Methods for controlling the surface properties and thickness of multilayer transition metal dichalcogenide thin films

Abstract

This invention relates to a method for controlling the surface properties and thickness of a multilayer transition metal dichalcogenide thin film. After forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film, the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed is treated at least once with an ammonium sulfide aqueous solution, thereby enabling the surface properties and thickness of the transition metal dichalcogenide to be controlled simply and inexpensively without the need for complex equipment for heat treatment, plasma or laser etching, etc.

Description

[Technical Field]

[0001] The present invention relates to a method for controlling the surface properties and thickness of a multilayer transition metal dichalcogenide thin film, and more particularly to a method for controlling the surface properties and thickness of a multilayer transition metal dichalcogenide thin film, which can simply and inexpensively improve the performance of a semiconductor material by forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film, and then treating the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed with an ammonium sulfide aqueous solution at least once. [Background technology]

[0002] Two-dimensional materials have a structure in which strong covalent bonds are formed within a single layer and layers are bound by relatively weak van der Waals forces, making them chemically stable.

[0003] Two-dimensional (2D) transition metal dichalcogenides (TMD) materials, such as molybdenum diselenide (MoSe2), molybdenum disulfide (MoS2), and molybdenum ditelluride (MoTe2), are widely used in next-generation electronic and optoelectronic devices, such as chemical sensors, memory devices, batteries, phototransistors, and photodetectors, due to their excellent physical, electronic, and mechanical properties.

[0004] The structure of a transition metal dichalcogenide is MX2 (M: transition metal, X: chalcogenide), which is a substance in which a transition metal from Groups 4 to 10 and two chalcogen elements are covalently bonded within the same plane. Such transition metal dichalcogenides clearly exhibit the stability and property differences due to the single lattice structure, and exhibit semiconducting properties when the single lattice shape is trigonal prismatic, and metallic properties when it is octahedral.

[0005] Transition metal dichalcogenides possessing the above-described properties have attracted considerable interest in a wide variety of research fields. In particular, solution-processable transition metal dichalcogenides have emerged as a novel class of materials that not only possess metallic properties but also exhibit remarkable electronic and catalytic properties that make them suitable for a wide range of applications in optoelectronic, energy device, and bio-application fields.

[0006] In order to utilize transition metal dichalcogenides in a wide variety of application fields, surface properties and thickness are controlled using heat treatment, plasma and laser etching techniques, etc. However, these methods require complex equipment settings, and therefore there is a need for the development of a simpler and less expensive method for controlling the surface properties and thickness of transition metal dichalcogenides. Summary of the Invention [Problem to be solved by the invention]

[0007] The technical problem to be solved by the present invention is to provide a method for controlling the surface properties and thickness of a multilayer transition metal dichalcogenide thin film, which can simply and inexpensively improve the performance of a semiconductor material by forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film, and then treating the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed with an ammonium sulfide aqueous solution at least once.

[0008] The technical problems of the present invention are not limited to the problems described above, and other problems not mentioned will be apparent to those skilled in the art from the following description. [Means for solving the problem]

[0009] According to one embodiment of the present invention for achieving the above technical object, there is provided a method for controlling surface properties of a multilayer transition metal dichalcogenide thin film, the method comprising the steps of: forming a multilayer transition metal dichalcogenide thin film on a substrate using a transition metal chalcogen compound (S10); forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film (S20); and treating the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed with an ammonium sulfide aqueous solution (S30).

[0010] According to an embodiment of the present invention, in step (S10), the transition metal chalcogen compound may be any one of molybdenum diselenide (MoSe), molybdenum disulfide (MoS), and molybdenum ditelluride (MoTe).

[0011] According to one embodiment of the present invention, the transition metal chalcogen compound may be molybdenum diselenide (MoSe2).

[0012] According to an embodiment of the present invention, in step (S20), the amorphous transition metal oxide thin film may be formed by oxidizing the multilayer transition metal dichalcogenide thin film.

