Graphene film and preparation method and preparation device thereof

Abstract

The application discloses a graphene film and a preparation method and a preparation device thereof. The preparation device comprises a carrier for placing a substrate and a correction plate arranged above the carrier, and an angle θ between the correction plate and the carrier along a flow direction of a carbon source gas is adjustable. By arranging the correction plate with a variable included angle between the carrier in the vapor deposition, the application can solve the problem of non-uniformity caused by the size growth of the substrate along the flow direction in the process of scale-up production, and realizes the preparation of a large-size graphene film with high quality and high uniformity.

Description

Technical Field

[0001] This invention belongs to the field of carbon material preparation, specifically relating to graphene films and their preparation methods and apparatus. Background Technology

[0002] As a material with excellent physicochemical properties, achieving high-quality and uniform growth of graphene is a prerequisite for its large-scale application. To address the growth problem of graphene, existing patents have achieved high-quality and high-uniformity growth by constructing confined spaces. Current methods for constructing confined spaces include: placing a carrier in a high-temperature resistant mold with a central groove and then covering it with a cover sheet; or bending the carrier to form a closed cavity.

[0003] However, constructing a confined space by adding an additional carrier is only suitable for the preparation of small-sized graphene films at the laboratory level. As the growth size increases, gas mass transfer becomes problematic, and the accumulation of fragmented active species leads to a decrease in uniformity, ultimately resulting in uneven graphene growth. Constructing a confined space by rolling up the carrier requires high flexibility, and the purpose of constructing a confined space by rolling is to achieve the preparation of bilayer or trilayer graphene, which is not suitable for the high-quality and high-uniform preparation of multilayer graphene.

[0004] Therefore, the preparation of large-sized and highly uniform graphene films is an urgent problem to be solved. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a graphene film, its preparation method, and its preparation apparatus.

[0006] One aspect of the present invention provides a vapor deposition apparatus, including a carrier for placing a substrate and a straightening plate disposed above the carrier, wherein the angle θ between the straightening plate and the carrier along the flow direction of the carbon source gas is adjustable.

[0007] According to one embodiment of the present invention, the projection of the corrective plate in the vertical direction completely covers the carrier.

[0008] According to another embodiment of the present invention, both the carrier and the correction plate are flat, and the extension direction of the carrier is parallel to the flow direction of the carbon source gas.

[0009] According to another embodiment of the present invention, the distance between the correction plate and the carrier is adjustable.

[0010] According to one embodiment of the present invention, the maximum distance between the correction plate and the base is less than or equal to 1 cm.

[0011] According to another embodiment of the present invention, the correction plate is a metal plate, a quartz plate, an alumina plate, or a graphite plate.

[0012] According to another embodiment of the present invention, the length of the carrier along the direction of carbon source gas flow is ≥10cm.

[0013] Another aspect of the present invention provides a method for preparing a graphene film, comprising: growing a graphene film on a substrate by chemical vapor deposition, wherein a correction plate is disposed above the substrate, the correction plate and the substrate forming a certain angle θ along the flow direction of the carbon source gas; θ is positive when the opening between the correction plate and the substrate gradually increases along the flow direction of the carbon source gas, and θ is negative when the opening between the correction plate and the substrate gradually decreases along the flow direction of the carbon source gas, wherein the sign of the angle θ is determined by the cracking energy barrier of the carbon source gas.

[0014] According to one embodiment of the present invention, when the pyrolysis rate of the carbon source gas is consistent with the nucleation and consumption rate of active carbon species, the pyrolysis energy barrier of the carbon source gas is E0; when the pyrolysis energy barrier of the carbon source gas is E... a When E > E0, the angle θ is positive, meaning the opening between the corrector plate and the substrate gradually increases along the flow direction of the carbon source gas; when the cracking energy barrier E of the carbon source gas... a When <E0, the angle θ is negative, that is, the opening between the correction plate and the substrate gradually decreases along the flow direction of the carbon source gas.

