A method for preparing a single crystal diamond / graphene heterojunction
Patent Information
- Application Number
- CN202611260623.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-19
- Publication Date
- 2026-09-25
AI Technical Summary
[0005]本发明的目的在于提供一种单晶金刚石/石墨烯异质结的制备方法，旨在解决现有技术中对于石墨烯的形成区域的可控性低的问题
[0016]本发明所提供的一种单晶金刚石/石墨烯异质结的制备方法，相比于现有技术，其通过第一轮划擦在单晶金刚石表层或亚表层形成受限亚表层结构调控层，该划痕区因机械诱导产生了远高于基体的缺陷能和局部结构活性，后续该划痕区再经过划擦催化处理，两次划擦的深度均控制在0.5~5 nm范围内，仅扰动表层结构而不破坏衬底整体结构；在催化退火过程中，仅该划痕区能够优先发生石墨化相变，未进行双重处理的区域即使在相同催化氛围和温度条件下也几乎不发生相变。经拉曼光谱表征，划痕区可检测到明显的石墨烯G峰和2D峰，非划痕区无对应特征信号，选择性生长效果明确。可见，本发明通过所提供的步骤的组合，省去了传统石墨烯制备所需的光刻、刻蚀等复杂工序后也能实现石墨烯在金刚石表面的选择性原位生长，但工艺成本大幅降低；同时，通过划擦的方式能够更精准地控制石墨烯转化区域，也更容易实现石墨烯图案化，以较低的成本解决了现有技术中对于石墨烯的形成区域的可控性低的问题。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of two-dimensional graphene material preparation technology, and in particular to a method for preparing a single-crystal diamond / graphene heterojunction. Background Technology
[0002] Integrated circuit technology is a crucial support for the development of national strategic emerging industries such as information technology, new energy, and intelligent manufacturing. As device dimensions continue to shrink, the traditional Moore's Law is gradually approaching its physical limits, and the development of new devices in the post-Moore's Law era places higher demands on material systems and structural design.
[0003] The International Devices and Systems Roadmap (IRDS) points out that the synergistic construction of hybrid-dimensional heterostructure devices with complex functions through the synergistic use of semiconductor materials of different dimensions is an important way to achieve the continuous evolution of integrated circuit technology in the post-Moore era. Single-crystal diamond has a high breakdown electric field, high thermal conductivity, and excellent chemical stability, while graphene has ultra-high carrier mobility and good electrical properties. The single-crystal diamond / graphene heterojunction formed by combining the two has good application prospects in high-power electronic devices, high-frequency communication devices, and novel information devices.
[0004] Currently, there are various technical routes for the preparation of single-crystal diamond / graphene heterostructures, including graphene transfer method, high-temperature direct growth method and metal catalytic annealing method. The above methods have achieved heterogeneous integration of diamond and graphene to a certain extent, but the above methods generally have problems such as complex process flow, high processing temperature and high process cost; at the same time, it is difficult to precisely control the number and uniformity of graphene layers; furthermore, the controllability of the graphene formation region is also low. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing single-crystal diamond / graphene heterojunctions, aiming to solve the problem of low controllability of graphene formation region in the prior art.
[0006] To achieve the above objectives, this invention provides a method for preparing a single-crystal diamond / graphene heterostructure, comprising the following steps: S1, fixing a single-crystal diamond substrate on a heating stage, the heating stage being placed within a working space; S2, purging the working space with an inert gas to form a protective atmosphere, and using a diamond indenter to perform a first round of scratching on the single-crystal diamond substrate under this protective atmosphere, with a total scratching depth of 0.5~5 nm, to form a confined subsurface structure control layer on the surface or subsurface of the single-crystal diamond substrate; S3, heating the single-crystal diamond substrate to 600~700 °C using the heating stage, and holding at this temperature for 0.5~10 min; while maintaining the inert gas protective atmosphere, introducing hydrogen gas into the working space to achieve a hydrogen volume concentration of 1.0%~2.0%, forming a catalytic atmosphere; and maintaining the single-crystal diamond substrate at 600~700 °C under this catalytic atmosphere. At a temperature of ℃, a diamond indenter with a catalytic layer is used to perform a second round of scratching on the restricted subsurface structure control layer formed in step S2, with a total scratching depth of 0.5~5 nm, to catalyze the restricted subsurface structure control layer; S4, the working space is purged with inert gas to remove residual hydrogen and re-establish a protective atmosphere, and then the single-crystal diamond substrate is subjected to cooling annealing treatment at a cooling rate of 20~40 ℃ / min, so that the scratched area that has undergone the first round of scratching and the superimposed second round of scratching preferentially undergoes local phase transition and is converted into graphene in situ; S5, the catalytic material remaining on the single-crystal diamond substrate is removed to obtain a single-crystal diamond / graphene heterojunction.
