Graphene nanoribbons embedded between two-dimensional material layers and preparation method thereof

Abstract

The present invention provides a graphene nanoribbon embedded between two-dimensional material layers and a preparation method thereof. The structure of the graphene nanoribbon includes: a substrate with atomic-level flatness, formed by sequentially parallel stacking of at least two atomic layers, and the adjacent two atomic layers are bonded by van der Waals forces; at least one longitudinal section formed by extending the substrate by one or more atomic layer thicknesses along the thickness direction of the substrate from the substrate surface; at least one graphene nanoribbon that breaks through the van der Waals forces between any two adjacent atomic layers exposed at the longitudinal section and is embedded between the two atomic layers and encapsulated by the substrate material. The formed graphene nanoribbon is embedded in a substrate with atomic-level flatness and isolated from the external environment, enabling the graphene nanoribbon to have physical properties close to those of intrinsic nanoribbons and a regular edge structure; in addition, the preparation method is simple to operate, has a low cost, and can be mass-produced, having good industrialization value.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical material synthesis, and particularly relates to a graphene nanoribbon embedded between two-dimensional material layers and a preparation method thereof. Background Art

[0002] In recent years, graphene nanoribbons, as one-dimensional materials, have attracted extensive attention. The special energy band structure of graphene nanoribbons endows them with unique electrical, magnetic, and optical properties. Graphene nanoribbons show great application prospects in field-effect transistors, gas sensing, photodetectors, energy storage, etc.

[0003] Graphene nanoribbons are graphene strips with widths ranging from several nanometers to dozens of nanometers. They not only inherit most of the excellent properties of graphene but also have physical properties such as tunable bandgaps, spin-polarized edge states, and edge magnetotransport, which are very suitable for constructing high-performance carbon-based electronic devices. Currently, the commonly used preparation methods of graphene nanoribbons are mainly divided into two categories: the first is the top-down method, which cuts large-area graphene into nanoribbons through micro-nano processing technology; the second is the bottom-up method, which uses chemical synthesis technology to catalytically synthesize graphene nanoribbons from carbon-containing small molecules. The first category is limited by processing accuracy, and the edge structures of the prepared graphene nanoribbons are disordered, thus losing the intrinsic properties of the nanoribbons; in addition, the energy gap of the nanoribbons is too small to be suitable for fabricating field-effect transistors. Although the second method can obtain ultra-narrow graphene nanoribbons on the substrate surface, the graphene nanoribbons are exposed to high temperatures and high-energy particles during the growth process, resulting in some defects still existing in the graphene nanoribbons, and the structure of the graphene nanoribbons may be further damaged during the subsequent device processing. In summary, the graphene nanoribbons prepared by the existing methods are difficult to meet the requirements for preparing high-performance carbon-based electronic devices. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a graphene nanoribbon embedded between two-dimensional material layers and a preparation method thereof, so as to solve the problems such as disordered boundary morphology and defects of the graphene nanoribbons obtained by the existing methods for preparing graphene nanoribbons.

[0005] To achieve the above object and other related objects, the present invention provides a graphene nanoribbon embedded between two-dimensional material layers, and the graphene nanoribbon includes:

[0006] A substrate with atomic-level flatness, which is formed by sequentially and parallelly stacking at least two atomic layers, and the adjacent two atomic layers are bonded by van der Waals forces;

[0007] At least one longitudinal section is formed on the substrate by extending one or more atomic layer thicknesses along the substrate thickness direction from the substrate surface;

[0008] At least one graphene nanoribbon breaks through the van der Waals force between any two adjacent atomic layers exposed by the longitudinal section and is embedded between the two atomic layers, and is encapsulated by the substrate.

[0009] Optionally, all the graphene nanoribbons are located between the same two atomic layers or at least two graphene nanoribbons are located between different two atomic layers.

[0010] Optionally, all the graphene nanoribbons have a parallel or 60° or 120° regular arrangement morphology.

[0011] Optionally, the substrate includes a hexagonal boron nitride substrate, a graphite substrate, a mica substrate, a molybdenum disulfide substrate, an indium selenide substrate, or a chromium oxychloride substrate.

