A preparation device and method for twisted heterojunction based on second harmonic in-situ monitoring

Abstract

This invention discloses a fabrication apparatus and method for twisted heterojunctions based on in-situ monitoring of second harmonics. It enables fully optical, non-destructive, in-situ monitoring of the lattice orientation of two-dimensional material crystals, and allows for angle calibration of both the target sample and the sample to be transferred. This invention enables the fabrication of twisted heterojunctions at arbitrary angles, thereby greatly expanding the design and manufacturing capabilities of twisted devices, exploring more novel physical properties, and achieving large-scale device production.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of novel electronic devices, and particularly relates to a method for realizing all-optical, non-destructive, in-situ monitoring of the lattice orientation of a two-dimensional material crystal by utilizing the second harmonic model of a two-dimensional material, and can respectively perform angle calibration on a target sample and a sample to be transferred. Background Art

[0002] Twisted two-dimensional heterojunction refers to stacking two-dimensional materials or low-dimensional materials vertically together, and the lattice orientation between layers has a certain angle, such as double-layer twisted graphene, MX2 / MoS2, etc. This twisted two-dimensional heterojunction will have a great influence on the band structure and correlation strength of the original intrinsic material through the interlayer van der Waals interaction and lattice interaction, showing a variety of novel material properties such as superconductivity, Mott insulation, macroscopic magnetism, quantum Hall effect, etc., and these properties can be modulated by the twist angle, thus having a wide range of research space and application prospects. However, the preparation of this twisted two-dimensional heterojunction is still relatively difficult and has low precision. The lattice orientation angle can only be judged by the macroscopic optical appearance of the material, and it is difficult to identify the actual crystal axis position of the material, and there are great restrictions on the size of the material [Reference 1]. Common methods for determining the crystal axis include transmission electron microscopy and second harmonic optical methods. The wavelength of the electron beam in transmission electron microscopy is much shorter than that of visible light and ultraviolet light, and the energy is very high. It can easily obtain information such as the lattice arrangement, thickness and density of the sample, thereby analyzing the entire sample crystal information. However, this method is extremely destructive to the sample, and the sample preparation is troublesome, the equipment is expensive, and it requires specialized operators to operate. It is not compatible with the preparation process of twisted two-dimensional heterojunctions. For non-centrosymmetric materials, when the incident light is irradiated on the material, under the action of the second-order nonlinear polarization effect, an optical signal output with a frequency twice the frequency of the incident light is generated, which is the so-called two-dimensional harmonic nonlinear optical effect. For two-dimensional material systems, the second harmonic effect is directly related to the symmetry of the crystal structure of the material, and its intensity is very sensitive to the lattice symmetry of the material. By detecting the distribution diagram of the second harmonic intensity changing with the angle, the corresponding crystal structure can be analyzed. It has the characteristics of non-destructive, simple and fast, and a wide range of applications. It can realize non-contact measurement of materials in various complex environments and analyze local strain conditions. However, this method is currently usually used in the sample testing and analysis stage, and is not organically integrated with the sample preparation process. In addition, the design of the test sample stage is relatively simple and cannot meet the requirements of multi-axis precision movement [Reference 2].

[0003] Among them, document 1: Research progress on physical properties, preparation methods and applications of twisted bilayer graphene, ActaPhysicaSinica, 67, 246802 (2018);

[0004] Reference 2: Research on second harmonic generation and two-photon absorption characteristics of one-dimensional / two-dimensional semiconductor nanostructures, Liu Weiwei, Ph.D. thesis, Huazhong University of Science and Technology, 2017. Summary of the invention

[0005] Purpose of the invention: In view of the above-mentioned shortcomings, the present invention proposes a device and method for preparing a twisted heterojunction based on second harmonic in-situ monitoring, which can realize all-optical, non-destructive, in-situ monitoring of the lattice orientation of two-dimensional material crystals, and can perform angle calibration on the target sample and the sample to be transferred respectively, and can realize the preparation of twisted two-dimensional heterojunctions at any angle, thereby greatly expanding the design and manufacturing capabilities of twisted devices, exploring more novel physical properties and realizing large-scale production of devices.

