Manipulation method for realizing phase change of two-dimensional TMD material

Abstract

The embodiment of the invention provides a manipulation method for realizing the phase change of a two-dimensional TMD material, and the method comprises the following steps: enabling an STM probe to be close to the two-dimensional TMD material through adjusting the tunneling current and / or bias voltage of an STM, and to be located at a position close to the vertex of a T-phase nanometer island of the two-dimensional TMD material; moving the STM probe along a specific track at a preset moving speed so as to enable the T-phase nano island of the two-dimensional TMD material to move; and enabling the T-phase nano island of the two-dimensional TMD material to mechanically collide with the adjacent H-phase nano island, so that the T-phase nano island is subjected to phase change, and a heterojunction structure of the T-phase nano island and the H-phase nano island is generated. According to the manipulation method for achieving the phase change of the two-dimensional TMD material, the two-dimensional TMD material is manipulated through the STM probe, mechanical collision is achieved, the phase change of the two-dimensional TMD material is induced, and therefore heterostructure construction can be achieved. The embodiment of the invention further provides the two-dimensional TMD material.

Description

Technical Field

[0001] This application belongs to the technical field of nanoscale material manufacturing, and particularly relates to a manipulation method for realizing the phase transition of two-dimensional TMD materials and two-dimensional TMD materials. Background Art

[0002] As two-dimensional quantum materials, transition metal dichalcogenides (TMDs) show application potential in multiple fields. Their multiple polycrystals, such as the trigonal prismatic phase (H phase) and the octahedral phase (T phase), coexist in the same sample, enabling the construction of atomically precise heterointerfaces with high versatility and flexibility in designing new atomic-scale electronic devices.

[0003] However, existing regulation strategies for TMDs phase transitions are diverse, including electrochemical intercalation strategies, thermodynamic regulation paths, out-of-plane electric field modulation techniques, and electron beam irradiation, etc. These methods have improved the ability to regulate and design TMDs, but there are obvious limitations: one is that they mainly target bulk material systems, with complex micro-nano processing techniques and difficulty in preparing high-performance micro-nano integrated devices; the second is that existing phase transition induction methods mostly rely on external stimuli such as ion implantation or voltage pulses, which are prone to interfering with adjacent functional structures during micro-nano scale processing; the third is the lack of precise regulation means for the electronic properties of heterojunction interfaces, making it difficult to achieve the directional design and performance optimization of interface energy band structures. These drawbacks limit the further development of TMDs in fields such as micro-nano electronic devices and urgently need new technical solutions to solve. Summary of the Invention

[0004] In view of the problems existing in the above related technologies, the embodiments of this application provide a manipulation method for realizing the phase transition of two-dimensional TMD materials and two-dimensional TMD materials. By manipulating the two-dimensional TMD materials with an STM probe, mechanical collision is achieved, inducing the two-dimensional TMD materials to undergo a phase transition, thereby enabling the construction of heterostructures.

[0005] In a first aspect, the embodiments of this application provide a manipulation method for realizing the phase transition of two-dimensional TMD materials, including the following steps:

[0006] By adjusting the tunneling current and / or bias voltage of the STM, the STM probe is brought close to the two-dimensional TMD material and positioned at a position adjacent to the vertex of the T-phase nanoisland of the two-dimensional TMD material;

[0007] Moving the STM probe along a specific trajectory at a preset moving speed so that the T-phase nanoisland of the two-dimensional TMD material moves; and

[0008] Cause the T-phase nanoislands of the two-dimensional TMD material to mechanically collide with adjacent H-phase nanoislands, so that the T-phase nanoislands undergo a phase change, generating a heterojunction structure of T-phase and H-phase nanoislands.

[0009] Further, after adjusting the tunneling current and / or bias voltage of the STM to bring the STM probe close to the two-dimensional TMD material, it further includes:

[0010] Position the STM probe at a position adjacent to the vertex of the T-phase nanoisland of the two-dimensional TMD material.

[0011] Further, the moving the STM probe along a specific trajectory at a preset moving speed to cause the T-phase nanoislands of the two-dimensional TMD material to move includes:

[0012] Move the STM probe along a specific trajectory at a preset moving speed to cause the T-phase nanoislands of the two-dimensional TMD material to perform a controlled rotation around the vertex while performing a translational motion.

