CN112435915A

CN112435915A - Preparation method and device of graphene wafer

Info

Publication number: CN112435915A
Application number: CN201910789995.7A
Authority: CN
Inventors: 刘忠范; 姜蓓; 高翾
Original assignee: Beijing Graphene Institute BGI
Current assignee: Beijing Graphene Institute BGI
Priority date: 2019-08-26
Filing date: 2019-08-26
Publication date: 2021-03-02
Anticipated expiration: 2039-08-26
Also published as: CN112435915B

Abstract

An embodiment of the present invention provides a method and device for preparing a graphene wafer. The method includes preparing a graphene thin film on at least one substrate by a chemical vapor deposition process, wherein, during the chemical vapor deposition process, The included angle between the airflow direction and the at least one substrate is 80-100°. The method of an embodiment of the present invention can realize the uniform preparation of wafer-level large-sized graphene films.

Description

Preparation method and device of graphene wafer

Technical Field

The invention relates to preparation of graphene wafers, in particular to a method and a device capable of preparing graphene wafers in batches.

Background

Quartz, sapphire, SiO₂/Si、Si₃N₄The graphene directly grown on the nonmetal substrates is in the fields of optics, electrics, thermology and the likeHas excellent properties. The graphene on the nonmetal substrate has wide application range and can be used as optical devices, gas sensors, buffer layers for material growth and the like. The polycrystalline graphene with the wafer size can be used as a neutral density filter in the field of photography due to linear light absorption of the polycrystalline graphene. Although graphene has potential application directions in many fields, graphene is not really put into practical application, and rational design of a wafer-size transfer-free graphene preparation method is still a difficult challenge. Therefore, the technology focuses on the batch preparation of graphene wafers on non-metallic substrates.

Among the various methods for preparing graphene, only the silicon carbide epitaxy method and the chemical vapor deposition method are suitable for the preparation of wafer-sized graphene. The silicon carbide epitaxial method has extremely high cost and extremely harsh reaction conditions, so that the chemical vapor deposition method is easier to realize the batch preparation of the graphene with the wafer size. In order to obtain the graphene wafer on the nonmetal substrate, the corresponding chemical vapor deposition method can be divided into two methods, namely growing on metal and then transferring to a target substrate, and directly growing on the target substrate. However, the existing transfer process is not suitable for batch preparation of non-metal-based graphene wafers, and therefore, graphene wafers need to be grown on a non-metal substrate by direct chemical vapor deposition.

Disclosure of Invention

The invention mainly aims to provide a preparation method of a graphene wafer, which comprises the step of preparing a graphene film on at least one substrate by adopting a chemical vapor deposition process, wherein in the chemical vapor deposition process, the included angle between the airflow direction and the at least one substrate is 80-100 degrees.

According to an embodiment of the present invention, the at least one substrate is disposed on a carrier, the carrier includes a base and a supporting member disposed on the base, and a plurality of grooves are disposed on the supporting member.

According to an embodiment of the invention, the bottom surface of the base comprises an arc-shaped surface.

According to an embodiment of the present invention, the base includes two brackets, each bracket includes a first surface and a second surface, the first surface is a bottom surface, the second surface is used for connecting with the supporting component, and the first surface and the second surface each include an arc-shaped surface.

According to an embodiment of the present invention, the first surface is arc-shaped, or the middle part of the first surface is arc-shaped, and two ends connected with the middle part are rectangular; the second surface is arc-shaped, and at least one positioning groove for arranging the supporting part is formed in the second surface.

According to an embodiment of the present invention, the positioning groove is an arc-shaped groove.

According to an embodiment of the present invention, the supporting member includes one or more supporting rods, and the supporting rods are provided with the plurality of grooves.

According to an embodiment of the present invention, the plurality of grooves are arranged along a length direction of the support rod, and a distance between two adjacent grooves is 4mm or more.

According to an embodiment of the present invention, the pressure in the chemical vapor deposition process is 500 to 8000 Pa.

The carrier for the batch preparation of the graphene wafers comprises a base and a supporting part arranged on the base, wherein a plurality of grooves are formed in the supporting part.

According to an embodiment of the invention, the base comprises two brackets, the brackets comprise a first surface and a second surface, the first surface is a bottom surface, the second surface is used for connecting with the supporting component, the first surface and the second surface both comprise arc-shaped surfaces, and/or,

the supporting component comprises one or more supporting rods, and the supporting rods are provided with a plurality of grooves.