[0006] Technical solution:

[0007] A preparation device for a twisted heterojunction based on second harmonic in-situ monitoring, comprising:

[0008] A target sample stage (1) is used to place a substrate of the target sample and rotate the target sample according to the twisting angle;

[0009] A transfer sample stage (2) is used to transfer the transfer sample to above the target sample on the target sample stage (1) and to attach the transfer sample to the target sample;

[0010] The second harmonic signal excitation optical path is used for incident laser signals with different polarization directions to be incident on the target sample or the transfer sample to excite the corresponding second harmonic signal;

[0011] A second harmonic signal collection optical path is used to collect the second harmonic signal excited by the incident laser signal and transmit it to the second harmonic signal detector;

[0012] The second harmonic signal detector (8) is used to detect the second harmonic signal collected by the second harmonic signal collection optical path to obtain the second harmonic signal intensity of the incident laser signal in the corresponding polarization direction.

[0013] A heating device is provided in the target sample stage, a substrate on which a hand-torn or CVD two-dimensional material target sample is pressed is provided on the target sample stage (1), a transfer sample fixture (23) is provided on the transfer sample stage (2), a heat release adhesive is affixed to the lower bottom surface of the transfer sample fixture (23), a two-dimensional material sample prepared by hand-torn or CVD method is pressed on the heat release adhesive, and a side of the heat release adhesive without the sample is affixed to the lower bottom surface of the transfer sample fixture.

[0014] The second harmonic signal excitation optical path is a reflective optical path, comprising a focusing objective lens (3), a second beam splitter (4), a filter set (5), a first beam splitter (6), a signal converging objective lens (7) and a bright field imaging CCD (9);

[0015] The focusing objective lens (3) is arranged above the target sample stage (1); the second beam splitter (4) is arranged above the focusing objective lens (3); the installation angle of the second beam splitter (4) is 45°; the filter group (5) is arranged above the second beam splitter (4); the first beam splitter (6) is arranged above the filter group (5); the installation angle of the first beam splitter (6) is 45°; the signal converging objective lens (7) is arranged above the first beam splitter (6); the second harmonic signal detector (8) is arranged above the signal converging objective lens (7); the focal plane of the signal converging objective lens (7) falls on the entrance port of the second harmonic signal detector (8); and a bright field imaging CCD (9) is arranged at the exit of the first beam splitter (6).

[0016] The second harmonic signal excitation optical path is a projection optical path, comprising an excitation signal focusing objective lens (31), a third beam splitter (10), a bright field imaging CCD (9), a signal collection and focusing objective lens (32), a filter group (5), and a signal converging lens (7);

[0017] A target sample holder (13) is provided on the target sample stage (1), and a substrate on which a hand-torn or CVD two-dimensional material sample is pressed is provided on the target sample holder (13);

[0018] The excitation signal focusing objective lens (31) is arranged directly below the substrate on the target sample fixture (13); a third beam splitter (10) with an installation angle of 45° is provided on the excitation signal focusing objective lens (31); and the bright field imaging CCD (9) is arranged at the exit of the third beam splitter (10); the signal collection focusing objective lens (32) is arranged directly above the substrate on the target sample fixture (13); the filter group (5) is arranged above the signal collection focusing objective lens (32); the signal convergence objective lens (7) is arranged above the filter group (5); and the second harmonic signal detector (8) is arranged above the signal convergence objective lens (7).

[0019] The target sample stage (1) is mounted on a target sample rotating stage (12), and the target sample rotating stage (12) is mounted on a target sample electric stage (11); the transfer sample stage comprises a transfer sample electric stage (21) and a transfer sample rotating stage (22) mounted on the transfer sample electric stage (21).

[0020] The substrate placed on the target sample stage (1) is a SiO2 / Si substrate, a mica substrate, a copper mesh substrate or a sapphire substrate.

[0021] The thermal release adhesive is PDMS, PC or PPC.

[0022] A method for preparing a twisted heterojunction with second harmonic in-situ monitoring comprises the steps of:

[0023] (1) Press the hand-torn or CVD two-dimensional material sample onto the substrate and place the substrate on the target sample stage;

[0024] (2) Introducing incident laser signals with different polarization directions through the second harmonic signal excitation optical path and focusing them on the surface of the target sample;

[0025] (3) The second harmonic signal excited by the target sample enters the second harmonic signal detector through the second harmonic signal collection optical path, and the second harmonic signal intensity of the incident laser signal in the corresponding polarization direction is recorded; based on this, a graph showing the relationship between the second harmonic intensity and the polarization angle of the incident laser signal is drawn, and the crystal axis curve of the target sample at this time is analyzed, and the characteristic signal intensity peak corresponding to the target sample rotation stage position 𝜃1, 𝜃2…𝜃n-1, 𝜃n is recorded accordingly; n refers to the number of the characteristic peak;

