A method for preparing a hexagonal boron nitride / graphene / hexagonal boron nitride multilayer heterojunction material

Abstract

This invention relates to the field of two-dimensional material preparation, specifically a method for preparing a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterojunction material. Using high-quality few-layer or multi-layer graphene, based on the principle of substitution reaction, a specific number of graphene layers on the top and bottom surfaces are converted into hexagonal boron nitride, while retaining high-quality graphene in the middle layer, thereby forming a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterojunction material with a specific number of layers and stacking order. The hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterojunction material prepared by this method has a middle layer of graphene with high crystallinity and is not in contact with the external environment, ensuring a clean interface between the hexagonal boron nitride / graphene layers. This lays the foundation for achieving graphene encapsulation and thus significantly improving its electrical, thermal, and chemical properties.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation technology of a two-dimensional material laminated heterostructure, in particular to a preparation method of a hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material, which is suitable for preparing a large-area, high-quality, and completely clean and pollution-free hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material. BACKGROUND

[0002] Hexagonal boron nitride is an excellent insulating substrate with a wide band gap. Due to the characteristics of atomic-level flatness, no dangling bonds or charge impurities on the surface, it can effectively isolate the charge doping of the underlying substrate material as a dielectric layer, so that the high mobility and unique electronic structure of graphene can be maintained. The preparation of hexagonal boron nitride by mechanical exfoliation is limited by the small exfoliation size and uncontrollable thickness. Chemical vapor deposition has become the main method for preparing high-quality large-area hexagonal boron nitride.

[0003] Due to the small thickness of single-layer hexagonal boron nitride, it is difficult to effectively protect two-dimensional materials from the influence of the substrate and the environment. In contrast, multi-layer hexagonal boron nitride is a more suitable substrate for maintaining the inherent properties of two-dimensional materials such as graphene. The preparation procedure of the hexagonal boron nitride / graphene / hexagonal boron nitride vertical heterojunction prepared by the transfer method is complex, the interface is easily contaminated, and it is difficult to mass-produce. The current research on large-area high-quality graphene / hexagonal boron nitride vertical heterojunction mainly focuses on chemical vapor deposition technology. The preparation of laminated heterostructures by chemical vapor deposition requires layer-by-layer growth, which makes it difficult to obtain high-quality graphene and surface hexagonal boron nitride. Therefore, it is still extremely challenging to prepare high-quality hexagonal boron nitride / graphene / hexagonal boron nitride with a clean interface. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of high-quality hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material with a specific stacking order. This method converts part of the whole graphene into hexagonal boron nitride to form a laminated heterostructure, which has the outstanding characteristics of high-quality graphene and completely clean interface. Therefore, it can be used as a preparation method of high-quality hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material with a specific stacking order.

[0005] The technical solution of the present application is:

[0006] A preparation method of hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material, which uses high-quality few-layer or multi-layer graphene, and converts the specified number of graphene layers on the upper and lower surfaces into hexagonal boron nitride by chemical reaction replacement, thereby forming hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material stacked in turn.

[0007] The preparation method of the hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material uses high-quality graphene prepared by a peeling method, a chemical vapor deposition method, a silicon carbide pyrolysis method, or an epitaxial method.

[0008] The preparation method of the hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material uses a precursor for chemical reaction replacement, which is a reactant for preparing hexagonal boron nitride, including but not limited to ammonia and boric acid, aminoborane, ammonia and sodium tetraborate, ammonia and sodium metaborate, nitrogen and sodium tetraborate.

[0009] The preparation method of the hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material has the following preparation process of the hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material:

[0010] 1) First stage: high-quality few-layer or multi-layer graphene is first prepared on an initial substrate; for the initial growth substrate that chemically reacts with the precursor for preparing hexagonal boron nitride, the prepared graphene is transferred from the initial growth substrate to an inert substrate;

[0011] 2) Second stage: the graphene on the initial substrate is placed in a high-temperature chemical reaction chamber, and a precursor for preparing hexagonal boron nitride is introduced at a high temperature to replace the surface layer of the graphene, and a typical heating temperature is 300-600°C; the degree of replacement reaction on the surface of the graphene is controlled by controlling the reaction time, so as to form a hexagonal boron nitride / graphene vertical heterojunction with a specific layer number and stacking order;

[0012] 3) Third stage: the prepared hexagonal boron nitride / graphene vertical heterojunction is transferred to a secondary substrate, so that the bottom graphene is exposed to the upper side, and then the operation steps of the second stage are repeated to obtain a hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material; the layer number of graphene and hexagonal boron nitride in the laminated heterostructure is controlled by changing the layer number of the initial graphene and the degree of replacement reaction.

