KR20170003670A - Method for producing graphene - Google Patents

Abstract

The graphene manufacturing method includes a carbon-containing layer forming step of forming a carbon-containing layer 7 on the base layer 1 by atomic layer deposition, a first heat-treating step of forming an amorphous carbon layer 9 from the carbon- And a second heat treatment step of forming graphenes 11 from the amorphous carbon layer. The temperature in the first heat treatment step is preferably 600 ° C or lower. When the carbon-containing layer contains a polymer, it is preferable that the number of aromatic rings contained in the monomer constituting the polymer is 1 or less.

Description

[0001] METHOD FOR PRODUCING GRAPHENE [0002]

This application is based on Japanese Patent Application No. 2014-221380, filed on October 30, 2014, the content of which is incorporated herein by reference.

This disclosure relates to a method of making graphene.

Since graphene has excellent properties, its use for various purposes has been studied. As a manufacturing method of graphene, there has been proposed a method of forming an organic polymer film by spin coating and then heat-treating the organic polymer film (see Patent Document 1).

WO2011 / 025045

In the technique described in Patent Document 1, it has been difficult to produce graphene having uniform film thickness. The present disclosure aims at providing a method for producing graphene capable of producing graphene having uniform film thickness.

According to an aspect of the present disclosure, a method of manufacturing graphene includes a carbon-containing layer formation step of forming a carbon-containing layer on an underlayer by atomic layer deposition, a first heat treatment step of forming an amorphous carbon layer as the carbon- And a second heat treatment step of forming graphene with the amorphous carbon layer. According to the method for producing graphene according to an aspect of the present disclosure, graphene having a uniform film thickness can be produced.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings.
1A is a cross-sectional view showing a configuration of a sapphire substrate having a base layer.
1B is a cross-sectional view showing a self-assembled monolayer formation process.
1C is a cross-sectional view showing a step of forming a carbon-containing layer.
1D is a cross-sectional view showing a first heat treatment process.
1E is a cross-sectional view showing a second heat treatment process.
Fig. 2 is an explanatory diagram showing the results of analysis of graphene produced in Example 1 by Raman spectroscopy. Fig.
3 is an explanatory view showing the result of analysis of the amorphous carbon layer formed by the first heat treatment step by Raman spectroscopy.
4 is an explanatory diagram showing the results of analysis of graphene produced in the comparative example by Raman spectroscopy.

Embodiments of the present disclosure will be described. In the carbon-containing layer formation step, a carbon-containing layer is formed on the base layer by atomic layer deposition (ALD). The conditions in the step of forming the carbon-containing layer can be, for example, as follows.

Substrate temperature: 50 to 500 占 폚.

Pressure: 0.1 Pa to atmospheric pressure.

Materials used to form carbon-containing layers: terephthalic acid dichloride, ethylenediamine.

As a material used for forming the carbon-containing layer, it is preferable to use two or more kinds (for example, terephthalic acid dichloride and ethylenediamine) in combination.

Examples of the material of the carbon-containing layer include polyamide (PA), polyimide (PI), polyethylene terephthalate (PET), acrylic resin (PMMA) and polycarbonate (PC). The material of the carbon-containing layer may be a compound of a metal and carbon (for example, AlCHO). The film thickness of the carbon-containing layer may be, for example, from several nm to several hundreds nm. In the present specification, the film thickness means a value measured by using an apparatus of ellipsometry.

The carbon-containing layer may comprise, for example, a polymer. In this case, the number of aromatic rings (for example, benzene ring, naphthalene ring, anthracene ring, etc.) contained in the monomers constituting the polymer is preferably 1 or less. When the number of aromatic rings contained in the monomer constituting the polymer is 1 or less, the carbon amount per unit area in the carbon-containing layer becomes more uniform. As a result, uniformity of film thickness of graphene is further improved.

The carbon-containing layer may be formed directly on the base layer, or may be formed on the self-assembled monolayer when the base layer has a self-organizing monolayer.

