KR20160043797A - Manufacturing method of graphene laminated structure, and graphene laminated structure using thereof - Google Patents

Abstract

The present invention relates to a preparation method of a stacked graphene structure and a stacked graphene structure prepared by the same. More particularly, the present invention relates to a preparation method of a stacked graphene structure, which coats a metal catalyst on graphene and forms graphene on top of the coated metal catalyst; and to a stacked graphene structure prepared by the same. The stacked graphene structure compensates defects of graphene and has improved electric conductivity without degradation of transmittance.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a graphene laminated structure, and a graphene laminated structure produced thereby,

The present invention relates to a method of manufacturing a graphene laminate structure and a graphene laminate structure manufactured thereby, and more particularly, to a method of manufacturing a graphene laminate structure by coating a metal catalyst on graphene, To a method for manufacturing a graphene laminated structure improved in electric conductivity without decreasing the transmittance and a graphene laminated structure manufactured thereby.

Graphene is a conductive material with a thickness of one atom, with the carbon atoms forming a honeycomb arrangement in a two-dimensional fashion. Unlike graphite, has a characteristic that it is thinly formed from a single layer to several layers. Since such graphene is flexible and highly transparent and highly transparent, studies are underway to use it as a transparent and bending electrode or as an electron transport material such as an electron transport layer in an electronic device.

Examples of the method for producing such graphene include mechanical peeling, organic solvent, chemical vapor deposition (CVD), and chemical method through oxidation-reduction.

Graphene has attracted great attention as an electron transport layer and a transparent electrode of an electronic device that uses a photovoltaic power principle that receives light and converts it into electricity, such as a solar cell or a photodetector. ITO and the like are widely used as transparent electrodes of electronic devices. However, due to the increase in price of main materials and the possibility of depletion, manufacturing costs are increasing, and since they are not flexible, they are difficult to apply to bent devices.

Therefore, in spite of the excellent electrical / mechanical / chemical properties of graphene, mass synthesis method has not been developed in the meantime, so research on practical applicable technology is very limited. In the conventional mass synthesis method, graphite was mechanically pulverized and dispersed in a solution, followed by self-assembly to form a thin film. The advantage of being able to synthesize at a relatively low cost, however, is that the electrical and mechanical properties of the graphene pieces are not as expected due to the overlapping structure of the graphene pieces.

At present, a variety of techniques have been developed for a method of manufacturing graphene using chemical vapor deposition (CVD). For example, Korean Patent Registration No. 10-0923304 (Patent Document 1) discloses a method for economically manufacturing a large-area graphene sheet by chemical vapor deposition (CVD) in which a graphitizing catalyst is formed into a film shape, Korean Patent Laid-Open Publication No. 10-2013-0001253 (Patent Document 2) discloses a carbon film laminate for producing graphene using a copper thin film formed by epitaxial growth on a single crystal substrate as a catalyst.

However, the presently known graphene synthesis method grows into a polycrystalline structure having defects such as dislocations and grain boundaries, and these defects may deteriorate the properties of graphene. In order to overcome these defects, graphene was synthesized by doping metal nanoparticles or using metal nanowires or carbon nanotubes. However, there was still a problem of difficulty in mass production because the permeability was lowered and the manufacturing method became complicated. Therefore, research on graphene which can improve the electric conductivity while maintaining the permeability and which can be mass-produced economically is emerging.

Korean Patent No. 10-0923304 Korean Patent Publication No. 10-2013-0001253

In order to solve the above-mentioned problems, the present invention provides a method of manufacturing a semiconductor device, comprising: coating a metal catalyst on a graphene and forming a graphene on the coated metal catalyst to compensate for defects of the graphene, And to provide a method of manufacturing a structure.

More specifically, it is possible to uniformly coat the metal catalyst by a simple method by immersing the synthesized graphene in a metal catalyst solution and coating the graphene growth seed, and the dislocation and grain boundary of the graphene The present invention provides a method for manufacturing a graphene laminated structure which can economically mass-produce a graphene laminated structure improved in electric conductivity without decreasing the transmittance.

Another object of the present invention is to provide a graphene laminated structure excellent in transmittance and electrical conductivity produced by the above-described method.

According to an aspect of the present invention, there is provided a method of manufacturing a thin film transistor, including: forming a first graphene layer on a metal thin film; b) immersing the first graphene in a metal catalyst solution to form a graphene growth seed; And c) forming a second graphene layer on the surface of the first graphene having the graphene growth seed formed thereon.

According to an embodiment of the present invention, the metal catalyst solution includes a metal chloride and a solvent, and the metal chloride may be at least one selected from the group consisting of nickel (Ni), copper (Cu), platinum (Pt), palladium (Pd), cobalt , Iron (Fe), and gold (Au).

