Large-area molybdenum disulfide film and preparation method thereof
By pretreating the molybdenum source with ammonia and combining it with CVD, a large-area molybdenum disulfide film was prepared, which solved the problems of uneven and discontinuous growth of MoS2 films in the prior art and realized the mass production of high-quality MoS2 films.
Patent Information
- Application Number
- CN202510954897.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-11-07
AI Technical Summary
Existing technologies make it difficult to achieve mass production of large-area, uniform two-dimensional layered MoS2 films, especially due to problems such as uneven film thickness, pores, and discontinuities during CVD growth.
A modified molybdenum source coating was prepared by pretreating the molybdenum source with ammonia water and then vacuum drying. A large-area molybdenum disulfide film was then grown in a dual-temperature zone tube furnace by CVD, and the reaction conditions were controlled to improve uniformity and crystal quality.
This method enables the growth of large-area, uniform, and continuous MoS2 thin films, improving the crystallization quality and growth controllability of the films and solving the problems of uneven thickness and discontinuity in traditional methods.
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Figure CN120905644A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of molybdenum disulfide preparation, in particular to a large-area molybdenum disulfide film and a preparation method thereof. BACKGROUND
[0002] Molybdenum disulfide (MoS2) is one of the typical representatives of two-dimensional transition metal sulfides, which has the advantages of adjustable band gap, good mechanical flexibility, high carrier mobility, high photoelectric conversion efficiency, etc., and has shown great potential in electronic devices and optoelectronic devices. However, in order to utilize the excellent photoelectric properties and semiconductor properties of MoS2 for application in the field of photoelectric detection and new electronic devices, it is necessary to explore the large-scale and controllable (controllable number of layers, controllable morphology, and controllable growth area) production technology of high-quality two-dimensional layered MoS2 thin films.
[0003] At present, the methods widely recognized in the industry for preparing high-quality and large-area two-dimensional layered MoS2 are mainly pyrolysis and chemical vapor deposition or improvements based on the two methods. The pyrolysis method first decomposes the raw material at high temperature under a hydrogen (H2) atmosphere to obtain MoS3, and then thermally decomposes MoS3 under vacuum to obtain a MoS2 film. However, due to the presence of many uncontrollable parameters in the reaction process, there are still great challenges in industrial production.
[0004] However, as a mainstream method for preparing large-area and high-quality MoS2 films, the chemical vapor deposition (CVD) method simply involves the deposition of MoS2 on a substrate after a series of reactions between a sulfur source and a molybdenum source under the protection of an inert gas at a high temperature (700-800°C). Elemental sulfur is commonly used as the sulfur source, and molybdenum trioxide (MoO3) is generally used as the molybdenum source. The advantages of this method include strong controllability of reaction parameters such as reaction temperature, reaction time, reaction gas pressure, and carrier gas flow rate, which are inherently advantageous for the preparation of layered MoS2 with controllable size and thickness, making it highly promising for industrial production. However, the CVD method for growing MoS2 still has some limitations, especially in terms of uniformity and large size, as it is prone to problems such as uneven MoS2 film thickness, holes, and discontinuity. People have tried various methods to improve the large-area and uniformity of CVD-grown MoS2, but they are often limited by expensive equipment or complex operations. Therefore, there is an urgent need for a simple and feasible method to achieve the batch production of large-area and uniformly good MoS2. SUMMARY
[0005] The present application provides a large-area molybdenum disulfide film and a preparation method thereof. The molybdenum source is pretreated with ammonia water, and a modified molybdenum source coating is obtained through vacuum drying. On the basis of the uniform coating, a uniform and continuous large-size MoS2 film is synthesized by the CVD method.
[0006] The technical scheme of the present application is implemented as follows: a preparation method of a large-area molybdenum disulfide film, comprising the following steps: (1) adding NaCl into an ammonia solution, mixing uniformly under ultrasonic vibration to obtain a mixed solution 1, wherein the NaCl is used as a growth catalyst to increase the saturated vapor pressure of a reaction source; (2) adding MoO3 into the mixed solution 1, mixing uniformly under ultrasonic vibration to obtain a mixed solution 2; (3) drying the mixed solution 2 to obtain a modified molybdenum source coating; (4) placing a substrate towards the modified molybdenum source coating, spacing the substrate and the modified molybdenum source coating, and then placing the substrate in a high-temperature zone of a double-temperature-zone tube furnace and placing sulfur powder in a low-temperature zone of the double-temperature-zone tube furnace, and using a CVD method to prepare a large-area molybdenum disulfide film.
[0007] Further, the method for preparing the large-area molybdenum disulfide film by using the CVD method is as follows: After the double-temperature-zone tube furnace is vacuumized, nitrogen is introduced into the furnace until the pressure in the furnace is restored to normal pressure, and the process is repeated for multiple times to eliminate the influence of air; nitrogen is used as a carrier gas, and a constant flow rate of 80-100 sccm is maintained; the modified molybdenum source coating is gradually heated to 720-750°C at a speed of 20-30°C / min, and then maintained at the temperature; after the modified molybdenum source coating reaches the specified temperature, the sulfur powder is heated to 160-180°C at a speed of 45-55°C / min, the growth process lasts for 10-20 min, and then the system is naturally cooled to room temperature.