[0013] The preparation method of the hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material, in the second stage, the precursor for preparing hexagonal boron nitride is directly placed on the surface of the graphene, or is in contact with the graphene by direct evaporation or by being carried by a carrier gas; for the latter two ways, the precursor needs to be heated to 300-600°C to form a high enough concentration.

[0014] The preparation method of the hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material, in order to promote the graphene reaction to be replaced by hexagonal boron nitride, defects are generated on the surface layer of graphene by ion beam bombardment, plasma etching or chemical functionalization etching method before the second stage, thereby providing a channel for the subsequent replacement process, so that the reaction of replacing graphene by hexagonal boron nitride is more likely to occur.

[0015] The preparation method of the hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material can obtain a defect-containing graphene surface layer with different thicknesses on the original high-quality graphene by adjusting the intensity or time of etching.

[0016] The preparation method of the hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material, in the process of replacing the surface layer graphene with hexagonal boron nitride, the defect-containing graphene will gradually change into hexagonal boron nitride as the replacement reaction time is prolonged, and since the graphene that is not etched has high quality and has an isolation effect on the reactant precursor, the replacement reaction will eventually stop after the defect-containing graphene layer is completely converted into hexagonal boron nitride.

[0017] The design idea of the present application is:

[0018] The present application adopts high-quality multilayer graphene as the precursor material of the whole laminated heterostructure, and converts the specific number of layers on the upper and lower surfaces of the multilayer graphene into hexagonal boron nitride based on the replacement reaction, while retaining the intrinsic structure of the high-quality graphene in the middle layer, thereby forming a high-quality and clean-interface hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material.

[0019] The characteristics and beneficial effects of the present application are:

[0020] 1. The hexagonal boron nitride / graphene / hexagonal boron nitride laminated heterojunction material prepared by the method has high crystalline quality of the graphene in the middle layer and the hexagonal boron nitride on the surface layer, and the graphene is not in contact with the outside world, thereby ensuring a clean interface between the hexagonal boron nitride and the graphene.

[0021] 2. The method has high controllability, and in the process of replacing the defect-containing surface layer graphene with hexagonal boron nitride, the graphene in the middle layer has an isolation effect on the reactant precursor, and the replacement reaction stops automatically after the defect-containing graphene layer is completely converted into hexagonal boron nitride. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure is a schematic diagram of the device for growing high-quality multilayer graphene by high-temperature annealing and chemical vapor deposition. In the figure, 11 is a gas inlet, 12 is a reaction furnace, 13 is a high-catalytic-activity metal substrate, 14 is a sealing device, 15 is a gas outlet, and 16 is a quartz tube.

[0023] Figure 2 Schematic diagram of ion beam bombardment of high-quality graphene. In the figure, 21 is an argon gas source; 22 is a slit; 23 is a gas beam; 24 is an ionization chamber; 25 is an argon ion beam; 26 is high-quality multilayer graphene; and 27 is a SiO2 / Si substrate.

[0024] Figure 3 Schematic diagram of a device for preparing graphene / hexagonal boron nitride heterojunction and hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterojunction material. In the figure, 31 is a gas inlet; 32 is a heating belt; 33 is a quartz boat; 34 is a reaction furnace; 35 is high-quality multilayer graphene / SiO2 / Si or high-quality multilayer graphene / hexagonal boron nitride / SiO2 / Si; 36 is a sealing device; 37 is a gas outlet; and 38 is a quartz tube. DETAILED DESCRIPTION

[0025] In the specific implementation, high-quality few-layer or multilayer graphene is used, and based on the replacement reaction principle, the graphene of specific layers on the upper and lower surfaces is respectively converted into hexagonal boron nitride, while the high-quality graphene of the middle layer is reserved, thereby forming a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterojunction material with specific layer number and stacking order.