[0007] Furthermore, in step S2, the parameters for the first round of scrubbing are: performed at room temperature, scrubbing pressure of 100~500mN, scanning speed of 1~10 μm / s, and number of scans of 5~30.
[0008] Furthermore, in step S3, the catalyst layer is a Ni / Cu composite metal catalyst layer, the molar ratio of Ni to Cu is 7:3 to 6:4, and the thickness of the catalyst layer is 100 to 200 nm.
[0009] Furthermore, the Ni / Cu composite metal catalyst layer was prepared by magnetron sputtering, with a sputtering time of 20-40 min, a sputtering power of 100-150 W, and a working pressure of 0.4-1.1 Pa.
[0010] Furthermore, in step S3, the parameters for the second round of scrubbing are: scrubbing pressure of 500~800 mN, scanning speed of 1~10 μm / s, and number of scans of 30~50.
[0011] Furthermore, in step S2 and / or step S3, the diamond indenter is a conical indenter or a Berkovich indenter, and the equivalent radius of curvature of the tip of the diamond indenter is 1~5 μm.
[0012] Furthermore, in steps S2 and / or S4, the inert gas is argon, nitrogen, or helium.
[0013] Furthermore, in step S5, the method for removing the residual catalyst material on the single-crystal diamond substrate is to clean the residual catalyst material with dilute nitric acid, dilute hydrochloric acid, or dilute sulfuric acid.
[0014] Furthermore, the single-crystal diamond substrate is a (100)-plane single-crystal diamond substrate or a (111)-plane single-crystal diamond substrate.
[0015] Furthermore, the single-crystal diamond / graphene heterojunction comprises a single layer of graphene or 2 to 10 layers of graphene.
[0016] This invention provides a method for preparing single-crystal diamond / graphene heterojunctions. Compared to existing technologies, this method involves forming a restricted subsurface structure control layer on the surface or subsurface of single-crystal diamond through a first-round scratching process. This scratched region exhibits defect energy and local structural activity significantly higher than the substrate due to mechanical induction. Subsequently, this scratched region undergoes a scratch-catalytic treatment, with the depth of both scratches controlled within the range of 0.5–5 nm, disturbing only the surface structure without damaging the overall substrate structure. During catalytic annealing, only the scratched region preferentially undergoes a graphitization phase transition; regions without this dual treatment show almost no phase transition even under the same catalytic atmosphere and temperature conditions. Raman spectroscopy characterization reveals distinct graphene G and 2D peaks in the scratched region, while no corresponding characteristic signals are observed in the non-scratched region, demonstrating a clear selective growth effect. As can be seen, by combining the steps provided in this invention, the complex processes such as photolithography and etching required for traditional graphene preparation can be eliminated, and graphene can still be selectively grown in situ on the diamond surface, while significantly reducing the process cost. At the same time, the graphene conversion area can be controlled more precisely by scratching, and graphene patterning can be achieved more easily. This solves the problem of low controllability of the graphene formation area in the prior art at a lower cost. Attached Figure Description
[0017] Figure 1 This is a comparison curve of the radial distribution function of the single-crystal diamond substrate before and after annealing in Example 1;
[0018] Figure 2 This is a surface morphology diagram of the single-crystal diamond substrate after annealing in Example 1;
[0019] Figure 3 This is an optical microscope image of the surface of the single-crystal diamond / graphene heterojunction in Example 1;
[0020] Figure 4 This is a comparison of the Raman spectra of the scratched and unscratched areas in Example 1. Detailed Implementation
[0021] The embodiments of the present invention will be described in detail below.
