A two-dimensional Cu x Fe y Te crystal thin film and a method for preparing the same

Abstract

The application provides a two-dimensional Cu x Fe y Te crystal thin film and a preparation method thereof, and the method comprises the following steps: S1, selecting Cu, Fe and Te precursors, and pretreating a substrate; S2, mixing Cu and Fe, placing the mixed Cu and Fe in a first carrier, placing the Te precursor in a second carrier, and respectively arranging the first carrier, the second carrier and the substrate in corresponding areas of a CVD reaction device; S3, performing airtightness detection and carrier gas treatment on the CVD reaction device, and heating under the carrier gas condition to make the precursors sublimate and transport; S4, performing heat preservation growth under a preset temperature and the carrier gas condition to make the sublimated precursors react and deposit on the surface of the substrate; and S5, after the growth is completed, cooling the CVD reaction device to room temperature under an inert atmosphere, and obtaining a two-dimensional Cu x Fe y Te crystal thin film. Through regulation and control of the use amount ratio of the Cu, Fe and Te precursors and process parameters, the application realizes the synergistic transport and controllable deposition of the multi-element precursors, and prepares the two-dimensional Cu x Fe y Te crystal thin film with adjustable Cu / Fe element ratio and good crystallization quality.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional material preparation technology, and particularly to a two-dimensional Cu x Fe y Te crystalline thin films and their preparation methods. Background Technology

[0002] Two-dimensional magnetic materials, possessing atomic-level thickness, tunable electronic structure, and magnetic order, provide an important material platform for studying low-dimensional spin transport, magnetic anisotropy, interlayer coupling, and related quantum effects. In recent years, two-dimensional magnetic materials and two-dimensional transition metal chalcogenides have attracted widespread attention, showing potential applications in spintronics, optoelectronics, information storage, sensing, and energy conversion. However, currently reported two-dimensional magnetic systems still suffer from limitations such as a limited variety of materials, relatively concentrated structural types, and insufficient space for compositional control. Therefore, developing novel two-dimensional magnetic material systems with tunable composition, stable structure, and controllable fabrication capabilities is of great significance for enriching the family of two-dimensional magnetic materials and expanding their functional applications.

[0003] Two-dimensional Cu x Fe y Te, as a low-dimensional ternary transition metal telluride system, possesses both tunable site occupancy of transition metal elements and potential magnetoelectric coupling characteristics, promising unique properties in low-dimensional magnetism, photoelectric response, and multi-field modulation. Compared with traditional binary chalcogenides, the synergistic introduction of Cu and Fe elements provides more degrees of freedom for adjusting lattice structure, carrier concentration, magnetic exchange interaction, and band structure, thus enabling the construction of continuously tunable two-dimensional magnetic materials or magnetic thin films. These materials can serve not only as model systems for studying low-dimensional magnetic ordering, interlayer coupling, and spin-related effects, but also as candidate materials for developing novel photoelectric detectors, nonlinear optical modulation, and spintronic devices.

[0004] In optoelectronic applications, two-dimensional Cu x Fe y Te, with its strong light absorption and ultrathin thickness, holds promise for applications in photoelectric detection, optical modulation, optical limiting, and integrated photonic devices. By controlling the Cu / Fe ratio, film thickness, and crystallinity, its band structure, interfacial charge transport behavior, and photoresponse characteristics can be further altered, making it suitable for constructing heterostructures with MoS2, WS2, graphene, and other two-dimensional materials. This expands its potential applications in broadband photoelectric detection, interfacial charge modulation, and integrated optoelectronic devices. Simultaneously, the large specific surface area and short carrier transport paths of two-dimensional thin film materials provide a foundation for further applications in catalysis, sensing, and energy conversion.

[0005] In the fields of spintronics and low-dimensional magnetic devices, two-dimensional Cux Fe y In the Te system, the Fe-related magnetic moment, Cu modulation effect, and the strong spin-orbit coupling introduced by Te may collectively influence the material's magnetic anisotropy, magnetic phase transition behavior, and spin transport properties. Through compositional adjustment and layer number control, it is hoped that synergistic regulation of magnetic exchange interactions, electronic structure, and magnetic response behavior can be achieved, providing a new material platform for studying magnetic phase transitions, spin correlations, magnetoelectric coupling, and interface modulation effects in low-dimensional magnetic systems. These materials can also be combined with other two-dimensional magnetic, semiconductor, or conductive two-dimensional materials to form heterostructures, allowing for the exploration of the modulation mechanisms of low-dimensional magnetism by electric fields, optical fields, strain, or interfaces.

[0006] Currently, the preparation of low-dimensional materials related to ternary transition metal tellurides still mainly relies on methods such as mechanical exfoliation, solution methods, or chemical vapor transport. Mechanical exfoliation can typically obtain thin-layer samples with high crystallinity, but its yield is limited, the location is random, and the size and number of layers are difficult to control precisely, making it difficult to meet the requirements of subsequent device arraying and large-scale applications. Solution methods are relatively simple, but the products are prone to problems such as insufficient crystallinity, surface residues, uneven thickness distribution, and limited phase purity, which are not conducive to revealing the intrinsic properties of the material. Chemical vapor transport is more suitable for preparing bulk single crystals or thicker crystalline materials. Although it helps to obtain high-quality parent crystals, it is not ideal for directly preparing thin-layered, compositionally tunable, and well-continuous two-dimensional Cu. x Fe y Te crystal thin films still have significant limitations.

[0007] Chemical vapor deposition (CVD) is an important method for preparing high-quality two-dimensional materials. It offers advantages such as adjustable process window, high film purity, good substrate compatibility, and scalable growth, and has been widely used for the controllable preparation of various two-dimensional transition metal chalcogenides and some two-dimensional magnetic materials. However, for Cu… x Fe y For multi-component telluride systems like Te, CVD growth still faces significant challenges. On the one hand, the volatilization characteristics, transport behavior, and reactivity of Cu, Fe, and Te precursors differ significantly, easily leading to asynchronous gas phase supply and deviations in product composition. On the other hand, the adsorption, diffusion, and nucleation processes of multi-metal elements on the substrate surface are complex. If the temperature field, carrier gas flow rate, and precursor position are not properly controlled, problems such as impurity phase formation, uneven grain distribution, uncontrollable thickness, and insufficient film continuity can easily occur. In addition, excessively high or unstable growth temperatures may cause Te loss, structural distortion, or decreased substrate compatibility, thereby affecting film quality and performance repeatability.