[0026] In the following, the present application is further described in detail through examples and drawings.

[0027] Example 1

[0028] Preparation of multilayer hexagonal boron nitride / single-layer graphene / multilayer hexagonal boron nitride stacked heterojunction. First, high-quality 9-layer graphene is prepared on a metal nickel foil by a chemical vapor deposition (CVD) method; as shown in FIG. 1, the graphene is transferred to a SiO2 / Si substrate to obtain a high-quality multilayer graphene / SiO2 / Si structure. Figure 1As shown, high-quality graphene is grown in a normal-pressure hot-wall chemical vapor deposition reactor. The quartz tube 16 of the reactor 12 has a gas inlet 11 and a gas outlet 15 on both sides. The central isothermal zone of the quartz tube 16 is 50 mm long, and both ends of the quartz tube 16 are sealed by a sealing device 14. A highly catalytically active metal substrate 13 (nickel foil) is placed inside the quartz tube 16 (22 mm in diameter). In the standard growth process, the nickel foil is washed with acetone, isopropanol, and deionized water before use to degrease the surface. Then, it is placed in an electrolyte solution composed of a certain proportion (330 mL deionized water, 167 mL ethanol, 167 mL orthophosphoric acid, 33 mL isopropanol, and 3.3 g urea) and electrochemically polished at a constant voltage of 8 V. The electrochemically polished nickel foil was cleaned with deionized water and ethanol, then dried with nitrogen and quickly placed in the central isothermal zone of the reactor. Under a mixed carrier gas of 300 sccm argon and 200 sccm hydrogen, the nickel foil was annealed to 1050°C for 1 hour within 30 minutes. Then, 10 sccm of methane was introduced for 5 minutes to grow nine layers of graphene on the surface of the nickel foil. After growth, the metal substrate was removed from the central isothermal zone and rapidly cooled.

[0029] A polymethyl methacrylate (PMMA) ethyl lactate solution (PMMA 4 wt%) was dropwise added to the graphene surface. A layer of PMMA was then spin-coated onto the graphene surface using a spin-coating method (spin-coating speed 2500 rpm, spin-coating time 60 seconds, spin-coating times 2). The spin-coated PMMA / graphene / nickel foil was placed on a hot plate and dried at 90°C for 10 minutes. After etching the nickel foil with a 1 mol / L ferric chloride aqueous solution, the PMMA / graphene was transferred to a SiO2 / Si substrate. The PMMA on the graphene surface was removed with acetone at 80°C. The graphene was then rinsed with isopropanol and ethanol, respectively, and dried at 120°C for 15 minutes to obtain 9 layers of graphene / SiO2 / Si.

[0030] like Figure 2 As shown, this invention employs argon ion bombardment to defect a specific number of layers on the surface of high-quality graphene. The argon ion bombardment system is sequentially configured with an argon gas source 21, a slit 22, an ionization chamber 24, high-quality multilayer graphene 26, and a SiO2 / Si substrate 27 (i.e., a silicon wafer substrate with a pre-oxidized oxide layer). Argon gas is supplied by the argon gas source 21, and a high-speed gas beam 23 is ejected from the slit 22. In the ionization chamber 24, the argon gas beam 23 is ionized into an argon ion beam 25. The ejected argon ion beam 25 defects a specified number of layers on the high-quality multilayer graphene 26 on the SiO2 / Si substrate 27. In this embodiment, "specific number of layers" refers to four graphene layers on each of the top and bottom surfaces of a nine-layer graphene system.

[0031] As Figure 3 shown, the present application uses a normal pressure hot-wall chemical vapor reaction furnace with heating belt 32 to convert multi-layer graphene into multi-layer hexagonal boron nitride / single-layer graphene / multi-layer hexagonal boron nitride stacked heterojunction. The quartz tube 38 of the reaction furnace 34 is provided with a gas inlet 31 and a gas outlet 37 on both sides, respectively, and the central constant temperature area of the quartz tube 38 is 50 mm long, and the both ends of the quartz tube 38 are sealed by sealing devices 36, and the high-quality multi-layer graphene / SiO2 / Si 35 (9 layers) is placed in the central constant temperature area of the quartz tube 38 (diameter 22 mm), and the solid boric acid is placed in the quartz boat 33 upstream of the central constant temperature area of the quartz tube 38, and the solid boric acid is heated by the heating belt 32 outside the quartz tube 38 at this position.

