A method for in-situ preparation of graphene by magnetron sputtering

Abstract

This invention provides a method for in-situ preparation of large-area graphene layers by magnetron sputtering, comprising the following steps: (1) preparing a p-xylene dimer block target; (2) growing a carbon thin film on a silicon substrate by magnetron sputtering; and (3) graphitizing the carbon thin film to form a graphene thin film by rapid annealing. This invention prepares large-size graphene by in-situ magnetron sputtering, which has the advantages of simple process, low cost, adjustable area, and in-situ preparation avoiding wrinkle formation. This is beneficial for realizing the large-scale application of graphene on silicon-based platforms and can also be extended to other high-temperature resistant rigid or flexible substrate materials (such as SiN). x SiC, AlN x (e.g., ZnO).

Description

Technical Field

[0001] This invention relates to graphene, specifically to a method for in-situ preparation of graphene by magnetron sputtering, which belongs to the field of novel materials. Background Technology

[0002] Graphene, with its unique lattice structure, has become one of the star materials in the scientific community. It is a novel carbon-based material with a two-dimensional honeycomb lattice structure composed of a single layer of tightly packed carbon atoms. Graphene has a large specific surface area, an ultrathin atomic layer thickness of only 0.335 nm, a simple structure, and exhibits the greenhouse quantum Hall effect, good ferromagnetism, and outstanding electrical, optical, mechanical, and thermal properties. It has broad application prospects in the semiconductor industry, photovoltaic industry, lithium-ion batteries, aerospace, and military industries. Methods for preparing graphene films include mechanical exfoliation, graphene oxide reduction, chemical vapor deposition (CVD), epitaxial growth, electrochemical methods, arc methods, and organic synthesis. Among these, graphene prepared by the graphene oxide reduction method is prone to agglomeration and can cause acid and alkali contamination. Currently, the preparation of high-quality, large-size graphene typically involves first growing graphene on a copper substrate using chemical vapor deposition (CVD), and then transferring it to a SiO2 / Si substrate via a transfer method. However, this method yields graphene with a small area, is prone to wrinkling or breakage, presents certain operational difficulties, and is costly. In summary, current methods for preparing graphene have limitations. Therefore, it is essential to find a simple, low-cost method with minimal wrinkling and breakage to achieve the industrialization of graphene production. Summary of the Invention

[0003] To address the issues of wrinkles and damage that easily occur during the CVD graphene transfer process, this invention provides a simpler in-situ method for preparing large-area graphene layers. The key is to grow a carbon thin film on a silicon substrate using magnetron sputtering, followed by rapid annealing to graphitize the carbon film and form a graphene film. Its advantages include adjustable area, in-situ preparation avoiding wrinkles or damage, and simple operation, facilitating the large-scale application of graphene on silicon-based platforms.

[0004] To achieve the objective of this invention, a method for in-situ preparation of graphene by magnetron sputtering is provided, comprising the following steps:

[0005] (1) Preparation of target material

[0006] p-xylene dimer blocks were selected as the carbon source, and the p-xylene dimer powder was compressed into cake-shaped p-xylene dimer blocks using a powder tableting machine. First, the p-xylene dimer block powder was loaded into the tableting machine mold. After the mold was installed, pressure was applied to compact the powder. Then, the air was released and the mold was removed to obtain cake-shaped p-xylene dimer block target material.

[0007] (2) Cleaning the substrate

[0008] The SiO2 / Si substrate was ultrasonically cleaned for 10-30 minutes in acetone solution, deionized water, and anhydrous ethanol, respectively, to remove organic and inorganic particles and dust particles from the substrate surface, and then dried with nitrogen gas for later use.