[0012] The present invention also provides a method for preparing graphene nanoribbons embedded between two-dimensional material layers. The preparation method is used to prepare the graphene nanoribbons embedded between two-dimensional material layers as described in any one of the above, and includes the following steps:

[0013] Provide a substrate with atomic-level flatness, which is formed by sequentially stacking at least two atomic layers in parallel, and the adjacent two atomic layers are combined by van der Waals force, and at least one longitudinal section is formed on the substrate, and the longitudinal section extends along the substrate thickness direction from the substrate surface;

[0014] Form nano-catalyst particles on the surface of the substrate and the surface of the longitudinal section, and make the nano-catalyst particles combine with the surface of the substrate and the surface of the longitudinal section;

[0015] Growth process: Perform a chemical vapor deposition process on the substrate with the nano-catalyst particles to form a carbon product layer on the surface of the substrate and form graphene nanoribbons inside the substrate. The graphene nanoribbons break through the van der Waals force between any two adjacent atomic layers exposed by the longitudinal section and are embedded between the two atomic layers, and are covered and encapsulated by the substrate, wherein the reaction gas introduced is a carbon source gas, and the growth temperature is 600°C to 1000°C;

[0016] Cooling process: After the growth is completed, turn off the carbon source gas, and under the action of a protective gas, cool to room temperature and take out;

[0017] Etching process: Remove the carbon product layer formed on the surface of the substrate during the growth process, so as to form only the graphene nanoribbons inside the substrate.

[0018] Optionally, the method for forming the longitudinal section includes: providing a base wafer and preparing the substrate on the base wafer by mechanical exfoliation, wherein the outer peripheral section in the thickness direction of the substrate forms the longitudinal section; or, first providing a base wafer, then preparing a substrate thin film on the base wafer by mechanical exfoliation, and then preparing the longitudinal section with a preset shape on the substrate thin film through a photolithography process and a reactive ion etching process; or, first providing a base wafer, then preparing a substrate thin film on the base wafer by mechanical exfoliation, then forming an etchant thin film on the substrate thin film, and finally etching the substrate thin film based on the etchant thin film under the condition of introducing a reaction gas and at a temperature of 800°C to 1200°C to form the substrate, wherein the section formed after etching the substrate thin film and the outer peripheral section in the thickness direction of the substrate thin film form the longitudinal section.

[0019] Optionally, the method for forming the nano-catalyst particles includes: first, forming a nano-catalyst thin film on the surface of the substrate and the surface of the longitudinal section; then, performing a heating process to heat the substrate with the nano-catalyst thin film formed thereon, so that the nano-catalyst thin film agglomerates to form the nano-catalyst particles, and at the same time moves and combines with the surface of the substrate and the surface of the longitudinal section.

[0020] Optionally, the nano-catalyst particles are one of metal nano-catalyst particles, alloy nano-catalyst particles and metal oxide nano-catalyst particles that are eutectic with carbon.

[0021] Optionally, the carbon source gas includes at least one of methane, acetylene and ethanol.

[0022] Optionally, the chemical vapor deposition process is a furnace tube process, and during the growth process, hydrogen is introduced into the furnace tube at the same time.

[0023] As described above, the graphene nanoribbons embedded between two-dimensional material layers and the preparation method thereof according to the present invention form graphene nanoribbons embedded in a substrate with atomic-level flatness, isolated from the external environment, so that the graphene nanoribbons have physical properties close to those of intrinsic nanoribbons, with better quality. At the same time, the edge structure of the graphene nanoribbons is regular; in addition, the preparation method is simple, the cost is low, and it can be mass-produced, having better industrialization value. Description of the Drawings

[0024] Figure 1 It shows a schematic diagram of the growth device used in the preparation process of the graphene nanoribbons embedded between two-dimensional material layers according to the present invention.

[0025] Figure 2 It shows a schematic structural diagram of an example of the graphene nanoribbons embedded between two-dimensional material layers according to the present invention.

[0026] Figure 3 A schematic structural diagram showing another example of the graphene nanoribbon embedded between two-dimensional material layers of the present invention.

[0027] Figure 4 A top view of a scanning electron microscope of the graphene nanoribbon embedded between two-dimensional material layers of the present invention, with a scale bar of 10 μm.

[0028] Figure 5 A cross-sectional view of a scanning transmission electron microscope (STEM) of the graphene nanoribbon embedded between two-dimensional material layers of the present invention, with a scale bar of 2 nm.

