A method for removing graphene monolayer based on pulsed ion beam

Abstract

The present invention discloses a method for removing a single layer of graphene based on a pulsed ion beam, including controlling the sputtering energy and pulse width of the pulsed ion beam to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and bombarding the multilayer graphene with the pulsed ion beam at an angle, thereby selectively removing carbon atoms in the defective surface layer and retaining carbon atoms in the complete bottom layer at the same time. The present invention can be used for selective and controlled removal of atomic layers, and achieves precise exfoliation of large-scale single atomic layers. Compared with conventional technologies, the present invention is more controllable, has a wider processing window, higher performance and quality, and the pulsed ion beam can achieve batch acquisition of complete atomic layer surfaces over a large area, which can solve the problems of uncontrollable number of layers and low efficiency in existing graphene material removal methods, and provides a new graphene removal solution for graphene applications in semiconductors, light detection, and synthetic catalysis, expanding the potential for innovative applications of two-dimensional materials.

Description

Technical Field

[0001] The invention belongs to the technical field of two-dimensional material graphene preparation, and in particular relates to a method for removing a graphene single layer based on a pulsed ion beam. Background Art

[0002] Graphene has the highest electron transfer rate among known materials and excellent high-end properties such as thermal conductivity and modulus. It is widely used in electronics, catalysis, energy storage, and advanced composite materials. Common graphene preparation methods mainly include micromechanical exfoliation, chemical reduction oxidation, chemical vapor deposition, and crystal epitaxial growth. The number and size of graphene products produced by micromechanical exfoliation are uncontrollable and the yield is low. They are only used in laboratory research. The other methods are additive manufacturing methods, and it is difficult to control the number of graphene layers. However, in the fields of electronic devices, high quality requirements are placed on graphene, and its performance is closely related to the number of layers. Therefore, it is of great significance to accurately control the number of graphene layers by layer-by-layer exfoliation technology of graphene. Pulsed Iron Beam (PIB) micromachining technology starts with the beam extraction method of the ion beam, and realizes the stable output of nanosecond controllable variable frequency pulsed ion beam through time subdivision and frequency control, which improves the accuracy of ion beam control. However, this method still lacks selectivity for material removal, and it is difficult to achieve accurate removal of a single atomic layer. Summary of the invention

[0003] The technical problem to be solved by the present invention is as follows: In view of the above problems in the prior art, a method for removing a single layer of graphene based on a pulsed ion beam is provided. The present invention aims to solve the problem that the number of layers in the existing method for removing graphene materials is uncontrollable and the efficiency is low.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for removing a graphene single layer based on a pulsed ion beam comprises the following steps: controlling the sputtering energy and pulse width of the pulsed ion beam to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and bombarding the multilayer graphene with the pulsed ion beam at an angle, thereby selectively removing carbon atoms in the defective surface layer and retaining carbon atoms in the complete bottom layer at the same time.

[0006] Optionally, when the pulsed ion beam is obliquely incident to bombard the multilayer graphene, an angle between the pulsed ion beam and the normal direction of the multilayer graphene is an acute angle or an obtuse angle.

[0007] Optionally, the acute angle is 70 degrees.

[0008] Optionally, when the sputtering energy and pulse width of the controlled pulse ion beam are maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, the sputtering energy of the controlled pulse ion beam is achieved by controlling the screen grid voltage of the pulse ion beam.

[0009] Optionally, the sputtering energy and pulse width of the controlled pulsed ion beam are maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and before the pulsed ion beam is obliquely incident to bombard the multilayer graphene, a defective surface layer is formed on the surface of the multilayer graphene using the pulsed ion beam.

[0010] Optionally, forming a defective surface layer on the surface of the multilayer graphene using a pulsed ion beam comprises:

[0011] S1, adjusting the screen grid voltage of the pulsed ion beam to meet the minimum threshold voltage for sputtering carbon atoms, adjusting the pulse width of the pulsed ion beam to the initial pulse width and jumping to step S2 after the pulse width is stable;

[0012] S2, controlling the pulsed ion beam to bombard the surface of multilayer graphene to form a wavy stack perpendicular to the direction of the ion beam;

[0013] S3, gradually increasing the pulse width of the pulsed ion beam until a single-layer carbon atom tearing zone begins to appear on the defective surface layer of the multilayer graphene at the edge of the wavy stack, thereby forming a defective surface layer and exposing a complete bottom layer.

