Wafer-level single-layer MoS2 continuous film and APCVD film forming method and application thereof

Abstract

The invention discloses a wafer-level single-layer MoS2 continuous film and an APCVD film forming method and application thereof.The wafer-level single-layer MoS2 continuous film is obtained by adopting a pipe-in-pipe APCVD tubular furnace, and conducting in-situ annealing on a C-A face sapphire substrate in the mixed atmosphere of oxygen and argon before the MoS2 continuous film grows; then the sulfur powder and the C-A surface sapphire substrate are heated at the same time in the mixed atmosphere of argon and hydrogen, the molybdenum trioxide powder is heated at the same time in the argon atmosphere, the wafer-level MoS2 continuous thin film of a single-layer structure is successfully prepared, and the technical problem that in the prior art, the wafer-level single-layer MoS2 thin film prepared through an APCVD method is discontinuous is solved. The wafer-level single-layer MoS2 continuous film prepared by the method has the characteristics of high quality and good uniformity, and is beneficial to large-scale integration and application of two-dimensional electronic devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of wafer-level two-dimensional semiconductor continuous thin film preparation, and in particular relates to a wafer-level single-layer MoS 2 Continuous thin films and their APCVD film forming methods and applications. Technical Background

[0002] Two-dimensional transition metal dichalcogenides (TMDCs) have become one of the important candidate materials for continuing Moore's Law due to their atomic-level thickness, excellent optoelectronic properties and good thermal stability. 2 It 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. 2 The number of layers will significantly affect its physical and chemical properties. As the number of layers decreases from multiple layers to a single layer or even a single layer, MoS 2 The optical band gap of MoS increases gradually and changes from an indirect band gap to a direct band gap. 2 The thickness is only 0.6nm, the band gap is about 1.9eV, and it has excellent photoelectric properties, which makes it have strong photoluminescence characteristics, promoting its research and application in the field of optoelectronics. 2 It has higher carrier mobility, which makes it more widely used in sensors, logic storage devices, high-efficiency field effect transistors (FETs) and other fields.

[0003] At present, there have been many studies on the use of LPCVD (low-pressure chemical vapor deposition) to prepare wafer-level TMDCs continuous films. Different from the TMDCs triangular domains of hundreds of microns to millimeters, the continuous film has a film size of centimeters, which is more conducive to the large-scale integration and application of two-dimensional electronic devices. However, LPCVD is usually carried out at a lower pressure, so a vacuum system is required to reduce the pressure of the reaction chamber to between 1-2 torr, the equipment is more complex, and the growth rate is slower.

[0004] The Chinese invention patent application number 202411365240.1 proposes a wafer-level single-layer MoS 2 Thin film and preparation method thereof, using a single-tube APCVD (atmospheric pressure chemical vapor deposition) tube furnace to prepare MoS 2 Thin film, but the prepared MoS 2 The film has a triangular domain structure and is only hundreds of microns in size, which is not conducive to the large-scale integration and application of two-dimensional electronic devices. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the present invention aims to provide a wafer-level single-layer MoS2 Continuous thin film and APCVD film forming method and application thereof, using a tube-in-tube APCVD tube furnace, by growing MoS 2 Before continuous film formation, the CA-surface sapphire substrate was first annealed in situ in a mixed atmosphere of oxygen and argon. Then, the sulfur powder and the CA-surface sapphire substrate were heated simultaneously in a mixed atmosphere of argon and hydrogen, and the molybdenum trioxide powder was heated in an argon atmosphere. A wafer-level MoS with a single-layer structure was successfully prepared on a 2-inch CA-surface sapphire. 2 Continuous film, which solves the problem of APCVD method in the prior art for preparing wafer-level single-layer MoS 2 Technical problems of film discontinuity; Wafer-level single-layer MoS prepared by the present invention 2 Continuous films have the characteristics of high quality and good uniformity, which is conducive to the large-scale integration and application of two-dimensional electronic devices.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0007] A wafer-level single-layer MoS 2 The APCVD film forming method of a continuous thin film comprises the following steps:

[0008] Step 1: Place the CA-surface sapphire as the substrate vertically on a hollow quartz support facing the direction of gas flow, and then place it at the third temperature zone thermocouple of the tube-in-tube APCVD tube furnace, and perform in-situ annealing in a mixed atmosphere of argon and oxygen;

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

[0010] Step 3: introducing argon gas into the thick tube of the tube-in-tube APCVD tube furnace to clean the tube-in-tube APCVD tube furnace at least three times;

[0011] Step 4: After cleaning is completed, a mixed gas of argon and hydrogen is introduced into the thin tube of the tube-in-tube APCVD tube furnace, and argon is introduced into the thick tube of the tube-in-tube APCVD tube furnace until the pressure in the furnace is at normal pressure. Then, the temperature zones corresponding to the sulfur powder, molybdenum trioxide and CA-surface sapphire substrate are heated respectively to form a wafer-level MoS with a single-layer structure. 2 Continuous film.

[0012] In the 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: heating to 1000-1050° C. within 60 minutes and maintaining the temperature for 3-4 hours.

[0014] The CA plane sapphire in step 1 is a CA 1° sapphire with a miscut angle of 1°.

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

[0016] In step 4, 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.

[0017] The heating conditions of the tube-in-tube APCVD tube 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; the third temperature zone is heated to 950-965°C within 40 minutes, and the three temperature zones are heated simultaneously. After reaching the corresponding preset temperature, they are kept warm for 40-60 minutes. After the insulation is completed, they are naturally cooled to room temperature.

[0018] The present invention also provides a wafer-level single-layer MoS prepared by the above-mentioned APCVD film forming method. 2 Continuous film.

[0019] The wafer-level single-layer MoS 2 The continuous film is a continuous film having a single-layer structure and a size of the order of centimeters.

[0020] The present invention also provides a wafer-level single-layer MoS 2 Application of continuous thin films in two-dimensional electronic devices.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Compared with the LPCVD method in oxygen atmosphere in the prior art, the present invention adopts a tube-in-tube APCVD tube furnace to prepare wafer-level single-layer MoS 2 The continuous film is produced under atmospheric pressure, does not require a vacuum system, has simpler equipment, and has a faster growth rate; at the same time, the sulfurization effect of sulfur vapor on molybdenum trioxide powder is avoided, thereby ensuring a continuous and controllable supply of sulfur and molybdenum sources.

[0023] 2. The present invention is achieved by growing MoS 2 Before forming the continuous film, the CA-surface sapphire substrate is in-situ annealed in a mixed atmosphere of oxygen and argon, which can not only clean the substrate surface and form periodically arranged steps, but also facilitate the formation of MoS 2It not only cleans the tube furnace, but also improves the repeatability of the experiment.

[0024] 3. The present invention adopts a hollow quartz support to place the CA-surface sapphire substrate, avoiding excessive contact between the quartz support and the substrate, thereby improving the wafer-level single-layer MoS during the growth process. 2 Uniformity of continuous films.

[0025] 4. When cleaning the tube-in-tube APCVD tube furnace, the present invention selects to introduce a large amount of argon gas into the thick tube inlet, thereby avoiding the situation where the molybdenum trioxide powder is blown to the vicinity of the substrate by the gas under vacuum, thereby ensuring the wafer-level single-layer MoS 2 Uniformity of continuous thin film growth.

[0026] 5. The present invention successfully prepared a 2-inch single-layer MoS by using a tube-in-tube APCVD tube furnace. 2 Compared with the preparation of two-dimensional semiconductor triangular domains, continuous films have centimeter-level sizes, which are more conducive to the large-scale integration and application of two-dimensional electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 2 This is a photo of the hollow quartz support for holding the CA-plane sapphire substrate provided by the present invention.

