Method for preparing two-dimensional molybdenum disulfide film based on reaction adsorption epitaxy

Abstract

The invention belongs to the technical field of wafer-level transition metal sulfide, and relates to a method for preparing a two-dimensional molybdenum disulfide film based on reaction adsorption epitaxy, in particular to a method for preparing large-area, high-crystal-quality and controllable-layer-number two-dimensional molybdenum disulfide. A circulating water cooling system is introduced under a sample table on which a growth substrate is placed, so that the temperature of the surface of the growth substrate can be effectively reduced, adsorption nucleation and epitaxial growth of molybdenum disulfide generated by reaction on the growth substrate are promoted, and large-area preparation of two-dimensional molybdenum disulfide on different substrates is further realized. By controlling the reaction cycle number of the molybdenum precursor source and the sulfur precursor source which are introduced into the reaction chamber, the accurate control of the two-dimensional molybdenum disulfide layer number can be realized. In order to improve the crystallinity of the two-dimensional molybdenum disulfide, infrared heating is adopted to realize rapid temperature rise, the energy required by atom migration in the material is met, and the problems that the material uniformity is difficult to guarantee and the growth substrate is limited when the multi-layer two-dimensional molybdenum disulfide material is prepared by the traditional MOCVD method are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wafer-level transition metal sulfide, and more specifically relates to a method for preparing two-dimensional molybdenum disulfide thin film based on reactive adsorption epitaxy. Background Art

[0002] Field-effect transistors are the cornerstone of the information age. In recent years, as the silicon-based CMOS technology has reached the technical node of 5 nanometers and below, further size reduction has become increasingly difficult. It faces huge challenges for integrated circuits to achieve high integration and high data processing capabilities by directly reducing the channel size. Seeking a technical route for transformative new materials has obvious energy efficiency advantages for continuing Moore's Law.

[0003] Due to the unique atomic layer structure and van der Waals surface without dangling bonds of two-dimensional materials, when the thickness is less than 1 nm, they still maintain a relatively high carrier mobility. Due to the quantum confinement effect, the carriers of two-dimensional materials are confined in the atomic layer plane. When two-dimensional materials are used as the channel of a transistor, they are extremely vulnerable to electrostatic control from the gate, making them immune to the short-channel effect. In addition, the van der Waals heterostructures constructed using two-dimensional materials can break through the limitations of traditional heterojunction epitaxial growth methods and effectively solve the problem of interface charge scattering. Therefore, two-dimensional materials are one of the transformative materials that promote the development of new semiconductor devices and the innovation of integrated circuit technology.

[0004] A new generation of two-dimensional layered semiconductor materials represented by molybdenum disulfide has adjustable band gaps, excellent carrier transport properties, and good chemical stability, and has attracted much attention in the huge two-dimensional material system. In order to achieve the industrial application of two-dimensional molybdenum disulfide, the controllable synthesis of high-quality two-dimensional molybdenum disulfide at the wafer level is crucial.

[0005] The current preparation technologies of two-dimensional molybdenum disulfide are mainly divided into top-down methods and bottom-up methods. Among them, the top-down method gradually thins bulk materials to at least a few layers or even a single layer by means of mechanical exfoliation. However, the size and thickness of the two-dimensional materials obtained by this method are uncontrollable, and it is only suitable for small-scale research in the laboratory; the bottom-up method is a chemical synthesis method represented by chemical vapor deposition for preparing two-dimensional molybdenum disulfide, and it is also the current mainstream method for preparing two-dimensional molybdenum disulfide.

[0006] However, most of the two-dimensional molybdenum disulfide prepared by conventional CVD technology at present are nanosheets with a size ranging from dozens of microns to hundreds of microns, which cannot achieve large-scale integrated manufacturing. Therefore, there is an urgent need to develop a synthesis technology for large-area two-dimensional molybdenum disulfide. Metal-organic chemical vapor deposition (MOCVD) technology is a method for preparing large-size two-dimensional materials using organic gaseous sources. Compared with conventional chemical vapor deposition, it has a precisely controllable growth rate and can achieve large-area and highly reproducible thin film growth. However, when using this method to prepare multi-layer two-dimensional molybdenum disulfide materials, it is difficult to ensure the uniformity of the materials, and the growth cycle will also increase significantly. In addition, the growth substrates of MOCVD are mostly Si / SiO2 and sapphire, which further limits its development. Therefore, there is an urgent need to develop a method for preparing large-area two-dimensional molybdenum disulfide with controllable number of layers on different growth substrates. Summary of the Invention

