Metastable-state two-dimensional material device and preparation method thereof

Abstract

The invention relates to the technical field of devices, in particular to a metastable-state two-dimensional material device and a preparation method thereof. The method comprises the following steps: carrying out patterned laser cutting treatment on a polyethylene glycol terephthalate film to obtain a mask plate; a substrate is arranged on the surface of one side of the mask plate, the partial surface of the side, facing the mask plate, of the substrate is provided with a metastable-state two-dimensional material layer, the metastable-state two-dimensional material layer is located in an orthographic projection area, on the substrate, of a hollowed-out area of the mask plate, and an intermediate is obtained; the intermediate is subjected to evaporation treatment, evaporation gas penetrates through the hollowed-out area of the mask plate and is deposited on the substrate to form an electrode, and the metastable-state two-dimensional material device is obtained. According to the method, a device which is simple to prepare, low in cost and high in precision is successfully obtained on the basis of laser cutting of a polyethylene glycol terephthalate film, an electrode is directly evaporated on the surface of a metastable-state two-dimensional material in a mask positioning mode, device manufacturing is achieved, and therefore the complex electron beam exposure technology manufacturing process is avoided, and the production efficiency is improved. And the intrinsic electrical property measurement of the metastable-state two-dimensional material is realized.

Description

Technical Field

[0001] This application relates to the field of device technology, and in particular to metastable two-dimensional material devices and their fabrication methods. Background Technology

[0002] In recent years, the intrinsic electrical properties of metastable two-dimensional materials with excellent physical properties have received widespread attention. Taking two-dimensional tetragonal FeSe as an example, metastable materials exhibit excellent superconductivity and tunability. However, due to their metastable nature, it is difficult to directly fabricate devices using processes such as electron beam lithography to test their intrinsic superconductivity, thus greatly limiting the study of the intrinsic electrical properties of these metastable materials. In-situ mask fabrication methods can achieve device fabrication without undergoing a series of processes such as electron beam lithography, greatly avoiding interference with the material's quality, thereby enabling the study of the intrinsic physical properties of these metastable materials. However, current mask fabrication processes often suffer from the problem that higher precision requires more equipment and costs, while lower precision masks, although cheaper, are limited in precision and cannot be used to mask and fabricate devices from small-sized two-dimensional material samples.

[0003] Therefore, there is an urgent need to develop a mask fabrication process that combines high precision and low cost, which is of great significance for promoting the research on the intrinsic electrical properties of two-dimensional materials. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in related technologies. To this end, this application provides a metastable two-dimensional material device and its fabrication method. This method, based on laser cutting of polyethylene terephthalate (PET) films, successfully yields a simple, low-cost, and high-precision device. Furthermore, by using a positioning mask, electrodes are directly deposited onto the surface of the metastable two-dimensional material to fabricate the device, thus avoiding the complex electron beam exposure process and enabling the measurement of the intrinsic electrical properties of the metastable two-dimensional material.

[0005] Therefore, the first aspect of this application provides a method for fabricating metastable two-dimensional material devices, the method comprising the following steps: A patterned laser cutting process is performed on a polyethylene terephthalate film to obtain a photomask. A substrate is disposed on one side surface of the mask plate, and a portion of the surface of the substrate facing the mask plate has a metastable two-dimensional material layer. The metastable two-dimensional material layer is located within the orthogonal projection area of ​​the cutout area of ​​the mask plate onto the substrate, thus obtaining an intermediate body. The intermediate is subjected to vapor deposition, and the vapor deposition gas passes through the hollow area of ​​the mask plate and is deposited on the substrate to form an electrode, thereby obtaining the metastable two-dimensional material device.

[0006] The method provided in this application can avoid interference with the quality of the metastable two-dimensional material itself. While ensuring the device has extremely high precision, the cost is only 1%-2% of that of commercially available photomasks, and it has broad application prospects.

