Synthesis method of two-dimensional transition metal chalcogenide based on co-sputtering technology

Abstract

The invention provides a two-dimensional transition metal chalcogenide (TMDs) synthesis method based on a co-sputtering technology, and aims to solve the bottlenecks in the aspects of low-temperature controllable synthesis, wafer-level uniformity, accurate layer number regulation and control and industrial expandability in the prior art. The method comprises the following steps: heating a transition metal compound to a reaction temperature, and carrying out co-sputtering reaction in an inert gas environment by taking an X element (Te, Se) and an M element (Pd, Pt, Bi, Mo, W, Ti) simple substance as target materials to realize low-temperature (llt; and wafer-level uniform growth of the high-purity TMDs thin film at 400 DEG C is realized. The number of layers and the stoichiometric ratio of the product can be accurately controlled by regulating and controlling the target material combination and sputtering parameters, the flexible substrate and the rigid substrate are compatible, and the subsequent transfer process is simplified. In addition, the method is simple in reaction condition, has industrial application potential, and is suitable for the fields of semiconductor devices, photoelectric devices, energy storage and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of two-dimensional material preparation, and particularly relates to a synthesis method of two-dimensional transition metal dichalcogenides (TMDs) based on co-sputtering technology, which is applicable to fields such as semiconductor devices, optoelectronic devices, and energy storage. Background Art

[0002] Two-dimensional (2D) transition metal dichalcogenides (TMDs), such as WSe 2 , WS 2 , MoSe 2 , MoSe 2 , PtSe 2 and PdSe 2 , have attracted extensive research interest globally since the exfoliation of graphene in 2004. These 2D TMDs possess various highly attractive optical and optoelectronic properties, including tunable bandgaps, high surface quality, excellent mechanical flexibility, and outstanding carrier mobility. Notably, the layers of 2D TMDs are bound by van der Waals forces. These weak van der Waals interactions, combined with the absence of surface dangling bonds, are conducive to the construction of heterojunctions. There are multiple types of TMDs with similar structures, and their basic chemical formula is MX 2 , where M is a transition metal atom and X is a chalcogen atom. The bandgap of TMDC can be adjusted by changing the number of layers or the thickness of the material, which enables its extensive research and application in the field of optoelectronic devices.

[0003] Currently, a variety of techniques have been developed to prepare TMDs, including chemical vapor deposition, molecular beam epitaxy, wet chemical methods, topological transformation methods, etc. However, chemical vapor deposition (CVD) requires high temperatures (>700 °C) and a chalcogen element vapor environment, and has problems such as low yield (monolayer rate < 30%), wide layer number distribution (1 - 10 layers), and poor substrate compatibility. Molecular beam epitaxy (MBE) requires an ultra-high vacuum environment, has high equipment costs, and it is difficult to achieve wafer-scale uniform growth. Wet chemical methods: impurities are easily introduced, and it is difficult to precisely control the number of product layers (such as uneven thickness of nanosheets), which is not conducive to device integration. Topological transformation methods: etching of MAX phase precursors is required, the steps are complex, and the performance of the product is easily deteriorated due to residues between layers. Existing methods have significant bottlenecks in low-temperature controllable synthesis, wafer-scale uniformity, precise layer number regulation, and industrial scalability.

[0004] For example:

[0005] Chinese Patent Application CN119041015A discloses an improved chemical vapor transport method for synthesizing two-dimensional metal tellurides and two-dimensional metal tellurides.

[0006] Chinese Patent Application CN116443933B discloses a method for synthesizing a modified two-dimensional molybdenum disulfide nanomaterial. This method prepares a carbon nanotube film / graphene and graphene / monolayer molybdenum disulfide double heterojunction on a PET substrate. This method has the characteristics of being able to produce modified monolayer or few-layer two-dimensional molybdenum disulfide, low cost, and mass production.