[0007] The object of the present invention is to provide a method for preparing two-dimensional molybdenum disulfide thin films based on reactive adsorption epitaxy, and more specifically, to provide a method for preparing large-area, high-crystallinity-quality and layer-number-controllable two-dimensional molybdenum disulfide, so as to solve the problems existing in the above-mentioned prior art, realize the preparation of large-area two-dimensional molybdenum disulfide on different substrates, precisely control its number of layers, and at the same time expand the types of substrates used for growing large-area two-dimensional molybdenum disulfide thin films.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] One of the technical solutions of the present invention: Provide a method for preparing large-area, high-crystallinity-quality and layer-number-controllable two-dimensional molybdenum disulfide, the steps include:

[0010] S1. Place the growth substrate with a cooling system below in the reaction chamber, heat and keep the reaction chamber at the deposition temperature; preheat and keep the precursor sources at a certain temperature respectively.

[0011] S2. Under the transportation of the carrier gas, sequentially introduce the precursors into the reaction chamber, and then use the carrier gas to purge to remove the residual reaction raw materials.

[0012] S3. Repeat step S2 at least once to obtain an amorphous molybdenum disulfide thin film.

[0013] S4. After heating the reaction chamber, use the carrier gas purge and the cooling system to cool down.

[0014] S5. Repeat steps S2 to S4 at least once to obtain the two-dimensional molybdenum disulfide.

[0015] Further, the precursor sources are a molybdenum source and a sulfur source.

[0016] Further, the growth substrate includes one of a sapphire substrate, a Si / SiO2 substrate, a Si / HfO2 substrate, a Si / Al2O3 substrate, a Si / ZrO2 substrate, a Si / SrTiO3 substrate, and a mica substrate.

[0017] Further, the deposition temperature is 150 - 300 °C.

[0018] This temperature range is to enable the self-limiting adsorption of the molybdenum source and the sulfur source on the growth substrate, and at the same time provide thermal drive for the reaction of the molybdenum source and the sulfur source.

[0019] Further, the molybdenum source includes at least one of molybdenum hexacarbonyl (Mo(CO)6), molybdenum pentachloride (MoCl5), tris(2,2,6,6-tetramethyl-3,5-heptanedionato)molybdenum (Mo(thd)3), tetrakis(dimethylamino)molybdenum (Mo(NMe2)4), and molybdenum hexafluoride (MoF6).

[0020] Further, the sulfur source includes 10 at least one of diethyl disulfide (C4H6S2), dimethyl sulfide (C2H6S), hydrogen sulfide (H2S), carbon disulfide (CS2), tert-butyl mercaptan (t-BuSH), dimethyl disulfide (C2H6S2), and hexamethyldisilathiane (HMDS).

[0021] Further, the preheating and heat preservation temperature of the molybdenum source is 40 - 200 °C.

[0022] Further, the preheating and heat preservation temperature of the sulfur source is 25 - 150 °C.

[0023] Further, the carrier gas is an inert gas.

[0024] Optionally, the carrier gas is nitrogen, argon, or helium.

[0025] Further, the flow rate of the carrier gas is not less than 30 sccm.

[0026] Optionally, the flow rate of the carrier gas is 30 - 300 sccm.

[0027] Further, the time for introducing the sulfur source is 0.1 - 0.8 s.

[0028] Further, the time for introducing the molybdenum source is 0.05 - 0.5 s.

[0029] Further, for using the carrier gas to purge and remove the residual reactants, after each introduction of the sulfur source or the molybdenum source, the carrier gas is used to purge and remove the residual gaseous reaction raw materials and gaseous reaction products.

[0030] The molybdenum source and sulfur source introduced into the reaction chamber are transported by an inert carrier gas (mainly including high-purity nitrogen, high-purity argon, and high-purity helium). The greater the flow rate of the carrier gas, the more precursor source is introduced into the reaction chamber, and the lower the vacuum degree of the reaction chamber. At the same time, the inert gas is also used to purge the reaction chamber to remove excess gaseous precursors and reaction products in the chamber.

