KR20220014161A - Large-area single or multi-layer graphene having a controlled azimuth angle and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a large-area single-layer or multi-layer graphene with a controlled azimuth angle which has a specific crystal orientation and has grown on a single-crystal metal film with a controlled azimuth angle. According to the present invention, provided are a large-area single-layer or multi-layer graphene with a controlled azimuth angle which obtains a large-area single-crystal metal film with a controlled azimuth angle by heat treatment after introducing a single-crystal seed crystal into a polycrystalline metal film by rotating the same at a certain angle and a multi-layer graphene in which the azimuthal angle between graphenes is controlled by stacking the single-layer graphene.

Description

Large-area single or multi-layer graphene having a controlled azimuth angle and manufacturing method thereof

The present invention relates to a large-area single-layer or multi-layer graphene with controlled azimuth and a method for manufacturing the same, and more particularly, to a large-area azimuth-controlled graphene by introducing single crystal seed crystals into a polycrystalline metal film by rotating them at a predetermined angle and then heat-treating them. It relates to a technology capable of obtaining a single-crystal metal film of and using the mono- or multi-layered graphene of a large area with controlled azimuth angles.

Research on single crystallization of various metal films such as copper has been focused on the efficient production of large-area products for applications such as electronic and optical devices and high-quality nano-material composite substrates for the past several years. As a result, a method for efficiently producing single-crystal metal films by heat-treating inexpensive polycrystalline metal substrates using various methods has been developed. Among them, the surface direction of most single-crystal metal films is predictable (for example, (111) for Cu) because it is the most thermodynamically stable and mainly uses a crystal growth method. However, there is a limit in that it is impossible to predict or control how the (111) crystal is rotated and its azimuth angle. In the case of high-quality two-dimensional nanomaterials that grow along the crystal axis of a metal substrate, its properties can vary greatly depending on the azimuth during lamination, so the control of the azimuth is very important.

Currently, a method of inducing crystal growth through heat treatment of existing polycrystalline metal substrates to form single crystals is being developed. In most cases, special equipment, long processing time or a specific metal film are required, and repeatability is poor. However, single crystallization probability and repeatability can be improved by introducing seed crystals into a metal film that has poor repeatability or is not easily single crystallized. The seed crystal can be applied to various single crystallization processes currently developed regardless of the type of heat treatment equipment or the thickness of polycrystalline copper.

On the other hand, a method of making a single crystal metal alloy through directional solidification using seed crystals has been reported. By bringing the seed crystal with known orientation into contact with the mold to manufacture the alloy, the seed crystal is partially melted during heat treatment and the orientation moves to the crystal plane, so that the primary and secondary orientation of the alloy can be controlled, and through this, the mechanical properties can be controlled. can

Recently, when synthesizing double-layer graphene by stacking graphene, studies have been reported to confirm unique electrical properties by controlling the orientation difference between the two graphenes. It is known that the orientation of double-layer graphene induces isolated low-energy bands when stacked with an orientation difference of 1.1°, indicating tunable superconducting and insulating phases.

However, in the case of a single crystal growth method incorporating a conventional seed crystal, the azimuth of a single crystal substrate formed after heat treatment cannot be predicted because seed crystals oriented in an unknown (111) or containing (111) crystals are used. In order for the seed crystal orientation to move through the crystal plane, it must rise to a high temperature near the melting temperature of the alloy. There is a disadvantage in that it costs a lot to prepare a seed tablet with a controlled orientation without it.

In addition, as research on azimuth control in conventional graphene stacking, most of the methods are to peel and stack high-quality graphite having one azimuth angle. In this case, large-area, mass production of multi-layered nanomaterials with controlled azimuth angles is impossible. In addition, when graphene by chemical vapor deposition is used, there is a problem in that the orientation of graphene cannot be known until analysis is completed after synthesis or after lamination.