[0013] Further, the T-phase nanoisland is a T-NbSe2 island, and the H-phase nanoisland is an H-NbSe2 island.

[0014] Further, before adjusting the tunneling current and / or bias voltage of the STM to bring the STM probe close to the two-dimensional TMD material and position it at a position adjacent to the vertex of the T-phase nanoisland of the two-dimensional TMD material, it further includes:

[0015] Prepare a two-dimensional TMD material with coexisting H-NbSe2 islands and T-NbSe2 islands on bilayer graphene epitaxially grown on a SiC substrate.

[0016] Further, the tunneling current of the STM is set to 1 nA, and the bias voltage is set to -0.1 V.

[0017] Further, the preset moving speed of the STM probe is 1 nm / s.

[0018] Further, the operating environment temperature of the STM probe is liquid helium temperature.

[0019] Further, the rotation angle of the T-phase nanoisland of the two-dimensional TMD material is calculated by measuring the angular displacement of the island edge before and after the rotation of the T-phase nanoisland.

[0020] In a second aspect, an embodiment of the present application provides a two-dimensional TMD material, which is made by the method described in any one of the above.

[0021] In the method for manipulating the phase transition of two-dimensional TMD materials provided by the embodiments of the present application, based on the interaction force between the STM probe and the surface of the two-dimensional TMD material, the STM probe is brought close to the surface of the two-dimensional TMD material by adjusting the tunneling current and / or bias voltage of the STM. Subsequently, the STM probe is moved along a specific trajectory at a preset speed to drive the movement of the T-phase nanodots. When the T-phase nanodots of the two-dimensional TMD material mechanically collide with the adjacent H-phase nanodots, the energy and stress field changes generated by the collision trigger the phase transition of some T-phase nanodots of the two-dimensional TMD material to the H-phase, and a heterojunction structure with coexistence of T-phase and H-phase nanodots is formed. Therefore, the method for manipulating the phase transition of two-dimensional TMD materials and the two-dimensional TMD materials provided by the embodiments of the present application can manipulate the two-dimensional TMD material through the STM probe to achieve mechanical collision, induce the phase transition of the two-dimensional TMD material, thereby enabling the construction of heterostructures. After the precise construction of the heterojunction is achieved through the phase transition, the precise design of the energy band structure at the interface can be realized, providing a new interface engineering strategy for customized electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0023] Figure 1 It is a schematic flow chart of the method for manipulating the phase transition of two-dimensional TMD materials provided by the embodiments of the present application;

[0024] Figure 2 It is a schematic diagram of the STM atomic resolution image of the single-layer H-NbSe2 and T-NbSe2 islands of the two-dimensional TMD material provided by the embodiments of the present application;

[0025] Figure 3 It is a schematic diagram of the process of realizing the controllable rotation of the T-NbSe2 island on the bilayer graphene (BLG) by the method for manipulating the phase transition of two-dimensional TMD materials provided by the embodiments of the present application;

[0026] Figure 4 It is a schematic diagram of the phase transition process of mechanically colliding and inducing the T-NbSe2 island to the H-NbSe2 island by the method for manipulating the phase transition of two-dimensional TMD materials provided by the embodiments of the present application.

[0027] The realization of the purpose of the present application, functional features and advantages will be further described in conjunction with the embodiments with reference to the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0029] It should be understood that when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0030] It should also be understood that the terms used in this specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this specification of the present application and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present application according to specific circumstances.

[0031] Referring to Figures 1 to 4 , the embodiments of the present application provide a method for manipulating the phase transition of two-dimensional TMD materials, including the following steps:

[0032] S101: By adjusting the tunneling current and / or the bias voltage of the STM, the STM probe is brought close to the two-dimensional TMD material and positioned at a position adjacent to the vertex of the T-phase nanoisland of the two-dimensional TMD material;

[0033] S102: Move the STM probe along a specific trajectory at a preset moving speed so that the T-phase nanoisland of the two-dimensional TMD material moves; and

[0034] S103: Make the T-phase nanoisland of the two-dimensional TMD material mechanically collide with an adjacent H-phase nanoisland so that the T-phase nanoisland undergoes a phase transition to produce a heterojunction structure of T-phase and H-phase nanoislands.