[0032] The preparation process of the stacked heterojunction is as follows:

[0033] 1) After the transfer of the 9-layer graphene / SiO2 / Si, it is placed in the central constant temperature area of the quartz tube (diameter 22 mm) of the reaction furnace, and about 120 mg of solid boric acid is added in the quartz boat upstream of the quartz tube. After the reaction chamber (quartz tube cavity) is pumped to vacuum and filled with argon, the internal gas pressure of the reaction chamber is maintained at about 20 Torr.

[0034] 2) The reaction furnace is heated to 1000℃ within 30 minutes, the solid boric acid precursor is heated to 300-600℃, and at the same time, the argon flow is adjusted to 250 sccm, and 50 sccm of ammonia gas is introduced, and the conversion reaction starts with the heating of the solid boric acid and the introduction of gaseous ammonia. After the conversion is completed, the reaction substrate is pushed out of the reaction area (central constant temperature area) by the push-pull rod to realize rapid cooling, and at the same time, the ammonia gas is turned off and the heating of the solid boric acid is stopped. 100 sccm of hydrogen gas is introduced to maintain the reducing atmosphere in the reaction chamber, and when the reaction chamber is cooled to room temperature, the carrier gas is turned off, and 4-layer hexagonal boron nitride / 5-layer graphene / SiO2 / Si is obtained.

[0035] 3) The PDMS stamp is pressed directly on the 4 layers of hexagonal boron nitride / 5 layers of graphene / SiO2 / Si surface, and then the SiO2 / Si substrate is removed by using a 6:1 buffered oxide etchant (BOE) solution. After the PDMS / hexagonal boron nitride / graphene is cleaned with deionized water and dried, PMMA with a thickness of 50 μιη is spin-coated on the graphene surface (spin speed of 2500 rpm, spin time of 60 seconds, and spin number of 8-10 times). After the spin coating is completed, the PMMA / graphene / hexagonal boron nitride / PDMS (PMMA facing up) is placed on a hot stage and dried at 150°C for 1 hour. After the drying is completed, the PDMS layer is directly removed. Then, the PMMA / graphene / hexagonal boron nitride is placed on a SiO2 / Si substrate, and the poly(methyl methacrylate) on the graphene surface is removed by using acetone at 80°C. The graphene is then washed with isopropyl alcohol and ethanol, respectively. After being dried at 120°C for 15 minutes, 5 layers of graphene / 4 layers of hexagonal boron nitride / SiO2 / Si are obtained.

[0036] 4) The transferred 5 layers of graphene / 4 layers of hexagonal boron nitride / SiO2 / Si is placed in the central constant temperature region of a quartz tube (diameter of 22 mm) of a reaction furnace. About 80 mg of solid boric acid is added to a quartz boat upstream of the quartz tube. After the reaction chamber is pumped to vacuum, argon is filled, and the internal gas pressure of the reaction chamber is maintained at about 20 Torr.

[0037] 5) The reaction furnace is heated to 1000°C within 30 minutes, and the solid boric acid precursor is heated to 300-600°C. At the same time, the flow rate of argon is adjusted to 270 sccm, and 30 sccm of ammonia gas is introduced. The conversion reaction starts with the heating of the solid boric acid and the introduction of gaseous ammonia. After the conversion is completed, the reaction substrate is pushed out of the reaction region by using a push-pull rod to achieve rapid cooling, and the ammonia gas is turned off and the heating of the solid boric acid is stopped. 100 sccm of hydrogen gas is introduced to maintain a reducing atmosphere in the reaction chamber. When the reaction chamber is cooled to room temperature, the carrier gas is turned off, and the boric acid or boron oxide residue on the surface of the hexagonal boron nitride / graphene / hexagonal boron nitride / SiO2 / Si is washed away by using hot water at 80°C. After being dried, 4 layers of hexagonal boron nitride / single layer of graphene / 4 layers of hexagonal boron nitride stacked heterostructure on a SiO2 / Si substrate is obtained.

