A wafer-level monolayer MoS2 continuous thin film, its APCVD deposition method and application

Abstract

The application discloses a wafer-level single-layer MoS2 continuous film and an APCVD film forming method and application thereof, adopts a pipe-in-pipe type APCVD pipe type furnace, and in-situ annealing of a C-A surface sapphire substrate is first carried out under a mixed atmosphere of oxygen and argon before growing the MoS2 continuous film, then the sulfur powder, the C-A surface sapphire substrate and the molybdenum trioxide powder are simultaneously heated under a mixed atmosphere of argon and hydrogen and under an argon atmosphere, a wafer-level MoS2 continuous film with a single-layer structure is successfully prepared, and the technical problem of discontinuity of a wafer-level single-layer MoS2 film prepared by an APCVD method in the prior art is solved; the wafer-level single-layer MoS2 continuous film prepared by the application has the characteristics of high quality and good uniformity, and is favorable for large-scale integration and application of two-dimensional electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of wafer-level two-dimensional semiconductor continuous thin film preparation technology, and particularly relates to a wafer-level monolayer MoS2 continuous thin film, its APCVD film formation method and application. Technical Background

[0002] Two-dimensional transition metal chalcogenides (TMDCs) have become important candidate materials for continuing Moore's Law due to their atomic-level thickness, excellent optoelectronic properties, and good thermal stability. MoS2 is the most widely studied semiconductor material among transition metal chalcogenides. It has a hexagonal lattice structure, with sulfur and molybdenum atoms connected by covalent bonds in the planes and layers connected by van der Waals forces outwards. The number of layers in MoS2 significantly affects its physicochemical 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 transitions from an indirect band gap to a direct band gap. A single layer of MoS2 is only 0.6 nm thick with a band gap of approximately 1.9 eV, exhibiting excellent optoelectronic properties, which gives it strong photoluminescence characteristics, promoting its research and application in the optoelectronic field. At the same time, single-layer MoS2 has higher carrier mobility, making it more widely used in sensors, logic memory devices, and high-efficiency field-effect transistors (FETs).

[0003] Currently, there is considerable research on the fabrication of wafer-level continuous TMDCs using LPCVD (low-pressure chemical vapor deposition). Unlike the triangular domains of TMDCs ranging from hundreds of micrometers to millimeters, continuous films have centimeter-scale film dimensions, which is more conducive to the large-scale integration and application of two-dimensional electronic devices. However, LPCVD is usually performed at relatively low pressures, thus requiring the use of a vacuum system to reduce the pressure in the reaction chamber to between 1 and 2 torr. This makes the equipment more complex and results in a slower growth rate.

[0004] Chinese invention patent application number 202411365240.1 proposes a wafer-level monolayer MoS2 thin film and its preparation method. The MoS2 thin film is prepared by a single tube APCVD (atmospheric pressure chemical vapor deposition) tube furnace. However, the prepared MoS2 thin film has a triangular domain structure and a size of only hundreds of micrometers, which is not conducive to the large-scale integration and application of two-dimensional electronic devices. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a wafer-level monolayer MoS2 continuous thin film, its APCVD film formation method, and its application. Using a tube-in-tube APCVD furnace, the CA-facet sapphire substrate is first in-situ annealed in a mixed atmosphere of oxygen and argon before growing the MoS2 continuous thin film. Then, sulfur powder, the CA-facet sapphire substrate, and molybdenum trioxide powder are simultaneously heated in a mixed atmosphere of argon and hydrogen, successfully fabricating a wafer-level MoS2 continuous thin film with a monolayer structure on a 2-inch CA-facet sapphire substrate. This solves the technical problem of discontinuity in the preparation of wafer-level monolayer MoS2 thin films using the APCVD method in the prior art. The wafer-level monolayer MoS2 continuous thin film prepared by the present invention has high quality and good uniformity, which is beneficial for the large-scale integration and application of two-dimensional electronic devices.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] An APCVD method for wafer-level monolayer MoS2 continuous thin film deposition includes the following steps:

[0008] Step 1: Place the CA-faced sapphire as the substrate vertically on the hollow quartz support with the airflow direction facing it, and then place it at the thermocouple in the third temperature zone of the tube of the tube-type APCVD tube furnace. Perform in-situ annealing in a mixed atmosphere of argon and oxygen.