[0015] According to another embodiment of the present invention, the maximum distance between the correction plate and the substrate is less than or equal to 1 cm.

[0016] According to one embodiment of the present invention, when the carbon source gas is methane, the angle θ is positive; when the carbon source gas is any one of ethylene, acetylene, ethane, propane, ethanol, or acetonitrile, the angle θ is negative.

[0017] According to another embodiment of the present invention, during the vapor deposition growth process, the flow rate of the carbon source gas is 1-6000 sccm, the pressure is 0.1-101325 Pa, and the growth temperature is 750-1100℃.

[0018] Another aspect of the present invention includes graphene prepared by the above-described preparation method.

[0019] This invention solves the problem of non-uniformity caused by the size growth of the substrate along the airflow direction during the scale-up production process by setting a correction plate and carrier with a variable angle in the vapor deposition process, and realizes the preparation of large-size, high-quality and highly uniform graphene films. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a vapor deposition apparatus according to an embodiment of the present invention.

[0021] Figure 2AThis is a schematic diagram showing the relative positions of the carrier, substrate, and correction plate in the vapor deposition system in Example 1.

[0022] Figure 2B This is a photograph of the graphene-glass fiber fabric composite material prepared in Example 1.

[0023] Figure 2C These are Raman spectra of the graphene film prepared in Example 1 at different positions along the direction of carbon source gas flow.

[0024] Figure 2D This is a sheet resistivity distribution diagram of the graphene film prepared in Example 1.

[0025] Figure 3A This is a schematic diagram showing the relative positions of the carrier, substrate, and correction plate in the vapor deposition system in Example 2.

[0026] Figure 3B This is a photograph of the graphene-glass fiber fabric composite material prepared in Example 2.

[0027] Figure 3C These are Raman spectra of the graphene film prepared in Example 2 at different positions along the direction of carbon source gas flow.

[0028] Figure 3D This is a sheet resistivity distribution diagram of the graphene film prepared in Example 2.

[0029] Figure 4A This is a schematic diagram showing the relative positions of the carrier, substrate, and correction plate in the vapor deposition system in Comparative Example 1.

[0030] Figure 4B This is a photograph of the graphene-glass fiber fabric composite material prepared in Comparative Example 1.

[0031] Figure 4C The images show the Raman spectra of the graphene film prepared in Comparative Example 1 at different positions along the direction of carbon source gas flow.

[0032] Figure 4D This is a sheet resistivity distribution diagram of the graphene film prepared in Comparative Example 1. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments.

[0034] The vapor deposition apparatus of the present invention includes a carrier for placing a substrate and a straightening plate disposed above the carrier, wherein the angle θ between the straightening plate and the carrier along the flow direction of the carbon source gas is adjustable.