[0029] Figure 3 The wafer-level single-layer MoS prepared by the hollow quartz support provided by the present invention 2 Continuous film photos and CA surface sapphire substrate photos, among which, Figure 3 (a) Wafer-level monolayer MoS grown on CA-surface sapphire substrate 2 Continuous film photos, Figure 3 (b) is a photo of CA-surface sapphire substrate.

[0030] Figure 4 MoS prepared in Comparative Example 1 provided by the present invention 2 Photos of the film and the arc-shaped quartz support used, among which, Figure 4 (a) MoS grown on CA-surface sapphire substrate 2 Film photos, Figure 4 (b) is a photo of the arc-shaped quartz holder holding the CA-plane sapphire substrate.

[0031] Figure 5 The multilayer MoS prepared in Comparative Example 2 provided by the present invention 2Film photos and optical micrographs of different regions, where Figure 5 (a) Multilayer MoS grown on CA-surface sapphire substrate 2 Film photos, Figure 5 (b) Figure 5 (a) Optical microscopy image of the red frame area. Figure 5 (c) Figure 5 (a) Optical microscopy image of the yellow framed area.

[0032] Figure 6 MoS prepared in Comparative Example 3 provided by the present invention 2 Atomic force microscopy image of the film.

[0033] Figure 7 The wafer-level single-layer MoS prepared by the present invention 2 Optical microscope image of a continuous film, where Figure 7 (a) is a uniform single-layer MoS 2 Continuous film, Figure 7 (b) A single layer of MoS is scratched by tweezers 2 Continuous film.

[0034] Figure 8 The wafer-level single-layer MoS prepared by the present invention 2 Raman shift spectrum and photoluminescence spectrum of continuous film, among which, Figure 8 (a) Select 2-inch MoS 2 Raman shift maps of multiple sampling points on a continuous film, Figure 8 (b) Select 2-inch MoS 2 Photoluminescence spectra of multiple sampling points on a continuous film.

[0035] Fig. 9 The wafer-level single-layer MoS prepared by the present invention 2 XPS spectrum of continuous film, where Fig. 9 (a) is the Mo3d peak, Fig. 9 (b) S2p peak. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] like Figure 3 (a) shows a wafer-level single-layer MoS 2 A continuous film with the chemical formula MoS 2 , the wafer-level single-layer MoS 2 The continuous film is a continuous film having a single-layer structure and a size of the order of centimeters.

[0038] like Figure 1As shown, a wafer-level single-layer MoS 2 The APCVD film forming method of a continuous thin film adopts a tube-in-tube APCVD tube furnace for preparation, wherein the tube-in-tube APCVD tube furnace comprises a thick tube and a thin tube nested in the thick tube, a thick tube air inlet 2 is provided at one end of the thick tube, and a thin tube air inlet 1 is provided at one end of the thin tube, and the thick tube and the thin tube are divided into temperature zones according to the flow direction of airflow, namely, a first temperature zone, a second temperature zone and a third temperature zone; the thick tube and the thin tube are both quartz tubes, the diameter of the thick tube is 80 mm, the length is 1800 mm, and the diameter of the thin tube is 20 mm, and the length is 850 mm;

[0039] The specific steps include:

[0040] Step 1: Place a 2-inch diameter CA-surface sapphire substrate as a substrate and place it vertically on a hollow quartz support facing the direction of gas flow, and then place it at the third temperature zone thermocouple of the thick tube of the tube-in-tube 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: heating to 1000-1050° C. within 60 minutes and maintaining for 3-4 hours;

[0041] The CA-surface sapphire is a CA 1° sapphire with a miscut angle of 1°. The CA-surface sapphire with a miscut angle has steps in the M-axis direction. 2 The nucleation energy of MoS is lower, which is more conducive to nucleation. 2 Unidirectional arrangement to form single crystal MoS 2 ;

[0042] The mixed gas of argon and oxygen is introduced into the third temperature zone of the thick tube through the thick tube gas inlet 2, and the gas flow rates of the argon and oxygen are 200-300 sccm and 20-30 sccm respectively;

