Software Technology for “White light source using carbon Nanotubes and the fabrication method thereof”

Nanotechnology – Cheol-jin Lee, Jae-eun Yoo, Iljin Nanotech Co Ltd

Abstract for “White light source using carbon Nanotubes and the fabrication method thereof”

“A white light source made from carbon nanotubes is provided and the fabrication process thereof. The white light source consists of a metal substrate that is used as a cathode and a catalytic film on the metal substrate, carbon nanotubes vertically aligned on catalytic film for emission electrons in an applied electrical field, spacers on the catalytic film and a transparent substrate with a transparent electrode and a fluorescent body. This substrate is mounted on spacers so that the fluorescent body faces carbon nanotubes. Catalytic metal films are composed of nano-sized catalytical metal particles. Each of the catalytic metallic particles is grown to create carbon nanotubes that are vertically aligned onto the substrate using chemical vapor deposition.

Background for “White light source using carbon Nanotubes and the fabrication method thereof”

“1. “1.

“The invention is a white light source and, more specifically, a method for manufacturing a white source with an excellent luminous efficacy.”

“2. “2.

A fluorescent lamp is an example of a representative white light source. Fluorescent lamps emit light from a fluorescent body through a discharge effect. Low luminance is a drawback to this fluorescent lamp. It is also difficult to reduce the size of the fluorescent lamp. The fluorescent lamp’s luminance decreases with time. The fluorescent lamp’s reliability and stability are affected, and its life span is also reduced.

“To address the above problems, the present invention provides a white light source with an excellent electron emission efficiency in an electric field to obtain a large emission current even when applied voltage is low. It also has a high density electron emitters per area to exhibit excellent luminance. The fabrication method of this light source is also provided.”

The present invention includes a white light source that includes a metal substrate as a cathode. A catalytic metallic film is formed on the lower substrate. Carbon nanotubes are attached to the transparent substrate. To the transparent electrode, a fluorescent body is attached. The transparent substrate is mounted on the spacers so that the fluorescent body faces carbon nanotubes.

The catalytic metallic film can be made of nano-sized catalytical metal particles. Carbon nanotubes can be vertically grown by chemical vapor deposition from each catalytical metal particle. Here, the catalytic metal film may be formed of cobalt, nickel, iron, yttrium or an alloy of at least two of them, and the fluorescent body may be formed of (3Ca3(PO4)2CaFCl/Sb,Mn), generating a white luminescence, or a combination of Y2O3:Eu, CeMaA11O19:Tb and BaMg2Al16O7:Eu, to generate a white luminescence by combining different emission spectrums.”

“The white light source could also include an insulation film pattern with openings that selectively expose the catalytic metallic film. The carbon nanotubes can be placed on portions of the catalytic metallic film that are exposed through these openings. The insulation film may have spacers.

“The invention also provides a method for fabricating a white-light source. On a lower substrate, a metal film is formed that can be used as a cathode. The metal film forms a catalytical metal film. The catalytic metallic film is used to grow carbon nanotubes that emit electrons in an applied electrical field. The catalytical metal film is fitted with a spacer. The spacer is a transparent upper substrate with a transparent electrode that has a fluorescent body. The transparent upper substrate is sealed to the lower substrate.

An insulating material can also be used to form a reaction-preventing film. This prevents the reaction between the lower substrate, the metal film and the next step of making the metal film. The catalytical metal film is created by depositing the catalytical metal film and then etching the deposited catalyst metal film to separate the catalytical metal film into tiny catalytical metal particles. Each catalytic metal particle is used to grow carbon nanotubes that are vertically aligned onto the substrate using chemical vapor deposition.

“Catalytic metal films may contain cobalt, nickel or iron as well as yttrium, or an alloy of at most two of these elements. The catalytical metal film can also be coated with an insulation film pattern that has openings that selectively expose the catalytical metal film. The carbon nanotubes can be located in the exposed portions of the catalytical metal film through these openings. Spacers can also be mounted on this insulation film pattern.

“The invention is capable of providing a white light source that can be very small and portable and has high efficiency and power saving.”

“The following describes the embodiments of the invention in detail, with reference to the attached illustrations. The present invention does not limit itself to the following embodiments. Many variations are possible within its scope and spirit. To better explain the invention to those skilled in the art, the embodiments of the invention have been provided. The drawings show members in exaggerated shapes. The same reference numbers denote the same members. A film described as being on another layer or a semiconductor substrate can also be on the same film.

The present invention provides a white-light source made from carbon nanotubes, and a method for fabricating them. A carbon nanotube can be microscopically made so that one carbon element is combined and three neighboring carbon elements. This creates a hexagonal-shaped ring by the combination of the carbon molecules. The hexagonal ring is then formed by rolling a plan composed of repeated hexagonal rings, like a honeycomb, to form a cylindrical shape. The cylindrical structure has a diameter of several nanometers to several tens or more nanometers and a length that is several tens to several thousands of feet longer than its diameter.

According to this, the tip of a carbon-nanotube’s tip has a diameter of several micrometers. It can also be a few tens of nanometers in length. This allows for high electron emission efficiency when applied electric fields are applied. A low voltage can produce a high amount of emission current. Carbon nanotubes can also be grown at a high density per unit area, which allows for excellent luminescence.

“The present invention will be described in greater detail with the help of the accompanying drawings. These drawings show preferred embodiments.”

“FIG. “FIG. Referring to FIG. Referring to FIG. 1, the white light source according the first embodiment is a 200-gauge metal film that acts as a cathode on a 100-gauge lower substrate and 300-gauge catalytic metal films on the 200-gauge metal film.

The lower substrate 100 can be made from silicon (Si), aluminum (Al2O3) or quartz, but it’s preferable that the lower sub-stratum 100 is made of glass. This is because glass is more suitable for sealing a white light source. You can make the metal film 200 from a conductive material such as chrome (Cr), titanium(Ti), nitride titan (TiN), or tungsten (W).

The catalytical metal film 300 acts as a catalyst for the formation of vertically aligned carbon Nanotubes 400. The catalytical metal film 300 is made of a metal material that acts as a catalyst to synthesize and grow the carbon nanotubes. For example, the catalytic metal film 300 may be formed of cobalt (Co), nickel (Ni), iron (Fe), yttrium (Y) or an alloy of at least two among them (for example, cobalt-nickel, cobalt-iron, cobalt-yttrium, nickel-iron, cobalt-iron or cobalt-nickel-yttrium).”

