Wafer-level monolayer molybdenum disulfide film and preparation method thereof

Abstract

The application discloses a wafer-level single-layer MoS2 film and a preparation method thereof, and the method comprises the following steps: placing sulfur powder and molybdenum trioxide powder as reaction precursors into two quartz boats respectively, and placing the quartz boat containing the sulfur powder, the quartz boat containing the molybdenum trioxide powder and a C-surface sapphire substrate vertically placed in the direction of the air flow into a first temperature zone, a second temperature zone and a third temperature zone of a single-tube CVD tube furnace respectively; introducing a carrier gas into the single-tube CVD tube furnace after cleaning, and heating the sulfur powder, the molybdenum trioxide powder and the C-surface sapphire substrate when the preset furnace pressure is reached, so that a wafer-level single-layer MoS2 film with good uniformity and high quality is formed, and the technical problems of low yield and poor uniformity of the two-dimensional MoS2 film obtained by mechanical peeling are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of wafer-level two-dimensional semiconductor thin film preparation, and in particular relates to a wafer-level single-layer MoS2 thin film and a preparation method thereof. Background Art

[0002] For over half a century, integrated circuits have continued to develop according to the trends predicted by Moore's Law, now reaching the 5nm technology node. However, further scaling of transistors faces limitations in physics, power consumption, and process costs. This is fundamentally due to the scaling bottlenecks faced by traditional three-dimensional materials. For example, when silicon is thinned to a single layer or a few layers, its surface atoms form bonds with other impurity atoms, causing the semiconductor properties to be lost in certain areas. In recent years, two-dimensional van der Waals materials have attracted widespread attention due to their atomically thin thickness, excellent optoelectronic properties, and good thermal stability, becoming a key candidate for continuing Moore's Law.

[0003] Among two-dimensional van der Waals materials, transition metal dichalcogenides (TMDCs) are gaining increasing attention. This diverse family of materials encompasses semiconductors like WSe2 and WS2, as well as metallic materials like TaS2 and NiS2. TMDCs not only possess high carrier mobility, chemical stability, and electrostatic controllability, but also possess tunable band gaps, transitioning from indirect to direct band gaps as the number of material layers decreases. These physicochemical properties have laid the foundation for their applications in rectifier diodes, photodetectors, memory devices, humidity sensors, and supercapacitors.

[0004] MoS2 is the most widely studied semiconductor material among transition metal chalcogenides. It has a hexagonal lattice structure, with sulfur atoms and molybdenum atoms within the plane connected by covalent bonds, and layers outside the plane connected by van der Waals forces. The number of MoS2 layers significantly affects its physical and chemical properties. As the number of layers decreases from multiple layers to at least one layer or even a single layer, the optical band gap of MoS2 gradually increases and transforms from an indirect band gap to a direct band gap. The thickness of a single layer of MoS2 is only 0.6nm, with a band gap of approximately 1.9eV, and excellent optoelectronic properties. This gives it strong photoluminescence properties, promoting its research and application in the field of optoelectronic properties. At the same time, single-layer MoS2 has a higher carrier mobility, which makes its application in sensors, logic memory devices, high-efficiency field-effect transistors (FETs) and other fields more extensive.

[0005] Currently, the preparation method of two-dimensional MoS2 thin films is top-down, that is, a few layers of MoS2 thin films are prepared by mechanical exfoliation. However, the exfoliation process is relatively cumbersome, requiring a lot of time and human resources, and has poor repeatability. The thickness of the two-dimensional material obtained by exfoliation is random, so it is not suitable for the preparation of large-area two-dimensional materials. Summary of the Invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a wafer-level single-layer MoS2 film and a preparation method thereof. By adopting a simple single-tube three-temperature zone CVD tube furnace equipment, using a mixture of argon and hydrogen as a carrier gas, a reducing atmosphere is provided for sulfur powder and molybdenum trioxide powder, and depositing a wafer-level single-layer MoS2 film with good uniformity and high quality on a vertically placed C-sapphire, the technical problems of low yield and poor uniformity of the two-dimensional MoS2 film obtained by existing mechanical peeling are solved. The preparation method of the present invention is conducive to the large-scale production and application of wafer-level single-layer MoS2 films with good uniformity and high quality.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a wafer-level single-layer MoS2 thin film comprises the following steps:

[0009] Sulfur powder and molybdenum trioxide powder were placed as reaction precursors in two quartz boats respectively, and the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder and a C-plane sapphire substrate placed vertically facing the airflow direction were placed in the first temperature zone, the second temperature zone and the third temperature zone of a single-tube CVD tube furnace respectively;

[0010] The carrier gas is introduced into the cleaned single-tube CVD tube furnace. When the pressure in the furnace reaches normal pressure, the sulfur powder, molybdenum trioxide powder and C-face sapphire substrate are heated separately to form a wafer-level MoS2 film with a precise single-layer thickness.