[0009] Step 2: After the tube-to-tube APCVD furnace cools to room temperature, place the sulfur powder and molybdenum trioxide powder, which are the reaction precursors, at the first temperature zone thermocouple of the coarse tube and the second temperature zone thermocouple of the thin tube of the tube-to-tube APCVD furnace, respectively; the mass ratio of the sulfur powder and molybdenum trioxide powder is (20-34):1.

[0010] Step 3: Introduce argon gas into the coarse tube of the tube-to-tube APCVD furnace to clean the tube-to-tube APCVD furnace at least three times.

[0011] Step 4: After cleaning, a mixture of argon and hydrogen gas is introduced into the thin tube of the tube-to-tube APCVD furnace, and argon gas is introduced into the thick tube of the tube-to-tube APCVD furnace until the furnace pressure is at atmospheric pressure. Then, the temperature zones corresponding to sulfur powder, molybdenum trioxide and CA surface sapphire substrate are heated to form a wafer-level continuous MoS2 thin film with a single-layer structure.

[0012] In step 1, the gas flow rates of argon and oxygen are 200–300 sccm and 20–30 sccm, respectively.

[0013] The in-situ annealing operation in step 1 is as follows: the temperature is raised to 1000-1050℃ within 60 minutes and held for 3-4 hours.

[0014] In step 1, the CA facet sapphire is a CA 1° sapphire with a 1° offset angle.

[0015] In step 2, the two reaction precursors are spaced a certain distance apart from the substrate.

[0016] In step 4, the flow rates of argon and hydrogen introduced into the thin tube are 195–199 sccm and 1–5 sccm, respectively; the flow rate of argon introduced into the thick tube is 200–300 sccm.

[0017] The heating conditions of the tube-to-tube APCVD furnace in step 4 are as follows: the first temperature zone is heated to 190-200°C within 40 minutes; the second temperature zone is heated to 550-580°C within 40 minutes; and the third temperature zone is heated to 950-965°C within 40 minutes. The three temperature zones start heating simultaneously. After reaching the corresponding preset temperature, the temperature is held for 40-60 minutes. After the holding period, the furnace is allowed to cool naturally to room temperature.

[0018] The present invention also provides a wafer-level monolayer MoS2 continuous thin film prepared by the above-described APCVD film deposition method.

[0019] The wafer-level monolayer MoS2 continuous thin film is a continuous thin film with a monolayer structure and a size on the order of centimeters.

[0020] The present invention also provides an application of the above-mentioned wafer-level monolayer MoS2 continuous thin film in two-dimensional electronic devices.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. Compared with the existing LPCVD method in an oxygen atmosphere, the present invention uses a tube-in-tube APCVD tube furnace to prepare wafer-level monolayer MoS2 continuous thin films. It is carried out under atmospheric pressure, does not require a vacuum system, has simpler equipment, and has a faster growth rate. At the same time, it avoids the sulfidation effect of sulfur vapor on molybdenum trioxide powder, thereby ensuring a continuous and controllable supply of sulfur and molybdenum sources.

[0023] 2. This invention involves in-situ annealing of the CA-plane sapphire substrate in a mixed atmosphere of oxygen and argon before growing a continuous MoS2 thin film. This not only cleans the substrate surface and forms periodically arranged steps, which is conducive to the nucleation of MoS2, but also cleans the tube furnace and improves the reproducibility of the experiment.

[0024] 3. The present invention uses a hollow quartz support to place the CA-faceted sapphire substrate, which avoids excessive contact between the quartz support and the substrate, thereby improving the uniformity of the wafer-level monolayer MoS2 continuous film during the growth process.

