Wafer-level single-layer MoS2 film and preparation method thereof

Abstract

The invention discloses a wafer-level single-layer MoS2 film and a preparation method thereof, and the method comprises the steps: taking sulfur powder and molybdenum trioxide powder as reaction precursors, and respectively placing the reaction precursors in two quartz boats; the quartz boat containing the sulfur powder, the quartz boat containing the molybdenum trioxide powder and the C-face sapphire substrate which is vertically placed in the air flow circulation direction are placed in a first temperature zone, a second temperature zone and a third temperature zone in the single-tube type CVD tube furnace respectively, wherein the first temperature zone, the second temperature zone and the third temperature zone are arranged in the single-tube type CVD tube furnace; the method comprises the following steps: cleaning a single-tube CVD tube furnace, introducing a carrier gas into the cleaned single-tube CVD tube furnace, respectively heating sulfur powder, molybdenum trioxide powder and a C-plane sapphire substrate when a preset pressure in the furnace is reached, and forming a wafer-level single-layer MoS2 film with good uniformity and relatively high quality, thereby solving the technical problems of low yield and poor uniformity of a two-dimensional MoS2 film obtained by existing mechanical stripping.

Description

Technical Field

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

[0002] Over the past half century, integrated circuits have been developing in accordance with the trend predicted by Moore's Law, and have now reached the 5nm technology node. Further miniaturization of transistors will face limitations in physical principles, power consumption, process costs, etc. This is essentially due to the bottleneck of traditional three-dimensional materials in size miniaturization. For example, when silicon materials are thinned to a single layer or a few layers, their surface atoms will form bonds with other impurity atoms, thereby locally losing their semiconductor properties. In recent years, two-dimensional van der Waals materials have attracted widespread attention due to their atomic-level thickness, excellent optoelectronic properties, and good thermal stability, becoming one of the important candidate materials for the continuation of Moore's Law.

[0003] Among two-dimensional van der Waals materials, transition metal dichalcogenides (TMDCs) have gradually attracted people's attention. This material family is diverse, including WSe2 and WS2 with semiconductor properties, as well as TaS2 and NiS2 with metallic properties. TMDCs not only have high carrier mobility, chemical stability, and electrostatic controllability, but also have adjustable band gaps, which can be transformed from indirect band gaps to direct band gaps as the number of material layers decreases. These physical and chemical properties have laid the foundation for their applications in rectifier diodes, photodetectors, storage devices, humidity sensors, and supercapacitors.

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

[0005] Currently, the preparation method of two-dimensional MoS2 film is top-down, that is, a few layers of MoS2 film are prepared by mechanical exfoliation. However, the exfoliation process is cumbersome, requires 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, a mixture of argon and hydrogen is used as a carrier gas to provide a reducing atmosphere for sulfur powder and molybdenum trioxide powder, and a wafer-level single-layer MoS2 film with good uniformity and high quality is deposited on a vertically placed C-sapphire, thereby solving the technical problems of low yield and poor uniformity of the two-dimensional MoS2 film obtained by existing mechanical peeling. 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 film comprises the following steps:

[0009] 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 the C-surface sapphire substrate placed vertically facing the airflow direction are placed in the first temperature zone, the second temperature zone and the third temperature zone of the 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-plane sapphire substrate are heated respectively 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 placed at the middle thermocouples of the corresponding temperature zones respectively.

[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 10Pa, turn off the vacuum pump, open the gas valve, and introduce 500-600sccm 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 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.

[0018] The present invention also provides a wafer-level single-layer MoS2 film prepared by the above-mentioned method for preparing a wafer-level single-layer MoS2 film.

[0019] 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.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention places the C-plane sapphire substrate vertically 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 grown MoS2 film has good uniformity.

[0022] 2. The present invention adopts a single-tube CVD tube furnace, and the gas supply system is a single gas path. The equipment is simpler than a multi-tube CVD tube furnace, and the operation is easier. In addition, the grown wafer-level MoS2 film has good uniformity and high quality.

[0023] 3. The present invention introduces a mixture of 95% argon and 5% hydrogen when growing the MoS2 film. The hydrogen serves as a reducing atmosphere, making it easier for the molybdenum element and sulfur in molybdenum trioxide to be reduced, and the two are more likely to react to obtain MoS2, thereby depositing a MoS2 film with better uniformity on the sapphire substrate.

[0024] 4. The present invention performs three-extraction and three-replenishment operations on the single-tube CVD tube furnace, that is, repeats the operation of exhausting and replenishing three times, so that the growth environment of MoS2 has a higher cleanliness, which is more conducive to the growth of high-quality and uniform MoS2 film.

[0025] In summary, the present invention prepares a wafer-level single-layer MoS2 film based on chemical vapor deposition. The film has high quality and uniform composition, and the triangular domain size is on the order of hundreds of microns. It 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 THE 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 gas, 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] Fig. 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 in conjunction with the accompanying drawings and embodiments.