[0013] According to one embodiment of the present invention, the amorphous transition metal oxide thin film may be formed by oxidizing the multilayer transition metal dichalcogenide thin film by an oxygen plasma oxidation method.

[0014] According to an embodiment of the present invention, in the step (S30), the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film is formed may be immersed in the ammonium sulfide aqueous solution.

[0015] According to another embodiment of the present invention for achieving the above technical object, there is provided a method for controlling the thickness of a multilayer transition metal dichalcogenide thin film, including the steps of: forming a multilayer transition metal dichalcogenide thin film on a substrate using a transition metal chalcogen compound (S100); forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film (S200); primarily treating the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed with an ammonium sulfide aqueous solution (S300); and secondarily treating the primarily treated multilayer transition metal dichalcogenide thin film with the ammonium sulfide aqueous solution (S400).

[0016] According to another embodiment of the present invention, in step (S10)0, the transition metal chalcogen compound may be any one of molybdenum diselenide (MoSe2), molybdenum disulfide (MoS2), and molybdenum ditelluride (MoTe2).

[0017] According to another embodiment of the present invention, the transition metal chalcogen compound may be molybdenum diselenide (MoSe2).

[0018] According to another embodiment of the present invention, in step (S200), the amorphous transition metal oxide thin film may be formed by oxidizing the multilayer transition metal dichalcogenide thin film.

[0019] According to another embodiment of the present invention, the amorphous transition metal oxide thin film may be formed by oxidizing the multilayer transition metal dichalcogenide thin film by an oxygen plasma oxidation method.

[0020] According to another embodiment of the present invention, in the step (S300), the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film is formed may be immersed in the ammonium sulfide aqueous solution.

[0021] According to another embodiment of the present invention, in the step (S400), the primarily treated multilayer transition metal dichalcogenide thin film may be immersed in the ammonium sulfide aqueous solution.

[0022] According to another embodiment of the present invention, the second processing time of the step (S400) may be longer than the first processing time of the step (S300). [Effects of the Invention]

[0023] According to the present invention as described above, after forming an amorphous transition metal oxide thin film on a multilayer transition metal dichalcogenide thin film, the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed is treated at least once with an ammonium sulfide aqueous solution, thereby achieving the effect of easily and inexpensively controlling the surface characteristics and thickness of the transition metal dichalcogenide without setting up complex equipment for heat treatment, plasma and laser etching, etc.

[0024] Furthermore, according to the present invention as described above, when a multilayer transition metal dichalcogenide thin film having an amorphous transition metal oxide thin film formed thereon is used as a sensor activation layer for sensing hazardous elements such as hydrogen, it is possible to increase the adsorption area of hazardous elements by controlling the surface flatness of the amorphous transition metal oxide thin film and forming nanostructures, which can be used to control the specific surface area of the sensor activation layer.

[0025] Furthermore, according to the present invention as described above, when the multilayer transition metal dichalcogenide thin film is used as a semiconductor device, it is possible to control the uniform thin film thickness and the number of layers, which has the effect of improving the characteristics of the semiconductor device.

[0026] The effects of the present invention are not limited to those described above, and other effects not mentioned will be apparent to those skilled in the art from the following description. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a flow chart showing a method for controlling the surface properties of a multilayer transition metal dichalcogenide thin film according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram illustrating a method for controlling the surface properties of a multilayer transition metal dichalcogenide thin film according to one embodiment of the present invention. [Figure 3] 4 is a flow chart showing a process for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to another embodiment of the present invention. [Figure 4] 1 is a photograph showing an optical image of Example 1. [Figure 5] 1 is a graph showing an atomic force microscope (AFM) image of Example 1 and a height profile extracted from the AFM image. [Figure 6] 1(a) is a graph showing the Raman spectrum of Example 1, (b) is a graph in which A1g is enlarged, and (c) is a graph in which E1g is enlarged. [Figure 7] 1 is a graph showing an AFM image of Example 2 and a height profile extracted from the AFM image. DETAILED DESCRIPTION OF THE INVENTION