[0022] This invention provides a method for preparing a single-crystal diamond / graphene heterojunction, which includes the following steps.
[0023] S1. Fix the single-crystal diamond substrate on the heating stage, which is placed in the working space. The heating stage is used to heat the single-crystal diamond substrate. The working space is a space with an air inlet and an air outlet. The air inlet and outlet are used for gas to enter and exit when inert gas is purged or hydrogen is added. When necessary, the air inlet and outlet can be closed to maintain a specific atmosphere in the working space. Of course, gas can also be continuously input into the air inlet and discharged from the air outlet to maintain a specific atmosphere in the working space.
[0024] S2. The working space is purged with an inert gas to form a protective atmosphere. The inert gas is argon, nitrogen or helium. Under the protective atmosphere, a diamond indenter with a tip equivalent radius of curvature of 1~5 μm is used to perform the first round of scratching on the single crystal diamond substrate. The total scratching depth of the first round of scratching is 0.5~5 nm. The parameters are: performed at room temperature, scratching pressure of 100~500mN, scanning speed of 1~10 μm / s, and 5~30 scans, so as to form a restricted subsurface structure control layer on the surface or subsurface of the single crystal diamond substrate.
[0025] S3. The single-crystal diamond substrate is heated to 600~700 ℃ using a heating stage and held at that temperature for 0.5~10 min. Hydrogen gas is introduced into the working space while maintaining an inert gas protective atmosphere, so that the hydrogen volume concentration in the working space reaches 1.0%~2.0%, forming a catalytic atmosphere. Under the catalytic atmosphere and with the single-crystal diamond substrate maintained at 600~700 ℃, a diamond indenter with a catalytic layer and a tip equivalent radius of curvature of 1~5 μm is used to perform a second round of scrubbing on the restricted subsurface structure control layer formed in step S2. The total scrubbing depth of the second round is 0.5~5 nm, and the parameters are: scrubbing pressure of 500~800 mN, scanning speed of 1~10 μm / s, and 30~50 scans, to catalyze the restricted subsurface structure control layer. The catalyst layer is a Ni / Cu composite metal catalyst layer with a molar ratio of Ni to Cu of 7:3 to 6:4 and a thickness of 100 to 200 nm. The Ni / Cu composite metal catalyst layer is prepared by magnetron sputtering with a sputtering time of 20 to 40 min, a sputtering power of 100 to 150 W, and a working pressure of 0.4 to 1.1 Pa.
[0026] S4. The working space is purged with an inert gas to remove residual hydrogen and re-establish a protective atmosphere. The inert gas is argon, nitrogen, or helium. Then, the single-crystal diamond substrate is subjected to cooling annealing at a cooling rate of 20~40 ℃ / min, so that the scratched area that has undergone the first round of scratching and the superimposed second round of scratching preferentially undergoes local phase transformation and is converted into graphene in situ.
[0027] S5. Remove the residual catalyst material on the single-crystal diamond substrate by cleaning it with dilute nitric acid, dilute hydrochloric acid or dilute sulfuric acid, followed by further cleaning with deionized water and anhydrous ethanol, and finally drying to obtain a single-crystal diamond / graphene heterojunction. The single-crystal diamond / graphene heterojunction includes a single layer of graphene or 2 to 10 layers of graphene.
