CN114649200A - Method for transferring two-dimensional semiconductor material - Google Patents

Abstract

The invention provides a method for transferring a two-dimensional semiconductor material, comprising: preparing a two-dimensional semiconductor material on a growth substrate to obtain a two-dimensional semiconductor material/growth substrate structure; spin-coating PMMA and heating and curing to obtain a PMMA cured adhesive layer/two-dimensional semiconductor material Three-layer structure of two-dimensional semiconductor material/growth substrate; keep the transfer environment humidity greater than 50% RH, sandwich the two-layer structure of PMMA cured adhesive layer/two-dimensional semiconductor material in the target area and attach it to the target substrate to obtain PMMA curing Adhesive layer/two-dimensional semiconductor material/target substrate three-layer structure, after standing at room temperature, acetone immersion and acetone removal treatment, and drying with a nitrogen gun to obtain a two-dimensional semiconductor material/target substrate double-layer structure. The dry transfer of the two-dimensional semiconductor material in the high humidity environment proposed by the invention not only ensures the transfer efficiency of molybdenum disulfide, but also avoids the introduction of wrinkles and pollution, and effectively improves the electrical performance of the single-layer molybdenum disulfide semiconductor transistor after the transfer.

Description

Transfer methods for two-dimensional semiconductor materials

technical field

The present invention relates to the technical field of semiconductor materials, in particular to the transfer of two-dimensional semiconductor materials, in particular to an efficient and lossless transfer method of two-dimensional semiconductor materials.

Background technique

Two-dimensional materials refer to materials in which electrons can move freely (planar motion) on the nanoscale (1-100 nm) in only two dimensions. Since the world's first two-dimensional material, graphene, was first discovered, two-dimensional materials have attracted considerable attention and research due to their extraordinary physical, electronic, and optoelectronic properties, including sensitivity, transparency, and semiconducting properties. Up to now, two-dimensional materials have formed a huge family, including several categories such as graphene, transition metal chalcogenides, and black phosphorus. Currently, the most widely studied two-dimensional semiconductor materials are transition metal chalcogenides. Taking molybdenum disulfide as an example, the single-layer molybdenum disulfide has good electrical properties, the electron mobility at room temperature is as high as 200cm ² v ^-1 s ^-1 , and the electronic switching ratio is as high as 10 ⁸ , which has a huge application in high-performance logic circuits. Potential, hopefully, to shine in the post-Moore era.

In the prior art, a two-dimensional semiconductor material is usually prepared on a growth substrate by chemical vapor deposition, and then transferred from the growth substrate to a target substrate to prepare a semiconductor transistor.

Since the electrical properties of 2D semiconductor materials are easily affected by the material morphology, how to quickly and non-destructively transfer 2D semiconductor materials from the growth substrate to the target substrate has become a key issue in the preparation of 2D semiconductor materials. .

At present, the existing two-dimensional material transfer methods mainly include PMMA water-assisted transfer method and PDMS dry transfer method. In the PMMA water-assisted transfer method, the molybdenum disulfide material needs to be in direct contact with pure water. After the molybdenum disulfide is transferred to the target substrate and air-dried, the two-dimensional material is prone to wrinkles, and impurities in the pure water are also prone to contamination of the material. In the PDMS dry transfer method, PDMS is directly attached to the growth substrate, and the two-dimensional material is transferred out by heating to increase the adsorption force, and then attached to the target substrate. However, PDMS cannot be completely attached to the growth substrate. Closely attached, many materials cannot be transferred, or even damaged, and the transfer efficiency is low.

Therefore, existing 2D material transfer methods will damage, wrinkle, or contaminate the original 2D semiconductor thin film during the transfer process, affecting the electrical properties of the transferred material.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose an efficient and non-destructive transfer method for two-dimensional semiconductor materials, which uses PMMA instead of PDMS, and dry transfer of single-layer two-dimensional materials in a high humidity environment not only ensures the transfer efficiency of two-dimensional materials, but also avoids the introduction of wrinkles and pollution caused by traditional water-assisted transfer methods, which effectively improves the transfer efficiency. Electrical properties of single-layer two-dimensional material semiconductor thin films.