Therefore, the inventors of the present inventors have found that a single crystal seed crystal is introduced into a polycrystalline metal film by rotation at a certain angle and then heat treated to obtain a single crystal metal film with an azimuth angle controlled, and furthermore, by using this, single-layer graphene with an azimuth angle controlled, and laminated thereof It was discovered that multi-layered graphene can be prepared, and the present invention has been completed.

Patent Literature 1. Korean Patent Publication No. 10-1986788 Patent Document 2. Japanese Laid-Open Patent Publication No. 2004-262684

The present invention has been devised in consideration of the above problems, and an object of the present invention is to obtain a large-area single-crystal metal film with an azimuth angle controlled by heat treatment after introducing a single-crystal seed crystal into a polycrystalline metal film by rotating it at a predetermined angle, and An object of the present invention is to provide a single-layer or multi-layer graphene of a large area with controlled azimuth angle using the graphene and a method for manufacturing the same.

The present invention for achieving the above object provides a single-layer or multi-layered graphene having a specific crystal direction and grown on a single-crystal metal film with a controlled azimuth angle, and a large area with controlled azimuth angle.

The single crystal metal film may include copper (Cu), nickel (Ni), cobalt (Co), iron (Fe), ruthenium (Ru), platinum (Pt), palladium (Pd), gold (Au), silver (Ag), Aluminum (Al), chromium (Cr), magnesium (Mg), manganese (Mn), molybdenum (Mo), rhodium (Rh), silicon (Si), tantalum (Ta), titanium (Ti), tungsten (W) ), uranium (U), vanadium (V), iridium (Ir) and zirconium (Zr) characterized in that any one selected from the group consisting of.

The thickness of the single crystal metal film is characterized in that 15 μm or more.

In addition, the present invention comprises the steps of (I) introducing a single crystal seed crystal having a specific crystal direction to a polycrystalline metal film by rotating it at a predetermined angle and then heat-treating, thereby obtaining a single crystal metal film having an azimuthal angle; and (II) growing graphene on the single-crystal metal film of which the azimuth is controlled.

The heat treatment of step (I) is 100 to 500 sccm, after raising the temperature to 800 to 1200 ° C at a temperature increase rate of 10 to 50 ° C / min in an argon gas atmosphere of less than 2 torr, 100 to 500 sccm, hydrogen gas of 1 torr or more It is characterized in that the isothermal state is maintained for 1 to 4 hours at the elevated temperature under the atmosphere.

The graphene growth in step (II) is performed by maintaining an isothermal state for 10 minutes to 4 hours at 800 to 1200 ° C. do it with

In addition, the present invention provides a multilayer graphene in which the azimuth angle between the graphenes is controlled by stacking the single layer graphene prepared by the above manufacturing method.

According to the present invention, single-crystal seed crystals are introduced into a polycrystalline metal film by rotation at a certain angle and then heat treated to obtain a single-crystal metal film of a large area with an azimuthal angle controlled, and single-layer graphene of a large area with an azimuth angle controlled using this, and By stacking the single-layer graphene, it is possible to provide multilayer graphene in which the azimuthal angle between graphenes is controlled.

1 is an image showing the EBSD (electron backscattering diffraction) and crystal direction of a single crystal copper film heat-treated by introducing a single crystal seed crystal into a polycrystalline copper film according to an embodiment of the present invention.
2 is a (111) standard planar projection view of a single crystal metal film.
3 is an EBSD (electron backscattering diffraction) image and pole view of the interface including a part of a single crystal seed crystal and a part of a single crystallized copper film according to an embodiment of the present invention.
Figure 4 is a pole view showing the introduction by rotating the seed crystal at a certain angle when the single crystal copper film is sliced and used as a seed crystal according to an embodiment of the present invention.
Figure 5 is an image divided into 9 to confirm the crystal direction of the single crystallized copper film according to the embodiment of the present invention.
6 is a pole view showing the crystal direction of the single crystallized copper film divided into 9 in FIG. 5;
7 is an optical electron microscope image divided into 9 after graphene is grown on a single crystal metal film whose azimuth is adjusted according to an embodiment of the present invention.
8 is an image showing the orientation of a single crystallized copper film after introducing a seed crystal having one crystal direction by rotation by 45° and -45° according to an embodiment of the present invention.