[0014] Optionally, the sputtering energy and pulse width of the pulsed ion beam are controlled to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene. When the pulsed ion beam is obliquely incident to bombard the multilayer graphene, the rotation angle of the multilayer graphene or the pulsed ion beam is adjusted so that the angle between the pulsed ion beam and the normal direction of the multilayer graphene is an acute angle or an obtuse angle; the pulse width is adjusted to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and the screen grid voltage of the pulsed ion beam is adjusted to a removal voltage that does not destroy the carbon atoms in the complete bottom layer so that the sputtering energy is maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and the removal voltage is less than the minimum threshold voltage that satisfies the sputtering of carbon atoms, thereby selectively removing the carbon atoms in the defective surface layer while retaining the carbon atoms in the complete bottom layer without destroying the carbon atoms in the complete bottom layer.

[0015] Optionally, the minimum threshold voltage for sputtering carbon atoms is 60V, and the removal voltage without destroying the complete bottom carbon atoms is 30V.

[0016] Optionally, the multilayer graphene is double-layer graphene.

[0017] Optionally, the sputtering energy and pulse width of the controlled pulse ion beam are maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and before the pulse ion beam is obliquely incident to bombard the multilayer graphene, double-layer graphene is prepared by mechanical exfoliation.

[0018] Compared with the prior art, the present invention mainly has the following advantages: the graphene monolayer removal method based on pulsed ion beam of the present invention includes controlling the sputtering energy and pulse width of the pulsed ion beam to maintain between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene with defective surface layer and complete bottom layer and bombarding the multilayer graphene with oblique incidence, thereby selectively removing the carbon atoms of the defective surface layer and retaining the carbon atoms of the complete bottom layer at the same time. The present invention can be used for selective and controlled removal of atomic layers, and realizes the precise exfoliation of large-scale single atomic layers. Compared with traditional technologies, the present invention is more controllable, has a wider processing window, higher performance and quality, and the pulsed ion beam can realize batch acquisition of complete atomic layer surfaces over a large area, which can effectively solve the problems of uncontrollable number of layers and low efficiency of existing graphene material removal methods, and provides a new graphene removal solution for graphene applications in semiconductors, light detection and synthetic catalysis, expanding the potential for innovative applications of two-dimensional materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the basic flow of the method of the embodiment of the present invention.

[0020] Figure 2 Schematic diagram of the single layer removal principle in an embodiment of the present invention.

[0021] Figure 3 This is the Raman spectrum of the left side of the sample after processing in the embodiment of the present invention.

[0022] Figure 4 This is the Raman spectrum on the right side of the sample after processing in the embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention adopts pulsed ion beam technology, and by utilizing the difference in sputtering thresholds between damaged atomic layers and intact atomic layers, the ion beam energy is precisely controlled to achieve selective and controlled removal of atomic layers, making it possible to accurately peel off a single atomic layer of graphene. Specifically, when the ion beam is sputtered, the defective and intact atomic layers exhibit different atomic behaviors. This is due to the change in surface bond energy. The atoms at the edge of the defect have a lower sputtering threshold than the atoms on the intact surface, making them easier to remove. By utilizing the difference in this sputtering threshold, the energy of the ion beam is adjusted between two specific thresholds to ensure that the surface defect atomic layer is completely removed while retaining the intact atomic layer of the subsurface. This controllable removal method can be used for accurate and rapid peeling of large-area intact atomic surfaces, providing a feasible solution for large-scale, high-quality preparation of graphene and various two-dimensional materials. The present invention is further described in detail below by taking the thinning of double-layer graphene into single-layer graphene as an example. There is no doubt that the method of this embodiment can be applied to multi-layer graphene for single-layer graphene removal, and finally can be obtained.

[0024] like Figure 1 As shown, this embodiment provides a method for removing a single layer of graphene based on a pulsed ion beam, comprising the following steps: controlling the sputtering energy and pulse width of the pulsed ion beam to remain between the sputtering thresholds of the defective surface layer and the intact bottom layer of the multilayer graphene, and bombarding the multilayer graphene with an oblique incidence of the pulsed ion beam, thereby selectively removing the carbon atoms in the defective surface layer and retaining the carbon atoms in the intact bottom layer at the same time. Figure 2 Schematic diagram of the single layer removal principle in an embodiment of the present invention, Figure 2 In the figure, a represents the complete bottom carbon atom, b represents the defective surface carbon atom, the black c represents the argon ion (Ar+ ion), the dashed line filled with gray c represents the Ar+ ion at the previous moment, and the dashed box represents the energy depletion of the Ar+ ion. Figure 2 It can be seen that at t 0 At this moment, the Ar+ ion c with energy E 0 The incident energy E 0 As shown by the arrow, the length of the arrow indicates its energy size, energy E 0 is less than the sputtering threshold of a complete atomic layer; at t 1 At this moment, due to the energy E of the Ar+ ion c 0 This interaction disturbs the carbon atoms a in the intact bottom layer and reduces the energy of the Ar+ ion c to E 1 At t 2At this moment, the Ar+ ion c exerts an upward force on the carbon atom b in the defect surface layer. Since the sputtering fracture threshold of the carbon atom b in the defect surface layer is lower, the CC bond connecting the carbon atom b and the carbon atom a in the intact bottom layer is broken, further reducing the energy of the Ar+ ion c to E 2 At t 3 At this moment, the energy of the Ar+ ion c is insufficient to continue to break more CC bonds, and this energy gradually dissipates after disturbing the remaining atoms. 4 The carbon atoms a in the complete bottom layer are restored to balance at all times, and finally the carbon atoms in the defective surface layer are selectively removed while retaining the carbon atoms in the complete bottom layer.

