JP2002293523A - Carbon nanotube film, carbon nanotube film-containing SiC substrate, carbon nanotube film, and methods for producing them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon nanotube film orientated in a predetermined direction, a carbon nanotube film-containing SiC substrate and a carbon nanotube film, and a method for manufacturing these at a large area and at low cost. SOLUTION: The carbon nanotube film 3 is formed on a substrate 1.
A polycrystalline film 2 made of silicon carbide is formed thereon, and thereafter,
Substrate 1 on which silicon carbide polycrystalline film 2 is formed is immersed in a processing solution to separate silicon carbide polycrystalline film 2 from the substrate, and then silicon carbide polycrystalline film body 2a separated in a vacuum is decomposed by silicon carbide. By heating to a temperature at which silicon atoms are lost from the surface of the silicon carbide polycrystalline film, silicon atoms are removed from the silicon carbide, and a large number of carbon nanotubes are formed to grow from the surface of silicon carbide crystal base portion 2b to the inside. Consists of

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon nanotube film, a carbon nanotube film-containing SiC substrate, a carbon nanotube film, and a method for producing the same. More specifically, the present invention relates to a carbon nanotube film highly oriented in a predetermined direction, The present invention relates to a film-containing SiC substrate, a carbon nanotube film, and a method for producing the same.
The carbon nanotube film of the present invention, a carbon nanotube film-containing SiC substrate and a carbon nanotube film body,
Used for electron-emitting devices, gas separation membranes, magnetic materials, superconducting materials, electrode materials for secondary batteries, and the like.

[0002]

2. Description of the Related Art Methods for obtaining an alignment film of carbon nanotubes can be roughly divided into two methods.
One method is to coat a catalyst such as Fe, Co and Ni on a substrate to obtain a vertically oriented carbon nanotube alignment film by a CVD (Chemical Vapor Deposition) method, and the other is a silicon carbide single crystal. Is obtained by sublimating and decomposing a carbon nanotube alignment film extending perpendicular to the substrate (Japanese Patent Application No. 9-8751).
No. 8).

[0003] In addition, using a CVD, SOI (Silicon
A method has been proposed in which a silicon carbide single crystal is deposited on a substrate, the substrate is peeled off, and the silicon carbide single crystal is sublimated and decomposed to obtain a free-standing film of nanotubes (Japanese Patent Application No. 10-282214). No.).

[0004]

However, in the case of the CVD method using a catalyst, it is possible to obtain a carbon nanotube having a relatively large area, but the tube is easily bent and the metal used as the catalyst is a nanotube. Since it remains inside, there was a problem in the quality of the alignment film. On the other hand, the method of obtaining a carbon nanotube film by sublimating and decomposing a silicon carbide single crystal has a problem that the silicon carbide single crystal is expensive and its size is limited.

In a method of depositing a silicon carbide single crystal on an SOI substrate by a CVD method and sublimating and decomposing the silicon carbide single crystal, the thickness, crystallinity, etc., of a Si active layer of a commercially available SOI substrate are used to produce carbon nanotubes. A step of optimizing it was necessary, and was not suitable for mass production.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a carbon nanotube film oriented in a predetermined direction, a carbon nanotube film-containing SiC substrate and a carbon nanotube film, and a large-area and low-cost carbon nanotube film. It is intended to provide a method of manufacturing.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, in the carbon nanotube film according to claim 1, a polycrystalline film made of silicon carbide is formed on a substrate, and then the substrate on which the silicon carbide polycrystalline film is formed is immersed in a processing solution to form the silicon carbide polycrystalline film. Separating the crystal film from the substrate, and then heating the separated silicon carbide polycrystalline film in vacuum to a temperature at which silicon carbide is decomposed and silicon atoms are lost from the surface of the silicon carbide polycrystalline film. A plurality of carbon nanotubes formed by removing silicon atoms from silicon carbide and growing from the surface to the inside of the silicon carbide polycrystalline film.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a carbon nanotube film, comprising forming a polycrystalline film made of silicon carbide on a substrate, and then applying the substrate on which the silicon carbide polycrystalline film is formed to a treatment liquid. Immersion to separate the silicon carbide polycrystalline film from the substrate, and then decompose the silicon carbide polycrystalline film separated in a vacuum to cause silicon atoms to be lost from the surface of the silicon carbide polycrystalline film. By heating to a temperature, silicon atoms are removed from the silicon carbide to form a carbon nanotube film composed of a large number of carbon nanotubes grown and formed from the surface to the inside of the silicon carbide polycrystalline film. .