In order to achieve the above object, a first aspect of the present invention proposes a method for transferring a two-dimensional semiconductor material, comprising:

Step 1, using chemical vapor deposition method to prepare a two-dimensional semiconductor material on a growth substrate to obtain a two-dimensional semiconductor material/growth substrate structure;

Step 2. Spin-coat PMMA on the surface of the two-dimensional semiconductor material/growth substrate, and place the spin-coated growth substrate on a hot plate for heating and curing, and the cured PMMA condenses into a thin film on the surface of the growth substrate, That is, the PMMA cured adhesive layer, thereby obtaining the three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/growth substrate;

Step 3. Keep the transfer environment humidity above 50% RH, observe the three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/growth substrate under a microscope, determine the target area that needs to be transferred, and use a small knife to define the area The PMMA cured adhesive layer is separated from other areas, and then the two-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material in the target area is clamped from the growth substrate and directly attached to the target substrate with tweezers to obtain PMMA curing. Adhesive layer/two-dimensional semiconductor material/target substrate three-layer structure;

Step 4. Leave the three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate at room temperature for a certain period of time, and then place the three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate at room temperature. Soak in acetone solution to remove the PMMA cured adhesive layer on the surface, and finally put the soaked PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate three-layer structure in isopropyl alcohol for 5 minutes to remove the residual acetone solution; Finally, it is dried with a nitrogen gun to obtain a double-layer structure of the two-dimensional semiconductor material/target substrate, and the transfer of the two-dimensional semiconductor material is completed.

As an optional embodiment, in the step 2, PMMA is spin-coated on the surface of the two-dimensional semiconductor material/growth substrate, wherein the PMMA specification is 200k, the rotation speed is set to 1000-1200r/min, and the rotation time is 1-5min.

As an optional embodiment, in the step 2, the spin-coated PMMA growth substrate is placed on a hot plate for heating and curing, wherein the heating temperature is 80±10° C. and the heating time is 3-5 min.

As an optional embodiment, in the step 2, the thickness of the PMMA cured adhesive layer is 500-900 nm.

As an optional embodiment, the two-dimensional semiconductor material includes one of MoS ₂ , WS ₂ , and MoSe ₂ , and the growth substrate includes SiO ₂ /Si, HfO ₂ /Si, and soda lime glass. A sort of.

As an optional embodiment, in the step 3, the transfer environment is a clean room of class 100, and the dust particles of 0.5 μm per cubic meter in the air are less than 1 million.

As an optional embodiment, in the step 3, the tweezers used in the transfer process are sharp-nosed anti-static tweezers.

As an optional embodiment, in the step 4, the standing time at room temperature is 8-16 h.

As an optional embodiment, in the step 4, the soaking time in normal temperature acetone solution is 1-5h; the soaking time in isopropanol is 1-30min.

By the embodiments according to the present invention above, the significant advantages compared to the existing ones are:

The transfer method of the two-dimensional semiconductor material of the present invention uses PDMS instead of PMMA, and performs dry transfer of the two-dimensional semiconductor material in a high humidity environment, so as to solve the shortcomings of the wet transfer and dry transfer in the prior art. The transfer efficiency of the two-dimensional material is guaranteed, and the introduction of wrinkles and pollution caused by the traditional water-assisted transfer method is avoided, realizing the efficient and non-destructive transfer of the two-dimensional semiconductor material, and effectively improving the electrical properties of the single-layer two-dimensional material semiconductor film after transfer. , so as to solve the problem that the existing transfer method will damage, wrinkle or contaminate the original two-dimensional semiconductor film during the transfer process and affect the electrical properties of the transfer material.

It is to be understood that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, are considered to be part of the inventive subject matter of the present disclosure to the extent that such concepts are not contradictory. Additionally, all combinations of the claimed subject matter are considered to be part of the inventive subject matter of this disclosure.

The foregoing and other aspects, embodiments and features of the present teachings can be more fully understood from the following description when taken in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and/or benefits of the exemplary embodiments, will be apparent from the description below, or learned by practice of specific embodiments in accordance with the teachings of this invention.