[0035] Compared to the small-scale graphene film growth in laboratory settings, the size of the substrate increases dramatically in actual production. If conventional chemical vapor deposition (CVD) equipment is used, the concentration of active carbon species along the gas flow direction will vary significantly, ultimately leading to inconsistent graphene film thickness and poor uniformity on the substrate surface. This invention addresses this issue by using a correction plate at an angle to the carrier. By adjusting the angle between the correction plate and the carrier, the uneven thickness of the grown graphene film, caused by the concentration difference of active carbon species varying with length, can be corrected. During CVD, when the decomposition rate of the carbon source gas matches the nucleation and consumption rate of the active carbon species, the concentration of active carbon species in the CVD device does not change with length. However, when the decomposition rate of the carbon source gas exceeds the nucleation and consumption rate, the concentration of active carbon species in the CVD device gradually increases with length, resulting in a graphene film with gradually increasing thickness along the flow direction of the carbon source gas. When the decomposition rate of the carbon source gas is less than the nucleation and consumption rate of active carbon species, the concentration of active carbon species in the CVD device gradually decreases with length. Therefore, the thickness of the resulting graphene film gradually decreases along the flow direction of the carbon source gas. The vapor deposition apparatus of this invention can adjust the angle between the correction plate and the carrier (i.e., the angle between the correction plate and the substrate) based on the relationship between the decomposition rate of the carbon source gas and the nucleation rate of active carbon species. Specifically, when the decomposition rate of the carbon source gas is greater than the nucleation rate of active carbon species, the angle between the correction plate and the substrate is adjusted to be positive, meaning the opening between the correction plate and the substrate gradually increases along the flow direction of the carbon source gas. At this time, because the distance between the correction plate and the substrate gradually increases along the flow direction of the carbon source gas, the free path of the active carbon species gradually increases. Therefore, the frequency of active carbon species colliding with the substrate gradually decreases along the flow direction of the carbon source gas, thereby offsetting the defect of gradually increasing thickness caused by the gradually increasing concentration of active carbon species along the flow direction of the carbon source gas. Conversely, when the cracking rate of the carbon source gas is less than the nucleation rate of the activated carbon species, the angle between the correction plate and the substrate is adjusted to be negative, that is, the opening between the correction plate and the substrate gradually becomes smaller along the flow direction of the carbon source gas. At this time, as the distance between the correction plate and the substrate gradually decreases along the flow direction of the carbon source gas, the free path of the activated carbon species gradually decreases. Therefore, the frequency of activated carbon species colliding with the substrate gradually increases along the flow direction of the carbon source gas, which can offset the defect of the thickness gradually decreasing due to the concentration of activated carbon species gradually decreasing along the flow direction of the carbon source gas.

[0036] Furthermore, the maximum distance between the correction plate and the substrate does not exceed 1 cm. The distance between the correction plate and the substrate is related to the average molecular free path of the carbon source gas, and the difference is not significant for different carbon source gases. When the maximum distance between them exceeds 1 cm, the confinement effect decreases, making it difficult to increase the collision frequency, and therefore the purpose of adjusting the graphene thickness along the flow direction of the carbon source gas cannot be effectively achieved.

[0037] In the vapor deposition apparatus of the present invention, the direction of carbon source gas flow refers to the direction from the gas inlet to the gas outlet of the vapor deposition apparatus.

[0038] Structurally, the angle θ between the straightening plate and the carrier can be adjusted through any suitable configuration. For example, but not limited to, adjusting only the tilt angle of the straightening plate can achieve this adjustment, as can adjusting the tilt angle of the carrier. Of course, simultaneously adjusting the tilt angles of both the straightening plate and the carrier is also feasible. Furthermore, to better match the flow direction of the carbon source gas, the extension direction of the carrier can be set parallel to the flow direction of the carbon source gas, and the angle can be adjusted by adjusting the straightening plate.

[0039] For angle θ, assuming it's along the flow direction of the carbon source gas, the angle is 0° when the straightening plate is parallel to the carrier. The angle is positive when the opening between the straightening plate and the carrier gradually increases, then 0° < θ ≤ 89°, specifically 0.1°, 0.2°, 0.3°, 0.4°, 0.5°, 1°, 5°, 10°, 20°, 30°, etc. The angle is negative when the opening between the straightening plate and the carrier gradually decreases, then -89° ≤ θ < 0°, specifically -0.1°, -0.2°, -0.3°, -0.4°, -0.5°, -1°, -5°, -10°, -20°, -30°, etc.

[0040] The distance between the straightening plate and the carrier in a vapor deposition apparatus is adjustable. Adjusting the distance between the straightening plate and the carrier adjusts the distance between the straightening plate and the substrate. Specifically, the distance between the straightening plate and the substrate is equal to the distance between the straightening plate and the carrier minus the substrate thickness. Structurally, the adjustable distance between the straightening plate and the carrier in a vapor deposition apparatus can be achieved through any suitable arrangement.

[0041] In an optional embodiment, the vertical projection of the carrier completely covers the substrate to grow a large-sized graphene film with better uniformity on the substrate. If the vertical projection of the corrector plate is smaller than the area of ​​the substrate, the graphene film grown on the substrate portion covered by the vertical projection of the corrector plate also has better uniformity. That is, the uniformity of the graphene film can be improved to some extent even if the vertical projection of the corrector plate does not completely cover the substrate. Preferably, the vertical projection of the carrier completely covers the carrier. The carrier and the corrector plate can be flat, or of course, other shapes.