An embodiment of the invention provides a preparation apparatus of a graphene wafer, which includes the above carrier.

According to the method provided by the embodiment of the invention, the uniform preparation of the wafer-level large-size graphene film can be realized.

Drawings

Fig. 1 is a schematic structural diagram of a batch preparation of graphene wafers in a horizontal chemical vapor deposition system according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a carrier according to an embodiment of the present invention;

FIG. 3 is a schematic structural view of a stent according to an embodiment of the present invention;

fig. 4A is a typical raman spectrum of 30 4-inch graphene wafers prepared in the same batch in example 1 of the present invention;

fig. 4B shows the transmittance mean and distribution of 30 4-inch graphene wafers prepared in the same batch in example 1 of the present invention;

fig. 4C shows the mean sheet resistance and the distribution of 30 4-inch graphene wafers prepared in the same batch in example 1 of the present invention;

FIG. 5 is a graph showing standard deviations of transmittance of graphene wafers prepared in batches according to examples 2-1, 2-2, 2-3, and 2-4 of the present invention;

fig. 6 is a graph illustrating transmittance distribution of graphene wafers prepared in different batches according to example 3 of the present invention;

fig. 7 is a photograph of a graphene neutral density filter prepared and encapsulated in example 5 of the present invention;

fig. 8 is a variation curve of the transmittance of the graphene neutral density filter obtained in example 5 according to the present invention with wavelength;

fig. 9A is a photograph of a graphene wafer sample prepared in example 6;

fig. 9B is a photograph of a sample of a graphene wafer prepared in a comparative example;

fig. 9C is a distribution graph of the sheet resistance of the graphene wafer samples prepared in example 6 and comparative example;

fig. 9D is a graph showing transmittance distribution of the graphene wafer sample prepared in example 6 and comparative example;

fig. 10 is a photograph of a single sheet of the graphene wafer prepared in batch for example 7;

fig. 10A to 10E are raman surface scans of corresponding sample points on the graphene wafer shown in fig. 10;

fig. 11A is a graph of transmittance distribution of a single sample in the graphene wafers prepared in batch in example 7;

fig. 11B is a transmission profile scan of a single sample in the graphene wafers prepared in batch for example 7;

fig. 12A is a surface resistance surface scan of a single sample from a batch of graphene wafers prepared in example 7;

fig. 12B is a histogram of the distribution of sheet resistance for a single sample from the bulk graphene wafer prepared in example 7.

Detailed Description

Exemplary embodiments that embody features and advantages of the invention are described in detail below in the specification. It is to be understood that the invention is capable of other embodiments and that various changes in form and details may be made therein without departing from the scope of the invention and the description and drawings are to be regarded as illustrative in nature and not as restrictive.

Referring to fig. 1, an embodiment of the present invention provides a method for manufacturing a graphene wafer, including manufacturing a graphene film on at least one substrate (substrate 30) by using a chemical vapor deposition process, wherein an included angle between a gas flow direction (gas flow direction) and the at least one substrate is 80 to 100 ° in the chemical vapor deposition process.

In one embodiment, the "gas flow direction" refers to the flow direction of a gas during a chemical vapor deposition process, and the gas may include argon, hydrogen, carbon source precursors, and the like.

In one embodiment, the substrate 30 and the direction of the gas flow during the chemical vapor deposition process are at angles of 82 °, 85 °, 88 °, 90 °, 92 °, 95 °, 98 °, and the like.

In one embodiment, the number of the substrates 30 is one or more, and when the number of the substrates 30 is more than one, one-time batch preparation of the graphene wafer can be realized.

In one embodiment, the substrate 30 is disposed on the carrier 20 such that the angle between the substrate 30 and the airflow direction is maintained at 80-100 °.

In one embodiment, as shown in FIG. 1, the substrate 30 is positioned perpendicular to the direction of the gas flow, such that the surface of the substrate 30 is in direct-face gas flow.

In one embodiment, a plurality of substrates are arranged on a carrier, and a chemical vapor deposition process is adopted to prepare graphene films on the plurality of substrates; the carrier comprises a base and a supporting part arranged on the base, and a plurality of grooves for placing substrates are arranged on the supporting part.