In the present invention, the azimuthal angle of the metal film having a specific crystal direction to be single crystallized after heat treatment was adjusted by using a single crystal seed crystal introduction method. In addition, by using this as a growth substrate, it is possible to synthesize graphene with controlled orientation, and through this, the orientation difference during graphene stacking was controlled.

As an embodiment of the present invention, a (111) oriented single crystal copper film with known azimuth is used as a single crystal seed crystal, and single crystallization is induced through heat treatment after contacting the polycrystalline metal film in which single crystallization does not occur in various ways, It was confirmed that the single crystallized metal film had the same crystal direction as the introduced single crystal seed crystal.

In addition, the size of the single crystal seed crystal required for single crystallization is small, so it is possible to adjust the single crystal azimuth that occurs after heat treatment by cutting a large single crystal film whose azimuth has been analyzed and introducing the pieces by rotating the pieces at a certain angle. Controlled or known single-crystal graphene can be synthesized.

Therefore, the present invention provides a single-layer or multi-layer graphene having a specific crystal orientation such as (111) crystal plane orientation and grown on a single-crystal metal film with an azimuthal angle controlled, and having an azimuth-controlled large area.

The single crystal metal film may include copper (Cu), nickel (Ni), cobalt (Co), iron (Fe), ruthenium (Ru), platinum (Pt), palladium (Pd), gold (Au), silver (Ag), Aluminum (Al), chromium (Cr), magnesium (Mg), manganese (Mn), molybdenum (Mo), rhodium (Rh), silicon (Si), tantalum (Ta), titanium (Ti), tungsten (W) ), uranium (U), vanadium (V), iridium (Ir), and may be any one selected from the group consisting of zirconium (Zr).

In addition, the thickness of the single crystal metal film may be 1 to 100 μm, specifically 5 to 50 μm, more specifically 10 to 30 μm. In particular, in the case of a copper film having a thickness of 15 μm or more in the prior art, the single crystallization probability was low even after heat treatment, but the single crystal metal film to which the single crystal seed crystal according to the present invention is introduced has a significantly superior single crystallization probability even when the thickness is 15 μm or more. was confirmed.

In addition, the present invention comprises the steps of (I) introducing a single crystal seed crystal having a specific crystal direction to a polycrystalline metal film by rotating it at a predetermined angle and then heat-treating, thereby obtaining a single crystal metal film having an azimuthal angle; and (II) growing graphene on the single-crystal metal film of which the azimuth is controlled.

The heat treatment of step (I) is 100 to 500 sccm, after raising the temperature to 800 to 1200 ° C at a temperature increase rate of 10 to 50 ° C / min in an argon gas atmosphere of less than 2 torr, 100 to 500 sccm, hydrogen gas of 1 torr or more It may be to maintain an isothermal state for 1 to 4 hours at the elevated temperature under the atmosphere.

The graphene growth in step (II) may be performed by maintaining an isothermal state for 10 minutes to 4 hours at 800 to 1200 ° C. have.

Hereinafter, specific embodiments according to the present invention will be described in detail with the accompanying drawings.

[Example]

As the seed crystal, a copper film with a thickness of 15 μm, which was (111) oriented and single crystallized through heat treatment, was used. The single crystal seed crystal was cut into pieces and introduced by rotating at a predetermined angle on a polycrystalline copper film having a size of 8 x 8 cm and a thickness of 18 μm. Then, after raising the temperature to 1030°C at a temperature increase rate of 30°C/min in an argon gas atmosphere of 100 sccm and 0.42 torr, the heat treatment was performed by maintaining an isothermal state for 2 hours at the elevated temperature in a hydrogen gas atmosphere of 100 sccm and 5 torr. By doing so, a single crystal copper film having an azimuth angle was obtained.