The material constituting the substrate on which the silicon carbide polycrystalline film is formed is not particularly limited as long as it does not easily react with silicon carbide when the silicon carbide polycrystalline film is formed. Further, the melting point of the material constituting the substrate is preferably 600 ° C. or more, more preferably 800 ° C. or more, provided that
The upper limit is usually 4000 ° C. If the melting point of the material constituting the substrate is too low, the substrate is deformed or melted during silicon carbide deposition, which is not preferable.

Further, the material forming the substrate preferably has a difference in thermal expansion coefficient from silicon carbide of less than 6 × 10 ⁻⁶ (/ ° C.). More preferably, it is less than 3 × 10 ⁻⁶ (/ ° C.). The difference in thermal expansion coefficient from silicon carbide may be zero. If this difference in thermal expansion coefficient is large, cracks may occur in the silicon carbide film when the substrate is etched. Examples of the material constituting the substrate include glass, Al, Ti, Cr, Gd, and G.
e, Hf, La, Mo, Nb, Pt, Rh, Ta, W,
V or an alloy containing these metal elements.
Of these, glass, Ti, Mo, and W are preferred.

The thickness of the substrate is not particularly limited, but is preferably not more than 500 μm, more preferably not more than 100 μm. This is because the smaller the thickness of the substrate, the smaller the residual stress on the silicon carbide polycrystalline film and the shorter the operation time in the etching step. On the other hand, if the thickness is too large, the residual stress on the silicon carbide polycrystalline film increases, and the film is cracked or the operation time in the step of separating the silicon carbide polycrystalline film from the substrate is undesirably long.

The silicon carbide polycrystalline film can be formed on a substrate by, for example, a vapor phase growth method, a liquid phase growth method, or the like. Of these, the vapor phase growth method is preferred.
VD method, MBE method, sputtering method, and the like.
VD and sputtering are preferred. When the silicon carbide polycrystalline film is manufactured by the CVD method, the film forming temperature is preferably as low as possible within a condition that does not impair the crystallinity of silicon carbide, and is usually from 250 to 800 ° C.

The surface of the silicon carbide polycrystalline film is in a state where the crystal faces are oriented in various directions. In order to obtain a carbon nanotube film oriented perpendicular to the substrate, when the silicon carbide is α-SiC, (00
In the case of β-SiC, it is preferably oriented in the (111) plane. When a silicon carbide polycrystalline film is manufactured by the above-mentioned vapor phase growth method, α
-SiC, the (0001) plane and β-SiC
In this case, the silicon carbide film can be easily formed so as to be oriented to the (111) plane.

The thickness of the silicon carbide polycrystalline film is proportional to the length of the carbon nanotube.
When manufacturing by the method D, the length of the carbon nanotube can be easily controlled by controlling the growth time.

The silicon carbide polycrystalline film formed on the substrate can be separated by corroding or dissolving the substrate by immersing it in a processing solution. The treatment liquid is not particularly limited as long as it does not damage the silicon carbide film, but an acid or alkali treatment liquid is preferable, and a corrosive liquid that easily corrodes the material of the substrate is particularly preferably used. When the substrate is glass, a hydrofluoric acid solution, an ammonium fluoride solution, or the like can be used as the etchant. However, a molten sodium oxide solution, a mixed solution of sodium carbonate and potassium nitrate and the like are not preferable because they damage the silicon carbide film.

In the present invention, the carbon nanotube film
Heats the separated silicon carbide polycrystalline film in vacuum
Then, Si was oxidized and evaporated as SiO, and remained.
C is manufactured by arranging it in a tubular tube structure.
It is. The carbon nanotube film is made of silicon carbide.
Vacuum degree as long as silicon atoms can be removed by decomposition
And the heating temperature can be obtained without particular limitation
You. Preferred vacuum is 10^-3-10^-9Torr (more good
Preferably 10^-Five-10 ^-9Torr). Also preferred
New heating temperature is 1200-2000 ° C (more preferable)
Is 1400 to 1800 ° C). Heating temperature is too high
And the formed carbon nanotubes mesh with each other
With this, some tubes absorb others and grow larger
Control the size of carbon nanotubes.
It becomes difficult. In addition, the degree of vacuum and heating temperature increase.
The rate at which silicon atoms are lost from SiC increases.
If the orientation of carbon nanotubes is likely to be disordered,
The diameter tends to be large, and carbon itself is also CO
And the carbon nanotubes become thinner,
Disappeared, forming a disordered graphite layer
It is not preferable. Heating the polycrystalline silicon carbide film
There are no particular limitations on the means for
Irradiation, direct current heating, infrared irradiation heating, microwave heating
Means such as heat and high frequency heating can be used.

