JP2007210853A - Method for producing carbon nanotube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To grow carbon nanotubes having specific chirality by using catalyst particulates. <P>SOLUTION: The carbon nanotubes are grown by a CVD method where bowl-shaped fullerenes are used as a raw material gas and where the catalyst particulates whose diameter is controlled to be ±0.05 nm are used as a catalyst. The carbon nanotubes having specific chirality specified by the diameter of the catalyst particulates and the structure of the bowl-shaped fullerenes are grown. The supply of the bowl-shaped fullerenes is made enough where carbon concentration in the catalyst particulates is saturated. A normal raw material gas can be used when the carbon nanotubes are grown. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a carbon nanotube production method for growing carbon nanotubes on catalyst fine particles, and more particularly to a carbon nanotube production method for selectively growing carbon nanotubes having a specified chirality.

  Since carbon nanotubes have unique physical and chemical properties derived from their structure, they are expected to be applied in many fields such as electronics and chemistry. For example, FETs using carbon nanotubes as channels, electronic devices using carbon nanotubes as electron-emitting electrodes, or substance sensors using carbon nanotubes are being developed.

  The physical and chemical properties of such carbon nanotubes vary greatly depending on the skeleton structure of the carbon nanotubes, that is, the chirality. For this reason, in order to apply carbon nanotubes to these applications, it is necessary to use chiral carbon nanotubes having specific properties.

  FIG. 8 is a diagram showing the chirality dependency of the band gap, and shows the change in the band gap due to the difference in the chirality of the carbon nanotubes. FIG. 9 is a partially enlarged view showing the chirality dependency of the band gap, and a part of FIG. 8 is enlarged.

  Referring to FIG. 8, the carbon nanotubes are divided into a group of semiconductivity in which the diameter of the carbon nanotube increases and the band gap becomes small, and a group of semiconductors in which the band gap is zero, that is, a group of metals. Further, referring to FIG. 9, even if the carbon nanotube has a diameter in a range of ± 0.05 nm, a plurality of metallic carbon nanotubes having a zero band gap and a plurality of semiconducting carbons having a band gap are used. Nanotubes exist.

  These carbon nanotubes have different chiralities, and not only the characteristics change from semiconductor to metallic due to the difference in chirality, but also the band gap, which is an important characteristic as a semiconductor, differs depending on the chirality. Therefore, it is important to control the chirality of carbon nanotubes for electronics applications. In addition, since the chemical properties are also defined by chirality, it is important to control the chirality as well.

  In the production of carbon nanotubes having a specific chirality, a conventional method has been generally used in which carbon nanotubes with various chiralities are mixed, and the produced carbon nanotubes are chemically treated to separate carbon nanotubes with a specific chirality. It has been. For example, a semiconductor and metallic carbon nanotubes are separated by chemical treatment, or carbon nanotubes having a specific chirality are separated by chemical treatment.

  However, the methods for separating carbon nanotubes having a specific chirality by these chemical treatments not only have a low yield, but also cause damage to the carbon nanotubes accompanying the chemical treatment.

  On the other hand, a method using catalyst fine particles is known as a method for producing carbon nanotubes that has a high yield and can avoid damage caused by chemical treatment. In this method, a raw material gas such as methane or alcohol is supplied to catalyst fine particles, and carbon nanotubes are grown on the catalyst fine particles. The diameter of the carbon nanotubes grown on the catalyst fine particles is determined by the diameter of the catalyst fine particles. If the diameter of the carbon nanotube is determined, the chirality is usually determined. Therefore, the chirality of the produced carbon nanotube can be controlled by controlling the diameter of the catalyst fine particles.

  Conventionally, catalyst fine particles having a predetermined diameter have been formed by forming a catalyst thin film on a substrate and then aggregating it by heating.

  However, referring to FIG. 9, in order to control the chirality by the diameter of the catalyst fine particles, the diameter of the catalyst particles is controlled within a range where carbon nanotubes having different chiralities do not grow, for example, a range of 1.0 nm ± 0.02 nm. There is a need to. In the conventional method of heating and aggregating the above-described catalyst thin film, it is difficult to precisely control the diameter, and it is very difficult to manufacture carbon nanotubes by controlling chirality.

