Method of manufacturing light-gated element including transition metal dichalcogenide grown to large area as light sensing layer

Abstract

To provide a light-gated element including a light sensing layer capable of responding to light stimulation and exhibiting neuromorphic characteristics, and a method of manufacturing the same.SOLUTION: A method of manufacturing a light-gated element comprises: preparing a first heating furnace and a second heating furnace spaced apart from each other in the same space; positioning a second precursor, which is prepared by mixing tungsten trioxide (WO3) as a transition metal oxide and sodium chloride (NaCl) as a metal halide salt in the second heating furnace, and a substrate to be adjacent to the second precursor; forming a light sensing layer including a transition metal dichalcogenide flake on top of the substrate; and performing vapor deposition of a source electrode and a drain electrode to form junctions in the light sensing layer; and forming a gate electrode under the substrate; where a mixing ratio of the transition metal oxide and the metal halide salt is between 5:1 and 7:1 by weight, and where the light-gated transistor is a logic element that performs an AND or OR logical operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical gate element, and more particularly to an optical gate element including a transition metal chalcogenide as a photosensitive layer, and a method for manufacturing the same. [Background technology]

[0002] Research into autonomous driving began in the 1970s, and with the emergence of deep learning technology in the 2010s, technological development has progressed rapidly, and as we go through the COVID-19 pandemic, autonomous driving technology is developing even faster. To address the core technologies of "artificial intelligence" and "safety" of the future smart mobility industry, the importance of sensor element technology that recognizes lanes and obstacles ahead of the vehicle, and artificial neuron network processing devices equipped with neuromorphic technology that simultaneously processes information in parallel for cognition, perception, and calculation, similar to the neuron structure and behavior of the human brain, is becoming increasingly important. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention has been devised to solve the above-mentioned problems, and its purpose is to provide an optical gate element having a photosensitive layer that can respond to optical stimuli and exhibits neuromorphic properties, and a method for manufacturing the same. [Means for solving the problem]

[0004] In order to achieve the above technical objectives, a manufacturing method of an optical gate element according to a preferred embodiment of the present invention includes the steps of: preparing a first heating furnace and a second heating furnace arranged apart from each other in the same space; placing a first precursor containing a chalcogen material in the first heating furnace; placing a second precursor containing a mixture of a transition metal oxide and a metal halide salt and a substrate adjacent to the second precursor in the second heating furnace; heating the first heating furnace and the second heating furnace to different temperatures and performing molten salt assisted thermal chemical vapor deposition to form a photosensitive layer containing at least one transition metal dichalcogenide flake on the substrate; and depositing electrodes to form at least two or more junction sites on the photosensitive layer.

[0005] The mixing ratio of the transition metal oxide and the metal halide salt may be 4:1 to 8:1 by weight.

[0006] The metal halide salt may be represented by the general formula AZ or AZ2, where A is an alkali metal or alkaline earth metal, and Z is a halogen element.

[0007] The metal halide salt may include at least one selected from the group consisting of NaCl, NaBr, KCl, KBr, LiCl, LiBr, CaCl2, MgCl2, CaB2, MgBr2, and combinations thereof.

[0008] In the step of forming the photosensitive layer, the temperature of the first heating furnace may be 500°C or higher and lower than 700°C, and the temperature of the second heating furnace may be 700°C or higher and lower than 900°C.

[0009] The transition metal dichalcogenide flakes may be monolayered or bilayered or more.

[0010] The transition metal dichalcogenide flakes contained in the photosensitive layer may have an average horizontal length of 10 to 100 μm.

[0011] The electrode may include a metal or a metal compound, and the metal or metal compound may include at least one metal element selected from the group consisting of Ti, Ni, Au, Ag, and combinations thereof.

[0012] In order to achieve the above technical objectives, an optical gate element according to a preferred embodiment of the present invention comprises a photosensitive layer disposed on a substrate and containing at least one or more transition metal dichalcogenide flakes, and a plurality of electrodes disposed on the photosensitive layer and spaced apart from each other.

[0013] The element may be a logic element that derives current characteristics associated with fluctuations in at least one of optical power applied in pulses from the outside and voltage applied to the gate electrode, and performs logical operations of AND, OR, and summation operations by applying optical power with the derived current characteristics.

[0014] The element may be an artificial synapse element having synaptic characteristics that derive current characteristics associated with fluctuations in at least one of optical power applied in pulses from the outside and voltage applied to the gate electrode, and electrically mimic the synaptic response of a neuron with the derived current characteristics.

[0015] The synaptic response of the neuron may include a learning (potentiation) and forgetting (depression) response caused by a light stimulus applied in a pulsed manner.

[0016] The transition metal dichalcogenide flakes may be monolayered or bilayered or more.

[0017] The transition metal dichalcogenide flakes contained in the photosensitive layer may have an average horizontal length of 10 to 100 μm.

[0018] The electrode may include a metal or a metal compound, and the metal or metal compound may include at least one metal element selected from the group consisting of Ti, Ni, Au, Ag, and combinations thereof. [Effects of the Invention]

[0019] According to the present invention as described above, transition metal dichalcogenide flakes manufactured by the molten salt assisted thermal chemical vapor deposition method according to a preferred embodiment of the present invention can be grown uniformly and evenly on a large substrate to a size of several to several hundred micrometers, and an optical gate device using this as a photosensitive layer can perform logical operations such as AND, OR, and summation in response to optical stimuli, and has the effect of being able to perform low-power synaptic operation reactions.