[0026] (4) After the two-dimensional material transfer sample is prepared by hand tearing or CVD method, the transfer sample is pressed onto the thermal release adhesive, and the side of the thermal release adhesive without the sample is attached to the bottom surface of the transfer sample fixture;

[0027] (5) Introducing incident laser signals with different polarization directions through the second harmonic signal excitation optical path and focusing them on the surface of the transferred sample;

[0028] (6) The second harmonic signal excited by the transfer sample enters the second harmonic signal detector through the second harmonic signal collection optical path, and the second harmonic signal intensity of the incident laser signal in the corresponding polarization direction is recorded; based on this, a graph showing the relationship between the second harmonic intensity and the polarization angle of the incident laser signal is drawn, and the crystal axis curve of the transfer sample at this time is analyzed, and the characteristic signal intensity peak corresponding to the transfer sample rotation stage position 𝜑1, 𝜑2…𝜑m-1, 𝜑m is recorded; m refers to the number of the characteristic peak;

[0029] (7) According to the design requirements of the target twist dislocation angle, after comparing the relationship between 𝜃n and 𝜑m, calculate the angle that the target sample stage needs to rotate;

[0030] (8) Rotate the target sample stage according to the angle obtained in step (7), adjust the transfer sample stage, and fit the transfer sample onto the target sample.

[0031] The incident laser signal introduced uses a picosecond laser with a wavelength of 532 nm, 800 nm, 1064 nm or 1550 nm or a femtosecond laser with a wavelength of 800 nm.

[0032] The transfer sample and the target sample are set to prepare heterojunctions of nanowires and two-dimensional materials or vertical stacking structures of three-dimensional crystals.

[0033] Beneficial effects: The present invention can realize the preparation of twisted heterojunctions at any angle, thereby greatly expanding the design and manufacturing capabilities of twisted devices, exploring more novel physical properties and realizing large-scale production of devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the second harmonic signal lattice orientation test of the target sample in the present invention.

[0035] Figure 2 Schematic diagram of the second harmonic signal lattice orientation test of the transferred sample in the present invention.

[0036] Figure 3 It is a schematic diagram of the structure of the projection light path adopted in the present invention.

[0037] Figure 4a This is a schematic diagram of the twisted two-dimensional heterojunction of the two-dimensional material target sample MoS2 and the transferred sample WSe2 in the present invention, wherein the designed crystal axis angle between the two materials is 30 degrees.

[0038] Figure 4b This is a graph showing the relationship between the second harmonic signal of the target sample MoS2 in the present invention and the angle.

[0039] Figure 4c This is the relationship between the second harmonic signal of the transferred sample and the angle.

[0040] Among them, 1 is the target sample stage, 11 is the target sample electric stage, 12 is the target sample rotating stage, 13 is the target sample fixture, 2 is the transfer sample stage, 21 is the transfer sample electric stage, 22 is the transfer sample rotating stage, 23 is the transfer sample fixture, 3 is the focusing objective lens, 31 is the excitation signal focusing objective lens, 32 is the signal collection focusing objective lens, 4 is the second beam splitter, 5 is the filter group, 6 is the first beam splitter, 7 is the signal convergence objective lens, 8 is the second harmonic signal detector, 9 is the bright field imaging CCD, and 10 is the third beam splitter. DETAILED DESCRIPTION

[0041] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0042] Figure 1 This is a schematic diagram of the second harmonic signal lattice orientation test of the target sample in the present invention. Figure 2 This is a schematic diagram of the second harmonic signal lattice orientation test of the transferred sample in the present invention. Figure 1 , 2 As shown, the preparation device of the twisted two-dimensional heterojunction based on second harmonic in-situ monitoring of the present invention includes a target sample stage 1, a transfer sample stage 2, a focusing objective lens 3, a second beam splitter 4, a filter set 5, a first beam splitter 6, a signal convergence objective lens 7, a second harmonic signal detector 8 and a bright field imaging CCD 9. The target sample stage 1 is mounted on a target sample rotating stage 12, and the target sample rotating stage 12 is mounted on a target sample electric stage 11; the transfer sample stage includes a transfer sample electric stage 21 and a transfer sample rotating stage 22 mounted on the transfer sample electric stage 21, and a transfer sample fixture 23 is provided on the transfer sample rotating stage 22. Both the target sample electric stage 11 and the transfer sample electric stage 21 include XYZ three-axis adjustment degrees of freedom.