By maintaining the isothermal state at 3 torr, 1020° C. for 20 minutes in an atmosphere of 50 sccm hydrogen gas and 1 sccm methane gas in the single-crystal copper film with the adjusted azimuth angle, graphene is grown on the entire copper area, and the azimuth is controlled large area of single-layer graphene was prepared.

1 shows an EBSD (electron backscattering diffraction) and crystal direction image of a single crystal copper film heat-treated by introducing a single crystal seed crystal into a polycrystalline copper film according to an embodiment of the present invention. As shown in FIG. 1 , it can be confirmed that single crystallization proceeds in the same crystal direction as the single crystal seed crystal during heat treatment by introducing single crystal seed crystals onto the polycrystalline copper film before heat treatment.

In general, one crystal grain has one orientation, which indicates the arrangement of the crystal plane and the crystal direction. The orientation of the metal film can be analyzed through EBSD (electron backscattering diffraction) and pole plots. As can be seen in the (111) standard planar projection of FIG. that can be checked That is, when the metal is a clean single crystal, it has only three (100) poles, and the orientation can be inferred from this.

3 shows an EBSD (electron backscattering diffraction) image and a pole figure of an interface including a part of a single crystal seed crystal and a part of a single crystallized copper film. As can be seen in FIG. 3 , it can be confirmed that both are single crystals based on the interface, and only three (100) poles appear, indicating that the single crystal seed crystal and the single crystallized copper film have the same crystal direction. In addition, as six poles appear in the image of the interface between the seed crystal and the single crystallized copper film, it can be seen that the single crystal seed crystal and the single crystallized copper film have different crystal directions. It can be seen that the three poles in the green circle and the three poles in the red circle each indicate different orientations, and the single crystal seed crystal and the single crystallized copper film have an orientation difference of about 60°.

In the case of single crystallization of a metal film by conventional heat treatment, the oriented crystal plane is predictable because the thermodynamically most stable plane is developed in the single crystal obtained after the heat treatment. However, the crystal misorientation occurring on the same (111) plane was difficult to predict or control. When a single-crystal metal film with a known crystal orientation difference is used as a growth substrate for a two-dimensional nanomaterial such as graphene, the orientation direction of the two-dimensional nanomaterial growing along the crystal axis is predicted and the orientation difference between the nanomaterials affecting the physical properties during lamination It can be easily adjusted.

4 shows that when a single crystal copper film is sliced and used as a seed crystal according to an embodiment of the present invention, the seed crystal is introduced by rotating a certain angle. Since all the fragmented seed crystals have the same orientation difference, the orientation difference can be adjusted after a single crystal by rotating the fragmented seed crystal. That is, the polycrystalline body to be single crystallized has the same direction as the crystal plane direction of the single crystal seed crystal, so by using the above method, the crystal direction of the single crystal metal films produced in different batches can be adjusted to the same or a single crystal metal film with a desired orientation difference can be produced. have.

5 is an image divided into 9 to confirm the crystal direction of the single crystallized copper film according to an embodiment of the present invention, and FIG. 6 is a pole view showing the crystal direction of the single crystallized copper film divided into 9 in FIG. As shown, it can be seen that all 9 zones have three (100) poles at the same position as the seed well. This means that the single crystal seed crystal and the single crystallized copper film have the same crystal direction, suggesting that the crystal direction of the single crystallized copper film can be controlled when the copper film is single crystallized through the introduction of the single crystal seed crystal.

On the other hand, when synthesizing graphene by a chemical vapor deposition (CVD) method, the growth orientation of graphene is affected by the crystal direction of the copper substrate. Therefore, by adjusting the crystal direction of the single crystal copper substrate in the same manner as described above, the orientation of graphene during graphene growth can also be controlled.