[0020] The effects of the present invention are not limited to the effects described above, and include other effects that are not explicitly mentioned, which are clearly understandable to those skilled in the art from the entire description of the specification. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram showing a cross section of an optical gate element according to an embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram of a furnace used to manufacture a transition metal dichalcogenide sheet using a molten salt-assisted thermal chemical vapor deposition (SA-CVD) method according to one embodiment of the present invention. [Figure 3] 1A shows an optical photograph of a substrate on which transition metal dichalcogenide flakes have been grown by a molten-salt-assisted thermal chemical vapor deposition method according to Preparation Example 1 of the present invention, its (b) optical microscope image, (c) coverage (%) over time of thermal chemical vapor deposition, and (d) X-ray photoelectron spectroscopy (XPS) results of the transition metal dichalcogenide flakes grown by thermal chemical vapor deposition. [Figure 4](a) Atomic force microscopy (AFM) results of the transition metal dichalcogenide flakes according to Example 1 of the present invention, (c) its height profile, (b) Kelvin probe force microscope (KPFM) image and its contact potential difference (CPD) profile. [Figure 5] FIG. 1 shows (a) Raman analysis of single-layer (1L), double-layer (2L), triple-layer (3L), and multi-layer (Multi-L) transition metal dichalcogenide flakes synthesized by molten-salt-assisted thermal chemical vapor deposition according to Preparation Example 1 of the present invention; (b) Raman intensity mapping of the single-layer transition metal dichalcogenide flakes in the E1 2g vibration mode (251 cm-1); (c) photoluminescence (PL) results for the transition metal dichalcogenide flakes as a function of the number of layers; and (d) photoluminescence intensity mapping of the single-layer transition metal dichalcogenide flakes on a SiO2 substrate. [Figure 6] 1 shows (a) a high-resolution transmission electron microscope (HRTEM) image of a SiO2 / WSe2 / Pt cross-sectional layer of transition metal dichalcogenide flakes synthesized by a molten-salt-assisted thermal chemical vapor deposition method according to Preparation Example 1 of the present invention, and (b) an energy dispersive X-ray spectroscopy (EDS) image of the same. [Figure 7] 1 shows optical photographs of transition metal dichalcogenide flakes synthesized using a 2x2 inch substrate by the molten salt-assisted thermal chemical vapor deposition method according to Preparation Example 1 of the present invention, and 25 locations used for photoluminescence (PL) measurements. [Figure 8]Transition metal dichalcogenide flakes synthesized using a 2x2 inch substrate by the molten salt assisted thermal chemical vapor deposition method of Preparation Example 1 were grown at 25 locations within the substrate. (a) Raman spectra at approximately 250 cm-1 and 260 cm-1, corresponding to the in-plane vibration mode (E12g) and out-of-plane vibration mode (A1g), and (b) photoluminescence (PL) results of the SiO2 substrate (1.62 eV) were collected. [Figure 9] 1 shows (a) a schematic diagram and circuit diagram of an optical gate device including a photosensitive layer of transition metal dichalcogenide flakes synthesized by a molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention, used as a conventional back-gated transition metal dichalcogenide field effect transistor (back-gated WSe2 FET), (b) p-type transmission characteristics measured by swiping VBG (-50V to +50V) at a constant VDS (1V), and (c) output IV results when swiping from -10V to +10V at different gate biases. [Figure 10] FIG. 1 shows (a) a schematic diagram and a circuit diagram of an optical gate device including a photosensitive layer of transition metal dichalcogenide flakes synthesized by a molten-salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention, in which optical power of 405 nm wavelength is applied; (b) transmission characteristics under different optical gate powers; and (c) output IV results under various optical gate powers ranging from 0.2 to 1.0 mW under VDS swipe from −10 V to +10 V under threshold optical power. [Figure 11] The optical gate device includes a photosensitive layer of transition metal dichalcogenide flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention. (a) Dynamic operation mode under pulse modulation of light irradiation at threshold light power, (b) Logic operation based on a single device that simultaneously inputs electrical gating and light gating, and (c) Brain-inspired synaptic function mode at threshold light power. [Figure 12](a) Dynamic photoresponse results generated by a laser source with a wavelength of 405 nm and a power of 0.2-0.8 mW / cm2, (b) photoresponse results across an operating frequency spectrum ranging from 1.4 Hz to 0.1 Hz, and (c) response characteristics of an optical gate device including a transition metal dichalcogenide flake as a photosensitive layer synthesized by a molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention. [Figure 13] 1 shows (a) the response of an optical gate device to each laser power and (b) the specific detectability analysis for each bias across the channel, of the device including the transition metal dichalcogenide flakes synthesized by the molten salt assisted thermal chemical vapor deposition method according to Example 1 of the present invention as a photosensitive layer. [Figure 14] 1 is an analysis of a transistor logic using an optical gate device including a photosensitive layer of transition metal dichalcogenide flakes synthesized by a molten salt assisted thermal chemical vapor deposition method according to Example 1 of the present invention. [Figure 15] 1 shows (a) excitatory postsynaptic behavior as a function of the number of pulses under a positive bias of the back gate electric field, (b) inhibitory postsynaptic behavior as a function of the number of pulses under a negative bias of the back gate electric field, and (c) optimized excitatory postsynaptic current (EPSC) and inhibitory postsynaptic current (IPSC) characteristics for an optical gate device including, as a photosensitive layer, transition metal dichalcogenide flakes synthesized by a molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention. [Figure 16]1 shows (a) EPSC and IPSC characteristics as a function of pulse duration for an optical gate device including, as a photosensitive layer, transition metal dichalcogenide flakes synthesized by the molten-salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention, and (b) Paired pulse facilitation (PPF: Paired pulse depression, a phenomenon in which, when a presynaptic cell is stimulated consecutively, the second synaptic transmission is facilitated compared to the first synaptic transmission) and PPD (Paired pulse depression, a phenomenon in which, when a presynaptic cell is stimulated consecutively, the second synaptic transmission is depressed compared to the first synaptic transmission) characteristics of the optical gate device. [Figure 17] (a) Normalized potentiation and depression results under various gate electric fields using optimized laser pulses and (b) normalized potentiation and depression results for nonlinearity analysis of an optical gate device including a transition metal dichalcogenide flake as a photosensitive layer synthesized by a molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The advantages and features of the present invention, as well as methods for achieving them, will become more apparent with reference to the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the technical concept of the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The following embodiments are provided merely to fully convey the technical concept of the present invention and to fully convey the scope of the present invention to those skilled in the art. The technical concept of the present invention is only defined by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0023] Furthermore, unless otherwise specified herein or clearly contradictory to the context, all terms used in this specification, including technical and scientific terms, can be used in the sense commonly understood by those skilled in the art to which this invention belongs. In addition, commonly used terms and dictionary-defined terms should not be construed as ideal or overly formal unless expressly defined in this application. 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 terms unless the context clearly dictates otherwise.

[0024] The terms "comprises," "has," "includes," and "comprises," as used herein, unless otherwise specified, are to be construed as open-ended terms (i.e., meaning "including, but not limited to") and merely indicate the presence of the components in question; a referenced component, step, operation, and / or element is not to be understood as excluding the presence or addition of one or more other components, steps, operations, and / or elements.