[0043] The present invention adopts a reflective second harmonic signal excitation optical path, such as Figure 1 , 2 As shown, a focusing objective lens 3 is provided above the target sample stage 1, a second beam splitter 4 is provided above the focusing objective lens 3, the installation angle of the second beam splitter 4 is 45 degrees, a filter group 5 is provided above the second beam splitter 4, the filter group includes a long wave filter and a narrow band filter, a first beam splitter 6 is provided above the filter group 5, the installation angle of the first beam splitter 6 is 45 degrees, a signal converging objective lens 7 is provided above the first beam splitter 6, a second harmonic signal detector 8 is provided above the signal converging objective lens 7, the focal plane of the signal converging objective lens 7 falls on the entrance port of the second harmonic signal detector 8, and a bright field imaging CCD9 is provided at the outlet of the first beam splitter 6.

[0044] A SiO2 / Si substrate covered with a hand-torn or CVD two-dimensional material sample is placed on the target sample stage 1. The bright field imaging CCD is used to observe the sample morphology in the field of view, and a suitable target sample is selected and moved to the center of the field of view. The incident laser signals of different polarization directions are incident from the entrance of the second beam splitter 4, and are focused on the surface of the target sample or the transferred sample through the focusing objective lens 3. The wavelength of the second harmonic signal excited by the sample is collected by the focusing objective lens 3 and then filtered through the filter group 5 for filtering the interference signal. Then, the light signal is divided into a reflection and a transmission through the first beam splitter 6. The reflected light enters the bright field camera 9 to view the optical image of the sample, and the transmitted light is converged by the signal convergence lens 7 to enter the second harmonic signal detector 8. The second harmonic signal detector 8 detects the signal intensity in the corresponding polarization direction, and then obtains a relationship diagram between the second harmonic intensity and the polarization angle of the excitation light, so that the crystal axis curve of the target sample or the transferred sample at this time can be analyzed, and the characteristic signal intensity peak corresponding to the position of the target sample rotating stage is recorded accordingly.

[0045] A two-dimensional material sample prepared by hand tearing or CVD method is pressed on the PDMS thermal release adhesive, and then the side of the PDMS without the sample is attached to the lower bottom surface of the transfer sample fixture 23; the transfer sample fixture 23 is set on the transfer sample stage 2, the transfer sample rotating table 22 loads the transfer sample on the transfer sample fixture 23, and adjusts the position in the XYZ direction through the transfer sample electric stage 21 so that the transfer sample is located in the center of the field of view.

[0046] The target sample rotating table 12 adjusts the crystal axis orientation of the target sample according to actual needs, and the transfer sample electric table 21 adjusts the transfer sample to press down in the Z-axis direction and adjusts the position in the XY-axis direction, adjusts the position of the transfer sample and the target sample to overlap, and presses them to fit together.

[0047] A vacuum air pipe is provided inside the target sample stage, and a heating device is buried around its interior to give it vacuum adsorption and heating functions. The target sample stage heats the thermal release glue of PDMS, so that the transferred sample falls off from PDMS under the action of gravity and van der Waals force between heterojunction layers, forming a twisted two-dimensional heterojunction with a target angle.

[0048] The present invention can also adopt a projected second harmonic signal excitation optical path, such as Figure 3 As shown, a target sample holder 13 is provided on the target sample stage 1, a substrate with a hand-torn or CVD two-dimensional material sample pressed on the target sample holder 13 is provided, the transfer sample stage 2 and the target sample stage 1 are respectively arranged on both sides of the second harmonic signal excitation optical path, and the target sample stage 1 loads the target sample into the second harmonic signal excitation optical path through the target sample holder 13; the projected second harmonic signal excitation optical path includes an excitation signal focusing objective lens 31, a third beam splitter 10, a bright field imaging CCD9, a signal collection focusing objective lens 32, a filter group 5 and a signal converging lens 7;

[0049] The excitation signal focusing objective lens 31 is arranged directly below the substrate on the target sample fixture 13, and a third beam splitter 10 with an installation angle of 45° is provided on the excitation signal focusing objective lens 31, and a bright field imaging CCD9 is arranged at the exit of the first beam splitter 10; the signal collection focusing objective lens 32 is arranged directly above the substrate on the target sample fixture 13, and a filter group 5 is arranged above the signal collection focusing objective lens 32, a signal convergence objective lens 7 is arranged above the filter group 5, and a second harmonic signal detector 8 is arranged above the signal convergence objective lens 7.