[0042] In optional embodiments, the straightening plate is any one of a metal plate (e.g., a copper plate), a quartz plate, an alumina plate, and a graphite plate. Specifically, the choice of the straightening plate material is related to the substrate material, and the melting point of the straightening plate should be higher than the graphene growth temperature.

[0043] The vapor deposition apparatus of the present invention allows the carrier to have a length of ≥10cm along the direction of carbon source gas flow. In other words, the vapor deposition apparatus of the present invention can produce large-sized and uniformly thick graphene films with lengths of 10cm, 20cm, 40cm, 80cm, 100cm, 200cm, etc.

[0044] The CVD apparatus of the present invention may also include other auxiliary components for realizing vapor deposition growth, such as pumps, pipelines, valves, etc.

[0045] The following is Figure 1 The working process of the CVD apparatus of the present invention will be explained using an example. Those skilled in the art will understand that... Figure 1 The apparatus shown is merely exemplary and is not intended to limit the invention.

[0046] like Figure 1 As shown, the carbon source gas, auxiliary gas (e.g., H2), and carrier gas (e.g., Ar2) enter the tube furnace through ball valve 1. Flow meters are also included on the carbon source gas, auxiliary gas, and carrier gas branches, allowing control of the gas flow rate into the tube furnace. A quartz tube is installed inside the tube, containing a substrate carrier and a straightening plate positioned above the carrier. The angle between the carrier and the straightening plate is adjustable. Depending on the type of carbon source gas used, the angle θ between the straightening plate and the carrier is adjusted to obtain a large-size and uniformly thick graphene film. The specific adjustment method is as described above. The tube furnace outlet connects to two parallel branches. One branch allows the gas inside the tube furnace to be directly discharged through ball valve 2; when this branch is connected, the tube furnace operates under atmospheric pressure deposition. The other branch connects to a vacuum pump via ball valve 3; when this branch is connected, the tube furnace operates under low-pressure deposition.

[0047] Based on the above-mentioned inventive concept, the method for preparing graphene film of the present invention includes: growing graphene film on a substrate by vapor deposition, setting a correction plate above the substrate, the correction plate and the substrate forming a certain angle θ along the flow direction of carbon source gas, the sign of the angle θ being determined by the cracking energy barrier of carbon source gas.

[0048] Wherein, when the pyrolysis rate of the carbon source gas is consistent with the nucleation and consumption rate of active carbon species, the pyrolysis energy barrier of the carbon source gas is E0; when the pyrolysis energy barrier of the carbon source gas is E... a When E > E0, angle θ is positive, meaning the opening between the correction plate and the substrate gradually increases along the flow direction of the carbon source gas; when the cracking energy barrier E of the carbon source gas... a When E < E0, the angle θ is negative, meaning that the opening between the correction plate and the substrate gradually decreases along the flow direction of the carbon source gas; the maximum distance between the correction plate and the substrate is less than or equal to 1 cm.

[0049] The carbon source gas possesses a fixed pyrolysis energy barrier. Under catalytic conditions such as high temperature, the carbon source gas reaches this barrier and pyrolyzes to form active carbon species. These active carbon species collide with the substrate, forming nuclei on the substrate. As the number of collisional nuclei increases, graphene domains gradually grow and assemble to form a graphene film. If the pyrolysis rate of the carbon source gas at all locations on the substrate is consistent with the nucleation and consumption rate of the active carbon species—that is, if the active carbon species obtained from pyrolysis are immediately and completely consumed—then the graphene growth rate at all locations on the substrate will be uniform. However, when the carbon source gas is a carbon source with a high cracking energy barrier (e.g., methane), the carbon source cracks less in the initial stage. As the carbon source gas flows backward, the cracking gradually increases. This invention addresses this by setting the opening of the correction plate along the airflow direction of the carbon source gas to gradually increase, thereby making the concentration of active carbon species obtained from cracking tend to be balanced. When the carbon source gas is a carbon source with a low cracking energy barrier (e.g., ethylene), the carbon source cracks very actively in the initial stage. As the carbon source gas flows backward, the active carbon atoms obtained from cracking gradually decrease. This invention addresses this by setting the opening of the correction plate along the airflow direction of the carbon source gas to gradually decrease, thereby making the concentration of active carbon species obtained from cracking tend to be balanced.