“The catalytic metal film 300 contains the vertically aligned carbon microtubes 400. Vertically growing carbon nanotubes 400 is possible from a carbon source that is applied to the catalytical metal film 300 using a chemicalvapor deposition method. The chemical vapor deposition method is used to grow the carbon nanotubes 400. Refer to FIGS. 6 to 10

“The carbon nanotubes400 are used for electron emission in an applied electrical field. A fluorescent body 800 is placed at the tip of the 400 carbon nanotubes. It faces the 400 carbon nanotubes at a distance of 400. On the back of the fluorescent-body 800 is a transparent electrode 700. The upper substrate 600, to which the transparent electrode 700 attaches, is mounted on spacers 500. It is vacuum sealed with lower substrate 100.

The transparent electrode 700 could be made of transparent conductive materials such as indium Tin Oxide (ITO). The fluorescent body 800 may be formed of a fluorescent material, for example, (3Ca3(PO4)2CaFCl/Sb,Mn), generating a white luminescence, or a combination of fluorescent materials including, for example, Y2O3:Eu, CeMaA11O19:Tb and BaMg2Al16O7:Eu, to generate a white luminescence by combining different emission spectrums. To reflect light from fluorescent body 800, the upper substrate 600 can be made of transparent material such as glass.

The white light source with such configuration is able to emit electrons when an electric field is created between the transparent electrode 700 and the metal film 200. The tip diameter of each carbon tube 400 is extremely small, which can make it possible to emit electrons very efficiently. This is in contrast to the length of carbon nanotubes 400.

According to this, the electric field between the transparent electrode 700 and the metal film 200 can be reduced. This means that even low voltage can be applied to the transparent electrode 700 or metal film 200, so that the carbon nanotubes 400 can emit electrons very effectively, an extremely high concentration of electric fields can be created at their tips. The carbon nanotubes can also be grown at very high numbers of electrons. This is why the electron density emitted by the carbon nanotubes 405 aligned at high densities is extremely high. Therefore, the emission current is high.”

The fluorescent body 800 is made glow by the emitted electrons. Transparent substrate 600 emits the radiated light. As mentioned above, because the electron emission efficiency and the emission current are high due to the emitted electrons, the electron density striking the fluorescent body 800 is large. The fluorescent body 800 produces a lot of light, which is why the fluorescent body 800 emits a lot of light.

“The white light source according the the first embodiment is compact and simple, but it can emit monochromatic high-luminance light, as described above. It can also operate at very low voltages or very low currents, due to its high electron emission efficiency. This white light source is suitable for general illumination, or, if very small, can be used to create portable illumination systems.

“With reference to FIGS. “With reference to FIGS. 2-5, an embodiment of a method for fabricating the white source according the first embodiment will be described in great detail.”

“FIG. “FIG. The lower substrate 100 is used to form the metal film 200. This thin layer allows for mass production. Although the lower substrate 100 can be made of many materials, it is preferred that it is made of glass. To form the metal film 200, you deposit a conductive material such as chrome, titanium or nitride titan, tungsten, or aluminiu to a thickness of 0.3-0.5?m. A method for forming thin films, such as thermal deposition or sputtering, is used to deposition the metal film 200.

The metal film 200 is used to form the catalytic metal films 300 and 400. The thickness of the catalytical metal film 300 is about several nanometers. It can be deposited on several hundred of nanometers. Preferably, it will be between 2-200 nm and 2-300 nm. A method for forming thin films, such as thermal deposition or sputtering, can be used to deposition the catalytic metal film 300.

“FIG. 3. Schematically illustrates the process of growing carbon nanotubes 400 using the catalytic metallic film 300. Catalytic metal 300 is used as a catalyst to grow a plurality carbon nanotubes 400. These carbon nanotubes are vertically aligned and spaced apart on the catalytical metal 300. The catalytic metallic film 300’s surface is grain boundary etched to separate 300 gram catalytical metal particles from 300. The surface of the 200-layer underlying metal film is thus exposed between the catalytic metal particles. The catalytical metal film 300 thus is made up of the independent catalytical metal particles.

“The carbon source is then provided on the catalytic metallic film 300 to grow carbon nanotubes from individual catalytical metal particles. The grain boundary etching rate and thickness of the initial catalytical metal film 300 can affect the size of each catalytical metal particle. You can adjust the size of each catalytical metal particle to alter the diameter of each carbon nanotube400. The catalytic metal particles that are formed through grain boundary etching are uniformly organized, so the carbon nanotubes grown 400 are also laid in lines.

“Here are the carbon nanotubes 400 that can be grown by using either a plasma or thermal chemical vapor deposition technique. The chemical vapor deposition method for growing the carbon nanotubes 400 will be discussed in detail later with reference to FIGS. 6 to 10

“FIG. 4. The step of installing spacers 500 onto the catalytic metallic film 300 is shown schematically. On the catalytic metallic film 500, a plurality of 500 spacers with a length between 100 and 700?m are placed. The spacers 500 are used to separate the fluorescent body (800 in FIG. 1), which will be later provided, from the tips 400 of carbon nanotubes 400 at a predetermined distance.

“FIG. “FIG. As an anode, the transparent electrode 700 is attached to transparent substrate 600. Transparent electrode 700 is made of transparent conductive materials such as ITO. The transparent electrode 700 is then attached to the fluorescent body 800. The fluorescent body 800 may be formed of a fluorescent material, for example, (3Ca3(PO4)2CaFCl/Sb,Mn), generating a white luminescence, or a combination of fluorescent materials including, for example, Y2O3:Eu, CeMaA11O19:Tb and BaMg2Al16O7:Eu, to generate a white luminescence by combining different emission spectrums.”

“The fluorescent body 800 is mounted on the upper substrate 600. The transparent electrode 700 is mounted on spacers 500 so that the fluorescent body 800’s surface faces the tips 400 of carbon nanotubes. The transparent upper substrate 600 is then vacuum sealed, while the lower substrate 100 is sealed.

“For the carbon-nanotubes 400 of a white light source, the tip diameter is very small, at several nanometers through many tens of nanometers. This allows for emission of electrons in an electric field with high efficiency, even at very low voltage.”