In the invention, the graphene wafer consists of a graphene film and a single-polished or double-polished wafer substrate.

In one embodiment, for a double-polished wafer substrate, the graphene film uniformly covers two surfaces of the substrate, and one surface of the substrate can be removed by plasma cleaning as required, so that single-sided graphene is retained.

As shown in fig. 1, a carrier 20 according to an embodiment of the present invention is suitable for a horizontal chemical vapor deposition system including a quartz tube 10.

In one embodiment, the gas flow direction is parallel to the axis of the quartz tube 10 during the chemical vapor deposition process.

In one embodiment, the carrier 20 includes a base and a supporting member disposed on the base for supporting the substrate 30 such that the substrate 30 can be vertically placed in the quartz tube 10 of the chemical vapor deposition system, i.e., perpendicular to the axial direction (gas flow direction) of the quartz tube 10.

In one embodiment, the base includes an arc bottom surface to match the inner wall of the quartz tube 10, so that the carrier 20 can be stably placed in the quartz tube 10, and simultaneously, the substrate 30 on the carrier 20 can be concentric with the quartz tube 10, and the base of the carrier 20 does not block the airflow and plays a role in stabilizing.

In one embodiment, the position of the substrate 30 in the quartz tube 10 can be changed by adjusting the shape of the susceptor.

As shown in fig. 2 and 3, in one embodiment, the base includes a bracket 21 and a bracket 22, and the bracket 21 and the bracket 22 have the same structure.

In one embodiment, the support 21 includes a first surface 211 and a second surface 212 which are oppositely disposed, the first surface 211 (lower surface) is a bottom surface for directly contacting the quartz tube 10, and the second surface 212 (upper surface) is for contacting the supporting member.

In one embodiment, the first surface 211 comprises an arcuate surface to match the shape of the inner wall of the quartz tube 10.

In an embodiment, the first surface 211 may be an arc surface wholly or partially, that is, the first surface 211 may be an arc wholly, or an arc surface in the middle, and the two ends connected to the middle are rectangular surfaces, or one end connected to the middle is a rectangular surface and the other end is an arc surface.

In an embodiment, the second surface 212 may be an arc-shaped surface wholly or partially, that is, the second surface 212 may be an arc-shaped surface wholly or partially, and may also be an arc-shaped surface in the middle, and both ends connected to the middle are rectangular surfaces, or one end connected to the middle is a rectangular surface and the other end is an arc-shaped surface.

In an embodiment, the second surface 212 is provided with two positioning grooves 212a for disposing the supporting member, and the two positioning grooves 212a are respectively located at two sides of the central portion of the second surface 212.

In one embodiment, the second surface 212 may have a shape substantially the same as the first surface 211, and both have an arc shape, and the center of the arc shape of the second surface 212 is located at the same side as the center of the arc shape of the first surface 211, that is, adjacent to one side of the second surface 212, so that the second surface 212 is located at the inner side of the first surface 211.

In one embodiment, the first surface 211 is parallel to the second surface 212.

In one embodiment, the bracket 21 includes two sides 213 connecting the first surface 211 and the second surface 212, the two sides 213 are disposed in parallel, and the thickness of the bracket 21 is the distance between the two sides 213.

In one embodiment, the

brackets

21 and 22 are arc-shaped, arc-like (a portion of which is arc-shaped) strips or sheets.

In one embodiment, the material of the

supports

21 and 22 may be high temperature resistant quartz, for example, the

supports

21 and 22 may be arc-shaped or arc-like quartz strips or quartz sheets.

In one embodiment, the support member may be one or more support rods 23, preferably two support rods 23.

In one embodiment, the support rod 23 is a rod, preferably a round rod, and the support rod 23 is formed with a plurality of grooves 231, and the plurality of grooves 231 are arranged along the longitudinal direction (axial direction) of the support rod 23.

The number of the grooves 231 is not limited, and may be adjusted according to actual needs, used equipment, conditions, and the like, and the number of the grooves 231 may be 2 to 50, for example, 10, 20, 30, 40, and the like.

In one embodiment, the groove 231 is perpendicular to the axis of the support rod 23.

In one embodiment, the groove 231 is formed on the circumferential surface of the support rod 23, the depth direction of the groove is perpendicular to the axial direction of the support rod 23, and the width of the groove 231 may be slightly larger than the thickness of the substrate 30, so that the substrate 30 can be inserted into the groove 231.

