KR20220126076A - Method for manufacturing transition metal dichalcogenide - Google Patents

Abstract

The present invention relates to a method for manufacturing a transition metal chalcogen compound capable of synthesizing a transition metal chalcogen compound having excellent crystallinity quickly and in a large area. The present invention includes the steps of: forming a graphene thin film; and forming a transition metal chalcogen compound thin film.

Description

Method for producing a transition metal chalcogen compound {METHOD FOR MANUFACTURING TRANSITION METAL DICHALCOGENIDE}

The present invention relates to a method for preparing a transition metal chalcogen compound.

Among the elements belonging to group 16 of the periodic table, the five elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and polonium (Po) are called oxygen group elements, and among them, sulfur, selenium, Only the three elements of tellurium are called sulphur or chalcogens.

Oxygen and sulfur are representative non-metal elements, but with the increase of atomic number, non-metallic properties are lost and metallic properties are increased. Selenium, tellurium, and polonium are rare elements, and polonium is a naturally radioactive element.

Metal chacogenide is a compound of a transition metal and a chalcogen, and is a nanomaterial having a structure similar to graphene. Since its thickness is very thin with a thickness of several atomic layers, it has flexible and transparent properties, and exhibits various properties such as semiconductors and conductors electrically.

In particular, the metal chalcogenide of semiconductor nature has an appropriate band gap and exhibits an electron mobility of several hundred cm2/V·s, so it is suitable for the application of semiconductor devices such as transistors, and is suitable for use in flexible transistor devices in the future. It has potential.

A method for preparing such a metal chalcogenide nano-thin film has been actively studied in recent years. In order to apply such a metal chalcogenide thin film as the above device, for example, a method for synthesizing a thin film uniformly and continuously over a large area has been studied. In particular, there is a need for a technology capable of rapidly synthesizing a metal chalcogenide thin film over a large area and improving the crystallinity of the metal chalcogenide.

The technical problem to be achieved by the present invention is to provide a manufacturing method capable of synthesizing a transition metal chalcogen compound with improved crystallinity quickly and over a large area.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

One embodiment of the present invention comprises the steps of forming a graphene thin film including two or more graphene layers on a substrate; And by using atomic layer deposition to form a transition metal chalcogen compound from the transition metal precursor and the chalcogen precursor on the graphene thin film, forming a transition metal chalcogen compound thin film; transition metal chalcogen compound comprising a A manufacturing method is provided.

The method for preparing a transition metal chalcogen compound according to an exemplary embodiment of the present invention can effectively synthesize a transition metal chalcogen compound having excellent crystallinity.

In addition, the method for preparing a transition metal chalcogen compound according to an exemplary embodiment of the present invention can be synthesized in a large area at a rapid rate of the transition metal chalcogen compound.

However, the effects of the present invention are not limited to the above-described effects, and may be variously expanded without departing from the spirit and scope of the present invention.

1 is a view schematically showing a method for preparing a transition metal chalcogen compound according to an embodiment of the present invention.
Figure 2 is a view schematically showing the form of the transition metal chalcogen compound layer according to an embodiment of the present invention.
Figure 3 is a view schematically showing a method for preparing a transition metal chalcogen compound on the oxidized graphene layer according to an embodiment of the present invention.
4 is a view showing an image of the transition metal chalcogen compound thin film prepared in Example 1 of the present invention.
5 is a view showing an image of one CuSe nanoplate observed in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention.
6 is a view showing an image of observing two CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention.
7 is a view showing an image of another CuSe nanoplate included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention.
8 is a view showing an image of observing two CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention.
9 is a view showing an image of observing a plurality of CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention.
10 is a scanning transmission electron microscope (STEM) image and energy dispersive X-ray spectroscopy (EDS) analysis image of a plurality of CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. to be.
11 is a view showing STEM images and EDS analysis images of a plurality of CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention.
12 is a graph showing the results of XPS (x-ray photoelectron spectroscopic analysis) of the transition metal chalcogen compound thin film prepared in Example 1 of the present invention.
13 is a view showing an image of the transition metal chalcogen compound thin film prepared in Example 2.
14 is a view showing a topography image of the transition metal chalcogen compound thin film prepared in Examples 1 and 2 of the present invention and the height profile of the synthesized CuSe.
15 is a view showing the Raman spectrum analysis results of the transition metal chalcogen compound thin film prepared in Comparative Example 1, Example 1 and Example 3 of the present invention.
Figure 16 is a view showing an image of the observation of the transition metal chalcogen compound thin film prepared in Comparative Examples 1 and 4 of the present invention.
17 is a view showing a DFT (density functional theory) calculated value of absorbed energy when CuSe is synthesized in the graphene layer of the first layer and the graphene layer of the second layer.

Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

Throughout this specification, when a member is said to be located “on” another member, this includes not only a case in which a member is in contact with another member but also a case in which another member is present between the two members.

In this specification, the terms "step to" and "step to" do not mean "step for".

In the present specification, the term "graphene layer" refers to a graphene in which a plurality of carbon atoms are covalently connected to each other to form a polycyclic aromatic molecule to form a film or sheet, and the carbon atoms connected by covalent bonds These form a 6-membered ring as a basic repeating unit, but it is also possible to further include a 5-membered ring and/or a 7-membered ring. Thus, the "graphene layer" appears as a single layer of carbon atoms covalently bonded to each other (typically sp ² bonds). The "graphene layer" may have various structures, and such a structure may vary depending on the content of 5-membered rings and/or 7-membered rings that may be included in graphene.

Hereinafter, specific details for carrying out the present invention will be described in detail with reference to the accompanying drawings.

One embodiment of the present invention comprises the steps of forming a graphene thin film including two or more graphene layers on a substrate; And by using atomic layer deposition to form a transition metal chalcogen compound from the transition metal precursor and the chalcogen precursor on the graphene thin film, forming a transition metal chalcogen compound thin film; transition metal chalcogen compound comprising a A manufacturing method is provided.

The method for preparing a transition metal chalcogen compound according to an exemplary embodiment of the present invention can effectively synthesize a transition metal chalcogen compound having excellent crystallinity. In addition, the method for preparing a transition metal chalcogen compound according to an exemplary embodiment of the present invention can be synthesized in a large area at a rapid rate of the transition metal chalcogen compound.

According to an exemplary embodiment of the present invention, the graphene thin film may be formed on the substrate by chemical vapor deposition (CVD). By using the chemical vapor deposition method, it is possible to form a high-quality graphene thin film on the substrate over a large area. Further, it is possible to form a graphene thin film on the substrate in a large area, it is possible to easily form the transition metal chalcogen compound thin film on the graphene thin film in a large area.

According to an exemplary embodiment of the present invention, the substrate is silicon, silicon oxide, aluminum oxide, magnesium oxide, silicon carbide, silicon nitride, glass, quartz, sapphire, graphite, polyimide copolymer, polyimide, polyethylene naphthalate (PEN) , fluoropolymer (FEP), and at least one of polyethylene terephthalate (PET), but the type of the substrate is not limited thereto.