“With reference to FIGS. “With reference to FIGS. 6-10, a method for growing the carbon nanotubes 400 in fabricating a white light source according the present invention will also be described in detail.

“FIG. “FIG. FIGS. FIGS. 7-10 are sectional views that show the growth of carbon nanotubes in accordance with the present invention.

“Briefly, we will be describing the 400 vertically aligned carbon-nanotubes 400 in FIG. 3, can be grown in the same manner as in FIGS. 7 to 10 can be grown using a thermal chemical deposition apparatus, as shown in FIG. 6. This article will show how to vertically align carbon nanotubes 400 using thermal chemical vapour deposition. However, you can also use a plasma chemical vapor vapor deposition method to vertically align carbon nanotubes400.

“Referring FIG. “Referring to FIG. 3.) a large area. The catalytic metallic film 300 has a thickness of several hundred nanometers to several hundreds of nanometers. Preferably, it is between 2-200 nm and 2-200 nm.

“A substrate 6300 is used to form the catalytic metallic film 300. It is then mounted on a quartz vessel 6400. Then, it is loaded into a reaction furnace 6100. 6. The substrate 6300 is mounted on top of the quartz boat 6400 so that the surface 6350 on which the carbon-nanotubes 400 are formed faces away from the direction where a gas is supplied. This is to prevent impurities and residuals from adhering on the surface 6350 where the carbon nanotubes 400 are grown. It also makes the flow of reactive gas, which is supplied at the surface 6350 uniform.

“Here, pressure in the reaction furnace 6100 is maintained to atmospheric pressure or several hundred of mTorr through many Torr. The reaction furnace 6100 is heated using a resistance coil 6200 heating unit. An etching gas such ammonia (NH3), which allows grain-boundary etching of catalytic metal films 300, is then injected into it. The etching agent has the function of etching catalytic metallic film 300 along the grain boundaries. It is preferred that the ammonia gases be decomposed prior to reaching the substrate 6300, which is mounted on the quartz vessel 6400 in the reaction furnace6100.

“Referring FIGS. 7. and 8. The ammonia gas 7100 with reactivity etch the surface grain borders of the catalytic metallic film 300. It is preferred that grain boundary etching be performed before the 200-layer underlying metal film is exposed. The result is that catalytic metal particles 300 are separated from one another as shown in FIG. 8. Each of the 300 catalytic metal particles is 300? Nano-sized (from a few nm to several hundred nm). What is the size of the catalytical metal particles 300? You can adjust the thickness of the first catalytical metal film 300, ammonia gas supply during grain boundary etching, temperature, and time for the etching.

“The 300 nano-sized, independently isolated catalytical metal particles 300″ They are formed by etching 300 nm of the catalytic film 300 along grain boundaries to allow them to be microscopically distributed on 200 nm. What are the sizes and shapes for the 300 nano-sized catalytical metal particles 300? The etching conditions can affect the shapes and sizes of the catalytic metal particles 300? The catalytic metal particles 300 are used in an embodiment of the invention. Preferably, they are formed with a diameter of between 20-60 nm.”

“An example of using ammonia as a grain boundary gas has been presented, but hydrogen gas and a hydride gas can also be used. It is preferred to use ammonia as an etching agent. For approximately 10-30 minutes, ammonia gas is injected in the reaction furnace 6100 at an average flow rate of 80 standard cubic centimeters (sccm),

“Referring back to FIG. 8 once the catalytical metal particles 300 are formed? Once the catalytic metallic particles 300 are formed, the injections of decomposed ammonia gases 7100 and 8100 are stopped. A carbon source 8100 is then injected into reaction furnace 6100 to achieve the catalytical metal particles 300?. As the carbon source 8100, a hydrocarbon gas containing carbon dimers can be used. It is possible to use a hydrocarbon gas with less than 20 carbon atoms per mole, such as acetylene, ethylene, propylene, profane, or methane.

Hydrogen or an inert gas like argon may be injected into the reaction furnace 6100 along with the carbon source as a carrier gas. A hydride gas, for example may also be injected into the reaction furnace 6100 as a dilutant. A suitable ratio of an etching gas, such as hydrogen gas, ammonia gas or hydride, can be injected into the reaction furnace 6100 together with the carbon source gas. This will control the synthesizing reaction for the carbon nanotubes 400.

“The carbon source is injected into the reaction heater 6100 using a thermal chemical deposition apparatus, as shown in FIG. 6 is pyrolyzed into carbon units (e.g. C2H2). FIG. 9 and sorb on the catalytical metal particles 300? Or diffuse into the catalytical metal particles 300? When the carbon units come in contact with the surface of the catalytical metal particles 300?, they are transformed into carbon dimers, which generate hydrogen gas (H2).

“The carbon dimers absorb over the surfaces 300 of the catalytical metal particles 300?” Or diffuse into the catalytical metal particles 300? Each of the 300-gram catalytic metal particles reacts with each other. When supersaturated in carbon dimers, the carbon dimers react with each other, forming repeated hexagonal rings, similar to a honeycomb in two-dimensional views. The carbon dimers are then supplied to the catalytical metal particles 300. Continued growth of the catalytic metal particles 300? to form a wall of a honeycomb structure is observed. This process continues, creating a carbon nanotube 400 from the catalytical metal particle 300?. The carbon dimers are then supplied to the catalytical metal particles 300?. So that carbon nanotubes 400 may be grown. Each catalytic metal particle has a density of 300. When the density of each catalytic metal particle 300 is sufficient, the carbon nanotubes400, which are formed from the plurality od catalytical metal particles 300? push each other back, thus growing vertically.

“Meanwhile the growth of carbon nanotubes400 is continuing, and the carbon nutubes400 may have a bamboo structure as shown in FIG. 10.”

“The catalytical metal particles 300?” They are suitable for the growth of carbon nanotubes 400. They can be separated so that the carbon nanotubes 40 are not agglomerated, but can be formed independently. Also, the formation of carbon nanotubes 400 is occurring while amorphous carbon aggregates are not being formed. Carbon nanotubes 400 with high purity can be obtained. The carbon nanotubes 406 can also be made vertically aligned onto the lower substrate 100. You can also adjust the length of carbon nanotubes 400 by changing the supply conditions of the carbon source. This includes a gas flow rate or temperature change, as well as the reaction time.