[0025] 4. In the cleaning of the tube-to-tube APCVD tube furnace, the present invention selects to introduce a large amount of argon gas into the gas inlet of the thick tube, which avoids the situation where molybdenum trioxide powder is blown to the vicinity of the substrate under vacuum, thereby ensuring the uniformity of wafer-level monolayer MoS2 continuous film growth.

[0026] 5. This invention successfully prepared a 2-inch-scale monolayer MoS2 continuous thin film by using a tube-in-tube APCVD furnace. Compared with the preparation of two-dimensional semiconductor triangular domains, the continuous thin film has a centimeter-scale size, which is more conducive to the large-scale integration and application of two-dimensional electronic devices. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the tube-in-tube APCVD tube furnace provided by the present invention.

[0028] Figure 2 Photograph of a hollowed-out quartz support for holding a CA-faceted sapphire substrate, provided for this invention.

[0029] Figure 3 The present invention provides wafer-level monolayer MoS2 continuous thin film images and CA-plane sapphire substrate images prepared using a hollowed-out quartz support. Figure 3 (a) is a photograph of a wafer-level monolayer MoS2 continuous thin film grown on a CA-plane sapphire substrate. Figure 3 (b) is a photograph of a CA-plane sapphire substrate.

[0030] Figure 4 The photographs provided for Comparative Example 1 of the present invention include images of the MoS2 thin film prepared and the arc-shaped quartz support used, wherein... Figure 4 (a) is a photograph of a MoS2 thin film grown on a CA-plane sapphire substrate. Figure 4 (b) Photograph of the arc-shaped quartz support holding the CA-faceted sapphire substrate.

[0031] Figure 5 The photographs and optical microscope images of different regions of the multilayer MoS2 thin film prepared in Comparative Example 2 provided by the present invention are shown in the figure. Figure 5 (a) is a photograph of a multilayer MoS2 thin film grown on a CA-plane sapphire substrate. Figure 5 (b) is Figure 5 (a) Optical microscope image of the area within the red box. Figure 5 (c) is Figure 5 (a) Optical microscope image of the area within the yellow box.

[0032] Figure 6 An atomic force microscope image of the MoS2 thin film prepared in Comparative Example 3 provided for this invention.

[0033] Figure 7 This is an optical microscope image of the wafer-level monolayer MoS2 continuous thin film prepared according to the present invention, wherein, Figure 7 (a) is a uniform monolayer MoS2 continuous film. Figure 7 (b) shows a single-layer MoS2 continuous film traced by tweezers.

[0034] Figure 8 The Raman shift spectrum and photoluminescence spectrum of the wafer-level monolayer MoS2 continuous thin film prepared in this invention are shown below. Figure 8 (a) Raman shift spectra of multiple sampling points on a 2-inch MoS2 continuous thin film. Figure 8 (b) Select photoluminescence spectra of multiple sampling points on a 2-inch MoS2 continuous thin film.

[0035] Figure 9 XPS patterns of wafer-level monolayer MoS2 continuous thin films prepared according to the present invention, wherein, Figure 9 (a) is the Mo3d peak. Figure 9 (b) S2p peak. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] like Figure 3 As shown in (a), a wafer-level monolayer MoS2 continuous thin film with the chemical formula MoS2 is a continuous thin film with a monolayer structure and a size on the order of centimeters.

[0038] like Figure 1 As shown, an APCVD method for wafer-level monolayer MoS2 continuous thin film is used to prepare the film using a tube-in-tube APCVD furnace. The tube-in-tube APCVD furnace includes a coarse tube and a thin tube nested inside the coarse tube. One end of the coarse tube is provided with a coarse tube inlet 2, and one end of the thin tube is provided with a thin tube inlet 1. The coarse tube and the thin tube are divided into temperature zones according to the airflow direction, namely a first temperature zone, a second temperature zone, and a third temperature zone. Both the coarse tube and the thin tube are quartz tubes. The coarse tube has a diameter of 80 mm and a length of 1800 mm, and the thin tube has a diameter of 20 mm and a length of 850 mm.

