Preparation method of large-area twin-crystal-containing single crystal copper foil

Abstract

The invention discloses a preparation method of a large-area twin-crystal-containing single crystal copper foil, which comprises the following steps of: rotating the copper foil along the rolling direction, curling and placing the copper foil in a hollow pipe, enabling the rolling direction of the copper foil to form a certain angle with the pipe diameter direction, and then placing the hollow pipe with a sample into a heat treatment furnace containing a reducing atmosphere for annealing treatment to obtain the twin-crystal-containing single crystal copper foil. And finally performing air cooling. According to the preparation method, the single crystal copper foil with the controllable area reaching the centimeter level or above can be prepared according to needs through the annealing mode of combining curling with rotation, the single crystal copper foil can be directly used for follow-up two-dimensional material growth, and the preparation method has the advantages of being low in cost, easy to implement, capable of achieving batch production and the like and has good industrial application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, and in particular to a method for preparing a large-area single crystal copper foil containing twins. Background Art

[0002] Copper foil is commonly used as a metal substrate for preparing graphene and other two-dimensional materials by chemical vapor deposition due to its excellent catalytic properties. The microstructure and orientation of copper foil have an important influence on the quality of the prepared graphene. In the past, it was believed that single-crystalline copper foil with a large area and uniform orientation (such as Cu (111)) is more conducive to the preparation of large-sized and high-quality single-layer graphene. However, the preparation of single-crystalline copper foil usually requires long-term annealing treatment at high temperatures exceeding 1000°C, and the preliminary treatment process is complicated, which makes the entire process inefficient. In addition, copper is prone to form annealing twins that are difficult to completely eliminate during the annealing process, and often requires long-term annealing at ultra-high temperatures close to the melting point.

[0003] Recent studies have found that on some single-crystal copper foil substrates with suitable surface orientation and twins, when two-dimensional materials are prepared by CVD method, the two-dimensional crystal nuclei formed in the matrix area and the twin area can also be seamlessly spliced ​​to form high-quality two-dimensional materials. It shows that this single-crystal copper foil substrate containing twins can also be used for epitaxial growth of single-crystal two-dimensional materials. Therefore, the preparation of copper foil substrates containing twins is of great significance for the preparation of two-dimensional materials such as graphene, boron nitride, etc. And because twins are very common in copper foil after annealing, it can be prepared without focusing on eliminating twins, which helps to reduce the cost of substrate preparation and provides the possibility for large-scale and low-cost preparation of single-crystal two-dimensional materials. However, the distribution of twins is messy and difficult to control. At present, the research on twin substrates is still in its infancy, and its preparation method is limited, requiring further research and development. Therefore, the purpose of the present invention is to provide a stable, fast and convenient large-area single-crystal copper foil preparation method containing twins, and the prepared single-crystal copper foil substrate can be used for the growth of two-dimensional materials.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a large-area single-crystal copper foil containing twins in view of the above-mentioned problems. The present invention rotates the copper foil along the rolling direction and curls it and places it in a hollow cylindrical hollow tube. Then, the hollow tube containing the copper foil is placed in a reducing atmosphere for reduction annealing, so as to obtain a large-area single-crystal copper foil containing twins, thereby overcoming the shortcomings of the prior art.

[0006] The technical solution adopted by the present invention is as follows: a method for preparing a large-area twinned single crystal copper foil, wherein the copper foil is rotated and curled along the rolling direction and placed in a hollow tube, so that a certain angle is formed between the rolling direction of the copper foil and the tube diameter direction, and then placed together with the hollow tube in a heat treatment furnace containing a reducing atmosphere for annealing treatment, and finally air-cooled to obtain the product.

[0007] Further, the copper foil is rotated 0-180° along the rolling direction, for example, 0, 10°, 30°, 45°, 60°, 90°, 120°, 150°, 180°, etc. Preferably, the copper foil is rotated 0-90° along the rolling direction, more preferably 0-45°.

[0008] Furthermore, the inner diameter of the hollow tube is preferably 80-260 mm, for example, 80 mm, 100 mm, 120 mm, 150 mm, 200 mm, 250 mm, 260 mm, etc.

[0009] Furthermore, the hollow tube is made of heat-resistant materials such as quartz or alumina.

[0010] Furthermore, the copper foil used is commercial polycrystalline copper foil.

[0011] Furthermore, the reducing atmosphere is a mixed atmosphere of Ar and H2, wherein the volume fraction of H2 is 5-40%, for example, it can be 5%, 8%, 10%, 20%, 40%, etc., the gas flow rate is 20-100sccm, for example, it can be 20sccm, 40sccm, 60sccm, 80sccm, 100sccm, etc., and the gas flow rate of Ar is 300-700sccm, for example, it can be 300sccm, 400sccm, 500sccm, 600sccm, 700sccm, etc.