“In the embodiment described above, the nano-sized catalytical metal particles are formed using a dry etching process with the thermal chemical deposition apparatus of FIG. They can also be formed using a wet-etching method. To put it another way, a substrate with a catalytic metallic film can be dipped in a wet Etchant, such as hydrogen fluoride (HF), diluted with water to form isolated, nano-sized catalytical metal particles. The wet etching method can also create isolated catalytical metal particles at low temperatures.

“In the present embodiment, a horizontal-type thermal chemical deposition apparatus is used for growing catalytic metal particles or carbon nanotubes. However, a vertical, in-line, conveyor type or conveyor type thermal vapor deposition device can also be used. A plasma chemical vapor deposit apparatus is also possible. The plasma chemical vapor apparatus can be used at low temperatures and can be adjusted to adjust the reaction.

“FIG. “FIG. 11. This is a sectional schematic view to explain a white light source according a second embodiment. The same reference numbers denote the same member in the first and second embodiments.

The second embodiment of the invention’s white light source includes a 200-gauge metal film used as a cathode on a lower substrate 100, and a 300-gauge catalytical metal film 300 on the 200-gauge metal film 200. Between the metal film 200, and the lower substrate 100, a reaction preventing film 150 made of an insulating substance such as silicon oxide or aluminum may be added. The reaction preventing screen 150 is an insulating material, such as silicon oxide or alumina, that prevents the reaction between the lower substrate 100, the metal film 200 and each other. It has a thickness of approximately 0.3-0.5?m.

On the metal film 200, a catalytic metal film 300 has been formed. On the catalytical metal film 300, an insulation film pattern 350 with openings like holes is provided. This allows you to selectively expose the catalytical metal film 300’s surface. The insulation film 350 is made to a thickness of approximately 1.0-3.0?m. The insulation film pattern 350 identifies the locations where carbon nanotubes 400 can be grown.

The catalytic metal film 300 is exposed through the openings and contains the carbon nanotubes 400 that have been grown vertically by chemical vapor deposition. For the emission of electrons in an electrical field, the carbon nanotubes 400 can be used. To face the 400 carbon nanotubes’ tips, a fluorescent body 800 is available. On the back of the fluorescent 800 is a transparent electrode 700. The upper substrate 600, to which the transparent electrode 700 will be attached, is mounted on spacers 500. It is vacuum sealed with the lower substrate 100. The insulation film pattern 350 supports the spacers 500. The fluorescent body 800 should be patterned so that the transparent electrode 700 is exposed to the spacers 500.

“Accordingly to the second embodiment, the carbon nanotubes400 can be grouped and each group can form a single cell.”

“With reference to FIGS. “With reference to FIGS. 12 through 14, we will describe in detail an embodiment of a method for fabricating the white source according the second embodiment.

“FIG. “FIG. 12 shows how to form the insulation film pattern 350 on lower substrate 100. The lower substrate 100 is used to form the metal film 200 as a cathode. It has a large surface. Although the lower substrate 100 can be made of different materials as mentioned above, it is preferable to be made of glass. To form the metal film 200, you deposit chrome, titanium and nitride titan to a thickness of 0.3-0.5?m.

“The reaction preventing screen 150 can be placed below the metal movie 200 to prevent the reaction between the lower substrate 100 and the metal film 200. The lower substrate 100 can be made of silicon, quartz or glass. The silicon in the lower substrate 100 may react with the 200 metal film during a thermal process, such as a chemicalvapor deposition process to form carbon nanotubes. The reaction preventing film 150 can be used to prevent this reaction. The reaction preventing film 150 is made of an insulating material, such as silicon oxide, with a thickness of approximately 0.3-0.5?m.

The metal film 200 is then coated with the catalytical metal film 300. This can be used as a catalyst for the growth of the carbon nanotubes 400. The thickness of the catalytical metal film 300 can be deposited from several nanometers to several hundred of nanometers to, preferably, between 20 and 100 nm. A method for forming thin films, such as thermal deposition or sputtering, can be used to depose the catalytic metal film 300.

The insulation film is then patterned using photolithography. This forms the insulation pattern 350, while exposing the 300-pound catalytic metal film underneath. A photoresist film (not illustrated) can be deposited to approximately 1.5-2.0 m thickness and then exposed and developed. This forms a photoresist pattern that selectively exposes the insulation film. The insulation film is then selectively etched using a photoresist template as an etching pattern, thus forming the insulation pattern 350. This selectively exposes the 300-layer catalytic metal film. The openings in the insulation film 350 could be microscopic holes with a diameter between 1.0 and 5.0?m. The distance between holes can be from 3.0 to 15.0 m. After that, the photoresist pattern can be removed using a stripping process.

“FIG. 13 shows the steps involved in growing carbon nanotubes 400 vertically on the catalytic metallic film 300. Selectively grown carbon nanotubes 400 that are vertically aligned on the catalytical metal film 300, the film is then exposed through the openings in the insulation film 350. Chemical vapor deposition is used as described in FIGS. 6-10 These carbon nanotubes 400 are easily arranged in lines and can also be vertically grown.

“FIG. 14 shows how to mount the 500 spacers on the insulation film 350. On the insulation film 350 are mounted a plurality of 500 spacers with a length of approximately 100-700 mm. The spacers 500 are used to separate the fluorescent body 800 from the tips and carbon nanotubes 400.

“The transparent electrode 700 is then attached to the transparent substrate 600. This could be a glass substrate. Transparent electrode 700 is made of transparent conductive materials such as ITO. The transparent electrode 700 is then attached to the fluorescent body 800. The fluorescent body 800 may be formed of a fluorescent material, for example, (3Ca3(PO4)2CaFCl/Sb,Mn), generating a white luminescence, or a combination of fluorescent materials including, for example, Y2O3:Eu, CeMaA11O19:Tb and BaMg2Al16O7:Eu, to generate a white luminescence by combining different emission spectrums.”

“The fluorescent body 800 is attached to the separated upper substrate 600. The transparent electrode 700 is mounted to the spacers 500 so that the transparent electrode 700 and fluorescent body 800 face the tips. The transparent upper substrate 600 is vacuum sealed, and the lower substrate 100 is sealed.