According to an exemplary embodiment of the present invention, a graphene thin film is formed on a catalyst layer using a chemical vapor deposition method, and the graphene thin film provided on the catalyst layer is transferred onto the substrate, and two or more graphene films are formed on the substrate. A graphene thin film including a pinned layer may be formed. For example, by supplying hydrogen gas and a carbonization source on the heated catalyst layer, graphene may be synthesized on the catalyst layer. The carbonization source may include at least one of carbon monoxide, carbon dioxide, methane, ethane, ethylene, ethanol, acetylene, propane, butane, butadiene, pentane, pentene, cyclopentadiene, hexane, cyclohexane, benzene, and toluene, The type of the carbonization source is not limited.

According to an exemplary embodiment of the present invention, the catalyst layer is Cu, Ni, Co, Fe, Pt, Au, Al, Cr, Mg, Mn, Rh, Si, Ta, Ti, W, U, V, Zr, Fe, Ge, brass, bronze, and may include at least one of stainless steel. The catalyst layer may be a metal catalyst layer for graphene synthesis, and an appropriate catalyst layer may be selected in consideration of graphene synthesis conditions.

According to an exemplary embodiment of the present invention, the catalyst layer may be provided as a thin film or a thick film. Specifically, the thickness of the catalyst layer may be 1 nm or more and 1,000 nm or less, 1 nm or more and 500 nm or less, or 1 nm or more and 300 nm or less. In addition, the thickness of the catalyst layer may be 1 μm or more and 1,000 μm or less, 1 μm or more and 500 μm or less, 1 μm or more and 100 μm or less, or 1 μm or more and 50 μm or less. In addition, the thickness of the catalyst layer may be 1 mm or more and 5 mm or less. However, the thickness of the catalyst layer is not limited, and the thickness of the catalyst layer may be set in consideration of the synthesis conditions of the graphene layer, the purpose of use of the graphene layer, and the like.

According to an exemplary embodiment of the present invention, the chemical vapor deposition method may be performed at a temperature of 700 °C or higher. Specifically, the chemical vapor deposition method may be performed at a temperature of 750 °C or higher, a temperature of 800 °C or higher, a temperature of 850 °C or higher, a temperature of 900 °C or higher, or a temperature of 1,000 °C or higher. In addition, the chemical vapor deposition method is a temperature of 2,000 ℃ or less, a temperature of 1,900 ℃ or less, a temperature of 1,800 ℃ or less, a temperature of 1,700 ℃ or less, a temperature of 1,600 ℃ or less, or 1,500 ℃ or less It can be performed at a temperature. The temperature at which the chemical vapor deposition method is performed may be set according to the type of material forming the catalyst layer. Specifically, it may be set in consideration of the melting point of the material forming the catalyst layer. For example, when the catalyst layer is formed using copper, the chemical vapor deposition method may be performed at a temperature of 1,000 °C or more and 1,085 °C or less. In addition, when the catalyst layer is formed using nickel, the chemical vapor deposition method may be performed at a temperature of 750° C. or more and 850° C. or less. In addition, when the catalyst layer is formed using palladium, the chemical vapor deposition method may be performed at a temperature of 950°C or higher and 1050°C or lower.

When the temperature at which the chemical vapor deposition method is performed is within the aforementioned range, the graphene layer may be stably formed on the catalyst layer, and the synthesized graphene may have excellent crystallinity. That is, by setting the temperature at which the chemical vapor deposition method is performed in consideration of the melting point of the material used to form the catalyst layer, the graphene layer can be stably formed on the catalyst layer, and the graphene to be synthesized Crystallinity can be further improved.

Meanwhile, as a method of forming the graphene thin film on the substrate, a roll-to-roll process may be used. For example, the method of manufacturing graphene using the roll-to-roll process may use the method described in Korean Patent Registration No. 10-1300799. However, the method for manufacturing graphene using the roll-to-roll process is not limited, and the graphene may be manufactured through the roll-to-roll process used in the art.

According to an exemplary embodiment of the present invention, the graphene thin film provided on the substrate includes two or more graphene layers. In contrast to the case of forming the transition metal chalcogen compound on the graphene layer of one layer, the present inventors have found that when the transition metal chalcogen compound is formed on the graphene thin film including two or more graphene layers, the transition synthesized It was confirmed as described below that the metal chalcogen compound has high crystallinity, and can synthesize a transition metal chalcogen compound thin film having a thicker thickness. That is, the method for producing a transition metal chalcogen compound according to an exemplary embodiment of the present invention can easily synthesize a transition metal chalcogen compound having improved crystallinity on a graphene thin film including two or more graphene layers.

According to an exemplary embodiment of the present invention, the graphene thin film may include 2 or more and 10 or less graphene layers. Specifically, the number of graphene layers included in the graphene thin film may be 2 or more and 8 or less, 2 or more and 6 or less, 2 or more and 4 or less, and 2 or more and 3 or less, and more specifically, the graphene thin film has two layers. It may be made of a graphene layer. When the number of the graphene layers included in the graphene thin film is within the aforementioned range, it is possible to stably and effectively form a transition metal chalcogen compound having excellent crystallinity on the graphene thin film.

According to an exemplary embodiment of the present invention, the upper graphene layer may be provided on all or part of one surface of the lower graphene layer. Based on the substrate, a layer adjacent to the substrate may mean a lower layer, and a layer further apart from the substrate compared to the lower layer may mean an upper layer. For example, a first graphene layer may be provided on one surface of the substrate, and a second graphene layer may be provided on the first graphene layer.

When the first graphene layer is provided on the entire surface of the substrate, the second graphene layer may be provided on all or part of the first graphene layer. That is, the second graphene layer may be provided in the form of an island on one surface of the first graphene layer. In addition, the third graphene layer may be provided on all or part of one surface of the second graphene layer. By adjusting the area of the upper graphene layer provided on one surface of the lower graphene layer, a transition metal chalcogen compound thin film having a thickness gradient may be easily formed as will be described later.

According to an exemplary embodiment of the present invention, the thickness of the graphene thin film may be 0.3 nm or more and 5 nm or less. When the thickness of the graphene thin film is within the aforementioned range, it is possible to stably and effectively form a transition metal chalcogen compound having excellent crystallinity on the graphene thin film. The thickness of the graphene thin film may be controlled by adjusting the number of graphene layers included in the graphene thin film.