According to one embodiment of the present invention, the solvent may comprise at least one protonic solvent selected from water, (C1-C7) lower alcohols or mixtures thereof.

According to an embodiment of the present invention, the concentration of the metal catalyst solution may be 0.01 to 2.0 mol / L.

According to an embodiment of the present invention, the first graphene layer in the step a) and the second graphene layer in the step c) are formed by a chemical vapor deposition method, and the chemical vapor deposition method includes a high temperature chemical vapor deposition, Chemical vapor deposition, low pressure chemical vapor deposition, atmospheric pressure chemical vapor deposition, metal organic chemical vapor deposition, and plasma chemical vapor deposition.

According to an embodiment of the present invention, the metal thin film may be selected from a copper foil, a nickel foil, or an alloy foil of copper and nickel.

According to an embodiment of the present invention, the first graphene layer in step a) and the second graphene layer in step c) are chemically implanted with a solution of hydrogen: argon: a chemical which is injected with carbon source in a ratio of 10: 800 to 1200: 20 to 40 sccm And may be formed by a vapor deposition method.

In order to accomplish the above object, the present invention relates to a graphene laminated structure manufactured by the manufacturing method described above.

According to an embodiment of the present invention, the graphene laminated structure may have a permeability of 97% or more and a sheet resistance of 500? /? Or less.

According to one embodiment of the present invention, the graphene laminate structure may be applied to at least one selected from a thin film transistor, a memory device, a transparent electrode, a photodetector, a semiconductor device, or a light emitting diode.

According to the method of producing a graphene laminate structure of the present invention and the graphene laminate structure produced by the method of the present invention, a metal catalyst is coated on graphene and graphenes are formed on the coated metal catalyst to improve electrical conductivity without decreasing the permeability .

Rather than forming a metal catalyst thin film by a conventional sputtering, chemical vapor deposition or epitaxial growth method, the present invention can provide a method for producing graphene having improved economy by a simple method by immersing the metal catalyst in a metal catalyst solution and coating the metal catalyst There are advantages.

Further, by manufacturing the graphene laminated structure according to the present invention, it is possible to prevent defects such as dislocations and grain boundaries of conventional large area graphene, and to improve physical properties.

It can be applied to various electronic device materials such as a thin film transistor, a memory device, a transparent electrode, a photodetector, a semiconductor device, or a light emitting diode, while the electrical conductivity is remarkably improved while maintaining excellent transmittance.

1 is a flowchart illustrating a method of manufacturing a graphene laminated structure according to an embodiment of the present invention.
FIG. 2 is a scanning electron microscope (SEM) image of a surface profile of a graphene laminate structure according to an exemplary embodiment of the present invention, wherein a) is a first graphene layer and b) And c) and d) are graphene laminated structures in which a second graphene layer is formed on the surface of the first graphene on which the graphene growth seed is formed.
3 is a graph illustrating sheet resistance of a graphene laminate structure according to an embodiment of the present invention.
FIG. 4 is a graph showing a measurement of transmission of a graphene laminated structure according to an embodiment of the present invention.
5 is a graph illustrating a Raman measurement result of the graphene laminated structure according to an embodiment of the present invention.
FIG. 6 shows electrical characteristics of the graphene laminate structure according to an embodiment of the present invention.

Hereinafter, a method for producing a graphene laminated structural body of the present invention and a graphene laminated structural body produced by the method will be described in detail. The present invention may be better understood by the following examples, which are for the purpose of illustrating the present invention and are not intended to limit the scope of protection defined by the appended claims.

The present invention relates to a method of coating a metal catalyst on a graphene by dipping the metal catalyst on the graphene and forming a graphene on the coated metal catalyst in a simple and economical manner, The present invention has been accomplished based on the discovery that a graphene laminated structure having improved electrical conductivity can be produced.

Hereinafter, one embodiment of the present invention will be described in more detail.

The present invention

a) forming a first graphene layer on the metal thin film;

b) immersing the first graphene in a metal catalyst solution to form a graphene growth seed; And

and c) forming a second graphene layer on the surface of the first graphene having the graphene growth seed formed thereon.

A method of fabricating a graphene laminate structure according to an embodiment of the present invention may include the steps of: a) forming a first graphene layer on a metal thin film.

The metal thin film may be glass, quartz, silicon, carbon felt, sapphire, silicon nitride, copper foil, nickel foil or the like, although it is not limited as long as it is a substrate that forms graphene and is used in the art. And an alloy foil of copper and nickel. Preferably a copper foil, a nickel foil or an alloy foil of copper and nickel. More preferably, the copper foil is effective to form a single-layer graphene, and is more effective than the graphene formed in a multi-layer because of its superior optical and electrical properties.