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

[0044] Step 3: Seal the tube-in-tube APCVD tube furnace and evacuate the tube-in-tube APCVD tube furnace until the vacuum degree drops below 10Pa, then turn off the vacuum pump; then open the valve 2 of the thick tube inlet, and introduce a large amount of argon gas for cleaning until the internal pressure of the tube-in-tube APCVD tube furnace returns to normal pressure, that is, 1×105 When Pa, repeat the above operation at least three times;

[0045] Step 4: After the cleaning of the tube-in-tube APCVD tube furnace is completed, different carrier gases are introduced into the thin tube inlet 1 and the thick tube inlet 2 respectively. The carrier gas introduced into the thin tube inlet 1 is a mixed gas of argon with a gas flow rate of 195-199 sccm and hydrogen with a gas flow rate of 1-5 sccm, and the carrier gas introduced into the thick tube inlet 2 is argon with a gas flow rate of 200-300 sccm. Argon is an inert gas and does not participate in the reaction but is only used as a transport gas. Hydrogen also provides a reducing environment, which is conducive to the chemical reaction between sulfur powder and molybdenum trioxide powder. The furnace pressure of the tube-in-tube APCVD tube furnace is at normal pressure, that is, 1×10 5 When the temperature of sulfur powder, molybdenum trioxide powder and CA-surface sapphire substrate is 1.37 Pa, the temperature zones corresponding to sulfur powder, molybdenum trioxide powder and CA-surface sapphire substrate are heated respectively. When the set temperature is reached, the two reaction precursors are transported to the surface of CA-surface sapphire substrate under the action of carrier gas. The reaction precursors are adsorbed on the substrate surface and chemically react to form wafer-level MoS with a single-layer structure. 2 Continuous film;

[0046] The heating conditions of the tube-in-tube APCVD tube furnace 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; the third temperature zone is heated to 950-965°C within 40 minutes. The three temperature zones start heating at the same time. After reaching the corresponding preset temperature, they are kept warm for 40-60 minutes. After the insulation is completed, they are naturally cooled to room temperature.

[0047] Example 1

[0048] A wafer-level single-layer MoS 2 The APCVD film forming method of a continuous thin film comprises the following steps:

[0049] Step 1: Place a 2-inch diameter CA-surface sapphire substrate as a substrate and place it vertically on a hollow quartz support facing the direction of gas flow, and then place it at the third temperature zone thermocouple of the thick tube of the tube-in-tube APCVD tube furnace, and perform in-situ annealing in a mixed gas environment of argon and oxygen; the in-situ annealing operation is: heating to 1000°C within 60 minutes and maintaining for 3 hours; the gas flow rates of argon and oxygen are 200 sccm and 20 sccm respectively;

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

[0051] Step 3: Seal the tube-in-tube APCVD tube furnace and evacuate it. When the vacuum degree drops below 10Pa, turn off the vacuum pump; then open the valve of the thick tube air inlet 2 and introduce a large amount of argon gas for cleaning until the internal pressure of the tube furnace returns to normal pressure. Repeat the above operation three times;

[0052] Step 4: After the tube-in-tube APCVD tube furnace is cleaned, different carrier gases are introduced into the thin tube inlet 1 and the thick tube inlet 2 respectively. The carrier gas introduced into the thin tube inlet 1 is a mixed gas of 199sccm argon and 1sccm hydrogen, and the carrier gas introduced into the thick tube inlet 2 is 300sccm argon. When the internal pressure of the tube furnace is at normal pressure, the temperature zones corresponding to the sulfur powder, molybdenum trioxide powder and CA-surface sapphire substrate are heated respectively to form a wafer-level single-layer MoS 2 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; the third temperature zone is heated to 950°C within 40 minutes, and the three temperature zones start heating at the same time. After reaching the corresponding preset temperature, they are kept warm for 40 minutes. After the insulation ends, they are naturally cooled to room temperature.