1 is a view schematically showing a method for preparing a transition metal chalcogen compound according to an embodiment of the present invention. Specifically, FIG. 1 is a view showing a process of forming a transition metal chalcogen compound using atomic layer deposition (ALD) on a graphene thin film including two or more graphene layers. 1 shows an embodiment using copper (Cu) as a transition metal and selenium (Se) as a chalcogen compound, but limiting the types of transition metals and chalcogen compounds according to an exemplary embodiment in the present invention it is not

According to an exemplary embodiment of the present invention, a transition metal chalcogen compound can be synthesized by using atomic layer deposition on the graphene thin film provided on one surface of the substrate. In particular, the method for producing the transition metal chalcogen compound is by using the graphene thin film including two or more graphene layers as a substrate, even when using an atomic layer deposition method to further improve the growth rate of the transition metal chalcogen compound. and can effectively improve the crystallinity of the synthesized transition metal chalcogen compound.

According to an exemplary embodiment of the present invention, in order to form the transition metal chalcogen compound on the graphene thin film, an atomic layer deposition process used in the art may be used. The temperature at which the atomic layer deposition process is performed may be, for example, 500 °C or less, and specifically, 150 °C or more and 500 °C or less. When the temperature at which the atomic layer deposition process is performed is within the aforementioned range, the transition metal chalcogen compound can be stably synthesized on the graphene thin film.

On the other hand, the temperature at which the atomic layer deposition process is performed may be adjusted according to the types of the transition metal and the chalcogen compound. For example, when copper is used as the transition metal and selenium is used as the chalcogen compound, the temperature at which the atomic layer deposition process is performed may be adjusted to a temperature of 160° C. or more and 190° C. or less.

According to an exemplary embodiment of the present invention, the atomic layer deposition process may be performed in the following way. The inside of the process chamber may be formed in a vacuum state, and the transition metal precursor and the chalcogen precursor may be sequentially supplied into the process chamber. Thereafter, by maintaining the temperature inside the process chamber in the above-described temperature range, the transition metal precursor and the chalcogen precursor react on the surface of the graphene thin film to form a transition metal chalcogen compound. At this time, as described above, the graphene thin film includes two or more graphene layers, so that the transition metal precursor and the chalcogen precursor can be effectively adsorbed to the surface of the graphene thin film, thereby forming a transition metal chalcogen compound. can be easily synthesized.

Thereafter, the transition metal precursor and the chalcogen precursor remaining in the process chamber may be discharged to the outside of the process chamber. Then, by repeatedly performing the supply and discharge process of the transition metal precursor and the chalcogen precursor in a plurality of cycles, it is possible to form a transition metal chalcogen compound thin film of a desired thickness on the surface of the graphene thin film.

According to an exemplary embodiment of the present invention, the transition metal precursor is copper (Cu), tungsten (W), molybdenum (Mo), titanium (Ti), vanadium (V), zirconium (Zr), niobium (Nb), tel Rurium (Te), hafnium (Hf), tantalum (Ta), rhenium (Re), cobalt (Co), nickel (Ni), rhodium (Rh), palladium (Pd), iridium (Ir), technetium (Tc), It may include at least one of zinc (Zn), tin (Sn), and platinum (Pt).

According to an exemplary embodiment of the present invention, as the transition metal precursor, one suitable for an atomic layer deposition process may be used. The transition metal precursor may include a transition metal ligand. Specifically, the transition metal precursor may include a transition metal organoligand (ML; M is a transition metal, L is a ligand). The transition metal organic ligand is effectively adsorbed on the surface of the graphene thin film including two or more graphene layers, so that the transition metal chalcogen compound can be synthesized more quickly and easily on the graphene thin film. In the transition metal ligand, the ligand is nitrate, sulfate, phosphate, alkyl, alkenyl, alkynyl, phenyl, benzyl, halide, hydroxyl, carboxyl, carbonyl, vinyl, alkoxide, phosphine, amine, imine, imide, It may include at least one functional group of azide, azo, cyanate, silane, beta diketonate, beta ketoiminate, beta acetoacetate, carboxylate, amidinate, and diazadiene. However, the type of the ligand is not limited, and may be variously set according to the type of the transition metal and the conditions of the atomic layer deposition process.

According to an exemplary embodiment of the present invention, the transition metal precursor may include a transition metal halide. Specifically, the transition metal halide is MoF ₃ , MoF ₆ , MoF ₄ , Mo ₄ F ₂₀ , MoCl ₂ , MoCl ₃ , MoCl ₆ , MoCl ₄ , MoCl ₅ , MoBr ₃ , MoBr ₄ , MoI ₂ , MoI ₃ , MoI ₄ , WF ₆ , WF ₄ , [WF ₅ ] ₄ , WCl ₂ , WCl ₆ , WCl ₄ , [WCl ₅ ] ₂ , [W ₆ Cl ₁₂ ]Cl ₆ , WBr ₃ , WBr ₆ , WBr ₄ , WBr ₅ , W ₆ Br ₁₄ , WI ₂ , WI ₃ , WI ₄ , VF ₂ , VF ₃ , VF ₄ , VF ₅ , VCl _{2 , VCl 3 , VCl 4 , VBr 2 , VBr 3 , VBr 4 ,} VI ₂ , VI ₃ , VI ₄ , NbCl ₃ , NbCl ₄ , NbCl ₅ , NbBr ₄ , NbBr ₅ , NbI ₃ , NbI ₄ , NbI ₅ , TaF ₃ , [TaF ₅ ] ₄ , TaCl ₃ , TaCl ₄ , TaCl ₅ , TaBr ₃ , TaBr ₄ , TaBr ₅ , TaI ₄ , TaI ₅ , TiF ₂ , TiF ₃ , TiF ₄ , TiCl ₄ , TiCl ₃ , TiCl ₂ , TiBr ₃ , TiBr ₄ , HfCl ₄ , HfBr ₂ , HfBr ₄ , HfI ₃ , HfI ₄ , ZrF ₄ , ZrCl ₂ , ZrCl ₃ , ZrCl ₄ , ZrBr ₃ , ZrBr ₄ , ZrI ₂ , ZrI ₃ , ZrI ₄ , TcF ₆ , TcF ₅ , TcCl ₄ , TcCl ₆ , TcBr ₄ , ReF ₆ , ReF ₄ , ReF ₅ , ReF ₇ , Re ₃ Cl ₉ , ReCl ₅ , ReCl ₄ , ReCl ₆ , ReBr ₃ , ReBr ₄ , ReBr ₅ , ReI ₃ , ReI ₄ , CoF ₂ , CoF ₃ , CoF ₄ , CoCl ₂ , CoCl ₃ , CoBr ₂ , CoI ₂ , RhF ₃ , RhF ₆ , RhF ₄ , [RhF ₅ ] ₄ , RhCl ₃ , R hBr ₃ , RhI ₃ , IrF ₃ , IrF ₆ , IrF ₄ , [IrF ₅ ] ₄ , IrCl ₂ , IrCl ₃ , IrCl ₄ , IrBr ₂ , IrBr ₃ , IrBr ₄ , IrI ₂ , IrI ₃ , IrI ₄ , NiF ₂ , NiCl ₂ , NiBr ₂ , NiI ₂ , PdF ₂ , PdF ₄ , PdCl ₂ , PdBr ₂ , PdI ₂ , PtF ₆ , PtF ₄ , [PtF ₅ ] ₄ , PtCl ₂ , PtCl ₃ , PtCl ₄ , Pt ₆ Cl1 ₂ , PtBr ₂ , PtBr ₃ , PtBr ₄ , PtI ₂ , PtI ₃ , PtI ₄ , GaF ₃ , GaCl ₂ , GaCl ₃ , GaBr ₃ , GaI ₃ , SnF ₂ , SnF ₄ , SnCl ₂ , SnCl ₄ , SnBr ₂ , SnBr ₄ , SnI ₂ , and SnI ₄ may be included.