7 shows an optical electron microscope image divided into 9 after growing graphene on a single crystal metal film whose azimuth is controlled according to an embodiment of the present invention. It can be confirmed that they are the same.

As described above, it was confirmed that the crystal direction follows the crystal direction of the single crystal seed crystal during single crystallization of the polycrystalline copper film. If controlled, a single crystal copper substrate having a specific crystal orientation can be obtained, and single crystal graphene having a specific orientation can be synthesized through this.

8 shows an image showing the orientation of a single crystallized copper film after introducing a seed crystal having a single crystal direction by rotation of 45° and -45° according to an embodiment of the present invention, one crystal direction In the case of single crystallization after introduction by rotating the introduction angle by 45° and -45° respectively, the orientation of the single crystallized copper film also varies by 45° and -45° along the seed crystal. confirmed that. Through this, it is possible to synthesize large-area graphene having an orientation that is misaligned by a specific angle with respect to the orientation of graphene, which is a reference when synthesizing graphene by the above method.

According to recent research results, when single-crystal graphene is stacked to make double-layer graphene, it has been reported that the electrical properties vary greatly depending on the orientation difference between the two stacked graphenes, and the orientation between the two graphenes is at a specific angle (1.1 °, so-called magic angle) is known to exhibit superconductivity. Therefore, through the above method, the crystal direction of the copper substrate is controlled and the orientation of graphene can be freely controlled when synthesizing graphene, and accordingly, the production and stacking of large-area graphene with a specific angle difference is also possible.

Therefore, according to the present invention, it is also possible to provide multilayer graphene in which the azimuthal angle between graphenes is controlled by stacking single-layer graphene prepared in the same manner as in the embodiment of the present invention.

Claims (7)

A single-layer or multi-layer graphene of a large area with controlled azimuth, grown on a single-crystal metal film with a specific crystal orientation and controlled azimuth. According to claim 1,
The single crystal metal film is copper (Cu), nickel (Ni), cobalt (Co), iron (Fe), ruthenium (Ru), platinum (Pt), palladium (Pd), gold (Au), silver (Ag), Aluminum (Al), chromium (Cr), magnesium (Mg), manganese (Mn), molybdenum (Mo), rhodium (Rh), silicon (Si), tantalum (Ta), titanium (Ti), tungsten (W) ), uranium (U), vanadium (V), iridium (Ir) and zirconium (Zr), characterized in that any one selected from the group consisting of a large-area single-layer or multi-layer graphene with controlled azimuth angle. According to claim 1,
The single- or multi-layered graphene of a large area with controlled azimuth, characterized in that the thickness of the single-crystal metal film is 15 μm or more. (I) obtaining a single-crystal metal film having an azimuth angle controlled by heat treatment after introducing a single-crystal seed crystal having a specific crystal direction to the polycrystalline metal film by rotating it at a predetermined angle; and
(II) growing graphene on the single-crystal metal film of which the azimuth angle is adjusted; 5. The method of claim 4,
The heat treatment of step (I) is 100 to 500 sccm, after raising the temperature to 800 to 1200 ° C at a temperature increase rate of 10 to 50 ° C / min in an argon gas atmosphere of less than 2 torr, 100 to 500 sccm, hydrogen gas of 1 torr or more A method for producing single-layer graphene of a large area with controlled azimuth, characterized in that the isothermal state is maintained for 1 to 4 hours at the elevated temperature in an atmosphere. 5. The method of claim 4,
The graphene growth in step (II) is performed by maintaining an isothermal state for 10 minutes to 4 hours at 800 to 1200 ° C. A method for producing single-layer graphene of a large area with controlled azimuth. Multilayer graphene in which the azimuth angle between graphenes is controlled by stacking single-layer graphene prepared by the manufacturing method according to claim 4 .

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