Degradation and Failure of Field Emitting Carbon Nanotube Arrays

Mahapatra, D. Roy; Sinha, Niraj; Melnik, Roderick

doi:10.1166/jnn.2011.3829

Cited by 5 publications

(6 citation statements)

References 11 publications

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“…The increase in the voltage required to maintain 5 μA emission over time suggests gradual CNT field emitter degradation (Figure 2c). This degradation effect has been reported previously [28][29][30][31][32] and was related to several distinct causes, including shortening of the CNTs from ion bombardment and damage to the sidewalls from joule heating at the CNT tip during electron field emission. The voltage spikes observed in Figure 2c can be attributed to sudden changes in emission current forcing fast instrument correction to maintain the set current.…”

Section: Ex-situ Characterizationsupporting

confidence: 75%

“…These sudden changes in emission current could be explained by CNTs undergoing deflection during the emitting process. It has been reported [32] that transients in emission current can be caused by electrodynamic interactions between field emitting CNTs. Deflected CNTs experiencing these interactions can undergo an abrupt pull, resulting in the sudden current changes.…”

Section: Ex-situ Characterizationmentioning

confidence: 99%

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Chemical Ionization Mass Spectrometry Using Carbon Nanotube Field Emission Electron Sources

Radauscher

Keil

Wells

et al. 2015

J. Am. Soc. Mass Spectrom.

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Abstract. A novel chemical ionization (CI) source has been developed based on a carbon nanotube (CNT) field emission electron source. The CNT-based electron source was evaluated and compared with a standard filament thermionic electron source in a commercial explosives trace detection desktop mass spectrometer. This work demonstrates the first reported use of a CNT-based ion source capable of collecting CI mass spectra. Both positive and negative modes were investigated. Spectra were collected for a standard mass spectrometer calibration compound, perfluorotributylamine (PFTBA), as well as trace explosives including trinitrotoluene (TNT), Research Department explosive (RDX), and pentaerythritol tetranitrate (PETN). The electrical characteristics, lifetime at operating pressure, and power requirements of the CNT-based electron source are reported. The CNT field emission electron sources demonstrated an average lifetime of 320 h when operated in constant emission mode under elevated CI pressures. The ability of the CNT field emission source to cycle on and off can provide enhanced lifetime and reduced power consumption without sacrificing performance and detection capabilities.

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Section: Ex-situ Characterizationsupporting

confidence: 75%

Section: Ex-situ Characterizationmentioning

confidence: 99%

Chemical Ionization Mass Spectrometry Using Carbon Nanotube Field Emission Electron Sources

Radauscher

Keil

Wells

et al. 2015

J. Am. Soc. Mass Spectrom.

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“…However, mechanisms of device failure must also be studied to improve device performance and lifetime. There have been numerous studies [69][70][71] on the failure mechanisms of standalone CNT field emitters that have identified several possible causes of failure.…”

Section: Improving Cnt Adhesion To Polysiliconmentioning

confidence: 99%

“…Examples include fracturing of the CNT tips during operation due to oxidative ablation of the CNTs caused by local resistive heating (i.e. thermo-mechanically activated fracture) [70,72], degradation due to ion irradiation/bombardment [73,74], and extraction of the CNT from the substrate due to either electrodynamic forces or increased resistive heating at the substrate-CNT interface [70,71]. In the case of CNT emitters grown on MEMS polysilicon-based substrates, poor adhesion between the CNT emitter and its substrate is the primary limiting factor for overall device lifetime.…”

Section: Improving Cnt Adhesion To Polysiliconmentioning

confidence: 99%

Integrating carbon nanotube forests into polysilicon MEMS: Growth kinetics, mechanisms, and adhesion

Ubnoske

Radauscher

Meshot

et al. 2017

Carbon

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The growth of carbon nanotubes (CNTs) on polycrystalline silicon substrates was studied to improve the design of CNT field emission sources for microelectromechanical systems (MEMS) applications and vacuum microelectronic devices (VMDs). Microwave plasmaenhanced chemical vapor deposition (PECVD) was used for CNT growth, resulting in CNTs that incorporate the catalyst particle at their base. The kinetics of CNT growth on polysilicon were compared to growth on Si (100) using the model of Deal and Grove, finding activation energies of 1.61 and 1.54 eV for the nucleation phase of growth and 1.90 and 3.69 eV for the diffusion-limited phase on Si (100) and polysilicon, respectively. Diffusivity values for growth on polysilicon were notably lower than the corresponding values on Si (100) and the growth process became diffusion-limited earlier. Evidence favors a surface diffusion growth mechanism involving diffusion of carbon precursor species along the length of the CNT forest to the catalyst at the base. Explanations for the differences in activation energies and diffusivities were elucidated by SEM analysis of the catalyst nanoparticle arrays and through wide-angle X-ray scattering (WAXS) of CNT forests. Finally, methods are presented to improve adhesion of CNT films during operation as field emitters, resulting in a 2.5x improvement.

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“…2 We assume that the nanotubes are placed into a homogeneous dielectric medium, nanotube axes are parallel to a common axis Ox, and the distance between neighboring nanotubes is large compared to 1350045-2 their diameter. While applications exist where this may not be the case, [17][18][19][20][21] the latter assumption allows us to neglect the interaction between nanotubes. Given the geometry, the dispersion law of conduction electrons in the nanotube has the form…”

Section: Basic Relations and The Wave Equationmentioning

confidence: 99%

Propagation of Laser Beams in an Array of Semiconductor Carbon Nanotubes

et al. 2013

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In this paper, we consider propagation of a monochromatic laser beam in an array of semiconductor carbon nanotubes. Initial distribution of the beam intensity is taken in the form of a Gaussian profile in the plane perpendicular to the wave vector. The electromagnetic field in an array of nanotubes is described by Maxwell equations, reduced to a multidimensional wave equation. With an approximation of the slowly varying amplitudes and phases, we derive the effective equation describing the time-averaged field intensity distribution of the laser beam in a medium. Numerical solution of the derived equations allows us to analyze the dependence of the diffractive spreading of the beam on its frequency and initial amplitude. Furthermore, the influence of the nanotube radius on the diffractive spreading of the laser beam is investigated.

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Degradation and Failure of Field Emitting Carbon Nanotube Arrays

Cited by 5 publications

References 11 publications

Chemical Ionization Mass Spectrometry Using Carbon Nanotube Field Emission Electron Sources

Chemical Ionization Mass Spectrometry Using Carbon Nanotube Field Emission Electron Sources

Integrating carbon nanotube forests into polysilicon MEMS: Growth kinetics, mechanisms, and adhesion

Propagation of Laser Beams in an Array of Semiconductor Carbon Nanotubes

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