[0028] The advantages and features of the present invention, as well as methods for achieving them, will become more apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below. The present invention can be embodied in various different forms. These embodiments are provided solely to complete the disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art. The present invention is defined solely by the scope of the claims. Therefore, in some embodiments, well-known process steps, well-known device structures, and well-known techniques are not specifically described to avoid obscuring the present invention. Throughout the specification, the same reference numerals refer to the same elements.

[0029] The terms used in this specification are merely used to describe the embodiments and are not intended to limit the present invention. In this specification, singular expressions include plural expressions unless the context clearly dictates otherwise. As used in this specification, terms such as "comprises" and / or "comprising" only specify the presence of the referenced components, steps, operations and / or elements, and do not preclude the possibility of the presence or addition of one or more other components, steps, operations and / or elements.

[0030] The identification numbers used in each step are for ease of description and do not dictate the order of the steps, and the steps may be performed in a different order than specified unless the context clearly dictates a particular order, i.e., the steps may be performed in the same order as specified, or may be performed substantially simultaneously, or may be performed in the reverse order.

[0031] Unless otherwise specified herein or clearly contradicted by the context, all terms used in this disclosure, including technical and scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention belongs. In addition, commonly used terms, such as those defined in dictionaries, are not to be construed as idealized or overly formal meanings unless expressly defined in this application.

[0032] According to a preferred embodiment of the present invention, there is provided a method for controlling the surface properties of a multilayer transition metal dichalcogenide thin film, comprising the steps of: forming a multilayer transition metal dichalcogenide thin film on a substrate using a transition metal chalcogen compound (S10); forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film (S20); and treating the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed with an ammonium sulfide aqueous solution (S30).

[0033] The method for controlling the surface properties of a multilayer transition metal dichalcogenide thin film according to the present invention will be described in detail below with reference to the process flow diagram of FIG. 1 and the schematic diagram of FIG.

[0034] First, a multilayer transition metal dichalcogenide thin film is formed on a substrate using a transition metal chalcogen compound (S10).

[0035] Transition metal chalcogen compounds are two-dimensional materials that can replace graphene. In principle, they only interact with the constituent atoms in two dimensions. Therefore, in transition metal chalcogen compounds, carrier transport is ballistic, which is completely different from that in conventional thin films or bulk materials. This makes it possible to achieve high mobility, high speed, and low power consumption.

[0036] The transition metal chalcogen compound may be any one of molybdenum diselenide (MoSe2), molybdenum disulfide (MoS2), and molybdenum ditelluride (MoTe2), and is preferably molybdenum diselenide (MoSe2). However, the transition metal is not limited thereto, and the transition metal of the transition metal chalcogen compound may be replaced with tungsten (W), tin (Sn), rhenium (Re), tantalum (Ta), titanium (Ti), etc., as long as it can form a 2H crystal structure with volatile chalcogen.

[0037] According to one embodiment of the present invention, a method for forming a multilayer transition metal dichalcogenide thin film on a substrate using a transition metal chalcogen compound can be a variety of methods, including, but not limited to, a scotch tape peeling method, chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), and a solution process.

[0038] The substrate may be a silicon (Si) substrate, but is not limited to this, and a wide variety of substrates such as a ceramic substrate can be used.

[0039] Next, an amorphous transition metal oxide thin film is formed on the multilayer transition metal dichalcogenide thin film (S20).

[0040] Amorphous refers to a solid substance that has a uniform composition but does not have a regular lattice structure because the atomic arrangement is disordered like that of a liquid.