[0050] Specifically, the cracking rate of the carbon source gas is negatively correlated with its cracking energy barrier. Therefore, when the energy barrier corresponding to the cracking rate being equal to the nucleation and consumption rate of active carbon species is set to E0, the cracking energy barrier E of the carbon source gas used will be... a Compared to E0, when E a When E is greater than 0, it indicates that the cracking rate of the carbon source gas is less than the nucleation and consumption rate of active carbon species. In this case, the angle θ between the correction plate and the substrate is positive, which reduces the collision probability of active carbon species along the flow direction of the carbon source gas. This can counteract the defect of gradually increasing thickness caused by the gradually increasing concentration of active carbon species along the flow direction of the carbon source gas, resulting in a graphene film with better uniformity. Conversely, when E... aWhen the value is less than E0, it means that the cracking rate of the carbon source gas is greater than the nucleation and consumption rate of the active carbon species. At this time, the angle θ between the correction plate and the substrate is negative, which can increase the collision probability of the active carbon species along the flow direction of the carbon source gas. This can offset the defect of the thickness gradually decreasing due to the gradual decrease in the concentration of active carbon species along the flow direction of the carbon source gas, and thus obtain a graphene film with better uniformity.

[0051] The angle θ between the straightening plate and the carrier is related to the cracking energy barrier of the carbon source gas. For carbon source gases with a high cracking energy barrier (greater than E0), angle θ is positive; for carbon source gases with a low cracking energy barrier (less than E0), angle θ is negative. The magnitude of the angle θ between the straightening plate and the carrier is related to the heating temperature, the length of the isothermal zone, and the concentration of the carbon source gas in the CVD apparatus. Based on the inventive concept of this invention, those skilled in the art can make specific settings according to the carbon source gas concentration, CVD growth conditions, etc. For example, the longer the isothermal zone, the smaller the angle, in order to achieve the growth of graphene films with good uniformity.

[0052] Specifically, when the carbon source gas is methane, the angle θ is positive. When the carbon source gas is any one of ethylene, acetylene, ethane, propane, ethanol, or acetonitrile, the angle θ is negative.

[0053] The method for growing graphene films by vapor deposition of the present invention can be carried out under normal pressure or under low pressure. During the growth process, the flow rate of the carbon source gas can be 1-6000 sccm, the pressure can be 0.1-101325 Pa, and the growth temperature can be 750-1100℃.

[0054] The method of this invention can be used to prepare large-sized graphene films with more uniform thickness.

[0055] The present invention is further described below through specific examples. However, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention. Unless otherwise specified, the reagents, materials, and instruments used in the following embodiments and comparative examples are commercially available.

[0056] Example 1

[0057] A glass fiber fabric (length × width × thickness = 40 × 5 × 0.01 cm) is provided as a growth substrate and placed in the heating area of ​​a chemical vapor deposition furnace for atmospheric pressure chemical vapor deposition of graphene.

[0058] Place a quartz straightening plate (40×5×0.3cm, length×width×thickness) on the growth substrate, with its front edge 1mm from the substrate, its rear edge 2mm from the substrate, and an angle of 0.14° with the substrate (the opening gradually increases along the direction of the carbon source gas flow). Figure 2A (As shown).