[0008] Further, the spacing distance between the high-temperature zone and the low-temperature zone is 25-40 cm.
[0009] Further, the modified molybdenum source coating is heated to 730°C, and the sulfur powder is heated to 170°C.
[0010] Further, in step (1), the amount of NaCl is 1 mg, and the amount of the ammonia solution is 5-20 ml, such as 5 ml, 10 ml, 15 ml, 20 ml, and the like; in step (2), the amount of MoO3 is 10 mg, and the amount of the mixed solution 1 is 5-20 ml, such as 5 ml, 10 ml, 15 ml, 20 ml, and the like.
[0011] Further, in step (3), the drying temperature of the mixed solution 2 is 50-80°C, such as 50°C, 60°C, 70°C, 80°C, and the like, until the water is fully volatilized.
[0012] Further, in step (3), the temperature for drying the mixed solution 2 is 60°C. Different drying temperatures result in different uniformity of the obtained coating: too low a drying temperature will greatly extend the drying time and reduce production efficiency; too high a drying temperature will cause the water and process ammonia to evaporate too quickly, reducing the uniformity of the coating, and the molybdenum source coating obtained by drying at 60°C has the best uniformity.
[0013] Further, in step (4), the interval between the substrate and the modified molybdenum source coating is 1.5-2.5 cm.
[0014] Further, in step (4), the substrate is SiO2 / Si, and the SiO2 faces the modified molybdenum source coating.
[0015] A large-area molybdenum disulfide film prepared by the preparation method.
[0016] The beneficial effects of the present application are as follows: The present application pretreats the reaction source MoO3 with ammonia water, and then uses a CVD method to prepare a large-size, uniform MoS2 film. In the present application, the MoO3 is pretreated with ammonia water (NH3-H2O, ~25 wt%) to obtain a modified molybdenum source uniformly distributed at the bottom of a quartz boat. Compared with the traditional growth method in which the reaction molybdenum source is accumulated at a point, this pretreatment method greatly improves the spatial distribution uniformity of the molybdenum source during the growth process. In addition, after the pretreatment, the reaction between ammonia water and MoO3 generates (NH4)2Mo2O7 and (NH4)2Mo3O 10 intermediate compounds, but in the CVD growth process, the intermediate compounds gradually decompose into NH3 and H2O. However, the gaseous H2O molecules can promote the volatilization of molybdenum oxide to some extent, and NH3 can provide a reducing atmosphere to prevent the presence of oxygen. Therefore, the pretreatment of the molybdenum source with ammonia water can greatly improve the uniformity and crystalline quality of the grown MoS2. BRIEF DESCRIPTION OF DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.
[0018] Figure 1 The method flowchart of the present application; Figure 2The images are optical micrographs of MoS2 thin films. (a) is an optical photograph of MoS2 in Comparative Example 1, (b) is a magnified micrograph of a portion of Figure (a), (c) is an optical photograph of MoS2 in Example 1, and (d) is a magnified micrograph of a portion of Figure (c). Figure 3 This is a TEM image of the MoS2 thin film from Example 1. Detailed Implementation
[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] Example 1 like Figure 1 As shown, a method for preparing a large-area molybdenum disulfide thin film includes the following steps: (1) Weigh 1 mg of sodium chloride (NaCl, AR), take 10 ml of ammonia solution with a concentration of 25 wt%, first add NaCl to the ammonia solution, sonicate for 5 min to dissolve it completely, and obtain mixed solution 1; (2) Weigh 10 mg of molybdenum oxide (MoO3), slowly add the molybdenum oxide to 10 ml of mixed solution 1, sonicate for 20 min to dissolve it completely, and obtain mixed solution 2; (3) Transfer the obtained mixture solution 2 to a quartz boat and dry it in a vacuum drying oven at 60°C for more than 2 hours until the moisture is fully evaporated. A modified molybdenum source coating can then be obtained on the bottom of the quartz boat. (4) The substrate used is SiO2 / Si, where the SiO2 thickness is 300 nm. Before growth, the substrate is cleaned by ultrasonic cleaning with acetone (C3H6O, AR), anhydrous ethanol (C2H6O, AR) and deionized water for 18 min in sequence. Then, the substrate is purged with nitrogen gas gun to remove residual moisture and obtain a clean growth substrate. The SiO2 substrate is placed with the modified molybdenum source coating facing the bottom of the quartz boat, with the substrate and molybdenum source kept 1.9 cm apart, and placed in the high-temperature zone of a dual-temperature zone tube furnace; then, a quartz boat containing high-purity sulfur powder (S, 99.99%) is placed in the low-temperature zone near the gas inlet of the dual-temperature zone tube furnace, and the distance between the two boats is 30 cm. After the internal part of the double-temperature zone tube furnace is pumped to vacuum by a vacuum pump, nitrogen (N2, 99.99%) is introduced to restore the pressure in the tube to normal pressure, and this is repeated three times to remove the influence of air; N2 is used as the carrier gas during the growth process, and a constant flow rate of 90 sccm is maintained; the molybdenum source is gradually heated to 730°C at a rate of 25°C / min, and then maintained at this temperature, during which the influence of ammonia is removed; after the specified temperature of the molybdenum source is reached, the S source is heated to 170°C at a rate of 50°C / min, the growth process lasts for 15 min, and then natural cooling to room temperature is performed to obtain a large-area molybdenum disulfide film.