[0008] Therefore, there is an urgent need to develop a CVD method that is relatively simple, has controllable parameters, good repeatability, and enables the controllable preparation of two-dimensional crystalline thin films by adjusting the Cu / Fe elemental ratio. By rationally designing the precursor ratio, source and growth region positions, carrier gas composition, growth temperature, and cooling process, it is hoped that the synergistic transport and reactive deposition behavior of multi-element precursors can be improved, the probability of impurity phase formation can be reduced, and the crystal quality, compositional uniformity, and layer thickness controllability of the thin film can be enhanced, thereby paving the way for the preparation of two-dimensional Cu... x Fe y This provides a reliable material basis for the preparation and performance study of Te crystalline thin films. Summary of the Invention

[0009] The technical problem to be solved by the present invention is: to provide a two-dimensional Cu x Fe y Te crystal thin films and their preparation methods solve the problems existing in the preparation of related two-dimensional ternary transition metal telluride thin films, such as difficulty in adjusting the Cu and Fe element ratio, unstable film crystal quality, insufficient thickness uniformity, and difficulty in controlling impurity phases.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a two-dimensional Cu x Fe y The preparation method of Te crystal thin film is as follows: S1. Select Cu, Fe, and Te as precursors. The molar ratio of Cu to Fe is x1:y1, and the molar amount of Te is greater than the sum of the molar amounts of Cu and Fe. Weigh each precursor and grind them into a uniform powder for later use. Select a substrate and pretreat it to ensure the surface roughness of the clean surface is ≤1 nm. Where x+y=1, 0.01≤x1 / y1≤0.5, and x1 / y1<x / y. S2. After uniformly mixing the Cu and Fe elements ground in step S1, place them in the first carrier and place the first carrier in the growth zone of the CVD reactor. Place the Te elements ground in step S1 in the second carrier and place the second carrier in the sublimation zone upstream of the first carrier. The distance between the first carrier and the second carrier is 20-30 cm. Place the pretreated substrate in step S1 in the thin film deposition zone above the growth zone, with the clean surface of the substrate facing the first carrier. In the horizontal plane, the distance between the projection of the substrate on the horizontal plane and the projection of the second carrier on the horizontal plane is 20-30 cm. The ratio of the distance between the clean surface of the substrate and the first carrier to the distance between the projection of the substrate on the horizontal plane and the projection of the second carrier on the horizontal plane is 1:(20-40). After S3 and S2 are completed, the airtightness of the CVD reactor is tested and the carrier gas is treated. After the carrier gas treatment is completed, the growth zone is heated to 700℃ to 900℃ at a heating rate of 10℃ / min to 30℃ / min, and the temperature of the sublimation zone is stabilized at 400℃ to 500℃. During the heating process, the first mixed carrier gas is introduced to form the precursor into a gaseous precursor and transported with the carrier gas. S4. After the growth zone and sublimation zone in step S3 reach the preset temperature and stabilize, the second mixed carrier gas is introduced to allow the gaseous precursor to react and deposit on the substrate surface, and the growth is maintained at this temperature for 20-30 minutes. After the film growth in step S5 and S4 is completed, heating is stopped, and an inert carrier gas is continuously introduced to cool the CVD reactor in the inert carrier gas atmosphere at a cooling rate of 10℃ / min to 50℃ / min until the CVD reactor temperature drops to room temperature, thus obtaining two-dimensional Cu. x Fe y Te crystalline thin films.

[0011] Preferably, x is 0.1 to 0.9 and y is 0.1 to 0.9.

[0012] Specifically, under different Cu / Fe feed molar ratios, the actual Cu / Fe elemental ratio in the final film exhibits a nonlinear relationship with the feed ratio. This phenomenon may be related to the differences in the volatilization, transport, adsorption, and surface diffusion behaviors of Cu and Fe precursors under high-temperature conditions. At lower Cu / Fe feed ratios, the relative enrichment of Cu during gas-phase transport and substrate surface adsorption may be more pronounced, resulting in a higher Cu elemental ratio in the final film compared to the feed ratio. As the Cu / Fe feed ratio further increases, the adsorption sites on the substrate surface, competitive adsorption of metal atoms, and the nucleation growth process collectively influence the proportion of Cu and Fe elements entering the crystalline film, making the relationship between the feed ratio and the final film elemental ratio not a simple linear one. Therefore, the Cu / Fe elemental ratio in the two-dimensional CuxFeyTe crystalline film can be directionally controlled by adjusting the Cu / Fe feed molar ratio.

[0013] Preferably, the molar amount of elemental Te is 1.2 to 1.5 times the sum of the molar amounts of elemental Cu and elemental Fe.

[0014] In one embodiment, in step S3, the first mixed carrier gas is a mixed gas flow of Ar and H2, with an Ar flow rate of 100-130 sccm and an H2 flow rate of 10-20 sccm; in step S4, the second mixed carrier gas is a mixed gas flow of Ar and H2, with an Ar flow rate of 50-100 sccm and an H2 flow rate of 5-10 sccm.

[0015] Specifically, the first mixed carrier gas is used to regulate the volatilization rate and gas-phase transport state of the precursor during the heating stage, while the second mixed carrier gas is used to regulate the reaction deposition process of the precursor on the substrate surface during the heat preservation growth stage. Furthermore, during the heating stage, a higher Ar / H2 mixed gas flow rate promotes the formation and stable transport of the Te, Cu, and Fe precursors into gaseous precursors, while reducing the impact of residual oxygen or moisture in the furnace cavity on the reaction process. During the heat preservation growth stage, a lower Ar and H2 flow rate slows down the transport rate of the gaseous precursors, prolonging their residence time near the substrate, thereby promoting the adsorption, diffusion, nucleation, and lateral growth of the precursors on the substrate surface. Through the above two-stage carrier gas flow rate regulation, the compositional uniformity, crystallinity, and thickness controllability of the thin film can be improved.

[0016] In one embodiment, the substrate is a mica substrate; the pretreatment process involves sequentially immersing the mica substrate in acetone, anhydrous ethanol, and deionized water, ultrasonically cleaning each for 10–20 min, and then annealing the mica substrate at 600°C for 1–2 h under an Ar atmosphere.

[0017] In one embodiment, the mica substrate is annealed and then cleaved to remove the surface layer of the mica substrate and expose fresh cleavage surfaces, resulting in a clean and smooth mica substrate with fresh cleavage surfaces.

[0018] In one embodiment, step S5 includes a first cooling stage and a second cooling stage. The first cooling stage reduces the temperature from the deposition temperature to 100°C to 400°C at a cooling rate of 10°C / min to 20°C / min. The second cooling stage reduces the temperature from 100°C to 400°C to room temperature at a cooling rate of 20°C / min to 50°C / min.

[0019] In one embodiment, in step S3, the carrier gas treatment method involves evacuating the CVD reactor until the vacuum level inside the CVD reactor reaches 1×10⁻⁶. -5 ~1×10 -3 After Pa, Ar is introduced at a flow rate of 200–300 sccm. After restoring to normal pressure, Ar is introduced for another 10–15 min. After the introduction is complete, Ar and H2 are introduced simultaneously, with Ar and H2 flow rates of 100–130 sccm and 10–20 sccm, respectively, to form a stable carrier gas atmosphere. The introduction time is 3–5 min.

[0020] In one embodiment, in step S2, the first carrier further includes an alkali metal salt compound. Preferably, the alkali metal salt compound includes NaCl.

[0021] In one embodiment, during step S2, when the substrate is placed, the clean surface of the substrate is located 8-10 mm above the first carrier.

[0022] In one embodiment, during step S2, when the substrate is placed, the clean surface may be parallel to the horizontal plane or at an angle of 0° to 45°.