[0025] Optical gate devices containing transition metal dichalcogenides as photosensitive layers. FIG. 1 is a schematic diagram showing a cross section of an optical gating element according to one embodiment of the present invention.

[0026] Referring to FIG. 1, a light-gated transistor (LGT) 100 may include a photosensitive layer 120 including a two-dimensional semiconductor material disposed on a substrate 110, and a plurality of electrodes 130 disposed on the photosensitive layer 120 and spaced apart from one another.

[0027] The substrate 110 can be a semiconductor substrate such as silicon or SOI (Silicon-on-insulator) as a semiconductor material, and more specifically, a silicon substrate 111 with a dielectric layer 112 having a thickness of several to several hundred nanometers formed on its surface can be used. Also, a wide bandgap semiconductor substrate such as silicon carbide (SiC), gallium nitride (GaN), or gallium oxide (Ga2O3) can be used. The substrate 110 can also be doped with a dopant.

[0028] The photosensitive layer 120 is a layer that reacts by generating an electrical change when an optical signal is applied, and may include a two-dimensional semiconductor material. The photosensitive layer 120 can be easily used as a photosensitive layer of an optical gate device that can react to optical signals including near-infrared, visible light, and ultraviolet wavelengths.

[0029] Specifically, a two-dimensional (2D) semiconductor material may have a structure in which strong covalent bonds are formed within a single layer and layers are bonded by relatively weak van der Waals forces. Unlike conventional photoelectric conversion devices, the 2D semiconductor material has the advantage that a single material can be readily used as a photosensitive layer of a photoelectric conversion device by utilizing this direct transition property, thereby simplifying the device structure.

[0030] The two-dimensional semiconductor material may be arranged in the form of a plate-like sheet, for example, a flake, having a layered structure within the photosensitive layer 120, or may be in the form of a monolayer or a multilayer. The two-dimensional semiconductor material exhibits indirect transition characteristics in a bulk or thin film state of normal thickness, but exhibits direct transition characteristics when it is a single layer or a few layers thick. It has excellent photoresponsiveness, transparency, and flexibility, making it effectively applicable to optoelectronic devices.

[0031] In addition, the 2D semiconductor material has a layered structure in which each layer has very strong covalent bonds between the constituent atoms, and the layers are bound together by weak van der Waals forces. Since there are no dangling bonds extending outside the layers and, in principle, there is only two-dimensional interaction between the constituent atoms, carrier transport exhibits elastic transport, unlike conventional thin films or bulk materials. This makes it applicable as a high-mobility, high-speed, low-power semiconductor.

[0032] Furthermore, the two-dimensional semiconductor material has the advantage of being able to perform optoelectronic reactions sensitive to minute optical stimuli due to its atomic-scale thin layer structure, and therefore can realize learning ability with increased conductivity due to sensitive response to the application of pulsed optical stimuli and forgetting characteristics due to electrical stimuli.

[0033] The two-dimensional semiconductor material may include a transition metal dichalcogenide (TMD). Specifically, the transition metal dichalcogenide may be represented by the general formula MX2, where M is a transition metal element, such as Mo, W, Nb, V, Ta, Ti, Zr, Hf, Tc, Re, Ru, Co, Pd, Pt, Cu, Ga, In, Sn, Ge, Pb, or a combination thereof, and X is a chalcogen element, such as S, Se, Te, or a combination thereof. Specifically, the transition metal dichalcogenide material may include at least one selected from MoS2, MoSe2, MoTe2, WS2, WSe2, WTe2, ZrS2, ZrSe2, HfS2, HfSe2, NbSe2, ReSe2, PdTe2, or a combination thereof. More specifically, the transition metal dichalcogenide material may include MoS2, MoSe2, WS2, WSe2, or at least one selected from these, and in one embodiment, may include WSe2, but is not limited thereto.

[0034] The crystal structure of the two-dimensional semiconductor material has a covalent bond between the transition metal M and the chalcogen element X, and based on this, it can have a hexagonal structure in the planar direction. The crystal structure can be changed by performing a further phase change step or doping step.

[0035] In particular, when the two-dimensional semiconductor material is provided as a transition metal dichalcogenide sheet, e.g., a transition metal dichalcogenide flake, the average lateral length of which is on the scale of several to several hundred micrometers, e.g., a transition metal dichalcogenide microflake, is understood to be a transition metal dichalcogenide sheet. Specifically, the average lateral length of the transition metal dichalcogenide flake may be 10 to 100 μm, and in one embodiment, 50 to 60 μm, but is not limited thereto.

[0036] The electrode 130 may include a metal or a metal compound. The metal or metal compound may include at least one metal element selected from the group consisting of Ti, Ni, Au, Ag, and combinations thereof, and may be any metal or metal compound suitable for use in electronic devices such as metal electrodes and metal interconnections.

[0037] Method for producing transition metal dichalcogenide flakes FIG. 2 is a schematic diagram of a furnace used to produce transition metal dichalcogenide flakes using a molten salt assisted thermal chemical vapor deposition (SA-CVD) method according to one embodiment of the present invention.

[0038] 2, a manufacturing method of transition metal dichalcogenide flakes used as a photosensitive layer of an optical gate device according to an embodiment of the present invention using a molten-salt-assisted thermal chemical vapor deposition method may first include the step of preparing a first heating furnace and a second heating furnace spaced apart from each other within the same space. The first heating furnace and the second heating furnace are connected by a quartz tube, and a carrier gas can flow through both ends of the first heating furnace and the second heating furnace.

[0039] A first precursor containing a chalcogen material may then be placed in the first furnace.

[0040] The first precursor may be a chalcogen material, and may include, for example, at least one selected from S, Se, Te, or a combination thereof. In one embodiment, the first precursor may be Se, but is not limited thereto.

[0041] Also, a second precursor may be positioned in the second heating furnace at a certain distance from the first precursor, and a substrate may be positioned adjacent to the second precursor.

[0042] The second precursor may be positioned in the same space as the first precursor, but spaced a certain distance apart. The distance is a distance at which the precursor can be vaporized and transported in a vapor state in a heating furnace, and may be, specifically, 1 to 100 cm, more specifically, 10 to 70 cm, 20 to 60 cm, or in one embodiment, 20 to 40 cm, but is not limited thereto.

[0043] The second precursor may be a mixture containing the transition metal oxide and a metal halide salt.

