KR100634856B1 - Method for making the electron emitter of carbonnanotubes using metal compounds - Google Patents

Abstract

According to the present invention, carbon nanotubes may be mixed together on a substrate using a metal, an alloy, a metal compound, etc., having a size of micrometers (nm) to nanometers (nm), or coated on a carbon nanotube thin film substrate and melted. After the compound of the present invention relates to a method for producing an electron emission source through heat and plasma post-treatment.

The carbon nanotube electron emission source according to the present invention may be surrounded by the metal outer wall of the tube together with the adhesion between the carbon nanotube and the substrate, thereby extending the life of the tip, as well as pretreatment and post-treatment for optimizing the field emission. It can be used as a carbon nanotube electron emission source of various forms such as wire, bar, and plate by the mixing process of metals, alloys and metal compounds. Can be.

Carbon nanotube, electron emission source, metal compound, heat treatment, post treatment

Description

Method for making the electron emitter of carbonnanotubes using metal compounds}             

1 is a cross-sectional view showing a manufacturing process of a conventional carbon nanotube field emission device;

2 is a schematic diagram of RTCVD used for the growth of carbon nanotubes according to the present invention;

3 is a process chart for the growth of carbon nanotubes of FIG.

4A is a view illustrating a process of growing carbon nanotubes by a conventional CVD method;

Figure 4b is a view showing a process of applying a metal powder on the carbon nanotubes of Figure 4a,

Figure 4c is a view showing the RTCVD equipment for high temperature heat treatment of the composition of Figure 4b in a gas atmosphere,

FIG. 4D illustrates a plasma CVD apparatus for plasma post-processing the constituent of FIG. 4B in a gaseous atmosphere. FIG.

5a and 5b is a view showing a molten state of carbon nanotubes and metal after the heat treatment or plasma post-treatment of the components of Figure 4b in a gas atmosphere,

6 is a view showing a mixed state of carbon nanotubes and a metal powder on a substrate of the present invention,

7 is a view showing a molten state of carbon nanotubes and a metal after the components of FIG. 6 are subjected to high temperature heat treatment or plasma post-treatment in a gas atmosphere;

8 is a scanning electron microscopy (SEM) photograph of the carbon nanotube thin film according to the first embodiment of the present invention;

9 is a SEM (scanning electron microscopy) photograph of the heat treatment of the carbon nanotube thin film according to the first embodiment of the present invention at 950 ℃,

10 is a SEM (scanning electron microscopy) photograph of the heat treatment of the carbon nanotube thin film according to the first embodiment of the present invention at 900 ℃,

11 is a scanning electron microscopy (SEM) photograph of a carbon nanotube thin film according to a second embodiment of the present invention;

12 is a scanning electron microscopy (SEM) photograph of the carbon nanotube thin film according to the second embodiment of the present invention after heat treatment at 950 ° C.

  Explanation of symbols on the main parts of the drawings

10 chamber 20 substrate

30: carbon nanotube 40: metal powder

50: plasma 60, 70: metal melting layer

80: hybrid melted layer

The present invention relates to a method for producing a carbon nanotube electron emission source, and more particularly to a metal, an alloy and a metal compound and a compound of carbon nanotubes by heat treatment, and then an electron emission source through a thermal and plasma post-treatment process It relates to a method of manufacturing.

Carbon nanotubes are "nanometers (nanometers: 1 billionth of a meter) in the form of cylindrical (tube) materials made of carbon atoms." In other words, the carbon plane, which has three carbon atoms bonded together and has a honeycomb structure, is rolled up to form a tube.

In general, the carbon electron emission layer of the electron emission source using the field emission characteristics of carbon nanotubes is made by a thin film process by CVD (Chemical Vapor Deposition) method or a thick film process by paste printing. The carbon nanotube electron emission source has a high field emission rate, and the emitted current can be controlled by voltage. Therefore, the field emission cathode is applied to an electron generating device such as a field emission display (FED) and an electron gun. Therefore, selective growth (adjustment of density, diameter, length) is a major research variable for high and stable current emission of carbon nanotube electron emission sources, and studies involving proper pretreatment and plasma posttreatment have been conducted.