[0012] Further, the process parameters of the annealing treatment are: annealing temperature of 600-1100°C, for example, it can be 600°C, 800°C, 900°C, 1000°C, 1050°C, 1100°C, etc., annealing holding time is 10min-24h, for example, it can be 10min, 30min, 60min, 1h, 5h, 12h, 24h, etc., and the pressure during annealing is 0.1Pa-101.325kPa, for example, it can be 0.1Pa, 10Pa, 100Pa, 1000Pa, 101.325kPa, etc.

[0013] Preferably, the process parameters of the annealing treatment are: annealing temperature is 1040° C., annealing holding time is 60 min, and annealing pressure is 101.325 kPa.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0015] 1. The present invention can use commercial polycrystalline copper foil, and in the early stage, the copper foil only needs to be simply rotated and cut as needed, without complicated mechanical and polishing treatment, and the early stage treatment is simple;

[0016] 2. The present invention effectively reduces the preparation cost through simple preliminary treatment, and the preparation process is also simple and economical, and can be completed by only conventional atmosphere annealing, which is low in cost and simple and easy to implement;

[0017] 3. The preparation method of the present invention can effectively control the size of single crystals, and the prepared single crystal substrate can be directly used for the growth of two-dimensional materials, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a flowchart of rapid preparation of large-area single-crystal copper foil containing twins; wherein, Figure (a) is a schematic diagram of a 0-90° rotation method of the copper foil, Figure (b) is a schematic diagram of a copper foil curling method, and Figure (c) is a schematic diagram of a copper foil annealing method;

[0019] Figure 2 The single crystal copper foil obtained by Example 1 of the present invention with a rotation of 0° and a curling diameter of 80 mm;

[0020] Figure 3 The single crystal copper foil obtained by rotating 45° and curling with a diameter of 80 mm in Example 2 of the present invention;

[0021] Figure 4 The single crystal copper foil obtained by rotating 45° and curling with a diameter of 180 mm in Example 3 of the present invention;

[0022] Figure 5 It is the single crystal copper foil obtained by rotating 45° and having a curling diameter of 260 mm in Example 4 of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] Example 1

[0026] A method for preparing a single crystal copper foil substrate suitable for growing two-dimensional materials such as graphene and boron nitride, such as Figure 1 As shown, the following steps are included:

[0027] S1, rotating the commercial polycrystalline copper foil along the rolling direction so that the rolling direction is 0° with the tube diameter direction during curling, and then curling it in a quartz tube with a diameter of 80 mm;

[0028] S2. Place the quartz tube with the copper foil in a heating furnace, anneal at 1040°C for 60 min (excluding 60 min heating) in an Ar and H2 atmosphere, with an annealing pressure of 101.325 kPa, an Ar flow rate of 500 sccm, and a H2 flow rate of 40 sccm, and then air cool to room temperature and take out. Figure 2 As shown in the figure, it can be seen that the single crystal copper foil is evenly distributed with alternating twin boundaries. The twin boundaries in the same direction are parallel, and the twin boundaries in different directions are at the same angle, but there is no grain boundary separation between the twin boundaries in the two directions, and the maximum width can reach 4cm. This shows that a 4×5cm 2 Single crystal copper foil substrate with large area of ​​twins.

[0029] Example 2

[0030] A method for preparing a single crystal copper foil substrate suitable for growing two-dimensional materials such as graphene and boron nitride, such as Figure 1 As shown, the following steps are included:

[0031] S1, the commercial polycrystalline copper foil is rotated along the rolling direction so that the rolling direction is 45° with the tube diameter direction during curling, and then curled into a tube with a diameter of 80 mm, and the thickness of the quartz tube is 3 mm;

[0032] S2. Place the quartz tube with the copper foil in a heating furnace, anneal at 1040°C for 60 min (excluding 60 min heating) in an Ar and H2 atmosphere, with an annealing pressure of 101.325 kPa, an Ar flow rate of 500 sccm, and a H2 flow rate of 40 sccm, and then air cool to room temperature and take out. Figure 3 As shown in the figure, it can be seen that the single crystal copper foil is evenly distributed with "straight" twin boundaries, and the distribution direction of the twin boundaries is relatively consistent throughout the entire length of the sample, reaching 10 cm. A 3×10 cm 2 Single crystal copper foil substrate with large area of ​​twins.