[0044] The transition metal oxide is a compound in which a transition metal (M) represented by the above-mentioned transition metal dichalcogenide substance (general formula MX2) is bonded to an oxygen atom, and for example, x O y (where x and y are integers). Specifically, the transition metal oxide may refer to Mo, W, Nb, V, Ta, Ti, Zr, Hf, Tc, Re, Ru, Co, Pd, Pt, Cu, Ga, In, Sn, Ge, Pb, or an oxide of at least one selected from these. For example, the transition metal oxide may be MoO, MoO2, MoO3, MoO x , Mo2O3, Mo2O5, WO, WO2, WO3, WO x , W2O3, W2O5, W 18 O 49 , W 20 O 58 , W 24 O 70 , W 25 O 73 , W 40 O 118, NbO, NbO2, Nb2O3, Nb2O5, VO, VO2, V2O3, V2O5, Ta2O, Ta2O5, TiO2, ZrO, ZrO2, Zr2O3, Zr2O5, HfO2, Hf2O3, Hf2O5, etc. In one embodiment, the transition metal oxide may be WO3, but is not limited thereto.

[0045] The metal halide salt acts as a catalyst to promote the synthesis of the precursor. By adjusting the ratio of the precursor mixed with the metal halide salt, the shape and quality of the grown material, specifically, the nucleus density, crystal size, shape, and uniformity, can be controlled. Specifically, when the metal halide salt is applied to a thermal chemical vapor deposition (TCCVD) method, it can increase the vapor pressure, thereby improving the reaction kinetics of the material to be synthesized. More specifically, the metal halide salt can react with the transition metal oxide to form a highly volatile molten salt with a low melting point and high vapor pressure. A molten salt-assisted TCCVD method can also be performed. Therefore, by using a molten salt-assisted TCCVD method with the metal halide salt, high-quality transition metal dichalcogenide flakes can be grown at lower pressures and temperatures than conventional TCCVD methods using only a transition metal oxide as a precursor.

[0046] The metal halide salt may be represented by the general formula AZ or AZ2, where A is an alkali metal or alkaline earth metal, and Z is a halogen element. For example, the metal halide salt may include at least one selected from NaCl, NaBr, KCl, KBr, LiCl, LiBr, CaCl2, MgCl2, CaBr2, MgBr2, and combinations thereof. In one embodiment, the metal halide salt may be NaCl, but is not limited thereto.

[0047] A thermal chemical vapor deposition method using a molten salt formed by mixing the transition metal oxide and the metal halide salt, as described below, can lower the growth temperature of the transition metal dichalcogenide by promoting the reduction of the transition metal oxide. The mixing ratio of the transition metal oxide and the metal halide salt may be 4:1 to 8:1 by weight, specifically 5:1 to 7:1 by weight. When the mixing ratio is within this range, the average lateral length of the transition metal dichalcogenide flakes formed by the preferred manufacturing method of the present invention can grow to a large size, for example, approximately 50 to 60 μm, on the order of several to several tens of micrometers. This may result in the transition metal dichalcogenide flakes growing to a larger and more uniform size than a growth method that does not involve the mixing of the metal halide salt. However, if the mixing ratio of the metal halide salt relative to the transition metal oxide is increased beyond this range, the size of the resulting transition metal dichalcogenide flakes can decrease. In one embodiment, the mixing ratio of the transition metal oxide and the metal halide salt may be 6:1 by weight, but is not limited thereto.

[0048] Then, a step of forming a photosensitive layer including transition metal dichalcogenide flakes on the substrate by thermal chemical vapor deposition in the first furnace and the second furnace at different temperatures may be performed.

[0049] During the thermal chemical vapor deposition process, a molten salt may be formed as an intermediate by the reaction between the metal halide salt and the transition metal oxide. The molten salt can lower the growth temperature of the transition metal dichalcogenide by promoting the reduction of the transition metal oxide. The molten salt formed at this time is represented by the general formula A a M b O c(where a, b, and c are integers). The molten salt may be an intermediate substance that can be completely reacted and removed, and may not remain after the growth of the transition metal dichalcogenide flakes as the final substance is completed. Without the assistance of the molten salt, the synthesis of the transition metal dichalcogenide may not proceed smoothly. The mechanism by which the transition metal dichalcogenide flakes are formed using the thermal chemical vapor deposition method with the assistance of the molten salt can be explained, for example, by the following Reaction Schemes 1 to 3. <Reaction Scheme 1> 2WO 3(s) +2NaCl (s) →WO2Cl 2(g) +Na2WO 4(l) ……1 <Reaction Scheme 2> Na2WO 4(l) +2H2Se (g) +H 2(g) →WSe 2(s) +3H2O (g) +Na2O (s) ...2 <Reaction Scheme 3> WO2Cl 2(ads) +2H2Se (ads) +H 2(g) →WSe 2(s) +2H2O (g) +2HCl (g) ...3

[0050] First, the metal halide salt NaCl reacts with the transition metal oxide WO to form the gaseous WOCl. At the same time, it can form the molten salt NaWO, which has a low melting point and high vapor pressure. The molten salt NaWO is a highly volatile material and can react with HSe, a chalcogen vapor saturated in a gaseous state in a heating furnace, to form the transition metal dichalcogenide WSe. WSe can also be formed by the reaction of WOCl with HSe. The inclusion of the metal halide salt allows for faster growth of high-quality transition metal dichalcogenide flakes at lower pressures and temperatures than chemical vapor deposition methods using only transition metal oxides as precursors.

[0051] The growth temperature in the thermal chemical vapor deposition process governs the deposition process, crystal nucleation, and growth rate of the material, and may directly affect the kinetics of the synthesized material, which may affect the coverage of the thin film layer. The heating temperature of the first furnace containing the first precursor containing the chalcogen material may be 500°C or higher and lower than 700°C, and in one embodiment, may be 600°C, but is not limited thereto. The temperature of the second furnace containing the second precursor containing a mixture of a transition metal oxide and a metal halide salt may be 700°C or higher and lower than 900°C, and in one embodiment, may be 800°C, but is not limited thereto.

[0052] The transition metal dichalcogenide flakes formed by thermal chemical vapor deposition by heating the first and second heating furnaces can be deposited on the substrate, and the deposition time is a factor that can change the coverage of the thin film layer. As the deposition time increases, the coverage of the substrate can increase. The deposition time may be 1 to 10 minutes, specifically 3 to 9 minutes, and more specifically 5 to 8 minutes. When the thermal chemical vapor deposition process is performed within this range, 80% or more of the substrate area can be covered. In one embodiment, the deposition time of the thermal chemical vapor deposition process may be 7 minutes, and the transition metal dichalcogenide flakes produced thereby can have 90% or more of the substrate area covered.