According to an embodiment of the present invention, the method of forming the first graphene layer on the metal thin film is not limited as long as it is a commonly used method for growing graphene in the related art. For example, a chemical vapor deposition method Chemical Vapor Deposition (CVD). The chemical vapor deposition may be performed by a rapid thermal chemical vapor deposition (RTCVD) method, an inductively coupled plasma-chemical vapor deposition (ICP-CVD) method, or a low pressure chemical vapor deposition method. (LPCVD), Atmospheric Pressure Chemical Vapor Deposition (APCVD), Metal Organic Chemical Vapor Deposition (MOCVD), and Plasma-enhanced chemical vapor deposition (PECVD) May be selected from two or more combinations.

The first graphene layer may be formed by reacting and reacting with a reactive gas containing a carbon source, but is not limited thereto. For example, the carbon source may be selected from one or more of carbon monoxide, carbon dioxide, methane, ethane, ethylene, ethanol, acetylene, propane, butane, butadiene, pentane, pentene, hexane, cyclohexane, benzene and toluene have. More preferably methane, ethane or a mixture thereof.

Although not limited to form the first graphene layer, a hydrogen: argon: carbon source may be implanted at 10: 800-1200: 20 to 40 sccm. More preferably, hydrogen: argon: carbon source can be implanted at 10: 900 to 1100: 25 to 35 sccm.

When the carbon source is heat-treated at a temperature of about 800 to 1200 ° C while supplying the gaseous phase, the carbon components present in the carbon source combine to form a hexagonal honeycomb-like plate-like structure and graphene can grow. More preferably at a temperature of 900 to 1100 < 0 > C, but is not limited thereto.

First, a metal thin film is placed in a reactor, heated to a heat treatment temperature together with a reaction gas, and then injected with a carbon source to form graphene. Raising the temperature of the metal thin film to the heat treatment temperature together with the reaction gas is an attempt to facilitate formation of a single layer of graphene by forming an environment capable of reaction between the metal thin film and the gas mixed with the reaction gas and the carbon source.

The reaction gas may be a mixed gas of hydrogen and an inert gas, but is not limited thereto. As an example, a mixed gas of hydrogen and argon gas may be used.

According to an embodiment of the present invention, a reactor containing a metal thin film may be heated to a heat treatment temperature, and then a carbon source may be injected into the reactor to synthesize graphene for 1 to 60 minutes, but the present invention is not limited thereto.

According to an embodiment of the present invention, the method may further include a step of cooling to room temperature after synthesizing the first graphene. In the present invention, the normal temperature may mean a temperature of 15 to 40 DEG C, but is not limited thereto.

The method of fabricating a graphene laminate structure according to an embodiment of the present invention may include b) dipping the first graphene in a metal catalyst solution to form a graphene growth seed.

Conventionally, a metal catalyst is formed as a thin film on the first graphene layer by chemical vapor deposition, sputtering, thermal evaporation, electron beam evaporation, or pulsed laser deposition, but the method is complicated and costly, There was a difficult problem. In order to solve this problem, it has been found that the graphene seeds can be uniformly formed by immersing the first graphene in the metal catalyst solution and coating the metal catalyst.

According to an embodiment of the present invention, the metal catalyst solution may include a metal chloride and a solvent. The metal chloride may include one or more metals selected from the group consisting of nickel (Ni), copper (Cu), platinum (Pt), palladium (Pd), cobalt (Co), iron (Fe) , But is not limited thereto. Preferably, a chloride of nickel (Ni) is effective because it can easily form nanoparticles, which are growth seeds that easily serve as a graphene catalyst on the surface of graphene.

The solvent is not limited as long as it is a solvent capable of dissolving or dispersing the metal chloride. For example, at least one protonic solvent selected from water, (C1-C7) lower alcohols or mixtures thereof. More preferably, it is methanol or ethanol.

The concentration of the metal catalyst solution is not limited, but may be 0.01 to 2.0 mol / L. More preferably 0.1 to 1.0 mol / L. When the concentration of the metal catalyst solution is less than 0.01 mol / L, it is difficult to form a second graphene layer having a small amount of coating amount of the metal catalyst on the first graphene layer, and a dislocation and a grain boundary There is a possibility that the effect of preventing defects becomes insignificant.