[0050] The present invention also provides a method for preparing a twisted two-dimensional heterojunction based on second harmonic in-situ monitoring. The following embodiment is a method for preparing a heterojunction using a reflective second harmonic signal excitation optical path, comprising the following steps:

[0051] (1) Press the hand-torn or CVD two-dimensional material sample onto the SiO2 / Si substrate, and place the substrate on the target sample stage. Use the target sample electric stage to adjust the sample Z-axis height, and observe the sample morphology through the bright field imaging CCD. Select a suitable target sample and move it to the center of the field of view.

[0052] (2) An incident laser signal with a frequency of 𝜔 = 1064 nm is introduced at the entrance of the second beam splitter. After being reflected by the second beam splitter, it is focused on the surface of the target sample through the focusing objective lens.

[0053] (3) The second harmonic signal 2𝜔=532nm excited by the sample is collected by the focusing lens and enters the optical path. After the interference signal is filtered out by the filter group, it is converged by the signal convergence lens and enters the second harmonic signal detector. The signal intensity at this time is recorded.

[0054] (4) Change the polarization direction of the incident laser signal according to the actual test needs, for example, rotate the polarization direction every 10 degrees or every 30 degrees, and repeat the test process of (2) and (3), record the corresponding signal intensity, and then make a graph of the relationship between the second harmonic intensity and the polarization angle of the excitation light, such as Figure 4b As described above, the crystal axis curve of the target sample at this time can be analyzed, and the characteristic signal intensity peak corresponding to the target sample rotation stage position 𝜃1, 𝜃2...𝜃n-1, 𝜃n is recorded accordingly; n refers to the number of the characteristic peak;

[0055] (5) After the two-dimensional material sample is obtained by hand tearing or CVD method, the sample is pressed onto the PDMS thermal release adhesive, and the side of the PDMS without the sample is attached to the bottom surface of the transfer sample fixture; since the transfer sample fixture and PDMS are both transparent, the transfer sample can still be observed from above;

[0056] (6) Load the transfer sample through the transfer sample rotating stage, and adjust the XY direction position of the transfer sample stage and the Z axis position of the focusing objective lens so that the transfer sample is located in the center of the field of view and the sample morphology can be clearly observed through the bright field imaging CCD;

[0057] (7) An incident laser signal with a frequency of 𝜔 = 1064 nm is introduced at the entrance of the second beam splitter. After being reflected by the splitter, it is focused on the surface of the transfer sample through the focusing objective lens.

[0058] (8) The second harmonic signal 2𝜔=532nm wavelength excited by the transfer sample is collected by the focusing objective lens and enters the optical path. After the interference signal is filtered out by the filter group, it is converged by the signal convergence lens and enters the second harmonic signal detector PMT, and the signal intensity at this time is recorded;

[0059] (9) Change the polarization direction of the incident laser signal, for example, rotate the polarization direction every 10 degrees or every 30 degrees, and repeat the test process of (7) and (8), record the corresponding signal intensity, and then make a graph showing the relationship between the second harmonic intensity and the polarization angle of the excitation light, as shown in Figure 1. Figure 4c As shown, the crystal axis curve of the transferred sample at this time can be analyzed, and the characteristic signal intensity peak corresponding to the transfer sample rotation stage position 𝜑1, 𝜑2…𝜑m-1, 𝜑m is recorded; m refers to the number of the characteristic peak;

[0060] (10) According to the design requirements of the twist dislocation angle, such as Figure 4a As shown in Figure 2, the crystal axis angle of the heterojunction sample needs to be designed to be 30 degrees. Figure 4a According to the design needs, after comparing the relationship between 𝜃n and 𝜑m, the angle that the target sample rotation table needs to rotate is calculated. By rotating the target sample rotation table, the crystal axis orientation of the target sample is adjusted so that the crystal axis angle of the heterojunction sample reaches the designed 30 degree angle;

[0061] (11) Adjust the transfer sample electric stage so that the transfer sample is continuously pressed down in the Z-axis direction, and adjust the XY-axis position so that the transfer sample and the target sample overlap each other, and continue to press down until the two are bonded. After bonding, use the heating function of the target sample stage to weaken the viscosity of the PDMS thermal release adhesive, and the transfer sample falls off from the PDMS under the action of gravity and the van der Waals force between the heterojunction layers, thus forming a twisted two-dimensional heterojunction with a 30-degree angle.