[0053] In particular, by using the molten salt-assisted thermal chemical vapor deposition method of the present invention, it is possible to lower the growth temperature by promoting the reduction of transition metal oxides with molten salts.In addition, transition metal dichalcogenide flakes can simultaneously realize electrostatic gating using a dielectric and optical gating by applying an optical signal, which has the advantage of combining different gating methods to realize AND and OR logic operations in a single device.

[0054] A step of depositing electrodes onto the photosensitive layer to form at least two or more contact sites may then be performed.

[0055] The electrode may include a metal or a metal compound. The metal or metal compound may include at least one metal element selected from the group consisting of Ti, Ni, Au, Ag, and combinations thereof, and may be any metal or metal compound suitable for use in electronic devices such as metal electrodes and metal interconnections.

[0056] The step of depositing the electrode can be performed using, but is not limited to, a metal thin film deposition method that applies energy at a level that does not induce defects in the photosensitive layer, such as an electron beam evaporator, a thermal evaporator, or sputtering.

[0057] The present invention will be described in more detail below with reference to examples and comparative examples. However, the following examples and comparative examples are for illustrative purposes only and do not limit the scope of the present invention.

[0058] Preparation Example 1: WSe using molten salt-assisted thermal chemical vapor deposition (SA-CVD) method 2 Layer Growth A quartz boat containing 48 mg of selenium (Se, >99.5%) powder was placed in the primary furnace, and a quartz boat containing a mixture of 24 mg of tungsten trioxide (WO3, 99.9%) powder and 4 mg of sodium chloride (NaCl, >99.0%) powder was placed in the secondary furnace. Meanwhile, a 2.5 cm x 2.5 cm silicon wafer with a 300 nm thick SiO2 insulating layer was placed in the secondary furnace containing the WO3 / NaCl mixture. The spacing between the two quartz boats was optimized to 34 cm within the quartz tube, which was 10 -2 After evacuating to Torr, Ar was introduced as a carrier gas at 100 sccm. The primary and secondary furnaces were then heated at ramp rates of 10.9 °C / min and 14.5 °C / min, respectively. WSe2 was grown under conditions where the primary furnace containing Se was heated to 600 °C and the secondary furnace containing WO3 / NaCl was heated to 800 °C. During the WSe2 growth process, Ar was continuously introduced at a flow rate of 100 sccm and H2 at 20 sccm, maintaining the flow rate for 7 minutes. After the reaction was completed and the furnaces were cooled, a wafer substrate on which multiple WSe2 flakes were grown was obtained using molten salt-assisted thermal chemical vapor deposition (MSCCVD).

[0059] Preparation Example 2: WSe using thermal chemical vapor deposition (CVD) method 2 Layer Growth A wafer substrate on which WSe flakes were grown was obtained in the same manner as in Production Example 1, except that instead of using a mixed powder of tungsten trioxide (WO) powder and sodium chloride (NaCl), sodium chloride (NaCl) was omitted and only tungsten trioxide (WO) powder was used.

[0060] Experimental Example 1: Characterization of transition metal dichalcogenide flakes grown by molten salt assisted thermal chemical vapor deposition method FIG. 3 shows (a) an optical photograph of a substrate on which transition metal dichalcogenide flakes have been grown by a molten-salt-assisted thermal chemical vapor deposition method according to Preparation Example 1 of the present invention, (b) an optical microscope image thereof, (c) coverage (%) over time of thermal chemical vapor deposition, and (d) X-ray photoelectron spectroscopy (XPS) results of the transition metal dichalcogenide flakes grown by thermal chemical vapor deposition. FIG. 4 shows (a) an atomic force microscopy (AFM) result of the transition metal dichalcogenide flakes according to Example 1 of the present invention, (c) a height profile thereof, and (b) a Kelvin probe force microscope (KPFM) image and a contact potential difference (CPD) profile thereof.

[0061] Referring to Figures 3 and 4, it can be seen that the transition metal dichalcogenide flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method grew uniformly on the SiO2 / Si substrate. When the heating temperature of the second furnace containing the second precursor, a mixture of transition metal oxide and metal halide salt, was 800°C and the deposition time was 7 minutes, a very high coverage of approximately 95% was observed. This result demonstrates that the transition metal dichalcogenide material maintained its 2H phase while achieving high coverage. Furthermore, it can be seen that the transition metal dichalcogenide flakes produced had smooth, non-rough surfaces and a uniform thickness throughout the entire flake. Profile scans confirmed that the single-layer transition metal dichalcogenide flakes were approximately 0.7 nm thick. Furthermore, the bilayer, trilayer, and multilayer transition metal dichalcogenide flakes were formed to thicknesses of 1.5 nm, 2.2 nm, and 6.5 nm, respectively. Furthermore, the work function difference between the single layer of transition metal dichalcogenide flakes and the Si / SiO2 substrate was approximately 0.1V.

[0062] FIG. 5 shows Raman analysis of (a) single-layer (1L), double-layer (2L), triple-layer (3L), and multi-layer (Multi-L) transition metal dichalcogenide flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method according to Preparation Example 1 of the present invention; and (b) E 1 2g Vibration mode (251cm -1 (c) Raman intensity mapping of the transition metal dichalcogenide flakes at different layer numbers; (d) PL intensity mapping of the single-layer transition metal dichalcogenide flakes on a SiO2 substrate.

[0063] 5a and 5b, Raman analysis was performed on the transition metal dichalcogenide (WSe2) flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method, and the crystal structure of the 2H phase was confirmed. The Raman spectrum showed that the in-plane vibrational mode (E 1 2g ) and out-of-plane vibration modes (A 1g ) equivalent to approximately 250 cm -1 and 260cm -1 On the other hand, the interlayer interaction mode (B 2g 1 ) at approximately 304 cm -1 A peak was observed at approximately 304 cm in the single-layer (denoted as 1L) sample. -1 Although no peak is observed at E, it can be seen that the peak is confirmed for the multilayer (denoted as 2L, 3L, and Multi-L) samples. 1 2g Vibration mode (251cm -1) Raman intensity mapping for a monolayer WSe2 flake confirms that the Raman intensity is uniformly distributed over the entire area of ​​the transition metal dichalcogenide flake.