According to a sixth aspect of the present invention, in the SiC substrate containing a carbon nanotube film, a polycrystalline film made of silicon carbide is formed on the substrate, and then the substrate on which the silicon carbide polycrystalline film is formed is immersed in a processing solution. The carbon nanotubes obtained by separating the silicon carbide polycrystal film from the substrate and heating the separated silicon carbide polycrystal film body in a vacuum to a temperature at which silicon atoms are lost. And a silicon carbide polycrystalline base located below the carbon nanotube film.

According to a tenth aspect of the present invention, in the method of manufacturing a carbon nanotube film-containing SiC substrate, a polycrystalline film made of silicon carbide is formed on the substrate, and then the substrate on which the silicon carbide polycrystalline film is formed is formed. The silicon carbide polycrystalline film is separated from the substrate by immersion in a treatment liquid, and the separated silicon carbide polycrystalline film body is heated in a vacuum to a temperature at which silicon atoms are lost. It is characterized by comprising the obtained carbon nanotube film, and a silicon carbide polycrystalline base located below the carbon nanotube film.

The carbon nanotube film-containing SiC substrate can be manufactured by the same method as described for the carbon nanotube film. In order to obtain a carbon nanotube film oriented perpendicular to the substrate, when the silicon carbide is α-SiC, (000
It is preferably oriented in the 1) plane. In the case of β-SiC, it is preferably oriented in the (111) plane. The present SiC substrate with a carbon nanotube film can have not only a silicon nanotube polycrystalline film having a carbon nanotube film on only one surface but also a carbon nanotube film on both the front surface and the back surface.

[0020] In the carbon nanotube film according to the eleventh aspect, a polycrystalline film made of silicon carbide is formed on a substrate,
Thereafter, the substrate on which the silicon carbide polycrystalline film is formed is immersed in a processing liquid to separate the silicon carbide polycrystalline film from the substrate, and then the silicon carbide polycrystalline film separated in vacuum is coated with silicon carbide. By heating to a temperature at which silicon atoms are lost from the surface of the polycrystalline silicon carbide film by decomposition, silicon atoms are completely removed from the silicon carbide, and the silicon carbide polycrystalline film is composed of a large number of carbon nanotubes.

Further, in the method of manufacturing a carbon nanotube film according to a fifteenth aspect, a polycrystalline film made of silicon carbide is formed on a substrate, and then the substrate on which the silicon carbide polycrystalline film is formed is treated with a processing solution. To separate the silicon carbide polycrystalline film from the substrate, and then decompose the silicon carbide polycrystalline film separated in a vacuum to cause silicon atoms to be lost from the surface of the silicon carbide polycrystalline film. By heating the film to a temperature at which the carbon atoms are removed, silicon atoms are completely removed from the silicon carbide to form a carbon nanotube film composed of only a large number of carbon nanotubes.