  Furthermore, there may be carbon nanotubes having very close diameters (for example, within ± 0.02 nm) or almost the same diameter but different in chirality. At this time, even if the diameter of the catalyst fine particles can be controlled within the range of ± 0.02 nm, the chirality of the carbon nanotube cannot be controlled by this alone.

A method of controlling the chirality of carbon nanotubes by controlling the shape of the catalyst has been devised. (See, for example, Patent Document 1)
In this method, a bar in which a catalyst metal is embedded in an Ag bar is repeatedly stretched and sliced to produce a substrate in which a small catalyst metal is embedded in an Ag plate. The catalyst metal that appears on the surface of the Ag plate is formed in a concentric circle shape, a spiral shape, or a dot shape. The carbon nanotubes grown on the substrate grow with the diameter and the layer structure controlled by the shape of the catalyst. Therefore, it is possible to produce carbon nanotubes having a controlled diameter and cross-sectional layer structure.
JP 2005-238142 A

  As described above, the conventional method of controlling the chirality of the carbon nanotubes by controlling the diameter of the catalyst fine particles has a problem that it is difficult to control the diameter of the catalyst fine particles as precisely as required for the chirality control. . Even if the diameter of the carbon nanotubes can be controlled, there may be carbon nanotubes having almost the same diameter but different chirality. In this case, it is difficult to control the chirality.

  In the conventional method of controlling the diameter and cross-sectional layer structure of the carbon nanotubes by the shape of the catalyst metal, the catalyst metal is formed by special metal processing, so that the manufacturing process is complicated and long. Even if the diameter and the cross-sectional layer structure can be controlled, it is difficult to control the chirality.

  An object of the present invention is to provide a carbon nanotube production method capable of growing carbon nanotubes with controlled chirality.

  In order to solve the above-described problems, a method for producing carbon nanotubes according to the present invention includes a step of supplying catalyst fine particles controlled to a predetermined diameter, and a catalyst fine particle having a saturated carbon concentration. And supplying a fullerene.

  That is, in the present invention, soot-like fullerene is supplied when the catalyst fine particles controlled to have a predetermined diameter reach the saturated carbon concentration. Thereafter, carbon nanotubes are grown on the catalyst fine particles having reached the saturated carbon concentration.

  The inventor of the present invention has clarified through experiments that carbon nanotubes having a specific chirality are grown by supplying soot-like fullerene to catalyst fine particles having reached the saturated carbon concentration and then growing the carbon nanotubes. The diameter of the carbon nanotube was defined by the diameter of the catalyst fine particles, and the chirality was defined by the skeleton of cage-like fullerene. This experimental result shows that the chirality of the carbon nanotube is determined by the diameter of the catalyst fine particles and the type of the cage fullerene.

  The present invention has been devised on the basis of such experimental facts. The chirality of carbon nanotubes grown by supplying cage-like fullerene when catalyst fine particles of a predetermined diameter are used as a catalyst and when the carbon concentration of the catalyst fine particles is saturated. Control.

  The mechanism by which the chirality of carbon nanotubes grown by the type of cage-like fullerene supplied in the growth process is controlled has not been fully elucidated. When the inventors of the present invention attach soot-like fullerene to the surface of the catalyst fine particles in a saturated carbon concentration state, the soot-like fullerene is adsorbed in a state where the skeleton is held on the surface of the catalyst fine particles and matches the skeleton. Only carbon nanotubes with chirality are considered to grow. Therefore, the chirality of the grown carbon nanotube is defined by the skeleton of the cage-like fullerene, and the diameter of the carbon nanotube is defined by the diameter of the catalyst fine particle as is well known. As a result, it is considered that carbon nanotubes having a diameter determined by the diameter of the catalyst fine particles and a chirality determined by the structure of the cage-like fullerene are selectively grown. Note that the diameter of the grown carbon nanotubes may vary depending on the substrate and growth conditions, and does not necessarily match the diameter of the catalyst fine particles. For this reason, it is desirable to experimentally determine the diameter of the catalyst fine particles so that the desired carbon nanotubes grow.