[0039] Specifically, the steps include the following:

[0040] Step 1: Place a 2-inch diameter CA-faceted sapphire crystal as the substrate, vertically facing the airflow direction, on a hollow quartz support. Then place it at the thermocouple in the third temperature zone of the tube-type APCVD tube furnace and perform in-situ annealing in a mixed atmosphere of argon and oxygen to obtain a clean surface. The in-situ annealing operation is as follows: heat up to 1000-1050℃ within 60 minutes and hold for 3-4 hours.

[0041] The CA-faceted sapphire is a CA 1° sapphire with a 1° offset angle. The CA-faceted sapphire with the offset angle has a step in the M-axis direction. At the step, the nucleation energy of MoS2 is lower, which is more conducive to nucleation, so that MoS2 is unidirectionally aligned and forms a single crystal MoS2.

[0042] The argon and oxygen mixture is introduced into the third temperature zone of the coarse pipe through the coarse pipe inlet 2, and the flow rates of the argon and oxygen are 200-300 sccm and 20-30 sccm, respectively.

[0043] Step 2: After the tube-to-tube APCVD furnace cools to room temperature, close the valve of the gas inlet 2 of the coarse tube. Place sulfur powder and molybdenum trioxide powder as reaction precursors in two quartz boats respectively. Place the quartz boat containing sulfur powder at the thermocouple of the first temperature zone of the coarse tube, and place the quartz boat containing molybdenum trioxide powder at the thermocouple of the second temperature zone of the thin tube. The two reaction precursors are spaced a certain distance from the substrate, preferably 30 cm. The mass ratio of sulfur powder to molybdenum trioxide powder is (20-34):1.

[0044] Step 3: Seal the tube-in-tube APCVD furnace and evacuate it until the vacuum level drops below 10 Pa. Then, turn off the vacuum pump. Next, open valve 2 at the coarse tube inlet and introduce a large amount of argon gas for purging until the internal pressure of the tube-in-tube APCVD furnace returns to atmospheric pressure, i.e., 1 × 10⁻⁶ Pa. 5 When Pa, repeat the above operation at least three times;

[0045] Step 4: After the tube-to-tube APCVD furnace has been cleaned, different carrier gases are introduced into the thin inlet 1 and the thick inlet 2, respectively. The carrier gas introduced into the thin inlet 1 is a mixture of argon and hydrogen at a flow rate of 195–199 sccm and a flow rate of 1–5 sccm, respectively. The carrier gas introduced into the thick inlet 2 is argon at a flow rate of 200–300 sccm. Argon is an inert gas and does not participate in the reaction; it is only used as a transport gas. Hydrogen provides a reducing environment, which is conducive to the chemical reaction between sulfur powder and molybdenum trioxide powder. The pressure inside the tube-to-tube APCVD furnace is then set to atmospheric pressure, i.e., 1 × 10⁻⁶ m / s². 5At Pa, the temperature zones corresponding to sulfur powder, molybdenum trioxide powder and CA-face sapphire substrate are heated respectively. After reaching the set temperature, the two reaction precursors are transported to the vicinity of the CA-face sapphire substrate surface under the action of carrier gas. The reaction precursors are adsorbed on the substrate surface and undergo chemical reaction to form a wafer-level MoS2 continuous thin film with a monolayer structure.

[0046] The heating conditions of the tube-to-tube APCVD tube furnace are as follows: the first temperature zone is heated to 190-200℃ within 40 minutes; the second temperature zone is heated to 550-580℃ within 40 minutes; and the third temperature zone is heated to 950-965℃ within 40 minutes. The three temperature zones start heating simultaneously. After reaching the corresponding preset temperature, the temperature is held for 40-60 minutes. After the holding period, the furnace is allowed to cool naturally to room temperature.