[0011] The mass ratio of the sulfur powder to the molybdenum trioxide powder is (800-1000):1.

[0012] The quartz boat filled with sulfur powder, the quartz boat filled with molybdenum trioxide powder and the C-surface sapphire substrate placed vertically facing the airflow direction are respectively placed at the middle thermocouples of the corresponding temperature zones.

[0013] The cleaning operation of the single-tube CVD tube furnace is as follows:

[0014] Seal the single-tube CVD tube furnace and evacuate the quartz tube. When the vacuum degree is below 10 Pa, turn off the vacuum pump, open the gas valve, and introduce 500-600 sccm of argon until the pressure inside the quartz tube returns to normal pressure. Repeat the above operation at least three times.

[0015] The carrier gas is composed of 95% argon and 5% hydrogen, and the flow rate of the carrier gas is 80-100 sccm.

[0016] The heating conditions of the single-tube CVD tube furnace are:

[0017] The first temperature zone is raised to 150-200 DEG C at a temperature raising rate of 3.5-5 DEG C / min; the second temperature zone is raised to 580-650 DEG C at a temperature raising rate of 14.5-16 DEG C / min; the third temperature zone is raised to 950-965 DEG C at a temperature raising rate of 23.5-25 DEG C / min; after the three temperature zones reach the set temperature, the temperature is kept for 1 h, i.e. the growth time is 1 h, and after the temperature keeping ends, the temperature is naturally cooled to room temperature.

[0018] The application further provides a wafer-level single-layer MoS2 film prepared by the preparation method.

[0019] The wafer-level single-layer MoS2 film has a chemical formula of MoS2, a thickness of 0.6 nm, wafer-level and triangular domain structures, and a triangular domain size of a hundred microns.

[0020] Compared with the prior art, the application has the beneficial effects that:

[0021] 1. The application vertically places the C-surface sapphire substrate at the middle thermocouple position of the third temperature zone of the single-tube CVD tube furnace, so that the temperature of the substrate can be accurately controlled, and the concentration of the precursor raw material is relatively uniform at the cross section of the substrate position, and the MoS2 film obtained by growth has good uniformity.

[0022] 2. The application adopts the single-tube CVD tube furnace, and the gas supply system is a single gas passage, so that the equipment is simpler than the multi-tube CVD tube furnace, and the operation is more convenient, and the wafer-level MoS2 film obtained by growth has good uniformity and high quality.

[0023] 3. The application introduces the mixed gas of 95% argon and 5% hydrogen when growing the MoS2 film, and the hydrogen as a reducing atmosphere makes the molybdenum element and sulfur in the molybdenum trioxide more easily reduced, and the two are more easily reacted to obtain MoS2, so that the MoS2 film with good uniformity is deposited on the sapphire substrate.

[0024] 4. The application performs three times of pumping and replenishing, i.e. three times of repeated pumping and replenishing, on the single-tube CVD tube furnace, so that the growth environment of MoS2 has high cleanliness, and it is more conducive to growing the MoS2 film with high quality and uniform composition.

[0025] In summary, the application prepares the wafer-level single-layer MoS2 film based on the chemical vapor deposition method, and the film has high quality and uniform composition, the triangular domain size is a hundred microns, and is suitable for the current mainstream micro-nano processing technology, and provides a basis for the preparation and integration of micro-nano electronic devices. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1Schematic diagram of a single-tube CVD tube furnace and a vertically placed substrate.

[0027] Figure 2 Schematic diagram of the substrate being placed vertically.

[0028] Figure 3 The following are photos of wafer-level single-layer MoS2 films prepared under different carrier gas components of the present invention, wherein: Figure 3 (a) is argon and oxygen, Figure 3 (b) is argon, Figure 3 (c) Argon and hydrogen.