[0041] According to an embodiment of the present invention, an amorphous transition metal oxide thin film can be formed by oxidizing a multilayer transition metal dichalcogenide thin film. The method for oxidizing the multilayer transition metal dichalcogenide thin film is preferably an oxygen plasma method, because it allows for control of the process rate and the formation of a uniform oxide. However, the method is not limited thereto, and various oxidation methods, such as dry thermal oxidation, wet thermal oxidation, and electrochemical oxidation, can also be used.

[0042] According to one embodiment of the present invention, the diffusion distance of oxygen atoms accelerated during oxygen plasma treatment within a transition metal chalcogen compound crystal is within 3 nm, so that the surface of the top layer of the multilayer transition metal dichalcogenide thin film is oxidized, thereby forming a heterojunction structure between the amorphous transition metal oxide thin film and the multilayer transition metal dichalcogenide thin film.

[0043] For example, when the transition metal chalcogenide is molybdenum diselenide (MoSe2), the surface of the top layer of the multilayered molybdenum diselenide (MoSe2) thin film is oxidized to form a molybdenum oxide film (MoO x ) thin film and multilayer molybdenum diselenide (MoSe2) thin film. x / MoSe2 heterojunction structure is formed.

[0044] Finally, the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed is treated with an aqueous solution of ammonium sulfide ((NH4)2S) (S30).

[0045] According to one embodiment of the present invention, the method of treating the multilayer transition metal dichalcogenide thin film having an amorphous transition metal oxide thin film formed thereon with an ammonium sulfide ((NH4)2S) aqueous solution is preferably a method of immersing the multilayer transition metal dichalcogenide thin film having an amorphous transition metal oxide thin film formed thereon in the ammonium sulfide ((NH4)2S) aqueous solution. However, the method is not limited thereto, and methods such as spray injection can also be used as long as process conditions are met that can provide a sufficient reduction reaction in a uniform temperature environment.

[0046] When a multilayer transition metal dichalcogenide thin film on which an amorphous transition metal oxide thin film has been formed is immersed in an ammonium sulfide ((NH4)2S) aqueous solution, a reduction reaction occurs between the ammonium sulfide ((NH4)2S) and the amorphous transition metal oxide thin film, which can impart roughness to the surface of the multilayer transition metal dichalcogenide thin film. When the surface roughness of the multilayer transition metal dichalcogenide thin film changes, the mobility of charges moving on the semiconductor surface and the rate of increase in current due to scattering at the surface change, and through this, the surface characteristics of the multilayer transition metal dichalcogenide thin film can be easily and inexpensively controlled.

[0047] According to one embodiment of the present invention, the degree of surface roughness can be controlled by adjusting the time for which a multilayer transition metal dichalcogenide thin film, on which an amorphous transition metal oxide thin film has been formed, is immersed in an ammonium sulfide ((NH4)2S) aqueous solution. The immersion time for controlling the degree of surface roughness is preferably 1 to 600 seconds; an immersion time shorter than 1 second is insufficient to achieve the initial reduction reaction, while an immersion time longer than 600 seconds may result in etching of the entire amorphous transition metal oxide thin film.

[0048] According to a preferred embodiment of the present invention, there is provided a method for controlling the thickness of a multilayer transition metal dichalcogenide thin film, including the steps of: forming a multilayer transition metal dichalcogenide thin film on a substrate using a transition metal chalcogen compound (S100); forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film (S200); subjecting the multilayer transition metal dichalcogenide thin film having the amorphous transition metal oxide thin film formed thereon to a first treatment with an ammonium sulfide aqueous solution (S300); and subjecting the first-treated multilayer transition metal dichalcogenide thin film to a second treatment with the ammonium sulfide aqueous solution (S400).

[0049] The method for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to the present invention will be described in detail below with reference to the process flow diagram of FIG.

[0050] First, a multilayer transition metal dichalcogenide thin film is formed on a substrate using a transition metal chalcogen compound (S100).