[0038] Example 2

[0039] A single-layer hexagonal boron nitride / single-layer graphene / single-layer hexagonal boron nitride stacked heterostructure was prepared. The difference from Example 1 is that high-quality 3-layer graphene was first prepared on a copper-nickel alloy foil by chemical vapor deposition. The copper-nickel alloy foil was surface-treated as described in Example 1, and then placed in a reaction furnace. Under a mixed carrier gas of 300 sccm argon and 200 sccm hydrogen, the temperature was raised to 1050°C in 30 minutes and annealed for 1 hour, and then 1 sccm of methane was introduced for 10 minutes to grow 3-layer graphene on the surface of the metal nickel foil. Then, the 3-layer graphene on the SiO2 / Si substrate was obtained by transfer.

[0040] The preparation process of the single-layer hexagonal boron nitride / single-layer graphene / single-layer hexagonal boron nitride stacked heterostructure is as follows:

[0041] 1) The transferred high-quality 3-layer graphene / SiO2 / Si was placed in a quartz tube (22 mm in diameter), and the high-quality 3-layer graphene / SiO2 / Si was positioned in the central constant temperature zone of the reaction furnace. About 80 mg of solid boric acid was added to the quartz boat upstream of the quartz tube. The reaction chamber was evacuated and then filled with argon to maintain an internal gas pressure of about 20 Torr.

[0042] 2) The reaction furnace was heated to 1000°C in 30 minutes, and the solid boric acid precursor was heated to 300-600°C. At the same time, the argon flow was adjusted to 270 sccm, and 30 sccm of ammonia was introduced. The conversion reaction started with the heating of the solid boric acid and the introduction of gaseous ammonia. After the conversion was completed, the reaction substrate was pushed out of the reaction area by a push-pull rod to achieve rapid cooling, and at the same time the ammonia was turned off and the heating of the solid boric acid was stopped. 100 sccm of hydrogen was introduced to maintain a reducing atmosphere in the reaction chamber. When the reaction chamber was cooled to room temperature, the carrier gas was turned off, and the boric acid or boron oxide residue on the surface of the hexagonal boron nitride / graphene / SiO2 / Si was washed off with 80°C hot water. After drying, a single-layer hexagonal boron nitride / 2-layer graphene / SiO2 / Si was obtained.

[0043] 3) The 2-layer graphene / single-layer hexagonal boron nitride / SiO2 / Si was transferred as described in Example 1.

[0044] 4) The transferred 2-layer graphene / single-layer hexagonal boron nitride / SiO2 / Si was placed in the central constant temperature zone of the quartz tube (22 mm in diameter) of the reaction furnace, and about 80 mg of solid boric acid was added to the quartz boat upstream of the quartz tube. The reaction chamber was evacuated and then filled with argon to maintain an internal gas pressure of about 20 Torr.

[0045] 5) Step 2 was repeated to obtain a single-layer hexagonal boron nitride / single-layer graphene / single-layer hexagonal boron nitride stacked heterostructure.

[0046] Example 3

[0047] A multi-layer hexagonal boron nitride / 2-layer graphene / multi-layer hexagonal boron nitride stack heterostructure was prepared. The difference from Example 1 is that high-quality 10-layer graphene was first prepared on a metal nickel foil by chemical vapor deposition. After the surface-treated metal nickel foil was placed in the reaction furnace, the metal nickel foil was annealed for 1 hour under a mixed carrier gas of 300 sccm argon and 200 sccm hydrogen at 1050°C for 30 minutes, and then 12 sccm of methane was introduced for 5 minutes to grow 10-layer graphene on the surface of the metal nickel foil. Then, the 10-layer graphene on the SiO2 / Si substrate was obtained by transfer. Finally, the upper surface 4 layers and the lower surface 4 layers of the 10-layer graphene were each converted into 4-layer hexagonal boron nitride by the method described in Example 1, thereby preparing a multi-layer hexagonal boron nitride / 2-layer graphene / multi-layer hexagonal boron nitride stack heterostructure.