[0047] Example 1

[0048] An APCVD method for wafer-level monolayer MoS2 continuous thin film deposition includes the following steps:

[0049] Step 1: Place a 2-inch diameter CA-faceted sapphire crystal as the substrate, facing the airflow direction, vertically on a hollowed-out quartz support, and then place it at the thermocouple in the third temperature zone of the tube-type APCVD tube furnace. Perform in-situ annealing in a mixed gas environment of argon and oxygen. The in-situ annealing operation is as follows: heat up to 1000℃ within 60 minutes and hold for 3 hours; the gas flow rates of argon and oxygen are 200 sccm and 20 sccm, respectively.

[0050] Step 2: After the tube-to-tube APCVD tube furnace cools down to room temperature, close the valve of the gas inlet 2 of the coarse tube, weigh 10g of sulfur powder and 0.5g of molybdenum trioxide powder as reaction precursors and place them in two quartz boats respectively. Place the quartz boat containing sulfur powder at the thermocouple of the first temperature zone of the coarse tube, and place the quartz boat containing molybdenum trioxide powder at the thermocouple of the second temperature zone of the thin tube. The two reaction precursors are spaced 30cm apart from the substrate.

[0051] Step 3: Seal the tube-to-tube APCVD tube furnace and evacuate it. When the vacuum level drops below 10 Pa, turn off the vacuum pump. Then open the valve of the gas inlet 2 of the coarse tube and introduce a large amount of argon gas for cleaning until the gas pressure inside the tube furnace returns to atmospheric pressure. Repeat the above operation three times.

[0052] Step 4: After the tube-to-tube APCVD tube furnace is cleaned, different carrier gases are introduced into the thin inlet 1 and the thick inlet 2 respectively. The carrier gas introduced into the thin inlet 1 is a mixture of 199 sccm argon and 1 sccm hydrogen, and the carrier gas introduced into the thick inlet 2 is 300 sccm argon. When the internal pressure of the tube furnace is at atmospheric pressure, the temperature zones corresponding to sulfur powder, molybdenum trioxide powder and CA-faceted sapphire substrate are heated respectively to form a wafer-level monolayer MoS2 continuous film. The first temperature zone is heated to 200°C within 40 minutes; the second temperature zone is heated to 550°C within 40 minutes; and the third temperature zone is heated to 950°C within 40 minutes. The three temperature zones are heated simultaneously. After reaching the corresponding preset temperature, they are held for 40 minutes. After the holding period, they are allowed to cool naturally to room temperature.

[0053] Example 2

[0054] An APCVD method for wafer-level monolayer MoS2 continuous thin film deposition includes the following steps:

[0055] Step 1: Place a 2-inch diameter CA-faceted sapphire crystal as the substrate, facing the airflow direction, vertically on a hollowed-out quartz support, and then place it at the thermocouple in the third temperature zone of the coarse tube of the tube-type APCVD furnace. Perform in-situ annealing in a mixed gas environment of argon and oxygen. The in-situ annealing operation is as follows: heat up to 1025℃ within 60 minutes and hold for 3.5 hours; the gas flow rates of argon and oxygen are 250 sccm and 25 sccm, respectively.

[0056] Step 2: After the tube-to-tube APCVD tube furnace cools down to room temperature, close the valve of the gas inlet 2 of the coarse tube, weigh 10g of sulfur powder and 0.4g of molybdenum trioxide powder as reaction precursors and place them in two quartz boats respectively. Place the quartz boat containing sulfur powder at the thermocouple of the first temperature zone of the coarse tube, and place the quartz boat containing molybdenum trioxide powder at the thermocouple of the second temperature zone of the thin tube. The two reaction precursors are spaced 30cm apart from the substrate.

[0057] Step 3: Seal the tube-type APCVD tube furnace and evacuate it. When the vacuum level drops below 10 Pa, turn off the vacuum pump, open the valve of the gas inlet 2 of the coarse tube, and introduce a large amount of argon gas for cleaning until the gas pressure inside the tube furnace returns to normal. Repeat the above operation three times.

