Molar superlattice preparation method based on heavy ion radiation and TMDC molar superlattice

Abstract

The invention belongs to the technical field of photoelectric devices, and relates to a molar superlattice preparation method based on heavy ion radiation and a TMDC molar superlattice, and the method comprises the steps: carrying out the heavy ion radiation on a multi-layer TMDC material through heavy ions, and enabling the incident angle of the heavy ions to be perpendicular to the multi-layer TMDC material, or enabling the heavy ions to be incident at an inclined angle with the multi-layer TMDC material; heavy ion radiation is carried out under vacuum at room temperature, heavy ions uniformly reach the surface of the multi-layer TMDC material through a scanning magnet, and the micro-area interlayer rotation angle of the multi-layer TMDC material is changed through the heavy ion radiation to prepare the molar superlattice. According to the invention, the multi-layer TMDC material does not need to be mechanically stacked piece by piece, so that the preparation process is obviously simplified, large-area production of the multi-layer TMDC material can be realized, and good time stability is shown.

Description

Technical Field

[0001] The present invention relates to a method for preparing a moiré superlattice based on heavy ion radiation and a TMDC (Transition Metal Dichalcogenides) moiré superlattice, belonging to the technical field of optoelectronic devices. Background Art

[0002] A moiré superlattice is an artificial periodic structure constructed by precisely controlling the rotation angle or stacking order of two-dimensional materials. This unique structural design forms a periodic potential field modulation at the atomic scale, leading to a significant reconstruction of the electron wave function and thus giving rise to a series of novel quantum phenomena. As a frontier platform for condensed matter physics research, moiré superlattices have demonstrated unique value in the research of major scientific issues such as unconventional superconducting states, fractional quantum Hall effects, and moiré excitons.

[0003] In the initial stage of research, scientists mainly focused on moiré superlattices in the graphene system. Typical breakthrough discoveries occurred in the magic-angle twisted bilayer graphene system: when two layers of graphene are rotated relative to each other at a specific angle of about 1.1°, the formed moiré superlattice exhibits rich correlated electron states including superconducting states and Mott insulating states. These discoveries have greatly promoted the research process of strongly correlated physics.

[0004] Currently, the preparation of moiré superlattices still mainly adopts a technical route of mechanical stacking combined with angle control. However, this process has obvious limitations: on the one hand, nanoscale angle control requires extremely high operation precision; on the other hand, inevitable interface contamination during the transfer process will significantly affect the material properties. These technical bottlenecks severely restrict the large-scale preparation and application expansion of moiré superlattices. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a method for preparing a moiré superlattice based on heavy ion radiation and a TMDC moiré superlattice, which does not require piece-by-piece mechanical stacking of the TMDC moiré superlattice, significantly simplifies the preparation process, can achieve large-area production of the TMDC moiré superlattice, and exhibits good time stability.

[0006] To achieve the above purpose, the present invention proposes the following technical solution: A method for preparing a moiré superlattice based on heavy ion radiation, including: performing heavy ion radiation on a multi-layer TMDC material by heavy ions; the heavy ion radiation is carried out under room temperature vacuum, the heavy ions pass through a scanning magnet and uniformly reach the surface of the multi-layer TMDC material, and the micro-region interlayer rotation angle of the multi-layer TMDC material is changed by heavy ion radiation to prepare a moiré superlattice.

[0007] Furthermore, the heavy ion radiation is high-energy heavy ion radiation or low-energy heavy ion radiation.

[0008] Furthermore, the high-energy heavy ion radiation is high-energy Ta ions; the fluence of the high-energy ion radiation is 5×10 10 ions / cm 2 .

[0009] Furthermore, the low-energy heavy ion radiation is low-energy Xe ions, and the fluence of the low-energy ion radiation is 5×10 11 ions / cm 2 .

[0010] Furthermore, the incident angle of the heavy ions is perpendicular to the multi-layer TMDC material, or the heavy ions are incident at an inclined angle with respect to the multi-layer TMDC material.

[0011] Furthermore, the inclined angle is 10° - 85°.

[0012] Furthermore, the inclined angle is 15°.

[0013] Furthermore, the multi-layer TMDC material is a multi-layer SnSe2 material.

[0014] Furthermore, the moiré superlattice prepared by heavy ion radiation is hexagonal.

[0015] The present invention also discloses a TMDC moiré superlattice, which is prepared by using the method for preparing a moiré superlattice based on heavy ion radiation described in any one of the above.