[0023] In one embodiment, in step S1, the elemental Cu is Cu powder with a purity ≥99.9% and a particle size of 50 nm to 200 nm; the elemental Fe is Fe powder with a purity ≥99.9% and a particle size of 50 to 200 nm; and the elemental Te is Te powder with a purity ≥99.9% and a particle size of 50 to 200 nm. Preferably, the purity of the Cu powder, Fe powder, and Te powder is ≥99.99%.

[0024] The present invention also provides a two-dimensional Cu prepared by any of the above preparation methods. x Fe y Te crystalline thin films.

[0025] In one embodiment, two-dimensional Cu x Fe y The thickness of a single Te crystal thin film is less than or equal to 2 nm.

[0026] Preferably, two-dimensional Cu x Fe y The lateral dimensions of Te crystal thin films are 20~100μm.

[0027] The beneficial effects of this invention are as follows: 1. The two-dimensional Cu provided by this invention x Fe y The Te crystal thin film was prepared by CVD. By adjusting the feed ratio of Cu, Fe, and Te elements, and combining process parameters such as precursor arrangement, substrate pretreatment, carrier gas flow rate, and growth temperature, two-dimensional Cu crystal thin films can be obtained. x Fe y This method enables the tunable preparation of Cu / Fe ratios in Te crystal thin films. It overcomes existing problems in the preparation of two-dimensional ternary transition metal telluride thin films, such as difficulty in adjusting elemental ratios and deviations from expected product composition. Furthermore, it allows for the preparation of Cu crystals with different Cu / Fe ratios to meet various research or application needs. x Fe y Te crystal thin films have good process adjustability and material adaptability.

[0028] 2. The two-dimensional Cu provided by this invention x Fe yThe method for preparing Te crystalline thin films involves partitioning Cu and Fe precursors with Te precursors and synergistically controlling the growth temperature, source region location, substrate location, and carrier gas ratio at different growth stages. This approach helps mitigate mismatches in the volatilization, transport, and reactive deposition processes of multi-element precursors, reducing the likelihood of product composition deviations and impurity phase formation, thereby improving the compositional uniformity and crystallinity of the thin film. Furthermore, differentiated adjustment of the carrier gas flow rate during the heating and holding growth stages can promote the growth of two-dimensional Cu... x Fe y The nucleation, diffusion, and lateral growth of Te crystal thin films on the substrate surface improve the lateral size, thickness uniformity, and crystal integrity of the product, thereby addressing the challenge of synergistic control of structure and composition during the preparation of multi-component two-dimensional materials.

[0029] 3. The two-dimensional Cu provided by this invention x Fe y Te crystal thin films can achieve two-dimensional Cu crystals by optimizing parameters such as substrate pretreatment process, precursor placement, growth temperature, and cooling process. x Fe y Thinning and thickness control of Te crystal films result in products with thinner layer thickness, better surface smoothness, and more uniform thickness distribution. Compared with mechanical exfoliation, this invention improves the reproducibility of sample preparation and product yield; compared with solution methods, it improves the crystallinity, surface cleanliness, and thickness uniformity of the product; and compared with chemical vapor transport, it is more suitable for directly preparing low-dimensional, compositionally tunable two-dimensional Cu. x Fe y Te crystalline thin films provide a stable material basis for subsequent property studies.

[0030] Other features and beneficial effects of the present invention will be further described in the following description. For those skilled in the art, some features and beneficial effects will be clearly understood by reading this specification, or obtained by implementing the technical solutions of the present invention. The objectives, technical solutions, and beneficial effects of the present invention can be achieved through the technical features and combinations thereof recorded in the specification and claims. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating an embodiment of the present invention; Figure 2 This is a schematic diagram of the CVD reaction apparatus used in an embodiment of the present invention; Figure 3 This is an overview of the characterization results for Embodiment 1 of the present invention; Figure 3 (a) is the Fe element EDS-Mapping diagram of Embodiment 1 of the present invention; Figure 3 (b) is the Cu element EDS-Mapping diagram of Embodiment 1 of the present invention; Figure 3 (c) is the Te element EDS-Mapping diagram of Embodiment 1 of the present invention; Figure 3 (d) is the Raman spectrum of Example 1 of the present invention; Figure 3 (e) is an element distribution diagram of Embodiment 1 of the present invention; Figure 4 This is an overall diagram of the characterization results of Embodiment 2 of the present invention; Figure 4 (a) is the Fe element EDS-Mapping diagram of Embodiment 2 of the present invention; Figure 4 (b) is the Cu element EDS-Mapping diagram of Embodiment 2 of the present invention; Figure 4 (c) is the Te element EDS-Mapping diagram of Embodiment 2 of the present invention; Figure 4 (d) is the Raman spectrum of Example 2 of the present invention; Figure 4 (e) is an element distribution diagram of Embodiment 2 of the present invention; Figure 5 This is an overall diagram of the characterization results of Embodiment 3 of the present invention; Figure 5 (a) is the Fe element EDS-Mapping diagram of Embodiment 3 of the present invention; Figure 5 (b) is the Cu element EDS-Mapping diagram of Example 3 of the present invention; Figure 5 (c) is the EDS-Mapping diagram of the Te element in Embodiment 3 of the present invention; Figure 5 (d) is the Raman spectrum of Example 3 of the present invention; Figure 5 (e) is an element distribution diagram of Embodiment 3 of the present invention; Figure 6 This is an overall diagram of the characterization results of Example 4 of the present invention; Figure 6 (a) is the Fe element EDS-Mapping diagram of Example 4 of the present invention; Figure 6 (b) is the Cu element EDS-Mapping diagram of Example 4 of the present invention; Figure 6 (c) is the EDS-Mapping diagram of the Te element in Embodiment 4 of the present invention; Figure 6 (d) is the Raman spectrum of Example 4 of the present invention; Figure 6 (e) is an element distribution diagram of Embodiment 4 of the present invention; Figure 7 These are optical microscope images at different magnifications for Embodiment 4 of the present invention; Figure 7 (a) is a 10x magnified optical microscope image of Embodiment 4 of the present invention; Figure 7 (b) is a 20x magnified optical microscope image of Embodiment 4 of the present invention; Figure 7 (c) is a 50x magnified optical microscope image of Embodiment 4 of the present invention; Figure 7 (d) is a 100x magnified optical microscope image of Embodiment 4 of the present invention; Figure 8 This is a 100x magnified optical microscope image of Embodiment 4 of the present invention; Figure 9 This is an AFM scan image from Embodiment 4 of the present invention; Figure 10 This is a general diagram of the characterization results of Comparative Example 1 of the present invention; Figure 10 (a) is the Fe element EDS-Mapping diagram of Comparative Example 1 of the present invention; Figure 10 (b) is the EDS-Mapping detection image of Cu element in Comparative Example 1 of the present invention; Figure 10 (c) is the Te element EDS-Mapping diagram of Comparative Example 1 of the present invention; Figure 10 (d) is the Raman spectrum of Comparative Example 1 of the present invention; Figure 10 (e) is the element distribution diagram of Comparative Example 1 of the present invention; Figure 11 This is a summary diagram of the XRD characterization results of Examples 1 to 4 of the present invention; Figure 11 (a) are the XRD patterns of embodiments 1 to 4 of the present invention in the range of diffraction angle from 10° to 60°; Figure 11 (b) are the XRD patterns of embodiments 1 to 4 of the present invention in the range of diffraction angle from 10° to 20°; Figure 12 These are optical microscope images at different magnifications for Comparative Example 2 of this invention; Figure 12 (a) is a 20x magnified optical microscope image of Comparative Example 2 of the present invention; Figure 12 (b) is a 100x magnified optical microscope image of Comparative Example 2 of the present invention; Figure 13 This is a 20x magnified optical microscope image of another test area in Comparative Example 2 of the present invention; Figure 14 This is a 100x magnified optical microscope image of another test area in Comparative Example 2 of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and beneficial effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them; the technical features in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should all fall within the protection scope of the present invention.