[0059] The chemical vapor deposition furnace was heated under an argon atmosphere with a flow rate of 200 sccm at a heating rate of 20 °C / min. -1 After the system temperature reaches the growth temperature of 1100℃, 20 sccm of methane gas and 60 sccm of hydrogen gas are introduced, and the growth time is 2 hours. After the growth is completed, the methane gas is stopped, and 50 sccm of hydrogen gas and 100 sccm of argon gas are introduced. The chemical vapor deposition furnace is then cooled down to obtain graphene glass fiber fabric.

[0060] Figure 2B The image shows a composite material of graphene and glass fiber fabric. The uniform color of the sample demonstrates the uniform growth of the graphene film along the airflow direction on a macroscopic scale. Figure 2C This is the Raman spectrum of the graphene-glass fiber fabric composite material along the airflow direction. The spectrum at each position exhibits three characteristic peaks, namely the D peak (~1350 cm⁻¹). -1 G peak (~1580cm) -1 ) and 2D peak (~2680cm) -1 The ratio of the intensities of the 2D peak to the G peak in the Raman spectrum (I). 2D / I G The ratio of the intensity of the D peak to the intensity of the G peak (I) D / I G These parameters can be used to evaluate the thickness and defect density of graphene. The Raman spectra show that the relative intensities of the characteristic peaks are consistent along the airflow direction, proving that the prepared graphene has uniform thickness and defect density. Figure 2D This is a surface resistivity distribution diagram of the graphene-glass fiber fabric composite material. As can be seen, the conductivity of this composite material is uniformly distributed.

[0061] Example 2

[0062] A glass fiber fabric (length × width × thickness = 40 × 5 × 0.01 cm) is provided as a growth substrate and placed in the heating area of ​​a chemical vapor deposition furnace for atmospheric pressure chemical vapor deposition of graphene.

[0063] Place a quartz straightening plate (length × width × thickness = 40 × 5 × 0.3 cm) on the growth substrate, with its front edge 4 mm from the substrate and its rear edge 1 mm from the substrate, forming an angle of -0.43° with the substrate (the opening gradually decreases along the direction of the carbon source gas flow). Figure 3A (As shown).

[0064] The chemical vapor deposition furnace was heated under an argon atmosphere with a flow rate of 200 sccm at a heating rate of 20 °C / min. -1After the system temperature reaches the growth temperature of 1100℃, 10 sccm of ethylene gas and 200 sccm of hydrogen gas are introduced, and the growth time is 2 hours. After the growth is completed, the ethylene gas supply is stopped, and 50 sccm of hydrogen gas and 100 sccm of argon gas are introduced. The chemical vapor deposition furnace is then cooled down to obtain graphene glass fiber fabric.

[0065] Figure 3B The image shows a composite material of graphene and glass fiber fabric. The uniform color of the sample demonstrates the uniform growth of the graphene film along the airflow direction on a macroscopic scale. Figure 3C This is the Raman spectrum of the graphene-glass fiber fabric composite material along the airflow direction. The spectrum at each position exhibits three characteristic peaks, namely the D peak (~1350 cm⁻¹). -1 G peak (~1580cm) -1 ) and 2D peak (~2680cm) -1 The ratio of the intensities of the 2D peak to the G peak in the Raman spectrum (I). 2D / I G The ratio of the intensity of the D peak to the intensity of the G peak (I) D / I G These parameters can be used to evaluate the thickness and defect density of graphene. The Raman spectra show that the relative intensities of the characteristic peaks are consistent along the airflow direction, proving that the prepared graphene has uniform thickness and defect density. Figure 3D This is a surface resistivity distribution diagram of the graphene-glass fiber fabric composite material. As can be seen, the conductivity of this composite material is uniformly distributed.

[0066] Comparative Example 1

[0067] A glass fiber fabric (length × width × thickness = 40 × 5 × 0.01 cm) is provided as a growth substrate and placed in the heating zone of a chemical vapor deposition furnace for atmospheric pressure chemical vapor deposition of graphene (e.g., Figure 4A (As shown).