[0025] In this embodiment, when the pulsed ion beam is incident obliquely to bombard the multilayer graphene, the angle between the pulsed ion beam and the normal direction of the multilayer graphene is an acute angle or an obtuse angle. As an optional embodiment, in this embodiment, when the pulsed ion beam is incident obliquely to bombard the multilayer graphene, the angle between the pulsed ion beam and the normal direction of the multilayer graphene is an acute angle of 70 degrees.

[0026] There are different ways to control the sputtering energy of a pulsed ion beam. For example, as an optional implementation, in this embodiment, when the sputtering energy and pulse width of the pulsed ion beam are controlled to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, the sputtering energy of the pulsed ion beam is controlled by controlling the screen grid voltage of the pulsed ion beam.

[0027] It should be noted that the defective surface layer of the multilayer graphene can be either inherent to the multilayer graphene or specially processed. For example, as an optional implementation, the sputtering energy and pulse width of the pulsed ion beam are controlled to be maintained between the sputtering thresholds of the defective surface layer and the intact bottom layer of the multilayer graphene. Before the pulsed ion beam is obliquely incident to bombard the multilayer graphene, it also includes forming a defective surface layer on the surface of the multilayer graphene by using the pulsed ion beam.

[0028] In this embodiment, forming a defective surface layer on the surface of the multilayer graphene by using a pulsed ion beam includes:

[0029] S1, adjusting the screen grid voltage of the pulsed ion beam to meet the minimum threshold voltage for sputtering carbon atoms, adjusting the pulse width of the pulsed ion beam to the initial pulse width and jumping to step S2 after the pulse width is stable;

[0030] S2, controlling the pulsed ion beam to bombard the surface of multilayer graphene to form a wavy stack perpendicular to the direction of the ion beam;

[0031] S3, gradually increasing the pulse width of the pulsed ion beam until a single-layer carbon atom tearing zone begins to appear on the defective surface layer of the multilayer graphene at the edge of the wavy stack, thereby forming a defective surface layer and exposing a complete bottom layer.

[0032] In this embodiment, the sputtering energy and pulse width of the pulsed ion beam are controlled to be maintained between the sputtering thresholds of the defective surface layer and the intact bottom layer of the multilayer graphene. When the pulsed ion beam is obliquely incident to bombard the multilayer graphene, the rotation angle of the multilayer graphene or the pulsed ion beam is adjusted so that the angle between the pulsed ion beam and the normal direction of the multilayer graphene is an acute angle or an obtuse angle; the pulse width is adjusted to be maintained between the sputtering thresholds of the defective surface layer and the intact bottom layer of the multilayer graphene, and the screen grid voltage of the pulsed ion beam is adjusted to a removal voltage that does not destroy the carbon atoms in the intact bottom layer so that the sputtering energy is maintained between the sputtering thresholds of the defective surface layer and the intact bottom layer of the multilayer graphene, and the removal voltage is less than the minimum threshold voltage that satisfies the sputtering of carbon atoms, thereby selectively removing the carbon atoms in the defective surface layer while retaining the carbon atoms in the intact bottom layer without destroying the carbon atoms in the intact bottom layer.

[0033] In this embodiment, the minimum threshold voltage for sputtering carbon atoms is 60V, and the removal voltage without destroying the complete bottom carbon atoms is 30V.

[0034] In this embodiment, the sputtering energy and pulse width of the pulsed ion beam are controlled to be maintained between the sputtering thresholds of the defective surface layer and the intact bottom layer of the multilayer graphene, and the double-layer graphene is prepared by mechanical exfoliation before the pulsed ion beam is obliquely incident to bombard the multilayer graphene. In addition, other methods can also be used to prepare the double-layer graphene as needed.