[0007] Chinese Patent Application CN117383520A discloses a method for synthesizing a two-dimensional tellurium selenide heterojunction based on a two-dimensional tellurium template method. More importantly, this method has the characteristics of low temperature and low pressure, simple operation, low cost, and being convenient for industrialization. And this two-dimensional tellurium selenide heterojunction can greatly improve the photoelectric detection performance of two-dimensional tellurene itself.

[0008] However, in the above disclosed preparation methods, large-area industrial production, precise control of the film layer number, precise element ratio, etc. cannot be achieved.

[0009] Therefore, how to prepare large-area and high-quality two-dimensional transition metal chalcogenides with few layers or a single layer to meet the applications of current microelectronics technology is an urgent problem to be solved. Summary of the Invention

[0010] The object of the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for synthesizing two-dimensional transition metal chalcogenides based on co-sputtering technology, including the steps of:

[0011] Heating step: In an inert gas environment, heat the transition metal compound to the reaction temperature;

[0012] Co-sputtering reaction step: Use elemental X (Te, Se) and elemental M (transition metal chalcogenides: Pd, Pt, Bi, Mo, W, Ti) as targets respectively for co-sputtering, and keep annealing for 1 h to obtain two-dimensional metal chalcogenides on the substrate surface;

[0013] In some embodiments, the targets are selected from one or more of Te, Se, Pd, Pt, Bi, Mo, W, and the sputtering power of the targets is 5 - 15 W.

[0014] In some embodiments, the sputtering pressure of the targets is 1 Pa, the sputtering time is 10 s to 300 s, and the sputtering temperature is 200 °C to 500 °C.

[0015] In some embodiments, the substrate includes Si, SiO 2 、Al 2 O 3 、NaCl, mica sheets, etc.

[0016] In some embodiments, the two-dimensional transition metal chalcogenides include: PdTe 2, PtTe 2 , PdSe 2 , PtSe 2 , MoTe 2 , WTe 2 , Bi 2 Te 3 , Bi 4 Te 5 .

[0017] In some embodiments, the two-dimensional transition metal chalcogenide is in a hexagonal or monoclinic structure; the lateral dimension of the two-dimensional material ranges from 1 μm to 1 mm, the thickness of the two-dimensional material ranges from 0.5 nm to 30 nm, and the number of layers ranges from 1 to 60 layers.

[0018] In some embodiments, the use of the two-dimensional transition metal chalcogenide in transistors, logic circuits, and sensors.

[0019] The present invention provides a method for synthesizing two-dimensional TMDs based on co-sputtering technology, aiming to solve the following problems:

[0020] (1) Achieve wafer-level uniform growth of low-temperature (<400 °C), high-purity TMDs thin films.

[0021] (2) Through target material combination and sputtering parameter regulation, precisely control the number of product layers (single layer to multi-layer) and stoichiometric ratio.

[0022] (3) Be compatible with flexible substrates (such as polyimide) and rigid substrates (such as SiO 2 / Si), and simplify the subsequent transfer process.

[0023] The advantages of the present invention are:

[0024] (1) In the present invention, based on single-element target materials, two-dimensional transition metal chalcogenides are obtained through reactions in co-sputtering technology. This reaction can highly react and has advantages such as high yield;

[0025] (2) The two-dimensional transition metal chalcogenides obtained by the synthesis method of the present invention are generated based on van der Waals (vdW) epitaxy. In this epitaxy method, the stacking of 2D vdW materials and three-dimensional (3D) substrates enables the target material to grow epitaxially on any 3D substrate through vdW epitaxy, thus eliminating the requirement of lattice matching. During the vdW epitaxy process, the weak vdW force between the vdW material and the epitaxial material allows relaxation of the mismatch strain, thereby reducing the defect density. In addition, the low surface energy and high migration coefficient of two-dimensional vdW materials are beneficial for anisotropic growth, thus growing the required two-dimensional materials.