[0064] 5c and 5d, the photoluminescence (PL) results show that the transition metal dichalcogenide monolayer peak exhibits high intensity, while the multilayer (bilayer and multilayer) peaks exhibit a decrease in peak intensity as the number of layers increases. PL mapping of a 0.7 nm monolayer of transition metal dichalcogenide (WSe) on a SiO substrate shows a uniform intensity.

[0065] FIG. 6 shows (a) a high-resolution transmission electron microscope (HRTEM) image of a SiO / WSe / Pt cross-sectional layer of transition metal dichalcogenide flakes synthesized by the molten-salt-assisted thermal chemical vapor deposition method according to Preparation Example 1 of the present invention, and (b) an energy dispersive X-ray spectroscopy (EDS) image of the same.

[0066] Referring to FIG. 6, it can be seen that the thickness of WSe2 grown on the SiO2 substrate by the molten salt-assisted thermal chemical vapor deposition method of the present invention is about 3 nm. It can also be seen that the thin film is formed from a two-dimensional material into a uniform and flat thin film, and no impurities are detected by TEM-EDS elemental mapping analysis.

[0067] FIG. 7 shows optical photographs of transition metal dichalcogenide flakes synthesized using a 2×2 inch substrate by the molten salt-assisted thermal chemical vapor deposition method according to Preparation Example 1 of the present invention, and 25 locations used for photoluminescence (PL) measurements. FIG. 8 shows (a) in-plane vibration mode (E) measurements collected at 25 locations within the substrate on which the transition metal dichalcogenide flakes synthesized using a 2×2 inch substrate by the molten salt-assisted thermal chemical vapor deposition method according to Preparation Example 1 were grown. 1 2g ) and out-of-plane vibration modes (A 1g ) equivalent to approximately 250 cm -1 and 260cm -1 (a) Raman results and (b) photoluminescence (PL) results of the SiO2 substrate (1.62 eV).

[0068] Referring to Figures 7 and 8, it can be seen that the transition metal dichalcogenide flakes synthesized by the molten salt assisted thermal chemical vapor deposition method exhibited uniform Raman and photoluminescence analysis results consistent with WSe2 at all 25 locations within the grown substrate, confirming that even using a large 2x2 inch substrate, it is possible to grow transition metal dichalcogenide flakes with uniform quality and characteristics across the entire area of ​​the substrate.

[0069] Example 1: WSe prepared using the molten salt-assisted thermal chemical vapor deposition (SA-CVD) method 2 Optical gate device containing flakes as a photosensitive layer The wafer substrate on which the WSe2 layer was grown by the method of Preparation Example 1 was used as a photosensitive layer, and then 50 nm of nickel (Ni) was deposited on the substrate using an e-beam evaporator to form a metal electrode. This resulted in the formation of multiple electrode layers, i.e., WSe2 / Ni interfaces, that were spaced apart from each other and stacked on the WSe2, and an optical gate device was fabricated that included WSe2 flakes fabricated by the molten salt-assisted thermal chemical vapor deposition (SA-CVD) method as a photosensitive layer.

[0070] Experimental example 2: Measurement of electrical characteristics of elements The electrical properties of the optical gate device containing the transition metal dichalcogenide flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method of the present invention as a photosensitive layer were measured using a probe system (4200A-SCs, Keithley Instruments) semiconductor parameter analyzer in a darkroom under ambient conditions. Raman spectra were obtained at room temperature under ambient pressure using a Raman spectrometer (DXR2xi, Thermo Fisher Scientific) with a 532 nm laser and 6.1 mW incident laser power, and the Raman spectra were measured from 50 to 3500 cm. -1 Spectra were obtained over a range of 30 μm x 30 μm. Optically gated and Kelvin probe images of the topography were collected using an atomic force microscope (MFD-3D Origin™ AFM, Oxford Instruments) in non-contact and scanning Kelvin probe microscopy (SKPM) modes. Fourier transform infrared (FT-IR) spectra were obtained at room temperature using a FT-IR spectrophotometer (Nicolet™ iS50, Thermo Fisher Scientific). X-ray photoelectron spectroscopy (XPS) analysis was performed using a Thermo Scientific™ Nexsa™ G2 surface analysis system. The spectrometer used for photoluminescence was a PL (Nanobase) instrument obtained at room temperature, and the cross-sectional height profile was measured using a Themis-Z (trademark) TEM (transmission electron microscope) instrument manufactured by FEI.

[0071] FIG. 9 shows (a) a schematic diagram and a circuit diagram of an optical gate device including a photosensitive layer of transition metal dichalcogenide flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention, used as a conventional back-gated transition metal dichalcogenide field-effect transistor (back-gated FET), and (b) a constant V DS (1V) V BG(c) p-type transmission characteristics measured by swiping (-50V to +50V) and (d) output IV results when swiping from -10V to +10V at different gate biases.

[0072] FIG. 10 shows (a) a schematic diagram and a circuit diagram of an optical gate device including a photosensitive layer of transition metal dichalcogenide flakes synthesized by the molten-salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention, when optical power of 405 nm wavelength is applied to the device; (b) transmission characteristics under different optical gate powers; and (c) V characteristics from −10 V to +10 V under threshold optical powers. DS The output IV results under different optical gate powers ranging from 0.2 to 1.0 mW under swipe.

[0073] 9 and 10, it can be seen that the optical gate device including the transition metal dichalcogenide flakes synthesized by the molten salt assisted thermal chemical vapor deposition method according to the first embodiment of the present invention as a photosensitive layer can be driven in both FET and LGT modes during electrical gating and light gating. DS Back gate swipe at V = 1V BG The p-type transfer characteristics were measured in WSe2-based back-gated transistor devices using a voltage range from -50V to +50V. The FET devices were measured at a top gate voltage of 92.35cm. 2 V -1 s -1The photo-gated transistor exhibits p-type dominant driving characteristics and hole mobility with bipolar behavior. Referring to Figure 10, the same device can also be photogated using photoelectric power. By illuminating the photogate, photo-generated charge carriers can modulate the conductivity of the light-sensitive region, which in turn modulates the electrical behavior of the transistor. The output characteristics of the photo-gated transistor can be adjusted by the output current or voltage and the input light intensity, wavelength, or other related parameters. The photo-gated transistor exhibits high sensitivity and fast response time, and the photoelectric power of the other output can provide multiple "ON" states. Therefore, the device of the present invention can be used as an integrated device that can be driven by a device capable of both electrical signal processing and optical sensing.