[0016] The technical solution of the present invention has at least the following technical effects or advantages:

[0017] 1. By directly depositing energy in the multi-layer TMDC material through heavy ion radiation, the present invention disrupts the weak interlayer interaction in the micro-region, enabling the occurrence of twist coupling between layers within an extremely short time, without the need for complex step-by-step stacking procedures, thus significantly simplifying the process flow.

[0018] 2. The present invention can effectively avoid interface contamination and enhance the structural stability of the moiré superlattice.

[0019] 3. By adjusting parameters such as the energy, dose, and incident angle of the heavy ions, the present invention controls the energy deposition density and deposition path of the ions in the material, achieving effective control of the moiré twist angle and structural period.

[0020] 4. Heavy ion radiation can not only form a moiré periodic structure, but also synchronously introduce controllable doping or defect states. This characteristic enables the electronic structure and optical response to be synergistically regulated with the moiré superlattice, laying a foundation for the development of new quantum materials and functional devices. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the preparation method of the Moore superlattice based on heavy ion radiation in an embodiment of the present invention;

[0022] Figure 2 (a) is the TEM image of the initial multi-layer SnSe2 material; Figure 2 (b) is the inverse Fourier transform image of the initial multi-layer SnSe2 material, and the upper right inset in the figure is the selected area diffraction pattern;

[0023] Figure 3 (a) is the HRTEM (High Resolution Transmission Electron Microscope) image of the SnSe2 sample after 90° radiation of 600 keV Xe ions, Figure 3 (b) is the inverse Fourier transform corresponding to Figure 3 (a), Figure 3 (c) is the schematic diagram after the stacking of two atomic layers with a misalignment angle in the SnSe2 sample, Figure 3 (d), (e) are respectively Figure 3 the lattice structure diagrams corresponding to the two sets of diffraction spots in

[0024] Figure 4 (a) is the HRTEM image of SnSe2 after 15° radiation of 600 keV Xe ions, Figure 4 (b) is the inverse Fourier transform corresponding to Figure 4 (a), Figure 4 (c), (d) are respectively Figure 4 the lattice structures corresponding to the two sets of diffraction spots in

[0025] Figure 5 It is the surface morphology diagram of the material after irradiation with 500 keV Xe ions at a high fluence (1×10 13 ions / cm 2 );

[0026] Figure 6 It is the superlattice morphology diagram generated in multi-layer SnSe2 after the incidence of 5×10 10 ions / cm 2 high-energy Ta ions (2.1 GeV) at different angles, Figure 6 (a) is the HRTEM image formed by the vertical incidence of Ta ions on the SnSe2 material, Figure 6 (b) is the inverse Fourier transform corresponding to Figure 6 (a), and the twisting angles of the two sets of diffraction spots are marked in the inset; Figure 6 (c) is the HRTEM image formed by the 15° incidence of Ta ions on the SnSe2 material, Figure 6(d) is Figure 6 (c) corresponding inverse Fourier transform diagram, and the torsion angles of two sets of diffraction spots are marked in the illustration. Detailed implementation manners

[0027] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the provision of the specific implementation manners is only for better understanding of the present invention, and they should not be construed as limitations on the present invention. In the description of the present invention, it should be understood that the terms used are only for the purpose of description and cannot be construed as indicating or implying relative importance.

[0028] Transition Metal Dichalcogenides (TMDCs) have become an important platform for exploring new quantum phenomena due to their unique electronic structures and rich physical properties. For example, tin diselenide (SnSe2) has a high electron affinity of 4.5 - 5.5 eV and a theoretical carrier mobility of up to 436 cm 2 V -1 s -1 showing the potential for application in low-power tunnel transistors and high-speed electronic devices. In addition, the tunable bandgap range of this material is 1.25 - 3.5 eV. Combining its atomic-level thickness and dangling-bond-free structure provides new possibilities for the design of multi-band photodetectors and high-performance electronic devices. It is worth noting that the moiré superlattice structure based on TMDC materials has been proven to support the formation of quantum Wigner molecules, opening up more possibilities for quantum physics research.

[0029] The existing preparation of moiré superlattices mainly relies on mechanical stacking and rotation angle control, which has complex processes and is prone to contaminating the material interface. To solve the above problems, the present invention proposes a method for preparing a moiré superlattice based on heavy-ion radiation and a moiré superlattice, a method for generating a moiré superlattice in a multi-layer SnSe2 material by heavy-ion radiation. The present invention disrupts the weak interlayer interaction forces in the material micro-region through the local energy deposition caused by heavy-ion radiation in the SnSe2 material, causing small-angle deflections between layers to form a moiré superlattice of a van der Waals heterostructure. Compared with the traditional transfer method, this method is more stable, has controllable rotation angles, and is suitable for large-scale production. The method of the present invention does not require piece-by-piece mechanical stacking, significantly simplifies the preparation process, and can achieve large-area production, showing good time stability. In addition, the heavy-ion radiation technology can also achieve precise processing of localized superlattices and can be applied to the structural design of special-purpose structures such as quantum dots, providing a unique solution for the development of future quantum devices.