[0033] In the description of this invention, it should be noted that the terms used in this invention, including technical and scientific terms, should have the same meaning as commonly understood by those skilled in the art to which this invention pertains, and should not be construed as limiting the invention. It should also be understood that the terms used in this invention should be understood in conjunction with the context of this specification and their meaning in the relevant technical field, and should not be interpreted in an idealized or overly limiting sense, unless otherwise expressly defined in this invention.

[0034] Example 1 A two-dimensional Cu x Fe y The preparation method of Te crystal thin film is as follows: S1. Select a mica substrate and place it sequentially in acetone, ethanol, and deionized water, respectively, and ultrasonically clean it for 12 minutes each at an ultrasonic power of 120W to remove organic matter, particles, and other impurities from the surface of the mica substrate. Subsequently, place the ultrasonically cleaned mica substrate in a high-temperature furnace and anneal it at 600°C for 90 minutes under Ar atmosphere and atmospheric pressure. After annealing, cool it to room temperature. Then, perform cleavage treatment on the annealed mica substrate to remove the surface layer of the mica substrate and expose fresh cleavage surfaces to obtain a pretreated mica substrate. The surface roughness of the clean surface of the pretreated mica substrate is ≤1nm.

[0035] Cu and Fe elements with a purity of 99.9% were weighed at a molar ratio of 1:100. At the same time, Te element was weighed as a reaction precursor, wherein the molar amount of Te element was 1.5 times the sum of the molar amounts of Cu and Fe elements. Cu, Fe and Te elements were ground into uniform powders and dried at 100℃ for 3 hours for later use.

[0036] S2. After uniformly mixing the Cu powder and Fe powder obtained in step S1, place them in a first carrier located in the growth zone. The first carrier is a quartz boat, and a small amount of NaCl is added as an auxiliary agent. Place the Te powder in a second carrier, which is also a quartz boat, and place the second carrier in the sublimation zone upstream of the growth zone. The distance between the two quartz boats is 25 cm. Place the pretreated substrate 10 mm above the first carrier, so that the clean surface of the substrate faces the precursor powder and is parallel to the horizontal plane. The distance between the projection of the substrate on the horizontal plane and the projection of the second carrier on the horizontal plane is 25 cm.

[0037] After S3 and S2 are completed, seal the furnace chamber of the CVD reactor and evacuate it to a pressure of 5 × 10⁻⁶. -4 Pa, then Ar gas is introduced for flushing at a flow rate of 250 sccm. The vacuum-Ar gas flushing operation is repeated 4 times to thoroughly remove impurities and moisture from the furnace cavity. While maintaining the continuous introduction of Ar gas, H2 gas is introduced simultaneously, with the total flow rate of Ar and H2 gas controlled at 120 sccm, of which the flow rate of Ar gas is 100 sccm and the flow rate of H2 gas is 20 sccm. Subsequently, the temperature of the tube furnace growth zone is raised to 720℃ at a heating rate of 12℃ / min, and the temperature of the sublimation zone is stabilized at 400℃.

[0038] S4. After the temperature stabilizes, adjust the flow rates of Ar and H2 to 60 sccm and 6 sccm respectively, maintaining the growth zone temperature at 720℃ and the sublimation zone temperature at 400℃. Maintain constant temperature growth for 30 minutes to allow the gaseous precursor to react and deposit on the substrate surface, forming a two-dimensional Cu. x Fe y Te crystalline thin films.

[0039] After the film growth in steps S5 and S4 is completed, stop heating, shut off the H2 gas supply while maintaining a continuous Ar gas flow, and cool the tube furnace to room temperature at a cooling rate of 30°C / min. Then, stop the Ar gas flow, open the furnace chamber, and remove the two-dimensional Cu deposited on the tube. x Fe y The substrate of the Te thin film, thus obtaining the two-dimensional Cu x Fe y Te materials.

[0040] SEM, EDS-Mapping, Raman spectroscopy, and XRD were performed on multiple locations of the sample obtained in Example 1. The specific results are as follows: Figure 3 and Figure 11 As shown in the figure. The test results indicate that the molar ratio of Cu, Fe, and Te in the sample obtained in Example 1 is approximately 0.14:0.86:1, and the elemental distribution is relatively uniform. The Raman spectrum shows corresponding characteristic vibrational peaks, and the XRD results show no obvious impurity peaks. This demonstrates that the method of this example can prepare two-dimensional Cu with adjustable composition and good crystallinity. x Fe y Te crystalline thin films.

[0041] Example 2 A two-dimensional Cu x Fe y The preparation method of Te crystal thin film is as follows: S1. Select a mica substrate and place it sequentially in acetone, ethanol, and deionized water, respectively, and ultrasonically clean it for 12 minutes each at an ultrasonic power of 120W to remove organic matter, particles, and other impurities from the surface of the mica substrate. Subsequently, place the ultrasonically cleaned mica substrate in a high-temperature furnace and anneal it at 600°C for 90 minutes under Ar atmosphere and atmospheric pressure. After annealing, cool it to room temperature. Then, perform cleavage treatment on the annealed mica substrate to remove the surface layer of the mica substrate and expose fresh cleavage surfaces to obtain a pretreated mica substrate. The surface roughness of the clean surface of the pretreated mica substrate is ≤1nm.

[0042] Cu and Fe elements with a purity of 99.9% were weighed in a molar ratio of 10:100. At the same time, Te element was weighed as a reaction precursor, wherein the molar amount of Te element was 1.2 times the sum of the molar amounts of Cu and Fe elements. Cu, Fe and Te elements were ground into uniform powders and dried at 100℃ for 3 hours for later use.

[0043] S2. After uniformly mixing the Cu powder and Fe powder obtained in step S1, place them in a first carrier located in the growth zone. The first carrier is a quartz boat, and a small amount of NaCl is added as an auxiliary agent. Place the Te powder in a second carrier, which is also a quartz boat, and place the second carrier in the sublimation zone upstream of the growth zone. The distance between the two quartz boats is 20 cm. Place the pretreated substrate 10 mm above the first carrier, so that the clean surface of the substrate faces the precursor powder and is parallel to the horizontal plane. The distance between the projection of the substrate on the horizontal plane and the projection of the second carrier on the horizontal plane is 20 cm.