[0036] A wafer-level single-layer MoS2 film, whose chemical formula is MoS2, the thickness of the wafer-level transition metal sulfide compound film is 0.6nm, that is, the single-layer MoS2 film; the single-layer MoS2 film has a wafer-level and microscopic triangular domain structure, and the size of the triangular domain 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 film comprises the following steps:

[0038] Step 1: placing sulfur powder and molybdenum trioxide powder as reaction precursors in two quartz boats respectively, and placing the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder and a 2-inch C-surface sapphire substrate placed vertically facing the airflow direction in the first temperature zone, the second temperature zone and the third temperature zone in the single-tube CVD tube furnace at the corresponding positions of the thermocouples, so as to accurately control the temperature of the sulfur powder, the molybdenum trioxide powder and the sapphire, and the distance between each other is about 50 cm; 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 can make the reaction precursors 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: Cleaning the single-tube CVD tube furnace: Seal the single-tube CVD tube furnace, and evacuate the quartz tube to remove the impurity gas inside the quartz tube. When the vacuum degree is below 10Pa, turn off the vacuum pump, open the gas valve, and slowly introduce 500-600sccm of argon until the gas 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, i.e. 1×10 5 Pa, the sulfur powder, molybdenum trioxide powder and C-plane sapphire substrate are heated respectively. After reaching the set temperature, the precursor is transported to the vicinity of the surface of the C-plane sapphire substrate under the action of the carrier gas, and the reactant is adsorbed on the substrate surface and chemically reacts to form a single-layer wafer-level MoS2 film; the carrier gas is composed of argon gas and hydrogen gas with a volume ratio of 95% and a flow rate of the carrier gas of 80 to 100 sccm. By introducing a small amount of hydrogen as a carrier gas, a reducing atmosphere is provided, which is more conducive to the chemical reaction of 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 insulation is completed, they are naturally cooled to room temperature.

[0042] Example 1

[0043] A method for preparing a wafer-level single-layer MoS2 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, and place the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder and the C-surface sapphire substrate placed vertically facing the airflow direction into the thermocouples of the first temperature zone, the second temperature zone and the third temperature zone in the 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 the impurity gas inside the quartz tube. When the vacuum degree is below 10Pa, turn off the vacuum pump, open the gas valve, and slowly introduce 500sccm 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, 80sccm of carrier gas is introduced into the single-tube CVD tube furnace, and 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-side sapphire substrate are heated respectively, and 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 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, and place the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder and the C-surface sapphire substrate placed vertically facing the airflow direction into the thermocouples of the first temperature zone, the second temperature zone and the third temperature zone in the 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 the impurity gas inside the quartz tube. When the vacuum degree is below 10Pa, turn off the vacuum pump, open the gas valve, and slowly introduce 550sccm 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, 90sccm of carrier gas is introduced into the single-tube CVD tube furnace, and 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-side sapphire substrate are heated respectively, and 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 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, and place the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder and the C-surface sapphire substrate placed vertically facing the airflow direction into the thermocouples of the first temperature zone, the second temperature zone and the third temperature zone in the 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 the impurity gas inside the quartz tube. When the vacuum degree is below 10Pa, turn off the vacuum pump, open the gas valve, and slowly introduce 600sccm 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, and 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-side sapphire substrate are heated respectively, and 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; 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, and the film prepared is as follows: Figure 3As shown in (a), it can be seen that the grown C-plane sapphire substrate 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 gas, 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 lighter contrast in the middle, which indicates the uneven nucleation density, that is, molybdenum trioxide and sulfur are more likely to react to obtain MoS2 at the edge of the substrate.

[0061] Figure 3 (c) is a photo of a wafer-level single-layer MoS2 film prepared in Example 3 of the present invention. It can be seen that the wafer-level MoS2 grown has good uniformity, and the overall contrast of the C-surface sapphire is 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 obtain MoS2 requires the valence of both molybdenum and sulfur to be reduced, and hydrogen just provides reducing properties, so the reaction of molybdenum trioxide and sulfur becomes easier, thereby making the nucleation density on the substrate uniform, and the continuous and stable supply of precursor raw materials allows the MoS2 triangular domain to grow.

[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 Figure 4 (a) It can be seen that the grown MoS2 exhibits a distinct 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 microscopy 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 consistent, 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 There are 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 that the incident laser wavelength is a pump light of 1550nm, and the peak of 775nm can be clearly detected, and 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, and 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] Fig. 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 six-fold 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, and the quartz boat containing sulfur powder, the quartz boat containing molybdenum trioxide powder and the C-surface sapphire substrate placed vertically facing the airflow direction are placed in the first temperature zone, the second temperature zone and the third temperature zone of the single-tube CVD tube furnace respectively; 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-plane sapphire substrate are heated respectively to form a wafer-level single-layer MoS2 film.

2. The method for preparing a wafer-level single-layer MoS2 thin film according to claim 1, characterized in that: The mass ratio of the sulfur powder to the molybdenum trioxide powder is (800-1000):

1.

3. The method for preparing a wafer-level single-layer MoS2 thin film according to claim 1, characterized in that: 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 placed at the middle thermocouples of the corresponding temperature zones respectively.

4. The method for preparing a wafer-level single-layer MoS2 thin film according to claim 1, characterized in that: 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 10Pa, turn off the vacuum pump, open the gas valve, and introduce 500-600sccm of argon until the pressure inside the quartz tube returns to normal pressure. Repeat the above operation at least three times.

5. The method for preparing a wafer-level single-layer MoS2 thin film according to claim 1, characterized in that: The carrier gas is composed of 95% argon and 5% hydrogen in a volume ratio, and the flow rate of the carrier gas is 80-100 sccm.

6. The method for preparing a wafer-level single-layer MoS2 thin film according to claim 1, characterized in that: The heating conditions of the single-tube CVD tube furnace are: 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.

7. A wafer-level single-layer MoS2 film prepared by the method for preparing a wafer-level single-layer MoS2 film according to any one of claims 1 to 7.

8. The wafer-level single-layer MoS2 thin film according to claim 7, 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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