In the field emission type lighting apparatus using carbon nanotubes disclosed in Korean Patent Laid-Open Publication No. 2003-0081997, an Indium Tin Oxide (ITO) layer is coated inside a cylindrical substrate 4 used as an anode, as shown in FIG. The phosphor layer is coated on the ITO layer, and the carbon nanotubes (3), which are oxidized and cut by using electrophoresis, are arranged to be close to the vertical in the metal wire (1) used as the cathode. After the metal 3 is tightly bonded between the tube 3 and the metal wire 1 with the fine metal particles 2 to minimize the contact resistance, the vacuum between the cylindrical substrate 4 and the metal wire 1 is changed to Ep &. P process is introduced.

By the way, such a conventional process method involves pretreatment of the catalyst metal layer for the selective growth of uniform carbon nanotubes 3, and thus the direct bonding between the carbon nanotubes 3 and the substrate 4 is a catalytic metal. It's beyond the limits of its role. In addition, post-treatment environments such as plasma and heat treatment of carbon nanotubes (3) thin film for high field emission is also a problem that maintains adhesion or adhesion to the substrate (4).

Accordingly, the present invention has been conceived to solve the conventional problems as described above, and an object of the present invention maintains a strong adhesion to melt in close contact with a medium, such as carbon nanotubes and between the metal, alloy and metal compound substrate At the same time, the present invention provides a method for producing a carbon nanotube electron emission source using a metal compound that optimizes field emission of carbon nanotubes by expanding post-treatment conditions such as plasma and high temperature heat treatment.

It is another object of the present invention that the composition of metals, alloys and metal compounds with carbon nanotubes is electron emission of various types of geometric shapes such as wires, bars and plates. The present invention provides a method for producing a carbon nanotube electron emission source using a metal compound which can easily produce various types of carbon nanotube electron emission sources as the layer is completed.

In order to achieve the above object, a method for producing a carbon nanotube electron emission source using a metal compound according to the present invention includes a micrometer (μm) on a carbon nanotube thin film grown on a metal substrate by a method such as plasma CVD or RTCVD. Forming a compound with the carbon nanotubes by applying a nanometer (nm) -sized metal powder at; Melting the metal powder coated on the carbon nanotube thin film by high temperature heat treatment or plasma post-treatment in an ammonia gas, hydrogen gas and inert gas atmosphere; And forming a carbon electron emission layer on the carbon nanotube thin film by adhering the metal substrate to the carbon nanotube through the molten metal powder.

Instead of the carbon nanotube thin film, the carbon electron emission layer is mixed with powders such as metals, alloys, and metal compounds on a metal substrate to form various materials such as wires, bars, and plates. The carbon electron emission layer may be formed by mixing carbon nanotubes on a substrate such as a metal, a semiconductor wafer, quartz, and ceramic, instead of a thin film of carbon nanotubes. The carbon electron emission layer may be formed by mixing carbon nanotubes on a porous substrate such as AAO (anodic aluminum oxide), zeolite, and silica instead of a thin film of carbon nanotubes.

The metal powder is a metal of Ag or Au, a metal compound of Cu-Ag or Cu-Ti, the melting point of the metal powder is 300 ~ 1,100 ℃, the metal powder is a metal, alloy having a melting point of about 300 ~ 1,100 ℃ Of course, any of the metal compounds can be used.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a schematic diagram of the RTCVD used for the growth of carbon nanotubes according to the present invention, Figure 3 is a process chart for the growth of carbon nanotubes of Figure 2, Figure 4 is a formation of a carbon nanotube electron emission layer according to the present invention It is a figure showing a process.

In the figure, 10 is a quartz chamber, 12 is a halogen lamp, 14 is a gas inlet, 16 is a gas outlet, 18 is a thermocouple, 20 is a substrate holder, 30 is a carbon nanotube (CNT), 40 Silver metal powder (for example, metal Ag or Au and Cu-Ag or Cu-Ti powder which is a metal compound), 50 is plasma, 60, 70 is a metal melt layer, 80 is a hybrid melt layer, respectively.