[0007] According to an embodiment of this application, the hollowed-out region includes a first hollowed-out region and a plurality of second hollowed-out regions arranged radially around and connected to the first hollowed-out region. The metastable two-dimensional material layer is located within the orthographic projection region of the first hollowed-out region of the mask onto the substrate. Thus, a device can be formed with multiple electrode structures extending radially from the metastable two-dimensional material as the center, thereby enhancing the electrical performance of the device. The radial electrode structure can optimize the electric field distribution, making the transport path of charge carriers in the two-dimensional material more direct, reducing scattering and obstruction of charge carriers during transport, thereby improving carrier mobility and enhancing the electrical performance of the device.

[0008] According to embodiments of this application, the metastable two-dimensional material comprises FeSe and FeS. x Se y Te 1-x-y At least one of CuFeTe2. Therefore, the device fabrication method provided in this application can avoid interference with the quality of the metastable two-dimensional material itself, thereby enabling the study of the intrinsic physical properties of such metastable materials.

[0009] According to embodiments of this application, the substrate material includes at least one selected from mica, sapphire, Si, and SiO2. This improves the matching of the thermal expansion coefficients between the substrate and the two-dimensional material, reducing the damage to the two-dimensional material caused by thermal stress during temperature changes in the fabrication process.

[0010] According to embodiments of this application, the vapor deposition gas comprises at least one of Au and Ag. Consequently, the resulting electrode exhibits good electrical conductivity and chemical stability. According to an embodiment of this application, the method further includes: fixing the substrate to one side surface of the mask using an adhesive. This prevents changes in the relative position of the substrate and the mask during the vapor deposition process, thus avoiding any impact on the electrode deposition effect.

[0011] According to embodiments of this application, the adhesive comprises polymethyl methacrylate. This achieves excellent bonding with minimal impact on the electrical performance of the device.

[0012] According to embodiments of this application, the minimum width of the patterned laser cutting process is 1μm-2μm. Therefore, the device fabricated by the method provided in this application has extremely high precision.

[0013] According to an embodiment of this application, the method further includes: performing the patterned laser cutting process using a laser micro-cutting system.

[0014] The second aspect of this application provides a metastable two-dimensional material device prepared according to the method described in the first aspect. The metastable two-dimensional material devices prepared by the method provided in this application have the advantages of simple preparation, low cost, and high precision.

[0015] According to embodiments of this application, the metastable two-dimensional material device includes at least one of a Hall six-electrode device, a Hall four-electrode device, a standard four-electrode device, and a two-electrode device. Therefore, the method provided in this application is applicable to the fabrication of various devices.