[0031] The longer the time for introducing the molybdenum source and sulfur source into the reaction chamber, the more reaction source is introduced into the reaction chamber. After introducing the sulfur source, wait for 3 - 8 seconds for the precursor source to diffuse evenly in the reaction chamber and adsorb on the surface of the growth substrate, and then perform carrier gas purging. At the same time, after introducing the molybdenum source, also wait for 3 - 8 seconds and then perform carrier gas purging to facilitate the diffusion of the molybdenum precursor source and fully react with the S source adsorbed on the substrate.

[0032] The order of introducing the molybdenum source and sulfur source into the reaction chamber can be reversed. At the same time, the molybdenum source and sulfur source can also be introduced alternately in small amounts and multiple times.

[0033] Further, the number of times of repeating step S2 in step S3 is 5 - 20 times. The more the number of cycles, the thicker the obtained amorphous molybdenum disulfide film.

[0034] Further, the temperature of the heat treatment is 600 - 1000 °C, the heating-up time is less than 1 min, and the heat preservation time is 3 - 6 min.

[0035] This temperature range and time are to provide the energy required for the atomic migration of the amorphous molybdenum disulfide generated by the reaction and improve the crystallization quality of the two-dimensional molybdenum disulfide film.

[0036] Further, the cooling treatment is to reduce the temperature of the reaction chamber to the deposition temperature.

[0037] Among them, the time for the reaction chamber temperature to drop to the deposition temperature is the time for carrier gas purging in the cooling treatment.

[0038] Cool the temperature in the reaction chamber sufficiently to the deposition temperature to prevent the precursor source in the next cycle from undergoing thermal decomposition reaction when entering the reaction chamber at high temperature, which affects the further progress of the subsequent reaction.

[0039] Further, the number of times of repeating steps S2 to S4 in step S5 is 5 - 100 times.

[0040] Control the thickness of the finally prepared two-dimensional molybdenum disulfide by the number of repetitions of step S3 and the number of repetitions of step S5.

[0041] The number of cycles in step S3 and step S5 can be adjusted according to requirements. The more the number of cycles, the thicker the grown two-dimensional molybdenum disulfide film. Too few cycles may result in the inability to form a continuous molybdenum disulfide film. The thickness of the film is proportional to the product of the number of cycles in step S3 and step S5. With the total number of cycles unchanged, appropriately reducing the number of cycles in step S3 and increasing the number of cycles in step S5 can effectively improve the quality and uniformity of the film, but the time consumption will increase accordingly.

[0042] The second technical solution of the present invention: Provide a large-area, high-crystalline-quality and layer-number-controllable two-dimensional molybdenum disulfide, which is prepared by the above preparation method.

[0043] The third technical solution of the present invention: Provide an application of the above large-area, high-crystalline-quality and layer-number-controllable two-dimensional molybdenum disulfide in electronic and optoelectronic devices.

[0044] The fourth technical solution of the present invention: Provide a device for realizing the above preparation method, including: a precursor source system, a carrier gas system, an infrared heating system, a vacuum system, a circulating water cooling system, a reaction chamber and a computer control system;

[0045] The precursor source system and the carrier gas system are connected to the reaction chamber;

[0046] The infrared heating system is used for heating and heat preservation of the precursor source system and the reaction chamber;

[0047] The vacuum system is used to control the gas environment of the reaction chamber;

[0048] The circulating water cooling system is used for temperature control of the growth substrate in the reaction chamber;

[0049] The computer control system is used for real-time control and monitoring of the device;

[0050] The precursor source system includes a sulfur source system and a molybdenum source system.

[0051] The sulfur source system and the molybdenum source system are used to introduce sulfur source and molybdenum source into the reaction chamber, and the carrier gas system is used to introduce carrier gas into the reaction chamber.

[0052] The sample stage for placing the growth substrate is connected to the circulating water cooling system, so that the temperature of the growth substrate on the sample stage is lower than the temperature of the reaction chamber, which is conducive to the low-temperature adsorption and deposition of gaseous precursor sources on the growth substrate. Through the infrared heating system, sufficient energy is provided for the migration of two-dimensional molybdenum disulfide atoms, and the thickness of two-dimensional molybdenum disulfide is accurately controlled by repeating the reaction cycle, realizing the growth of large-area and high-quality two-dimensional molybdenum disulfide on different growth substrates.