The carbon nanotube film of the present invention can be manufactured by the same method as described in the method of manufacturing the carbon nanotube film. Further, in order to obtain a carbon nanotube film oriented perpendicular to the film body, when the silicon carbide is α-SiC, it is preferable that the silicon carbide is oriented on the (0001) plane, and when the silicon carbide is β-SiC, (11
1) It is preferably oriented in the plane.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described with reference to examples.
This will be described specifically. Example 1 FIG. 1 shows a schematic view of the manufacturing method of Example 1. Substrate 1
A glass plate whose surface was mirror-polished was used. First, the microphone
Silicon carbide polycrystalline material having a thickness of 2
It was deposited to a thickness of 00 μm. Substrate ethanol,
Then, after ultrasonic cleaning with acetone and degreasing,
30 minutes in hydrogen plasma at 525 ° C in hydrogen plasma
For a while. The microwave output at this time was 400W.
Was. After the substrate temperature stabilizes, the source gas is introduced and the film is formed.
Started. CH as source gas for C_ThreeCl is the source of Si
SiH as feed gas_FourIt was used. The source gas is hydrogen
Supplied from a cylinder diluted and filled to 0%, and entered into the reaction chamber
Before mixing with hydrogen of the carrier gas. Each gas flow rate is H
_TwoIs 99sccm, SiH_FourIs 0.41 sccm, CH _Three
Cl was 0.51 sccm. Silicon carbide polycrystalline film 2
Was deposited by about 0.2 μm, and then the substrate was taken out. X-ray
According to the diffraction, the peak of β-SiC (111) is dominant.
Met. Also, in high-speed electron diffraction, the <111> orientation
Spots were confirmed. Therefore, the deposited film 2 has β
-It is thought that SiC is strongly oriented to <111>.
Was. After that, the substrate is NH_FourImmerse in F solution and dissolve substrate
(Etching) to separate the silicon carbide polycrystalline film.
Then, in a vacuum (1 × 10^-FourTorr), 1700 ° C,
Silicon carbide was sublimated and decomposed under the conditions of 30 minutes. Film on substrate
Was observed with a transmission electron microscope, as shown in FIG.
Oriented carbon nanotube film perpendicular to a transparent substrate
3 was obtained.

Example 2 A Ti ₆ Al ₄ V plate having a mirror-polished surface was used as a substrate. First, a silicon carbide polycrystal was deposited to a thickness of 200 μm by microwave plasma CVD. The substrate was degreased by ultrasonic cleaning with ethanol and then acetone, and then placed in a reaction tube and heated at 360 ° C. for 30 minutes in hydrogen plasma. At this time, the microwave output was 200 W. After the substrate temperature was stabilized, a source gas was introduced, and film formation was started. CH ₃ as source gas for C
Cl was used and SiH ₄ was used as a Si source gas. The source gas was supplied from a cylinder diluted and filled to 10% with hydrogen, and was mixed with hydrogen of the carrier gas before entering the reaction chamber. Each gas flow rate was 110 sccm for H _{2 and} 0.1 for SiH ₄ .
41 sccm and 0.73 sccm of CH ₃ Cl. After depositing a film of about 0.5 μm, the substrate was taken out. According to X-ray diffraction, as shown in FIG.
The (111) peak was dominant. In addition, spots due to <111> orientation were confirmed by high-speed electron diffraction. Therefore, it was considered that the deposited film was strongly oriented to <111> in β-SiC. Thereafter, the substrate is exposed to a concentration of 19
The substrate was dissolved in specified sulfuric acid to dissolve the substrate, and the silicon carbide film was separated. Then, in a vacuum (1 × 10 ⁻⁴ Torr), 17
Silicon carbide was sublimated and decomposed at 00 ° C. for 30 minutes. Observation of the film on the substrate with a transmission electron microscope revealed that a carbon nanotube film oriented perpendicular to the substrate could be obtained.

Example 3 An Al plate whose surface was mirror-polished was used as a substrate. First,
A silicon carbide polycrystal was deposited to a thickness of 500 μm by microwave plasma CVD. The substrate was degreased by ultrasonic cleaning with ethanol and then with acetone, and then placed in a reaction tube and heated at 300 ° C. for 30 minutes in hydrogen plasma. The microwave output at this time is 180W
Met. After the substrate temperature stabilizes, source gas is introduced,
Film formation was started. CH ₃ Cl as a raw material gas of C, S
SiH ₄ was used as a source gas for i. The raw material gas was supplied from a cylinder diluted and filled to 10% with hydrogen, and mixed with hydrogen of the carrier gas before entering the reaction chamber. Each gas flow rate is 110 sccm for H _{2 and} 0.41 scc for SiH ₄
m, CH ₃ Cl was 0.77 sccm. After depositing a film of about 0.5 μm, the substrate was taken out. According to the X-ray diffraction, although the diffraction peak of β-SiC (200) was observed as shown in FIG. 4, the peak of β-SiC (111) was dominant. In high-speed electron diffraction, <1
11> A spot due to orientation was confirmed. Therefore, it was considered that the deposited film was strongly oriented to <111> in β-SiC. Thereafter, the substrate was immersed in sulfuric acid having a concentration of 19 N to dissolve the substrate and separate the silicon carbide film. Then, in a vacuum (1 × 10 ⁻⁴ Torr), 1700 ° C., 30
The silicon carbide was sublimated and decomposed under the conditions of minutes. Observation of the film on the substrate with a transmission electron microscope revealed that a carbon nanotube film oriented perpendicular to the substrate could be obtained.