[0044] S3. After assembly in step S2, seal the furnace chamber of the CVD reactor and evacuate it to a vacuum level of 5 × 10⁻⁶. -4Pa, then Ar gas is introduced for flushing at a flow rate of 250 sccm. The vacuum-Ar gas flushing operation is repeated 4 times to thoroughly remove impurities and moisture from the furnace cavity. While maintaining the continuous introduction of Ar gas, H2 gas is introduced simultaneously, with the total flow rate of Ar and H2 gas controlled at 120 sccm. The flow rates of Ar and H2 gas are 100 sccm and 20 sccm, respectively. The temperature of the tube furnace growth zone is raised to 820℃ at a heating rate of 12℃ / min, and the temperature of the sublimation zone is stabilized at 450℃.

[0045] S4. After the temperature stabilizes, adjust the flow rates of Ar and H2 to 70 sccm and 7 sccm respectively, maintaining the growth zone temperature at 820℃ and the sublimation zone temperature at 450℃. Maintain constant temperature growth for 20 minutes to allow the gaseous precursor to react and deposit on the substrate surface, forming a two-dimensional Cu. x Fe y Te crystalline thin films.

[0046] After the film growth in step S5 and S4 is completed, stop heating, shut off the H2 gas supply while maintaining a continuous Ar gas supply, and cool the tube furnace to 400°C at a cooling rate of 20°C / min. Then, cool it to room temperature at a cooling rate of 30°C / min. Finally, stop the Ar gas supply, open the furnace chamber, and remove the two-dimensional Cu deposited on the tube furnace. x Fe y The substrate of the Te thin film, thus obtaining the two-dimensional Cu x Fe y Te materials.

[0047] SEM, EDS-Mapping, Raman spectroscopy, and XRD were performed on multiple locations of the sample obtained in Example 2. The specific results are as follows: Figure 4 and Figure 11 As shown in the figure. The test results indicate that the molar ratio of Cu, Fe, and Te in the sample obtained in Example 2 is approximately 0.36:0.64:1, and the elemental distribution is relatively uniform. The Raman spectrum shows corresponding characteristic vibrational peaks, and the XRD results show no obvious impurity peaks. This indicates that the method of this example can prepare two-dimensional Cu with adjustable composition and good crystallinity. x Fe y Te crystalline thin films.

[0048] Example 3 A two-dimensional Cu x Fe y The preparation method of Te crystal thin film is as follows: S1. Select a mica substrate and place it sequentially in acetone, ethanol, and deionized water, respectively, and ultrasonically clean it for 12 minutes each at an ultrasonic power of 120W to remove organic matter, particles, and other impurities from the surface of the mica substrate. Subsequently, place the ultrasonically cleaned mica substrate in a high-temperature furnace and anneal it at 600°C for 90 minutes under Ar atmosphere and atmospheric pressure. After annealing, cool it to room temperature. Then, perform cleavage treatment on the annealed mica substrate to remove the surface layer of the mica substrate and expose fresh cleavage surfaces to obtain a pretreated mica substrate. The surface roughness of the clean surface of the pretreated mica substrate is ≤1nm.

[0049] Cu and Fe elements with a purity of 99.9% were selected at a molar ratio of 20:100. At the same time, Te elements with a molar amount 1.5 times that of the sum of the molar amounts of Cu and Fe elements were selected as the reaction precursor. The three elements were ground into powder and then dried at 100℃ for 3 hours.

[0050] S2. After uniformly mixing the Cu powder and Fe powder obtained in step S1, place them in a first carrier located in the growth zone. The first carrier is a quartz boat, and a small amount of NaCl is added as an auxiliary agent. Place the Te powder in a second carrier, which is also a quartz boat, and place the second carrier in the sublimation zone upstream of the growth zone. The distance between the two quartz boats is 25 cm. Place the pretreated substrate 8 mm above the first carrier, so that the clean surface of the substrate faces the precursor powder and is parallel to the horizontal plane. The distance between the projection of the substrate on the horizontal plane and the projection of the second carrier on the horizontal plane is 25 cm.

[0051] S3. After assembly in step S2, seal the furnace chamber of the CVD reactor and evacuate it to a vacuum level of 5 × 10⁻⁶. -4 Pa, then Ar gas is introduced for flushing at a flow rate of 250 sccm. The vacuum-Ar gas flushing operation is repeated 4 times to thoroughly remove impurities and moisture from the furnace cavity. While maintaining the continuous introduction of Ar gas, H2 gas is introduced simultaneously, with the total flow rate of Ar and H2 gas controlled at 120 sccm. The flow rates of Ar and H2 gas are 100 sccm and 20 sccm, respectively. The temperature of the tube furnace growth zone is raised to 900℃ at a heating rate of 12℃ / min, and the temperature of the sublimation zone is stabilized at 500℃.

[0052] S4. After the temperature stabilizes, adjust the flow rates of Ar and H2 to 80 sccm and 8 sccm respectively, maintaining the growth zone temperature at 900℃ and the sublimation zone temperature at 500℃. Maintain constant temperature growth for 20 minutes to allow the gaseous precursor to react and deposit on the substrate surface, forming a two-dimensional Cu. x Fe y Te crystalline thin films.

[0053] After the film growth in steps S5 and S4 is completed, stop heating, shut off the H2 gas supply while maintaining a continuous Ar gas flow, and cool the tube furnace to 300°C at a cooling rate of 20°C / min. Then, cool it to room temperature at a cooling rate of 30°C / min. Finally, stop the Ar gas flow, open the furnace chamber, and remove the two-dimensional Cu deposited on the tube furnace. x Fe y The substrate of the Te thin film, thus obtaining the two-dimensional Cu x Fe y Te materials.

[0054] SEM, EDS-Mapping, Raman spectroscopy, and XRD were performed on multiple locations of the sample obtained in Example 3. The specific results are as follows: Figure 5 and Figure 11 As shown in the figure. The test results show that the molar ratio of Cu, Fe and Te in the sample obtained in Example 3 is about 0.75:0.25:1, the element distribution is relatively uniform, the Raman spectrum shows the corresponding characteristic vibration peaks, and the XRD results show no obvious impurity phase peaks. This indicates that the method of this example can prepare a two-dimensional CuxFeyTe crystal film with high Cu content and good crystal quality.

[0055] Example 4 The preparation method is the same as in Example 1, except that Cu and Fe with a purity of 99.9% are selected according to a molar ratio of 50:100.

[0056] Optical microscopy, AFM, SEM, Raman spectroscopy, and XRD were performed on multiple locations of the sample obtained in Example 4. Specific results are as follows: Figures 6-9 and Figure 11 As shown in the figure. The detection results indicate that the molar ratio of Cu, Fe, and Te in the sample obtained in Example 4 is approximately 0.82:0.18:1, indicating a relatively uniform elemental distribution. The Raman spectrum shows corresponding characteristic vibrational peaks, and the XRD results show no obvious impurity phase peaks. AFM detection results show that the two-dimensional Cu obtained in Example 4... x Fe y The Te crystal film exhibits a thin-layer nanosheet structure with a thickness of less than or equal to 2 nm, indicating that the Cu content in the film can be further increased by adjusting the Cu / Fe feed ratio, thus obtaining a thin-layer two-dimensional Cu film. x Fe y Te crystalline thin films.