[0016] The advantages of this application over the prior art are: (1) The method is simple and only requires 3 steps to realize the fabrication of the mask plate and the mask device; (2) Low cost. Under the same precision standard, it only requires 1%-2% of the price of commercially available photomasks to achieve similar results; (3) The equipment requirements are low. It only needs to be used in conjunction with laser cutting. The PET film on the MMI film can be laser cut using the MMI film commonly available on the market to realize the mask production. (4) High precision, enabling the fabrication of device masks with channel widths of 1μm-2μm; (5) It can be used multiple times without affecting subsequent use.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A schematic diagram illustrating the method for fabricating metastable two-dimensional material devices provided in this application; Figure 2 These are schematic diagrams of the metastable two-dimensional material devices obtained in Examples 1 and 2 of this application, wherein (a) is a schematic diagram of the device obtained in Example 1; and (b) is a schematic diagram of the device obtained in Example 2. Figure 3The figures show the RT curves and Auger electron spectroscopy (AES) characterization results of the metastable two-dimensional material device prepared in Comparative Example 1 of this application. (a) shows the RT curve of the FeSe sample. Top left inset: Optical image of the FeSe standard four-electrode device. Bottom right inset: AFM image of FeSe (thickness 29.3 nm); (b) AES spectrum of the FeSe sample. Bottom right inset: SEM image of the FeSe standard four-electrode device and atomic percentages of Fe and Se; (c) Changes in atomic percentages of Fe, Se, Si, and O in the FeSe sample at different sputtering times; (d) Changes in the Fe / Se atomic ratio with sputtering time in Figure (c). Figure 4 The figures show the RT curves and AES characterization results of the metastable two-dimensional material device prepared in Example 1 of this application. (a) is the RT curve of the FeSe standard four-electrode device; upper left inset: optical image of the 10nm thick FeSe standard four-electrode device; lower right inset: dR / dT-T curve of the FeSe standard four-electrode device; (b) and (c) are the RT curves of the sample shown in Figure (a) under the vertical magnetic field (b) and the parallel magnetic field (c); (d) is the Hc2-T / Tc curve of the FeSe standard four-electrode device, with the red and black dashed lines representing the curves fitted by the GL equation. Figure 5 The following are the AES characterization results of the mica substrate surface of the metastable two-dimensional material device prepared in Example 1 of this application, wherein: (a) AES spectrum of FeSe standard four-electrode device; inset: atomic percentage of Fe and Se; (b) changes in the atomic percentage of Fe, Se, C, O and K of FeSe standard four-electrode device on mica surface under different sputtering times; inset: SEM image of FeSe; (c) changes in Fe / Se atomic ratio with sputtering time in Figure (b); inset: optical microscope image of FeSe; Figure 6 Statistical analysis of the Fe / Se atomic ratio on the FeSe surface of the metastable two-dimensional material device prepared in Example 1 of this application; Figure 7 For the superconductivity test of the metastable two-dimensional material device (FeSe two-electrode device) prepared in Example 1 of this application, wherein (a) the FeSe two-electrode device R - T The curves, with the inset showing an optical image of an 8 nm thick two-dimensional FeSe device; (b) and (c) show measurements taken under the vertical magnetic field (b) and parallel magnetic field (c), respectively. R - T Curve; (d) FeSe device H c2 - T / T cThe curves, with red and black dashed lines representing the theoretical curves fitted to the GL equation; Figure 8 For the CuFeTe2 standard four-electrode device in Comparative Example 2 of this application R - T Measurement results, where (ad) represents the values ​​measured using a standard four-electrode device of CuFeTe2 fabricated using the EBL process. R - T Curves, inset: Optical microscope images of the corresponding CuFeTe2 standard four-electrode device; Figure 9 For the metastable two-dimensional material device (two-dimensional tetragonal CuFeTe2) in Embodiment 2 of this application R - T Measurement results; (a) Tetragonal CuFeTe2 with a thickness of 6.5 nm R - T Curves, inset: optical microscope images of the corresponding measuring devices; (b) within the temperature range of 50–345 K. R - T Curve; (c) Normalized derivative of the resistance d of the two-dimensional CuFeTe2 device R / d T The relationship between temperature and temperature.

[0019] Figure 10 This refers to the metastable two-dimensional material devices (CuFeTe2 two-electrode devices) of Examples 3-7 of this application at different thicknesses. R - T Curve; (ae) CuFeTe2 measured by a two-electrode device R - T Curves; Insets: Optical microscope images of the corresponding CuFeTe2 two-electrode device and the corresponding sample thickness; (f) Transition temperature of two-dimensional CuFeTe2 ( T 1 and T 2) Comparison of the relationship with sample thickness. Detailed Implementation

[0020] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0021] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] To facilitate understanding of this application, certain technical and scientific terms are specifically defined below. Unless otherwise expressly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this application pertains.

[0024] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this application but do not exclude other contents.

[0025] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0026] Currently, commercially available 2D material device fabrication masks can be categorized as follows: 1. Silicon-based masks, which can achieve high-precision pattern design with a minimum linewidth of 1-2 μm and flexible flexibility, but the manufacturing and equipment costs are very high, and the fabrication process is complex. High-precision silicon-based masks on the market cost several thousand to tens of thousands of yuan per piece; 2. Stainless steel masks, which have lower costs but can only achieve pattern design with a minimum linewidth of 20 μm; 3. Sapphire masks, which have lower costs but can only achieve pattern design with a minimum linewidth of 50 μm. Therefore, there is an urgent need in the market for a mask and its fabrication process that can simultaneously meet the requirements of high precision and low cost.