In addition, when the concentration of the metal catalyst solution is more than 2.0 mol / L, the non-uniform coating of the metal catalyst may occur, resulting in the synthesis of a non-uniform second graphene layer. Therefore, when the concentration is within the above-mentioned range, the metal catalyst can be uniformly coated on the first graphene layer to improve the electrical conductivity without lowering the permeability even after the second graphene layer is formed, which is effective.

The method may further include forming a second graphene layer on a surface of the first graphene layer on which the graphene growth seed is formed.

The method of forming the second graphene layer is not limited as long as it is a method commonly used for graphene growth in the related art, and may be performed by, for example, chemical vapor deposition (CVD). More preferably, the same conditions as those of the first graphene layer forming method described above, but the present invention is not limited thereto.

The method of manufacturing a graphene laminate structure according to an embodiment of the present invention may further include a step of transferring a final graphene laminate structure having the second graphene layer formed thereon to a substrate. The transfer of the graphene laminate structure can be carried out using any method commonly used in the art without limitation. For example, it can be transferred to glass, quartz, silicon, and SiO ₂ / Si substrates using PDMS, PMMA, heat release tape or the like.

According to another embodiment of the present invention, there can be provided a graphene laminated structure manufactured through the above-described method for producing a graphene laminated structure.

The graphene laminated structure of the present invention may have a transmittance of 97% or more and a sheet resistance of 500 Ω / □ or less.

The graphene laminate structure of the present invention can satisfy the above-described physical properties and can be applied to any one or more electronic device materials selected from a thin film transistor, a memory device, a transparent electrode, a photodetector, a semiconductor device, or a light emitting diode.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of the method for producing a graphene laminated structure of the present invention and a method for measuring a physical property will be described in detail.

Property measurement

1. Scanning electron microscope (SEM) measurement

In order to confirm the surface structure of the graphene laminated structure manufactured according to the present invention, a scanning electron microscope (SEM, Philips, XL-30S FEG Scanning Electron Microscope, accelerating voltage 10 kV, Coater Quorum Q150T ES / 10 mA, coating was used to observe the electrode material. The results are shown in FIG.

2. Measurement of Raman analysis

Raman spectroscopy was performed using Renishaw's RM 1000 invia model. Laser power was measured at 30 mW, laser spot size was 5 μm, and exposure time was 10 seconds.

3. Measurement of permeability

The transmittance was measured using a UV-Vis spectrophotometer (UV-2501pc model of Shimadzu Co., Ltd., ultraviolet-visible spectrophotometer) at a wavelength of 300 nm to 1000 nm with a resolution of 0.1 nm.

4. Sheet Resistance Measurement (Ω / □)

We used CMT-SR1000N of EAST Co., Ltd. and used 4-point probe measurement method.

[Example 1]

Formation of first graphene layer

A copper foil (thickness: 25 탆, Sigma aldrich) was charged into the reactor, and 10 sccm of hydrogen and 1000 sccm of argon were injected and the temperature was raised to 1000 캜 for 45 minutes at 5 Torr. At 1000 캜, 30 sccm of methane is injected as a carbon source, the first graphene is synthesized for 20 minutes, and then cooled to 25 캜.

Formation of graphene growth seed

The first graphene-formed copper foil is immersed in a NiCl ₂ solution (0.2 mol / L in ethanol) as a metal catalyst solution for 30 minutes to form a graphene growth seed by coating the metal catalyst.

CVD process for forming a second graphene layer

The copper foil having the first graphene formed thereon was placed in a reactor, and 10 sccm of hydrogen and 1000 sccm of argon were introduced, and the temperature was elevated to 1000 캜 for 45 minutes at a pressure of 5 Torr. 30 sccm of methane as a carbon source is injected at 1000 캜 and second graphene is synthesized for 20 minutes and then cooled to 25 캜 and transferred to a SiO ₂ / Si substrate to prepare a final graphene laminated structure. The properties are shown in Table 1 below.

[Comparative Example 1]

Formation of first graphene layer

A copper foil (thickness: 25 탆, Sigma aldrich) was charged into the reactor, and 10 sccm of hydrogen and 1000 sccm of argon were injected and the temperature was raised to 1000 캜 for 45 minutes at 5 Torr. At 1000 캜, 30 sccm of methane is injected as a carbon source, the first graphene is synthesized for 20 minutes, and then cooled to 25 캜.

Secondary CVD process

The first graphened copper foil having no metal catalyst coated thereon is placed in a reactor, and 10 sccm of hydrogen and 1000 sccm of argon are introduced, and the temperature is elevated to 1000 캜 for 45 minutes at a pressure of 5 Torr. 30 sccm of methane as a carbon source is injected at 1000 캜 and second graphene is synthesized for 20 minutes and then cooled to 25 캜 and transferred to a SiO ₂ / Si substrate to prepare a final graphene laminated structure. The properties are shown in Table 1 below.