[0057] To facilitate comparison of the changes in the Cu and Fe element ratios in Examples 1-4, the Cu, Fe, and Te element contents obtained from EDS detection were normalized. Specifically, when calculating the molar ratio of Cu, Fe, and Te, the Te element content was used as the normalization benchmark, and the relative contents of Cu and Fe were proportionally converted so that the sum of the relative contents of Cu and Fe corresponded to the total amount of metal elements in the Te-based compound. This yielded the normalized molar ratios of Cu, Fe, and Te in each example.

[0058] Comparative Example 1 A method for preparing a two-dimensional FeTe crystal thin film, comprising the following steps: S1. Select a mica substrate and place it sequentially in acetone, ethanol, and deionized water, respectively, and ultrasonically clean it for 12 minutes each at an ultrasonic power of 120W to remove organic matter, particles, and other impurities from the surface of the mica substrate. Subsequently, place the ultrasonically cleaned mica substrate in a high-temperature furnace and anneal it at 600°C for 90 minutes under Ar atmosphere and atmospheric pressure. After annealing, cool it to room temperature. Then, perform cleavage treatment on the annealed mica substrate to remove the surface layer of the mica substrate and expose fresh cleavage surfaces to obtain a pretreated mica substrate. The surface roughness of the clean surface of the pretreated mica substrate is ≤1nm.

[0059] Weigh 100 mg of Fe elemental purity (99.9%) and simultaneously weigh Te elemental as a reaction precursor, wherein the molar amount of Te elemental is 1.5 times the molar amount of Fe elemental. Grind the Fe elemental and Te elemental into uniform powders and dry them at 100℃ for 3 hours for later use.

[0060] S2. Place the Fe powder obtained in step S1 in a first carrier located in the growth zone. The first carrier is a quartz boat, and a small amount of NaCl is added as an auxiliary agent. Place the Te powder in a second carrier, which is also a quartz boat. Place the second carrier in the sublimation zone upstream of the growth zone, with a distance of 15 cm between the two quartz boats. Place the pretreated substrate 12 mm above the first carrier, with the clean surface of the substrate facing the precursor powder and parallel to the horizontal plane. The distance between the projection of the substrate on the horizontal plane and the projection of the second carrier on the horizontal plane is 30 cm.

[0061] S3. After assembly in step S2, seal the furnace chamber of the CVD reactor and evacuate it to a vacuum level of 5 × 10⁻⁶. -4Pa, then Ar gas is introduced for flushing at a flow rate of 250 sccm. The vacuum-Ar gas flushing operation is repeated 4 times to thoroughly remove impurities and moisture from the furnace cavity. While maintaining the continuous introduction of Ar gas, H2 gas is introduced simultaneously, with the total flow rate of Ar and H2 gas controlled at 120 sccm. The flow rates of Ar and H2 gas are 100 sccm and 20 sccm, respectively. The temperature of the tube furnace growth zone is raised to 680℃ at a heating rate of 12℃ / min, and the temperature of the sublimation zone is stabilized at 370℃.

[0062] S4. After the temperatures of the growth zone and the sublimation zone stabilize, adjust the flow rates of Ar gas and H2 gas to 60 sccm and 6 sccm, respectively, and maintain the temperature of the growth zone at 680℃ and the temperature of the sublimation zone at 370℃. Maintain constant temperature growth for 30 min to allow the gaseous precursor to react and deposit on the substrate surface to form a two-dimensional thin film.

[0063] After the film growth in steps S5 and S4 is completed, stop heating, shut off H2 gas and keep Ar gas continuously supplied, cool the tube furnace to room temperature at a cooling rate of 30℃ / min, then stop supplying Ar gas, open the furnace chamber, and take out the substrate with the two-dimensional film deposited, thus obtaining the two-dimensional material.

[0064] The sample obtained in Comparative Example 1 was subjected to SEM, EDS-Mapping, and Raman spectroscopy. Specific results are as follows: Figure 10 As shown. Meanwhile, the morphological uniformity of the sample obtained in Comparative Example 1 is poor, and the size distribution range is wide, which is not conducive to improving the consistency of subsequent device performance.

[0065] Comparative Example 2 A two-dimensional Cu x Fe y The preparation method of Te crystal thin film is as follows: S1. Select a mica substrate and place it sequentially in acetone, ethanol, and deionized water, respectively, and ultrasonically clean it for 12 minutes each at an ultrasonic power of 120W to remove organic matter, particles, and other impurities from the surface of the mica substrate. Subsequently, place the ultrasonically cleaned mica substrate in a high-temperature furnace and anneal it at 600°C for 90 minutes under Ar atmosphere and atmospheric pressure. After annealing, cool it to room temperature. Then, perform cleavage treatment on the annealed mica substrate to remove the surface layer of the mica substrate and expose fresh cleavage surfaces to obtain a pretreated mica substrate. The surface roughness of the clean surface of the pretreated mica substrate is ≤1nm.

[0066] Cu and Fe elements with a purity of 99.9% were selected in a 1:1 molar ratio. At the same time, Te elements with a molar amount 1.5 times that of the sum of the molar amounts of Cu and Fe elements were selected as the reaction precursor. The three elements were ground into powder and then dried at 100℃ for 3 hours.

[0067] S2. After uniformly mixing the Cu powder and Fe powder obtained in step S1, place them in a first carrier located in the growth zone. The first carrier is a quartz boat, and a small amount of NaCl is added as an auxiliary agent. Place the Te powder in a second carrier, which is also a quartz boat, and place the second carrier in the sublimation zone upstream of the growth zone. The distance between the two quartz boats is 15 cm. Place the pretreated substrate 12 mm above the first carrier, so that the clean surface of the substrate faces the precursor powder and is parallel to the horizontal plane. The distance between the projection of the substrate on the horizontal plane and the projection of the second carrier on the horizontal plane is 15 cm.

[0068] S3. After assembly in step S2, seal the furnace chamber of the CVD reactor and evacuate it to a vacuum level of 5 × 10⁻⁶. -4 Pa, then Ar gas is introduced for flushing at a flow rate of 250 sccm. The vacuum-Ar gas flushing operation is repeated 4 times to thoroughly remove impurities and moisture from the furnace cavity. While maintaining the continuous introduction of Ar gas, H2 gas is introduced simultaneously, with the total flow rate of Ar and H2 gas controlled at 120 sccm. The flow rates of Ar and H2 gas are 100 sccm and 20 sccm, respectively. The temperature of the tube furnace growth zone is raised to 680℃ at a heating rate of 12℃ / min, and the temperature of the sublimation zone is stabilized at 370℃.

[0069] S4. After the temperature stabilizes, adjust the flow rates of Ar gas and H2 gas to 60 sccm and 6 sccm respectively, maintain the temperature of the growth zone at 680℃ and the temperature of the sublimation zone at 370℃, and grow at a constant temperature for 30 minutes. After the mixed precursors volatilize, they are deposited on the substrate surface to form a two-dimensional thin film.

[0070] After the film growth in steps S5 and S4 is completed, stop heating, shut off H2 gas and keep Ar gas continuously supplied, cool the tube furnace to room temperature at a cooling rate of 30℃ / min, then stop supplying Ar gas, open the furnace chamber, and take out the substrate with the two-dimensional film deposited, thus obtaining the two-dimensional material.