[0027] Based on this, the first aspect of this application provides a method for fabricating metastable two-dimensional material devices, which can be referred to in detail. Figure 1 The method includes the following steps: (1) The polyethylene terephthalate film is patterned by laser cutting to obtain a mask.

[0028] Patterned laser cutting of PET film can enable the creation of high-precision device mask patterns. Furthermore, PET film has extremely strong tension and elasticity, maintaining a smooth surface even after cutting complex devices.

[0029] According to a specific embodiment of this application, the minimum width of the patterned laser cutting process is 1μm-2μm. Therefore, the device fabricated by the method provided in this application has extremely high precision.

[0030] According to a specific embodiment of this application, the method further includes: performing the patterned laser cutting process using a laser micro-cutting system. The accuracy of the channel width of the mask is adjusted by modifying the laser aperture size, cutting rate, and microscope magnification of the laser cutting system.

[0031] (2) A substrate is provided on one side surface of the mask plate, and a metastable two-dimensional material layer is provided on a portion of the surface of the substrate facing the mask plate. The metastable two-dimensional material layer is located in the orthographic projection area of ​​the cutout area of ​​the mask plate onto the substrate, thus obtaining an intermediate body.

[0032] According to a specific embodiment of this application, the hollowed-out region includes a first hollowed-out region and a plurality of second hollowed-out regions arranged radially around and connected to the first hollowed-out region. The metastable two-dimensional material layer is located within the orthographic projection region of the first hollowed-out region of the mask onto the substrate. Thus, a device can be formed with multiple electrode structures extending radially from the metastable two-dimensional material as the center, thereby enhancing the electrical performance of the device. The radial electrode structure can optimize the electric field distribution, making the transport path of charge carriers in the two-dimensional material more direct, reducing scattering and obstruction of charge carriers during transport, thereby improving carrier mobility and enhancing the electrical performance of the device.

[0033] According to specific embodiments of this application, the material of the metastable two-dimensional material is not particularly limited. As some specific examples, the material of the metastable two-dimensional material includes FeSe and FeS. x Se y Te 1-x-y At least one of CuFeTe2. Therefore, the device fabrication method provided in this application can avoid interference with the quality of the metastable two-dimensional material itself, thereby enabling the study of the intrinsic physical properties of such metastable materials.

[0034] According to specific embodiments of this application, the material of the substrate is not particularly limited. As some specific examples, the material of the substrate includes at least one selected from mica, sapphire, Si, and SiO2. This allows for matching of the thermal expansion coefficients of the substrate and the two-dimensional material, preventing thermal stress from damaging the two-dimensional material during temperature changes, thereby improving the thermal stability of the device.

[0035] According to a specific embodiment of this application, the method further includes: fixing the substrate to one side surface of the mask using an adhesive. This prevents changes in the relative position of the substrate and the mask during the vapor deposition process, thus avoiding any impact on the electrode deposition effect.

[0036] According to specific embodiments of this application, the type of adhesive is not particularly limited, but includes, among other things, polymethyl methacrylate (PMMA). This allows for excellent bonding with minimal impact on the electrical performance of the device.

[0037] (3) The intermediate is subjected to vapor deposition treatment. The vapor deposition gas passes through the hollow area of ​​the mask plate and is deposited on the substrate to form an electrode, thereby obtaining the metastable two-dimensional material device.

[0038] According to specific embodiments of this application, the composition of the vapor deposition gas is not particularly limited. As some specific examples, the composition of the vapor deposition gas includes at least one of Au and Ag. Therefore, the resulting electrode exhibits good electrical conductivity and chemical stability. According to specific embodiments of this application, the apparatus used for the vapor deposition process is not particularly limited; for example, a vapor deposition machine can be used.

[0039] According to embodiments of this application, a second aspect of this application provides a metastable two-dimensional material device prepared according to the method described in the first aspect. The metastable two-dimensional material devices prepared by the method provided in this application have the advantages of simple preparation, low cost, and high precision.

[0040] According to specific embodiments of this application, the type of metastable two-dimensional material device is not particularly limited. As some specific examples, the metastable two-dimensional material device includes at least one of a Hall six-electrode device, a Hall four-electrode device, a standard four-electrode device, and a two-electrode device. Therefore, the method provided in this application is applicable to the fabrication of a variety of devices.