[0029] Description of component labels

[0030] 10 Heating furnace

[0031] 11 Furnace tube

[0032] 12 Substrate

[0033] 13 Longitudinal section

[0034] 14 Graphene nanoribbon

[0035] 15 Catalyst particle

[0036] 16 Gas Detailed implementation manners

[0037] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] When detailing the embodiments of the present invention, for the sake of convenience of description, the cross-sectional views showing the device structure will be enlarged locally in a non-general proportion, and the schematic diagrams are only examples and should not limit the scope of protection of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0039] For ease of description, spatially relative terms such as "below", "beneath", "lower", "under", "above", "upper", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more intervening layers. As used herein, "between... and..." means including the endpoint values.

[0040] In the context of the present application, the structure in which the first feature is "above" the second feature as described may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0041] Please refer to Figures 1 to 5 . It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present invention. Therefore, only the components related to the present invention are shown in the illustrations, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0042] Embodiment 1

[0043] As Figures 1 to 5 shown, this embodiment provides a graphene nanoribbon embedded between two-dimensional material layers. The graphene nanoribbon includes:

[0044] A substrate 12 with atomic-level flatness, which is formed by sequentially stacking at least two atomic layers in parallel, and the adjacent two atomic layers are bonded by van der Waals forces. Here, it should be noted that the specific atomic layers are not shown in the figure;

[0045] At least one longitudinal section 13, which is formed by extending one or more atomic layer thicknesses of the substrate 12 along the thickness direction of the substrate 12 from the surface of the substrate 12;

[0046] At least one graphene nanoribbon 14, which breaks through the van der Waals forces of any two adjacent atomic layers exposed by the longitudinal section 13 and embeds between the two atomic layers, and is covered and encapsulated by the substrate 12.

[0047] Here, it should be noted that for ease of understanding the structure of the graphene nanoribbon embedded between two-dimensional material layers in this embodiment, Figure 2 and Figure 3 only a few graphene nanoribbons are schematically shown, and actually there will be a structure of several graphene nanoribbons in the substrate.

[0048] The graphene nanoribbons embedded between the two-dimensional material layers in this embodiment are embedded in a substrate with atomic-level flatness and isolated from the external environment, enabling the graphene nanoribbons to have physical properties close to those of intrinsic nanoribbons and better quality.

[0049] As an example, as Figure 2 and Figure 3 shown, all the graphene nanoribbons 14 are located between the same two atomic layers or at least two of the graphene nanoribbons 14 are located between different two atomic layers. That is, it is not restricted whether the horizontal heights of all the graphene nanoribbons 14 in the substrate 12 are the same. They can all be between the same two atomic layers, or all be between different two atomic layers, or some can be between the same two atomic layers and some can be between different two atomic layers. That is to say, there can be no atomic layer between the graphene nanoribbons 14, or there can be one or more atomic layers in between.

[0050] As a preferred example, as Figure 4 and Figure 5 shown, all the graphene nanoribbons 14 have a parallel or 60° or 120° regular arrangement morphology. They have a neat edge structure of the graphene nanoribbons, with lengths ranging from dozens of μm to hundreds of μm, relatively narrow widths and a wide range, approximately from 1 nm to 10 nm.

[0051] As another preferred example, the substrate 12 is selected as a substrate with atomic-level flatness, such as, for example, a hexagonal boron nitride substrate, a graphite substrate, a mica substrate, a molybdenum disulfide substrate, an indium selenide substrate, a chromyl chloride substrate, and so on.

[0052] As an example, the longitudinal section 13 can be a longitudinal section naturally formed on the outer peripheral section in the thickness direction of the substrate 12; or it can be a longitudinal section formed by etching the substrate 12 along its thickness direction. It is specifically set according to actual needs.

[0053] Embodiment 2

[0054] This embodiment provides a preparation method for graphene nanoribbons embedded between two-dimensional material layers. This preparation method can be used to prepare the graphene nanoribbons embedded between two-dimensional material layers described in Embodiment 1 above. For the effects of the prepared graphene nanoribbons, please refer to Embodiment 1 above, which will not be elaborated below. The preparation method includes the following steps:

[0055] Provide a substrate with atomic-level flatness, which is formed by sequentially stacking at least two atomic layers in parallel. The adjacent two atomic layers are bonded by van der Waals forces, and at least one longitudinal section is formed on the substrate, and the longitudinal section extends from the substrate surface along the substrate thickness direction;

[0056] Form nano-catalyst particles on the surface of the substrate and the surface of the longitudinal section, and bond the nano-catalyst particles to the surface of the substrate and the surface of the longitudinal section;