Effects of the embodiment As shown in the above embodiment, using various types of substrates,
The carbon nanotube alignment film was easily manufactured. It is considered that the carbon nanotube film manufactured in this manner can maximize the excellent functional characteristics of the carbon nanotube.

The present invention is not limited to the above embodiment, but may be variously modified within the scope of the present invention according to the purpose and application. For example, a carbon nanotube film-containing SiC substrate and a carbon nanotube film can be used by bonding a support plate made of ceramics, metal, or the like. In this case, it may have a three-layer structure of a carbon nanotube film, a silicon carbide polycrystalline film, and a support plate, or may have a two-layer structure of a carbon nanotube film and a support plate. Further, the both sides of the carbon nanotube film body may be covered with two support plates. These forms may be any of a plate shape, a film shape, a cylindrical shape, and the like, and the surface may be a smooth surface or an uneven surface.

The carbon nanotubes, the carbon nanotube film-containing SiC substrate and the carbon nanotube film can be obtained not only by heating in a vacuum but also by heating in an atmosphere containing oxygen. The "oxygen-containing atmosphere" is preferably an inert gas atmosphere under normal pressure. The amount of oxygen contained in the inert gas atmosphere is not particularly limited, but is preferably 3% or less, more preferably 1% or less. However, the lower limit is usually 0.1%. If the amount of oxygen is too large, the carbon nanotubes are etched, which is not preferable.
The inert gas includes He and Ar, but Ar is preferably used. Even in an inert gas containing a trace amount of oxygen instead of a vacuum, the same effect is obtained because SiO evaporates.

[0029]

The carbon nanotube film and the carbon nanotube film-containing SiC substrate of the present invention are useful for forming a large-area film because the carbon nanotubes are vertically oriented with respect to the silicon carbide polycrystalline film. Moreover, according to the method for producing a carbon nanotube film and the method for producing a carbon nanotube film-containing SiC substrate of the present invention, a carbon nanotube film vertically oriented with respect to the substrate can be easily produced with a large area. In particular, since it is not necessary to perform epitaxial growth in order to obtain a silicon carbide polycrystalline film as a raw material, an amorphous substrate is used as long as it has low reactivity with silicon carbide during deposition and can be separated from the silicon carbide film in the etching step. Many materials such as materials and metal materials can be used, and there is no need to use expensive single crystal wafers. Therefore, the manufacturing cost can be significantly reduced as compared with the related art. Further, it is possible to obtain a carbon nanotube film in which the orientation of the carbon nanotube is not disturbed even if the area of the silicon carbide polycrystalline film is large. Furthermore, according to the carbon nanotube film of the present invention, since it is an aggregate of only carbon nanotubes,
Utilizing its characteristics, it is very useful for gas separation membranes.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a method for manufacturing a carbon nanotube film of Example 1.

FIG. 2 is a transmission electron micrograph of a cross section of the carbon nanotube film of Example 1.

FIG. 3 is an X-ray diffraction pattern of a silicon carbide film of Example 2.

FIG. 4 is an X-ray diffraction pattern of a silicon carbide film of Example 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Substrate, 2; Silicon carbide polycrystal film, 2a; Silicon carbide polycrystal film body, 2b; Silicon carbide polycrystal base, 3: Carbon nanotube film.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G046 CA00 CB03 CC02 CC03 CC06 4K030 AA03 AA06 AA09 AA17 BA37 BB03 CA02 CA06 DA03 DA08 FA01 JA10

Claims (15)