  As described above, the chirality of the growing carbon nanotube can be controlled by the diameter of the catalyst fine particles and the type of cage-like fullerene. At this time, even if the kind of cage-like fullerene is determined, carbon nanotubes having a plurality of chiralities grow if the diameter distribution of the catalyst fine particles is large. In order to control the chirality of the carbon nanotubes grown when one kind of soot-like fullerene is supplied, it is desirable to adjust the diameter distribution of the catalyst fine particles within a range of ± 0.05 nm.

  In the present invention described above, it is sufficient that the soot-like fullerene is supplied when the carbon concentration of the catalyst fine particles is saturated. Therefore, when the carbon concentration of the catalyst fine particles is less than the saturation concentration, the raw material gas used for normal carbon nanotube growth, such as chain hydrocarbons or various alcohols, is used in order to increase the carbon concentration of the catalyst fine particles. It can be supplied as a source gas. These normal source gases are much cheaper than soot-like fullerenes, which can reduce manufacturing costs. Of course, instead of these normal source gases, soot-like fullerene may be supplied before the catalyst fine particles reach the saturated carbon concentration. Further, the catalyst-like fullerene may be supplied immediately without supplying the catalyst fine particles having a saturated carbon concentration from the beginning and without supplying the first raw material gas.

  Furthermore, after supplying cage-like fullerene to catalyst fine particles having a saturated carbon concentration, when supplying a second source gas to grow carbon nanotubes, an inexpensive source gas used for normal carbon nanotube growth is used. It can supply as 2nd source gas. This second source gas may be the same as the first source gas described above. In addition, cocoon-like fullerene may be supplied instead of the second source gas.

  The catalyst fine particles having a predetermined diameter used in the present invention are, for example, vaporized by irradiating a catalyst metal target with a laser beam, solidified to form fine particles, and then a differential electrostatic classifier (DMA: differential). It can classify and manufacture using Mobility Analyzer. The cocoon-like fullerene can also be produced by chemically purifying fullerene produced by the FVP method (flash vacuum pyrolysis method) or by a known chemical synthesis method for a specific type. .

  According to the present invention, carbon nanotubes having a chirality determined based on the diameter of catalyst fine particles and the type of cage-like fullerene can be easily produced without subjecting the catalyst to processing.

  1st Embodiment of this invention is related with the method of manufacturing the carbon nanotube which has a chiral index (10,0) on Si substrate using Ni catalyst fine particles.

  FIG. 1 is a configuration diagram of a carbon nanotube production apparatus according to a first embodiment of the present invention, and shows an outline of the carbon nanotube production apparatus.

  Referring to FIG. 1, in the first embodiment, a target 9 made of a catalytic metal, for example, Ni is placed in a vacuum vessel (not shown), and the surface is irradiated with laser light 8a emitted from an Ar laser 8. Then, the surface of the target 9 is evaporated, and the vapor is cooled with a He carrier gas and solidified to form catalyst fine particles 3 made of Ni.

  The catalyst fine particles 3 ride on the flow of the carrier gas (for example, He), are annealed while passing through the furnace core tube 7a of the annealing furnace 7, and then introduced into the differential electrostatic classifier 11. The catalyst fine particles 3 are classified while passing through the differential electrostatic classifier 11, and the catalyst fine particles 3 having a classified diameter of 0.78 nm ± 0.05 nm are introduced into the growth furnace 1 from the nozzle 11a.

  The growth furnace 1 is provided with a gas introduction port 1a at the front end and an exhaust port 1b at the rear end. A switching valve 1c is provided at the tip of the gas introduction port 1a, and the gas supplied into the growth furnace 1 is switched to the raw material gas 4 made of methane or the bowl-shaped fullerene 5 using Ar as a carrier gas. Can do. The soot-like fullerene 5 supplied to the growth furnace 1 is supplied by heating and sublimating the solid soot-like fullerene stored in the evaporator 5 a and mixing it with the Ar carrier gas 6.

FIG. 2 is a diagram showing the structure of the bowl-shaped fullerene used in the first embodiment of the present invention, and shows the carbon bond forming the fullerene skeleton structure. In the first embodiment, C ₄₀ cage-like fullerene 5 having the skeleton shown in FIG. 2 was used.