[0068] The chemical vapor deposition furnace was heated under an argon atmosphere with a flow rate of 200 sccm at a heating rate of 20 °C / min. -1 After the system temperature reaches the growth temperature of 1100℃, 20 sccm of methane gas and 60 sccm of hydrogen gas are introduced, and the growth time is 2 hours. After the growth is completed, the methane gas is stopped, and 50 sccm of hydrogen gas and 100 sccm of argon gas are introduced. The chemical vapor deposition furnace is then cooled down to obtain graphene glass fiber fabric.

[0069] Figure 4B The image shows a composite material of graphene and glass fiber fabric. As can be seen, the color of the sample gradually changes from gray to black along the airflow direction, proving that the growth of the graphene film is uneven along the airflow direction on a macroscopic scale. Figure 4CThis is the Raman spectrum of the graphene-glass fiber fabric composite material along the airflow direction. The spectrum at each position exhibits three characteristic peaks, namely the D peak (~1350 cm⁻¹). -1 G peak (~1580cm) -1 ) and 2D peak (~2680cm) -1 The ratio of the intensities of the 2D peak to the G peak in the Raman spectrum (I). 2D / I G The ratio of the intensity of the D peak to the intensity of the G peak (I) D / I G These can be used to evaluate the thickness and defect density of graphene, respectively. As can be seen from the Raman spectroscopy, along the airflow direction, I... 2D / I G I D / I G The thickness of the graphene gradually decreases along the airflow direction, indicating that the thickness and defect density of the prepared graphene are not uniform, and the thickness of the graphene gradually increases along the airflow direction. Figure 4D This is a surface resistivity distribution diagram of the graphene-glass fiber fabric composite material. It can be seen that the conductivity of this composite material gradually increases along the airflow direction and is unevenly distributed.

[0070] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a graphene film, characterized in that, Graphene films are grown on a substrate using vapor deposition. The substrate is placed on a carrier, and a correction plate is placed above the substrate. The correction plate and the substrate form a certain angle θ along the flow direction of the carbon source gas. θ is positive when the opening between the correction plate and the substrate gradually increases along the flow direction of the carbon source gas, and negative when the opening between the correction plate and the substrate gradually decreases along the flow direction of the carbon source gas. The sign of the angle θ is determined by the cracking energy barrier of the carbon source gas. Suppose that when the pyrolysis rate of the carbon source gas is the same as the nucleation and consumption rate of the active carbon species, the pyrolysis energy barrier of the carbon source gas is E0; when the pyrolysis energy barrier of the carbon source gas is E... a When E > E0, the angle θ is positive, meaning the opening between the corrector plate and the substrate gradually increases along the flow direction of the carbon source gas; when the cracking energy barrier E of the carbon source gas... a When <E0, the angle θ is negative, that is, the opening between the correction plate and the substrate gradually decreases along the flow direction of the carbon source gas.

2. The preparation method according to claim 1, characterized in that, The vertical projection of the correction plate completely covers the carrier.

3. The preparation method according to claim 1, characterized in that, Both the carrier and the correction plate are flat, and the extension direction of the carrier is parallel to the flow direction of the carbon source gas.

4. The preparation method according to claim 1, characterized in that, The distance between the correction plate and the carrier is adjustable.

5. The preparation method according to claim 1, characterized in that, The correction plate is a metal plate, quartz plate, alumina plate, or graphite plate.

6. The preparation method according to claim 1, characterized in that, The length of the carrier along the direction of carbon source gas flow is ≥10 cm.

7. The preparation method according to claim 1, characterized in that, The maximum distance between the correction plate and the base is less than or equal to 1 cm.

8. The preparation method according to claim 1, characterized in that, When the carbon source gas is methane, the angle θ is positive; when the carbon source gas is any one of ethylene, acetylene, ethane, propane, ethanol, or acetonitrile, the angle θ is negative.

9. The preparation method according to claim 1, characterized in that, During the vapor deposition growth process, the flow rate of the carbon source gas is 1-6000 sccm, the pressure is 0.1-101325 Pa, and the growth temperature is 750-1100 °C. o C.

10. A graphene film, characterized in that, Prepared by the preparation method according to any one of claims 1-9.

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