[0053] Example 2

[0054] A wafer-level single-layer MoS 2 The APCVD film forming method of a continuous thin film comprises the following steps:

[0055] Step 1: Place a 2-inch diameter CA-surface sapphire substrate as a substrate, facing the direction of gas flow, vertically on a hollow quartz support, and then place it at the third temperature zone thermocouple of the thick tube of the tube-in-tube APCVD tube furnace, and perform in-situ annealing in a mixed gas environment of argon and oxygen; the in-situ annealing operation is: heating to 1025°C within 60 minutes and maintaining for 3.5 hours; the gas flow rates of argon and oxygen are 250sccm and 25sccm respectively;

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

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

[0058] Step 4: After the tube-in-tube APCVD tube furnace is cleaned, different carrier gases are introduced into the thin tube inlet 1 and the thick tube inlet 2 respectively. The carrier gas introduced into the thin tube inlet 1 is a mixed gas of 197.5sccm argon and 2.5sccm hydrogen, and the carrier gas introduced into the thick tube inlet 2 is 250sccm argon; when the internal pressure of the tube furnace is at normal pressure, the temperature zones corresponding to the sulfur powder, molybdenum trioxide powder and CA-surface sapphire substrate are heated respectively to form a wafer-level single-layer MoS 2 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; the third temperature zone is heated to 960°C within 40 minutes, and the three temperature zones start heating at the same time. After reaching the corresponding preset temperature, they are kept warm for 50 minutes. After the insulation ends, they are naturally cooled to room temperature.

[0059] Example 3

[0060] A wafer-level single-layer MoS 2 The APCVD film forming method of a continuous thin film comprises the following steps:

[0061] Step 1: Place a 2-inch diameter CA-surface sapphire substrate as a substrate and place it vertically on a hollow quartz support facing the direction of gas flow, and then place it at the third temperature zone thermocouple of the thick tube of the tube-in-tube APCVD tube furnace, and perform in-situ annealing in a mixed gas environment of argon and oxygen; the in-situ annealing operation is: heating to 1050°C within 60 minutes and maintaining for 4 hours; the gas flow rates of argon and oxygen are 300 sccm and 30 sccm respectively;

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

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

[0064] Step 4: After the tube-in-tube APCVD tube furnace is cleaned, different carrier gases are introduced into the thin tube inlet 1 and the thick tube inlet 2 respectively. The carrier gas introduced into the thin tube inlet 1 is a mixed gas of 195sccm argon and 5sccm hydrogen, and the carrier gas introduced into the thick tube inlet 2 is 200sccm argon; when the internal pressure of the tube furnace is at normal pressure, the temperature zones corresponding to the sulfur powder, molybdenum trioxide powder and CA-surface sapphire substrate are heated respectively to form a wafer-level single-layer MoS 2 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; the third temperature zone is heated to 965°C within 40 minutes, and the three temperature zones start heating at the same time. After reaching the corresponding preset temperature, they are kept warm for 60 minutes. After the insulation ends, they are naturally cooled to room temperature.

[0065] Comparative Example 1

[0066] The process and parameters of this comparative example 1 are the same as those of the embodiment 1, except that in step 1, the CA-surface sapphire is placed vertically on the arc-shaped quartz support in the direction of air flow. Figure 4 As shown in (b), the bottom edge of the vertically placed CA-surface sapphire substrate is in full contact with the arc-shaped quartz support; the MoS prepared in Comparative Example 1 2 Thin films, such as Figure 4 As shown in (a), it can be seen that the grown MoS 2 There is an obvious black arc in the film, and the position of the black arc coincides with the contact position of the arc-shaped quartz support. 2 It is more inclined to nucleate at the defect, so the nucleation density is higher at this location, and multilayer MoS is grown. 2 Thin film, black in color.