[0071] The sample obtained in Comparative Example 2 was examined using an optical microscope, and the results are as follows: Figures 12-14 As shown. By Figures 12-14 As can be seen, the nanosheets in Comparative Example 2 are sparsely distributed with many gaps in local areas, making it difficult to form a film with good continuity. Furthermore, the morphological uniformity of the sample obtained in Comparative Example 2 is poor, and the size distribution range is wide, which is detrimental to improving the consistency of subsequent device performance.

[0072] As can be seen from the Raman spectra and elemental distribution results of Examples 1-4 and Comparative Example 1, the relevant results are as follows: Figures 3-6 and Figure 10 As shown, the Raman spectra of Examples 1 to 4 are all in the range of 50 to 250 cm⁻¹. -1A relatively obvious vibration peak appears within the range. This low-frequency region is usually related to metal-tellurium bond and tellurium lattice vibrations, and can serve as an important basis for judging the crystal structure and phase composition of transition metal tellurides. Combined with the EDS elemental distribution results, it can be seen that Fe, Cu, and Te elements in Examples 1-4 can all be detected in the sample region and exhibit a relatively uniform distribution, indicating that the method of this invention can obtain two-dimensional Cu containing Cu, Fe, and Te elements. x Fe y Te crystal thin films were obtained, and the resulting samples exhibited good compositional uniformity and crystal characteristics.

[0073] Specifically, the significant peak position in Example 1 is 81 cm⁻¹. -1 120cm -1 and 143cm -1 The significant peak position in Example 2 was 81 cm⁻¹. -1 100cm -1 120cm -1 and 145cm -1 The significant peak position in Example 3 was 79 cm⁻¹. -1 96cm -1 120cm -1 143cm -1 and 210cm -1 The significant peak position in Example 4 was 67 cm⁻¹. -1 79cm -1 101cm -1 120cm -1 146cm -1 and 212cm -1 Examples 1-4 all have a diameter of 79cm. -1 -81cm -1 120cm -1 and 143cm -1 -146cm -1 The nearby Raman characteristic peaks, while Comparative Example 1 mainly shows a 93cm peak. -1 120cm -1 and 140cm -1 Characteristic peaks in the vicinity. Compared with Comparative Example 1, the low-frequency peak positions and shapes in Examples 1-4 show a regular change with increasing Cu content, indicating that the introduction of Cu affects the Fe-Te / Cu-Te related vibrational modes and the local lattice environment. This trend corresponds to the change in the Cu / Fe element ratio obtained by EDS detection, indicating that the method of the present invention can change the relative content of Cu and Fe in the final film by adjusting the Cu / Fe feed ratio, and can affect the two-dimensional Cu... x Fe y The lattice vibration characteristics of Te crystal thin films exert a modulating effect. Among them, 120cm-1 The nearby vibrational peaks were observed in all embodiments, indicating that similar tellurium lattice vibrational characteristics were maintained in samples with different Cu contents; 79 cm⁻¹ -1 ~81cm -1 And 143cm -1 ~146cm -1 The changes in the position of nearby peaks reflect the influence of variations in the proportion of metallic elements on lattice vibrations and the local bonding environment. With increasing Cu content, the 96 cm⁻¹ peak position... -1 ~101cm -1 The gradual appearance or enhancement of nearby vibrational peaks further indicates that the phonon vibrational modes of the sample changed after Cu participation. The aforementioned Raman peak position changes corroborate the EDS elemental distribution results, supporting the view that the samples obtained in Examples 1-4 were not simply FeTe control samples, but rather formed Cu mixtures involving Cu, Fe, and Te. x Fe y Te crystal thin films. Therefore, this invention achieves two-dimensional Cu crystal thin films through CVD processes. x Fe y The adjustable preparation of Cu and Fe ratios in Te thin films improved the compositional uniformity and crystallization characteristics of the films to a certain extent, providing a material basis for subsequent research on the structure control and performance of this type of two-dimensional ternary transition metal telluride thin films.

[0074] Depend on Figure 11 (a) It can be seen that the two-dimensional Cu obtained in Examples 1-4 x Fe y The Te crystalline thin films exhibited corresponding crystal diffraction characteristics within the testing range, and no obvious impurity phase diffraction peaks were observed within the XRD testing range. Combined with Raman and EDS results, this indicates that the samples possess good crystal characteristics and compositional homogeneity. Figure 11 (b) It can be seen that as the Cu content increases, the positions of the relevant diffraction peaks shift to a certain extent. According to the Bragg diffraction relation, the change in diffraction peak positions is usually related to the change in interplanar spacing; when the interplanar spacing d decreases, the corresponding diffraction angle will shift towards higher angles. Therefore, the above-mentioned peak position changes can illustrate the effect of adjusting the Cu content on two-dimensional Cu... x Fe y The lattice parameters or local lattice environment of the Te crystal thin film were affected. This result is corroborated by changes in Raman spectrum peak positions and EDS elemental ratios, further demonstrating that the present invention can control the composition and crystal structure characteristics of the thin film by adjusting the Cu / Fe feed ratio.

[0075] Meanwhile, the Cu / Fe molar ratios and normalized elemental molar ratios of Examples 1-4 were compared with the actual Cu / Fe elemental molar ratios in the final prepared two-dimensional CuxFeyTe crystal films, and the results are shown in Table 1.

[0076] Table 1 Comparison of Data from Examples 1-4

[0077] As shown in Table 1, this invention achieves targeted adjustment of the actual Cu / Fe molar ratio in the product by controlling the Cu / Fe feed molar ratio and adjusting parameters such as growth temperature, precursor position, carrier gas flow rate, and growth time. In the lower Cu / Fe feed ratio range, for example, at feed ratios of 0.01 and 0.10, the actual Cu / Fe molar ratios in the product are 0.1627 and 0.5625, respectively, both higher than the corresponding feed molar ratios. This indicates that within this range, the proportion of Cu entering the film has a certain amplification effect relative to the feed ratio. This phenomenon may be related to the differences in the volatilization, transport, adsorption, and surface diffusion behaviors of Cu and Fe precursors under high-temperature conditions. As the Cu / Fe feed ratio further increases, for example, from 0.20 to 0.50, the actual Cu / Fe molar ratio in the product increases from 3.0000 to 4.5556, with the increase becoming gradual. This indicates that under higher Cu content conditions, the proportion of Cu and Fe elements entering the film may be affected by the adsorption sites on the substrate surface, competitive adsorption, and the nucleation growth process, making the relationship between the feed ratio and the final film element ratio not a simple linear one.

[0078] As can be seen from the above, the two-dimensional Cu provided by the present invention x Fe y The method for preparing Te crystal thin films can establish the correspondence between the Cu / Fe molar ratio and the final elemental ratio of the thin film, providing a basis for the preparation of two-dimensional Cu crystal thin films. x Fe y The controllable fabrication of Te crystal thin films provides a process reference. Those skilled in the art can prepare two-dimensional Cu crystals with different Cu / Fe elemental ratios by adjusting the Cu / Fe feed ratio and related growth parameters, according to the target film composition requirements. x Fe y Te crystalline thin films provide a material basis for subsequent research on composition regulation, structure regulation, and related properties.

[0079] It should be noted that the specific parameters or commonly used reagents in the above embodiments are specific embodiments or preferred embodiments under the concept of the present invention, and are not intended to limit the scope of protection of the present invention; those skilled in the art can make adaptive adjustments according to actual needs within the concept and scope of protection of the present invention.