[0074] FIG. 11 shows (a) the dynamic driving mode under pulse modulation of light irradiation at threshold light power of an optical gate device including a transition metal dichalcogenide flake as a photosensitive layer synthesized by the molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention, (b) the logic operation based on a single device that simultaneously inputs electrical gating and light gating, and (c) the brain-inspired synaptic function mode at threshold light power.

[0075] Referring to FIG. 11, an optical gating device (LGT) containing transition metal dichalcogenide flakes synthesized by the molten-salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention as a photosensitive layer can demonstrate the ability to induce photoresponsiveness and the generation of postsynaptic currents. Synaptic weights in LGTs are intricately connected to various parameters, including the power, duration, and frequency of the applied stimulus. Regarding power, it is important to exceed a certain threshold energy barrier for any transmission between different states to occur. This phenomenon is similar to that in biological neurons, where the signal strength must exceed a certain threshold to enable the formation of a synapse between successive axons. Similarly, in solid-state synaptic devices, regardless of whether the stimulus is electrical, optical, or chemical in nature, it must exhibit a strength above a threshold for effective actuation and state transitions. In the absence of optical stimulation, the device remains unresponsive and produces no observable output. However, when a relatively low intensity optical stimulus that falls below the threshold is applied, it triggers a carrier-based photoresponse, which, although detectable, is not sufficient to set significant synaptic weights. In contrast, when the intensity of the stimulus rises above the threshold barrier (P TH When the laser power level exceeds a certain threshold (denoted by ), a transformation occurs. The normal photoresponse evolves into a synaptic response characterized by non-zero synaptic weights. This transition signifies the device's ability to store and process information similar to short-term memory. In particular, when the laser power level varies within the range of 0.2-0.8 mW (see Figure 10 again), the LGT exhibits a synaptic weight of zero, exhibiting behavior consistent with sensory perception. However, when the laser stimulus intensity exceeds 1 mW, it completes with non-zero synaptic weights and undergoes a transition to a state similar to short-term memory in sensory behavior. This change in function is applicable to both photodetectors and electronic synaptic devices, particularly in the context of sensory memory systems, where the LGT excels in information processing and storage.

[0076] FIG. 12 shows the results of (a) 405 nm wavelength and 0.2 to 0.8 mW / cm 2 of an optical gate device including, as a photosensitive layer, transition metal dichalcogenide flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention. 2 (b) Dynamic photoresponse results generated at a laser source of power, (b) photoresponse results across the operating frequency spectrum ranging from 1.4 Hz to 0.1 Hz, and (c) response characteristics.

[0077] Referring to Figure 12, the light-induced dynamic driving characteristics of the WSe2 LGT were evaluated under both dark conditions and laser (405 nm) illumination. Figure 12a shows the temporal photoresponse across a range of optical source powers, from 0.2 mW to 0.8 mW, when the gate voltage was zero. The measured response remained consistent and reproducible for multiple consecutive ON / OFF cycles at each power level. Such stability and repeatability demonstrate the robust performance of the LGT dynamic response, further highlighting its high sensitivity. Furthermore, the LGT exhibits excellent photoresponse across the optical operating frequency spectrum, ranging from a high of 1.4 Hz to a low of 0.1 Hz. The remarkable photodetection performance observed at various power levels and frequencies indicates its suitability for various optical communication devices. The rise time for each optical signal frequency was approximately 60 ms, while the decay time was approximately 50 ms, demonstrating fast response characteristics. This demonstrates the excellent performance of the LGT-based photodetector, characterized by high sensitivity, cycling stability, and applicability across the optical operating frequency range. These attributes make them applicable to a variety of optical communication and sensing devices.

[0078] FIG. 13 shows (a) the response of an optical gate device containing transition metal dichalcogenide flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention as a photosensitive layer, and (b) the specific detectability analysis for each bias across the channel.

[0079] Referring to Figure 13, responsivity (R) is an important parameter that quantifies the sensitivity of a detector to incident optical power. The optical power (P O ) versus the amount of photocurrent (I ph ) is precisely calculated as a ratio of the photodetector's responsivity (R) and non-detectability (D). This parameter is a fundamental measure that provides valuable insight into the performance characteristics of a photodetector that converts incident photons into electrical current. * Detectivity) is a parameter for evaluating the photodetector performance of an LGT device, and can be expressed by the following Equations 1 and 2:

[0080]

number

[0081]

number

[0082] where λ is the wavelength, q is the charge of the electron, h is Planck's constant, c is the speed of light in a vacuum, and D * is the degree of non-detection, and J dark is the dark current density.

[0083] In terms of responsivity and detectability, the optical gate element of the present invention is highest when an optical power source of 0.2 mW is used, with the respective values ​​being responsivity of approximately 40 μA / W and detectability of approximately 3.16×10 9 cmHz 0.5 W -1However, this performance metric appears to decrease as the optical power increases above this threshold value. This decrease in responsivity and non-detectability indicates the presence of specific trap states within the optical gate element. Such deviations from ideal operation indicate the presence of non-ideal characteristics of the optical gate element, such as trap states and limited charge carrier extraction.

[0084] FIG. 14 is an analysis of a transistor logic using an optical gate device containing, as a photosensitive layer, transition metal dichalcogenide flakes synthesized by the molten salt assisted thermal chemical vapor deposition method according to Example 1 of the present invention.

[0085] Referring to FIG. 14a, a series of inputs can be demonstrated using a 5mW optical gate as IN-1 and a +5V electrical gate as IN-2, resulting in an AND logic output. Referring to FIG. 14b, a series output can be demonstrated using a 5mW optical gate as IN-1 and a -5V electrical gate as IN-2, resulting in an OR logic output. Referring to FIGS. 14c and 14d, the LGT and amplifier response can be output as a summation operation, where the single A and B responses are summed to generate A+B. Here, a 5mW laser optical gate was used as IN-A and a 1mW LED gate was used as IN-B. The input data is displayed in black / blue, and the output logic function of the device is displayed in red.