In addition, when copper is used as the transition metal, copper pivalate, Copper(II) dimethylamino ethoxide, Copper(II) diethylamino-2-propoxide, Copper(II) acetylacetonate, and Copper(II) are used as the transition metal precursors. ) trifluoroacetylacetonate, Copper(II) hexafluoroacetylacetonate, copper(II) bis(2,2,6,6-tetramethyl-3,5-heptanedionate), Copper(II) tert-butylacetoacetate, Bis(dimethylamino-2-propoxy)copper( II), Bis(1-dimethylamino-2-methyl-2-butoxy)copper(II), Bis(N,N'-di-sec-butylacetamidinato)dicopper(I), and Copper (I) Guanidinates It can be used, but the type of the copper precursor is not limited.

According to an exemplary embodiment of the present invention, the chalcogen precursor may include at least one of sulfur (S), selenium (Se), and tellurium (Te). Specifically, the chalcogen precursor may include a silyl-chalcogen compound. The silyl-chalcogen compound is effectively adsorbed on the surface of the graphene thin film including two or more graphene layers, so that the transition metal chalcogen compound can be synthesized more quickly and easily on the graphene thin film. The silyl-chalcogen compound may be silyl-sulfur, silyl-selenium or silyl-tellurium.

Specifically, silyl-sulfur is bis(trimethylsilyl)sulfide, bis(dimethylsilyl)sulfide, bis(triethylsilyl)sulfide, bis(diethylsilyl)sulfide, bis(phenyldimethylsilyl)sulfide, bis(t-butyldimethyl) silyl) sulfide, dimethylsilylmethyl sulfide, dimethylsilylphenyl sulfide, dimethylsilyl-n-butyl sulfide, dimethylsilyl-t-butyl sulfide, trimethylsilylmethyl sulfide, trimethylsilylphenyl sulfide, trimethylsilyl-n-butyl sulfide, and trimethyl and at least one of silyl-t-butylsulfide.

In addition, silyl-selenium is bis (trimethylsilyl) selenium, bis (dimethylsilyl) selenium, bis (triethylsilyl) selenium, bis (diethylsilyl) selenium, bis (phenyldimethylsilyl) selenium, bis (t-butyldimethyl) silyl) selenium, dimethylsilylmethyl selenium, dimethylsilylphenyl selenium, dimethylsilyl-n-butyl selenium, dimethylsilyl-t-butyl selenium, trimethylsilylmethyl selenium, trimethylsilylphenyl selenium, trimethylsilyl-n-butyl selenium, and trimethyl It may include at least one of silyl-t-butyl selenium.

In addition, silyl-tellurium is bis(trimethylsilyl)tellurium, bis(dimethylsilyl)tellurium, bis(triethylsilyl)tellurium, bis(diethylsilyl)tellurium, bis(phenyldimethylsilyl)tellurium, Bis(t-butyldimethylsilyl)tellurium, dimethylsilylmethyltellurium, dimethylsilylphenyltellurium, dimethylsilyl-n-butyltellurium, dimethylsilyl-t-butyltellurium, trimethylsilylmethyltellurium, trimethylsilylphenyl at least one of tellurium, trimethylsilyl-n-butyltellurium, and trimethylsilyl-t-butyltellurium.

In addition, as the chalcogen precursor, one suitable for an atomic layer deposition process may be used. For example, the chalcogen precursor is sulfur, hydrogen sulfide (H ₂ S), diethyl sulfide (diethyl sulfide), dimethyl disulfide (dimethyl disulfide), ethyl methyl sulfide (Ethyl methyl sulfide), (Et ₃ Si) ₂ S, selenium vapor, hydrogen selenide (H ₂ Se), diethyl selenide, dimethyl diselenide, ethyl methyl selenide, (Et ₃ Si) ) ₂ Se, telenium vapor, hydrogen telenide (H ₂ Te), dimethyl telluride, diethyl telluride, Ethyl methyl telluride and (Et3Si) ) may include at least one of 2Te. However, the type of the chalcogen precursor is not limited.

Figure 2 is a view schematically showing the form of a transition metal chalcogen compound layer according to an embodiment of the present invention. Specifically, (a) of Figure 2 shows the cross-section of the transition metal chalcogen compound layer, Figure 2 (b) shows the plane of the transition metal chalcogen compound layer, Figure 2 (c) is yes It is a diagram showing the plane of the fin layer. 2 shows an embodiment using copper as a transition metal and selenium as a chalcogen compound, wherein the yellow element represents copper and the pink element represents selenium. Referring to FIG. 2 , the synthesized copper selenide may have a honeycomb lattice structure similar to graphene.

According to an exemplary embodiment of the present invention, the transition metal chalcogen compound thin film may include a transition metal chalcogen compound layer of 1 or more and 15 or less. The transition metal chalcogen compound layer may be formed of a transition metal chalcogen compound formed by the reaction of the transition metal precursor and the chalcogen precursor. By using the atomic layer deposition process as described above, the number of transition metal chalcogen compound layers formed on the graphene thin film can be controlled. On the other hand, the number of the transition metal chalcogen compound layers included in the transition metal chalcogen compound thin film is not limited to the above-described range, the number of transition metal chalcogen compound layers according to the use of the synthesized transition metal chalcogen compound layer can be variously adjusted.

According to an exemplary embodiment of the present invention, the thickness of the transition metal chalcogen compound thin film may be 1.5 nm or more and 30 nm or less. The thickness of the transition metal chalcogen compound thin film may be controlled according to the number of transition metal chalcogen compound layers formed on the surface of the graphene thin film. On the other hand, the thickness of the transition metal chalcogen compound thin film is not limited to the above-described range, the thickness of the transition metal chalcogen compound thin film can be variously adjusted according to the use of the synthesized transition metal chalcogen compound.

According to an exemplary embodiment of the present invention, the transition metal chalcogen compound thin film may have a thickness gradient. Specifically, a graphene thin film is prepared by forming an upper graphene layer on a portion of the lower graphene layer, and a transition metal chalcogen compound layer is formed on the graphene thin film to form the transition metal chalcogen compound thin film. A thickness gradient can be formed. Through this, by performing the atomic layer deposition process under the same conditions, there is an advantage in the process of synthesizing a transition metal chalcogen compound thin film having a thickness gradient.