In one embodiment, the groove 231 may have an arc shape to match the shape of the edge portion of the circular substrate 30, so that the substrate 30 can be stably disposed on the carrier 20.

In one embodiment, the plurality of grooves 231 have equal spacing (distance between adjacent grooves), and the spacing may be 4mm or more, for example, 5 to 20mm, and specifically may be 8mm, 10mm, 15mm, 18mm, 25mm, 30mm, and the like.

In one embodiment, one end of the support rod 23 is disposed on the bracket 21, and the other end is disposed on the bracket 22. The support rod 23 may be fixedly connected to the bracket 21 and the bracket 22, or may be directly placed on the surfaces of the bracket 21 and the bracket 22, for example, the support rod 23 may be placed in the positioning groove 212a, and the positioning groove 212a may match with the shape of the support rod 23, such as an arc shape, to achieve a stabilizing effect.

In one embodiment, the grooves on the two support rods 23 are positioned to correspond such that the substrate 30 can be placed perpendicular to the axial direction of the support rods 23.

In one embodiment, the two support rods 23 are disposed in parallel on the support 21 and the support 22, and the distance between the axes of the two support rods 23 is smaller than the diameter of the substrate 30.

In one embodiment, the support rod 23 may be made of quartz, i.e., the support rod 23 is a quartz rod.

The size of the carrier 20 is not limited in the present invention, and can be adjusted according to the actual requirement and the size of the quartz tube 10.

In one embodiment, the length of the carrier 20 is 15cm, the length of the support rod 23 is 15cm, the diameter of the support rod 23 is 12mm, and the thickness of the support 21 and the thickness of the support 22 are both 8 mm.

In one embodiment, referring to fig. 1, the substrates 30 are arranged perpendicular to the gas flow direction within the quartz tube 10, and two carriers 20 may be used simultaneously to load more substrates 30.

In one embodiment, the substrate 30 is selected from sapphire, quartz, SiO₂/Si、Si₃N₄And the like.

In one embodiment, the substrate 30 has a thickness of 0.6 to 1mm, such as 0.7mm, 0.8mm, 0.9mm, etc.

In one embodiment, the carrier 20 may be placed along the direction of its support rods 23 parallel to the axis of the quartz tube 10 such that the substrates 30 on the carrier 20 are perpendicular to the axis of the quartz tube 10 and thus perpendicular to the gas flow direction during the cvd process.

According to the embodiment of the invention, the graphene wafers are prepared in a program-controlled batch manner.

In one embodiment, a batch system is modeled by taking numerical analysis as reference, and the important functions of the heat accumulation effect and the air flow confinement effect in the uniform growth process of graphene are provided by simulating the temperature field and flow field distribution of the system.

In one embodiment, the graphene wafer may be made more uniform by further adjusting parameters in the batch system, such as the substrate pretreatment method, the specific growth process, and the like.

In one embodiment, the growth process may be, for example, a substrate spacing, a growth temperature, a growth pressure, a growth time, a flow rate of a carbon source precursor, or the like.

In one embodiment, before the graphene film is grown, a pretreatment process of air annealing is performed, and the annealing time is 0.5 to 1 hour.

In one embodiment, the graphene film is formed on the substrate 30 by a chemical vapor deposition process.

In the growth process of the graphene film, the forming temperature of the graphene film is 1050-1100 ℃.

In the growth process of the graphene film according to an embodiment of the present invention, the growth time of the graphene film is 1 to 5 hours, for example, 2 hours, 3 hours, 4 hours, and the like.

In the growth process of the graphene film according to an embodiment of the present invention, the flow ratio of the carbon source to the hydrogen gas is (350-750): 500, for example, 380:500, 400:500, 450:500, 500:500, 550:500, 600:500, 650:500, 700:500, and the like.

In the growth process of the graphene film, the pressure of the system is 500-8000 Pa, such as 800Pa, 1000Pa, 2000Pa, 3000Pa, 4000Pa, 5000Pa, 6000Pa, 7000Pa and the like.

The method of one embodiment of the invention can realize the application-oriented uniform preparation of 30-50 2-6 inch graphene wafers.

The graphene wafer prepared by the embodiment of the invention has uniform single wafer and adjustable uniformity among wafers.