[0029] Figure 4 This is an optical microscope image of a wafer-level single-layer MoS2 film prepared in Example 3 of the present invention, wherein: Figure 4 (a) is at low magnification, and 4(b) is at high magnification.

[0030] Figure 5 This is a microscope image of a wafer-level single-layer MoS2 film prepared in Example 3 of the present invention, wherein: Figure 5 (a) is an optical microscope image, 5(b) is Figure 5 Atomic force microscopy image of the enlarged part in (a).

[0031] Figure 6 This is the Raman shift spectrum of the wafer-level single-layer MoS2 film prepared in Example 3 of the present invention.

[0032] Figure 7 This is the second harmonic generation spectrum of the wafer-level single-layer MoS2 thin film prepared in Example 3 of the present invention.

[0033] Figure 8 This is a linear fitting diagram of the second harmonic and laser intensity of the wafer-level single-layer MoS2 film prepared in Example 3 of the present invention.

[0034] Figure 9 This is the polarization diagram of the second harmonic of the wafer-level single-layer MoS2 thin film prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0036] A wafer-level single-layer MoS2 film has a chemical formula of MoS2. The thickness of the wafer-level transition metal chalcogenide film is 0.6 nm, i.e., the single-layer MoS2 film has a wafer-level and microscopic triangular domain structure, and the triangular domain size is on the order of hundreds of microns.

[0037] like Figure 1 and Figure 2As shown, a method for preparing a wafer-level single-layer MoS2 thin film includes the following steps:

[0038] Step 1: Sulfur powder and molybdenum trioxide powder are placed as reaction precursors in two quartz boats respectively, and the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder, and a 2-inch C-plane sapphire substrate placed vertically facing the airflow direction are placed in the positions corresponding to the thermocouples in the middle of the first temperature zone, the second temperature zone, and the third temperature zone in a single-tube CVD tube furnace, respectively, to facilitate precise control of the temperature of the sulfur powder, molybdenum trioxide powder, and sapphire, with a distance of about 50 cm between each. The mass ratio of the sulfur powder to the molybdenum trioxide powder is (800-1000):1. The sapphire substrate placed vertically facing the airflow direction enables the reaction precursors to mix and react more evenly near the substrate, thereby improving the uniformity of the reaction precursor deposition. The quartz tube of the single-tube CVD tube furnace has a diameter of 8 cm and a length of 180 cm.

[0039] Step 2: Clean the single-tube CVD tube furnace: Seal the single-tube CVD tube furnace and evacuate the quartz tube to remove impurity gases inside the quartz tube. When the vacuum degree is below 10 Pa, turn off the vacuum pump, open the gas valve, and slowly introduce 500-600 sccm of argon until the pressure inside the quartz tube returns to normal pressure. Repeat the above operation at least three times to ensure the cleanliness of the reaction environment.

[0040] Step 3: After the single-tube CVD tube furnace is cleaned, the carrier gas is introduced into the single-tube CVD tube furnace. When the pressure in the furnace reaches normal pressure, that is, 1×10 5 Pa, the sulfur powder, molybdenum trioxide powder and C-face sapphire substrate are heated separately. After reaching the set temperature, the precursor is transported to the vicinity of the surface of the C-face sapphire substrate under the action of a carrier gas. The reactants are adsorbed on the substrate surface and chemically react to form a single-layer wafer-level MoS2 film; the carrier gas is composed of 95% argon and 5% hydrogen by volume, and the flow rate of the carrier gas is 80-100sccm. By introducing a small amount of hydrogen as a carrier gas, a reducing atmosphere is provided, which is more conducive to the chemical reaction between the molybdenum trioxide powder and sulfur, thereby depositing a MoS2 film on the sapphire substrate;

[0041] The heating conditions of the single-tube CVD tube furnace are as follows: the first temperature zone is heated to 150-200° C. at a heating rate of 3.5-5° C. / min; the second temperature zone is heated to 580-650° C. at a heating rate of 14.5-16° C. / min; the third temperature zone is heated to 950-965° C. at a heating rate of 23.5-25° C. / min; after the three temperature zones reach the set temperature, they are kept warm for 1 hour, that is, the growth time is 1 hour. After the heat preservation is completed, they are naturally cooled to room temperature.