Description of drawings

The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by the same reference numeral. For clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein:

1a-1h are schematic diagrams of a transfer method of a two-dimensional semiconductor material according to an exemplary embodiment of the present invention, that is, a process of dry transfer of a two-dimensional semiconductor material using PMMA in a high humidity environment;

Figure 2a is an optical microscope image of molybdenum disulfide obtained after transferring it to a target substrate using the transfer method shown in Figures 1a-1h, and Figure 2b is a transfer using Example 2. The optical microscope image of molybdenum disulfide obtained after transferring molybdenum disulfide to the target substrate;

Fig. 3a is an AFM characterization of the transferred molybdenum disulfide exemplified in Fig. 2a, and Fig. 3b is an AFM characterization of the molybdenum disulfide obtained after transferring the molybdenum disulfide to a target substrate using the transfer method of Example 3;

4 is a schematic structural diagram of a molybdenum disulfide transistor based on molybdenum disulfide;

5 is a schematic diagram comparing the transfer characteristic curves of the molybdenum disulfide transistor prepared by the molybdenum disulfide obtained by the transfer method of the example of the present invention and the molybdenum disulfide transistor prepared by the molybdenum disulfide obtained by the transfer method of Example 3;

6a-6b are schematic diagrams of output characteristic curves of a molybdenum disulfide transistor prepared based on molybdenum disulfide obtained by the transfer method exemplified in the present invention and a molybdenum disulfide transistor prepared by the transfer method of Example 3, respectively.

The meanings of each mark in the accompanying drawings are as follows:

10. Growth substrate; 20. Two-dimensional semiconductor material; 30. PMMA cured adhesive layer; 50. Target substrate.

100, PMMA; 200, heating plate; 300, constant humidity box (ambient humidity controlled at 50% RH); 400, small carving knife; 500; tweezers (preferably anti-static tweezers); 600, acetone solution; 700, IPA solution; 800. Nitrogen gun.

Detailed ways

In order to better understand the technical content of the present invention, specific embodiments are given and described below in conjunction with the accompanying drawings.

Aspects of the invention are described in this disclosure with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described in greater detail below, can be implemented in any of a variety of ways, as the concepts and embodiments disclosed herein do not limited to any implementation. Additionally, some aspects of the present disclosure may be used alone or in any suitable combination with other aspects of the present disclosure.

Combined with the transfer method of 2D semiconductor materials shown in Figures 1a-1h, the aim is to propose a dry transfer method of 2D semiconductor materials using PMMA in a high humidity environment, which not only ensures the transfer efficiency of molybdenum disulfide, It also avoids the introduction of wrinkles and pollution, makes up for the shortcomings of the two transfer methods (dry method and wet method) in the prior art, and effectively improves the electrical performance of the single-layer molybdenum disulfide semiconductor transistor after the transfer.

As an example, the dry transfer method of two-dimensional semiconductor material using PMMA in a high humidity environment, the process includes:

Step 1, using chemical vapor deposition method to prepare a two-dimensional semiconductor material on a growth substrate to obtain a two-dimensional semiconductor material/growth substrate structure;

Step 2. Spin-coat PMMA on the surface of the two-dimensional semiconductor material/growth substrate, and place the spin-coated growth substrate on a hot plate for heating and curing, and the cured PMMA condenses into a thin film on the surface of the growth substrate, That is, the PMMA cured adhesive layer, thereby obtaining the three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/growth substrate;

Step 3. Keep the transfer environment humidity above 50% RH, observe the three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/growth substrate under a microscope, determine the target area that needs to be transferred, and use a small knife to define the area The PMMA cured adhesive layer is separated from other areas, and then the two-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material in the target area is clamped from the growth substrate and directly attached to the target substrate with tweezers to obtain PMMA curing. Adhesive layer/two-dimensional semiconductor material/target substrate three-layer structure;

Step 4. The three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate is allowed to stand for a certain period of time at room temperature, and the goal is to make the two-dimensional semiconductor material and the target substrate adsorb more closely; then the PMMA is cured The three-layer structure of adhesive layer/two-dimensional semiconductor material/target substrate is placed in acetone solution at room temperature to remove the PMMA cured adhesive layer on the surface, and finally the soaked PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate three The layer structure was soaked in isopropanol for 5 minutes to remove the residual acetone solution; finally, it was blown dry with a nitrogen gun to obtain a two-layer structure of the two-dimensional semiconductor material/target substrate, and the transfer of the two-dimensional semiconductor material was completed.