[0041] The following will explain the solution of this application with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0042] Comparative Example 1 A standard four-electrode device was constructed using electron beam lithography (EBL), and the metastable two-dimensional material was FeSe.

[0043] Test results: A standard four-electrode device was constructed using the EBL process, and resistance-temperature testing was performed. R - T (Test). Reference Figure 3 ,like Figure 3 As shown in (a). R - T Test results show that the FeSe standard four-electrode device achieved a superconducting transition at low temperatures and exhibited zero resistance in the superconducting state, proving its superconductivity. However, AES single-point test results show that the Se content on the sample surface after transfer is significantly higher than that of Fe (…). Figure 3 (b) Sputter depth analysis further showed that with the extension of sputtering time, the Fe content inside the sample gradually increased and remained relatively constant, with an internal Fe / Se ratio close to 1.2:1. Figure 3 (c) and (d)). This indicates that despite surface oxidation and Se enrichment, the sample still undergoes a superconducting transition due to the relatively ideal internal Fe / Se ratio. Although the FeSe standard four-electrode device obtained through the EBL process still exhibits a relatively ideal... R - T The curve, but under a more subtle external magnetic field R - T During the tests, it was found that surface damage to the sample had a significant impact on the intrinsic two-dimensional superconducting properties of FeSe.

[0044] Example 1 This embodiment prepares a metastable two-dimensional material device. The steps of the preparation method are as follows: The first step is to place the MMI film on the support plate of the laser micro-cutting system, and then use the laser micro-cutting system to laser-cut and pattern the PET film on the MMI film.

[0045] The second step involves placing the mica substrate with the two-dimensional material grown on it against the mask. PMMA is then applied to two corners of the mica substrate, which is then attached to the mask to secure the mica. The relative position of the sample and the channel is observed using an optical microscope, and the position of the mica substrate is finely adjusted using tweezers to align the target sample with the device.

[0046] The third step involves placing the mask containing the sample into a vapor deposition machine for mask vapor deposition, and thermally depositing Au / Ag to complete the fabrication of the metastable two-dimensional material device (two-electrode device). The metastable two-dimensional material is FeSe.

[0047] Test results: refer to Figure 4 The resistance of this FeSe metastable two-dimensional material device monotonically decreases with decreasing temperature, undergoing a tetragonal to orthorhombic phase transition around 60 K. Further measurements of the sample...T c onset = 5.2 K, T c zero = 4.6 K ( T c onset and T c zero See definition Figure 4 a), △ T = 0.6 K, indicating that the sample exhibits good superconductivity. The two-dimensional superconductivity of this FeSe metastable two-dimensional material device was demonstrated by testing the superconductivity of a standard FeSe four-electrode device under magnetic fields perpendicular / parallel to the sample's ab plane, such as... Figure 4 As shown in b, as the applied vertical magnetic field gradually increases from 0 T to 9 T, the superconducting transition temperature of the sample decreases and eventually disappears. Figure 4 As shown in Figure c, as the applied parallel magnetic field gradually increases from 0 T to 9 T, the superconducting transition temperature of the sample increases from... T c zero = ~4.6 K(0 T) significantly decreased to T c zero = ~2.8 K (9 T), but did not completely disappear. It is evident that the superconductivity of this FeSe metastable two-dimensional material device is more resistant to parallel magnetic fields compared to a perpendicular magnetic field, indicating that the FeSe metastable two-dimensional material device possesses two-dimensional superconducting characteristics. Further analysis, such as... Figure 4 Figure d shows the change of magnetic field strength with temperature. H c2 - T / T c The curve of ) under a vertical magnetic field H c2⊥ and T / T c It exhibits clear linear behavior, which is consistent with the linear Ginzburg–Landau (GL) theory.