[0026] (3) The synthesis method of the present invention can effectively reduce the reaction temperature and achieve the low-temperature growth of two-dimensional materials to meet the requirements of microelectronic processes because the magnetron sputtering technology can provide energy for atoms.

[0027] (4) The reaction conditions in the synthesis method of the present invention are simple, and the reaction can be completed in a short time, showing the potential for industrial application. Description of the Drawings

[0028] Figure 1 Schematic diagram of the preparation of two-dimensional transition metal chalcogenides by co-sputtering technology;

[0029] Figure 2 Physical picture of the co-sputtering technology;

[0030] Figure 3 Physical picture of depositing two-dimensional transition metal chalcogenides (PdTe 2 ) on the NaCl substrate in the embodiment;

[0031] Figure 4 XRD pattern of PdTe 2 generated by co-sputtering technology in the embodiment;

[0032] Figure 5 Raman spectrum of PdTe 2 generated by co-sputtering technology in the embodiment;

[0033] Figure 6 TEM image of PdTe 2 generated by co-sputtering technology in the embodiment;

[0034] Figure 7 SAED spectrum of PdTe 2 generated by co-sputtering technology in the embodiment;

[0035] Figure 8 IT response of the photodetector of PdTe 2 generated by co-sputtering technology in the embodiment;

[0036] Figure 9 PtTe 2 generated by co-sputtering technology in the embodiment;

[0037] Figure 10 PtSe 2 generated by co-sputtering technology in the embodiment. Detailed Description of the Invention

[0038] The present invention will be described in detail below with reference to the embodiments and the drawings.

[0039] Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0040] In the present invention, unless otherwise specified, all raw material components are commercially available products well-known to those skilled in the art.

[0041] The co-sputtering system used in the present invention has three target tables and can sputter with three different target materials.

[0042] The present invention provides a method for synthesizing two-dimensional transition metal chalcogenides based on co-sputtering technology, including the following steps:

[0043] (1) Place the substrate in the tray in the co-sputtering system, including Si, SiO 2 , Al 2 O 3 , NaCl, Mica, etc.

[0044] (2) Place the target materials in the target tables in the co-sputtering system, including Te, Se, Pd, Pt, Bi, Mo, W, etc.

[0045] (3) Place the tray in the vacuum chamber and evacuate the vacuum chamber to 5×10 -4 Pa. In the present invention, the temperature is preferably 300 - 500 °C. In the present invention, the pressure of the magnetron sputtering is preferably 0.4 - 1.0 Pa. In the present invention, the co-sputtering power is preferably 5 W - 15 W. In the present invention, the co-sputtering time is 5 s - 300 s.

[0046] (4) The present invention also provides the application of PdTe 2 thin film as a photodetector.

[0047] Example 1

[0048] A co-sputtering preparation method for a high-quality large-area PdTe 2 thin film, sputtering Pd and Te through a Pd target and a Te target on a substrate, and obtaining PdTe 2 after annealing treatment.

[0049] The co-sputtering preparation method for the PdTe 2 thin film of the present invention includes the following steps:

[0050] Place the single-side polished Al 2 O 3 (C-plane biased M-axis, surface roughness Ra < 3 Å) and NaCl on the rotatable substrate holder in the vacuum co-sputtering instrument. The process schematic diagram of the co-sputtering instrument is as shown in Figure 1 shown, and the physical diagram is as shown in Figure 2 shown.

[0051] Place the Te target on the first target stage and the Pd target on the second target stage. The purity of both targets is 99.99%. The angles between the first target stage and the second target stage and the substrate are both 45°, and the distance is adjusted to 2 mm. Then, pump the air pressure in the magnetron sputtering equipment chamber to 5×10 -4 Pa, introduce 35 sccm of Ar gas, adjust the size of the gate valve to 25%, and control the sputtering gas pressure in the vacuum chamber to 1 Pa. The substrate rotates at a speed of 10 rpm to ensure the uniform composition of the deposited film. Control the sputtering power of Te to be 10 W; the sputtering power of Pd to be 5 W. And heat the substrate temperature to 400 °C. Pre-sputter for 100 s first. Finally, open the sample baffle to allow Te and Pd particles to be uniformly deposited on the substrate. After sputtering for 100 s, close the sample baffle to obtain PdTe 2 film. Among them, the thickness of PdTe 2 is 10 nm, and both Pd and Te are sputtered by DC sputtering.