  The catalyst fine particles 3 introduced into the growth furnace 1 from the nozzles 11 a are dispersed and adsorbed on the upper surface of the Si substrate 2 disposed horizontally in the growth furnace 1. The substrate 2 is heated in advance to a growth temperature, for example, 800 ° C.

  In the first embodiment, during the growth of the carbon nanotube, the switching valve 1c is fixed in the inflow direction of the saddle-like fullerene 5, and the saddle-like fullerene 5 is continuously supplied into the growth furnace 1 from the start of growth to the end of growth. did. That is, the cage-like fullerene 5 is used as a raw material gas used for growing carbon nanotubes. In this step, carbon nanotubes grew on the catalyst fine particles 3.

  The grown carbon nanotubes were observed using an absorption spectrum, a fluorescence spectrum, and a transmission electron microscope (TEM) image. In the transmission electron microscope image, SWNTs (single-walled nanotubes) having a diameter approximately equal to the diameter of carbon nanotubes having a chiral index (10, 0) of 0.78 nm were observed. In the absorption spectrum, a sharp peak corresponding to the carbon nanotube having a chiral index (10, 0) was observed, and a peak corresponding to the metal nanotube was not observed. In addition, in the fluorescence spectrum, only strong fluorescence corresponding to carbon nanotubes having a chiral index (10, 0) was observed. The observation results of the absorption spectrum and the fluorescence spectrum confirm the observation result by the transmission electron microscope image, and strongly suggest that the carbon nanotube having the chiral index (10, 0) has grown.

  FIG. 3 is a diagram showing the chirality of a carbon nanotube having a diameter close to that of the first embodiment, and shows the chirality of a carbon nanotube having a diameter close to the diameter of the carbon nanotube having a chiral index (10, 0).

  Referring to FIG. 3, the chirality of the carbon nanotubes having a diameter within the range of 0.78 nm ± 0.05 nm of the catalyst fine particles 3 used in the first embodiment is metallic (7, 4 ), (6, 6) and (10, 1), and there are seven types of semiconductors (6, 5) to (8, 4). Nevertheless, in the first embodiment, only carbon nanotubes having a single chiral index (10, 0) are produced practically.

  The second embodiment of the present invention relates to a growth method in which the supply of soot-like fullerene is limited to a short period before and after the catalyst fine particles reach the saturated carbon concentration.

  Referring to FIG. 1, in the second embodiment, similarly to the first embodiment, Ni catalyst fine particles are first adsorbed on the Si substrate 2 disposed in the growth reactor 1.

  Next, the switching valve 1 c is switched to the inflow direction of the raw material gas 4, and methane is supplied as the first raw material gas 4 into the growth reactor 1 for 10 seconds. In this step, the catalyst fine particles 3 absorb the carbon of the raw material gas and the carbon concentration increases. The supply of methane is terminated before the catalyst fine particles 3 reach the saturated carbon concentration.

  Next, the switching valve 1c is switched to the inflow direction of the saddle-like fullerene 5, and the saddle-like fullerene 5 is supplied into the growth furnace 1 together with the Ar carrier gas 6 for 10 seconds. In this step, the carbon concentration of the unsaturated catalyst fine particles 3 reaches the saturated carbon concentration. Thereafter, carbon nanotubes begin to grow from the surface of the catalyst fine particles 3 having a saturated carbon concentration. The supply of the soot-like fullerene 5 is performed at least until the carbon concentration of the catalyst fine particles 5 is saturated and the skeleton of the soot-like fullerene 5 is formed on the surface thereof.

  Next, the switching valve 1 c is switched to the inflow direction of the source gas 4, and methane is supplied into the growth reactor 1 as the second source gas 4. In this step, carbon nanotubes having a chiral index (10, 0) are grown on the catalyst fine particles 5. The supply of the second source gas is performed until the carbon nanotube grows to a desired length, and the supply is stopped at that time.