[0035] Specifically, based on the interaction force between the STM probe and the surface of the two-dimensional TMD material, the STM probe is brought close to the surface of the two-dimensional TMD material by adjusting the tunneling current and / or the bias voltage of the STM. Subsequently, the STM probe is moved along a specific trajectory at a preset speed to drive the movement of the T-phase nanoislands. When the T-phase nanoislands of the two-dimensional TMD material mechanically collide with the adjacent H-phase nanoislands, the change in energy and stress field generated by the collision triggers the phase transition of some T-phase nanoislands of the two-dimensional TMD material to the H-phase, and a heterojunction structure with coexistence of T-phase and H-phase nanoislands is formed. Therefore, the manipulation method for realizing the phase transition of the two-dimensional TMD material and the two-dimensional TMD material provided by the embodiments of the present application manipulate the two-dimensional TMD material through the STM probe to achieve mechanical collision, induce the phase transition of the two-dimensional TMD material, so as to be able to realize heterostructure construction. And after accurately constructing the heterojunction through the phase transition, the precise design of the energy band structure at the interface can be realized, and a new interface engineering strategy can be provided for customized electronic devices.

[0036] Further, in some embodiments of the present application, after bringing the STM probe close to the two-dimensional TMD material by adjusting the tunneling current and / or the bias voltage of the STM, it further includes:

[0037] Position the STM probe at a position adjacent to the vertex of the T-phase nanoisland of the two-dimensional TMD material.

[0038] Specifically, the vertex of the T-phase nanoisland of the two-dimensional TMD material is its key part, and its microenvironment and electron state distribution are unique, which have a great influence on the subsequent movement, phase transition of the nanoisland and the interaction with the adjacent H-phase nanoisland. Precise positioning here can enable the STM probe to more effectively establish an interaction with the T-phase nanoisland, provide guarantee for the subsequent precise control of the movement and phase transition of the nanoisland, and is the basis for the smooth progress of the entire manipulation process. Relying on the high-precision positioning ability of the STM, combined with advanced image recognition technology and feedback control system. First, image and analyze the surface topography of the two-dimensional TMD material, accurately identify the position of the vertex of the T-phase nanoisland, then drive the STM probe to move to this position, and ensure the positioning accuracy reaches the nanometer or even sub-nanometer level with the help of real-time monitoring and precise adjustment.

[0039] Further, in some embodiments of the present application, moving the STM probe along a specific trajectory at a preset moving speed to cause the T-phase nanoislands of the two-dimensional TMD material to move includes:

[0040] Move the STM probe along a specific trajectory at a preset moving speed to cause the T-phase nanoislands of the two-dimensional TMD material to rotate controllably around the vertex and perform translational motion at the same time.

[0041] Specifically, there is an interaction force between the STM probe and the T-phase nanoisland. When the probe moves along a preset trajectory at a specific speed, this interaction force generates a torque that drives the nanoisland to rotate around the vertex. At the same time, the continuous movement of the probe also generates a driving force on the nanoisland, prompting it to translate. By precisely adjusting the movement speed and trajectory of the probe, fine control over the rotation angle, rotation speed, translation direction, and translation distance of the nanoisland can be achieved.

[0042] Furthermore, in some embodiments of the present application, the T-phase nanoisland is a T-NbSe2 island, and the H-phase nanoisland is an H-NbSe2 island.

[0043] Specifically, there are differences in crystal structure and physical properties between the T-NbSe2 island and the H-NbSe2 island. T-phase NbSe2 has unique characteristics such as an electronic energy band structure and charge density wave, and has potential application value in the fields of nanoelectronics, superconductivity, etc. The superconducting transition temperature, electron mobility, etc. of H-phase NbSe2 are different from those of the T-phase, providing a comparison sample for phase transition research and material property regulation.

[0044] Through STM probe manipulation, phase transition and the formation of heterojunction structures between the T-NbSe2 island and the H-NbSe2 island can be achieved, and further, the mutual transformation law of different phases and the influence of the heterojunction structure on material properties can be systematically studied.

[0045] From the perspective of application prospects, based on the precise manipulation of the phase transition of two-dimensional NbSe2 materials, nano-devices with specific properties can be developed. For example, the use of the heterojunction structure after phase transition to achieve efficient electron transport, superconducting property regulation, etc., provides new ideas and methods for the development of fields such as nanoelectronics and superconducting devices.