[0053] The present invention discloses the following technical effects:

[0054] The present invention can achieve the growth of large-area two-dimensional molybdenum disulfide and precise control of the number of layers by controlling the number of reaction cycles in step S3 and step S4.

[0055] By adopting an infrared heating system, the present invention can rapidly increase the temperature of the substrate surface, provide sufficient energy for the generated molybdenum disulfide material, and further achieve the highly uniform preparation of two-dimensional molybdenum disulfide materials with high crystal quality.

[0056] By introducing a circulating water cooling system under the sample stage where the growth substrate is placed, the present invention can effectively reduce the temperature of the growth substrate surface, making it easier for the generated molybdenum disulfide to adsorb, nucleate, and epitaxially grow on the growth substrate, and further achieve the large-area preparation of two-dimensional molybdenum disulfide on different substrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0058] Figure 1 It is a schematic diagram of the principle for epitaxial preparation of two-dimensional molybdenum disulfide by adsorption reaction.

[0059] Figure 2 They are optical microscope photos and Raman spectra of two-dimensional molybdenum disulfide films prepared in Examples 1-3. Among them, a is the optical microscope photo of Example 1, b is the optical microscope photo of Example 2, c is the optical microscope photo of Example 3, d is the Raman spectrum of Example 1, e is the Raman spectrum of Example 2, and f is the Raman spectrum of Example 3.

[0060] Figure 3 It is a schematic diagram of the device for preparing two-dimensional molybdenum disulfide materials in the present invention.

[0061] Figure 4 They are optical microscope photos comparing the MoS2 films prepared in Examples 4-7 with the growth substrate. Among them, a is Example 5, b is Example 6, c is Example 7, and d is Example 4.

[0062] Figure 5 They are optical microscope photos of the MoS2 films prepared in Comparative Example 1 and Comparative Example 2 and the growth substrate. Among them, a is Comparative Example 1 and b is Comparative Example 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation to the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0064] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0065] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0066] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0067] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0068] The raw materials and reagents used in the specific embodiments of the present invention are all commercially available products.

[0069] Room temperature and normal temperature referred to in the specific embodiments of the present invention both refer to 20 - 30 °C.

[0070] It should be noted that those aspects not detailedly described in the present invention are all conventional operation means in the art and are not the focus of the present invention.

[0071] Figure 3 This is a schematic diagram of the device for preparing two-dimensional molybdenum disulfide material in the present invention.

[0072] Example 1

[0073] The steps for preparing a MoS2 thin film on a Si / SiO2 substrate include:

[0074] S1. Prepare the growth substrate: Take a Si / SiO2 substrate, cut it into wafers with a size of 1.5×1.5 cm, and ultrasonically clean it successively in acetone, isopropyl alcohol, and deionized water to remove organic residues and particulate matter on the substrate surface. After fishing it out from the solution, use a nitrogen gas gun to blow dry the droplet residues on the wafer surface;

[0075] S2. Place the cleaned Si / SiO2 growth substrate on the sample stage of the equipment, close the chamber lid, turn on the circulating water cooling system of the equipment, start the vacuum pump to evacuate the reaction chamber. When the vacuum degree of the reaction chamber reaches below 5×10 -3 Torr, turn on the carrier gas (high-purity nitrogen) to purge the reaction chamber. The carrier gas flow rate is 100 sccm. After introducing the carrier gas, the vacuum degree of the reaction chamber is about 0.215 Torr. After the vacuum degree of the reaction chamber is stabilized, turn on the infrared heating filament to heat and keep the reaction chamber at a constant temperature for 15 min. The heat preservation temperature is 200 °C. At the same time, heat the reaction sources molybdenum hexacarbonyl and diethyl disulfide. The heating temperatures are 65 °C and 40 °C respectively. This heating temperature is to increase the vapor pressure of the two reaction precursor sources in the source bottles, which is convenient for the carrier gas to transport them to the reaction chamber. The heat preservation time is also 15 min;