  The carbon nanotubes produced according to the second embodiment were not found to be different from the carbon nanotubes produced according to the first embodiment in absorption spectrum analysis, fluorescence spectrum analysis, and transmission electron microscope image observation. In the second embodiment, the supply period of the expensive bowl-shaped fullerene 5 is limited to a short period before and after the catalyst fine particles 3 reach the saturated carbon concentration, so that the manufacturing cost can be reduced.

  As the first and second source gases in the second embodiment, source gases used in normal carbon nanotube growth, such as chain hydrocarbons or alcohols, can be used.

The third embodiment of the present invention relates to a manufacturing method in which carbon nanotubes are formed on a SiO ₂ substrate having a Ti base thin film formed on the upper surface using Co catalyst fine particles.

  FIG. 4 is a cross-sectional view of catalyst fine particles according to a third embodiment of the present invention, showing the shape of the catalyst fine particles before and after being adsorbed on the substrate.

Referring to FIG. 4, in the third embodiment, first, a Ti underlayer 22 having a thickness of, for example, 1 nm is formed on a SiO ₂ substrate 21 by sputtering. This Ti underlayer 22 is provided in order to improve the catalytic activity of the catalytic metal. Next, in the same manner as in the first embodiment, the Co catalyst fine particles 24 are supplied into the growth furnace 1 and adsorbed onto the substrate 21.

Next, in the same process as in the first or second embodiment, the cage-like fullerene 5 was supplied into the growth furnace 1, and carbon nanotubes were grown on the Co catalyst fine particles 23 adsorbed on the substrate 1. However, the cage-like fullerene 5 was selected according to the chirality of the desired carbon nanotube. As a result, carbon nanotubes having a diameter larger than the diameter of the Co catalyst fine particles 24 grew. When this carbon nanotube was observed by absorption spectrum analysis, fluorescence spectrum analysis, and transmission electron microscope image observation, it was SWNT and was a carbon nanotube having one kind of chirality. The diameter of the Co catalyst fine particles 24 was measured with a transmission electron microscope by adsorbing the Co catalyst fine particles 24 at room temperature on the SiO ₂ substrate 21 on which the Ti underlayer film 22 was not formed.

  In the third embodiment, the diameters of the catalyst fine particles 24 and the growing carbon nanotubes are different. For this reason, it is necessary to investigate in advance the relationship between the diameter of the carbon nanotubes grown by experiment and the diameter of the catalyst fine particles 24.

The fourth embodiment of the present invention relates to a manufacturing method in which carbon nanotubes are formed on a SiO ₂ substrate using Co—Ti catalyst fine particles. That is, the Ti undercoat film 22 of the third embodiment is not formed, and Co—Ti catalyst fine particles are used instead of the Co catalyst fine particles.

  FIG. 5 is a cross-sectional view of catalyst fine particles according to a fourth embodiment of the present invention, showing the shape of catalyst fine particles before and after being adsorbed on a substrate.

In the fourth embodiment, first, referring to FIG. 1 and FIG. 5, catalyst fine particles 3 (catalyst fine particles 26 in FIG. 5) made of a Co—Ti alloy are produced using a targate 9 made of a Co—Ti alloy. Then, as in the first embodiment, this was classified and introduced into the growth furnace 1 and adsorbed onto the SiO ₂ substrate 21. The catalyst fine particles 26 are made of a Co—Ti alloy, and the center of the diameter distribution is the same as the desired carbon nanotube diameter. Others are the same as the catalyst fine particles 24 of the third embodiment including the diameter distribution.

  Next, carbon nanotubes were grown on the catalyst fine particles 25 adsorbed on the substrate 21 by the same method as in the third embodiment. This carbon nanotube was a carbon nanotube having the same diameter as the catalyst fine particles 3 and comprising one kind of chirality.

  Thus, according to the fourth embodiment, carbon nanotubes having the same diameter as the catalyst fine particles 26 can be selectively produced.

  In order to clarify the reason why the diameter of the catalyst fine particles is different from the diameter of the growing carbon nanotube in the third embodiment described above, the inventors of the present invention conducted the following experiment.