According to an exemplary embodiment of the present invention, on the graphene thin film, the transition metal chalcogen compound may be grown as a single crystal. Specifically, through atomic layer deposition, a transition metal chalcogen compound may be epitaxially grown on the graphene thin film.

When copper pivalate is used as a transition metal precursor and bis (triethylsilyl) selenium is used as a chalcogen precursor, copper selenide epitaxially grown on the graphene thin film has a klockmannite structure. can have Referring to FIG. 2, the copper selenide shown in FIG. 2(b) has a clochmannite structure, and the graphene shown in FIG. 2(c) has a honeycomb lattice structure. In addition, the mismatch ratio between the clochmannite structure of the copper selenide shown in (b) of FIG. 2 and the honeycomb lattice structure of the graphene shown in FIG. It may have the same lattice structure as graphene. That is, an exemplary embodiment of the present invention can effectively synthesize a transition metal chalcogen compound having excellent crystallinity by using a graphene thin film as a substrate. In addition, the graphene layer and the transition metal chalcogen compound layer are substantially identical in lattice structure to each other, so that the junction quality of the transition metal chalcogen compound layer to the graphene layer can be increased.

According to an exemplary embodiment of the present invention, the transition metal chalcogen compound thin film includes a plurality of nanoplates made of a transition metal chalcogen compound, and the growth direction of the transition metal chalcogen compound of the plurality of nanoplates is the same as each other. or may be different. Specifically, the transition metal chalcogen compound layer may include the plurality of nanoplates. In addition, directions in which the plurality of nanoplates grow may be the same or different from each other. For example, some of the plurality of nanoplates on a plane may grow in a first direction, and others may grow in a second direction opposite to the first direction. That is, the transition metal chalcogen compound layer may include nanoplates of the transition metal chalcogen compound grown in opposite directions.

According to an exemplary embodiment of the present invention, the transition metal chalcogen compound thin film may include a triangular nanoplate made of the transition metal chalcogen compound. Specifically, the transition metal chalcogen compound thin film may include at least a triangular nanoplate. The triangular nanoplate corresponds to a single crystal, so that electrons can easily move in a vertical direction. The transition metal chalcogen compound thin film including the triangular nanoplate can have high efficiency when applied to various devices such as thermoelectric elements, solar cells, and water decomposition catalysts, and can implement excellent reproducibility. . In addition, the nanoplate made of the transition metal chalcogen compound may have a polygonal structure such as a quadrangle, a pentagon, a hexagon, a parallelogram, and a trapezoid, and may have a non-polygonal structure having a spherical shape or some curved shape.

According to an exemplary embodiment of the present invention, the interatomic distances of the transition metal chalcogen compound may be 0.2 nm or more and 0.5 nm or less. Specifically, the interatomic distance of the transition metal chalcogen compound may be 0.2 nm or more and 0.45 nm or less, or 0.2 nm or more and 0.4 nm or less. The transition metal chalcogen compound having a valence distance satisfying the above range may have excellent crystallinity. On the other hand, the interatomic distance of the transition metal chalcogen compound included in one nanoplate may be different from the interatomic distance of the transition metal chalcogen compound included in the other nanoplate. In addition, the sizes of the plurality of nanoplates included in the transition metal chalcogen compound thin film may be different from each other.

According to an exemplary embodiment of the present invention, the transition metal chalcogen compound thin film may have a moire pattern (moire pattern). Specifically, as the nanoplate included in the transition metal chalcogen compound layer includes a transition metal chalcogen compound having excellent crystallinity, a moire pattern is formed on the portion of the transition metal chalcogen compound thin film where the nanoplate is located. can be implemented. In addition, since the crystal structure of the unit cell of the transition metal chalcogen compound and the unit cell structure of graphene are very similar, a moire pattern may appear on the transition metal chalcogen compound thin film.

Figure 3 is a view schematically showing a method for preparing a transition metal chalcogen compound on the oxidized graphene layer according to an embodiment of the present invention. Specifically, FIG. 3 is a view showing the reaction by providing copper pivalate, a transition metal precursor, on the surface of the oxidized graphene layer after oxidizing the surface of the graphene layer provided in the outermost layer of the graphene thin film. to be.

According to an exemplary embodiment of the present invention, the method for preparing the transition metal chalcogen compound may further include oxidizing the surface of the graphene layer. By oxidizing the surface of the graphene layer, the synthesis efficiency and crystallinity of the transition metal chalcogen compound may be further improved. As the surface of the graphene layer is oxidized, hydroxyl groups and/or tube oxides may be bonded to the surface of the graphene layer. As shown in FIG. 3 , the hydroxyl group and the transition metal precursor bonded to the surface of the graphene layer may form a stable transition state. In addition, during the purging process, relatively stable carboxylic acids are removed, and at the same time, copper may be stably adsorbed to the surface of the graphene layer through bonding with oxygen. Through this, the transition metal chalcogen compound can be more effectively synthesized on the surface of the oxidized graphene layer.

As a method of oxidizing the surface of the graphene layer, a method of oxidizing graphene in the art may be used. For example, through a method of heating while supplying oxygen to the graphene thin film, the surface of the graphene layer included in the graphene thin film may be oxidized.

According to an exemplary embodiment of the present invention, the transition metal chalcogen compound may be represented by the following formula (1).

[Formula 1]

M _x x _y

In the above formula, M is a transition metal, X is a chalcogen element, and x:y is 1:1 to 2:1. In Formula 1, x and y may mean a ratio of the weight % of the transition metal element and the chalcogen element.

By using the atomic layer deposition method as described above, it is possible to control the composition of the transition metal chalcogen compound formed on the graphene thin film. Specifically, the transition metal chalcogen compound synthesized on the graphene foil may be synthesized stoichiometrically or non-stoichiometrically.

According to an exemplary embodiment of the present invention, copper selenide may be synthesized by using the method for preparing the transition metal chalcogen compound. Specifically, CuSe and/or Cu ₂ Se may be synthesized.

Hereinafter, examples will be given to describe the present invention in detail. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not to be construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely explain the present invention to those of ordinary skill in the art.

Example 1

Graphene was synthesized on a 25 μm-thick copper foil (purity 99.7%) by chemical vapor deposition (CVD). Specifically, a copper foil was rolled into a 1.5-inch quartz tube (inner quartz tube), an asbestos furnace was placed in a 7-inch quartz tube (outer quartz tube), and a vacuum (10 ^-4 Torr or less) condition was created. Then, one layer of graphene was synthesized through a process of annealing-synthesis (growth)-cooling step. Specifically, in the heating step, hydrogen gas (20 sccm, 10 ^-2 Torr or less) was supplied and heated from room temperature to 1000° C. for 1 hour. After that, while maintaining the state of supplying hydrogen gas (20 sccm) in the synthesis step, while supplying methane gas (10 sccm) at the same time, it was maintained at 1000 ° C. for 30 minutes (hydrogen gas + methane gas, 10 ^-1 Torr or less) . Then, while maintaining the supply of hydrogen gas (10 ^-2 Torr or less) in the cooling step, the supply of methane gas was stopped, and the asbestos furnace was cooled to room temperature. After cooling was completed, the vacuum condition was released and the copper foil in which the graphene layer was synthesized was taken out.