[0021] Comparative Example 1 This comparative example is basically the same as Example 1, except that in step (2), the ammonia water is replaced with deionized water.
[0022] As can be seen from Figure 2 (a), the MoS2 film obtained without ammonia water pretreatment has a too high nucleation density, and the film distribution is obviously not uniform, with a larger film thickness at the center. Figure 2 As can be seen from (b), it can be seen from the local magnification that the growing film at the boundary is still in a discontinuous state.
[0023] Figure 2 As can be seen from Figure 2 (c), after ammonia water pretreatment, the uniformity of the obtained MoS2 film is obviously improved; as can be seen from (d), local microscopic magnification shows that a uniform and continuous film can still be obtained at the boundary.
[0024] Figure 3 The TEM image of the MoS2 film of Example 1 is shown in Figure 3 (a), and the MoS2 film has very high thickness uniformity and no discontinuous holes appear. Figure 3 (b) is a local magnification of Figure 3 (a), and the lattice spacing is 0.16 nm and 0.27 nm, respectively, corresponding to the (110) and (100) lattice orientations of MoS2, proving that the MoS2 prepared is a high-quality single-crystal film.
[0025] The above merely describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing a large-area molybdenum disulfide thin film, characterized in that, The method comprises the following steps: (1) adding NaCl into an ammonia water solution, mixing uniformly under ultrasonic, to obtain a mixed solution 1; (2) adding MoO3 into the mixed solution 1, mixing uniformly under ultrasonic, to obtain a mixed solution 2; (3) vacuum drying the mixed solution 2, to obtain a modified molybdenum source coating; (4) placing a substrate towards the modified molybdenum source coating, and spacing the substrate and the modified molybdenum source coating, and then placing in a high temperature zone of a double-temperature zone tube furnace, and placing sulfur powder in a low temperature zone of the double-temperature zone tube furnace, to prepare a large-area molybdenum disulfide film by using a CVD method.
2. The method of claim 1, wherein the molybdenum disulfide thin film is formed on a substrate. The method for preparing a large-area molybdenum disulfide film by using a CVD method is as follows: After vacuumizing the double-temperature zone tube furnace, nitrogen is introduced into the furnace until the pressure in the furnace is restored to normal pressure, and the process is repeated for multiple times to eliminate the influence of air; nitrogen is used as a carrier gas, and a constant flow rate of 80-100 sccm is maintained; the modified molybdenum source coating is gradually heated to 720-750°C at a speed of 20-30°C / min, and then maintained at the temperature; after the modified molybdenum source coating reaches the specified temperature, the sulfur powder is heated to 160-180°C at a speed of 45-55°C / min, the growth process lasts for 10-20 min, and then natural cooling to room temperature is performed.
3. A method for preparing a large-area molybdenum disulfide thin film according to claim 1 or 2, characterized in that, The spacing distance between the high temperature zone and the low temperature zone is 25-40 cm.
4. The method of claim 2, wherein the molybdenum disulfide thin film is formed on a substrate. The modified molybdenum source coating is heated to 730°C, and the sulfur powder is heated to 170°C.
5. The method of claim 1, wherein the molybdenum disulfide thin film is formed on a substrate. In step (1), the amount of NaCl is 1 mg, and the amount of the ammonia water solution is 5-20 ml; in step (2), the amount of MoO3 is 10 mg, and the amount of the mixed solution 1 is 5-20 ml.
6. The method of claim 1, wherein the molybdenum disulfide thin film is formed on a substrate having a size of 1 m x 1 m or more. In step (3), the drying temperature of the mixed solution 2 is 50-80°C, until the water is fully volatilized.
7. The method according to claim 6, wherein the molybdenum disulfide thin film is formed on a substrate having a size of 1 m2 or more. In step (3), the drying temperature of the mixed solution 2 is 60°C.
8. The method of claim 1, wherein the molybdenum disulfide thin film is formed on a substrate having a size of 1 m2 or more. In step (4), the spacing between the substrate and the modified molybdenum source coating is 1.5-2.5 cm.
9. The method of claim 1, wherein the molybdenum disulfide thin film is formed on a substrate having a size of 1 m x 1 m or more. In step (4), the substrate is SiO2 / Si, and the SiO2 faces the modified molybdenum source coating.
10. A large-area molybdenum disulfide film prepared by using the preparation method in any one of claims 1-9.