[0062] The present invention can also adopt a heterojunction preparation method for a transmission type second harmonic signal excitation optical path structure, which is similar to the heterojunction preparation method for a reflection type second harmonic signal excitation optical path structure, and will not be described in detail here.

[0063] The embodiment of the present invention mainly introduces a method and device for preparing a twisted two-dimensional heterojunction with second harmonic in-situ monitoring, but is not limited thereto and can also be used for other band point tests;

[0064] 1) It can be used to prepare heterojunctions of nanowires and two-dimensional materials, such as the heterostructures of ZnO nanowires and graphene, the heterostructures of ZnO nanowires and MoS2, the heterostructures of ZnO nanosheets and graphene, and the heterostructures of ZrO2 nanowires and graphene;

[0065] 2) It can be used to prepare vertical stacking structures of three-dimensional crystals, such as the two-dimensional organic-inorganic hybrid perovskite CH3NH3PbX3 (X represents a halogen element) stacking structure;

[0066] The embodiment of the present invention uses a 1064nm picosecond laser as the second harmonic excitation signal, but is not limited thereto, and other similar lasers may also be used: a picosecond laser with a wavelength of 532nm, 800nm ​​or 1550nm, or a femtosecond laser with a wavelength of 800nm.

[0067] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations (such as quantity, shape, position, etc.) can be made to the technical scheme of the present invention, and these equivalent transformations are all protected by the present invention.

Claims

1. A device for preparing a twisted heterojunction based on second harmonic in-situ monitoring, characterized in that: include: A target sample stage (1), used for placing a substrate of a target sample and rotating the target sample according to a calculated rotation angle; The sample transfer stage (2) is used to transfer the transfer sample to above the target sample on the target sample stage (1), and to transfer the sample until it overlaps with the target sample, and to press the two until they are in contact with each other; The second harmonic signal excitation optical path is used for incident laser signals with different polarization directions to be incident on the target sample or the transfer sample to excite the corresponding second harmonic signal; A second harmonic signal collection optical path is used to collect the second harmonic signal excited by the incident laser signal and transmit it to the second harmonic signal detector; A second harmonic signal detector (8) is used to detect the second harmonic signal collected by the second harmonic signal collection optical path to obtain the second harmonic signal intensity of the incident laser signal in the corresponding polarization direction, and accordingly draw a relationship diagram of the second harmonic intensity versus the polarization angle of the incident laser signal, analyze the corresponding crystal axis curves of the target sample and the transferred sample, and record the corresponding position of the target sample rotation stage corresponding to the characteristic signal intensity peak, thereby calculating the required rotation angle of the target sample stage according to the twist angle, and rotating the target sample stage accordingly; Adjust the transfer sample stage to fit the transfer sample onto the target sample.

2. The preparation device according to claim 1, characterized in that: A heating device is provided in the target sample stage, a substrate on which a target sample of a two-dimensional material is pressed is provided on the target sample stage (1), a transfer sample fixture (23) is provided on the transfer sample stage (2), a heat release adhesive is affixed to the lower bottom surface of the transfer sample fixture (23), a two-dimensional material sample prepared by hand tearing or CVD method is pressed on the heat release adhesive, and a side of the heat release adhesive without a sample is affixed to the lower bottom surface of the transfer sample fixture.

3. The preparation device according to claim 1, characterized in that: The second harmonic signal excitation optical path is a reflective optical path, comprising a focusing objective lens (3), a second beam splitter (4), a filter set (5), a first beam splitter (6), a signal converging objective lens (7) and a bright field imaging CCD (9); The focusing objective lens (3) is arranged above the target sample stage (1); the second beam splitter (4) is arranged above the focusing objective lens (3); the installation angle of the second beam splitter (4) is 45°; the filter group (5) is arranged above the second beam splitter (4); the first beam splitter (6) is arranged above the filter group (5); the installation angle of the first beam splitter (6) is 45°; the signal converging objective lens (7) is arranged above the first beam splitter (6); the second harmonic signal detector (8) is arranged above the signal converging objective lens (7); the focal plane of the signal converging objective lens (7) falls on the entrance port of the second harmonic signal detector (8); and a bright field imaging CCD (9) is arranged at the exit of the first beam splitter (6).