[0030] Example 1

[0031] This embodiment discloses a method for preparing a moiré superlattice based on heavy-ion radiation, including: irradiating a multi-layer TMDC material with heavy ions, where the incident ions are high-energy (2.1 GeV) Ta ions provided by the Lanzhou Heavy Ion Accelerator or 600 keV low-energy Xe ions provided by a 320 kV low-energy heavy-ion accelerator; the electronic energy loss of 2.1 GeV Ta ions on the surface of the SnSe2 material is 28.2 keV / nm, and the range is about 80.9 microns; the electronic energy loss of 600 keV low-energy heavy ions on the surface of the SnSe2 material is 0.7 keV / nm, the nuclear energy loss is 2.7 keV / nm, and the range is about 147 nanometers; the heavy-ion radiation is carried out at room temperature and in vacuum; the heavy ions pass through a scanning magnet and uniformly reach the surface of the multi-layer TMDC material; the incident angle of the heavy ions is perpendicular to the multi-layer TMDC material or incident at an inclined angle with respect to the multi-layer TMDC material. The energy deposition path of the inclined-incident ions in the material is longer than that of the perpendicular-incident path, and the thermal effect and distortion generated in the material are stronger. The interlayer twist angle and the moiré superlattice period can be regulated by adjusting the incident angle. As Figure 1 shown, by changing the incident angle of Ta ions from perpendicular incidence to inclined incidence at 10° - 85°, the twist angle of the moiré structure can be increased from 9° to 14°, and the period can be decreased from 1.33 nm to 1.00 nm. The radiation fluence of high-energy heavy ions (2.1 GeV Ta) is 5×10 10 ions / cm 2 , and the radiation fluence of low-energy heavy ions (600 keV Xe) is 5×10 11 ions / cm 2 . After the heavy ions reach the surface of the target material, by interacting with the atomic nuclei and extranuclear electrons of the material, the energy they carry is deposited in the target material, ultimately breaking the chemical bonds in the material, causing lattice distortion of the material, and even introducing defects. By using heavy-ion radiation to break the weak interlayer interaction force of the TMDC material and change the interlayer twist angle of the micro-region, a moiré superlattice is prepared, providing a reliable platform for advanced devices and quantum computing.

[0032] In this embodiment, the heavy ions are selected according to the material usage. For example, 2.1 GeV Ta ions or 600 keV Xe ions can be selected, but not limited thereto. As long as the heavy ions can cause lattice distortion of the material, they can be used. The number of layers of the multi-layer TMDC material is greater than or equal to two layers, preferably thicker, dozens of layers of TMDC materials, or it can also be a bulk TMDC material.

[0033] The heavy-ion radiation is high-energy heavy-ion radiation or low-energy heavy-ion radiation. The radiation fluence of high-energy ion radiation is 5×10 10 ions / cm 2 ; the radiation fluence of low-energy ion radiation is 5×10 11 ions / cm2 .

[0034] In this embodiment, the multi-layer TMDC material is exemplified by the multi-layer SnSe2 material for experiments. The high-energy ion radiation is GeV-level heavy ion radiation, and the low-energy ion radiation is keV-level heavy ion radiation.