[0028] Based on the above-described steps, this invention forms a restricted subsurface structure control layer on the surface or subsurface of single-crystal diamond through a first round of scratching. This scratched region exhibits defect energy and local structural activity far exceeding that of the substrate due to mechanical induction. Subsequently, this scratched region undergoes a scratch-catalytic treatment, with the depth of both scratches controlled within the range of 0.5–5 nm, disturbing only the surface structure without damaging the overall substrate structure. During catalytic annealing, only this scratched region preferentially undergoes a graphitization phase transition; regions without the dual treatment show almost no phase transition even under the same catalytic atmosphere and temperature conditions. Raman spectroscopy characterization reveals distinct graphene G and 2D peaks in the scratched region, while no corresponding characteristic signals are found in the non-scratched region, demonstrating a clear selective growth effect. As can be seen, by combining the steps provided in this invention, the complex processes such as photolithography and etching required for traditional graphene preparation can be eliminated, and graphene can still be selectively grown in situ on the diamond surface, while significantly reducing the process cost. At the same time, the graphene conversion area can be controlled more precisely by scratching, and graphene patterning can be achieved more easily. This solves the problem of low controllability of the graphene formation area in the prior art at a lower cost.
[0029] This invention controls the in-situ growth temperature of graphene at 600~700℃, a temperature reduction of over 20% compared to the >900℃ required by traditional high-temperature metal catalysis methods. The lower growth temperature avoids problems such as spontaneous graphitization and lattice distortion that occur in single-crystal diamond at high temperatures, preserving the excellent electrical and thermal properties of the single-crystal diamond substrate itself. It also reduces the requirements for the high-temperature resistance of equipment, thus reducing energy consumption. Simultaneously, by controlling the hydrogen volume concentration within a narrow range of 1.0%~2.0%, the catalytic activity of the Ni / Cu composite metal catalyst layer is ensured while avoiding excessive etching of the single-crystal diamond by high-concentration hydrogen, further protecting the integrity of the single-crystal diamond substrate.
[0030] This invention adjusts the scratching pressure and scanning parameters of the first and second scratching cycles to regulate the intensity of the catalytic effect, and can stably control the final graphene to be a single layer or 2 to 10 layers. The controllability of the number of layers is significantly better than that of traditional thermal annealing and high-temperature metal catalytic annealing.
[0031] This invention employs a Ni / Cu composite metal catalyst layer, which exhibits superior overall performance compared to single Ni or Cu catalyst layers. Ni possesses strong carbon dissolution and catalytic graphitization capabilities, but when used alone, it can easily lead to excessive graphene growth and uncontrolled layer number. Cu has low carbon solubility, which can inhibit excessive graphene nucleation. The above combination ensures catalytic activity while limiting graphene growth to a controllable layer number range, resulting in good controllability.
[0032] The method of this invention can achieve selective growth of high-quality graphene on both (100)-plane and (111)-plane single-crystal diamond substrates, without relying on a specific crystal orientation. It can be implemented directly using common commercial substrates without customized processing. At the same time, argon, nitrogen or helium can be used as the inert gas, and a conical indenter or a Berkovich indenter can be used as the diamond indenter. The key process parameters have a wide range of applicability, strong adaptability to equipment and raw materials, and are easy to promote industrialization.
[0033] Example 1
[0034] The specific method for preparing the single-crystal diamond / graphene heterojunction in this embodiment is as follows:
[0035] S1. Select a (100) plane single crystal diamond substrate, fix the single crystal diamond substrate on the heating stage, and place the heating stage in the working space.
[0036] S2. Argon gas is used to purge the working space to form a protective atmosphere. Under the protective atmosphere, a conical diamond indenter with a tip equivalent radius of curvature of 2 μm is used to perform the first round of scratching on the single crystal diamond substrate. The total scratching depth of the first round is 0.5 nm. The parameters are: scratching pressure of 100 mN, scanning speed of 5 μm / s, and 15 scans, in order to form a restricted subsurface structure control layer on the surface or subsurface of the single crystal diamond substrate.
[0037] S3. The single-crystal diamond substrate is heated to 650 °C using a heating stage and held at that temperature for 0.5 min. While maintaining an inert gas protective atmosphere, hydrogen gas is introduced into the working space to achieve a hydrogen volume concentration of 1.0%, forming a catalytic atmosphere. Under this catalytic atmosphere and with the single-crystal diamond substrate maintained at 650 °C, a second round of scrubbing is performed on the confined subsurface structure control layer formed in step S2 using a diamond indenter with a catalytic layer and a tip equivalent radius of curvature of 2 μm. The total scrubbing depth of the second round is 2 nm, with the following parameters: scrubbing pressure of 600 mN, scanning speed of 5 μm / s, and 40 scans, to catalyze the confined subsurface structure control layer. The catalytic layer is a Ni / Cu composite metal catalytic layer with a Ni to Cu molar ratio of 7:3 and a thickness of 150 nm.