[0035] In order to verify the graphene single layer removal method based on pulsed ion beam in this embodiment, pulsed ion beam sputtering is used in this embodiment to remove surface carbon atoms while retaining subsurface carbon atoms to verify the controllable removal of the single atomic layer. For the convenience of observation, the right half of the sample is blocked in the experiment, and only the left half is removed by sputtering through the graphene single layer removal method based on pulsed ion beam in this embodiment. The Raman spectra of the left and right sides of the sample after processing are as follows: Figure 3 and Figure 4 As shown in the figure, the horizontal axis is the Raman wavelength and the vertical axis is the relative density. G / I 2D ) is an important parameter used to characterize the number and quality of graphene layers, where I 2D represents the 2D peak intensity of graphene, I G Represents the G peak intensity of graphene. The 2D peak is a characteristic peak of graphene, which is generated by the vibration mode of two photonic lattices, while the G peak is generated by the vibration mode of one photonic lattice. Figure 3 and Figure 4 It can be seen that the relative density I of the mask area on the right G / I 2DThe ratio is 0.85, and the range of the double-layer graphene is between 0.7 and 1.3, indicating that this part is a relatively complete double-layer graphene. In contrast, the spectral G peak of the unblocked area on the left is significantly lower than that of the blocked area on the right, and its relative density I G / I 2D The D peak is 0.46, while the range for single-layer graphene is between 0.3 and 0.5. The small D peak indicates that the subsurface carbon atoms of the graphene sample are slightly modified. However, only a small part is sputtered away or misplaced, which is within the acceptable tolerance range and the atomic layer can still be considered intact.

[0036] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for removing a graphene monolayer based on a pulsed ion beam, characterized in that: The method comprises the following steps: controlling the sputtering energy and pulse width of the pulse ion beam to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and obliquely incidenting the pulse ion beam to bombard the multilayer graphene, thereby selectively removing carbon atoms in the defective surface layer and simultaneously retaining carbon atoms in the complete bottom layer; controlling the sputtering energy and pulse width of the pulse ion beam to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and obliquely incidenting the pulse ion beam to bombard the multilayer graphene, comprising adjusting the rotation angle of the multilayer graphene or the pulse ion beam, so that the pulse The angle between the ion beam and the normal direction of the multilayer graphene is an acute angle or an obtuse angle; the pulse width is adjusted to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and the screen grid voltage of the pulsed ion beam is adjusted to a removal voltage that does not destroy the carbon atoms in the complete bottom layer so that the sputtering energy is maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and the removal voltage is less than a minimum threshold voltage that satisfies the sputtering of carbon atoms, thereby selectively removing the carbon atoms in the defective surface layer and retaining the carbon atoms in the complete bottom layer without destroying the carbon atoms in the complete bottom layer; The sputtering energy and pulse width of the pulsed ion beam are controlled to be between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, and before the pulsed ion beam is obliquely incident to bombard the multilayer graphene, a defective surface layer is formed on the surface of the multilayer graphene by using the pulsed ion beam, including: S1, adjusting the screen grid voltage of the pulsed ion beam to meet the minimum threshold voltage for sputtering carbon atoms, adjusting the pulse width of the pulsed ion beam to the initial pulse width and jumping to step S2 after the pulse width is stable; S2, controlling the pulsed ion beam to bombard the surface of multilayer graphene to form a wavy stack perpendicular to the direction of the ion beam; S3, gradually increasing the pulse width of the pulsed ion beam until a single-layer carbon atom tearing zone begins to appear on the defective surface layer of the multilayer graphene at the edge of the wavy stack, thereby forming a defective surface layer and exposing a complete bottom layer.

2. The method for removing a graphene monolayer based on a pulsed ion beam according to claim 1, characterized in that: When the pulsed ion beam is obliquely incident to bombard the multilayer graphene, the angle between the pulsed ion beam and the normal direction of the multilayer graphene is an acute angle or an obtuse angle.

3. The method for removing a graphene monolayer based on a pulsed ion beam according to claim 2, characterized in that: The acute angle is 70 degrees.

4. The method for removing a graphene monolayer based on a pulsed ion beam according to claim 1, characterized in that: When the sputtering energy and pulse width of the controlled pulse ion beam are maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene, the sputtering energy of the controlled pulse ion beam is achieved by controlling the screen grid voltage of the pulse ion beam.

5. The method for removing a graphene monolayer based on a pulsed ion beam according to claim 1, characterized in that: The minimum threshold voltage for sputtering carbon atoms is 60V, and the removal voltage without destroying the complete bottom carbon atoms is 30V.

6. The method for removing a graphene monolayer based on a pulsed ion beam according to claim 1, characterized in that: The multilayer graphene is double-layer graphene.

7. The method for removing a graphene monolayer based on a pulsed ion beam according to claim 6, characterized in that: The sputtering energy and pulse width of the pulsed ion beam are controlled to be maintained between the sputtering thresholds of the defective surface layer and the complete bottom layer of the multilayer graphene. Before the pulsed ion beam is obliquely incident to bombard the multilayer graphene, double-layer graphene is prepared by mechanical exfoliation.

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