[0051] The type of transition metal chalcogen compound and substrate, and the method of forming a multilayer transition metal dichalcogenide thin film on a substrate using a transition metal chalcogen compound are similar to step (S10) of the method of controlling the surface properties of a multilayer transition metal dichalcogenide thin film, and therefore, detailed description thereof will be omitted for the sake of brevity.

[0052] Next, an amorphous transition metal oxide thin film is formed on the multilayer transition metal dichalcogenide thin film (S200).

[0053] The method for forming an amorphous transition metal oxide thin film and the formation of a heterojunction structure between an amorphous transition metal oxide thin film and a multilayer transition metal dichalcogenide thin film are similar to step S20 of the method for controlling the surface properties of a multilayer transition metal dichalcogenide thin film, and therefore, detailed description thereof will be omitted for the sake of brevity.

[0054] Next, the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed is subjected to a primary treatment using an ammonium sulfide aqueous solution (S300), and finally, the primary-treated multilayer transition metal dichalcogenide thin film is subjected to a secondary treatment using an ammonium sulfide aqueous solution (S400).

[0055] According to another embodiment of the present invention, a step (S300) of first treating a multilayer transition metal dichalcogenide thin film having an amorphous transition metal oxide thin film formed thereon with an ammonium sulfide aqueous solution and a step (S400) of secondly treating the first-treated multilayer transition metal dichalcogenide thin film with an ammonium sulfide aqueous solution may be performed sequentially, and it is preferable that the second-treatment step (S400) is performed for a longer time than the first-treatment step (S300). However, the present invention is not limited thereto, and the first-treated multilayer transition metal dichalcogenide thin film may be subjected to a step of washing before being second-treated with an ammonium sulfide aqueous solution.

[0056] According to another embodiment of the present invention, the method of subjecting a multilayer transition metal dichalcogenide thin film having an amorphous transition metal oxide thin film formed thereon to a primary treatment with an ammonium sulfide ((NH4)2S) aqueous solution and the method of subjecting the primary-treated multilayer transition metal dichalcogenide thin film to a secondary treatment with an ammonium sulfide ((NH4)2S) aqueous solution are preferably methods of immersing the thin film in an ammonium sulfide ((NH4)2S) aqueous solution.

[0057] When a multilayer transition metal dichalcogenide thin film having an amorphous transition metal oxide thin film formed thereon is first immersed in an ammonium sulfide aqueous solution, a reduction reaction occurs between the ammonium sulfide and the amorphous transition metal oxide thin film, and some or all of the amorphous transition metal oxide thin film is removed depending on the time of the first immersion. Then, when the multilayer transition metal dichalcogenide thin film is secondarily immersed in an ammonium sulfide aqueous solution, the thickness of the multilayer transition metal dichalcogenide thin film decreases, and the thickness of the multilayer transition metal dichalcogenide thin film can be adjusted depending on the time of the second immersion.

[0058] During the first immersion in an ammonium sulfide aqueous solution, some of the oxygen atoms penetrate into the transition metal dichalcogenide thin film during the process of removing part or all of the amorphous transition metal oxide thin film. Then, during the second immersion in an ammonium sulfide aqueous solution, the oxygen atoms that have penetrated into the transition metal dichalcogenide thin film react with the ammonium sulfide aqueous solution, causing additional decomposition of the surrounding transition metal dichalcogenide. Consequently, the thickness of the transition metal dichalcogenide thin film through which the oxygen atoms have penetrated decreases, and the thickness of the multilayer transition metal dichalcogenide thin film can be adjusted by adjusting the time of the second immersion in ammonium sulfide.

[0059] Hereinafter, an embodiment of the method for controlling the surface properties and thickness of a multilayer transition metal dichalcogenide thin film of the present invention will be described. However, this is merely one of the best modes of the present invention and does not represent the entire technical concept of the present invention. Therefore, it should be understood that there may be various equivalents and modifications that can be substituted for these at the time of filing this application.