[0038] S4. Argon gas is used to purge the working space to remove residual hydrogen and re-form a protective atmosphere; then, the single crystal diamond substrate is subjected to cooling annealing at a cooling rate of 30 ℃ / min, so that the scratched area that has undergone the first round of scratching and the superimposed second round of scratching preferentially undergoes local phase transformation and is transformed into graphene in situ.
[0039] S5. Remove the residual catalyst material on the single-crystal diamond substrate. Clean the residual catalyst material with dilute nitric acid, then clean it further with deionized water and anhydrous ethanol in sequence, and finally dry it to obtain a single-crystal diamond / graphene heterojunction. The single-crystal diamond / graphene heterojunction includes 3 to 4 layers of graphene.
[0040] The experimental measurement results of Example 1 are as follows: Figures 1 to 4 As shown. By Figure 1 As can be seen, the RDF curve of the single-crystal diamond substrate before annealing exhibits a sharp first nearest-neighbor peak at approximately 0.154 nm, corresponding to the CC bond characteristics of sp³ hybridized carbon atoms in the diamond crystal. After annealing, a new first nearest-neighbor peak appears in the RDF curve at approximately 0.142 nm, which coincides with the characteristic bond length of the CC bond in the sp² hybridized graphene structure. Simultaneously, the second nearest-neighbor peak near 0.25 nm in the annealed curve shows significant broadening and a shift towards lower values, indicating that the local atomic arrangement order evolves from the cubic lattice structure of diamond to the hexagonal layered structure of graphite. These RDF changes indicate that carbon atoms change from sp³ hybridized carbon atoms to a more uniform, more uniform structure. 3 Hybridization towards sp 2 The hybridization transition provides direct atomic-scale evidence of the diamond-to-graphene transformation occurring in this region. Figure 2 As can be seen, in the scratched areas after two rounds of scratching, the substrate surface exhibits a continuous sheet-like wrinkled structure, a morphology consistent with the typical surface morphology of graphene; while the unscratched areas remain smooth and flat, with no graphitization products observed. Figure 3 As can be seen, there are multiple dark-colored banded areas distributed along the scratching path on the substrate surface. The edges of the lines are regular and the continuity is good. There is no breakage or large-area diffusion. In contrast, no similar dark-colored banded structures were observed in other areas of the substrate. Figure 3 The results further confirm that this invention can achieve patterned preparation of graphene on the surface of a single-crystal diamond substrate, and the distribution position, shape, and orientation of the graphene can be precisely controlled. Figure 4 As can be seen, the spectrum of the scratched area is at approximately 1580 cm⁻¹. -1 A distinct G peak appears at approximately 2700 cm. -1 A 2D peak appears at approximately 1350 cm⁻¹. -1 A faint D peak is visible nearby. This spectral characteristic is basically consistent with the standard Raman fingerprint of graphene, where the G peak originates from sp. 2 The in-plane stretching vibrations of carbon atoms, with the 2D peak originating from second-order two-phonon scattering, reflect the contribution of disordered scattering at graphene edges or defects. In contrast, the non-scratched region spectrum does not exhibit characteristic peaks at these locations, only showing a peak at approximately 1332 cm⁻¹. -1 The presence of characteristic peaks of diamond indicates that the region still retains a complete diamond sp. 3 The hybrid structure did not undergo graphitization. This verifies the feasibility of the method of the present invention and the controllability of the graphene formation region.
[0041] Example 2
[0042] The specific method for preparing the single-crystal diamond / graphene heterojunction in this embodiment is as follows:
[0043] S1. Select a (111) plane single crystal diamond substrate, fix the single crystal diamond substrate on the heating stage, and place the heating stage in the working space.