[0048] refer to Figure 5To avoid the irreversible effects of transfer and EBL processes on FeSe metastable two-dimensional material devices, which would make it difficult to measure the intrinsic superconductivity of FeSe, the method proposed in this application is used to fabricate FeSe two-electrode devices using a relatively non-destructive in-situ masking method. To demonstrate that the in-situ masking process is relatively non-destructive, the FeSe metastable two-dimensional material device on the mica surface was characterized by AES to confirm its initial surface oxidation state. A portion of Au was coated onto the mica substrate and the surface of the FeSe metastable two-dimensional material device using a local masking method. Figure 5 (b, c illustrations) makes the mica substrate, which should be insulating, conductive. AES single-point testing shows that the Fe / Se ratio on the sample surface is close to 1:1 (…). Figure 5 a) indicates that no obvious amorphous Se precipitation behavior was observed on the sample surface after in-situ masking. The depth analysis results also show that the Fe / Se ratio of the FeSe sample after masking is relatively stable, close to 1:1. The subsequent continuous increase in the Fe / Se ratio with the extension of sputtering time is due to the fact that the sample has been completely sputtered, resulting in insulation and charging at the sample position. At this time, the results are not accurate. Figure 5 c).

[0049] In addition, refer to Figure 6 The Fe / Se atomic ratios on the surfaces of FeSe two-electrode devices fabricated by wet transfer and in-situ masking methods were statistically analyzed using AES. The Fe / Se ratios on the FeSe surfaces after the two fabrication processes were also statistically analyzed using AES. The Fe / Se ratio on the FeSe surface of the in-situ masked device was significantly closer to the theoretical value of 1:1; therefore, the measured superconductivity of FeSe was closer to the intrinsic superconductivity of FeSe. Figure 7 Superconductivity testing of FeSe two-electrode devices. This paper describes the testing and investigation of two-dimensional superconductivity in two-dimensional tetragonal FeSe metastable two-dimensional material devices fabricated using the deposition method described in this application. For example... Figure 7 As shown in figure a, the superconducting transition temperature of metastable two-dimensional material devices. T c onset The resistance is 4.6 K, and it drops to zero at ~3.7 K, Δ T = 0.9 K, indicating its excellent superconductivity. Furthermore, the superconducting transition of the FeSe sample under perpendicular and parallel magnetic fields was measured as a function of the magnetic field. See [link to relevant documentation] Figure 7 The results showed that the upper critical field under the parallel magnetic field was significantly higher than that under the vertical magnetic field, further verifying the two-dimensional superconducting properties of the sample. H c2 - T / T c zero Data shows that under a vertical magnetic fieldH c2 - T / T c zero A linear relationship is observed, and the fitting results are obtained. H c2⊥ (0 K)≈ 3.58 T; while under a parallel magnetic field H c2 - T / T c zero It conforms to a quadratic relationship, and the fitting yields... H c2|| (0 K)≈ 15.93 T. Calculations yielded a FeSe device with an 8 nm thickness. ξ GL = 9.57 nm, d sc = 7.45 nm, close to the thickness of FeSe ( d = ~8 nm), and smaller than the coherence length of metastable two-dimensional material devices. ξ GL This further demonstrates the two-dimensional superconducting properties of FeSe metastable two-dimensional material devices.

[0050] Comparative Example 2 Comparative Example 2 is the same as Comparative Example 1, using the EBL process to construct a standard four-electrode device, and the metastable two-dimensional material is CuFeTe2.

[0051] Test Results: Reference Figure 8 The CuFeTe2 devices fabricated by the transfer and EBL processes were tested. R (1.8K) / R (300K) as high as 115.1. This comparative result indicates that CuFeTe2 samples with a thickness of <10 nm after transfer and EBL processing are difficult to maintain their intrinsic properties.

[0052] Example 2 Example 2 is the same as Example 1, except that the material of the metastable two-dimensional material device is CuFeTe2.