The graphene wafer prepared by the embodiment of the invention has a large range of wafer-level layers and uniform crystallization quality.

According to the graphene wafer prepared by the embodiment of the invention, the transmittance fluctuation of each point of the sample is small.

The graphene wafer prepared by the embodiment of the invention has small fluctuation of Raman signals of each point of the sample.

The graphene wafer prepared by the embodiment of the invention has small fluctuation of the surface resistance.

The graphene wafer prepared by the embodiment of the invention has small fluctuation of transmittance, surface resistance, Raman signal and the like of each point of the sample, and fully shows the uniformity of the performance of each point of the graphene.

The following describes a method for preparing a graphene wafer according to an embodiment of the present invention with reference to the accompanying drawings and specific examples. Wherein, the raw materials are all obtained from the market.

Example 1

The transfer-free graphene can be synthesized on a 4-inch wafer substrate in a batch programmable manner by adopting a 6-inch horizontal CVD tube furnace with three temperature zones.

1) Washing or soaking 30 quartz glass wafer substrates (substrates 30) with the thickness of 1mm and double polishing of 4 inches in sequence by using deionized water, ethanol, acetone and deionized water, drying by using high-purity nitrogen and placing on a super clean bench for later use;

2) placing the cleaned substrates 30 in the grooves 231 of the carrier 20, wherein the distance between two adjacent grooves 231 is 5mm, placing one substrate 30 at every other groove 231, and making the distance between the centers of the adjacent substrates 30 be 10mm, and loading two carriers 20;

3) placing two carriers 20 loaded with 30 substrates 30 into a quartz tube 10 of a CVD system, wherein the substrates 30 are vertically placed (vertical to the axial direction of the quartz tube 10), heating to 1050 ℃ in an oxygen atmosphere, and keeping the temperature for 30 min; in the temperature raising and maintaining process, the temperature field in the system is stabilized, and the substrate 30 is subjected to annealing pretreatment.

4) Vacuumizing the CVD system, closing the vacuum pump when the reading of the pressure gauge reaches below 6Pa, and observing the pressure rise rate to check the air tightness of the system; after ensuring that the system has good air tightness, opening a vacuum pump, and introducing argon with the flow of 500 sccm; after the reading of the pressure gauge rises and is stable (about 300Pa), closing argon gas to reduce the pressure of the system to below 6 Pa; repeating the step of introducing argon for 1-2 times to ensure that oxygen in the system is completely discharged;

5) setting the argon flow to be 500sccm and the hydrogen flow to be 500sccm, opening a hydrogen valve, setting the system pressure to be 2kPa, then opening a rotor flow meter, adjusting the ethanol gas flow to be 500sccm, and enabling the direction of the mixed gas flow to be vertical to the substrate 30; and starting timing after the actual pressure of the system reaches a set value, wherein the reaction time is 2 h.

6) And after the reaction is finished, closing the rotameter, and naturally cooling the sample along with the furnace to obtain 30 transfer-free graphene with wafer-level uniformity.

The graphene wafer samples obtained in example 1 have high uniformity. For a large-sized graphene wafer, the uniformity of the large-sized graphene wafer can be generally evaluated by three methods, namely visual or optical microscope observation, raman spectroscopy and surface resistance measurement. For a large-size quartz-based graphene sample, in addition to the two methods, the uniformity of the sample can be represented by a transmittance surface scanning graph by utilizing the high light transmittance of quartz glass and the linear light absorption property of graphene. The raman spectrum, transmittance characterization, and sheet resistance characterization of each sample are shown in fig. 4A, 4B, and 4C. As can be seen from fig. 4A, all samples had a distinct intensity 2D peak with similar full width at half maximum, indicating that the resulting graphene wafers had uniformity of quality. Fig. 4B shows that the average transmittance (single-sided) of each graphene sample falls within the range of 92% to 96%, and the fluctuation within each wafer is small, only 1%. Fig. 4C shows the sheet resistance data for 30 samples, with 81 sample points collected for each sample, and the distribution represented by mean and error bars. The optical/electrical properties of the middle 26 sheets were very consistent, except for the samples (nos. 1, 2, 29, 30) at the front and back ends where the edge effect was present.