[0076] S3. Open the source bottles of molybdenum hexacarbonyl and diethyl disulfide. First, introduce molybdenum hexacarbonyl into the reaction chamber for 0.1 s and then wait for 5 s. This process is to enable molybdenum hexacarbonyl to fully diffuse in the reaction chamber and adsorb on the surface of the growth substrate. Then use the carrier gas to purge for 30 s to remove the excess reaction source. Subsequently, introduce diethyl disulfide into the reaction chamber for 0.2 s and wait for 5 s to enable the Mo source adsorbed on the surface of the growth substrate to fully react with the introduced S source. Then use the carrier gas to purge for 30 s to remove the residual reaction products in the chamber. The obtained molybdenum disulfide small lamellae can adsorb and nucleate on the growth substrate at a lower temperature;

[0077] S4. Repeat the operation in step 3 for 8 cycles to enable the molybdenum disulfide adsorbed on the growth substrate to nucleate and grow uniformly and cover the entire growth substrate;

[0078] S5. Turn on the infrared heating system to quickly raise the temperature of the reaction chamber to 800 °C and keep it at a constant temperature for 4 min to provide sufficient energy for the atomic migration of the two-dimensional molybdenum disulfide material, enabling it to fully epitaxially grow and improving the crystallinity of the thin film material;

[0079] S6. Turn off the infrared heating system and use nitrogen to purge fully for 15 min. Under the action of nitrogen and the circulating water cooling system, quickly cool the substrate temperature to the deposition temperature (200 °C);

[0080] S7. Repeat the operations from step S3 to step S6 for 10 times to obtain a high-quality uniform two-dimensional molybdenum disulfide thin film.

[0081] Example 2

[0082] Compared with Example 1, the only difference is that the number of repetitions in step S7 is 20 times.

[0083] Example 3

[0084] Compared with Example 1, the only difference is that the number of repetitions in step S7 is 30 times.

[0085] Example 4

[0086] Compared with Example 1, the only difference is that the growth substrate is a sapphire substrate.

[0087] Example 5

[0088] Compared with Example 1, the only difference is that the growth substrate is a Si / HfO2 substrate.

[0089] Example 6

[0090] Compared with Example 1, the only difference is that the growth substrate is a Si / Al2O3 substrate.

[0091] Example 7

[0092] Compared with Example 1, the only difference is that the growth substrate is a Si / ZrO2 substrate.

[0093] Comparative Example 1

[0094] Compared with Example 1, the only difference is that in step S6, only nitrogen purging is used to cool the substrate.

[0095] Comparative Example 2

[0096] Compared with Example 1, the only difference is that step S6 is reduced, that is, after turning off the infrared heating system, no cooling is carried out, and steps S3 to S5 are directly repeated.

[0097] Test Example

[0098] Figure 1 Schematic diagram of the principle for preparing two-dimensional molybdenum disulfide by adsorption reaction epitaxy.

[0099] Figure 2 Optical microscope photos and Raman spectra of the two-dimensional molybdenum disulfide films prepared in Examples 1-3. Among them, a is the optical microscope photo of Example 1, b is the optical microscope photo of Example 2, c is the optical microscope photo of Example 3, d is the Raman spectrum of Example 1, e is the Raman spectrum of Example 2, and f is the Raman spectrum of Example 3. From Figure 2It can be seen that a two-dimensional MoS2 film with uniform thickness was successfully prepared on the Si / SiO2 substrate. A scratch was artificially introduced in each of Figures a and b to compare the color contrast change between the grown MoS2 and the substrate under an optical microscope. The results of Raman spectroscopy characterization all showed sharp characteristic Raman peaks of MoS2. The full width at half maximum of the A peak in Figure d was only 7.6 cm 1g which is comparable to that of MoS2 prepared by traditional chemical vapor deposition, indicating that the prepared material has excellent crystal quality. The peak position difference between the two characteristic peaks can be used to characterize the number of layers of MoS2. Among them, the peak position difference between E -1 and A 1 2g in Figures d to e was 22 cm 1g 24 cm -1 and 25.3 cm -1 respectively, corresponding to 2 layers, 5 layers and more than 8 layers of MoS2. The control of the thickness of MoS2 was successfully achieved. -1

[0100] Figure 4 Figures 16 to 19 are optical microscope photos of the MoS2 films prepared in Examples 4-7 compared with the growth substrates. Among them, a is Example 5, b is Example 6, c is Example 7, and d is Example 4. Through the optical microscope photos of the two-dimensional MoS2 films prepared on different growth substrates compared with the growth substrates, it can be found that the uniform deposition of MoS2 on different substrates was achieved by using the method of the present invention.