The present invention is capable of providing a white light source. This can be achieved by using carbon nanotubes having tips with very small diameters as electric field electron emission tip tips. The present invention is able to provide excellent luminance through the use of carbon nanotubes that are vertically aligned and have a high density tip per unit area. The manufacturing process of the white light source is simplified, which improves the reliability and yield of the products. This allows for the production of next-generation white light sources that are highly efficient and power-saving, which can replace existing fluorescent lamps or glow lamps. The present invention allows for the creation of a white light source that is extremely small and can be carried around as a portable source.

“Even though the invention has been described in terms of particular embodiments, it will be obvious to someone of ordinary skill that modifications to these embodiments can be made without departing form the spirit and scope.

Summary for “White light source using carbon Nanotubes and the fabrication method thereof”

“1. “1.

“The invention is a white light source and, more specifically, a method for manufacturing a white source with an excellent luminous efficacy.”

“2. “2.

A fluorescent lamp is an example of a representative white light source. Fluorescent lamps emit light from a fluorescent body through a discharge effect. Low luminance is a drawback to this fluorescent lamp. It is also difficult to reduce the size of the fluorescent lamp. The fluorescent lamp’s luminance decreases with time. The fluorescent lamp’s reliability and stability are affected, and its life span is also reduced.

“To address the above problems, the present invention provides a white light source with an excellent electron emission efficiency in an electric field to obtain a large emission current even when applied voltage is low. It also has a high density electron emitters per area to exhibit excellent luminance. The fabrication method of this light source is also provided.”

The present invention includes a white light source that includes a metal substrate as a cathode. A catalytic metallic film is formed on the lower substrate. Carbon nanotubes are attached to the transparent substrate. To the transparent electrode, a fluorescent body is attached. The transparent substrate is mounted on the spacers so that the fluorescent body faces carbon nanotubes.

The catalytic metallic film can be made of nano-sized catalytical metal particles. Carbon nanotubes can be vertically grown by chemical vapor deposition from each catalytical metal particle. Here, the catalytic metal film may be formed of cobalt, nickel, iron, yttrium or an alloy of at least two of them, and the fluorescent body may be formed of (3Ca3(PO4)2CaFCl/Sb,Mn), generating a white luminescence, or a combination of Y2O3:Eu, CeMaA11O19:Tb and BaMg2Al16O7:Eu, to generate a white luminescence by combining different emission spectrums.”

“The white light source could also include an insulation film pattern with openings that selectively expose the catalytic metallic film. The carbon nanotubes can be placed on portions of the catalytic metallic film that are exposed through these openings. The insulation film may have spacers.

“The invention also provides a method for fabricating a white-light source. On a lower substrate, a metal film is formed that can be used as a cathode. The metal film forms a catalytical metal film. The catalytic metallic film is used to grow carbon nanotubes that emit electrons in an applied electrical field. The catalytical metal film is fitted with a spacer. The spacer is a transparent upper substrate with a transparent electrode that has a fluorescent body. The transparent upper substrate is sealed to the lower substrate.

An insulating material can also be used to form a reaction-preventing film. This prevents the reaction between the lower substrate, the metal film and the next step of making the metal film. The catalytical metal film is created by depositing the catalytical metal film and then etching the deposited catalyst metal film to separate the catalytical metal film into tiny catalytical metal particles. Each catalytic metal particle is used to grow carbon nanotubes that are vertically aligned onto the substrate using chemical vapor deposition.

“Catalytic metal films may contain cobalt, nickel or iron as well as yttrium, or an alloy of at most two of these elements. The catalytical metal film can also be coated with an insulation film pattern that has openings that selectively expose the catalytical metal film. The carbon nanotubes can be located in the exposed portions of the catalytical metal film through these openings. Spacers can also be mounted on this insulation film pattern.

“The invention is capable of providing a white light source that can be very small and portable and has high efficiency and power saving.”

“The following describes the embodiments of the invention in detail, with reference to the attached illustrations. The present invention does not limit itself to the following embodiments. Many variations are possible within its scope and spirit. To better explain the invention to those skilled in the art, the embodiments of the invention have been provided. The drawings show members in exaggerated shapes. The same reference numbers denote the same members. A film described as being on another layer or a semiconductor substrate can also be on the same film.

The present invention provides a white-light source made from carbon nanotubes, and a method for fabricating them. A carbon nanotube can be microscopically made so that one carbon element is combined and three neighboring carbon elements. This creates a hexagonal-shaped ring by the combination of the carbon molecules. The hexagonal ring is then formed by rolling a plan composed of repeated hexagonal rings, like a honeycomb, to form a cylindrical shape. The cylindrical structure has a diameter of several nanometers to several tens or more nanometers and a length that is several tens to several thousands of feet longer than its diameter.

According to this, the tip of a carbon-nanotube’s tip has a diameter of several micrometers. It can also be a few tens of nanometers in length. This allows for high electron emission efficiency when applied electric fields are applied. A low voltage can produce a high amount of emission current. Carbon nanotubes can also be grown at a high density per unit area, which allows for excellent luminescence.

“The present invention will be described in greater detail with the help of the accompanying drawings. These drawings show preferred embodiments.”

“FIG. “FIG. Referring to FIG. Referring to FIG. 1, the white light source according the first embodiment is a 200-gauge metal film that acts as a cathode on a 100-gauge lower substrate and 300-gauge catalytic metal films on the 200-gauge metal film.

The lower substrate 100 can be made from silicon (Si), aluminum (Al2O3) or quartz, but it’s preferable that the lower sub-stratum 100 is made of glass. This is because glass is more suitable for sealing a white light source. You can make the metal film 200 from a conductive material such as chrome (Cr), titanium(Ti), nitride titan (TiN), or tungsten (W).

The catalytical metal film 300 acts as a catalyst for the formation of vertically aligned carbon Nanotubes 400. The catalytical metal film 300 is made of a metal material that acts as a catalyst to synthesize and grow the carbon nanotubes. For example, the catalytic metal film 300 may be formed of cobalt (Co), nickel (Ni), iron (Fe), yttrium (Y) or an alloy of at least two among them (for example, cobalt-nickel, cobalt-iron, cobalt-yttrium, nickel-iron, cobalt-iron or cobalt-nickel-yttrium).”