[0058] Step 4: After the tube-to-tube APCVD furnace is cleaned, different carrier gases are introduced into the thin inlet 1 and the thick inlet 2 respectively. The carrier gas introduced into the thin inlet 1 is a mixture of 197.5 sccm argon and 2.5 sccm hydrogen, and the carrier gas introduced into the thick inlet 2 is 250 sccm argon. When the internal pressure of the tube furnace is at atmospheric pressure, the temperature zones corresponding to sulfur powder, molybdenum trioxide powder and CA-faceted sapphire substrate are heated respectively to form a wafer-level monolayer MoS2 continuous film. The first temperature zone is heated to 195°C within 40 minutes; the second temperature zone is heated to 560°C within 40 minutes; and the third temperature zone is heated to 960°C within 40 minutes. The three temperature zones are heated simultaneously. After reaching the corresponding preset temperature, they are held for 50 minutes. After the holding period, they are allowed to cool naturally to room temperature.

[0059] Example 3

[0060] An APCVD method for wafer-level monolayer MoS2 continuous thin film deposition includes the following steps:

[0061] Step 1: Place a 2-inch diameter CA-faceted sapphire crystal as the substrate, facing the airflow direction, vertically on a hollowed-out quartz support, and then place it at the thermocouple in the third temperature zone of the tube-type APCVD tube furnace. Perform in-situ annealing in a mixed gas environment of argon and oxygen. The in-situ annealing operation is as follows: heat up to 1050℃ within 60 minutes and hold for 4 hours; the gas flow rates of argon and oxygen are 300 sccm and 30 sccm, respectively.

[0062] Step 2: After the tube-to-tube APCVD tube furnace cools to room temperature, close the valve of the gas inlet 2 of the coarse tube, weigh 10g of sulfur powder and 0.3g of molybdenum trioxide powder as reaction precursors and place them in two quartz boats respectively. Place the quartz boat containing sulfur powder at the thermocouple of the first temperature zone of the coarse tube, and place the quartz boat containing molybdenum trioxide powder at the thermocouple of the second temperature zone of the thin tube. The two reaction precursors are spaced 30cm apart from the substrate.

[0063] Step 3: Seal the tube-type APCVD tube furnace and evacuate it. When the vacuum level drops below 10 Pa, turn off the vacuum pump, open the valve of the gas inlet 2 of the coarse tube, and introduce a large amount of argon gas for cleaning until the gas pressure inside the tube furnace returns to normal. Repeat the above operation three times.

[0064] Step 4: After the tube-to-tube APCVD tube furnace is cleaned, different carrier gases are introduced into the thin inlet 1 and the thick inlet 2 respectively. The carrier gas introduced into the thin inlet 1 is a mixture of 195 sccm argon and 5 sccm hydrogen, and the carrier gas introduced into the thick inlet 2 is 200 sccm argon. When the internal pressure of the tube furnace is at atmospheric pressure, the temperature zones corresponding to sulfur powder, molybdenum trioxide powder and CA-faceted sapphire substrate are heated respectively to form a wafer-level monolayer MoS2 continuous film. The first temperature zone is heated to 190°C within 40 minutes; the second temperature zone is heated to 580°C within 40 minutes; and the third temperature zone is heated to 965°C within 40 minutes. The three temperature zones are heated simultaneously. After reaching the corresponding preset temperature, they are held for 60 minutes. After the holding period, they are allowed to cool naturally to room temperature.

[0065] Comparative Example 1

[0066] The process and parameters of Comparative Example 1 are the same as those of Example 1, except that in step 1, the CA-facet sapphire crystal is placed perpendicularly to the airflow direction on the arc-shaped quartz support. Figure 4 As shown in (b), the bottom edge of the vertically placed CA-plane sapphire substrate is in complete contact with the arc-shaped quartz support; the MoS2 thin film prepared by Comparative Example 1, as shown in... Figure 4 As shown in (a), it can be seen that the grown MoS2 film has a distinct black arc. The position of the black arc coincides with the position of the arc-shaped quartz support. During the growth process, MoS2 tends to nucleate at the defect, resulting in a higher nucleation density at that position, thus growing a multilayered MoS2 film that appears black.