[0060] Example 1: Controlling the surface properties of multilayer transition metal dichalcogenide thin films 1-1. Fabrication of multilayer molybdenum diselenide (MoSe2) thin films Multilayer molybdenum diselenide (MoSe2) thin films were formed on a silicon oxide (SiO2) substrate with a thickness of 300 nm by thermally growing it on a P-type silicon (Si) substrate using a scotch tape method.

[0061] 1-2. Oxygen plasma treatment of multilayer molybdenum diselenide (MoSe2) thin films The multilayer molybdenum diselenide (MoSe) thin film formed on the silicon oxide (SiO) substrate was treated with oxygen plasma for about 20 minutes using a plasma generator (PDC-32G-2, manufactured by Harrick Plasma, Inc.) under the conditions of 10.5 W (power), 2.33 torr (chamber pressure), and oxygen flow rate (60 sccm). Through this treatment, an amorphous molybdenum oxide (MoO) film was formed on the multilayer molybdenum diselenide (MoSe) thin film. x ) was formed.

[0062] 1-3. Immersion in ammonium sulfide ((NH4)2S) aqueous solution Amorphous molybdenum oxide film (MoO x The multilayered molybdenum diselenide (MoSe2) thin film on which the SiO2 film was formed was immersed in an ammonium sulfide ((NH4)2S) aqueous solution (concentration: 25%) at 323K for approximately 10 seconds.

[0063] 1-4.Measurement results Optical images, AFM images, height profiles extracted from the AFM images, and Raman spectra of pristine multilayer molybdenum diselenide (MoSe2) thin films, multilayer MoSe2 thin films after oxygen plasma treatment, and multilayer MoSe2 thin films after immersion treatment in an ammonium sulfide aqueous solution were measured and compared.

[0064] Referring to FIG. 4, it can be seen that the initial shape of the multilayered molybdenum diselenide (MoSe) thin film is maintained even after oxidation by oxygen plasma treatment and reduction by immersion in an ammonium sulfide aqueous solution, and partial oxidation and reduction are induced in the top layer of the multilayered molybdenum diselenide (MoSe) thin film.

[0065] Referring to FIG. 5, the initial multilayered molybdenum diselenide (MoSe) thin film does not show any significant topographical changes (FIG. 5(a) and FIG. 5(b)). After oxygen plasma treatment, the multilayered molybdenum diselenide (MoSe) thin film becomes amorphous molybdenum oxide (MoO) film on the top layer. x The multilayered molybdenum diselenide (MoSe) thin films exhibit particle features with various diameters (0.12 nm to 0.89 nm) and heights (1 nm to 60 nm), consistent with the development of nanostructures (Figures 5(c) and 5(d)). Furthermore, after immersion in an ammonium sulfide aqueous solution, the multilayered MoSe thin films exhibit changes in surface properties, including the formation of nanostructures on the surface, with particles of sizes less than 5 nm uniformly distributed (Figures 5(e) and 5(f)).

[0066] Referring to FIG. 6, the A of the initial multilayer molybdenum diselenide (MoSe2) thin film 1g Peak: 239.1cm -1 6(a) and 6(b)), and the A of multilayer molybdenum diselenide (MoSe2) thin films after oxygen plasma treatment. 1g Peak: 241.8cm -1 Move to 240cm -1 The peak intensity decreases by about 70% near the SiO2 peak, and the molybdenum diselenide (MoSe2) film with a thickness of a few nanometers is transformed into an amorphous molybdenum oxide (MoO x ) (Fig. 6(a) and 6(b)). After immersion in an ammonium sulfide solution, the A 1g The peak intensity increases after oxygen plasma treatment compared to the multilayer molybdenum diselenide (MoSe2) thin film, but the A 1g It can be seen that the peak position remained constant while the surface properties changed (Figures 6(a) and 6(b)).