“The catalytic metal film 300 contains the vertically aligned carbon microtubes 400. Vertically growing carbon nanotubes 400 is possible from a carbon source that is applied to the catalytical metal film 300 using a chemicalvapor deposition method. The chemical vapor deposition method is used to grow the carbon nanotubes 400. Refer to FIGS. 6 to 10

“The carbon nanotubes400 are used for electron emission in an applied electrical field. A fluorescent body 800 is placed at the tip of the 400 carbon nanotubes. It faces the 400 carbon nanotubes at a distance of 400. On the back of the fluorescent-body 800 is a transparent electrode 700. The upper substrate 600, to which the transparent electrode 700 attaches, is mounted on spacers 500. It is vacuum sealed with lower substrate 100.

The transparent electrode 700 could be made of transparent conductive materials such as indium Tin Oxide (ITO). The fluorescent body 800 may be formed of a fluorescent material, for example, (3Ca3(PO4)2CaFCl/Sb,Mn), generating a white luminescence, or a combination of fluorescent materials including, for example, Y2O3:Eu, CeMaA11O19:Tb and BaMg2Al16O7:Eu, to generate a white luminescence by combining different emission spectrums. To reflect light from fluorescent body 800, the upper substrate 600 can be made of transparent material such as glass.

The white light source with such configuration is able to emit electrons when an electric field is created between the transparent electrode 700 and the metal film 200. The tip diameter of each carbon tube 400 is extremely small, which can make it possible to emit electrons very efficiently. This is in contrast to the length of carbon nanotubes 400.

According to this, the electric field between the transparent electrode 700 and the metal film 200 can be reduced. This means that even low voltage can be applied to the transparent electrode 700 or metal film 200, so that the carbon nanotubes 400 can emit electrons very effectively, an extremely high concentration of electric fields can be created at their tips. The carbon nanotubes can also be grown at very high numbers of electrons. This is why the electron density emitted by the carbon nanotubes 405 aligned at high densities is extremely high. Therefore, the emission current is high.”

The fluorescent body 800 is made glow by the emitted electrons. Transparent substrate 600 emits the radiated light. As mentioned above, because the electron emission efficiency and the emission current are high due to the emitted electrons, the electron density striking the fluorescent body 800 is large. The fluorescent body 800 produces a lot of light, which is why the fluorescent body 800 emits a lot of light.

“The white light source according the the first embodiment is compact and simple, but it can emit monochromatic high-luminance light, as described above. It can also operate at very low voltages or very low currents, due to its high electron emission efficiency. This white light source is suitable for general illumination, or, if very small, can be used to create portable illumination systems.

“With reference to FIGS. “With reference to FIGS. 2-5, an embodiment of a method for fabricating the white source according the first embodiment will be described in great detail.”

“FIG. “FIG. The lower substrate 100 is used to form the metal film 200. This thin layer allows for mass production. Although the lower substrate 100 can be made of many materials, it is preferred that it is made of glass. To form the metal film 200, you deposit a conductive material such as chrome, titanium or nitride titan, tungsten, or aluminiu to a thickness of 0.3-0.5?m. A method for forming thin films, such as thermal deposition or sputtering, is used to deposition the metal film 200.

The metal film 200 is used to form the catalytic metal films 300 and 400. The thickness of the catalytical metal film 300 is about several nanometers. It can be deposited on several hundred of nanometers. Preferably, it will be between 2-200 nm and 2-300 nm. A method for forming thin films, such as thermal deposition or sputtering, can be used to deposition the catalytic metal film 300.

“FIG. 3. Schematically illustrates the process of growing carbon nanotubes 400 using the catalytic metallic film 300. Catalytic metal 300 is used as a catalyst to grow a plurality carbon nanotubes 400. These carbon nanotubes are vertically aligned and spaced apart on the catalytical metal 300. The catalytic metallic film 300’s surface is grain boundary etched to separate 300 gram catalytical metal particles from 300. The surface of the 200-layer underlying metal film is thus exposed between the catalytic metal particles. The catalytical metal film 300 thus is made up of the independent catalytical metal particles.

“The carbon source is then provided on the catalytic metallic film 300 to grow carbon nanotubes from individual catalytical metal particles. The grain boundary etching rate and thickness of the initial catalytical metal film 300 can affect the size of each catalytical metal particle. You can adjust the size of each catalytical metal particle to alter the diameter of each carbon nanotube400. The catalytic metal particles that are formed through grain boundary etching are uniformly organized, so the carbon nanotubes grown 400 are also laid in lines.

“Here are the carbon nanotubes 400 that can be grown by using either a plasma or thermal chemical vapor deposition technique. The chemical vapor deposition method for growing the carbon nanotubes 400 will be discussed in detail later with reference to FIGS. 6 to 10

“FIG. 4. The step of installing spacers 500 onto the catalytic metallic film 300 is shown schematically. On the catalytic metallic film 500, a plurality of 500 spacers with a length between 100 and 700?m are placed. The spacers 500 are used to separate the fluorescent body (800 in FIG. 1), which will be later provided, from the tips 400 of carbon nanotubes 400 at a predetermined distance.

“FIG. “FIG. As an anode, the transparent electrode 700 is attached to transparent substrate 600. Transparent electrode 700 is made of transparent conductive materials such as ITO. The transparent electrode 700 is then attached to the fluorescent body 800. The fluorescent body 800 may be formed of a fluorescent material, for example, (3Ca3(PO4)2CaFCl/Sb,Mn), generating a white luminescence, or a combination of fluorescent materials including, for example, Y2O3:Eu, CeMaA11O19:Tb and BaMg2Al16O7:Eu, to generate a white luminescence by combining different emission spectrums.”

“The fluorescent body 800 is mounted on the upper substrate 600. The transparent electrode 700 is mounted on spacers 500 so that the fluorescent body 800’s surface faces the tips 400 of carbon nanotubes. The transparent upper substrate 600 is then vacuum sealed, while the lower substrate 100 is sealed.

“For the carbon-nanotubes 400 of a white light source, the tip diameter is very small, at several nanometers through many tens of nanometers. This allows for emission of electrons in an electric field with high efficiency, even at very low voltage.”

“With reference to FIGS. “With reference to FIGS. 6-10, a method for growing the carbon nanotubes 400 in fabricating a white light source according the present invention will also be described in detail.

“FIG. “FIG. FIGS. FIGS. 7-10 are sectional views that show the growth of carbon nanotubes in accordance with the present invention.