Example 2-1

The cleaning process of the substrates 30 was the same as in example 1, and a single carrier 20 was used to control the center-to-center distance between every two adjacent substrates 30 (4-inch quartz glass wafers) to be 5mm, and 30 substrates were placed in total. The process is carried out according to the corresponding steps except that argon is closed in the growth process, and the flow rate of ethanol gas is 530 sccm.

Examples 2 to 2

Other conditions were controlled to be the same as in example 2-1, the distance between the centers of every two adjacent substrates 30 was changed to 10mm, and 15 sheets were placed in total to perform batch preparation of graphene wafers.

Examples 2 to 3

Other conditions were controlled to be the same as in example 2-1, the distance between the centers of every two adjacent substrates 30 was changed to 15mm, and 10 sheets were placed in total to perform batch preparation of graphene wafers.

Examples 2 to 4

Other conditions were controlled to be the same as in example 2-1, the distance between the centers of every two adjacent substrates 30 was changed to 20mm, and 8 sheets were placed in total to perform batch preparation of graphene wafers.

The effect of sample chip spacing on batch uniformity for examples 2-1, 2-2, 2-3, 2-4 is shown in FIG. 5. Where the standard deviation reflects the degree of dispersion of the data from the mean, and is the square root of the variance. The data here is the single-sheet average transmittance for each sheet, from which the standard deviation is calculated, and the level of uniformity for this batch can be seen. Therefore, program control and adjustability of sample uniformity can be achieved by adjusting and controlling the inter-plate distance, and different inter-plate distance parameters are selected according to actual requirements on sample quality and yield.

Example 3

The processes of cleaning, loading and heating the substrate 30 (4-inch quartz glass wafer) were the same as in example 1, except that the growth temperature was 1080 ℃, the flow of argon gas was 0sccm, the flow of hydrogen was 800sccm, the flow of ethanol was 450sccm, the growth time was 4 hours, and the flow of argon gas was 800sccm during the cooling process.

The above experiment was performed 5 times by different operators and the transmittance of the sample was characterized as shown in fig. 6. The results in fig. 6 show that the single-sided transmission data for each batch of samples falls within the range of 88% to 95%, demonstrating that the method is reproducible, with good reproducibility, and that the system is robust.

Example 4

The method comprises the step of growing single-layer graphene in batches by taking a 2-inch c-plane sapphire wafer as a substrate, wherein the single-layer graphene is used as a novel substrate for growing group III nitride.

The sapphire substrate used was single-side polished and had a thickness of 0.6 mm.

The cleaning process of the substrate 30 is the same as in embodiment 1. Using 2 carriers 20, the distance between the centers of every two adjacent substrates 30 is controlled to be 10mm, and 30 substrates are placed in total. The method comprises the following steps of example 1, except that the flow rate of ethanol gas is 550sccm in the growth process, and the reaction time is 2 hours, so that the sapphire smooth surface is covered with 1-2 layers of graphene.

Example 5

A quartz glass wafer with the diameter of 70mm is used as a substrate, and a graphene neutral density optical filter with the transmittance of 25% is prepared in batches and is used for single-lens reflex camera shooting.

The quartz glass wafer used was double polished to a thickness of 1 mm.

The cleaning process of the substrate 30 is the same as in embodiment 1. Using 2 carriers, the distance between the centers of every two adjacent substrates 30 is controlled to be 10mm, and 30 substrates are placed in total. The procedure of example 1 was followed except that the flow rate of ethanol gas during the growth was 750sccm and the reaction time was 2 hours. The obtained sample was packaged as shown in fig. 7, and the actual transmittance was about 25% (fig. 8), and it was used in a highlight photography scene.

Example 6

The other conditions were controlled in the same manner as in example 1, and the pressure in the system was adjusted to be normal pressure to perform the batch preparation of graphene wafers. The specific growth conditions are as follows: argon flow of 800sccm, hydrogen flow of 500sccm, methane flow of 60sccm, and growth time of 5 h.

Example 7

The cleaning process of the substrates 30 was the same as in example 1, and 2 carriers 20 were used, with the distance between the centers of two adjacent substrates 30 (4-inch quartz glass wafers) being controlled to 10mm, and 30 substrates were placed in total. The method is carried out according to the corresponding steps, and the difference is that: the growth temperature is 1080 ℃, the hydrogen flow in the growth process is 800sccm, the argon flow is 800sccm, the ethanol gas flow is 400sccm, and the reaction time is 5 h.