[0057] Growth process: Perform a chemical vapor deposition process on the substrate with the nano-catalyst particles to form a carbon product layer on the surface of the substrate and form graphene nanoribbons inside the substrate. The graphene nanoribbons break through the van der Waals force between any two adjacent exposed atomic layers on the longitudinal section and are embedded between the two atomic layers, and are covered and encapsulated by the substrate. The reaction gas introduced is a carbon source gas, and the growth temperature is 600°C to 1000°C;

[0058] Cooling process: After the growth is completed, turn off the carbon source gas, and under the action of the protective gas, cool it to room temperature and take it out;

[0059] Etching process: Remove the carbon product layer formed on the surface of the substrate during the growth process, so that only the graphene nanoribbons are formed inside the substrate.

[0060] In the preparation method of the graphene nanoribbons embedded between two-dimensional material layers in this embodiment, the formation mechanism of the graphene nanoribbons is as follows: First, bond the nano-catalyst particles to the surface of the longitudinal section. During the growth process, at a growth temperature of 600°C to 1000°C, the carbon source gas is cracked with the assistance of the nano-catalyst particles and releases carbon atoms and carbon-containing radicals. When the carbon content in the nano-catalyst particles on the surface of the longitudinal section reaches a certain supersaturation, it will precipitate and nucleate from the nano-catalyst particles, break through the van der Waals force between two adjacent atomic layers and intercalate into the substrate with atomic-level flatness, so as to grow between the atomic layers of the substrate, that is, between the two-dimensional substrate material layers. Finally, remove the carbon product layer formed on the surface of the substrate. The graphene nanoribbons prepared by this method are embedded inside the substrate and are not exposed on the surface of the substrate, making the graphene nanoribbons have physical properties close to those of intrinsic nanoribbons. At the same time, the edge structure of the graphene nanoribbons is regular; in addition, the preparation method is simple, the cost is low, and it can be mass-produced, having better industrialization value.

[0061] As Figures 1 to 3 shown, the preparation method of this embodiment will be described in detail below with reference to the accompanying drawings.

[0062] As Figure 1 shown, first perform step S1 to provide a substrate 12 with atomic-level flatness. The substrate 12 is formed by stacking at least two atomic layers in parallel in sequence. The adjacent two atomic layers are bonded by van der Waals force, and at least one longitudinal section 13 is formed on the substrate 12. The longitudinal section 13 extends from the surface of the substrate 12 along the thickness direction of the substrate 12.

[0063] For ease of understanding, Figure 1 only a longitudinally etched cross-section 13 is shown in Figure 1 . Those skilled in the art can understand that, in practice, several longitudinally etched cross-sections 13 can be formed on the substrate 12 according to actual needs. The depths of the several longitudinally etched cross-sections 13 can be the same or different, and no excessive restrictions are imposed here.

[0064] As an example, the substrate 12 can be any suitable substrate with atomic-level flatness, such as a hexagonal boron nitride substrate, a graphite substrate, a mica substrate, a molybdenum disulfide substrate, an indium selenide substrate, a chromium oxychloride substrate, etc.

[0065] As an example, the method for forming the longitudinally etched cross-section 13 can be: providing a base wafer, and preparing the substrate 12 on the base wafer by mechanical exfoliation, where the outer peripheral cross-section in the thickness direction of the substrate 12 forms the longitudinally etched cross-section 13 (as Figure 2 shown in Figure 3 ); or, first providing a base wafer, then preparing a substrate thin film on the base wafer by mechanical exfoliation, then forming an etchant thin film on the substrate thin film, and finally etching the substrate thin film based on the etchant thin film at a temperature of 800 °C to 1200 °C while introducing a reaction gas to form the substrate 12, where the cross-section formed after etching the substrate thin film and the outer peripheral cross-section in the thickness direction of the substrate thin film form the longitudinally etched cross-section 13; or first providing a base wafer, then preparing a substrate thin film on the base wafer by mechanical exfoliation, and then preparing the longitudinally etched cross-section 13 with a preset shape on the substrate thin film through a photolithography process and a reactive ion etching process, where the photolithography process can be selected as ultraviolet lithography or EBL, etc.

[0066] As Figure 1 shown in

[0067] Then, step S2 is performed to form nano-catalyst particles 15 on the surfaces of the substrate 12 and the longitudinally etched cross-section 13, and to bond the nano-catalyst particles 15 to the surfaces of the substrate 12 and the longitudinally etched cross-section 13.