“Briefly, we will be describing the 400 vertically aligned carbon-nanotubes 400 in FIG. 3, can be grown in the same manner as in FIGS. 7 to 10 can be grown using a thermal chemical deposition apparatus, as shown in FIG. 6. This article will show how to vertically align carbon nanotubes 400 using thermal chemical vapour deposition. However, you can also use a plasma chemical vapor vapor deposition method to vertically align carbon nanotubes400.

“Referring FIG. “Referring to FIG. 3.) a large area. The catalytic metallic film 300 has a thickness of several hundred nanometers to several hundreds of nanometers. Preferably, it is between 2-200 nm and 2-200 nm.

“A substrate 6300 is used to form the catalytic metallic film 300. It is then mounted on a quartz vessel 6400. Then, it is loaded into a reaction furnace 6100. 6. The substrate 6300 is mounted on top of the quartz boat 6400 so that the surface 6350 on which the carbon-nanotubes 400 are formed faces away from the direction where a gas is supplied. This is to prevent impurities and residuals from adhering on the surface 6350 where the carbon nanotubes 400 are grown. It also makes the flow of reactive gas, which is supplied at the surface 6350 uniform.

“Here, pressure in the reaction furnace 6100 is maintained to atmospheric pressure or several hundred of mTorr through many Torr. The reaction furnace 6100 is heated using a resistance coil 6200 heating unit. An etching gas such ammonia (NH3), which allows grain-boundary etching of catalytic metal films 300, is then injected into it. The etching agent has the function of etching catalytic metallic film 300 along the grain boundaries. It is preferred that the ammonia gases be decomposed prior to reaching the substrate 6300, which is mounted on the quartz vessel 6400 in the reaction furnace6100.

“Referring FIGS. 7. and 8. The ammonia gas 7100 with reactivity etch the surface grain borders of the catalytic metallic film 300. It is preferred that grain boundary etching be performed before the 200-layer underlying metal film is exposed. The result is that catalytic metal particles 300 are separated from one another as shown in FIG. 8. Each of the 300 catalytic metal particles is 300? Nano-sized (from a few nm to several hundred nm). What is the size of the catalytical metal particles 300? You can adjust the thickness of the first catalytical metal film 300, ammonia gas supply during grain boundary etching, temperature, and time for the etching.

“The 300 nano-sized, independently isolated catalytical metal particles 300″ They are formed by etching 300 nm of the catalytic film 300 along grain boundaries to allow them to be microscopically distributed on 200 nm. What are the sizes and shapes for the 300 nano-sized catalytical metal particles 300? The etching conditions can affect the shapes and sizes of the catalytic metal particles 300? The catalytic metal particles 300 are used in an embodiment of the invention. Preferably, they are formed with a diameter of between 20-60 nm.”

“An example of using ammonia as a grain boundary gas has been presented, but hydrogen gas and a hydride gas can also be used. It is preferred to use ammonia as an etching agent. For approximately 10-30 minutes, ammonia gas is injected in the reaction furnace 6100 at an average flow rate of 80 standard cubic centimeters (sccm),

“Referring back to FIG. 8 once the catalytical metal particles 300 are formed? Once the catalytic metallic particles 300 are formed, the injections of decomposed ammonia gases 7100 and 8100 are stopped. A carbon source 8100 is then injected into reaction furnace 6100 to achieve the catalytical metal particles 300?. As the carbon source 8100, a hydrocarbon gas containing carbon dimers can be used. It is possible to use a hydrocarbon gas with less than 20 carbon atoms per mole, such as acetylene, ethylene, propylene, profane, or methane.

Hydrogen or an inert gas like argon may be injected into the reaction furnace 6100 along with the carbon source as a carrier gas. A hydride gas, for example may also be injected into the reaction furnace 6100 as a dilutant. A suitable ratio of an etching gas, such as hydrogen gas, ammonia gas or hydride, can be injected into the reaction furnace 6100 together with the carbon source gas. This will control the synthesizing reaction for the carbon nanotubes 400.

“The carbon source is injected into the reaction heater 6100 using a thermal chemical deposition apparatus, as shown in FIG. 6 is pyrolyzed into carbon units (e.g. C2H2). FIG. 9 and sorb on the catalytical metal particles 300? Or diffuse into the catalytical metal particles 300? When the carbon units come in contact with the surface of the catalytical metal particles 300?, they are transformed into carbon dimers, which generate hydrogen gas (H2).

“The carbon dimers absorb over the surfaces 300 of the catalytical metal particles 300?” Or diffuse into the catalytical metal particles 300? Each of the 300-gram catalytic metal particles reacts with each other. When supersaturated in carbon dimers, the carbon dimers react with each other, forming repeated hexagonal rings, similar to a honeycomb in two-dimensional views. The carbon dimers are then supplied to the catalytical metal particles 300. Continued growth of the catalytic metal particles 300? to form a wall of a honeycomb structure is observed. This process continues, creating a carbon nanotube 400 from the catalytical metal particle 300?. The carbon dimers are then supplied to the catalytical metal particles 300?. So that carbon nanotubes 400 may be grown. Each catalytic metal particle has a density of 300. When the density of each catalytic metal particle 300 is sufficient, the carbon nanotubes400, which are formed from the plurality od catalytical metal particles 300? push each other back, thus growing vertically.

“Meanwhile the growth of carbon nanotubes400 is continuing, and the carbon nutubes400 may have a bamboo structure as shown in FIG. 10.”

“The catalytical metal particles 300?” They are suitable for the growth of carbon nanotubes 400. They can be separated so that the carbon nanotubes 40 are not agglomerated, but can be formed independently. Also, the formation of carbon nanotubes 400 is occurring while amorphous carbon aggregates are not being formed. Carbon nanotubes 400 with high purity can be obtained. The carbon nanotubes 406 can also be made vertically aligned onto the lower substrate 100. You can also adjust the length of carbon nanotubes 400 by changing the supply conditions of the carbon source. This includes a gas flow rate or temperature change, as well as the reaction time.

“In the embodiment described above, the nano-sized catalytical metal particles are formed using a dry etching process with the thermal chemical deposition apparatus of FIG. They can also be formed using a wet-etching method. To put it another way, a substrate with a catalytic metallic film can be dipped in a wet Etchant, such as hydrogen fluoride (HF), diluted with water to form isolated, nano-sized catalytical metal particles. The wet etching method can also create isolated catalytical metal particles at low temperatures.