Thereafter, a process of PMMA coating-RIE etching-APS etching-rinsing-transfer was performed to transfer one graphene layer onto the substrate. Specifically, one side of the copper foil in which the graphene layer was synthesized was spin-coated with PMMA dissolved in chlorobenzene, and the opposite side was etched (etched) of the graphene layer using reactive ion etching (RIE) equipment. Then, APS (Ammonium persulfate) was dissolved in water and the copper layer was melted by wet etching. Then, the remaining PMMA (Poly(methyl methacrylate))-coated graphene layer was transferred to DI water and washed. The washed graphene layer was transferred onto a SiO ₂ /Si substrate having a thickness of about 285 nm to prepare a substrate having a first graphene layer.

Then, after etching the PMMA layer with acetone, the PMMA coating-RIE etching-APS etching process is performed on the layer again, and the second graphene layer washed with DI water is transferred to the first graphene layer. An island-shaped second graphene layer was provided on a portion of the first graphene layer.

Copper pivalate was used as a transition metal precursor, and bis (triethylsilyl) selenium was prepared as a chalcogen precursor. Thereafter, the substrate provided with the first graphene layer and the second graphene layer was placed in a vacuum chamber, and copper pivalate and bis(triethylsilyl)selenium were sequentially supplied to the vacuum chamber maintained in a vacuum state. At this time, copper pivalate (evaporation temperature: 160 ℃) was supplied at 30 SCCM, bis (triethylsilyl) selenium (evaporation temperature: 45 ℃) was supplied at 50 SCCM, argon gas as a purge gas 50 SCCM was supplied, and the internal temperature of the vacuum chamber was maintained at about 170 °C. By repeating the atomic layer deposition process 500 times, copper selenide, a transition metal chalcogen compound, was synthesized on the graphene thin film.

Example 2

In the same manner as in Example 1, a substrate provided with a first graphene layer and a second graphene layer was prepared. Thereafter, copper, which is a transition metal chalcogen compound, on the graphene thin film in the same manner as in Example 1, except that the internal temperature of the vacuum chamber was maintained at about 160° C. and the atomic layer deposition process was repeated 1,000 times. Selenide was synthesized.

Example 3

In the same manner as in Example 1, a substrate provided with a first graphene layer and a second graphene layer was prepared. Thereafter, by transferring the third graphene layer on the second graphene layer through the same method as the method described above in Example 1, the first graphene layer, the second graphene layer, and the third graphene layer are provided. The substrate was prepared. Thereafter, copper selenide, a transition metal chalcogen compound, was synthesized on the graphene thin film in the same manner as in Example 1.

Example 4

In the same manner as in Example 1, a substrate provided with a first graphene layer and a second graphene layer was prepared.

Thereafter, the substrate provided with the graphene thin film was put into a vacuum furnace, oxygen gas was supplied at a flow rate of 100 ml/hr, and the substrate was heated at a temperature of 500° C. for 1 hour, so that graphene The surface of the thin film was oxidized.

Then, in the same manner as in Example 1, an atomic layer deposition process was performed to synthesize copper selenide, which is a transition metal chalcogen compound, on a graphene thin film.

Comparative Example 1

In the same manner as in Example 1, a substrate provided with a first graphene layer was prepared. Thereafter, an atomic layer deposition process was performed in the same manner as in Example 1 to synthesize copper selenide, which is a transition metal chalcogen compound, on the first graphene layer.

Experimental example

Using the following experimental equipment, the physical properties of the synthesized transition metal chalcogen compound were observed and evaluated.

1. SEM: JSM-7600F; JEOL

2. HR-TEM: 80keV TEM (JEM-2100F; JEOL)

3. Cs-STEM, EDS, FFT: Cs-Corrected STEM (JEM-ARM200F; JEOL Corporation)

4. XPS: AXIS-HSi, KRATOS

5. CuSe height measurement: A home-made AFM (home-made AFM) operating in a tapping mode condition was used, and was performed with a silicon probe (Nanosensors, PPP-NCHR, resistance 300 kHz or less).

6. Raman: Micro-Raman spectroscopy measurement (inVia confocal Raman microscope, Renishaw) was used, and a laser with a wavelength of 514.5 nm was used.

4 is a view showing an image of the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. Specifically, FIGS. 4 a to d and g are TEM images of a graphene thin film provided with CuSe nanoplates, and FIG. 4 e is a Fast Fourier transform (FFT) of CuSe nanoplates in the blue square region of FIG. 4d . image, f of FIG. 4 is an FFT image of the graphene layer in the red square area of d of FIG. 4 , and h of FIG. 4 is an FFT image of the CuSe nanoplate of the blue square area of FIG. 4 g. i is an FFT image of the graphene layer in the red square region in g of FIG. 4 .

Referring to FIGS. 4 a to d and g, CuSe nanoplates with excellent crystallinity were synthesized, and it was confirmed that a moire pattern was observed in the transition metal chalcogen compound thin film. In addition, it was confirmed that CuSe nanoplates were grown in a triangular shape. In addition, referring to e and f of FIG. 4 and h and i of FIG. 4 , it was confirmed that the lattice form of the synthesized CuSe and graphene was very similar.

5 is a view showing an image of one CuSe nanoplate observed in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. Specifically, FIG. 5a is a TEM image of a CuSe nanoplate showing a moire pattern, FIG. 5b is an inverted FFT image of the CuSe nanoplate in the light blue square region of FIG. 5a, and FIG. 5c is FIG. Fig. 5 is a view showing a line-profile along the line c in b, Fig. 5 d is a TEM image of a CuSe nanoplate showing a moire pattern, and Fig. 5 e is a light blue rectangle in Fig. 5 d It is an inverted FFT image of the CuSe nanoplate of the region, and FIG. 5 f is a diagram showing a line-profile along the f line in FIG. 5E .

Referring to FIG. 5 , CuSe nanoplates with excellent crystallinity were synthesized, and it was confirmed that the interatomic distance in one CuSe nanoplate included in the transition metal chalcogen compound thin film corresponds to 0.227 nm.

6 is a view showing an image of observing two CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. Specifically, Fig. 6a is a TEM image of one CuSe nanoplate showing a moire pattern, Fig. 6b is a magnified TEM image of the CuSe nanoplate in the sky-blue square region of Fig. 6a, and Fig. 6c is the inverted FFT image of FIG. 6 b, FIG. 6 d is a TEM image of another CuSe nanoplate showing a moire pattern, and FIG. It is an enlarged TEM image, and f of FIG. 6 is an inverted FFT image of FIG. 6e .