[0042] Example 1

[0043] A method for preparing a wafer-level single-layer MoS2 thin film comprises the following steps:

[0044] Step 1: Weigh 8g of sulfur powder and 10mg of molybdenum trioxide powder as reaction precursors and place them in two quartz boats respectively. Then, place the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder, and a C-plane sapphire substrate placed vertically in the direction of airflow into the thermocouples of the first temperature zone, the second temperature zone, and the third temperature zone in a single-tube CVD tube furnace respectively.

[0045] Step 2: Clean the single-tube CVD tube furnace: Seal the single-tube CVD tube furnace and evacuate the quartz tube to remove impurity gases inside the quartz tube. When the vacuum degree is below 10 Pa, turn off the vacuum pump, open the gas valve, and slowly introduce 500 sccm of argon until the pressure inside the quartz tube returns to normal pressure. Repeat the above steps three times to ensure the cleanliness of the reaction environment.

[0046] Step 3: After the single-tube CVD tube furnace is cleaned, 80 sccm of carrier gas is introduced into the single-tube CVD tube furnace, where the carrier gas is composed of 95% argon and 5% hydrogen by volume. When the pressure in the furnace reaches normal pressure, the sulfur powder, molybdenum trioxide powder and C-face sapphire substrate are heated respectively. The first temperature zone is heated to 150°C at a heating rate of 3.5°C / min; the second temperature zone is heated to 580°C at a heating rate of 14.5°C / min; the third temperature zone is heated to 950°C at a heating rate of 23.5°C / min. The three temperature zones reach the set temperature at 40 minutes respectively, and are kept warm for 1 hour. After the insulation is completed, they are naturally cooled to room temperature.

[0047] Example 2

[0048] A method for preparing a wafer-level single-layer MoS2 thin film comprises the following steps:

[0049] Step 1: Weigh 9g of sulfur powder and 10mg of molybdenum trioxide powder as reaction precursors and place them in two quartz boats respectively. Then, place the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder, and a C-plane sapphire substrate placed vertically in the direction of airflow into the thermocouples of the first, second, and third temperature zones of a single-tube CVD tube furnace respectively.

[0050] Step 2: Clean the single-tube CVD tube furnace: Seal the single-tube CVD tube furnace and evacuate the quartz tube to remove impurity gases inside the quartz tube. When the vacuum degree is below 10 Pa, turn off the vacuum pump, open the gas valve, and slowly introduce 550 sccm of argon until the pressure inside the quartz tube returns to normal pressure. Repeat the above steps three times to ensure the cleanliness of the reaction environment.

[0051] Step 3: After the single-tube CVD tube furnace is cleaned, 90 sccm of carrier gas is introduced into the single-tube CVD tube furnace, where the carrier gas is composed of 95% argon and 5% hydrogen by volume. When the pressure in the furnace reaches normal pressure, the sulfur powder, molybdenum trioxide powder and C-face sapphire substrate are heated respectively. The first temperature zone is heated to 180°C at a heating rate of 4.5°C / min; the second temperature zone is heated to 600°C at a heating rate of 15°C / min; the third temperature zone is heated to 960°C at a heating rate of 24°C / min. The three temperature zones reach the set temperature at 40 minutes respectively, and are kept warm for 1 hour. After the insulation is completed, they are naturally cooled to room temperature.

[0052] Example 3

[0053] A method for preparing a wafer-level single-layer MoS2 thin film comprises the following steps:

[0054] Step 1: Weigh 10g of sulfur powder and 10mg of molybdenum trioxide powder as reaction precursors and place them in two quartz boats respectively. Then, place the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder, and a C-plane sapphire substrate placed vertically in the direction of airflow into the thermocouples of the first temperature zone, the second temperature zone, and the third temperature zone in a single-tube CVD tube furnace respectively.

[0055] Step 2: Clean the single-tube CVD tube furnace: Seal the single-tube CVD tube furnace and evacuate the quartz tube to remove impurity gases inside the quartz tube. When the vacuum degree is below 10 Pa, turn off the vacuum pump, open the gas valve, and slowly introduce 600 sccm of argon until the pressure inside the quartz tube returns to normal pressure. Repeat the above steps three times to ensure the cleanliness of the reaction environment.