As the material of the underlayer, for example, at least two kinds of alloys of Co, Fe, Ni, Cu, Ru, Rh, Pd, Pt, Au, Ir, Sc, Ti, Al, Ag, Mn, Cr, . The film thickness of the base layer can be, for example, several nm to several hundreds nm. The underlayer can be formed by, for example, a vapor deposition method, a sputtering method, a CVD method, or an atomic layer deposition (ALD) method.

The base layer can be formed, for example, on a substrate. As the material of the substrate, for example, sapphire, magnesium oxide, quartz, Si and the like can be given. In the case of a Si substrate, an SiO ₂ film may be provided on the surface.

In the first heat treatment step, an amorphous carbon layer is formed from the carbon-containing layer. The amorphous carbon layer is a layer at least a part of which is amorphous carbon. The temperature in the first heat treatment step is preferably 600 占 폚 or lower, more preferably 50 占 폚 to 600 占 폚. Within this range, the amount of impurities (O, N, H, etc.) derived from the carbon-containing layer remaining in graphene can be further reduced.

The time of the first heat treatment step may be, for example, 0.1 to 100 hours. Within this range, the film quality of graphene is further improved. The atmospheric gas in the first heat treatment step may be, for example, an inert gas (e.g., N ₂ , Ar, etc.). When the atmospheric gas is an inert gas, the film quality of the graphene is further improved. The pressure in the first heat treatment step may be, for example, atmospheric pressure or reduced pressure (for example, 10 ^-6 to 10 ⁵ Pa). In this case, the film quality of graphene is further improved.

It is preferable that at least the carbon-containing layer formation step and the first heat treatment step are continuously performed in vacuum in the production process of graphene. In this case, unnecessary mixing of the carbon source can be suppressed, so that the film thickness of the graphene can be more accurately controlled. In this specification, the term " continuous " means treatment without being exposed to the atmosphere.

In the second heat treatment step, graphene is formed by an amorphous carbon layer. The graphene may be a carbon crystal structure of a monoatomic layer or a carbon crystal structure of a plurality of atomic layers. The plurality of atomic layers are, for example, nine or less atomic layers. The carbon crystal structure of a plurality of atomic layers may be referred to as a multi-layer graphene or a stacked graphene.

The temperature in the second heat treatment step is preferably higher than 600 ° C and not higher than 1200 ° C. Within this range, the film quality of graphene is further improved.

The time of the second heat treatment step may be, for example, 0.1 to 100 hours. Within this range, the film quality of graphene is further improved. The second heat treatment step may be performed in a vacuum or in an atmospheric gas. As the atmospheric gas, for example, an inert gas (for example, N ₂ , Ar, etc.) can be mentioned. When the second heat treatment step is performed in vacuum or in the atmosphere gas described above, the film quality of the graphene is further improved. The pressure in the second heat treatment step may be, for example, atmospheric pressure or reduced pressure (for example, 10 ^-6 to 10 ⁵ Pa). In this case, the film quality of graphene is further improved.

It is preferable that at least the steps from the first heat treatment step to the second heat treatment step are continuously performed in vacuum in the manufacturing process of graphene. In this case, unnecessary mixing of the carbon source can be suppressed, so that the film thickness of the graphene can be more accurately controlled.

A self-organizing monolayer may be formed between the base layer and the carbon-containing layer. The self-organizing monolayer promotes bonding between the material used to form the carbon-containing layer and the ground layer. As a result, the film thickness of the carbon-containing layer hardly changes in the initial stage of formation of the carbon-containing layer. As a result, variation in the film thickness of graphene can be suppressed.

Examples of the material of the self-organizing monolayer include APS (3-aminopropyltriethoxysilane) and AEAPS (3- (2-aminoethyl) -aminopropyltrimethoxysilane). The thickness of the self-assembled monolayer may be, for example, 0.01 to 100 nm.

As a method of forming the self-assembled monolayer, for example, there are a dry system in which monomolecular monomolecules (molecules constituting a self-organizing monolayer) are vapor-fed into a substrate, a wet system in which the substrate is immersed in a liquid containing a self- .