Referring to FIGS. 4 and 5, carbon nanotubes are grown by adsorbing Co catalyst fine particles 24 on SiO ₂ substrate 21 having Ti underlayer 22. On the other hand, the Co—Ti catalyst fine particles 26 are adsorbed on the SiO ₂ substrate 21 (that is, SiO ₂ is exposed on the surface of the substrate 21) on which the Ti underlayer 22 is not provided to grow carbon nanotubes. The diameters of the catalyst fine particles 24 and 26 and the grown carbon nanotubes were compared. Note that the growth of any carbon nanotube uses methane as a source gas.

FIG. 6 is a diagram showing the diameter distribution of the catalyst fine particles and the carbon nanotubes. In FIG. The diameter distribution of the carbon nanotubes grown on the surface and the curve C represent the diameter distribution of the carbon nanotubes grown on the Co—Ti catalyst fine particles 25 adsorbed on the SiO ₂ substrate 21.

  Referring to FIG. 6, both Co catalyst fine particles 24 and Co—Ti catalyst fine particles 26 have the same diameter distribution and center diameter.

  Referring to the curve C, when the Co—Ti catalyst fine particles 26 are used, the diameters of the carbon nanotubes grown are distributed almost in the same manner as the diameter distribution of the catalyst fine particles 24 and 26. This indicates that carbon nanotubes having substantially the same diameter as the catalyst fine particles 26 have grown. On the other hand, referring to curve B, when the Co catalyst fine particles 24 are used, the diameter distribution of the carbon nanotubes is shifted in a larger direction. The carbon nanotubes corresponding to the curves (b) and (c) include those having other types of chirality.

The inventor of the present invention, referring to FIG. 4, the Co catalyst fine particles 23 adsorbed on the Ti underlayer 22 spread flatly because the wettability with the underlayer 22 is good, and the apparent diameter increases. It is considered that the diameter of carbon nanotubes grown using this as a catalyst also increases. On the other hand, referring to FIG. 5, even if the catalyst fine particles 25 containing Co as the main component are adsorbed on the SiO ₂ substrate 25 without the base film, the wettability with the SiO ₂ substrate 21 is poor and the particles aggregate into a spherical shape. The apparent diameter does not change before and after adsorption. For this reason, it is considered that the diameters of the carbon nanotubes and the catalyst fine particles 26 coincide.

  The Ti contained in the Ti underlayer 22 or the catalyst fine particles used in the third and fourth embodiments described above can grow carbon nanotubes without using them, but accelerates the growth of carbon nanotubes. Therefore, it is desirable to use these Ti. Further, instead of Ti, the catalyst fine particles generally contain a metal that increases the catalytic action, particularly a metal used as a base film, and the catalyst fine particles made of an alloy with these metals are directly adsorbed on the substrate surface. Thus, it is possible to make the diameter of the carbon nanotube that grows with the base film unnecessary and the wettability of the catalyst fine particle to the substrate close to the diameter of the catalyst fine particle.

  As the catalyst fine particles used in the present invention, a catalyst metal usually used for the growth of carbon nanotubes can be used, and for example, Fe, Co and Ni can be used.

  Further, the above-described cage-like fullerene used in the present invention is appropriately selected from various types of cage-like fullerenes known in accordance with the chiral index of the carbon nanotube to be grown.

  FIG. 7 is a diagram showing a skeleton structure of a cage-like fullerene, and shows carbons forming a fullerene skeleton and their bonds.

Referring to FIG. 7, known well-like fullerenes include, for example, C ₂₀ (corannulene), C ₃₆ , two types of C ₃₀ having different structures, or C ₃₀ . A cage-like fullerene selected from these can be used in the present invention.