[0056] Step 3: After the single-tube CVD tube furnace is cleaned, 100 sccm of carrier gas is introduced into the single-tube CVD tube furnace, where the carrier gas is composed of 95% argon and 5% hydrogen by volume. When the pressure in the furnace reaches normal pressure, the sulfur powder, molybdenum trioxide powder and C-face sapphire substrate are heated respectively. The first temperature zone is heated to 200°C at a heating rate of 5°C / min; the second temperature zone is heated to 650°C at a heating rate of 16°C / min; and the third temperature zone is heated to 965°C at a heating rate of 25°C / min. The three temperature zones reach the set temperature at 40 minutes respectively, and are kept warm for 1 hour. After the insulation is completed, they are naturally cooled to room temperature.

[0057] Comparative Example 1

[0058] The process and parameters of this comparative example are the same as those of Example 3, except that in step 3, the carrier gas introduced into the single-tube CVD tube furnace is 96 sccm of argon and 4 sccm of oxygen. The film prepared is as follows: Figure 3As shown in (a), it can be seen that the C-plane sapphire substrate after growth is different from the pure C-plane sapphire substrate ( Figure 2 ), and no obvious contrast change was found, indicating that when growing wafer-level MoS2 in a single-tube CVD tube furnace, the introduction of oxygen will provide an oxidizing environment, which is not conducive to the chemical reaction of molybdenum trioxide and sulfur powder. At the same time, oxygen will etch the grown MoS2 triangular domains, which is not conducive to the growth of wafer-level MoS2 in a single tube.

[0059] Comparative Example 2

[0060] The process and parameters of this comparative example are the same as those of Example 3, except that in step 3, the carrier gas introduced into the single-tube CVD tube furnace is argon, and the film prepared is as follows: Figure 3 As shown in (b), it can be seen that the uniformity of the grown wafer-level MoS2 is poor, with a deeper contrast at the edge of the C-plane sapphire and a shallower contrast in the middle, indicating the uneven nucleation density, that is, molybdenum trioxide and sulfur are more likely to react to form MoS2 at the edge of the substrate.

[0061] Figure 3 (c) is a photograph of a wafer-level monolayer MoS2 film prepared in Example 3 of the present invention. It can be seen that the grown wafer-level MoS2 exhibits good uniformity, with the overall contrast of the C-plane sapphire being uniform, indicating that the nucleation density of the contrast is also relatively uniform. Since the introduction of hydrogen provides a reducing atmosphere, the reaction of molybdenum trioxide and sulfur to produce MoS2 requires a reduction in the valence of both molybdenum and sulfur, and hydrogen provides the reducing properties that facilitate the reaction between molybdenum trioxide and sulfur, thereby making the nucleation density on the substrate uniform. Furthermore, the continuous and stable supply of precursor materials allows the growth of MoS2 triangular domains.

[0062] Figure 4 This is an optical microscope image of a wafer-level single-layer MoS2 film prepared in Example 3 of the present invention. Figure 4 (a) is low resolution, Figure 4 (b) high resolution, Figure 4 (b) Yes Figure 4 The enlarged image of the red box in (a) is made by Figure 4 (a) It can be seen that the grown MoS2 exhibits a clear triangular domain structure with a large nucleation density and a relatively consistent orientation. Figure 4 (b) It can be seen that the average size of the MoS2 triangular domain is about 100 microns, which is suitable for the current mainstream micro-nano processing technology and provides a basis for the preparation of micro-nano electronic devices.

[0063] Figure 5 (a) is an optical microscope image of a wafer-level MoS2 thin film prepared in Example 3 of the present invention, Figure 5 (b) Figure 5The atomic force microscope image of the black box in (a) is Figure 5 (b) It can be seen that the thickness of the wafer-level MoS2 triangular domain prepared by the present invention is 0.6nm. Figure 5 From the contrast of the triangular domains in (a), it can be found that the thickness of the triangular domain structure is almost uniform, indicating that the wafer-level MoS2 prepared by the present invention has high uniformity.

[0064] Figure 6 The Raman shift spectrum of the wafer-level MoS2 film prepared in Example 3 of the present invention shows that -1 and 407.41cm -1 There are two obvious peaks at 1 2g and A 1g Two characteristic Raman vibration modes, among which E 1 2g represents the in-plane vibration of molybdenum atoms and sulfur atoms, A 1g represents the out-of-plane vibration of sulfur atoms, and the difference between the two peaks (A 1g -E 1 2g ) is 20.66cm -1 (Lee C, Yan H, Brus LE, et al. Anomalous Lattice Vibrations of Single- and Few-Layer MoS2[J]. ACS Nano, 2010, 4: 2695-2700). This result is similar to that reported previously, indicating that the wafer-level MoS2 prepared by the present invention is of high quality and uniform composition.