[0067] Comparative Example 2

[0068] The process and parameters of this comparative example 2 are the same as those of Example 1, except that: after the tube-in-tube APCVD tube furnace is sealed in step 3, a large amount of argon gas is introduced into the tube inlet 1 to clean the tube furnace; the MoS prepared in comparative example 2 2 Thin films, such as Figure 5 As shown in (a), there is an obvious contrast difference on the 2-inch CA-surface sapphire substrate. Under low pressure, a large amount of argon gas enters the capillary inlet 1, causing the molybdenum trioxide powder to be blown to the vicinity and surface of the substrate under the action of the gas flow, thereby growing non-uniform MoS 2 The MoS film 2 The film showed discontinuity and some areas formed a multilayer structure; e.g. Figure 5 (b) It can be seen that the MoS 2 Part of the film area ( Figure 5 The red frame in (a) shows a point-like discontinuity on the CA-surface sapphire substrate, such as Figure 5 (c) It can be seen that the MoS 2 Part of the film area ( Figure 5 The yellow box in (b) shows a multilayer structure on a 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 holding time in step 4 is only 5 min; the MoS prepared in Comparative Example 3 2 Thin films, such as Figure 6 As shown, we can see obvious MoS 2 triangular domain, and the MoS 2 The sizes of the triangular domains vary and are discontinuous, indicating that a continuous film cannot be grown when the holding time is less than 40 min. By extending the holding time to 40-60 min, MoS 2 The triangular domains can continue to grow under the continuous supply of reaction precursors, and the adjacent triangular domains are sutured with each other, thereby growing a continuous film, such as Figure 7 (a) shown.

[0071] Figure 2 A photo of the hollow quartz support for holding a CA-plane sapphire substrate provided by the present invention. Since the contact between the substrate and the support is reduced, the nucleation density during the growth process is more uniform.

[0072] Figure 3 The present invention uses a hollow quartz support to prepare a wafer-level single-layer MoS 2 Continuous film photos and CA surface sapphire substrate photos, among which, Figure 3 (a) Wafer-level single-layer MoS2 Continuous film photos, Figure 3 (b) is a photo of a CA-surface sapphire substrate; Figure 3 (b) It can be seen that the overall contrast uniformity of the CA surface sapphire substrate is good. Figure 3 (a) It can be seen that the wafer-level single-layer MoS grown on the CA-surface sapphire substrate 2 The uniformity of the continuous film is also good, indicating that the present invention uses a hollow quartz support to prepare a wafer-level single-layer MoS 2 Continuous film with high uniformity of nucleation density.

[0073] Figure 7 The wafer-level single-layer MoS prepared by the present invention 2 Optical microscopy of continuous films. Figure 7 (a) is a dense continuous film with a relatively uniform contrast. It is obtained by gently scratching the substrate surface with tweezers. Figure 7 (b), it can be seen that the CA surface sapphire substrate and MoS 2 The contrast of the continuous film is obviously different; at the same time, the grown single-layer MoS 2 The size of the continuous film reaches 2 inches. Compared with the preparation of two-dimensional semiconductor triangular domains, the continuous film is more conducive to the large-scale integration and application of two-dimensional electronic devices.

[0074] Figure 8 The wafer-level single-layer MoS prepared by the present invention 2 Raman shift spectrum and photoluminescence spectrum of continuous film, among which, Figure 8 (a) Select 2-inch MoS 2 The Raman shift spectra of multiple sampling points on the continuous film show that the Raman vibration modes at different sampling points are almost the same, indicating that the wafer-level MoS prepared by the present invention 2 High quality of continuous films and good uniformity on a microscopic scale; Figure 8 (b) Select 2-inch MoS 2 Photoluminescence spectra of multiple sampling points on the continuous film, where the PL peaks of different sampling points at the photon energy of 1.87 eV are almost the same, indicating that the grown wafer-level single-layer MoS 2 The continuous film has a single-layer structure.

