Method for assisting nucleation of graphene on surface of hexagonal boron nitride by plasma treatment

Abstract

The invention provides a method for assisting graphene nucleation on the surface of hexagonal boron nitride by plasma treatment. Comprising the following steps: step 1, preparing a substrate: preparing a hexagonal boron nitride sheet on the surface of a substrate, cleaning and annealing to obtain the substrate with the clean hexagonal boron nitride sheet on the surface; step 2, defect introduction: the substrate is placed in a chamber capable of generating plasma atmosphere, experimental gas is introduced, and boron nitride surface defect introduction treatment is carried out; and step 3, graphene growth and nucleation: placing the boron nitride into which the defects are introduced into a tubular furnace, and introducing a carbon source gas for graphene nucleation and growth. According to the method disclosed by the invention, defects are introduced on the surface of the hexagonal boron nitride by utilizing plasma pretreatment, and the nucleation density of the graphene is improved by utilizing the characteristic that defect positions can be used as graphene nucleation points, so that the growth efficiency of the graphene is improved.

Description

Technical Field

[0001] The invention relates to the field of graphene preparation methods, and in particular to a method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride. Background Art

[0002] As an important member of emerging materials, the preparation and application research of graphene is still an important development direction in the current materials field. In the field of microelectronics, how to achieve large-area preparation of graphene on the surface of insulating substrates to achieve transfer-free applications is a hot topic of research. Since hexagonal boron nitride is currently recognized internationally as the best substrate material for maintaining the intrinsic properties of graphene, the direct preparation of graphene on the surface of hexagonal boron nitride has become an important development direction.

[0003] The graphene nucleation density in existing preparation methods is generally low, which limits the efficiency of graphene preparation. Moreover, during the long-term graphene growth process, amorphous carbon aggregates are easily formed on the graphene surface, which seriously affects the performance of graphene.

[0004] In order to overcome the above problems, the present invention proposes a new method for preparing graphene on the surface of hexagonal boron nitride by plasma pretreatment. The present invention pretreats the substrate by plasma to introduce defects on its surface, and then grows graphene by chemical vapor deposition. The method involved in the present invention has a significant promoting effect on the nucleation of graphene growth, significantly improves the growth efficiency of graphene, and by extending the graphene growth time, it can achieve the preparation of a graphene film with full coverage of the hexagonal boron nitride surface in a relatively short time. Summary of the invention

[0005] The purpose of the invention is to provide a method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention relates to a method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride, comprising the following steps:

[0008] Step 1, substrate preparation: prepare hexagonal boron nitride flakes on the substrate surface by mechanical exfoliation or chemical vapor deposition, clean and anneal the sample to obtain a substrate with hexagonal boron nitride flakes attached to the surface;

[0009] Step 2, defect introduction: placing the substrate with the hexagonal boron nitride flakes attached to the surface into a chamber that can generate a plasma atmosphere, introducing the experimental gas at room temperature, and using plasma to introduce defects into the hexagonal boron nitride surface;

[0010] Step 3, graphene growth: the sample after defect introduction is placed in a tube furnace, and carbon source gas is introduced at 1300° C. to grow graphene.

[0011] Preferably, in step 1, the cleaning step is acetone cleaning for 5 minutes; the temperature of the annealing treatment is 650° C., the annealing atmosphere is pure oxygen, the pressure is 20-100 Pa, and the annealing time is 1-2 hours.

[0012] Preferably, in step 2, the experimental gas is oxygen or argon.

[0013] Preferably, the flow rate of the experimental gas is 10-100 sccm, and the pressure is 10-100 Pa.

[0014] Preferably, in step 2, the device for generating plasma in the chamber is a plasma enhanced chemical vapor deposition system or a plasma cleaning machine.

[0015] Preferably, in step 2, the radio frequency power of the equipment generating plasma in the chamber has a power of 10 to 50 W.

[0016] Preferably, in step 2, the defect introduction treatment time is 1 to 10 minutes.

[0017] Preferably, in step 3, the carbon source gas is methane, acetylene and a mixture thereof.

[0018] Preferably, the flow rate of the carbon source gas is 50-200 sccm.

[0019] Preferably, the growth time is 1 to 3 hours, and the growth pressure is 10 to 100 Pa or normal pressure.

[0020] The principle of the method involved in the present invention is that since the growth of graphene on the surface of hexagonal boron nitride usually nucleates at defects or steps, the present invention uses plasma to pretreat the hexagonal boron nitride, introduces defects on its surface, and uses chemical vapor deposition to grow graphene on the defective surface, so that the graphene growth has more nucleation points, thereby forming a continuous graphene film on the surface of hexagonal boron nitride in a shorter time.

[0021] The present invention has the following advantages:

[0022] (1) The method of the present invention pre-treats the substrate by plasma to introduce defects on its surface, and then grows graphene by chemical vapor deposition. The present invention has a significant promoting effect on graphene nucleation, significantly improves the growth efficiency of graphene, and by extending the graphene growth time, can achieve the preparation of a graphene film with full coverage of the hexagonal boron nitride surface in a relatively short time.