[0052] Close the gate valve, open the intake valve and the stop valve, and introduce 102 sccm of Ar gas. Keep the temperature at 400 °C for 60 min, and then let it cool naturally after the heat preservation ends. Finally, obtain PdTe 2 film. The PdTe 2 film obtained in this invention has an atomic ratio of about 1.9 - 2.1.

[0053] After depositing a substrate film on the Al 2 O 3 substrate, deposit a layer of Pd electrode on it to form a photodetector.

[0054] In Example 1, the physical diagram of depositing two-dimensional transition metal chalcogenide (PdTe 2 ) on the NaCl substrate is as shown in Figure 3 .

[0055] Perform XRD analysis on the PdTe 2 film prepared in Example 1. Its XRD pattern is as shown in Figure 4 .

[0056] Perform Raman analysis on the PdTe 2 film prepared in Example 1. Its Raman pattern is as shown in Figure 5 .

[0057] Figure 6 This is the surface TEM test of PdTe 2 . It can be seen from the figure that the clear arrangement of Pd and Te. Its crystal structure is hexagonal system. Figure 7 This is PdTe 2Selected area electron diffraction pattern. The sharp diffraction pattern at the grain boundary junction and the perfect atomic arrangement between the grain boundaries were confirmed by selected area electron diffraction and TEM images, which is consistent with the previous XRD results.

[0058] Figure 8 is PdTe 2 The optical response of the thin film under a 1550 nm laser can be seen to have a stable and good optical response curve.

[0059] The above results show that we effectively generated high-quality large-area PdTe 2 thin film in Example 1 and has leading performance in photodetectors.

[0060] Example 2

[0061] A method for co-sputtering the preparation of high-quality large-area PdTe 2 thin film, Pd and Te are co-sputtered on the substrate through Pd target and Te target, and PdTe 2 .

[0062] The co-sputtering preparation method of PdTe 2 thin film of the present invention includes the following steps:

[0063] Put the single-side polished Al 2 O 3 (C-plane is biased towards the M-axis, surface roughness Ra < 3 Å) and NaCl on the rotatable middle substrate holder of the vacuum co-sputtering instrument. The process schematic diagram of the co-sputtering instrument is as Figure 1 shown, and the physical diagram is as Figure 2 shown.

[0064] Place the Te target on the first target stage and the Pd target on the second target stage. The purity of the target materials is 99.99%; and the angle between the first target stage and the second target stage and the substrate is 45°, and the distance is adjusted to 2 mm; then pump the pressure in the chamber of the magnetron sputtering equipment to 5×10 -4 Pa, introduce 35 sccm of Ar gas, adjust the size of the gate valve to 25%, and control the sputtering pressure in the vacuum chamber to 1 Pa; the substrate rotates at a speed of 10 rpm to ensure the uniform composition of the deposited thin film. Control the sputtering power of Te to be 10 W; the sputtering power of Pd to be 5 W. And heat the substrate temperature to 300 °C. First pre-sputter for 100 s. Finally, open the sample baffle to allow Te and Pd particles to be uniformly deposited on the substrate. After sputtering for 100 s, close the sample baffle to obtain PdTe 2 thin film. Among them, the thickness of PdTe 2 is 10 nm, and both Pd and Te use DC sputtering.

[0065] Close the gate valve, open the intake valve and the stop valve, and introduce 102 sccm of Ar gas. Keep the temperature at 300 °C for 60 min, and then let it cool naturally. Finally, PdTe is obtained. 2 thin film.