[0053] Test results: The intrinsic properties of a standard four-electrode device with a thickness of <10 nm were obtained through testing. R - TThe curves show that a two-electrode device for CuFeTe2 was fabricated using the method proposed in this application, with metallic silver (Ag) selected as the electrode material. Compared to EBL, the method of this application avoids damage to the sample caused by processes such as transfer, exposure, and vapor deposition. Because the melting point of metallic Ag is lower than that of Au, vapor deposition can be performed at a lower temperature, thereby reducing the thermal effects during the deposition process and avoiding irreversible damage to the CuFeTe2 sample. Through these optimizations, a metastable two-dimensional CuFeTe2 material device with a thickness of only 6.5 nm was successfully measured. R - T curve( Figure 9 ), T 1 is d R The temperature corresponding to / dT being 0, as... T SDW The transition temperature, T 2 is Figure 3 .33c in d R / d T - T The inflection point of the curve corresponds to a temperature at 325 K where a metallic-to-semiconductor transition occurs, indicating the SDW transition temperature of this sample. T SDW Approximately 325 K. Through analysis of... R - T The curve is differentiated to obtain d R / d T - T The curve further validated this. T SDW For approximately 325 K (see Figure 9 c). It is evident that even with a thickness less than 10 nm, the metastable two-dimensional CuFeTe2 material device still exhibits the SDW transition. The device fabricated using the method described in this application was tested... R (1.8K) / R (300K) is only 1.84. Therefore, the method of this application can better maintain its intrinsic properties compared with the device fabricated by EBL in Comparative Example 2.

[0054] Examples 3-7 Examples 3-7 are consistent with Example 2, except that the metastable two-dimensional material device is a Hall six-electrode device, and the thickness of the examples differs. See details below. Figure 10 .

[0055] Test results: The intrinsic properties of two-dimensional CuFeTe2 samples of different thicknesses were obtained by testing. R - T curve( Figure 10 ae). Statistical analysis was conducted on the relationship between SDW transition temperature and sample thickness ( Figure 10f), it was found that as the sample thickness increased, T SDW Gradually increasing. It is worth noting that the thickness of samples >20 nm... T SDW Clearly superior to existing technologies T SDW The prepared CuFeTe2 metastable two-dimensional material device has high crystal quality and ideal elemental composition.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for fabricating metastable two-dimensional material devices, characterized in that, The method includes the following steps: A patterned laser cutting process is performed on a polyethylene terephthalate film to obtain a photomask. A substrate is disposed on one side surface of the mask plate, and a portion of the substrate facing the mask plate has a metastable two-dimensional material layer. The metastable two-dimensional material layer is located within the orthogonal projection area of ​​the cutout area of ​​the mask plate onto the substrate, thus obtaining an intermediate body. The intermediate is subjected to vapor deposition, and the vapor deposition gas passes through the hollow area of ​​the mask plate and is deposited on the substrate to form an electrode, thereby obtaining the metastable two-dimensional material device.

2. The method according to claim 1, characterized in that, The hollowed-out area includes a first hollowed-out area and a plurality of second hollowed-out areas arranged radially around the first hollowed-out area and connected to the first hollowed-out area. The metastable two-dimensional material layer is located within the orthographic projection area of ​​the first hollowed-out area of ​​the mask on the substrate.

3. The method according to claim 1, characterized in that, The metastable two-dimensional material includes FeSe and FeS. x Se y Te 1-x-y At least one of CuFeTe2.

4. The method according to claim 1, characterized in that, The substrate material includes at least one of mica, sapphire, Si, and SiO2.

5. The method according to any one of claims 1-4, characterized in that, The vapor deposition gas contains at least one of Au and Ag.

6. The method according to any one of claims 1-4, characterized in that, The method further includes fixing the substrate to one side surface of the mask plate using an adhesive.

7. The method according to claim 6, characterized in that, The adhesive includes polymethyl methacrylate.

8. The method according to any one of claims 1-4, characterized in that, The minimum width of the patterned laser cutting process is 1μm-2μm; Optionally, the method further includes performing the patterned laser cutting process using a laser micro-cutting system.

9. A metastable two-dimensional material device prepared by the method according to any one of claims 1-8.

10. The metastable two-dimensional material device according to claim 9, characterized in that, The metastable two-dimensional material device includes at least one of the following: a Hall six-electrode device, a Hall four-electrode device, a standard four-electrode device, and a two-electrode device.

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