[0033] Example 3

[0034] A method for preparing a single crystal copper foil substrate suitable for growing two-dimensional materials such as graphene and boron nitride, such as Figure 1 As shown, the following steps are included:

[0035] S1, rotating the commercial polycrystalline copper foil along the rolling direction so that the rolling direction is 45° with the tube diameter direction during curling, and then curling it in a quartz tube with a diameter of 180 mm;

[0036] S2. Place the quartz tube with the copper foil in a heating furnace, anneal at 1040°C for 60 min (excluding 60 min heating) in an Ar and H2 atmosphere, with an annealing pressure of 101.325 kPa, an Ar flow rate of 500 sccm, and a H2 flow rate of 40 sccm, and then air cool to room temperature and take out. Figure 4 As shown in the figure, it can be seen that the twin boundaries in the single crystal copper foil are parallel to each other in the same direction, and the grain length reaches 20cm. A single crystal copper foil with a large area of ​​twins is obtained, that is, the area is 3×20cm 2 and 5×10cm 2 Single crystal copper foil substrate.

[0037] Example 4

[0038] A method for preparing a single crystal copper foil substrate suitable for growing two-dimensional materials such as graphene and boron nitride, such as Figure 1 As shown, the following steps are included:

[0039] S1, rotating the commercial polycrystalline copper foil along the rolling direction so that the rolling direction is 45° with the tube diameter direction during curling, and then curling it in a quartz tube with a diameter of 260 mm;

[0040] S2. Place the quartz tube with the copper foil in a heating furnace, anneal at 1040°C for 60 min (excluding 60 min heating) in an Ar and H2 atmosphere, with an annealing pressure of 101.325 kPa, an Ar flow rate of 500 sccm, and a H2 flow rate of 40 sccm, and then air cool to room temperature and take out. Figure 5 As shown in the figure, it can be seen that the straight twin boundaries with relatively consistent directions are evenly distributed on the single crystal copper foil and run through the entire sample length of 15 cm, obtaining a 4×15 cm 2 Single crystal copper foil substrate with large area of ​​twins.

[0041] Through the above examples, the single crystal area can be directly controlled by changing the curling diameter, and a larger curling diameter will correspond to a larger area single crystal copper foil. At the same time, due to the limitation of experimental equipment in the examples, it is impossible to prepare single crystals with larger lengths. Those skilled in the art can use the present invention to improve the experimental conditions to prepare single crystal copper foils with larger areas.

[0042] Comparative Example 1

[0043] Comparative Example 1 is the same as Example 1, except that Comparative Example 1 is not curled, but is directly annealed after being rotated by the same angle.

[0044] Experimental results: A single crystal copper foil containing twins in a large area was obtained, but the distribution of the twins was relatively disordered, and the orientation of some twin structures was disordered and not uniform. The obtained single crystal copper foil was not suitable for use as a substrate for the growth of two-dimensional materials.

[0045] Comparative Example 2

[0046] Comparative Example 2 is the same as Example 2, except that Comparative Example 2 is not rotated, but is directly curled in a tube with a diameter of 80 mm and then annealed.

[0047] Experimental results: Similar to the experimental results of Comparative Example 1, a single crystal copper foil containing twins in a large area was obtained, but the distribution of the twins was relatively disordered, and the orientation of some twin structures was disordered and not uniform. The obtained single crystal copper foil was not suitable for use as a substrate for the growth of two-dimensional materials.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a large-area single-crystal copper foil containing twins, characterized in that: The copper foil is rotated and curled along the rolling direction and placed in a hollow tube so that there is a certain angle between the rolling direction of the copper foil and the tube diameter direction. Then, the copper foil is placed in a heat treatment furnace containing a reducing atmosphere together with the hollow tube for annealing, and finally air-cooled.

2. The preparation method according to claim 1, characterized in that The copper foil is rotated 0-180° along the rolling direction.

3. The preparation method according to claim 1, characterized in that: The inner diameter of the hollow tube is 80-260mm.

4. The preparation method according to claim 5, characterized in that The hollow tube is made of quartz or alumina.

5. The preparation method according to any one of claims 1, characterized in that: The copper foil used is commercial polycrystalline copper foil.

6. The preparation method according to claim 1, characterized in that: The reducing atmosphere is a mixed atmosphere of Ar and H2, wherein the volume fraction of H2 is 5-40%, the gas flow rate is 20-100 sccm, and the gas flow rate of Ar is 300-700 sccm.

7. The preparation method according to claim 1, characterized in that: The process parameters of the annealing treatment are: annealing temperature is 600-1100°C, annealing holding time is 10min-24h, and pressure during annealing is 0.1Pa-101.325kPa.

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