Figure 2 is a schematic diagram of rapid thermal CVD (RTCVD) used for carbon nanotube growth, the gas was used C ₂ H ₂ and Ar. The chamber 10 was pumped with a rotary pump and the pressure was measured using a baratron gauge. During the growth of the carbon nanotubes 30, the pressure was maintained through a check valve installed at the end of the chamber 10. After first maintaining the inside of the chamber 10 in a vacuum, the substrate 20 is heated by a halogen lamp 12. The temperature of the reaction chamber 10 is raised to a constant rate up to 650 ° C. (X in Fig. 3) When the target temperature is reached, it is maintained for several minutes (X in Fig. 3), and then C ₂ through the gas inlet 14 Inflow of H ₂ and Ar gas (Fig. 3 (iii)) A process diagram for this process is shown in FIG. At this time, the temperature observation is made by the thermocouple 18, the flow rate of C ₂ H ₂ and Ar gas is controlled by a mass flow controller (MFC).

The carbon nanotubes 30 may be grown by the generalized RTCVD method as described above, and in the present invention, the carbon nanotubes 30 grown using the same apparatus are mounted on the substrate 20, and then the electrons are processed in the following process. An emission source was produced.

The composition of the carbon electron emission layer of the carbon nanotube electron emission source of the present invention is a mixture of a metal and a metal compound having a nanometer (nm) size and the like and the carbon nanotube 30, and then hydrogen gas, ammonia It is configured to maintain at 300 ~ 1,100 ℃ the melting point of the metal in the gas and inert gas atmosphere.

Meanwhile, the carbon electron emission layer may be formed on the substrate 20 such as semiconductor wafer, quartz and ceramic, and the metal substrate 20 such as SUS instead of the thin film of carbon nanotube 30. Of course, it can be made by mixing the nanotubes (30).

(First embodiment)

A thin film of carbon nanotubes 30 is grown on a metal substrate 20 by a rapid thermal CVD (RTCVD) method of FIG. 2, which is a conventional method for synthesizing carbon nanotubes 30 (see FIG. 4A).

Next, a metal powder 40 (for example, Cu—Ag metal compound) is thinly coated on the thin film of carbon nanotubes 30 (see FIG. 4B).

As shown in FIG. 4B, the carbon nanotube 30 thin film coated with a thin metal powder 40 is maintained at about 950 ° C. for 15 minutes at several tens of torr in an ammonia gas, hydrogen gas, and argon gas atmosphere with RTCVD equipment. As a result, the metal powder 40 is melted (see FIG. 4C).

This is a process for enclosing the tip of the carbon nanotubes 30 with metal, and may be maintained at 900 ° C. lower than 950 ° C. for about 15 minutes at several tens of Torr in an ammonia gas and argon gas atmosphere.

In addition, as shown in FIG. 4B, the carbon nanotube 30 thinly coated with the metal powder 40 is subjected to plasma post-treatment in an ammonia gas, hydrogen gas, and argon gas atmosphere with a plasma CVD apparatus. Melt (see FIG. 4D).

Second Embodiment

One of the conventional methods for synthesizing the carbon nanotubes 30 is plasma CVD (PECVD, dc-PECVD, hf-PECVD, rf-PECVD, MPECVD, etc.) on the metal substrate 20 of the carbon nano A thin film of tube 30 is grown (see FIG. 4A).

Next, the metal powder 40 (Cu-Ag metal compound) is thinly applied to the thin film of carbon nanotubes 30 (see FIG. 4B).

As shown in FIG. 4B, the carbon nanotube 30 thin film coated with a thin metal powder 40 is maintained at about 950 ° C. for 15 minutes at several tens of torr in an ammonia gas, hydrogen gas, and argon gas atmosphere with RTCVD equipment. As a result, the metal powder 40 is melted (see FIG. 4C).