[0046] Furthermore, referring to Figure 2 , in some embodiments of the present application, before adjusting the tunneling current and / or bias voltage of the STM to make the STM probe approach the two-dimensional TMD material and locate at a position adjacent to the vertex of the T-phase nanoisland of the two-dimensional TMD material, it further includes:

[0047] Preparing a two-dimensional TMD material with coexisting H-NbSe2 islands and T-NbSe2 islands on bilayer graphene epitaxially grown on a SiC substrate.

[0048] Specifically, bilayer graphene can be epitaxially grown on a SiC substrate through molecular beam epitaxy (MBE) technology. This step provides a unique substrate environment for subsequent material growth and affects the growth and properties of two-dimensional TMD materials. Then, a two-dimensional TMD material with coexisting H-NbSe2 islands and T-NbSe2 islands is prepared on the bilayer graphene. Complex growth techniques such as chemical vapor deposition are used to precisely control the growth parameters to achieve the coexistence of NbSe2 islands in two phase states and reasonably control the size and distribution of the islands. This material system provides a basis for studying the phase transition mechanism and fabricating heterojunction structures.

[0049] After the material preparation is completed, subsequently, by adjusting the tunneling current and / or bias voltage of the STM, the STM probe can be brought close to the material and positioned at the apex of the T-phase nanoisland, and then a series of phase transition manipulation operations can be carried out. High-quality material preparation in the early stage is the guarantee for the smooth progress of subsequent operations. Only based on a good material foundation can the effective regulation of the properties of two-dimensional TMD materials be achieved, laying a foundation for the development of new nano-devices.

[0050] Refer to Figure 3 , Figure 3 FIG. is a schematic diagram of the process of realizing the controllable rotation of T-NbSe2 islands on bilayer graphene (BLG) achieved by the manipulation method for realizing the phase transition of two-dimensional TMD materials provided in the embodiment of the present application. In order to precisely control the mechanical collision between single-layer H-NbSe2 islands and single-layer T-NbSe2 islands, the embodiment of the present application adopts the technology of STM probe manipulation. The single-layer T-NbSe2 island is manipulated on the BLG by the STM probe, so that it can perform controllable rotation and translation movements on the BLG substrate. As shown in FIG. a in Figure 3 , to achieve precise rotation, first, the tunneling current and bias voltage are set to reduce the distance between the STM probe and the sample, then the STM tip is positioned near the apex of the NbSe2 island, and then the tip is moved along a specific trajectory (as shown by the arrow in FIG. a) at a preset moving speed, thereby inducing a controlled rotation of the T-phase NbSe2 island by an angle θ. FIGS. b to d show representative STM images of three T-phase NbSe2 islands on the BLG substrate before and after STM tip manipulation. When the STM probe approaches the apex of the T-phase NbSe2 island (marked by the arrow), the island can be rotated controllably around one of its vertices. Precise rotation of the NbSe2 island can be achieved by controlling the moving distance and direction of the STM probe. During the probe operation, the T-NbSe2 island can remain stable at any angle on the BLG, achieving the controllable rotation of the T-NbSe2 island on the BLG with atomic-level precision.

[0051] Refer to Figure 4 , Figure 4Schematic diagram of the phase transition process of mechanical collision-induced T-NbSe2 islands to H-NbSe2 islands realized by the method for manipulating the phase transition of two-dimensional TMD materials provided in the embodiments of the present application. Through the STM probe manipulation technology, it is possible to precisely control the mechanical collision between monolayer H-NbSe2 islands and T-NbSe2 islands with close positions on bilayer graphene (BLG). Figure 4 Figures a and b in Figure 4 respectively show the STM images before and after the mechanical collision. In Figure a, the morphology and position of the T-NbSe2 island before the collision can be seen. Move the STM tip along the direction of the arrow to manipulate the rotation of the T-NbSe2 island. Figure b shows the STM image after the mechanical collision between the H-NbSe2 island and the T-NbSe2 island. The dashed box marks the position of the island before the collision. Through analysis, it can be found that the T-NbSe2 island rotates around one of its vertices, and the adjacent H-NbSe2 island also shows a certain degree of displacement. It is worth noting that after the mechanical collision between the T-NbSe2 island and the H-NbSe2 island, some of the T-NbSe2 islands undergo a phase transition, turning into the H phase, and forming a heterojunction structure of T-phase and H-phase NbSe2 islands. This method of using the STM probe manipulation, which can push the TMD island to rotate around one of its vertices, can bring relatively high speed and energy. The local stress generated during the mechanical collision directly destroys the stability of the T phase, triggering its irreversible transformation to the H phase, thereby controllably constructing a heterojunction of T phase and H phase. This method bypasses the traditional thermal activation or chemical activation pathways, combines mechanical energy with lattice reconstruction at the atomic scale, and provides a new solution for constructing novel heterojunctions.