[0086] FIG. 15 shows (a) excitatory postsynaptic behavior as a function of the number of pulses under a positive bias of the back gate electric field, (b) inhibitory postsynaptic behavior as a function of the number of pulses under a negative bias of the back gate electric field, and (c) optimized excitatory postsynaptic current (EPSC) and inhibitory postsynaptic current (IPSC) characteristics when the gated bias field for efficient power consumption is not small, for an optical gate device including a photosensitive layer of transition metal dichalcogenide flakes synthesized by the molten salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention.

[0087] 15a to 15c, the synaptic characteristics of the optical gate device can be confirmed by applying a 405 nm wavelength laser stimulus with a power of 1 mW operating at a source frequency of 1 Hz when the laser gating power exceeds the threshold voltage. DS ) was held at a constant value of 1.0 V, whereas the back gate voltage (V BG ) was varied across 10, 20, and 30 V for excitatory postsynaptic currents (EPSCs). For inhibitory postsynaptic currents (IPSCs), V BGwas adjusted to -10V, -20V, and -30V. Due to the p-type semiconductor properties of the WSe2-based photosensitive layer, the transmission strength of the gating weight value decreases as the back gate potential increases. It can be confirmed that the optical gating device including the transition metal dichalcogenide flakes according to the present invention as a photosensitive layer exhibits a gradual progression of EPSC and IPSC behavior, according to the learning (Fig. 15a) and forgetting (Fig. 15b) dynamics based on pulse stimulation, which are affected by both the polarity and magnitude of the back gate field. In particular, the larger the back gate field, the earlier the gating responses to both EPSC and IPSC are saturated. Therefore, the optical gating device including the transition metal dichalcogenide flakes according to the present invention as a photosensitive layer exhibits the ability to exhibit learning behavior even in the absence of a back gate field, as shown in Fig. 15c. BG = -5V, so V BG It can be adjusted to display very small negative polarity forgetting behavior applied to V. BG At = 0 V, a conductance state in the optical range is observed, extending until saturation is reached. This suggests that the device can be operated efficiently at even lower power levels, driven by synaptic activity with reduced energy consumption.

[0088] FIG. 16 shows (a) the EPSC and IPSC characteristics as a function of pulse duration for an optical gate element including, as a photosensitive layer, transition metal dichalcogenide flakes synthesized by the molten-salt-assisted thermal chemical vapor deposition method according to Example 1 of the present invention, and (b) the paired pulse facilitation (PPF: Paired Pulse Facilitation, a phenomenon in which, when a presynaptic cell is stimulated consecutively, the second synaptic transmission is facilitated compared to the first synaptic transmission) and paired pulse depression (PPD: Paired Pulse Depression, a phenomenon in which, when a presynaptic cell is stimulated consecutively, the second synaptic transmission is depressed compared to the first synaptic transmission) characteristics of the optical gate element.

[0089] Referring to Figures 16 and 17, the excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic currents (IPSCs) induced by pulsed laser stimulation were measured at constant back gate voltages (V) of 10 V and -10 V, respectively. BG ), and it can be seen that as the laser pulse duration increases from 50 ms to 550 ms, the EPSC and IPSC responses show a gradual tendency toward saturation. This behavior is similar to the mechanisms of paired pulse facilitation (PPF) and paired pulse depression (PPD) observed in biological neurons, which play an important role in information processing within neuronal networks. In particular, it can be seen that the EPSC induced in response to the second laser pulse is even larger than that induced by the first pulse, and conversely, the IPSC response to the second laser pulse is reduced compared to that of the first laser pulse. These results are consistent with the characteristics known as synaptic responses in biological systems and should be understood as demonstrating compatibility with synaptic properties and functions.

[0090] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it should be understood by those skilled in the art that the present invention can be embodied in other specific forms without changing the technical concept or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are merely illustrative in all respects and are not limiting. [Explanation of symbols]

[0091] 100 Optical gate element 110 Substrate 111 Silicon 112 Insulating layer 120 Photosensitive layer 130 electrodes

Claims

1. In a method for manufacturing an optical gate element, providing a first heating furnace and a second heating furnace spaced apart from each other in the same space; A first precursor containing a chalcogen material is placed in the first heating furnace, and tungsten trioxide (WO ) as a transition metal oxide is placed in the second heating furnace. ３ a second precursor containing a mixture of ZnO (ZnO) and sodium chloride (NaCl) as a metal halide salt, and placing a substrate adjacent to the second precursor; heating the first furnace and the second furnace to different temperatures, respectively, and performing molten salt assisted thermal chemical vapor deposition to form a photosensitive layer including at least one transition metal dichalcogenide flake on the substrate; depositing source and drain electrodes on the photosensitive layer to form at least two contact sites; forming a gate electrode below the substrate; Including, The mixing ratio of the transition metal oxide and the metal halide salt is 5:1 to 7:1 by weight, A method for manufacturing an optical gate element, wherein the element is a logic element that derives current characteristics from a combination of optical power applied in pulses from the outside to the photosensitive layer and a positive or negative voltage applied to the gate electrode and performs AND or OR logical operations.

2. In the step of forming the photosensitive layer, the temperature of the first heating furnace is equal to or higher than 500°C and lower than 700°C; 2. The method for manufacturing an optical gate element according to claim 1, wherein the temperature of the second heating furnace is 700°C or higher and lower than 900°C.

3. The method for manufacturing an optical gate element according to claim 1 , wherein the transition metal dichalcogenide flakes are in the form of a single layer or two or more layers.

4. 2. The method for manufacturing an optical gate element according to claim 1, wherein the transition metal dichalcogenide flakes contained in the photosensitive layer have an average horizontal length of 10 to 100 μm.

5. the source electrode and the drain electrode comprise a metal or a metal compound; The method for manufacturing an optical gate element according to claim 1 , wherein the metal or metal compound contains at least one metal element selected from the group consisting of Ti, Ni, Au, Ag, and combinations thereof.

6. In the optical gate element, a photosensitive layer disposed on a substrate, the photosensitive layer including at least one transition metal dichalcogenide flake, and the photosensitive layer being manufactured by the manufacturing method according to any one of claims 1 and 2 to 5; a source electrode and a drain electrode disposed on the photosensitive layer and spaced apart from each other; a gate electrode disposed below the substrate; Equipped with The element is an optical gate element, which is a logic element that derives current characteristics from the combination of optical power applied in pulses from the outside to the photosensitive layer and a positive or negative voltage applied to the gate electrode, and performs AND or OR logical operations.

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