4. The preparation device according to claim 3, characterized in that: The second harmonic signal excitation optical path is a projection optical path, comprising an excitation signal focusing objective lens (31), a third beam splitter (10), a bright field imaging CCD (9), a signal collection and focusing objective lens (32), a filter group (5), and a signal convergence objective lens (7); A target sample holder (13) is provided on the target sample stage (1), and a substrate on which a hand-torn or CVD two-dimensional material sample is pressed is provided on the target sample holder (13); The excitation signal focusing objective lens (31) is arranged directly below the substrate on the target sample fixture (13); a third beam splitter (10) with an installation angle of 45° is provided on the excitation signal focusing objective lens (31); the bright field imaging CCD (9) is arranged at the exit of the third beam splitter (10); the signal collection focusing objective lens (32) is arranged directly above the substrate on the target sample fixture (13); the filter group (5) is arranged above the signal collection focusing objective lens (32); the signal convergence objective lens (7) is arranged above the filter group (5); and the second harmonic signal detector (8) is arranged above the signal convergence objective lens (7).

5. The preparation device according to claim 1, characterized in that: The target sample stage (1) is mounted on a target sample rotating stage (12), and the target sample rotating stage (12) is mounted on a target sample electric stage (11); the transfer sample stage comprises a transfer sample electric stage (21) and a transfer sample rotating stage (22) mounted on the transfer sample electric stage (21).

6. The preparation device according to claim 1, characterized in that: The substrate placed on the target sample stage (1) is a SiO2 / Si substrate, a mica substrate, a copper mesh substrate or a sapphire substrate.

7. The preparation device according to claim 2, characterized in that: The thermal release adhesive is PDMS, PC or PPC.

8. A method for preparing a twisted heterojunction based on second harmonic in-situ monitoring using the preparation device of claim 1, characterized in that: Includes steps: (1) Pressing a two-dimensional material target sample onto a substrate, and placing the substrate on a target sample stage; (2) Introducing incident laser signals with different polarization directions through the second harmonic signal excitation optical path and focusing them on the surface of the target sample; (3) The second harmonic signal excited by the target sample enters the second harmonic signal detector through the second harmonic signal collection optical path, and the second harmonic signal intensity of the incident laser signal in the corresponding polarization direction is recorded; based on this, a graph showing the relationship between the second harmonic intensity and the polarization angle of the incident laser signal is drawn, and the crystal axis curve of the target sample at this time is analyzed, and the characteristic signal intensity peak corresponding to the target sample rotation stage position θ1, θ2...θn-1, θn is recorded; n refers to the number of the characteristic peak; (4) Press the two-dimensional material transfer sample onto the thermal release adhesive, and attach the side of the thermal release adhesive without the sample to the bottom surface of the transfer sample fixture; (5) introducing incident laser signals with different polarization directions through the second harmonic signal excitation optical path and focusing them on the transfer sample surface; (6) The second harmonic signal excited by the transfer sample enters the second harmonic signal detector through the second harmonic signal collection optical path, and the second harmonic signal intensity of the incident laser signal in the corresponding polarization direction is recorded; based on this, a graph showing the relationship between the second harmonic intensity and the polarization angle of the incident laser signal is drawn, and the crystal axis curve of the transfer sample at this time is analyzed, and the characteristic signal intensity peak corresponding to the transfer sample rotation stage position is recorded accordingly. m refers to the number of the characteristic peak; (7) According to the design requirements of the target twist dislocation angle, compare θn and After the relationship is established, the angle at which the target sample stage needs to rotate is calculated; (8) Rotate the target sample stage according to the angle obtained in step (7), adjust the transfer sample stage, and attach the transfer sample to the target sample.

9. The method for preparing a twisted two-dimensional heterojunction based on second harmonic in-situ monitoring according to claim 8, characterized in that: The incident laser signal introduced uses a picosecond laser with a wavelength of 532 nm, 800 nm, 1064 nm or 1550 nm or a femtosecond laser with a wavelength of 800 nm.

10. The method for preparing a twisted two-dimensional heterojunction based on second harmonic in-situ monitoring according to claim 8, characterized in that: The transfer sample and the target sample are set to prepare heterojunctions of nanowires and two-dimensional materials or vertical stacking structures of three-dimensional crystals.

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