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Field emission devices using modified carbon nanotubes

a carbon nanotube and field emission technology, applied in the manufacture of electrode systems, electric discharge tubes/lamps, tubes with screens, etc., can solve the problem of non-uniform current density between pixels, and achieve the effect of reducing working voltage, increasing emissions, and increasing emission sites

Inactive Publication Date: 2005-12-15
HYPERION CATALYSIS INT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

"The present invention relates to a field emission cathode comprising carbon nanotubes that have been treated using various methods such as energy, chemical, plasma, or mechanical treatment. The carbon nanotubes may be deposited onto a substrate or formed into a cathode by dispersing them in a liquid and transferring them onto a substrate. The invention also includes field emission devices comprising a cathode with carbon nanotubes and a dielectric film, as well as a power supply. The carbon nanotubes used in the invention are single wall or multi-wall, with a uniform diameter and length to diameter ratio greater than 5. The invention also includes methods for treating the carbon nanotubes using various techniques such as ion beams, plasma, chemical treatment, and laser beams. The technical effects of the invention include improved field emission performance and stability of the carbon nanotube cathode."

Problems solved by technology

The problem with metal emitter tips is that the control voltage required for emission is relatively high, e.g., around 100 V. Moreover, these emitter tips lack uniformity resulting in non-uniform current density between pixels.

Method used

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  • Field emission devices using modified carbon nanotubes
  • Field emission devices using modified carbon nanotubes
  • Field emission devices using modified carbon nanotubes

Examples

Experimental program
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Effect test

example i

Preparation of Nanotube Film on Aluminum Substrate

[0068] With reference to FIG. 5, a solution is formed that contains 150 ml i-propyl alcohol (IPA) and 0.44 grams of acid washed carbon nanotubes. This solution is placed in an electrophoresis bath 5000.

[0069] A patterned, aluminum coated glass substrate 5002 serves as one electrode in electrophoresis bath 5000. The pattern forms the pixel size. The smallest feature size can be ca. 1 micron. The aluminum coated glass 5002 is about 55 mm×45 mm×1 mm in its dimensions. The aluminum pattern size is about 9 mm×9 mm. The other electrode, tantalum (Ta) electrode 5004 is also inserted into the electrophoresis bath 5000. A spacer 5006 separates the aluminum coated glass 5002 from the tantalum electrode 5004. A DC voltage, for example between 40 to 120 volts, e.g., 100 volts is applied to the electrodes. A current between 1.0 to 5 mA, e.g., 3.8 mA, is observed between the electrodes. The duration of the preparation time can be between about 3...

example ii

Emission Characteristics of Ion-Beam-Treated Nanotube Films

[0114] Carbon nanotube films fabricated by electrophoresis on an aluminum layer deposited on a glass have been locally irradiated with focused ion beans. A diode structure with a distance of 125 μm between cathodes and anodes was used for emission measurement. A maximum emission current of 375 microamps with a turn-on voltage of 2.8 V / μm for carbon nanotube emitters was found to decrease by focused ion beam irradiation to 1.1 V / μm with increase in emission current by a factor of six.

[0115] The current range that was used in the test was in the low range with an anode voltage of about 400 to 500 volts, close to the turn-on (threshold) voltage for field emission. The change was from 0.05 to about 0.18 microamps to more than 0.9 microamps with a drastic change in the F-N plot of FIG. 9.

[0116] The physical and chemical effects of ion bombardment on carbon nanotubes are not entirely known. While not wishing to be bound to any ...

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Abstract

The present invention relates to a field emission device comprising an anode and a cathode, wherein said cathode includes carbon nanotubes nanotubes which have been subjected to energy, plasma, chemical, or mechanical treatment. The present invention also relates to a field emission cathode comprising carbon nanotubes which have been subject to such treatment. A method for treating the carbon nanotubes and for creating a field emission cathode is also disclosed. A field emission display device containing carbon nanotube which have been subject to such treatment is further disclosed.

Description

[0001] This application claims the benefit of U.S. Provisional Application No. 60 / 298,193, filed Jun. 14, 2001, hereby incorporated by reference.FIELD OF INVENTION [0002] The present invention relates to field emission cathodes which use carbon nanotubes. BACKGROUND OF THE INVENTION [0003] Field emission devices are devices that capitalize on the movement of electrons. A typical field emission device includes at least a cathode, emitter tips, and an anode spaced from the cathode. A voltage is applied between the cathode and the anode causing electrons to be emitted from the emitter tips. The electrons travel in the direction from the cathode to the anode. [0004] These devices can be used in a variety of applications including, but not limited to, microwave vacuum tube devices, power amplifiers, ion guns, high energy accelerators, free electron lasers, and electron microscopes, and in particular, flat panel displays. Flat panel displays can be used as replacements for conventional ca...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B82B3/00C01B31/02H01J1/304H01J9/02H01J29/04H01J31/12
CPCB82Y10/00H01J1/304H01J9/025H01J29/04H01J29/481H01J2201/30469H01J2329/00C01B32/05B82Y40/00
Inventor TAKAI, MIKIOFISCHER, ALAN B.NIU, CHUNMINGTENNENT, HOWARD G.HOCH, ROBERTBIEBUYCK, HANS
Owner HYPERION CATALYSIS INT
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