[0052] Figure 4 Figure c in is an enlarged STM image of the area within the black dashed box in Figure b, which shows that the mechanical collision causes a partial transformation of the T-NbSe2 island with an obvious charge density wave (CDW) pattern into the H phase with an unobvious CDW pattern, and forms an interface between the T-phase and H-phase islands. Figure d is the dI / dV spectrum measured at the position marked by the black dot in Figure c, which confirms the transition from the T phase to the H phase. The spectrum shows that the upper Hubbard band (UHB) disappears and metallicity appears, which is consistent with the electronic characteristics of H-NbSe2 in previous studies.

[0053] Furthermore, in some embodiments of the present application, the tunneling current of the STM is set to 1 nA, and the bias voltage is set to -0.1 V.

[0054] Specifically, setting the tunneling current to 1 nA has obvious advantages. On the one hand, this current value is relatively small, which can effectively reduce the damage to the surface of the two-dimensional TMD material and prevent local structural damage or irreversible changes in the electronic state of the material caused by excessive current, ensuring the integrity of the material during the manipulation process. On the other hand, this current can provide sufficient signal strength, enabling the STM probe to accurately sense the surface topography and electronic structure information of the material, providing strong support for the subsequent positioning and manipulation of the T-phase nanodots.

[0055] The bias voltage is set to -0.1 V to cooperate with the tunneling current. It can optimize the interaction between the STM probe and the two-dimensional TMD material. By adjusting the barrier height between the probe and the material, it affects the electron tunneling probability and thus controls the interaction force. This interaction force is the driving force for the movement and phase transition manipulation of the T-phase nanodots. Precisely setting the bias voltage can achieve fine control of the movement trajectory and phase transition process of the nanodots.

[0056] The coordinated setting of the tunneling current and the bias voltage creates stable experimental conditions for the phase transition manipulation of the two-dimensional TMD material, which helps to improve the accuracy and reliability of the manipulation, laying a foundation for in-depth exploration of the phase transition mechanism of two-dimensional materials and the development of new nanodevices.

[0057] Furthermore, in some embodiments of the present application, the preset moving speed of the STM probe is 1 nm / s.

[0058] Specifically, from the perspective of force control, this speed can achieve a uniform and stable distribution of the interaction force between the probe and the material. Slow movement can accurately control the magnitude and direction of the interaction force, preventing sudden changes in the interaction force caused by too fast a speed and interfering with the movement and phase transition of the nanodots.

[0059] In terms of the influence on the movement of the nanodots, a speed of 1 nm / s enables the T-phase nanodots to move in a controllable manner. The nanodots can rotate and translate around the vertex in a controlled manner. By adjusting this speed, the rotation angle, speed, and translation distance can be finely controlled, reducing the randomness and uncertainty of the movement and improving the repeatability and stability of the phase transition manipulation.

[0060] Regarding the experimental results, setting an appropriate moving speed is conducive to obtaining high-quality data and results. At this speed, the movement and phase transition phenomena of the nanodots can be observed more clearly, providing strong support for in-depth research on the phase transition mechanism of two-dimensional TMD materials. At the same time, it also helps to optimize the phase transition manipulation process and improve the performance and reliability of nanodevices.

[0061] Furthermore, in some embodiments of the present application, the operating environment temperature of the STM probe is liquid helium temperature.

[0062] Specifically, in the method for manipulating the phase transition of two-dimensional TMD materials provided by some embodiments of the present application, the operating temperature of the STM probe is set to the liquid helium temperature (about 4.2 K). The liquid helium temperature can suppress thermal noise, improve the signal-to-noise ratio, and make the experimental data more accurate and reliable. The low-temperature environment helps to stabilize the electronic state of the material and is conducive to accurately capturing the changes in the electronic structure during the phase transition. The liquid helium temperature provides a more stable and pure experimental environment for the operation of the STM probe, ensuring the smooth progress of the phase transition manipulation.