[0066] Detected by XRD, the crystallization quality of the PdTe2 thin film prepared at 300 °C is inferior to that prepared at 400 °C.

[0067] Example 3

[0068] A method for co-sputtering to prepare a high-quality large-area PdTe 2 thin film, where Pd and Te are co-sputtered on a substrate through a Pd target and a Te target, and PdTe is obtained after annealing treatment. 2 .

[0069] The method for co-sputtering to prepare the PdTe 2 thin film of the present invention includes the following steps:

[0070] Place the single-side polished Al 2 O 3 (C-plane is biased towards the M-axis, and the surface roughness Ra < 3 Å) and NaCl on the rotatable middle substrate bracket of the vacuum co-sputtering instrument. The process schematic diagram of the co-sputtering instrument is as shown in Figure 1 shown, and the physical diagram is as shown in Figure 2 shown.

[0071] Place the Te target on the first target stage, and place the Pd target on the second target stage. The purity of the target materials is 99.99%; and the angle between the first target stage and the second target stage and the substrate is 45°, and the distance is adjusted to 2 mm; then pump the air pressure in the magnetron sputtering equipment chamber to 5×10 -4 Pa, introduce 35 sccm of Ar gas, adjust the size of the gate valve to 25%, and control the sputtering air pressure in the vacuum chamber to 1 Pa; rotate the substrate at a speed of 10 rpm to ensure the uniform composition of the deposited thin film. Control the sputtering power of Te to be 10 W; the sputtering power of Pd to be 5 W. And heat the substrate temperature to 500 °C. Pre-sputter for 100 s first. Finally, open the sample baffle to allow the Te and Pd particles to be uniformly deposited on the substrate. After sputtering for 100 s, close the sample baffle to obtain PdTe 2 thin film. Among them, the thickness of PdTe 2 is 10 nm, and both Pd and Te use DC sputtering.

[0072] Close the gate valve, open the intake valve and the stop valve, and introduce 102 sccm of Ar gas. Keep the temperature at 300 °C for 60 min, and then let it cool naturally. Finally, PdTe is obtained. 2 thin film.

[0073] The PdTe2 thin film prepared at 500 °C has a lower crystallization quality than that prepared at 400 °C as detected by XRD.

[0074] Example 4

[0075] A method for co-sputtering the preparation of a high-quality large-area PtTe 2 thin film, in which Pt and Te are co-sputtered on a substrate through a Pt target and a Te target, and PtTe is obtained after annealing treatment 2 .

[0076] The method for co-sputtering the preparation of the PtTe 2 thin film of the present invention includes the following steps:

[0077] Place the single-side polished Al 2 O 3 (C-plane is biased towards the M-axis, and the surface roughness Ra < 3 Å) on the rotatable substrate holder of the vacuum co-sputtering instrument.

[0078] Place the Te target on the first target stage and the Pt target on the second target stage. The purity of the targets is 99.99%; and the angles between the first target stage and the second target stage and the substrate are 45°, and the distance is adjusted to 2 mm; then evacuate the pressure in the chamber of the magnetron sputtering equipment to 5×10 -4 Pa, introduce 35 sccm of Ar gas, adjust the size of the gate valve to 25%, and control the sputtering pressure in the vacuum chamber to 1 Pa; rotate the substrate at a speed of 10 rpm to ensure the uniformity of the components of the deposited thin film. Control the sputtering power of Te to be 12 W; the sputtering power of Pt to be 5 W. And heat the substrate temperature to 400 °C. Pre-sputter for 100 s first. Finally, open the sample baffle to allow the Te and Pt particles to be evenly deposited on the substrate. After sputtering for 100 s, close the sample baffle to obtain the PtTe 2 thin film. Among them, the thickness of the PtTe 2 is 10 nm, and both Pt and Te are sputtered by DC sputtering.

[0079] Close the gate valve, open the intake valve and the stop valve, and introduce 102 sccm of Ar gas. Keep warm at 400 °C for 60 min, and let it cool naturally after the heat preservation ends, and finally obtain the PtTe 2 thin film.