[0067] E of the initial multilayer molybdenum diselenide (MoSe2) thin film, the multilayer molybdenum diselenide (MoSe2) thin film after oxygen plasma treatment, and the multilayer molybdenum diselenide (MoSe2) thin film after immersion treatment in an ammonium sulfide aqueous solution. 1g It can be seen that the peaks do not change regardless of the oxidation and reduction reactions (Fig. 6(c)). In addition, the A of the multilayer molybdenum diselenide (MoSe2) thin film after ammonium sulfide treatment 1g Peak vs. E 1g Peak distance is approximately 74.2 cm -1 and the initial multilayer molybdenum diselenide (MoSe2) thin film A 1g Peak vs. E 1g The peak distances are almost the same as those of the initial multilayered molybdenum diselenide (MoSe2) thin film. This indicates that the oxygen plasma treatment oxidizes only the top layer of the initial multilayered molybdenum diselenide (MoSe2) thin film, and the molybdenum diselenide (MoSe2) thin film becomes a molybdenum oxide (MoO x ) (Figure 6(c)).

[0068] Example 2: Thickness control of multilayer transition metal dichalcogenide thin films 2-1. Fabrication of multilayer molybdenum diselenide (MoSe2) thin films Multilayer molybdenum diselenide (MoSe2) thin films were formed on a silicon oxide (SiO2) substrate with a thickness of 300 nm by thermally growing it on a P-type silicon (Si) substrate using a scotch tape method.

[0069] 2-2. Oxygen plasma treatment of multilayer molybdenum diselenide (MoSe2) thin films The multilayer molybdenum diselenide (MoSe) thin film formed on the silicon oxide (SiO) substrate was treated with oxygen plasma for about 20 minutes using a plasma generator (PDC-32G-2, manufactured by Harrick Plasma, Inc.) under the conditions of 10.5 W (power), 2.33 torr (chamber pressure), and oxygen flow rate (60 sccm). Through this treatment, an amorphous molybdenum oxide (MoO) film was formed on the multilayer molybdenum diselenide (MoSe) thin film. x ) was formed.

[0070] 2-3. First immersion in ammonium sulfide ((NH4)2S) aqueous solution A multilayer molybdenum diselenide (MoSe2) thin film on which an amorphous molybdenum oxide (MoOx) film was formed was immersed in an aqueous ammonium sulfide ((NH4)2S) solution (concentration: 25%) at 323K for approximately 30 minutes.

[0071] 2-4. Secondary immersion in ammonium sulfide ((NH4)2S) aqueous solution The multilayered molybdenum diselenide (MoSe2) thin film that had undergone the first immersion treatment was immersed in an aqueous solution of ammonium sulfide ((NH4)2S) (concentration: 25%) at 323K for approximately 1 hour.

[0072] 2-5.Measurement results AFM images, height profiles extracted from the AFM images, and surface roughness (RMS) of the initial multilayer molybdenum diselenide (MoSe2) thin film, the multilayer molybdenum diselenide (MoSe2) thin film after oxygen plasma treatment, the multilayer molybdenum diselenide (MoSe2) thin film after the first immersion treatment in an ammonium sulfide aqueous solution, and the multilayer molybdenum diselenide (MoSe2) thin film after the second immersion treatment in an ammonium sulfide aqueous solution were measured and compared.

[0073] Referring to FIG. 7, the initial thickness of the multilayered molybdenum diselenide (MoSe2) thin film was about 88.4 nm, but after the oxygen plasma treatment, the thickness of the multilayered molybdenum diselenide (MoSe2) thin film increased to about 92.2 nm, and an amorphous molybdenum oxide (MoO2) film with a thickness of about 3.8 nm was formed. x) was formed (Figures 7(a) to 7(d)). After the first immersion in the ammonium sulfide aqueous solution, the thickness of the multilayer molybdenum diselenide (MoSe2) thin film decreased to approximately 86.3 nm, indicating that the amorphous molybdenum oxide (MoOx) film was completely removed. After the second immersion in the ammonium sulfide aqueous solution, the thickness of the multilayer molybdenum diselenide (MoSe2) thin film rapidly decreased to approximately 38.9 nm, indicating that the thickness of the multilayer molybdenum diselenide (MoSe2) thin film can be adjusted by changing the second immersion time in the ammonium sulfide aqueous solution (Figures 7(e) to 7(h)).

