Abstract: A carbon nanotube-based device (40) includes a substrate (10), a number of alloyed, nano-sized catalytic particles (26) formed on the substrate, and an array of aligned carbon nanotubes (15) extending from the alloyed, nano-sized catalytic particles. The nanotube array bends in an arcuate configuation. A method for making the carbon nanotube-based device includes the steps of: providing a substrate; depositing a catalyst layer on the substrate; depositing two different layers of catalyst-doped materials on different areas of the catalyst layer for accelerating or decelerating the rate of synthesis of the aligned carbon nanotube array; annealing the catalyst and the catalyst-doped materials in an oxygen-containing gas at a low temperature; introducing a carbon source gas; and forming an array of aligned carbon nanotubes extending from the alloyed, nano-sized catalytic particles using a chemical vapor deposition method.

Abstract: The present invention provides a method for manufacturing carbon nanotubes. The method includes the following steps: (a) providing a substrate (3); (b) depositing a catalyst material (1) onto the substrate; (c) exposing the catalyst material to a carbon containing gas for a predetermined period of time in a predetermined temperature such that an array of carbon nanotube having a predetermined length grows from the substrate in a direction substantially perpendicular to the substrate; (d) removing the carbon nanotubes from the substrate; and (e) dispersing the carbon nanotubes via ultrasonication in a dispersant, the dispersant being ethanol or 1-2 dichloroethane. The carbon nanotubes of the present invention have a predetermined same length and are aligned parallel to each other.

Abstract: A field emission device includes a substrate (11) and a carbon nanotube array (12) formed thereon. Carbon nanotubes (120) of the carbon nanotube array are parallel to each other and cooperatively form a plurality of substantially rod-shaped lower portions (121, 121′) and a plurality of corresponding tapered tips (122, 122′) above the lower portions. Each lower portion and tapered tips have a plurality of carbon nanotubes. Distances between adjacent tips are approximately uniform, and are more than one micrometer. Preferably, the distance is in the range from 1 to 30 micrometers. The field emission device with this structure has reduced shielding between adjacent carbon nanotubes and has decreased threshold voltage required for field emission by the carbon nanotubes. The field emission device also contributes to an improved field emission concentration and efficiency.

Abstract: A thermal interface material (40) includes a polymer matrix (32) and an array of carbon nanotubes (22) incorporated in the polymer matrix. The polymer matrix has a thermally conductive first face (42) and an opposite thermally conductive second face (44). The carbon nanotubes are substantially parallel to each other, and extend between the first and the second faces. A preferred method for making the thermal interface material includes the steps of: (a) forming the array of carbon nanotubes on a substrate (11); (b) immersing the carbon nanotubes in a liquid prepolymer (31) such that the liquid prepolymer infuses into the array of carbon nanotubes; (c) polymerizing the liquid prepolymer to obtain the polymer matrix having the carbon nanotubes secured therein; and (d) peeling the polymer matrix having the carbon nanotubes off from the substrate to obtain the thermal interface material.

Abstract: A method for forming a carbon nanotube array includes the following steps: providing a smooth substrate (11); depositing a metal catalyst layer (21) on a surface of the substrate; heating the treated substrate to a predetermined temperature in flowing protective gas; and introducing a mixture of carbon source gas and protective gas for 5-30 minutes, thus forming a carbon nanotube array (61) extending from the substrate. When the mixture of carbon source gas and protective gas is introduced, a temperature differential greater than 50° C. between the catalyst and its surrounding environment is created by adjusting a flow rate of the carbon source gas. Further, a partial pressure of the carbon source gas is maintained lower than 20%, by adjusting a ratio of the flow rates of the carbon source gas and the protective gas. The carbon nanotubes formed in the carbon nanotube array are well bundled.

Abstract: A method of fabricating a long carbon nanotube yarn includes the following steps: (1) providing a flat and smooth substrate; (2) depositing a catalyst on the substrate; (3) positioning the substrate with the catalyst in a furnace; (4) heating the furnace to a predetermined temperature; (5) supplying a mixture of carbon containing gas and protecting gas into the furnace; (6) controlling a difference between the local temperature of the catalyst and the furnace temperature to be at least 50° C.; (7) controlling the partial pressure of the carbon containing gas to be less than 0.2; (8) growing a number of carbon nanotubes on the substrate such that a carbon nanotube array is formed on the substrate; and (9) drawing out a bundle of carbon nanotubes from the carbon nanotube array such that a carbon nanotube yarn is formed.

Abstract: A light filament (206) formed from carbon nanotubes is characterized by high mechanical strength and durability at elevated temperatures, a high surface area to volume ratio, and high emissivity. Additionally, electrical resistance of the light filament does not increase with increasing temperature as much as electrical resistance of metallic light filaments. Accordingly, power consumption of the light filament is low at incandescent operating temperatures. A method for making a light filament made of carbon nanotubes includes the steps of: forming an array of carbon nanotubes (20); pulling out carbon nanotube yarn (204) from the carbon nanotube array; and winding the yarn between two leads (30) functioning as electrodes to form the light filament.

Abstract: A method for processing one-dimensional nano-materials includes the following steps: providing a substrate (11); forming one-dimensional nano-materials (12) on the substrate, the one-dimensional nano-materials being substantially parallel to each other and each being substantially perpendicular to the substrate, the one-dimensional nano-materials cooperatively defining a top surface distal from the substrate; and applying physical energy (14) by means of a high-energy pulse laser beam to the top surface of the one-dimensional nano-materials. The resulting one-dimensional nano-materials have sharp, tapered tips (15, 15′). Distances between adjacent tips are approximately uniform, and are relatively large. This reduces shielding between adjacent one-dimensional nano-materials. The tips also contribute to a decreased threshold voltage required for field emission by the one-dimensional nano-materials.

Abstract: A field emission device having bundles of aligned parallel carbon nanotubes on a substrate. The carbon nanotubes are oriented perpendicular to the substrate. The carbon nanotube bundles may be up to 300 microns tall, for example. The bundles of carbon nanotubes extend only from regions of the substrate patterned with a catalyst material. Preferably, the catalyst material is iron oxide. The substrate is preferably porous silicon, as this produces the highest quality, most well-aligned nanotubes. Smooth, nonporous silicon or quartz can also be used as the substrate. The method of the invention starts with forming a porous layer on a silicon substrate by electrochemical etching. Then, a thin layer of iron is deposited on the porous layer in patterned regions. The iron is then oxidized into iron oxide, and then the substrate is exposed to ethylene gas at elevated temperature. The iron oxide catalyzes the formation of bundles of aligned parallel carbon nanotubes which grow perpendicular to the substrate surface.

Abstract: A field emission device having bundles of aligned parallel carbon nanotubes on a substrate. The carbon nanotubes are oriented perpendicular to the substrate. The carbon nanotube bundles may be up to 300 microns tall, for example. The bundles of carbon nanotubes extend only from regions of the substrate patterned with a catalyst material. Preferably, the catalyst material is iron oxide. The substrate is preferably porous silicon, as this produces the highest quality, most well-aligned nanotubes. Smooth, nonporous silicon or quartz can also be used as the substrate. The method of the invention starts with forming a porous layer on a silicon substrate by electrochemical etching. Then, a thin layer of iron is deposited on the porous layer in patterned regions. The iron is then oxidized into iron oxide, and then the substrate is exposed to ethylene gas at elevated temperature. The iron oxide catalyzes the formation of bundles of aligned parallel carbon nanotubes which grow perpendicular to the substrate surface.