[0009] (3) Coating

[0010] The substrate was placed in the chamber of the high-vacuum multi-target magnetron sputtering coating system. Vacuuming was initiated until the base pressure was reached. Argon gas was then introduced, and the gas flow controller was adjusted to maintain the pressure at 3–5 Pa. The radio frequency power supply was turned on, and the sputtering power was adjusted to 60–120 W (refer to “Yang Ling, Pan Yingjun, Zheng Shien, et al. Study on the structure and process parameters of magnetron sputtered titanium films on graphite surfaces”). Sputtering was performed for 5–30 minutes to prepare a p-xylene dimer film on the substrate. Finally, the gas was evacuated, and the sample was removed.

[0011] (4) High-temperature annealing graphitizes p-xylene polymers to form graphene.

[0012] Place the previously prepared sample into a rapid annealing furnace, set a heating curve to raise the temperature to 800-1200℃ (refer to "Bai Qingshun, Guo Wanmin, He Chenghui, et al. Study on process parameters for chemical vapor deposition preparation of high-quality graphene"), hold for 1-2 minutes, and remove the sample after natural cooling.

[0013] The beneficial effects of this invention are:

[0014] Compared to CVD methods for preparing graphene, magnetron sputtering in-situ preparation is a simpler method that does not require transfer to a SiO2 / Si substrate, thus solving the problem of wrinkles or damage that easily occur during the transfer of graphene films. Moreover, the size of the graphene is adjustable.

[0015] Compared to the graphene reduction method for preparing graphene, this invention does not cause acid or alkali pollution and solves the problem of graphene agglomeration. Attached Figure Description

[0016] Figure 1 The image shows the OM diagram of graphene prepared by the method of this invention. It can be clearly seen that the graphene has a uniform thickness and a smooth surface.

[0017] Figure 2 The AFM of graphene prepared by the method of this invention was used to obtain graphene with different sputtering powers and sputtering times.

[0018] Figure 3 The image shows the XRD pattern of graphene prepared by the method of this invention.

[0019] Figure 4The image shows the Raman spectrum of graphene prepared by the method of this invention, at 1582 cm⁻¹. -1 The G peak of graphene appears at 1350 cm⁻¹. -1 The D-surface graphene exhibits defects.

[0020] The above experimental results are consistent with those of graphene films prepared by other methods. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the embodiments.

[0022] Chemical reagents and experimental instruments used in this invention:

[0023] p-xylene dimer powder, acetone, anhydrous ethanol, and silicon wafers were purchased from Sinopharm Chemical Reagent Co., Ltd. (purity was analytical grade). Deionized water was obtained by filtration using a pure water system. The equipment included a high-vacuum multi-target magnetron sputtering coating system, a rapid annealing furnace, a powder tablet press, and a pure water system (Thin Film Physics Research Laboratory, Department of Physics, University of Science and Technology of China).

[0024] Example 1:

[0025] (1) Preparation of target material

[0026] p-xylene dimer blocks were selected as the carbon source, and the p-xylene dimer powder was compressed into cake-shaped p-xylene dimer blocks using a powder tableting machine. First, the p-xylene dimer block powder was loaded into a tableting machine mold with a diameter of 60 mm and compacted. Then, the mold was installed and a pressure of 10 MPa was applied. After releasing the air, the mold was removed to obtain p-xylene dimer blocks with a diameter of 60*5 mm.

[0027] (2) Cleaning the substrate

[0028] The SiO2 / Si substrate was ultrasonically cleaned for 10 min each with acetone solution, deionized water, and anhydrous ethanol. The cleaned substrate was then dried with nitrogen gas for later use.

[0029] (3) Coating

[0030] The cleaned SiO2 / Si substrate was fixed on the sample stage inside the high-vacuum multi-target magnetron sputtering coating system chamber, and then the vacuum was evacuated to 5*10. -3 After Pa, argon gas is introduced, and the gas flow controller is adjusted to maintain the pressure at 8 Pa. The radio frequency power supply is turned on, and p-xylene dimer films of different thicknesses are obtained by adjusting the sputtering power and sputtering time. The sputtering power is adjusted to 60 W, and sputtering is performed for 4 min to prepare p-xylene dimer films on the substrate. Finally, the gas is released and the sample is taken out.