[0044] S2. Nitrogen gas is used to purge the working space to create a protective atmosphere. Under the protective atmosphere, a Berkovich diamond indenter with a tip equivalent radius of curvature of 5 μm is used to perform the first round of scratching on the single crystal diamond substrate. The total scratching depth of the first round is 5 nm, and the parameters are: scratching pressure of 400 mN, scanning speed of 2 μm / s, and 25 scans, in order to form a restricted subsurface structure control layer on the surface or subsurface of the single crystal diamond substrate.
[0045] S3. The single-crystal diamond substrate is heated to 700 °C using a heating stage and held at this temperature for 1 min. While maintaining an inert gas protective atmosphere, hydrogen gas is introduced into the working space to achieve a hydrogen volume concentration of 2.0%, forming a catalytic atmosphere. Under this catalytic atmosphere and with the single-crystal diamond substrate maintained at 700 °C, a second round of scrubbing is performed on the confined subsurface structure control layer formed in step S2 using a diamond indenter with a catalytic layer and a tip equivalent radius of curvature of 5 μm. The total scrubbing depth of the second round is 5 nm, with the following parameters: scrubbing pressure of 800 mN, scanning speed of 2 μm / s, and 50 scans, to catalyze the confined subsurface structure control layer. The catalytic layer is a Ni / Cu composite metal catalytic layer with a Ni to Cu molar ratio of 7:3 and a thickness of 200 nm.
[0046] S4. Nitrogen gas is used to purge the working space to remove residual hydrogen and re-form a protective atmosphere. Then, the single-crystal diamond substrate is subjected to cooling annealing at a cooling rate of 40 °C / min, so that the scratched area that has undergone the first round of scratching and the superimposed second round of scratching preferentially undergoes local phase transition and is converted into graphene in situ.
[0047] S5. Remove the residual catalyst material on the single-crystal diamond substrate. Clean the residual catalyst material with dilute hydrochloric acid, then clean it further with deionized water and anhydrous ethanol in sequence, and finally dry it to obtain a single-crystal diamond / graphene heterojunction. The single-crystal diamond / graphene heterojunction includes 8 to 10 layers of graphene.
[0048] Example 3
[0049] The specific method for preparing the single-crystal diamond / graphene heterojunction in this embodiment is as follows:
[0050] S1. Select a (111) plane single crystal diamond substrate, fix the single crystal diamond substrate on the heating stage, and place the heating stage in the working space.
[0051] S2. The working space is purged with helium to form a protective atmosphere. Under the protective atmosphere, a conical diamond indenter with a tip equivalent radius of curvature of 1 μm is used to perform the first round of scratching on the single crystal diamond substrate. The total scratching depth of the first round is 1 nm. The parameters are: scratching pressure of 200 mN, scanning speed of 5 μm / s, and 5 scans, so as to form a restricted subsurface structure control layer on the surface or subsurface of the single crystal diamond substrate.
[0052] S3. The single-crystal diamond substrate is heated to 600 °C using a heating stage and held at that temperature for 10 min. While maintaining an inert gas protective atmosphere, hydrogen gas is introduced into the working space to achieve a hydrogen volume concentration of 1.0%, forming a catalytic atmosphere. Under this catalytic atmosphere and with the single-crystal diamond substrate maintained at 600 °C, a second round of scrubbing is performed on the confined subsurface structure control layer formed in step S2 using a diamond indenter with a catalytic layer and a tip equivalent radius of curvature of 1 μm. The total scrubbing depth of the second round is 1 nm, with the following parameters: scrubbing pressure of 500 mN, scanning speed of 5 μm / s, and 30 scans, to catalyze the confined subsurface structure control layer. The catalytic layer is a Ni / Cu composite metal catalytic layer with a Ni to Cu molar ratio of 6:4 and a thickness of 100 nm.
[0053] S4. The working space is purged with helium to remove residual hydrogen and re-establish a protective atmosphere; then, the single-crystal diamond substrate is subjected to cooling annealing at a cooling rate of 40 ℃ / min, so that the scratched area that has undergone the first round of scratching and the superimposed second round of scratching preferentially undergoes local phase transition and is converted into graphene in situ.