[0023] (2) The method of the present invention improves the growth efficiency of graphene on the surface of an insulating hexagonal boron nitride substrate, without the need to plate a metal film on the substrate surface, thereby avoiding damage and contamination to the graphene during the film removal process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a comparison diagram of AFM images of graphene grown by the method of the present invention and the prior art;

[0025] Figure 2 This is a diagram demonstrating the process of introducing defective graphene nucleation according to the present invention. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments are only further descriptions of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0027] Example 1

[0028] This embodiment relates to a method for using plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride, comprising the following steps:

[0029] Step 1, substrate preparation: prepare hexagonal boron nitride flakes on the substrate surface by mechanical exfoliation or chemical vapor deposition, clean the sample with acetone solution and anneal with oxygen at 650°C for 1 hour to obtain a substrate with clean hexagonal boron nitride flakes attached to the surface;

[0030] Step 2, defect introduction: Place the substrate with the hexagonal boron nitride thin film on the surface into a chamber equipped with a plasma enhanced chemical vapor deposition system (RF power of 10 W), introduce argon gas (flow rate of 10 sccm, pressure of 10 Pa) at room temperature, and use plasma to introduce defects on the hexagonal boron nitride surface for 10 minutes;

[0031] Step 3, graphene growth: Place the sample after defect introduction in a tube furnace, introduce a mixed gas (flow rate of 100 sccm) of carbon source gas (methane and acetylene in a volume ratio of 4:96) at 1300°C, and grow graphene for 1 hour under normal pressure.

[0032] Example 2

[0033] This embodiment relates to a method for using plasma treatment to assist graphene nucleation growth on the surface of hexagonal boron nitride, comprising the following steps:

[0034] Step 1, substrate preparation: prepare hexagonal boron nitride flakes on the substrate surface by mechanical stripping or chemical vapor deposition, clean the sample with acetone solution and anneal with oxygen at 650°C for 2h to obtain a substrate with clean hexagonal boron nitride flakes on the surface;

[0035] Step 2, defect introduction: Place the substrate with the hexagonal boron nitride flakes on the surface into the chamber of a plasma cleaning machine (RF power of 50 W), introduce oxygen (flow rate of 50 sccm, pressure of 50 Pa) at room temperature, and use plasma to introduce defects on the hexagonal boron nitride surface for 2 minutes;

[0036] Step 3, graphene growth: Place the sample after defect introduction in a tube furnace, introduce methane gas (flow rate of 100 sccm) at 1300°C, and grow graphene for 3 hours under normal pressure.

[0037] Comparative Example

[0038] The method of this comparative example is different from the above-mentioned embodiments 1-2 of the present invention in that it does not involve a defect introduction step.

[0039] The graphene film fully covered on the surface of hexagonal boron nitride prepared by the method of the present invention is compared with the comparative example. Figure 1 As shown (the left is an AFM image of graphene directly grown by the comparative method, and the right is an AFM image of graphene grown after defects are introduced by the method of the present invention), it can be seen from the comparison that the method of the present invention greatly improves the efficiency of graphene growth on the surface of the insulating hexagonal boron nitride substrate. Figure 2 As shown, the graphene nucleation density is greatly improved after the defects are introduced in the present invention.

[0040] The present invention utilizes a plasma treatment-assisted method for graphene nucleation on the surface of hexagonal boron nitride, utilizes plasma pretreatment to controllably introduce defects on the surface of hexagonal boron nitride, and performs graphene nucleation growth at the defect positions by chemical vapor deposition, thereby increasing the graphene nucleation density and realizing the preparation of a graphene film on the surface of hexagonal boron nitride.

[0041] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which will not affect the essence of the present invention.

Claims

1. A method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride, characterized in that: The following steps are involved: Step 1, substrate preparation: prepare hexagonal boron nitride flakes on the substrate surface by mechanical exfoliation or chemical vapor deposition, clean and anneal the sample to obtain a substrate with clean hexagonal boron nitride flakes attached to the surface; Step 2, defect introduction: placing the substrate with the hexagonal boron nitride flakes attached to the surface into a chamber that can generate a plasma atmosphere, introducing the experimental gas at room temperature, and using plasma to introduce defects into the hexagonal boron nitride surface; Step 3, graphene growth: the sample after defect introduction is placed in a tube furnace, and carbon source gas is introduced at 1300° C. to grow graphene.

2. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 1, characterized in that: In step 1, the cleaning is specifically: cleaning with acetone solution for 5 minutes; the temperature of the annealing treatment is 650° C., the annealing atmosphere is pure oxygen, the pressure is 20-100 Pa, and the annealing time is 1-2 hours.

3. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 1, characterized in that: In step 2, the experimental gas is oxygen or argon.

4. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 1 or 3, characterized in that: The flow rate of the experimental gas is 10-100 sccm, and the pressure is 10-100 Pa.

5. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 1, characterized in that: In step 2, the device capable of generating plasma in the chamber is a plasma enhanced chemical vapor deposition system or a plasma cleaning machine.

6. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 5, characterized in that: The radio frequency power of the equipment capable of generating plasma in the chamber is 10-50W.

7. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 1, characterized in that: In step 2, the defect introduction treatment time is 1 to 10 minutes.

8. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 1, characterized in that: In step 3, the carbon source gas is methane, acetylene and a mixture thereof.

9. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 8, characterized in that: The flow rate of the carbon source gas is 50-200 sccm.

10. The method for utilizing plasma treatment to assist graphene nucleation on the surface of hexagonal boron nitride as claimed in claim 1, characterized in that: In step 3, the growth time is 1 to 3 hours, and the growth pressure is 10 to 100 Pa or normal pressure.

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