The uniformity of individual pieces in a batch sample can be evaluated by a characterization method such as visual inspection (optical microscope observation), raman surface scanning, transmittance surface scanning, and surface resistance surface scanning. As shown in fig. 10A to 10E, in any sample of example 7 (where the characterization results of the 20 th piece are shown), the contrast was visually uniform, and the intensity ratio of the 2D peak to the G peak was very small in a wide range when raman surface scanning was performed on A, B, C, D, E five sample points in fig. 10 using a five-point sampling method. In fig. 10B, 10C, 10D, and 10E, the length shown on a scale is the same as that in fig. 10A.

The sample is sampled at 81 points according to polar coordinates, and the transmittance and the sheet resistance are characterized, specifically, as shown in fig. 11A to 12B, the transmittance fluctuation of single-sided graphene is only 0.8%, and the corresponding sheet resistance surface scanning graph also shows the uniformity of contrast, thereby proving that the graphene wafer prepared by the method has excellent single-sheet uniformity.

Comparative example

The other conditions were controlled the same as in example 6, except that: the substrate 30 is horizontally placed inside the quartz tube 10 (parallel to the gas flow direction).

Fig. 9A is a photograph of a sample of the graphene wafer obtained in example 6, and fig. 9B is a photograph of a sample of the graphene wafer obtained in a comparative example. The contrast of the sample in fig. 9A was more uniform as can be seen by visual inspection of the contrast. Further, the transmittance and the sheet resistance information at different points on each sample were collected to compare the uniformity of both samples, as shown in fig. 9C and 9D, respectively. The location of the sample points, both selected from a radial direction of relative least uniformity on both samples, for the sample in fig. 9A, the vertical radial direction when placed vertically is selected; for the fig. 9B sample, the points were chosen radially along the direction of gas flow. The position of a sample point collected on the sample of the comparative example, the corresponding transmittance and the corresponding surface resistance are represented by square points; while the samples of example 6 are indicated by dots. The following conclusions can be drawn through comparison: under normal pressure, the graphene wafer prepared by placing the substrate 30 perpendicular to the gas flow direction in example 6 can achieve higher sample uniformity than the graphene wafer prepared by placing the substrate 30 parallel to the gas flow direction in the comparative example.

Unless otherwise defined, all terms used herein have the meanings commonly understood by those skilled in the art.

The described embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the present invention, and those skilled in the art may make various other substitutions, alterations, and modifications within the scope of the present invention, and thus, the present invention is not limited to the above-described embodiments but only by the claims.

Claims

1. a preparation method of graphene wafer, comprises and adopts chemical vapor deposition process to prepare graphene film on at least one substrate, wherein, in the chemical vapor deposition process, airflow direction and described at least one substrate The included angle is 80-100°.

2. The method of claim 1, wherein the at least one substrate is disposed on a carrier, the carrier comprising a base and a support member disposed on the base, the support member being disposed with Multiple grooves.

3. The method of claim 2, wherein the bottom surface of the base comprises an arcuate surface.

4. The method of claim 2, wherein the base includes two brackets, the brackets including a first surface and a second surface, the first surface being a bottom surface, the second surface for interacting with the The supporting parts are connected, and both the first surface and the second surface include arc surfaces.

5. The method according to claim 4, wherein the first surface is in an arc shape, or a middle part of the first surface is in an arc shape, and two ends connected to the middle part are in a rectangle; the second surface is in an arc shape At least one positioning groove for arranging the support member is opened on the second surface.

6. The method of claim 2, wherein the support member comprises one or more support rods, and the plurality of grooves are formed on the support rods.

7 . The method of claim 1 , wherein the pressure during the chemical vapor deposition process is 500-8000 Pa. 8 .

8. A carrier for batch preparation of graphene wafers, comprising a base and a support member arranged on the base, and a plurality of grooves are provided on the support member.

9. The carrier of claim 8, wherein the base includes two brackets, the brackets including a first surface and a second surface, the first surface being a bottom surface, the second surface for interacting with the support members are in contact, the first surface and the second surface both comprise arcuate surfaces, and/or,

The support member includes one or more support rods, and the plurality of grooves are opened on the support rods.

10. A preparation device of graphene wafer, comprising the carrier for batch preparation of graphene wafer according to claim 8 or 9.