In addition, as shown in FIG. 4B, the carbon nanotube 30 thinly coated with the metal powder 40 is plasma-treated with a plasma CVD apparatus in ammonia gas, hydrogen gas, and argon gas atmosphere, thereby performing the metal powder 40. Melt (see FIG. 4D).

As shown in the first and second embodiments, the molten state of the carbon nanotubes 30 and the metal 40 after the components of FIG. 4B are subjected to high temperature heat treatment or plasma post-treatment in a gas atmosphere is shown in FIGS. 5A and 5B. Shown.

5A illustrates that a metal molten layer 60 forming a carbon electron emission layer between a substrate 20 and a carbon nanotube 30 is formed in a plate shape to form a space between the substrate 20 and the carbon nanotube 30. It can be expected to improve the adhesion, Figure 5b can be expected to reduce the oxidative degradation of the carbon nanotubes 30 in the form of the metal melt layer 70 forming the carbon electron emission layer surrounds the carbon nanotubes (30).

(Third Embodiment)

The carbon nanotubes 30 are mixed on the metal substrate 20 or the silicon substrate 20 together with the nanometer (nm) -sized metal powder (for example, metal Ag and Cu-Ag powder, which is a metal compound). Prepare (see Figure 6).

After mixing the carbon nanotube 30 and the metal powder 40 on the substrate 20, the process shown in Figures 4c and 4d is carried out to 300 ~ 950 ℃ at tens Torr of ammonia gas and argon gas atmosphere Hold to melt the metal powder 40.

As shown in the third embodiment, the molten state of the carbon nanotubes 30 and the metal 40 after the components of FIG. 6 are subjected to high temperature heat treatment or plasma post-treatment in a gas atmosphere is shown in FIG. 7.

FIG. 5A illustrates that a hybrid molten layer 80 forming a carbon electron emission layer between a substrate 20 and a carbon nanotube 30 is formed in various forms such as a wire, a bar, and a plate. Thus, the adhesion between the substrate 20 and the carbon nanotubes 30 can be expected to be improved.

(Example 4)

Substrates such as semiconductor wafers, quartz and ceramics together with nanometer (nm) -sized metal powders (40: metal Ag or Au and metal compounds Cu-Ag or Cu-Ti powders) 20); Metal substrate 20 such as SUS; Alternatively, the carbon nanotubes 30 may be prepared by mixing them on the porous substrate 20 such as AAO (anodic aluminum oxide), zeolite, and silica. And it melt | maintains at 300-700 degreeC in tens of Torr in hydrogen gas, ammonia gas, and inert gas atmosphere.

8 is a scanning electron microscopy (SEM) photograph of a carbon nanotube thin film synthesized by a rapid thermal CVD (RTCVD) method, which is one of the conventional methods of the first embodiment of the present invention.

FIG. 9 is a scanning electron microscope (SEM) photograph of the carbon nanotube thin film of FIG. 8 heat-treated at 950 ° C. FIG. In FIG. 9, the carbon nanotube 30 thin film heat-treated at a high temperature of 950 ° C. is changed into a circular mesh shape, and each carbon nanotube 30 maintains the shape of a tube. As can be seen from b1 of FIG. 9 and b2 of FIG. 9, it can be seen that the carbon nanotubes 30 at the b2 point are cleaner than the b1 point.

10 is a scanning electron microscopy (SEM) photograph of a thin film of carbon nanotubes 30 heat-treated at 900 ° C. of the first embodiment of the present invention, and shows that each carbon nanotube 30 tip is covered with a metal.

FIG. 11 is a scanning electron microscopy (SEM) photograph of the carbon nanotube thin film of the second embodiment of the present invention, and shows the end of the carbon nanotube 30 grown vertically by the plasma CVD method.

FIG. 12 is a scanning electron microscope (SEM) photograph of the heat-treated carbon nanotube thin film of FIG. 11 at 950 ° C. FIG. The end portion of the carbon nanotubes 30 converges to arbitrary reference points to show that the conical bundle is made. The distance between the vertices of the conical bundles is thus expected to be greater than the spacing between the tube tips in FIG. 11 to reduce the screen effect that interferes with the field emission characteristics.