“In the present embodiment, a horizontal-type thermal chemical deposition apparatus is used for growing catalytic metal particles or carbon nanotubes. However, a vertical, in-line, conveyor type or conveyor type thermal vapor deposition device can also be used. A plasma chemical vapor deposit apparatus is also possible. The plasma chemical vapor apparatus can be used at low temperatures and can be adjusted to adjust the reaction.

“FIG. “FIG. 11. This is a sectional schematic view to explain a white light source according a second embodiment. The same reference numbers denote the same member in the first and second embodiments.

The second embodiment of the invention’s white light source includes a 200-gauge metal film used as a cathode on a lower substrate 100, and a 300-gauge catalytical metal film 300 on the 200-gauge metal film 200. Between the metal film 200, and the lower substrate 100, a reaction preventing film 150 made of an insulating substance such as silicon oxide or aluminum may be added. The reaction preventing screen 150 is an insulating material, such as silicon oxide or alumina, that prevents the reaction between the lower substrate 100, the metal film 200 and each other. It has a thickness of approximately 0.3-0.5?m.

On the metal film 200, a catalytic metal film 300 has been formed. On the catalytical metal film 300, an insulation film pattern 350 with openings like holes is provided. This allows you to selectively expose the catalytical metal film 300’s surface. The insulation film 350 is made to a thickness of approximately 1.0-3.0?m. The insulation film pattern 350 identifies the locations where carbon nanotubes 400 can be grown.

The catalytic metal film 300 is exposed through the openings and contains the carbon nanotubes 400 that have been grown vertically by chemical vapor deposition. For the emission of electrons in an electrical field, the carbon nanotubes 400 can be used. To face the 400 carbon nanotubes’ tips, a fluorescent body 800 is available. On the back of the fluorescent 800 is a transparent electrode 700. The upper substrate 600, to which the transparent electrode 700 will be attached, is mounted on spacers 500. It is vacuum sealed with the lower substrate 100. The insulation film pattern 350 supports the spacers 500. The fluorescent body 800 should be patterned so that the transparent electrode 700 is exposed to the spacers 500.

“Accordingly to the second embodiment, the carbon nanotubes400 can be grouped and each group can form a single cell.”

“With reference to FIGS. “With reference to FIGS. 12 through 14, we will describe in detail an embodiment of a method for fabricating the white source according the second embodiment.

“FIG. “FIG. 12 shows how to form the insulation film pattern 350 on lower substrate 100. The lower substrate 100 is used to form the metal film 200 as a cathode. It has a large surface. Although the lower substrate 100 can be made of different materials as mentioned above, it is preferable to be made of glass. To form the metal film 200, you deposit chrome, titanium and nitride titan to a thickness of 0.3-0.5?m.

“The reaction preventing screen 150 can be placed below the metal movie 200 to prevent the reaction between the lower substrate 100 and the metal film 200. The lower substrate 100 can be made of silicon, quartz or glass. The silicon in the lower substrate 100 may react with the 200 metal film during a thermal process, such as a chemicalvapor deposition process to form carbon nanotubes. The reaction preventing film 150 can be used to prevent this reaction. The reaction preventing film 150 is made of an insulating material, such as silicon oxide, with a thickness of approximately 0.3-0.5?m.

The metal film 200 is then coated with the catalytical metal film 300. This can be used as a catalyst for the growth of the carbon nanotubes 400. The thickness of the catalytical metal film 300 can be deposited from several nanometers to several hundred of nanometers to, preferably, between 20 and 100 nm. A method for forming thin films, such as thermal deposition or sputtering, can be used to depose the catalytic metal film 300.

The insulation film is then patterned using photolithography. This forms the insulation pattern 350, while exposing the 300-pound catalytic metal film underneath. A photoresist film (not illustrated) can be deposited to approximately 1.5-2.0 m thickness and then exposed and developed. This forms a photoresist pattern that selectively exposes the insulation film. The insulation film is then selectively etched using a photoresist template as an etching pattern, thus forming the insulation pattern 350. This selectively exposes the 300-layer catalytic metal film. The openings in the insulation film 350 could be microscopic holes with a diameter between 1.0 and 5.0?m. The distance between holes can be from 3.0 to 15.0 m. After that, the photoresist pattern can be removed using a stripping process.

“FIG. 13 shows the steps involved in growing carbon nanotubes 400 vertically on the catalytic metallic film 300. Selectively grown carbon nanotubes 400 that are vertically aligned on the catalytical metal film 300, the film is then exposed through the openings in the insulation film 350. Chemical vapor deposition is used as described in FIGS. 6-10 These carbon nanotubes 400 are easily arranged in lines and can also be vertically grown.

“FIG. 14 shows how to mount the 500 spacers on the insulation film 350. On the insulation film 350 are mounted a plurality of 500 spacers with a length of approximately 100-700 mm. The spacers 500 are used to separate the fluorescent body 800 from the tips and carbon nanotubes 400.

“The transparent electrode 700 is then attached to the transparent substrate 600. This could be a glass substrate. Transparent electrode 700 is made of transparent conductive materials such as ITO. The transparent electrode 700 is then attached to the fluorescent body 800. The fluorescent body 800 may be formed of a fluorescent material, for example, (3Ca3(PO4)2CaFCl/Sb,Mn), generating a white luminescence, or a combination of fluorescent materials including, for example, Y2O3:Eu, CeMaA11O19:Tb and BaMg2Al16O7:Eu, to generate a white luminescence by combining different emission spectrums.”

“The fluorescent body 800 is attached to the separated upper substrate 600. The transparent electrode 700 is mounted to the spacers 500 so that the transparent electrode 700 and fluorescent body 800 face the tips. The transparent upper substrate 600 is vacuum sealed, and the lower substrate 100 is sealed.

The present invention is capable of providing a white light source. This can be achieved by using carbon nanotubes having tips with very small diameters as electric field electron emission tip tips. The present invention is able to provide excellent luminance through the use of carbon nanotubes that are vertically aligned and have a high density tip per unit area. The manufacturing process of the white light source is simplified, which improves the reliability and yield of the products. This allows for the production of next-generation white light sources that are highly efficient and power-saving, which can replace existing fluorescent lamps or glow lamps. The present invention allows for the creation of a white light source that is extremely small and can be carried around as a portable source.

“Even though the invention has been described in terms of particular embodiments, it will be obvious to someone of ordinary skill that modifications to these embodiments can be made without departing form the spirit and scope.

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