Referring to FIG. 6 , CuSe nanoplates with excellent crystallinity are synthesized, and the interatomic distance corresponds to 0.219 nm in one CuSe nanoplate included in the transition metal chalcogen compound thin film, and the original CuSe nanoplate in the other CuSe nanoplate. It was confirmed that the inter-signal distance corresponds to 0.224 nm. That is, it can be confirmed that the interatomic distances of the synthesized CuSe nanoplates are different from each other.

7 is a view showing an image of another CuSe nanoplate included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. Figure 7 shows an image of the observation of the CuSe nanoplate having a dodecahedron (dodecahedron) structure included in the transition metal chalcogen compound thin film prepared in Example 1. Specifically, FIG. 7a is a dark-field STEM image of a dodecahedron-structured CuSe nanoplate, and FIG. 7b is a bright-field STEM image of a dodecahedral-structured CuSe nanoplate. 7 c is a TEM image of FIG. 7 b , FIG. 7 d is an enlarged TEM image of FIG. 7 c, FIG. 7 e is an FFT image of a dodecahedral CuSe nanoplate, and FIG. f is the inverted FFT image of FIG. 7e.

Referring to FIG. 7 , it was confirmed that CuSe nanoplates having a dodecahedral structure with excellent crystallinity were synthesized, and the valence distance of the CuSe nanoplates was 0.352 nm.

8 is a view showing an image of observing two CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. 8 shows an image of two CuSe nanoplates having a hexahedron structure included in the transition metal chalcogen compound thin film prepared in Example 1.

Specifically, FIG. 8a is a TEM image of any CuSe nanoplate having a hexahedral structure, FIG. 8b is an enlarged TEM image of FIG. 8a , and FIG. 8c is a hexahedral structure CuSe It is an FFT image of the nanoplate, and d of FIG. 8 is an inverted FFT image of FIG. 8 c. FIG. 8e is a TEM image of another CuSe nanoplate having a hexahedral structure, FIG. 8f is an enlarged TEM image of FIG. 8e, and FIG. 8g is a hexahedral structure of CuSe nanoplate It is an FFT image, and the h of FIG. 8 is the inverted FFT image of the g of FIG.

Referring to FIGS. 8A to 8D , it was confirmed that CuSe nanoplates having a hexahedral structure with excellent crystallinity were synthesized, and the valence distance of the CuSe nanoplates was 0.342 nm. Also, referring to e to h of FIG. 8 , it was confirmed that CuSe nanoplates having a hexahedral structure with excellent crystallinity were synthesized, and the valence distance of the CuSe nanoplates was 0.368 nm.

9 is a view showing an image of observing a plurality of CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. Specifically, FIGS. 9 a and b show the growth direction of CuSe in any one region of the transition metal chalcogen compound thin film, and FIGS. 9 c and d show the growth direction of CuSe in another region of the transition metal chalcogen compound thin film. it has been shown Referring to FIG. 9 , it was confirmed that CuSe was epitaxially grown on the surface of the graphene thin film. In addition, referring to a, b, c, and d of FIG. 9 , the CuSe nanoplates grown in the upper direction (blue arrow direction) and the CuSe nanoplates grown in the lower direction (red arrow direction) were synthesized together with respect to the x-axis. Confirmed.

10 is a scanning transmission electron microscope (STEM) image and energy dispersive X-ray spectroscopy (EDS) analysis image of a plurality of CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. to be. 10 a, b, e and f are images in the same area, and c, d, g, and h are images in the same area. Specifically, a and c of FIG. 10 are STEM images in dark field mode, b and d are STEM images in bright field mode, and e is an image of copper element mapped using EDS in the regions of a and b, f is an image in which selenium element is mapped using EDS in regions a and b, g is an image in which copper element is mapped using EDS in regions c and d, h is EDS in regions c and d It is an image mapped with selenium element using

Referring to FIG. 10 , it was confirmed that a triangular CuSe nanoplate having excellent crystallinity was synthesized. In addition, in e and g of FIG. 10 , it was confirmed that the copper element contained in the CuSe nanoplate was 47.77 wt%, the selenium element was 45.10 wt%, and the sodium element was 7.13 wt%. In addition, in g and h of FIG. 10 , it was confirmed that the copper element contained in the CuSe nanoplate was 49.90 wt% and the selenium element was 51.10 wt%.

11 is a view showing STEM images and EDS analysis images of a plurality of CuSe nanoplates included in the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. Specifically, in FIG. 11, a is a STEM image of dark field mode, b is a STEM image of bright field mode, c is an image of copper element mapped using EDS in the box region of a, and d is a box of a. This is an image of selenium element mapping using EDS in the region.

Referring to FIG. 11 , it was confirmed that a rectangular CuSe nanoplate having excellent crystallinity was synthesized. In addition, in c and d of FIG. 11 , it was confirmed that the copper element contained in the CuSe nanoplate was 51.91 wt% and the selenium element was 48.09 wt%.

In addition, referring to FIGS. 10 and 11 , it was confirmed that the component ratio of the copper element and the selenium element in CuSe synthesized in Example 1 was about 1:1.

12 is a graph showing the results of XPS (x-ray photoelectron spectroscopic analysis) of the transition metal chalcogen compound thin film prepared in Example 1 of the present invention. Referring to FIG. 12 , it was confirmed that a copper element and a selenium element were present on the graphene thin film.

13 is a view showing an image of the transition metal chalcogen compound thin film prepared in Example 2. Specifically, a of FIG. 13 is an SEM image showing that the transition metal chalcogen compound is synthesized on the first graphene layer (MLG) region and the second graphene layer (BLG) region, and b is the first graphene layer It is an SEM image showing the boundary between the (MLG) region and the second graphene layer (BLG) region, and c is a SEM image showing that the transition metal chalcogen compound is synthesized on the first graphene layer (MLG) region.

13A and 13B , it was confirmed that a larger amount of CuSe was synthesized on the second graphene layer compared to the first graphene layer even under the same ALD process conditions. In addition, it was confirmed that the second graphene layer BLG appeared darker than the first graphene layer MLG. This is because, compared to the first graphene layer, a larger amount of CuSe was synthesized on the second graphene layer, and the synthesized CuSe was merged and grown.

14 is a view showing a topography image of the transition metal chalcogen compound thin film prepared in Examples 1 and 2 of the present invention and the height profile of the synthesized CuSe. Specifically, in FIG. 14 a is a topographical image of the transition metal chalcogen compound thin film prepared in Example 1, b is a height profile of the synthesized CuSe in the blue dotted line portion of a, c is a topographical image in Example 2 It is a topographic image of the prepared transition metal chalcogen compound thin film, and d shows the height profile of the synthesized CuSe in the blue dotted line part of c.