[0080] Perform XRD analysis on the PtTe 2 thin film prepared in Example 2 of this embodiment, and its XRD pattern is as Figure 9 shown.

[0081] Example 5

[0082] A method for co-sputtering the preparation of a high-quality large-area PtSe 2Co-sputtering preparation method of thin film, Pt and Se are co-sputtered on a substrate through a Pt target and a Se target, and PtSe is obtained after annealing treatment 2 。

[0083] The PtSe of the present invention 2 Co-sputtering preparation method of thin film, comprising the following steps:

[0084] Put the single-side polished Al 2 O 3 (C-plane is biased towards the M-axis, surface roughness Ra < 3 Å) on the rotatable substrate holder of a vacuum co-sputtering instrument.

[0085] Place the Se target on the first target stage, and place the Pt target on the second target stage. The purity of the targets is 99.99%; and the angle between the first target stage and the second target stage and the substrate is 45°, and the distance is adjusted to 2 mm; then pump the air pressure in the magnetron sputtering equipment chamber to 5×10 -4 Pa, introduce 35 sccm of Ar gas, adjust the size of the gate valve to 25%, and control the sputtering gas pressure in the vacuum chamber to 1 Pa; the substrate rotates at a speed of 10 rpm to ensure uniform composition of the deposited thin film. Control the sputtering power of Se to be 40 W; the sputtering power of Pt to be 20 W. And heat the substrate temperature to 400 °C. First pre-sputter for 100 s. Finally, open the sample baffle to allow Se and Pt particles to be evenly deposited on the substrate. After sputtering for 100 s, close the sample baffle to obtain PtSe 2 thin film. Among them, the thickness of PtSe 2 is 10 nm, Pt is sputtered by DC, and Se is sputtered by RF.

[0086] Close the gate valve, open the intake valve and the stop valve, and introduce 102 sccm of Ar gas. Keep the temperature at 400 °C for 60 min, and let it cool naturally after the heat preservation ends, and finally obtain PtSe 2 thin film.

[0087] Perform XRD analysis on the PtSe 2 thin film prepared in Example 3 of this embodiment, and its XRD pattern is as Figure 10 shown.

[0088] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments according to this embodiment without creative efforts, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A method for synthesizing two-dimensional transition metal chalcogenides based on co-sputtering technology, comprising the following steps: Heating step: heating the transition metal compound to a reaction temperature in an inert gas environment; Co-sputtering reaction steps: Use X element (Te, Se) and M element (transition metal chalcogenides: Pd, Pt, Bi, Mo, W, Ti) as targets, co-sputter, and maintain annealing for 1 hour to obtain two-dimensional metal chalcogenides on the substrate surface.

2. The method according to claim 1, characterized in that The target material is selected from one or more of Te, Se, Pd, Pt, Bi, Mo, and W, and the sputtering power of the target material is 5-15W.

3. The method according to claim 1, characterized in that The target material sputtering pressure is 1 Pa, the sputtering time is 10s to 300s, and the sputtering temperature is 200°C to 500°C.

4. The method according to claim 1, characterized in that The substrates mentioned include Si, SiO2, Al2O3, NaCl, mica sheets, etc.

5. The method according to claim 1, characterized in that The two-dimensional transition metal chalcogenides include: PdTe2, PtTe2, PdSe2, PtSe2, MoTe2, WTe2, Bi2Te3, and Bi4Te5.

6. The method according to claim 1, characterized in that The two-dimensional transition metal chalcogenide is a hexagonal, monoclinic structure; the lateral size of the two-dimensional material is between 1 μm and 1 mm, the thickness of the two-dimensional material is between 0.5 nm and 30 nm, and the number of layers is between 1 and 60.

7. The method according to claim 1, characterized in that The claimed two-dimensional transition metal chalcogenides are used in transistors, logic circuits, and sensors.

Images