[0080] In addition, unless otherwise specified, the raw materials used may be commercially available products in the field, or prepared by conventional methods in the field.

[0081] Meanwhile, the results of Comparative Examples 1 and 2 show that, under conditions of no Cu addition, or a Cu / Fe feed ratio of 1:1 but a low growth temperature, the resulting films exhibit a sparse distribution of nanosheets and numerous gaps in localized areas, making it difficult to form films of good quality. Furthermore, the samples obtained in Comparative Examples 1 and 2 show poor morphological uniformity and a wide size distribution range, which is detrimental to improving the consistency of subsequent device performance.

[0082] In summary, the two-dimensional Cu provided by this invention x Fe y The method for preparing Te crystal thin films can be used for two-dimensional Cu x Fe y The ratio of Cu and Fe elements in Te crystal thin films can be effectively controlled, so that the final product can adapt to different composition adjustment and performance research needs, and has good process adjustability and material adaptability.

[0083] Furthermore, those skilled in the art should understand that although there are multiple problems in the prior art, the embodiments or technical solutions of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the background art simultaneously. Those skilled in the art should also understand that any content not expressly described in the claims should not be construed as a limitation on the scope of protection of the claims.

[0084] Although terms such as precursor are frequently used herein, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the technical solutions of this invention; interpreting them as any additional limitation is inconsistent with the spirit of this invention. Terms such as "first," "second," etc., in the specification and claims of the embodiments of this invention, if present, are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the substance of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A two-dimensional Cu x Fe y The method for preparing Te crystal thin films is characterized by, The steps are as follows: S1. Select Cu, Fe, and Te as precursors, with a Cu:Fe molar ratio of x1:y1, and the molar amount of Te greater than the sum of the molar amounts of Cu and Fe. Weigh each precursor and grind them into a uniform powder for later use. Select a substrate and pretreat it to ensure that the surface roughness of the clean surface of the substrate is ≤1nm; where x+y=1, 0.01≤x1 / y1≤0.5, and x1 / y1<x / y. S2. After uniformly mixing the Cu and Fe elements ground in step S1, place them in a first carrier and then place the first carrier in the growth zone of the CVD reactor. Place the Te elements ground in step S1 in a second carrier and place the second carrier in the sublimation zone upstream of the first carrier, with a distance of 20-30 cm between the first and second carriers. Place the pretreated substrate from step S1 in the thin film deposition zone above the growth zone, with the clean surface of the substrate facing the first carrier. In the horizontal plane, the distance between the projection of the substrate onto the horizontal plane and the projection of the second carrier onto the horizontal plane is 20-30 cm. The ratio of the distance between the clean surface of the substrate and the first carrier to the distance between the projection of the substrate onto the horizontal plane and the projection of the second carrier onto the horizontal plane is 1:(20-40). S3. After the assembly in step S2 is completed, the airtightness of the CVD reactor is tested and the carrier gas is treated. After the carrier gas treatment is completed, the growth zone is heated to 700℃~900℃ at a heating rate of 10℃ / min~30℃ / min, and the temperature of the sublimation zone is stabilized at 400℃~500℃. During the heating process, the first mixed carrier gas is introduced to form the precursor into a gaseous precursor and transported with the carrier gas. S4. After the growth zone and sublimation zone mentioned in step S3 reach the preset temperature and stabilize, the second mixed carrier gas is introduced to allow the gaseous precursor to react and deposit on the substrate surface, and the growth is maintained at this temperature for 20 to 30 minutes. S5. After the film growth in step S4 is completed, heating is stopped, and an inert carrier gas is continuously introduced to cool the CVD reactor in the inert carrier gas atmosphere at a cooling rate of 10℃ / min to 50℃ / min until the temperature of the CVD reactor drops to room temperature, thus obtaining two-dimensional Cu. x Fe y Te crystalline thin films.

2. The two-dimensional Cu according to claim 1 x Fe y The method for preparing Te crystal thin films is characterized by: In step S3, the first mixed carrier gas is a mixed gas flow of Ar and H2, with an Ar flow rate of 100-130 sccm and an H2 flow rate of 10-20 sccm; in step S4, the second mixed carrier gas is a mixed gas flow of Ar and H2, with an Ar flow rate of 50-100 sccm and an H2 flow rate of 5-10 sccm.

3. The two-dimensional Cu according to claim 1 x Fe y The method for preparing Te crystal thin films is characterized by: The substrate is a mica substrate; the pretreatment process involves sequentially immersing the mica substrate in acetone, anhydrous ethanol, and deionized water, ultrasonically cleaning each for 10-20 minutes, and then annealing the mica substrate at 600°C for 1-2 hours.

4. The two-dimensional Cu according to claim 3 x Fe y The method for preparing Te crystal thin films is characterized by: The mica substrate is annealed and then cleaved to remove the surface layer of the mica substrate and expose fresh cleavage surfaces, resulting in a pretreated mica substrate with a clean surface.

5. The two-dimensional Cu according to claim 1 x Fe y The method for preparing Te crystal thin films is characterized by: In step S5, the cooling process includes a first cooling stage and a second cooling stage. In the first cooling stage, the temperature is reduced from the deposition temperature to 100℃ to 400℃ at a cooling rate of 10℃ / min to 20℃ / min. In the second cooling stage, the temperature is reduced from 100℃ to 400℃ to room temperature at a cooling rate of 20℃ / min to 50℃ / min.

6. The two-dimensional Cu according to claim 1 x Fe y The method for preparing Te crystal thin films is characterized by: In step S3, the carrier gas treatment method involves evacuating the CVD reactor until the vacuum level inside the CVD reactor reaches 1×10⁻⁶. -5 ~1×10 -3 After Pa, Ar is introduced at a flow rate of 200–300 sccm. After restoring to normal pressure, Ar is introduced for another 10–15 min. After the introduction is complete, Ar and H2 are introduced simultaneously, with Ar and H2 flow rates of 100–130 sccm and 10–20 sccm, respectively, to form a stable carrier gas atmosphere. The introduction time is 3–5 min.

7. The two-dimensional Cu according to claim 1 x Fe y The method for preparing Te crystal thin films is characterized by: In step S2, when the substrate is placed, the clean surface of the substrate is located 8-10 mm above the first carrier.

8. The two-dimensional Cu according to claim 1 x Fe y The method for preparing Te crystal thin films is characterized by: In step S1, Cu element is Cu powder with a purity ≥ 99.9% and a particle size of 50 nm to 200 nm; Fe element is Fe powder with a purity ≥ 99.9% and a particle size of 50 to 200 nm; Te element is Te powder with a purity ≥ 99.9% and a particle size of 50 to 200 nm.

9. A two-dimensional Cu as described in any one of claims 1 to 8 x Fe y Two-dimensional Cu crystal thin films prepared by Te crystal thin film preparation method x Fe y Te crystalline thin films.

10. The two-dimensional Cu according to claim 9 x Fe y Te crystal thin film, characterized in that: The two-dimensional Cu x Fe y The thickness of a single Te crystal thin film is less than or equal to 2 nm.

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