[0048] Example 4

[0049] A single-layer hexagonal boron nitride / single-layer graphene / single-layer hexagonal boron nitride stack heterostructure was prepared. The difference from Example 2 is that high-quality three-layer graphene on a SiO2 / Si substrate was directly obtained by mechanical exfoliation without the need for CVD growth and transfer steps. Then, the single-layer hexagonal boron nitride / single-layer graphene / single-layer hexagonal boron nitride stack heterostructure was obtained by the conversion reaction steps described in Example 2.

[0050] The results of Example 4 show that the hexagonal boron nitride / graphene / hexagonal boron nitride stack heterojunction material prepared by the method of the present application has high crystalline quality of the intermediate graphene layer, and is not in contact with the outside world, ensuring a clean interface between the hexagonal boron nitride / graphene, laying a foundation for the encapsulation of graphene and greatly improving its electrical, thermal, and chemical properties.

Claims

1. A method for producing a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterostructure material, characterized by, The upper surface and lower surface of the graphene with specified number of layers are converted into hexagonal boron nitride by chemical reaction replacement, thereby forming a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterojunction material; The preparation process of the hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterojunction material is as follows: 1) The first stage: high-quality few-layer or multi-layer graphene is prepared on an initial substrate; for the initial growth substrate that chemically reacts with the precursor for preparing hexagonal boron nitride, the prepared graphene is transferred from the initial growth substrate to an inert substrate; 2) The second stage: the graphene on the initial substrate is placed in a high-temperature chemical reaction chamber, and a precursor for preparing hexagonal boron nitride is introduced to react with the surface layer of the graphene at a high temperature, and the heating temperature is 300-600 ℃; the degree of replacement reaction on the surface of the graphene is controlled by controlling the reaction time, thereby forming a hexagonal boron nitride / graphene vertical heterojunction with a specific number of layers and a stacking order; 3) The third stage: the prepared hexagonal boron nitride / graphene vertical heterojunction is transferred to a secondary substrate, so that the bottom graphene is exposed to the upper side, and then the operation steps of the second stage are repeated to obtain a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterojunction material; the number of layers of the graphene and the hexagonal boron nitride in the stacked heterostructure is controlled by changing the number of layers of the initial graphene and the degree of replacement reaction; In order to facilitate the replacement reaction of the graphene into hexagonal boron nitride, ion beam bombardment, plasma etching or chemical functionalization etching method is used before the second stage to generate defects on the surface layer of the graphene, thereby providing a channel for the subsequent replacement process, so that the replacement reaction of the graphene into hexagonal boron nitride is more likely to occur; In the process of replacing the surface layer of the graphene into hexagonal boron nitride, the graphene containing defects will gradually be converted into hexagonal boron nitride as the replacement reaction time is prolonged, and since the graphene that is not etched has high quality and has an insulating effect on the reactant precursor, the replacement reaction will eventually stop after the graphene containing defects is completely converted into hexagonal boron nitride.

2. The method of producing a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterostructure material according to claim 1, wherein The high-quality graphene used is prepared by exfoliation method, chemical vapor deposition method, silicon carbide pyrolysis method or epitaxy method.

3. The method of producing a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterostructure according to claim 1, wherein The precursor for the chemical reaction replacement is a reactant for preparing hexagonal boron nitride, including ammonia and boric acid, aminoborane, ammonia and sodium tetraborate, ammonia and sodium metaborate, nitrogen and sodium tetraborate.

4. The method of producing a hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterostructure according to claim 1, wherein In the second stage, the precursor for preparing hexagonal boron nitride is directly placed on the surface of the graphene, or is contacted with the graphene by direct evaporation or by being carried by a carrier gas; for the latter two methods, the precursor needs to be heated to 300-600 ℃ to form a high enough concentration.

5. The method of claim 1, wherein the hexagonal boron nitride / graphene / hexagonal boron nitride stacked heterostructure is prepared by the steps of: By controlling the intensity or time of etching, a graphene surface layer with different thicknesses containing defects can be obtained on the original high-quality graphene.

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