[0101] Figure 5 Figures 20 to 23 are optical microscope photos of the MoS2 films prepared in Comparative Example 1 and Comparative Example 2 compared with the growth substrates. Among them, a is Comparative Example 1 and b is Comparative Example 2. It can be seen from the figures that Comparative Examples 1 and 2 are optical microscope photos of the comparison with the growth substrate after the process is completed. It can be seen that the growth of MoS2 was not achieved because the cooling rate was too slow, and the reaction source in the next cycle decomposed thermally when it entered the chamber at too high a temperature, resulting in the inability to carry out the adsorption reaction.

[0102] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0103] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.​

Claims

1. A method for preparing two-dimensional molybdenum disulfide with a large area, high crystal quality and controllable number of layers, characterized in that the steps Including: S1. Place a growth substrate with a cooling system below in a reaction chamber, heat and keep the reaction chamber at a deposition temperature; preheat and keep the precursor sources at a certain temperature respectively. S2. Under the transportation of a carrier gas, introduce precursors into the reaction chamber in sequence, and then use the carrier gas to purge and remove residual reactants. S3. Repeat step S2 at least once to obtain an amorphous molybdenum disulfide film. S4. After heating the reaction chamber, use the carrier gas purge and the cooling system to cool down. S5. Repeat steps S2 to S4 at least once to obtain the two-dimensional molybdenum disulfide. The precursor sources are a molybdenum source and a sulfur source.

2. The preparation method according to claim 1, wherein, In step S1: The deposition temperature is 150 - 300 °C; and / or, the molybdenum source includes at least one of molybdenum hexacarbonyl, molybdenum pentachloride, tris(2,2,6,6-tetramethyl-3,5-heptanedionato)molybdenum, tetrakis(dimethylamino)molybdenum, and molybdenum hexafluoride; and / or, the sulfur source includes at least one of diethyl disulfide, dimethyl sulfide, hydrogen sulfide, carbon disulfide, tert-butyl mercaptan, dimethyl disulfide, and hexamethyldisilathiane.

3. The preparation method according to claim 1, characterized in that, In step S2: The time for introducing the sulfur source is 0.1 - 0.8 s; and / or, the time for introducing the molybdenum source is 0.05 - 0.5 s; using the carrier gas to purge and remove residual reactants means that after introducing the sulfur source or the molybdenum source each time, use the carrier gas to purge and remove residual gaseous reaction raw materials and gaseous reaction products.

4. The preparation method according to claim 1, characterized in that, The carrier gas is an inert gas; and / or, the flow rate of the carrier gas is not less than 30 sccm.

5. The preparation method according to claim 1, characterized in that, The temperature of the heating treatment is 600 - 1000 °C, the heating-up time is less than 1 min, and the heat preservation time is 3 - 6 min.

6. The preparation method according to claim 1, characterized in that, The cooling treatment is to reduce the temperature of the reaction chamber to the deposition temperature.

7. The preparation method according to claim 1, characterized in that The number of times of repeating step S2 in step S3 is 5 - 20 times; and / or, the number of times of repeating steps S2 to S4 in step S5 is 5 - 100 times.

8. A two-dimensional molybdenum disulfide with a large area, high crystal quality and controllable number of layers, characterized in that, The two-dimensional molybdenum disulfide is prepared by the preparation method according to any one of claims 1 - 7.

9. Application of the two-dimensional molybdenum disulfide with large area, high crystal quality and controllable number of layers according to claim 8 in electronic and optoelectronic devices.

10. An apparatus for implementing the preparation method according to any one of claims 1-7, characterized in that, Including: A precursor source system, a carrier gas system, an infrared heating system, a vacuum system, a circulating water cooling system, a reaction chamber, and a computer control system; The precursor source system and the carrier gas system are connected to the reaction chamber; The infrared heating system is used for heating and keeping the precursor source system and the reaction chamber at a certain temperature; The vacuum system is used to control the gas environment of the reaction chamber; The circulating water cooling system is used for controlling the temperature of the growth substrate in the reaction chamber; The computer control system is used for real-time control and monitoring of the device; The precursor source system includes a sulfur source system and a molybdenum source system.

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