Referring to FIG. 14 b , compared to the height of CuSe synthesized on the first graphene layer (MLG) in Example 1, the height of CuSe synthesized on the second graphene layer (BLG) is about 3.5 nm on average. higher was confirmed. Also, referring to d of FIG. 14 , the height of CuSe synthesized on the second graphene layer (BLG) compared to the height of CuSe synthesized on the first graphene layer (MLG) in Example 2 is about on average 3.3 nm higher was confirmed. Considering that the thickness of the first graphene layer is about 0.34 nm, it can be seen that a thicker transition metal chalcogen compound layer is synthesized on the second graphene layer.

15 is a view showing the Raman spectrum analysis results of the transition metal chalcogen compound thin film prepared in Comparative Example 1, Example 1 and Example 3 of the present invention. Specifically, FIG. 15 a shows the Raman spectrum of CuSe synthesized on the first graphene layer (MLG) of Comparative Example 1, and b shows the Raman spectrum synthesized on the second graphene layer (BLG) of Example 1 It shows the Raman spectrum of CuSe, and c shows the Raman spectrum of CuSe synthesized on the first graphene layer (MLG), the second graphene layer (BLG), and the third graphene layer (TLG) of Example 3 will be.

Referring to FIG. 15 , a peak indicating CuSe (stretching mode of Cu-Se bond in clochmannite structure) was confirmed at 267.8 cm ^-1 , and the peak was observed in the second graphene layer compared to the first graphene layer. It was confirmed that the peak appeared stronger in the third graphene layer compared to the second graphene layer. That is, as the number of graphene layers increases, it can be seen that CuSe is more effectively synthesized.

16 is a view showing an image of observing the transition metal chalcogen compound thin film prepared in Comparative Examples 1 and 4 of the present invention. 16 a and c are SEM images of CuSe synthesized on the first graphene layer of Comparative Example 1, and b and d are SEM images of CuSe synthesized on the second graphene layer having an oxidized surface of Example 4 .

Referring to FIG. 16 , in the case of Example 4 in which the surface of the graphene layer was oxidized, compared to Comparative Example 1, a larger amount of CuSe could be synthesized under the same ALD process conditions, and CuSe was effectively synthesized to form a larger triangle. It was confirmed that nanoplates of

17 is a view showing a DFT (density functional theory) calculated value of absorbed energy when CuSe is synthesized in the graphene layer of the first layer and the graphene layer of the second layer. Specifically, a and b of FIG. 17 show the absorbed energy calculated when CuSe is synthesized in the graphene layer of one layer, and c and d are the absorbed energy calculated when CuSe is synthesized in the graphene layer of the second layer. is shown.

In order to confirm whether CuSe can be synthesized more effectively in the graphene layer of the second layer than in the graphene layer of the first layer, the density functional theory (DFT) with the periodic boundary condition was conducted. Based on quantum mechanical calculations were performed. Referring to FIG. 2 , in the z-axis cross section, clochmannite CuSe has a hexagonal crystal structure and has a pseudo h-BN (pseudo h-BN) structure composed of Cu and Se, so clochmannite CuSe is It can be grown on the fin first. Comparing the horizontal lattice constant, graphene (a=b=2.46 Å) and CuSe (a=b=3.938 Å) are 8 times that of graphene unit cell (19.68 Å) and CuSe unit cell The lattice mismatch of 5 times (19.69 Å) is less than 1%. Therefore, in order to compare the stability of CuSe according to the number of graphene layers, the adsorption energy of clochmannite CuSe in the first graphene layer and the second graphene layer was calculated.

17, in both Cu-centered and Se-centered cases, the adsorption energy (E _ads ) of clochmannite CuSe is the graphene layer of one layer (-5.75 eV). and -5.06 eV) in the two-layer graphene layer (-6.34 eV and -6.43 eV), suggesting that CuSe can be grown more stably in the two-layer graphene layer.

The above detailed description illustrates and describes the present invention. In addition, the foregoing is merely to show and describe preferred embodiments of the present invention, and as described above, the present invention can be used in various other combinations, modifications and environments, the scope of the concepts of the invention disclosed herein, and the writing Changes or modifications are possible within the scope equivalent to one disclosure and/or within the skill or knowledge in the art. Accordingly, the detailed description of the present invention is not intended to limit the present invention to the disclosed embodiments. In addition, the appended claims should be construed to include other embodiments as well.

Claims (13)

forming a graphene thin film including two or more graphene layers on a substrate; and
Forming a transition metal chalcogen compound on the graphene thin film from a transition metal precursor and a chalcogen precursor using atomic layer deposition to form a transition metal chalcogen compound thin film; Preparation of a transition metal chalcogen compound comprising Way.
According to claim 1,
The graphene thin film is a method for producing a transition metal chalcogen compound that is formed on the substrate by chemical vapor deposition.
According to claim 1,
The graphene thin film is a method for producing a transition metal chalcogen compound comprising 2 or more and 10 or less graphene layers.
According to claim 1,
The thickness of the graphene thin film is 0.3 nm or more and 5 nm or less. Method for producing a transition metal chalcogen compound.
According to claim 1,
The transition metal precursor is copper (Cu), tungsten (W), molybdenum (Mo), titanium (Ti), vanadium (V), zirconium (Zr), niobium (Nb), tellurium (Te), hafnium (Hf) , tantalum (Ta), rhenium (Re), cobalt (Co), nickel (Ni), rhodium (Rh), palladium (Pd), iridium (Ir), technetium (Tc), zinc (Zn), tin (Sn) And platinum (Pt) method for producing a transition metal chalcogen compound comprising at least one.
According to claim 1,
The chalcogen precursor is a method of producing a transition metal chalcogen compound comprising at least one of sulfur (S), selenium (Se), and tellurium (Te).
According to claim 1,
The transition metal chalcogen compound thin film is a method of producing a transition metal chalcogen compound comprising one or more of one or more and 15 or less transition metal chalcogen compound layer.
According to claim 1,
The thickness of the transition metal chalcogen compound thin film is 1.5 nm or more and 30 nm or less.
The method of claim 1,
On the graphene thin film, the transition metal chalcogen compound is a method for producing a transition metal chalcogen compound to grow as a single crystal.
According to claim 1,
The transition metal chalcogen compound thin film,
It includes a plurality of nanoplates made of a transition metal chalcogenide compound,
The growth direction of the transition metal chalcogen compound of the plurality of nanoplates is the same or different from each other, the method for producing a transition metal chalcogen compound.
According to claim 1,
The transition metal chalcogen compound thin film,
A method for producing a transition metal chalcogen compound comprising a triangular nanoplate made of the transition metal chalcogen compound.
According to claim 1,
Method for producing a transition metal chalcogen compound further comprising the step of oxidizing the surface of the graphene layer.
According to claim 1,
The transition metal chalcogen compound is a method for preparing a transition metal chalcogen compound represented by the following formula (1):
[Formula 1]
M _x x _y
In the above formula, M is a transition metal, X is a chalcogen element, and x:y is 1:1 to 2:1.

Images