[0068] As a specific example, the method for forming the nano-catalyst particles 15 includes: First, a nano-catalyst thin film is formed on the surface of the substrate 12 and the surface of the longitudinal section 13, that is, a nano-catalyst thin film is formed on the entire exposed surface of the substrate 12 that needs to be deposited subsequently. The nano-catalyst thin film can be deposited by evaporation coating, spin coating or dip coating methods; then, a heating process is carried out, and the substrate 12 formed with the nano-catalyst thin film is heated to cause the nano-catalyst thin film to agglomerate to form the nano-catalyst particles 15, and at the same time move and combine with the surface of the substrate 12 and the surface of the longitudinal section 13. During this heating process, the nano-catalyst thin film will agglomerate at high temperature to form nano-catalyst particles, and at the longitudinal section 13, the nano-catalyst particles will combine with the substrate here.

[0069] As a preferred example, the process of forming the nano-catalyst particles 15 can be formed in a tube furnace, and the tube furnace is in the form of a heating furnace 10 outside the furnace tube 11. This form can provide good sealing, heat preservation box and temperature control stability. During the heating process, the substrate 12 is placed in the furnace tube 11 for the heating process. Preferably, the furnace tube 11 is a quartz furnace tube. More preferably, during this heating process, a gas 16 of hydrogen and argon is introduced into the furnace tube 11 as a protective gas and can also be used as a reducing gas to facilitate the reduction of oxidized nano-catalyst particles and some carbon-containing impurity substances generated by the carbon source gas during the subsequent high-temperature growth process, and the flow rate of the carbon source gas introduced during the subsequent growth process is the same as the flow rate of argon during the heating process to ensure the stability of the total gas flow rate during the growth process and ensure the growth quality of the graphene nanoribbons.

[0070] As Figure 2 and Figure 3 As shown, then step S3 is carried out, the growth process: a chemical vapor deposition process is carried out on the substrate 12 with the nano-catalyst particles 15 to form graphene nanoribbons 14 inside the substrate 12. The graphene nanoribbons 14 break through the van der Waals force between any two adjacent atomic layers exposed on the longitudinal section 13 and are embedded between the two atomic layers and encapsulated by the substrate 12. The reaction gas introduced is a carbon source gas, and the growth temperature is 600 °C to 1000 °C.

[0071] As an example, the process of forming the nano-catalyst particles 15 and this growth process can both be formed in the same tube furnace, that is, both adopt the furnace tube process, so as to make the preparation process achieve consistent coherence to improve the preparation quality and efficiency. At this time, during the growth process, the continuous introduction of hydrogen as a protective gas is maintained, the introduction of argon as a protective gas is stopped, and then it is replaced with a carbon source gas, and the flow rate of the carbon source gas is the same as the flow rate of the argon protective gas to ensure the stability of the total gas flow rate during the heating process and the growth process.

[0072] As an example, the carbon source gas is selected from gases containing carbon elements, such as methane, acetylene, ethanol, etc. It can be a single gas or a mixture of several gases.

[0073] Next, step S4 is carried out, the cooling process: after the growth is completed, the carbon source gas is closed, and under the action of the protective gas, it is cooled to room temperature and taken out.

[0074] As a specific example, in this cooling process, the carbon source gas is closed, and hydrogen and argon are replaced and continue to be introduced as the protective gas, and the flow rates of the hydrogen and the argon are the same as those in the heating process, and it is naturally cooled to room temperature. Similarly, the stability of the total gas flow rate is ensured throughout the cooling process.

[0075] Finally, step S5 is carried out, the etching process: the carbon product layer formed on the surface of the substrate 12 during the growth process is removed, so that the graphene nanoribbons are only formed inside the substrate 12.

[0076] It should be noted here that the carbon product layer formed on the surface of the substrate 12 generally includes graphene nanoribbons, graphene, carbon nanotubes, amorphous carbon, etc.

[0077] The following further illustrates the preparation method of the graphene nanoribbons embedded between two-dimensional material layers in this embodiment through specific experimental examples.

[0078] Experimental Example 1

[0079] 1) Take a silicon wafer with a 300-nm-thick oxide layer on the surface and cut it into 1 cm × 1 cm small pieces.

[0080] 2) Prepare a hexagonal boron nitride (hBN) thin sheet with various-shaped longitudinal sections on the above silicon wafer by mechanical exfoliation method, where the longitudinal section is a longitudinal section naturally formed by the outer peripheral section of the hexagonal boron nitride along the thickness direction.