[0054] S5. Remove the residual catalytic material on the single-crystal diamond substrate. Clean the residual catalytic material with dilute sulfuric acid, then further clean it with deionized water and anhydrous ethanol in sequence, and finally dry it to obtain a single-crystal diamond / graphene heterojunction. The single-crystal diamond / graphene heterojunction includes a single layer of graphene.
[0055] Where there is no conflict, the above embodiments and features can be combined with each other.
[0056] Finally, it should be noted that the above embodiments are only used to illustrate the preferred technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the present invention.
Claims
1. A method for preparing a single-crystal diamond / graphene heterojunction, characterized in that, Includes the following steps: S1. Fix the single-crystal diamond substrate onto the heating stage, and place the heating stage within the work space; S2. The working space is purged with inert gas to form a protective atmosphere. Under the protective atmosphere, a diamond indenter is used to perform the first round of scratching on the single crystal diamond substrate. The total scratching depth is 0.5~5 nm, so as to form a restricted subsurface structure control layer on the surface or subsurface of the single crystal diamond substrate. S3. The single-crystal diamond substrate is heated to 600~700 ℃ using a heating stage and held at that temperature for 0.5~10 min. While maintaining an inert gas protective atmosphere, hydrogen gas is introduced into the working space to achieve a hydrogen volume concentration of 1.0%~2.0% to form a catalytic atmosphere. Under the catalytic atmosphere and with the single-crystal diamond substrate maintained at 600~700 ℃, a second round of scratching is performed on the restricted subsurface structure control layer formed in step S2 using a diamond indenter with a catalytic layer. The total scratching depth is 0.5~5 nm to catalyze the restricted subsurface structure control layer. S4. The working space is purged with inert gas to remove residual hydrogen and re-form a protective atmosphere. Then, the single crystal diamond substrate is subjected to cooling annealing treatment at a cooling rate of 20~40℃ / min, so that the scratched area that has undergone the first round of scratching and the superimposed second round of scratching will preferentially undergo local phase transition and be converted into graphene in situ. S5. Remove the catalytic material remaining on the single-crystal diamond substrate to obtain a single-crystal diamond / graphene heterojunction.
2. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 1, characterized in that, In step S2, the parameters for the first round of scrubbing are: performed at room temperature, scrubbing pressure of 100~500 mN, scanning speed of 1~10 μm / s, and number of scans of 5~30.
3. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 1, characterized in that, In step S3, the catalyst layer is a Ni / Cu composite metal catalyst layer, with a molar ratio of Ni to Cu ranging from 7:3 to 6:4, and a thickness of 100 to 200 nm.
4. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 3, characterized in that, The Ni / Cu composite metal catalyst layer was prepared by magnetron sputtering with a sputtering time of 20-40 min, a sputtering power of 100-150 W, and a working pressure of 0.4-1.1 Pa.
5. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 1, characterized in that, In step S3, the parameters for the second round of scrubbing are: scrubbing pressure of 500~800 mN, scanning speed of 1~10 μm / s, and number of scans of 30~50.
6. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 1, characterized in that, In step S2 and / or step S3, the diamond indenter is a conical indenter or a Berkovich indenter, and the equivalent radius of curvature of the tip of the diamond indenter is 1~5 μm.
7. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 1, characterized in that, In steps S2 and / or S4, the inert gas is argon, nitrogen, or helium.
8. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 1, characterized in that, In step S5, the method for removing the residual catalyst material on the single-crystal diamond substrate is to clean the residual catalyst material with dilute nitric acid, dilute hydrochloric acid, or dilute sulfuric acid.
9. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 1, characterized in that, The single-crystal diamond substrate is either a (100)-plane single-crystal diamond substrate or a (111)-plane single-crystal diamond substrate.
10. The method for preparing a single-crystal diamond / graphene heterojunction according to claim 1, characterized in that, The single-crystal diamond / graphene heterojunction comprises a single layer of graphene or 2 to 10 layers of graphene.