[0075] Fig. 9 The wafer-level single-layer MoS prepared by the present invention 2 XPS spectrum of continuous film, where Fig. 9 (a) is the Mo3d peak, Fig. 9 (b) is the S2p peak; Fig. 9(a) It can be seen that there are strong characteristic peaks at the binding energies of 232.7 eV, 229.5 eV and 226.7 eV, corresponding to Mo 3d 3 / 2 ,Mo 3d 5 / 2 , S2p, by Fig. 9 (b) It can be seen that there are strong characteristic peaks at the binding energies of 162.38 eV and 163.59 eV, corresponding to S2p 3 / 2 and S2p 1 / 2 , indicating that the reaction precursors molybdenum and sulfur as well as the intermediate reactants were fully consumed.

Claims

1. An APCVD film forming method for a wafer-level single-layer MoS2 continuous thin film, characterized in that: The steps include: Step 1: Place the CA-surface sapphire as the substrate vertically on a hollow quartz support facing the direction of gas flow, and then place it at the third temperature zone thermocouple of the tube-in-tube APCVD tube furnace, and perform in-situ annealing in a mixed atmosphere of argon and oxygen; Step 2: After the tube-in-tube APCVD tube furnace is cooled to room temperature, sulfur powder and molybdenum trioxide powder as reaction precursors are placed at the first temperature zone thermocouple of the thick tube and the second temperature zone thermocouple of the thin tube of the tube-in-tube APCVD tube furnace respectively; the mass ratio of the sulfur powder to the molybdenum trioxide powder is (20-34):1; Step 3: introducing argon gas into the thick tube of the tube-in-tube APCVD tube furnace to clean the tube-in-tube APCVD tube furnace at least three times; Step 4: After cleaning is completed, a mixed gas of argon and hydrogen is introduced into the thin tube of the tube-in-tube APCVD tube furnace, and argon is introduced into the thick tube of the tube-in-tube APCVD tube furnace until the pressure in the furnace is at normal pressure. Then, the temperature zones corresponding to the sulfur powder, molybdenum trioxide and CA-surface sapphire substrate are heated respectively to form a wafer-level MoS2 continuous thin film with a single-layer structure.

2. The APCVD film forming method of a wafer-level single-layer MoS2 continuous thin film according to claim 1, characterized in that: In the step 1, the gas flow rates of argon and oxygen are 200-300 sccm and 20-30 sccm respectively.

3. The APCVD film forming method of a wafer-level single-layer MoS2 continuous thin film according to claim 1, characterized in that: The in-situ annealing operation in step 1 is: heating to 1000-1050° C. within 60 minutes and maintaining the temperature for 3-4 hours.

4. The APCVD film forming method of a wafer-level single-layer MoS2 continuous thin film according to claim 1, characterized in that: The CA plane sapphire in step 1 is a CA 1° sapphire with a miscut angle of 1°.

5. The APCVD film forming method of a wafer-level single-layer MoS2 continuous thin film according to claim 1, characterized in that: In step 2, the two reaction precursors and the substrate are spaced a certain distance apart from each other.

6. The APCVD film forming method of a wafer-level single-layer MoS2 continuous thin film according to claim 1, characterized in that: In step 4, 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.

7. The APCVD film forming method of a wafer-level single-layer MoS2 continuous thin film according to claim 1, characterized in that: The heating conditions of the tube-in-tube APCVD tube 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; the third temperature zone is heated to 950-965°C within 40 minutes, and the three temperature zones are heated simultaneously. After reaching the corresponding preset temperature, they are kept warm for 40-60 minutes. After the insulation is completed, they are naturally cooled to room temperature.

8. A wafer-level single-layer MoS2 continuous thin film prepared by the APCVD film forming method of a wafer-level single-layer MoS2 continuous thin film according to any one of claims 1-7.

9. The wafer-level single-layer MoS2 continuous thin film according to claim 8, characterized in that: The wafer-level single-layer MoS2 continuous film is a continuous film with a single-layer structure, and the size is in the order of centimeters.

10. Application of the wafer-level single-layer MoS2 continuous film according to claim 9 in two-dimensional electronic devices.

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