As described above, the present invention disclosed in the following supplementary notes is disclosed in this specification.
(Additional remark 1) In the manufacturing method of the carbon nanotube which supplies a source gas to catalyst fine particles and grows a carbon nanotube on the said catalyst fine particle,
Supplying the catalyst fine particles controlled to a predetermined diameter;
And a step of supplying a cage fullerene having a predetermined skeletal structure to the catalyst fine particles having a saturated carbon concentration.
(Supplementary note 2) The method for producing carbon nanotubes according to supplementary note 1, wherein the catalyst fine particles are controlled within a range of ± 0.05 nm from a predetermined diameter.
(Supplementary Note 3) After the step of supplying the catalyst fine particles, supplying the first raw material gas to the catalyst fine particles to increase the carbon concentration of the catalyst fine particles;
The method for producing carbon nanotubes according to appendix 1 or 2, further comprising the step of supplying the soot-like fullerene to the catalyst fine particles to make the carbon concentration of the catalyst fine particles a saturated carbon concentration.
(Appendix 4)
After the step of supplying the soot-like fullerene to the catalyst fine particles having a saturated carbon concentration, the second raw material gas is supplied to the catalyst fine particles and is determined by the diameter of the catalyst fine particles and the skeleton structure of the soot-like fullerene 4. The method for producing carbon nanotubes according to appendix 1, 2, or 3, wherein carbon nanotubes having a chiral index are grown.
(Supplementary note 5) The method for producing a carbon nanotube according to supplementary note 4, wherein either one or both of the first and second source gases are made of a gas containing the bowl-shaped fullerene.
(Appendix 6) The method for producing carbon nanotubes according to appendix 1, 2, 3, 4 or 5, wherein the catalyst fine particles are fine particles made of a metal selected from Fe, Co and Ni, or an alloy thereof. .
(Appendix 7) The catalyst fine particles are made of an alloy containing a base material of the catalyst fine particles,
The method for producing carbon nanotubes according to appendix 1, 2, 3, 4, 5 or 6, wherein the substrate is made of a material having low wettability to the alloy containing the base material.

  By applying the present invention to the growth of carbon nanotubes of electronic elements, carbon nanotubes having stable characteristics can be produced, which greatly contributes to improvement of element characteristics.

Carbon nanotube production apparatus configuration diagram of the first embodiment of the present invention The figure showing the structure of the bowl-shaped fullerene used for 1st Embodiment of this invention The figure showing the chirality of the carbon nanotube which has a diameter close | similar to 1st Embodiment of this invention Cross-sectional view of catalyst fine particles according to third embodiment of the present invention Catalyst fine particle sectional view of a fourth embodiment of the present invention Diagram showing diameter distribution of catalyst fine particles and carbon nanotubes Diagram showing the skeleton structure of cage-like fullerene Diagram showing the dependence of the band gap on chirality Partial enlarged view showing chirality dependence of band gap

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Growth furnace 1a Gas inlet 1b Exhaust 1c Switching valve 2 Substrate 2
3, 23-26 catalyst fine particles 4 raw material gas 5 bowl-shaped fullerene 5a evaporator 6 carrier gas 7 annealing furnace 7a furnace core tube 8 laser 8
8a Laser beam 9 Target 11 Differential electrostatic classifier 11a Nozzle 21 SiO ₂ substrate b Diameter distribution of catalyst fine particles B, C Diameter distribution of carbon nanotubes

Claims (5)

In the method for producing carbon nanotubes, the raw material gas is supplied to the catalyst fine particles and the carbon nanotubes are grown on the catalyst fine particles.
Supplying the catalyst fine particles controlled to a predetermined diameter;
And a step of supplying fullerene having a predetermined skeletal structure to the catalyst fine particles having a saturated carbon concentration.   The method for producing carbon nanotubes according to claim 1, wherein the catalyst fine particles are controlled within a range of ± 0.05 nm from a predetermined diameter. After the step of supplying the catalyst fine particles, supplying the first raw material gas to the catalyst fine particles to increase the carbon concentration of the catalyst fine particles;
3. The method for producing carbon nanotubes according to claim 1, further comprising a step of supplying the fullerene to the catalyst fine particles to make a carbon concentration of the catalyst fine particles a saturated carbon concentration.   After the step of supplying the fullerene to the catalyst fine particles having a saturated carbon concentration, the second raw material gas is supplied to the catalyst fine particles and has a chiral index determined by the diameter of the catalyst fine particles and the skeleton structure of the fullerene. The carbon nanotube production method according to claim 1, 2, or 3, wherein the carbon nanotube is grown.   5. The method of manufacturing a carbon nanotube according to claim 4, wherein one or both of the first and second source gases are made of a gas containing the fullerene.

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