[Claims] A polycrystalline film made of silicon carbide is formed on a substrate, and then the substrate on which the polycrystalline silicon carbide film is formed is immersed in a processing liquid to separate the polycrystalline silicon carbide film from the substrate. And then heating the silicon carbide polycrystalline film separated in vacuum to a temperature at which silicon carbide is decomposed and silicon atoms are lost from the surface of the silicon carbide polycrystalline film, thereby converting silicon atoms from silicon carbide. A carbon nanotube film comprising a large number of carbon nanotubes formed by removing and growing from the surface to the inside of the silicon carbide polycrystalline film. 2. When the silicon carbide is α-SiC,
The carbon nanotube film according to claim 1, wherein the carbon nanotubes are oriented perpendicular to the (0001) plane. 3. When the silicon carbide is β-SiC,
The carbon nanotube film according to claim 1, wherein the carbon nanotubes are oriented perpendicular to the (111) plane. 4. The carbon nanotube film according to claim 1, wherein the heating temperature is 1200 to 2000 ° C. 5. A polycrystalline film made of silicon carbide is formed on a substrate, and then the substrate on which the silicon carbide polycrystalline film is formed is immersed in a processing liquid to separate the silicon carbide polycrystalline film from the substrate. And then heating the silicon carbide polycrystalline film separated in vacuum to a temperature at which silicon carbide is decomposed and silicon atoms are lost from the surface of the silicon carbide polycrystalline film, thereby converting silicon atoms from silicon carbide. A method for producing a carbon nanotube film, comprising: forming a carbon nanotube film composed of a large number of carbon nanotubes grown from the surface to the inside of the silicon carbide polycrystalline film body by removing the film. 6. A silicon carbide polycrystalline film is formed on a substrate, and then the substrate on which the silicon carbide polycrystalline film is formed is immersed in a treatment liquid to separate the silicon carbide polycrystalline film from the substrate. Then, the separated silicon carbide polycrystalline film body, a carbon nanotube film obtained by heating the silicon carbide polycrystalline substrate to a temperature at which silicon atoms are lost in vacuum,
And a silicon carbide polycrystal base located below the carbon nanotube film. 7. When the silicon carbide is α-SiC,
7. The carbon nanotube film-containing substrate according to claim 6, wherein the carbon nanotubes are oriented perpendicular to the (0001) plane. 8. When the silicon carbide is β-SiC,
The carbon nanotube film-containing substrate according to claim 6, wherein the carbon nanotubes are oriented perpendicular to the (111) plane. 9. The carbon nanotube film-containing substrate according to claim 6, wherein the heating temperature is 1200 to 2000 ° C. 10. A polycrystalline film made of silicon carbide is formed on a substrate, and then the substrate on which the silicon carbide polycrystalline film is formed is immersed in a processing liquid to separate the silicon carbide polycrystalline film from the substrate. Then, the separated silicon carbide polycrystalline film body is heated under vacuum to a temperature at which the silicon carbide polycrystalline substrate loses silicon atoms, and a carbon nanotube film obtained by heating the silicon carbide polycrystalline substrate is positioned below the carbon nanotube film. And a silicon carbide polycrystal base, comprising: a carbon nanotube film-containing SiC substrate; 11. A polycrystalline film made of silicon carbide is formed on a substrate, and thereafter, the substrate on which the silicon carbide polycrystalline film is formed is immersed in a treatment liquid to separate the silicon carbide polycrystalline film from the substrate. Then, by heating the silicon carbide polycrystalline film separated in vacuum to a temperature at which silicon carbide is decomposed and silicon atoms are lost from the surface of the silicon carbide polycrystalline film,
A carbon nanotube film comprising a large number of carbon nanotubes by completely removing silicon atoms from silicon carbide. 12. The carbon nanotube film according to claim 11, wherein when the silicon carbide is α-SiC, the carbon nanotubes are oriented in a (0001) plane. 13. The carbon nanotube film according to claim 11, wherein when the silicon carbide is β-SiC, the carbon nanotubes are oriented in a (111) plane. 14. The heating temperature is 1200 to 2000 ° C.
The carbon nanotube film according to any one of claims 11 to 13, wherein 15. A silicon carbide polycrystalline film is formed on a substrate, and then the substrate on which the silicon carbide polycrystalline film is formed is immersed in a treatment liquid to separate the silicon carbide polycrystalline film from the substrate. Then, by heating the silicon carbide polycrystalline film separated in vacuum to a temperature at which silicon carbide is decomposed and silicon atoms are lost from the surface of the silicon carbide polycrystalline film,
A method for producing a carbon nanotube film, comprising completely removing silicon atoms from silicon carbide to form a carbon nanotube film composed of only a large number of carbon nanotubes.