It is preferable that the functional group contained in the self-organizing monolayer is combined with a functional group contained in the carbon-containing layer. In this case, fluctuations in the film thickness of graphene can be further suppressed.

It is preferable to form a self-organizing monolayer in a vacuum, to form a self-organizing monolayer, and to carry out a carbon-containing layer forming process continuously. In this case, unnecessary mixing of the carbon source can be suppressed, so that the film thickness of the graphene can be more accurately controlled.

(Example 1)

1. Manufacturing method of graphene

First, as shown in Fig. 1A, a sapphire substrate 3 provided with a ground layer 1 made of Co was prepared. The film thickness of the ground layer 1 is 200 nm.

Then, as shown in Fig. 1B, a self-organizing monolayer 5 was formed on the base layer 1. Then, as shown in Fig. Hereinafter, this step is referred to as a self-assembled monolayer formation step. The material of the self-assembled monolayer 5 is APS. The film thickness of the self-assembled monolayer 5 is 2 nm. The self-organizing monolayer 5 was formed by a dry method of vapor-supplying monomolecular monomers.

Then, as shown in Fig. 1C, a carbon-containing layer 7 was formed on the self-assembled monolayer 5 by atomic layer deposition. Hereinafter, this step is referred to as a step of forming a carbon-containing layer. The carbon-containing layer formation process was performed in succession to the self-organizing monolayer formation process. Conditions for the atomic layer deposition method were as follows.

Substrate temperature: 120 占 폚.

Pressure: 133 Pa.

Materials used to form carbon-containing layer (7): terephthalic acid dichloride and ethylenediamine.

The material of the carbon-containing layer 7 is PA. The film thickness of the carbon-containing layer 7 is 4 nm. The carbon-containing layer 7 contains a polymer of PA, but monomers constituting the polymer include one aromatic ring.

Subsequently, the first heat treatment step was carried out in succession to the carbon-containing layer formation step. The conditions of the first heat treatment step are as follows.

Temperature: 600 ° C

Time: 10 minutes

Atmosphere gas: Vacuum

Pressure: less than 1 x ^10-3 Pa

As a result, as shown in Fig. 1D, the amorphous carbon layer 9 is formed of the carbon-containing layer 7.

Subsequently, a second heat treatment step was performed in succession to the first heat treatment step. The conditions of the second heat treatment step are as follows.

Temperature: 800 ° C

Time: 20 minutes

Atmosphere gas: Vacuum

Pressure: less than 1 x ^10-3 Pa

As a result, as shown in FIG. 1E, the graphene 11 was formed as the amorphous carbon layer 9.

2. Evaluation of graphene

The graphene thus prepared was analyzed by Raman spectroscopy. The results are shown in Fig. The waveform shown in Fig. 2 was specific to graphene. Thus, it was confirmed that graphene could be produced by the above-described production method.

Further, in the waveform of FIG. 2, the ratio of G band that appears in the 2D band 1580㎝ ^-1 vicinity appear at ^-1 2700㎝ was 2D / G = 2.5. From this, it was confirmed that the film thickness of graphene was uniform.

Further, in the waveform of FIG. 2, the ratio of D band to G band that appears near the 1300㎝ ^-1 appears at 1580㎝ ^-1 was a G / D = 26. From this, it was confirmed that the film quality of graphene was good.

Further, the layer generated by the first heat treatment step was analyzed by Raman spectroscopy. The results are shown in Fig. The waveform shown in Fig. 3 was specific to amorphous carbon. Therefore, it was confirmed that the amorphous carbon layer was formed by the first heat treatment step.

3. Effect of manufacturing method of graphene

According to the method for producing graphene of this embodiment, graphene having uniform film thickness and good film quality can be produced. Further, according to the graphene manufacturing method of this embodiment, the film thickness of the graphene can be precisely controlled.

(Comparative Example)

1. How to deposit

Basically, it is the same as that of Example 1, but the second heat treatment step was carried out immediately after the carbon-containing layer forming step and without carrying out the first heat treatment step.