[0031] (4) High-temperature annealing graphitizes p-xylene polymers to form graphene.

[0032] The p-xylene dimer film sample a prepared in (3) was placed in a rapid annealing furnace. The annealing temperature and time were adjusted to obtain the optimal temperature and annealing time for the graphitization of p-xylene dimer. A heating curve was set to raise the temperature to 900℃ within 10 seconds, hold for 30 seconds, and after cooling, the graphene film was obtained. The film thickness was measured to be approximately 4.65 nm by AFM characterization.

[0033] Example 2:

[0034] (1) Preparation of target material

[0035] p-xylene dimer blocks were selected as the carbon source, and the p-xylene dimer powder was compressed into cake-shaped p-xylene dimer blocks using a powder tableting machine. First, the p-xylene dimer block powder was loaded into a tableting machine mold with a diameter of 60 mm and compacted. Then, the mold was installed and a pressure of 10 MPa was applied. After releasing the air, the mold was removed to obtain p-xylene dimer blocks with a diameter of 60*5 mm.

[0036] (2) Cleaning the substrate

[0037] The SiO2 / Si substrate was ultrasonically cleaned for 10 min each with acetone solution, deionized water, and anhydrous ethanol. The cleaned substrate was then dried with nitrogen gas for later use.

[0038] (3) Coating

[0039] The substrate was fixed on the sample stage inside the high-vacuum multi-target magnetron sputtering coating system chamber, and then the vacuum was evacuated to 5*10. -3 After Pa, argon gas is introduced, and the gas flow controller is adjusted to maintain the pressure at 8 Pa. The radio frequency power supply is turned on, and p-xylene dimer films of different thicknesses are obtained by adjusting the sputtering power and sputtering time. The sputtering power is adjusted to 60 W, and sputtering is performed for 2 min to prepare p-xylene dimer films on the substrate. Finally, the gas is released and the sample is taken out.

[0040] (4) High-temperature annealing graphitizes p-xylene polymers to form graphene.

[0041] The p-xylene dimer film sample prepared in (3) was placed in a rapid annealing furnace. The annealing temperature and time were adjusted to obtain the optimal temperature and annealing time for the graphitization of p-xylene dimer. A heating curve was set to raise the temperature to 1000℃ within 10 seconds, hold for 30 seconds, and after cooling, the graphene film was obtained. The film thickness was measured to be approximately 1.5 nm by AFM characterization.

[0042] (5) Effects of sputtering time and annealing environment on the experiment

[0043]

[0044] Therefore, the best graphene layer is obtained when the sputtering power is 60W, the sputtering time is 2min, the annealing treatment crystallizes the p-xylene dimer film to form a graphene film, the annealing temperature is 1000℃, and the annealing time is 30s.

[0045] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for in-situ preparation of large-area graphene layers by magnetron sputtering, comprising the following steps: (1) Preparation of target material p-xylene dimer was selected as the carbon source, and the p-xylene dimer powder was pressed into cake-shaped p-xylene dimer blocks using a powder tableting machine; (2) Cleaning the substrate The substrate was ultrasonically cleaned by immersing it in acetone, deionized water, and anhydrous ethanol respectively to remove organic and inorganic particles and dust particles from the surface of the SiO2 / Si substrate, and then dried with nitrogen gas for later use. (3) Coating p-xylene polymer thin films were prepared on SiO2 / Si substrates by magnetron sputtering. (4) High-temperature annealing graphitizes p-xylene polymers to form graphene. The previously prepared sample was placed in a rapid annealing furnace, and a heating program with a heating curve was set to anneal the sample to obtain a graphene film.

2. The method according to claim 1, characterized in that, The specifications of the p-xylene dimer block target in step (1) are φ60*5mm.

3. The method according to claim 1, characterized in that, The magnetron sputtering power in step (3) is 60W, and the sputtering time is 2 or 4 minutes.

4. The method according to claim 1, characterized in that, The annealing temperature in step (4) is 900~1000℃ and the annealing time is 30s.

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