[0065] Figure 7 The second harmonic generation spectrum of the wafer-level MoS2 thin film prepared in Example 3 of the present invention is as follows. The incident laser wavelength is 1550nm pump light, and the peak value of 775nm can be clearly detected. In addition, the signal intensity of the second harmonic received by the incident laser of different powers is adjustable. It can be seen that the wafer-level MoS2 prepared by the present invention is a non-centrosymmetric structure with high crystal quality. The wafer-level MoS2 prepared by the present invention provides a basis for applications in the field of nonlinear optics.

[0066] Figure 8 This is a relationship diagram between the second harmonic intensity of the wafer-level MoS2 thin film prepared in Example 3 of the present invention and the incident pump light intensity in logarithmic coordinates. The fitting coefficient is as high as 2.069, indicating that the second harmonic intensity of the wafer-level MoS2 thin film prepared in the present invention has a strong quadratic relationship with the incident pump light intensity.

[0067] Figure 9This is a polarization-resolved second harmonic intensity measurement graph of the wafer-level single-layer MoS2 film prepared in Example 3 of the present invention. It can be seen that the spectrum presents an obvious six-petal shape, that is, its characteristic sextuple mode, indicating that the wafer-level MoS2 film prepared by the present invention has good crystallinity and has a three-fold rotational crystal symmetry.

Claims

1. A method for preparing a wafer-level single-layer MoS2 thin film, characterized in that: The following steps are involved: Sulfur powder and molybdenum trioxide powder are placed as reaction precursors in two quartz boats, respectively. The quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder, and a C-surface sapphire substrate placed vertically facing the airflow direction are respectively placed in the first temperature zone, the second temperature zone, and the third temperature zone of a single-tube CVD tube furnace; the mass ratio of the sulfur powder to the molybdenum trioxide powder is (800-1000):1; A carrier gas is introduced into the cleaned single-tube CVD tube furnace. When the pressure in the furnace reaches atmospheric pressure, the sulfur powder, molybdenum trioxide powder, and C-plane sapphire substrate are heated separately to form a wafer-level single-layer MoS2 thin film. The carrier gas is composed of 95% argon and 5% hydrogen by volume, and the flow rate of the carrier gas is 80-100 sccm. The heating conditions of the single-tube CVD tube furnace are as follows: The first temperature zone is heated to 150-200°C at a heating rate of 3.5-5°C / min; the second temperature zone is heated to 580-650°C at a heating rate of 14.5-16°C / min; the third temperature zone is heated to 950-965°C at a heating rate of 23.5-25°C / min; after the three temperature zones reach the set temperature, they are kept warm for 1 hour, that is, the growth time is 1 hour. After the insulation is completed, they are naturally cooled to room temperature.

2. The method for preparing a wafer-level single-layer MoS2 thin film according to claim 1, wherein: The quartz boat filled with sulfur powder, the quartz boat filled with molybdenum trioxide powder and the C-surface sapphire substrate placed vertically facing the airflow direction are respectively placed at the middle thermocouples of the corresponding temperature zones.

3. The method for preparing a wafer-level single-layer MoS2 thin film according to claim 1, wherein: The cleaning operation of the single-tube CVD tube furnace is as follows: Seal the single-tube CVD tube furnace and evacuate the quartz tube. When the vacuum degree is below 10 Pa, turn off the vacuum pump, open the gas valve, and introduce 500-600 sccm of argon until the pressure inside the quartz tube returns to normal pressure. Repeat the above operation at least three times.

4. A wafer-level single-layer MoS2 thin film prepared by the method for preparing a wafer-level single-layer MoS2 thin film according to any one of claims 1 to 3.

5. The wafer-level single-layer MoS2 thin film according to claim 4, characterized in that: The wafer-level single-layer MoS2 film has a chemical formula of MoS2, a thickness of 0.6 nm, and has a wafer-level and triangular domain structure, with a triangular domain size of hundreds of microns.

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