[Table 1]

2 is a scanning electron microscope (SEM) photograph of the surface characteristics of the graphene laminate structure according to one embodiment of the present invention. a) is the surface of the first graphene layer, and b) is the surface on which the first graphene is immersed in the metal catalyst solution to form the metal catalyst graphene growth seed. c) and d) are surfaces on which a second graphene layer is formed on the surface of the first graphene on which the graphene growth seed is formed. It can be confirmed that a hexagonal graphene laminated structure is formed through the graphene growth seed.

3 is a graph illustrating sheet resistance of a graphene laminate structure according to an embodiment of the present invention. Referring to FIG. 3, Example 1 shows a significant decrease in sheet resistance as a result of forming a second graphene, whereas Comparative Example 1 shows a sharp increase in electric conductivity by forming a graphene laminated structure according to the present invention .

FIG. 4 is a graph showing a measurement of transmission of a graphene laminated structure according to an embodiment of the present invention. Referring to FIG. 4, it can be seen that even if the second graphene is formed, the transmittance does not decrease but increases.

This is because, by forming the second graphene, it is possible to form additional conducting paths of the charge carrier by reducing the defects of the graphene and increasing the mobility of the holes, It can be seen that the conductivity is increased.

On the other hand, in Comparative Example 1, since the single-layer graphene is formed even after the secondary CVD process because the metal catalyst coating layer is not present, the permeability is not largely changed, but the sheet resistance is increased due to the increase in the defects of graphene have.

5 is a graph showing Raman measurement results of a graphene laminate structure according to an embodiment of the present invention. The left side is pure graphene measurement, and the right side is a graphene laminate structure according to Embodiment 1 of the present invention. (a) I _2D / I _G map, (b) G-band position map, (c) G-band FWHM map, and (d) I _D / I _G map. As can be seen from FIG. 5, I _2D / I _G shows a characteristic of a single graphene, and I _D / I _G shows a bright region due to a defect in the graphene laminate structure.

FIG. 6 shows electrical characteristics of the graphene laminate structure according to an embodiment of the present invention. It was confirmed that pure graphene and the graphene according to Example 1 had both-pole characteristics characteristic of graphene, and it was confirmed that the inherent characteristics were retained through the process. Also, it can be seen that the Dirac voltage, which is the voltage that the current becomes the smallest due to the p-type doping phenomenon due to the graphene laminate structure, moves to the right while the process is performed.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the above description should not be construed as limiting the scope of the present invention defined by the limits of the following claims.

Claims (10)

a) forming a first graphene layer on the metal thin film;
b) immersing the first graphene in a metal catalyst solution to form a graphene growth seed; And
c) forming a second graphene layer on the surface of the first graphene having the graphene growth seed formed thereon. The method according to claim 1,
Wherein the metal catalyst solution comprises a metal chloride and a solvent,
Wherein the metal chloride is at least one selected from the group consisting of graphene containing at least one of nickel (Ni), copper (Cu), platinum (Pt), palladium (Pd), cobalt (Co), iron (Fe) A method for manufacturing a laminated structure. 3. The method of claim 2,
Wherein the solvent comprises at least one protonic solvent selected from water, (C1-C7) lower alcohols or mixtures thereof. The method according to claim 1,
Wherein the concentration of the metal catalyst solution is 0.01 to 2.0 mol / L. The method according to claim 1,
The first graphene layer in step a) and the second graphene layer in step c) are formed by chemical vapor deposition,
The chemical vapor deposition may be performed by any one or a combination of two or more of high temperature chemical vapor deposition, inductively coupled plasma chemical vapor deposition, low pressure chemical vapor deposition, atmospheric pressure chemical vapor deposition, metal organic chemical vapor deposition and plasma chemical vapor deposition ≪ / RTI > The method according to claim 1,
Wherein the metal thin film is selected from copper foil, nickel foil or an alloy foil of copper and nickel. The method according to claim 1,
Wherein the first graphene layer in step a) and the second graphene layer in step c) are formed by chemical vapor deposition in which a hydrogen: argon: carbon source is injected at 10: 800 to 1200: 20 to 40 sccm, ≪ / RTI >  A graphene laminated structure produced by the method of any one of claims 1 to 7. 9. The method of claim 8,
Wherein the graphene laminate structure has a transmittance of 97% or more and a sheet resistance of 500? /? Or less. 9. The method of claim 8,
The graphene laminate structure may be applied to at least one selected from a thin film transistor, a memory element, a transparent electrode, a photodetector, a semiconductor element, or a light emitting diode.

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