In conclusion, the present invention uses a rapid thermal chemical vapor deposition (RTCVD) or plasma CVD method to grow the carbon nanotubes 30, and grows the carbon nanotubes 30 on the metal substrate 20 to form the emitter. It was prepared to be used as a source. The post-treatment was performed for application as an emitter capable of stably discharging the carbon nanotubes 30 directly grown on the substrate 20, and the density of the carbon nanotubes 30 was adjusted by adjusting the size of the catalyst metal. Was intended. Therefore, the density of the carbon nanotubes 30 and the bonding state with the substrate 20 were observed by SEM and the like, and the cleanness of the carbon nanotubes 30 due to post-treatment was also observed. 3 kW could be applied to the cathode portion having the 0.5 mm gap of the carbon nanotubes 30 grown on the substrate 4 mm 2, and a current of 4.5 kW could be stably obtained from the anode portion.

As described above, according to the method for producing a carbon nanotube electron emission source using the metal compound according to the present invention, for the application as a stable carbon nanotube electron emission source capable of emitting a very large current, It can melt and adhere the media such as metals, alloys and metal compounds for strong adhesion between the tube and the substrate and at the same time expand the post-treatment conditions such as plasma and high temperature heat treatment. Compound composition of and can prepare electron emitting layer of carbon nanotubes of various geometric shapes such as wire, bar, and plate, and is convenient for constructing carbon nanotube electron emission source. This has the effect of extending performance and its applicability.

What has been described above is only one embodiment for carrying out the method for producing a carbon nanotube electron emission source using the metal compound according to the present invention, the present invention is not limited to the above-described embodiment, the technical idea of the present invention Of course, it can be implemented in various forms by those skilled in the art.

Claims (8)

Forming a carbon nanotube thin film on a metal substrate by plasma CVD or RTCVD; Applying a metal powder of micrometer (nm) to nanometer (nm) size on the carbon nanotube thin film; Melting the metal powder coated on the carbon nanotube thin film by high temperature heat treatment or plasma post-treatment in an ammonia gas, hydrogen gas and inert gas atmosphere; And Forming a carbon electron emission layer on the carbon nanotube thin film by adhering the metal substrate to the carbon nanotube through the melt of the metal powder. Method for producing a carbon nanotube electron emission source using a metal compound comprising a. The method of claim 1, Instead of the carbon nanotube thin film, the carbon electron emission layer is mixed with powders such as metals, alloys, and metal compounds on a metal substrate to form various materials such as wires, bars, and plates. Method for producing a carbon nanotube electron emission source using a metal compound, characterized in that the form. The method of claim 1, Instead of the carbon nanotube thin film, the carbon electron emission layer is formed by mixing carbon nanotubes on a substrate such as a metal, a semiconductor wafer, quartz, and ceramic. Method for producing a nanotube electron emission source. The method of claim 1, Carbon nanotube electrons using a metal compound, characterized in that the carbon electron emission layer is made by mixing carbon nanotubes on a porous substrate such as AAO (anodic aluminum oxide), zeolite and silica instead of a thin film of carbon nanotubes. Method of producing an emission source. The method of claim 1, The metal powder is a method of producing a carbon nanotube electron emission source using a metal compound, characterized in that the Ag or Au. The method of claim 1, The metal powder is a method of producing a carbon nanotube electron emission source using a metal compound, characterized in that the metal compound of Cu-Ag or Cu-Ti. The method according to claim 1, 5 or 6, Melting point of the metal powder is a method of producing a carbon nanotube electron emission source using a metal compound, characterized in that 300 ~ 1,100 ℃. The method of claim 7, wherein The metal powder is a method of producing a carbon nanotube electron emission source using a metal compound, characterized in that the metal, alloy and metal compound having a melting point of about 300 ~ 1,100 ℃.

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