[0067] Comparative Example 2

[0068] The process and parameters of Comparative Example 2 are the same as those of Example 1, except that in step 3, after sealing the tube-to-tube APCVD tubular furnace, a large amount of argon gas is introduced through the thin inlet 1 to clean the tubular furnace; the MoS2 thin film prepared by Comparative Example 2, as shown in the figure... Figure 5 As shown in (a), there is a significant contrast difference on the 2-inch CA-plane sapphire substrate. Due to the large amount of argon gas entering through the thin inlet 1 under low pressure, molybdenum trioxide powder is blown to the vicinity and surface of the substrate by the gas flow, resulting in the growth of a non-uniform MoS2 film. This MoS2 film exhibits discontinuities and forms a multilayer structure in some areas; Figure 5 (b) It can be seen that a portion of the MoS2 thin film ( Figure 5 (a) The red box indicates a dotted discontinuous pattern on the CA-plane sapphire substrate, such as Figure 5 (c) It can be seen that a portion of the MoS2 thin film ( Figure 5(b) The yellow box shows a multi-layer structure on the CA-plane sapphire substrate.

[0069] Comparative Example 3

[0070] The process and parameters of Comparative Example 3 are the same as those of Example 1, except that the heat preservation time in step 4 is only 5 minutes; the MoS2 film prepared by Comparative Example 3, as... Figure 6 As shown, distinct MoS2 triangular domains can be observed, and these domains vary in size and are discontinuous, indicating that a continuous film cannot be grown when the holding time is less than 40 minutes. By extending the holding time to 40–60 minutes, the MoS2 triangular domains can continuously grow under a continuous supply of reaction precursors, and adjacent domains suture together, thus growing a continuous film, as shown in the figure. Figure 7 As shown in (a).

[0071] Figure 2 The image shows a hollowed-out quartz support for holding a CA-faceted sapphire substrate provided by the present invention. By reducing the contact between the substrate and the support, the nucleation density during the growth process becomes more uniform.

[0072] Figure 3 These are photographs of a wafer-level monolayer MoS2 continuous thin film and a CA-plane sapphire substrate prepared using a hollowed-out quartz support, as well as photographs of the substrate. Figure 3 (a) is a photograph of a wafer-level monolayer MoS2 continuous thin film. Figure 3 (b) is a photograph of a CA-plane sapphire substrate; by Figure 3 (b) It can be seen that the overall contrast uniformity of the CA-plane sapphire substrate is good. Figure 3 (a) It can be seen that the uniformity of the wafer-level monolayer MoS2 continuous film grown on the CA-plane sapphire substrate is also good, indicating that the wafer-level monolayer MoS2 continuous film prepared by the present invention using a hollow quartz support has high uniformity of nucleation density.

[0073] Figure 7 This is an optical microscope image of the wafer-level monolayer MoS2 continuous thin film prepared according to the present invention. Figure 7 (a) is a dense, continuous thin film with relatively uniform overall contrast, obtained by gently stroking the substrate surface with tweezers. Figure 7 (b) shows that there is a significant difference in contrast between the CA-plane sapphire substrate and the MoS2 continuous film. At the same time, the grown monolayer MoS2 continuous film reaches a size of 2 inches. Compared with the preparation of two-dimensional semiconductor triangular domains, continuous films are more conducive to the large-scale integration and application of two-dimensional electronic devices.

[0074] Figure 8The Raman shift spectrum and photoluminescence spectrum of the wafer-level monolayer MoS2 continuous thin film prepared in this invention are shown below. Figure 8 (a) Raman displacement spectra of multiple sampling points on a 2-inch MoS2 continuous film were selected. It can be seen that the Raman vibration modes at different sampling points are almost the same, indicating that the wafer-level MoS2 continuous film prepared by the present invention has high quality and good uniformity at the microscale. Figure 8 (b) Photoluminescence spectra of multiple sampling points on a 2-inch MoS2 continuous film were selected. The PL peak positions of different sampling points located at a photon energy of 1.87 eV were almost identical, indicating that the wafer-level monolayer MoS2 continuous film grown has a monolayer structure.