[0063] In summary, setting the operating temperature of the STM probe to the liquid helium temperature has great advantages in reducing noise, stabilizing the electronic state of the material, and reducing external interference, which is beneficial to improving the accuracy, stability, and reliability of the two-dimensional TMD material phase transition manipulation experiment, and lays a foundation for in-depth research on the material phase transition mechanism and the development of new nano-devices.

[0064] Further, in some embodiments of the present application, the rotation angle of the T-phase nanoisland of the two-dimensional TMD material is calculated by measuring the angular displacement of the island edge before and after the rotation of the T-phase nanoisland.

[0065] Specifically, through high-precision imaging techniques, such as scanning tunneling microscopy (STM), the surface topography images of the nanoisland before and after rotation are obtained. The island edge in the image is finely processed and analyzed to extract the geometric feature information of the edge. By comparing the geometric features of the island edge before and after rotation, the displacement of the edge angle is calculated. Specifically, the positions of the corresponding points on the island edge before and after rotation are determined, and through geometric calculation methods, such as vector analysis or angle difference calculation, the displacement of the edge angle is obtained. Based on the geometric relationship between the island edge angle displacement and the overall rotation angle of the nanoisland, the rotation angle of the T-phase nanoisland of the two-dimensional TMD material is deduced. Since the rotation of the nanoisland is a rigid body motion, there is a definite mathematical relationship between the edge angle displacement and the overall rotation angle, and through this relationship, the rotation angle of the T-phase nanoisland of the two-dimensional TMD material can be accurately calculated.

[0066] In addition, the embodiments of the present application also provide a two-dimensional TMD material, which is made by the method described in any one of the above. The specific preparation method of this two-dimensional TMD material refers to the above embodiments. Since the specific preparation method of the two-dimensional TMD material adopts all the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated here one by one.

[0067] As described above, the above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for manipulating the phase transition of two-dimensional TMD materials, characterized in that, Comprising the following steps: By adjusting the tunneling current and / or bias voltage of the STM, the STM probe is brought close to the two-dimensional TMD material; Moving the STM probe along a specific trajectory at a preset moving speed, so that the T-phase nanoislands of the two-dimensional TMD material move; And Making the T-phase nanoislands of the two-dimensional TMD material mechanically collide with adjacent H-phase nanoislands, so that the T-phase nanoislands undergo a phase change to produce a heterojunction structure of T-phase and H-phase nanoislands.

2. The method according to claim 1, wherein After bringing the STM probe close to the two-dimensional TMD material by adjusting the tunneling current and / or bias voltage of the STM, it further includes: Positioning the STM probe at a position adjacent to the vertex of the T-phase nanoisland of the two-dimensional TMD material.

3. The method according to claim 2, wherein The moving the STM probe along a specific trajectory at a preset moving speed, so that the T-phase nanoislands of the two-dimensional TMD material move, includes: Moving the STM probe along a specific trajectory at a preset moving speed, so that the T-phase nanoislands of the two-dimensional TMD material rotate controllably around the vertex while performing translational motion.

4. The method according to any one of claims 1 to 3, characterized in that, The T-phase nanoislands are T-NbSe2 islands, and the H-phase nanoislands are H-NbSe2 islands.

5. The method according to claim 4, characterized in that Before bringing the STM probe close to the two-dimensional TMD material by adjusting the tunneling current and / or bias voltage of the STM and positioning it at a position adjacent to the vertex of the T-phase nanoisland of the two-dimensional TMD material, it further includes: Preparing a two-dimensional TMD material in which H-NbSe2 islands and T-NbSe2 islands coexist on bilayer graphene epitaxially grown on a SiC substrate.

6. The method according to claim 1, characterized in that, The tunneling current of the STM is set to 1 nA, and the bias voltage is set to -0.1 V.

7. The method according to claim 1, characterized in that, The preset moving speed of the STM probe is 1 nm / s.

8. The method according to claim 1, wherein The operating environment temperature of the STM probe is liquid helium temperature.

9. The method according to claim 3, wherein The rotation angle of the T-phase nanoislands of the two-dimensional TMD material is calculated by measuring the angular displacement of the island edge before and after the rotation of the T-phase nanoislands.

10. A two-dimensional TMD material, characterized in that, The two-dimensional TMD material is made by the method according to any one of claims 1 to 9.

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