[0074] The above-described embodiments of the present invention are merely illustrative, and the scope of protection of the present invention encompasses a wide variety of modifications and equivalents that can be made by a person skilled in the art of the present invention.

Claims

1. forming a multilayer transition metal dichalcogenide thin film on a substrate using a transition metal chalcogen compound (S10); forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film (S20); a step (S30) of treating the multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed with an ammonium sulfide aqueous solution; Contains A method for controlling the surface properties of a multilayer transition metal dichalcogenide thin film, comprising:

2. In the step (S10), The transition metal chalcogen compound is molybdenum diselenide (MoSe ２ ), molybdenum disulfide (MoS ２ ) and molybdenum ditelluride (MoTe ２ ) is one of the following A method for controlling the surface properties of the multilayer transition metal dichalcogenide thin film according to claim 1.

3. The transition metal chalcogen compound is molybdenum diselenide (MoSe ２ ) 3. A method for controlling the surface properties of the multilayer transition metal dichalcogenide thin film according to claim 2.

4. In the step (S20), The amorphous transition metal oxide thin film is formed by oxidizing the multilayer transition metal dichalcogenide thin film. A method for controlling the surface properties of the multilayer transition metal dichalcogenide thin film according to claim 1.

5. The amorphous transition metal oxide thin film is formed by oxidizing the multilayer transition metal dichalcogenide thin film by an oxygen plasma oxidation method.

5. A method for controlling the surface properties of the multilayer transition metal dichalcogenide thin film according to claim 4.

6. In the step (S30), The multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film is formed is immersed in the ammonium sulfide aqueous solution. A method for controlling the surface properties of the multilayer transition metal dichalcogenide thin film according to claim 1.

7. forming a multilayer transition metal dichalcogenide thin film on a substrate using a transition metal chalcogen compound (S100); forming an amorphous transition metal oxide thin film on the multilayer transition metal dichalcogenide thin film (S200); a step (S300) of first treating the multi-layer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film has been formed with an ammonium sulfide aqueous solution; a step (S400) of subjecting the first-treated multilayer transition metal dichalcogenide thin film to a second treatment using the ammonium sulfide aqueous solution; Contains A method for controlling the thickness of a multilayer transition metal dichalcogenide thin film.

8. In the step (S100), The transition metal chalcogen compound is molybdenum diselenide (MoSe ２ ), molybdenum disulfide (MoS ２ ) and molybdenum ditelluride (MoTe ２ ) is one of the following 8. The method for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to claim 7.

9. The transition metal chalcogen compound is molybdenum diselenide (MoSe ２ ) 9. The method for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to claim 8.

10. In the step (S200), The amorphous transition metal oxide thin film is formed by oxidizing the multilayer transition metal dichalcogenide thin film.

8. The method for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to claim 7.

11. The amorphous transition metal oxide thin film is formed by oxidizing the multilayer transition metal dichalcogenide thin film by an oxygen plasma oxidation method. The method for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to claim 10.

12. In the step (S300), The multilayer transition metal dichalcogenide thin film on which the amorphous transition metal oxide thin film is formed is immersed in the ammonium sulfide aqueous solution.

8. The method for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to claim 7.

13. In the step (S400), The first-treated multilayer transition metal dichalcogenide thin film is immersed in the ammonium sulfide aqueous solution.

8. The method for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to claim 7.

14. The secondary processing time of the step (S400) is longer than the primary processing time of the step (S300).

8. The method for controlling the thickness of a multilayer transition metal dichalcogenide thin film according to claim 7.

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