[0081] 3) Use the method of thermal evaporation coating to deposit a thin film of iron nanoparticle catalyst with a thickness of

[0082] 4) Place the above silicon wafer coated with the catalyst in a tube furnace. During the heating process, the gas atmosphere in the furnace is hydrogen with a flow rate of 50 SCCM and argon with a flow rate of 100 SCCM. The heating process takes about 15 minutes and gradually rises from room temperature to the growth temperature of 850 °C. The air pressure is maintained at 1 standard atmosphere during the heating process.

[0083] 5) After the temperature reaches the target growth temperature of 850 °C, stop introducing argon. On the basis of maintaining the original hydrogen flow rate of 50 SCCM unchanged, introduce an additional 100 SCCM of methane gas as the growth gas and grow for 10 minutes at 850 °C. During the growth process, maintain the pressure at 1 standard atmosphere.

[0084] 6) After the growth is completed, turn off the methane gas, allow it to cool naturally to room temperature, and then take out the sample.

[0085] 7) Place the grown sample into the PECVD system, evacuate it, introduce hydrogen with a flow rate of 30 SCCM, heat it to 300 °C, and treat the sample with a plasma of 30 W for 1 hour to etch away impurity carbon products such as graphene nanoribbons, carbon nanotubes, and amorphous carbon growing on the surface of the sample, leaving only the graphene nanoribbons between the hexagonal boron nitride layers.

[0086] Experimental Example 2

[0087] 1) Take a silicon wafer with a 300-nm-thick oxide layer on its surface and cut it into small pieces of 1 cm × 1 cm.

[0088] 2) Prepare a hexagonal boron nitride (hBN) thin film on the above silicon wafer by mechanical exfoliation method. At this time, no longitudinal section is formed in the hexagonal boron nitride thin film.

[0089] 3) Use the method of electron beam evaporation coating to deposit a nickel thin film with a certain thickness on the above hexagonal boron nitride thin film material as an etchant.

[0090] 4) Etch the surface of the hexagonal boron nitride thin film in an environment with a hydrogen-to-argon flow ratio of 1:1 and a temperature of 1000 °C to form various longitudinal sections in the hexagonal boron nitride thin film.

[0091] 5) Use the method of thermal evaporation coating to deposit a cobalt nanoparticle catalyst thin film with a certain thickness on the above hexagonal boron nitride thin film with longitudinal sections as a growth catalyst.

[0092] 6) Place the above silicon wafer with the catalyst in a heating furnace, evacuate the air in the furnace, then introduce hydrogen and acetylene gases with a flow ratio of 1:1, gradually raise the temperature of the heating furnace from room temperature to 750 °C. The heating process takes about 10 minutes, and maintain the pressure at 1 standard atmosphere during the heating process.

[0093] 7) After the temperature reaches the target growth temperature of 750 °C, keep the temperature and pressure stable and grow for 30 min.

[0094] 8) After the growth is completed, evacuate the remaining gas in the furnace, introduce argon and hydrogen as protective gases, allow it to cool naturally to room temperature, and then take out the sample.

[0095] 9) Place the grown sample into the PECVD system, evacuate the air, introduce hydrogen with a flow rate of 30 SCCM, heat it to 300 °C, and treat the sample with plasma at a power of 30 W for 1 hour to etch away the impurity carbon products such as graphene nanoribbons, carbon nanotubes, and amorphous carbon grown on the substrate surface, leaving only the graphene nanoribbons between the hexagonal boron nitride layers.

[0096] In summary, the present invention provides a graphene nanoribbon embedded between two-dimensional material layers and a preparation method thereof. The graphene nanoribbon is embedded in a substrate with atomic-level flatness and isolated from the external environment, enabling the graphene nanoribbon to have physical properties close to those of intrinsic nanoribbons, with better quality. At the same time, the edge structure of the graphene nanoribbon is regular. In addition, the preparation method is simple, with low cost, and can be mass-produced, having good industrialization value. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0097] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A graphene nanoribbon embedded between two-dimensional material layers, characterized in that, the graphene nanoribbon embedded between two-dimensional material layers includes: a substrate with atomic-level flatness, which is formed by sequentially parallel stacking of at least two atomic layers, and the adjacent two atomic layers are bonded by van der Waals forces; at least one longitudinal section formed by extending the substrate by one or more atomic layer thicknesses along the substrate thickness direction from the substrate surface; at least one graphene nanoribbon that breaks through the van der Waals forces between any two adjacent atomic layers exposed by the longitudinal section and embeds between the two atomic layers, and is encapsulated by the substrate.