[0075] Figure 9 XPS patterns of wafer-level monolayer MoS2 continuous thin films prepared according to the present invention, wherein, Figure 9 (a) is the Mo3d peak. Figure 9 (b) is the S2p peak; by Figure 9 (a) It can be seen that there are strong characteristic peaks at binding energies of 232.7 eV, 229.5 eV and 226.7 eV, which correspond to Mo 3d 3 / 2 Mo 3d 5 / 2 S2p, by Figure 9 (b) It can be seen that there are strong characteristic peaks at binding energies of 162.38 eV and 163.59 eV, corresponding to S2p, respectively. 3 / 2 and S2p 1 / 2 This indicates that the precursors molybdenum and sulfur, as well as the intermediate reactants, were fully consumed.

Claims

1. An APCVD method for forming a wafer-level monolayer MoS2 continuous thin film, characterized in that, Includes the following steps: Step 1: Place the CA-faceted sapphire as the substrate, vertically facing the airflow direction, on a hollowed-out quartz support. Then, place it at the thermocouple in the third temperature zone of the coarse tube of the tube-type APCVD furnace. Under a mixed atmosphere of argon and oxygen, heat the sapphire to 1000~1050℃ within 60 minutes and maintain it for 3~4 hours for in-situ annealing. The gas flow rates of argon and oxygen are 200~300 sccm and 20~30 sccm, respectively. The CA-faceted sapphire is a CA 1° sapphire with a 1° offset angle. Step 2: After the tube-to-tube APCVD furnace cools to room temperature, place the sulfur powder and molybdenum trioxide powder, which are the reaction precursors, at the first temperature zone thermocouple of the coarse tube and the second temperature zone thermocouple of the thin tube of the tube-to-tube APCVD furnace, respectively; the mass ratio of the sulfur powder and molybdenum trioxide powder is (20~34):

1. Step 3: Introduce argon gas into the coarse tube of the tube-to-tube APCVD furnace to clean the tube-to-tube APCVD furnace at least three times. Step 4: After cleaning, a mixture of argon and hydrogen gas is introduced into the thin tube of the tube-to-tube APCVD furnace, and argon gas is introduced into the thick tube until the furnace pressure reaches atmospheric pressure. Then, the temperature zones corresponding to sulfur powder, molybdenum trioxide, and CA-surface sapphire substrate are heated to form a wafer-level continuous MoS2 thin film with a monolayer structure. The gas flow rates of argon and hydrogen introduced into the thin tube are 195~199 sccm and 1~5 sccm, respectively; the gas flow rate of argon introduced into the thick tube is 200~300 sccm. The heating conditions of the tube-to-tube APCVD tube furnace are as follows: the first temperature zone is heated to 190~200℃ within 40 minutes; the second temperature zone is heated to 550~580℃ within 40 minutes; and the third temperature zone is heated to 950~965℃ within 40 minutes. The three temperature zones start heating simultaneously. After reaching the corresponding preset temperature, the temperature is held for 40~60 minutes. After the holding period, the furnace is allowed to cool naturally to room temperature.

2. The APCVD film formation method for a wafer-level monolayer MoS2 continuous thin film according to claim 1, characterized in that: In step 2, the two reaction precursors are spaced a certain distance apart from the substrate.

3. The wafer-level monolayer MoS2 continuous thin film prepared by the APCVD film deposition method according to any one of claims 1 or 2.

4. The wafer-level monolayer MoS2 continuous thin film according to claim 3, characterized in that: The wafer-level monolayer MoS2 continuous thin film is a continuous thin film with a monolayer structure and a size on the order of centimeters.

5. The application of the wafer-level monolayer MoS2 continuous thin film according to claim 4 in two-dimensional electronic devices.

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