with the electric field. Our results form the basis for careful evaluation of CNT fiber cathodes for dc or low frequency pulsed power systems in which large uniform area emission is required, or for narrow beam high frequency applications in which high brightness is a must.

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“…Equations (5) and (6) are solved to give the voltage and current distribution along and across the contact interface as well as the total contact resistance, for a given electrical contact ( Fig. 1) with spatially dependent interface specific contact resistivity ̅ ( ̅ ).…”

Section: Formulationmentioning

confidence: 99%

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

Cited by 34 publications

References 42 publications

Analysis of two-color laser-induced electron emission from a biased metal surface using an exact quantum mechanical solution

Analysis of two-color laser-induced electron emission from a biased metal surface using an exact quantum mechanical solution

Field emission microscopy of carbon nanotube fibers: Evaluating and interpreting spatial emission

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

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