2. The graphene nanoribbon embedded between two-dimensional material layers according to claim 1, characterized in that: all the graphene nanoribbons are located between the same two atomic layers or at least two graphene nanoribbons are located between different two atomic layers.

3. The graphene nanoribbon embedded between two-dimensional material layers according to claim 1, characterized in that: all the graphene nanoribbons have a parallel or 60° or 120° regular arrangement morphology.

4. The graphene nanoribbon embedded between two-dimensional material layers according to claim 1, characterized in that: the substrate includes a hexagonal boron nitride substrate, or a graphite substrate, or a mica substrate, or a molybdenum disulfide substrate, or an indium selenide substrate, or a chromium oxychloride substrate.

5. A preparation method of a graphene nanoribbon embedded between two-dimensional material layers, characterized in that, the preparation method is used to prepare the graphene nanoribbon embedded between two-dimensional material layers as described in any one of claims 1 to 4, and includes the following steps: providing a substrate with atomic-level flatness, which is formed by sequentially parallel stacking of at least two atomic layers, the adjacent two atomic layers are bonded by van der Waals forces, and at least one longitudinal section is formed on the substrate, and the longitudinal section extends along the substrate thickness direction from the substrate surface; forming nano-catalyst particles on the substrate surface and the longitudinal section surface, and making the nano-catalyst particles combine with the substrate surface and the longitudinal section surface; Growth process: performing a chemical vapor deposition process on the substrate with the nano-catalyst particles to form a carbon product layer on the substrate surface and form graphene nanoribbons inside the substrate, the graphene nanoribbons break through the van der Waals forces between any two adjacent atomic layers exposed by the longitudinal section and embed between the two atomic layers, and are encapsulated by the substrate, wherein the reaction gas introduced is a carbon source gas, and the growth temperature is 600°C to 1000°C; Cooling process: after the growth is completed, closing the carbon source gas, and cooling to room temperature and taking out under the action of a protective gas; Etching process: removing the carbon product layer formed on the substrate surface during the growth process, so as to form only the graphene nanoribbons inside the substrate.

6. The preparation method of the graphene nanoribbon embedded between two-dimensional material layers according to claim 5, characterized in that, The method for forming the longitudinal section includes: providing a base wafer and preparing the substrate on the base wafer by mechanical exfoliation, wherein the outer peripheral section in the thickness direction of the substrate forms the longitudinal section; or, first providing a base wafer, then preparing a substrate thin film on the base wafer by mechanical exfoliation, then forming an etchant thin film on the substrate thin film, and finally etching the substrate thin film based on the etchant thin film at a temperature of 800 °C to 1200 °C while introducing a reaction gas, to form the substrate, wherein the section formed after etching the substrate thin film and the outer peripheral section in the thickness direction of the substrate thin film form the longitudinal section; or, first providing a base wafer, then preparing a substrate thin film on the base wafer by mechanical exfoliation, and then preparing the longitudinal section with a preset shape on the substrate thin film through a photolithography process and a reactive ion etching process.

7. The method for preparing graphene nanoribbons embedded between two-dimensional material layers according to claim 5, characterized in that, the method for forming the nano-catalyst particles includes: first, forming a nano-catalyst thin film on the surface of the substrate and the surface of the longitudinal section; then, during a heating process, heating the substrate formed with the nano-catalyst thin film, so that the nano-catalyst thin film agglomerates to form the nano-catalyst particles, and at the same time moves and combines with the surface of the substrate and the surface of the longitudinal section.

8. The method for preparing graphene nanoribbons embedded between two-dimensional material layers according to claim 5, characterized in that: the nano-catalyst particles are one of metal nano-catalyst particles, alloy nano-catalyst particles and metal oxide nano-catalyst particles that are eutectic with carbon.

9. The method for preparing graphene nanoribbons embedded between two-dimensional material layers according to claim 5, characterized in that: the carbon source gas includes at least one of methane, acetylene and ethanol.

10. The method for preparing graphene nanoribbons embedded between two-dimensional material layers according to claim 5, characterized in that: the chemical vapor deposition process is a furnace tube process, and during the growth process, hydrogen is introduced into the furnace tube at the same time.

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