[0035] To achieve in-situ observation of the microstructure after radiation, in this embodiment, the multi-layer SnSe2 materials without and with heavy ion radiation are respectively transferred to the positioning grids. The positioning grid is the grid used to place and position the sample during the HRTEM experiment. As Figure 2 (a) shows, the multi-layer SnSe2 material without heavy ion radiation has a perfect lattice, with the atoms arranged neatly and orderly. After measurement, the lattice spacing is 0.325 nm, which conforms to the (101ˉ) plane of SnSe2. As Figure 3 shown, Figure 3 is the microstructure of multi-layer SnSe2 after 600 keV Xe ion radiation. The radiation fluence is 5×10 11 ions / cm 2 . The ions are incident along the direction perpendicular to the material surface. An obvious moiré structure is observed in the field of view, and the measured period length is 1.32 nm. There are two sets of periodically arranged diffraction spots in the lattice diffraction pattern. After the two sets of diffraction points in Figure 3 (b) are processed by IFFT (inverse Fourier transform), the images in Figure 3 (d) and Figure 3 (e) are obtained respectively, and the twist angle is 10°. Figure 4 is the microstructure after 600 keV Xe ions are incident on the material at a 15° inclination angle. The radiation fluence is 5×10 11 ions / cm 2 . A large area of moiré lattice is found. The lattice is hexagonal, arranged neatly and regularly. The measured period length is 0.78 nm, and the twist angle is about 12°. It can be clearly found that as the angle between the incident ions and the material surface decreases, the moiré rotation angle increases, which corresponds to the obvious deposition of energy by the inclination angle on the material surface and the generation of a strong surface effect. Figure 5 is the micro-morphology after high fluence (1×10 13 ions / cm 2 ) 500 keV Xe ion radiation, as Figure 5 shown. The surface of the SnSe2 material shows a fish-scale-like morphology, further proving that the heavy ion radiation destroys the weak interlayer interaction force. High fluence heavy ion radiation can cause micro-region peeling of the layered material. Therefore, an appropriate ion incident fluence needs to be selected during the preparation process of the moiré superlattice. Figure 6 is for 5×10 10 ions / cm 2The superlattice morphology generated by high-energy Ta ions in multi-layer SnSe2 is as follows Figure 6 shown. As the incident angle decreases, the superlattice rotation angle increases, further proving that the method in this embodiment is applicable to both high-energy heavy ions and low-energy heavy ions.

[0036] Example 2

[0037] Based on the same inventive concept, this embodiment discloses a TMDC moiré superlattice prepared by using any one of the above-mentioned moiré superlattice preparation methods based on heavy ion radiation. The moiré superlattices generated by heavy ion radiation mostly exhibit regularly arranged hexagons. 600 keV Xe ions are perpendicularly incident on the multi-layer SnSe2 material with a fluence of 5×10 11 ions / cm 2 . The period length of its moiré structure is about 1.32 nm, and the twist angle is 10°; 600 keV Xe ions with the same fluence are incident on the multi-layer SnSe2 material at an inclination angle of 15°, and its moiré lattice is hexagonal, with a measured period length of 0.78 nm and a twist angle of about 12°. 5×10 10 ions / cm 2 High-energy (2.1 GeV) Ta ions are perpendicularly incident on the multi-layer SnSe2 material, and the moiré lattice is hexagonal, with a measured period length of 1.33 nm and a twist angle of about 9°; high-energy (2.1 GeV) Ta ions with the same fluence are incident on the multi-layer SnSe2 at an inclination angle of 15°, and the moiré lattice is hexagonal, with a measured period length of 1.00 nm and a twist angle of about 14°.

[0038] 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 them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement without departing from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention. The above content is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or replacements, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing a Moore superlattice based on heavy ion radiation, characterized in that, Including: Performing heavy-ion radiation on a multi-layer TMDC material by using heavy ions; The heavy-ion radiation is performed under room-temperature vacuum. The heavy ions pass through a scanning magnet and uniformly reach the surface of the multi-layer TMDC material. By means of the heavy-ion radiation, the interlayer rotation angle of the micro-region of the multi-layer TMDC material is changed to prepare a moiré superlattice.

2. The method for preparing a Moore superlattice based on heavy ion radiation according to claim 1, wherein, The heavy-ion radiation is high-energy heavy-ion radiation or low-energy heavy-ion radiation.

3. The method for preparing a Moore superlattice based on heavy ion radiation according to claim 2, wherein The high-energy heavy-ion radiation is high-energy Ta ions; the fluence of the high-energy ion radiation is 5×10 10 ions / cm 2 .

4. The method for preparing a Moore superlattice based on heavy ion radiation according to claim 2, characterized in that, The low-energy heavy-ion radiation is low-energy Xe ions, and the fluence of the low-energy ion radiation is 5×10 11 ions / cm 2 .

5. The method for preparing a Moore superlattice based on heavy ion radiation according to claim 1, characterized in that, The incident angle of the heavy ions is perpendicular to the multi-layer TMDC material or is incident at an inclination angle with respect to the multi-layer TMDC material.

6. The method for preparing a moiré superlattice based on heavy ion radiation according to claim 5, wherein The inclination angle is 10°-85°.

7. The method for preparing a Moore superlattice based on heavy ion radiation according to claim 6, wherein The inclination angle is 15°.

8. The method for preparing a Moore superlattice based on heavy ion radiation according to claim 1, wherein The multi-layer TMDC material is a multi-layer SnSe2 material.

9. The method for preparing a Moore superlattice based on heavy ion radiation according to claim 1, wherein The moiré superlattice prepared by heavy-ion radiation is hexagonal.

10. A TMDC moiré superlattice, characterized in that, Obtained by using the method for preparing a moiré superlattice based on heavy-ion radiation according to any one of claims 1-9.

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