2. Evaluation of membrane

The formed film was analyzed by Raman spectroscopy. The results are shown in Fig. The waveform shown in Fig. 4 has a feature that the intensity of the D band with respect to the G band is high. From this, it can be seen that graphene, which is very poor in film quality, is generated in this comparative example.

(Example 2)

Basically, graphene is produced in the same manner as in Example 1 above. However, in this embodiment, the material of the carbon-containing layer 7 is PET. Further, when the material used for forming the carbon-containing layer 7 is ethylene glycol rather than ethylenediamine, the material of the carbon-containing layer 7 can be PET. Also in this embodiment, graphene substantially the same as in Embodiment 1 can be produced.

(Example 3)

Basically, graphene is produced in the same manner as in Example 1 above. However, in this embodiment, the temperature in the first heat treatment step was set to 500 캜. Also in this embodiment, it is possible to manufacture graphene substantially the same as in the first embodiment.

(Example 4)

Basically, graphene is produced in the same manner as in Example 1 above. However, in this embodiment, the temperature in the second heat treatment step was set at 750 캜. Also in this embodiment, it is possible to manufacture graphene substantially the same as in the first embodiment.

(Example 5)

Basically, graphene is produced in the same manner as in Example 1 above. However, in this embodiment, formation of the self-organizing monolayer 5 is omitted. Therefore, in this embodiment, the carbon-containing layer 7 is formed directly on the ground layer 1. [ Also in this embodiment, it is possible to manufacture graphene substantially the same as in the first embodiment.

(Example 6)

Basically, graphene is produced in the same manner as in Example 1 above. However, in this embodiment, the foundation layer 1 is made of Ni. Also in this embodiment, it is possible to manufacture graphene substantially the same as in the first embodiment.

Although the embodiment of the present disclosure has been described above, the present invention is not limited to the above embodiment, and various forms can be employed.

For example, in Examples 1 to 6, the film thickness of the carbon-containing layer 7 may be a value other than 4 nm, for example, 40 to 50 nm (for example, 46 nm).

The functions of one component in the above embodiment may be dispersed as a plurality of components or the functions of a plurality of components may be integrated into one component. Note that a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Further, a part of the configuration of the embodiment may be omitted. Note that at least a part of the configuration of the above embodiment may be added or substituted for the configuration of another embodiment. In addition, all the forms included in the technical idea specified only by the words in the claims are embodiments of the present disclosure.

In addition to the above-described method for producing graphene, the present disclosure can be realized in various forms such as graphene and graphene production apparatuses.

Claims (8)

A carbon-containing layer forming step of forming a carbon-containing layer (7) on the base layer (1) by atomic layer deposition;
A first heat treatment step of forming an amorphous carbon layer 9 as the carbon-containing layer,
And a second heat treatment step of forming a graphene (11) with the amorphous carbon layer. The method for producing graphene according to claim 1, wherein the temperature in the first heat treatment step is 600 占 폚 or lower. 3. The method for producing graphene according to claim 1 or 2, wherein when the carbon-containing layer comprises a polymer, the number of aromatic rings contained in the monomer constituting the polymer is 1 or less. The method for producing graphene according to any one of claims 1 to 3, wherein a self-organizing monolayer (5) is formed between the base layer and the carbon-containing layer. 5. The method for producing graphene according to claim 4, wherein the functional group contained in the self-organizing monolayer is bonded to the functional group contained in the carbon-containing layer. 6. The method of claim 4 or 5, wherein the self-assembled monolayer is formed in a vacuum,
Wherein the step of forming the self-assembled monolayer and the step of forming the carbon-containing layer are continuously performed. The method for producing graphene according to any one of claims 1 to 6, wherein at least the steps from the carbon-containing layer formation step to the first heat treatment step are continuously performed in vacuum. The method for producing graphene according to any one of claims 1 to 7, wherein at least the steps from the first heat treatment step to the second heat treatment step are continuously performed in vacuum.

Images