562 results about "Field emission device" patented technology

The present invention is directed to nanowire structures and interconnected nanowire networks comprising such structures, as well as methods for their production. The nanowire structures comprise a nanowire core, a carbon-based layer, and in additional embodiments, carbon-based structures such as nanographitic plates consisting of graphenes formed on the nanowire cores, interconnecting the nanowire structures in the networks. The networks are porous structures that can be formed into membranes or particles. The nanowire structures and the networks formed using them are useful in catalyst and electrode applications, including fuel cells, as well as field emission devices, support substrates and chromatographic applications.

The present invention is directed to nanowire structures and interconnected nanowire networks comprising such structures, as well as methods for their production. The nanowire structures comprise a nanowire core, a carbon-based layer, and in additional embodiments, carbon-based structures such as nanographitic plates consisting of graphenes formed on the nanowire cores, interconnecting the nanowire structures in the networks. The networks are porous structures that can be formed into membranes or particles. The nanowire structures and the networks formed using them are useful in catalyst and electrode applications, including fuel cells, as well as field emission devices, support substrates and chromatographic applications.

The present invention relates to a field emission device comprising an anode and a cathode, wherein said cathode includes carbon nanotubes which have been treated with an ion beam. The ion beam may be any ions, including gallium, hydrogen, helium, argon, carbon, oxygen, and xenon ions. The present invention also relates to a field emission cathode comprising carbon nanotubes, wherein the nanotubes have been treated with an ion beam. 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 treated with an ion beam is further disclosed.

The present invention is directed toward cathodes and cathode materials comprising carbon nanotubes (CNTs) and particles. The present invention is also directed toward field emission devices comprising a cathode of the present invention, as well as methods for making these cathodes. In some embodiments, the cathode of the present invention is used in a field emission display. The invention also comprises a method of depositing a layer of CNTs and particles onto a substrate to form a cathode of the present invention, as well as a method of controlling the density of CNTs used in this mixed layer in an effort to optimize the field emission properties of the resulting layer for field emission display applications.

Methods of growing carbon nanotubes and manufacturing a field emission device using the carbon nanotubes are provided. The method of growing carbon nanotubes includes the steps of preparing a substrate, forming a catalyst metal layer on the substrate to promote the growing of the carbon nanotubes, forming an amorphous carbon layer on the catalyst metal layer where the amorphous carbon layer partially covers the catalyst metal layer, and growing the carbon nanotubes from a surface of the catalyst metal layer. The carbon nanotubes are grown in a portion of the surface of the catalyst metal layer that is not covered by the amorphous carbon layer. In the method of growing carbon nanotubes, the carbon nanotubes are grow at a low temperature. A density of carbon nanotubes can be controlled to improve field emission characteristics of an emitter of a field emission device.

A preferred method for making a carbon nanotube-based field emission device in accordance with the invention includes the following steps: providing a substrate (22) with a surface; depositing a catalyst layer (24) on a predetermined area on the surface of the substrate; forming a carbon nanotube array (30) extending from the predetermined area; forming a cathode electrode (40) on top of the carbon nanotube array; and removing the substrate so as to expose the carbon nanotube array.

Gated field emission devices and systems and methods for their fabrication are described. A method includes growing a substantially vertically aligned carbon nanostructure, the substantially vertically aligned carbon nanostructure coupled to a substrate; covering at least a portion of the substantially vertically aligned carbon nanostructure with a dielectric; forming a gate, the gate coupled to the dielectric; and releasing the substantially vertically aligned carbon nanostructure by forming an aperture in the gate and removing a portion of the dielectric.

A carbon nanotube field emission device (100) includes a substrate (10), and a carbon nanotube array (30) formed on and secured to the substrate. This avoids separation of the carbon nanotubes from the substrate by electric field force in a strong electric field. Tips of the carbon nanotubes are exposed. A method for manufacturing the carbon nanotube field emission device includes the steps of: (a) depositing a catalyst film (20) on a substrate; (b) forming a carbon nanotube array on the substrate; (c) injecting an adhesive into the carbon nanotube array, and drying the adhesive; and (d) treating surfaces of the carbon nanotube array by laser. The carbon nanotube field emission device has reduced shielding between adjacent carbon nanotubes, reduced threshold voltage, and increased field emission current.

Composites of single-walled carbon nanotubes (SWNTs) and a ceramic support (e.g., silica) comprising a small amount of catalytic metal, e.g., cobalt and molybdenum, are described. The particle comprising the metal and ceramic support is used as the catalyst for the production of the single-walled carbon nanotubes. The nanotube-ceramic composite thus produced can be used “as prepared” without further purification providing significant cost advantages. The nanotube-ceramic composite has also been shown to have improved properties versus those of purified carbon nanotubes in certain applications such as field emission devices. Use of precipitated and fumed silicas has resulted in nanotube-ceramic composites which may synergistically improve the properties of both the ceramic (e.g., silica) and the single-walled carbon nanotubes. Addition of these composites to polymers may improve their properties. These properties include thermal conductivity, thermal stability (tolerance to degradation), electrical conductivity, modification of crystallization kinetics, strength, elasticity modulus, fracture toughness, and other mechanical properties. Other nanotube-ceramic composites may be produced based on Al2O3, MgO and ZrO2, for example, which are suitable for a large variety of applications.

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.