In step 3 of the foregoing embodiment, the reason for maintaining the high humidity of the transfer environment is that the high humidity will infiltrate the PMMA cured adhesive layer, making it more viscous, which is beneficial to lift the two-dimensional semiconductor material from the growth substrate. .

As an optional embodiment, in the step 2, PMMA is spin-coated on the surface of the two-dimensional semiconductor material/growth substrate, wherein the PMMA specification is 200k, the rotation speed is set to 1000-1200r/min, and the rotation time is 1-5min.

As an optional embodiment, in the step 2, the spin-coated PMMA growth substrate is placed on a hot plate for heating and curing, wherein the heating temperature is 80±10° C. and the heating time is 3-5 min.

As an optional embodiment, in the step 2, the thickness of the PMMA cured adhesive layer is 500-900 nm.

As an optional embodiment, the two-dimensional semiconductor material includes one of MoS ₂ , WS ₂ , and MoSe ₂ , and the growth substrate includes SiO ₂ /Si, HfO ₂ /Si, and soda lime glass. A sort of.

As an optional embodiment, in the step 3, the transfer environment is at least a class 100 ultra-clean room, and the dust particles of 0.5 μm per cubic meter in the air are less than 1 million.

As an optional embodiment, in the step 3, the tweezers used in the transfer process are sharp-nosed anti-static tweezers.

As an optional embodiment, in the step 4, the standing time at room temperature is 8-16 h.

As an optional embodiment, in the step 4, the soaking time in normal temperature acetone solution is 1-5h; the soaking time in isopropanol is 1-30min.

In the following, we take the two-dimensional molybdenum disulfide material as an example, and describe the implementation of the transfer method of the present invention in more detail in combination with specific examples.

Example 1

Step 1. Use chemical vapor deposition to deposit and prepare MoS ₂ two-dimensional semiconductor material on the HfO ₂ /Si growth substrate to obtain a two-dimensional semiconductor material/growth substrate two-layer structure, as shown in Figure 1a;

Step 2, spin-coating PMMA on the surface of the two-dimensional semiconductor material/growth substrate; wherein the PMMA specification is 200k, the rotation speed is set to 1000r/min, and the rotation time is 1min;

Then, the spin-coated PMMA growth substrate was placed on a hot plate for heating and curing, as shown in Figure 1b, the heating temperature was 80 °C, and the heating time was 5 min; the cured PMMA would condense on the surface of the growth substrate into a layer of about A film with a thickness of 700 nm is obtained to obtain a three-layer structure of PMMA cured adhesive layer/two-dimensional semiconductor material/growth substrate;

Step 3. Use a constant humidity box or an air humidifier to keep the humidity of the transfer environment above 50% RH, so that the PMMA cured adhesive layer has higher viscosity and can easily lift the two-dimensional semiconductor material from the growth substrate; under a microscope Observe the three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/growth substrate, find the target area that needs to be transferred, and use a small knife to separate the PMMA cured adhesive layer in this area from other areas, as shown in Figure 1c; then Use tweezers to sandwich the two-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material in the target area and directly attach it to the target substrate to obtain a three-layer structure of PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate, as shown in Figure 1d and shown in 1e;

Step 4. The three-layer structure of the PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate is allowed to stand at room temperature for about 12 hours. The goal is to make the two-dimensional semiconductor material and the target substrate adsorb more closely; Soak in acetone solution at room temperature for 4 hours to remove the PMMA cured adhesive layer on the surface, as shown in Figure 1f;

Finally, the structure was soaked in isopropanol for 5 minutes to remove the residual acetone solution, as shown in Figure 1g; then dried with a nitrogen gun to obtain a two-dimensional semiconductor material/target substrate double-layer structure, and the transfer was completed, as shown in the figure 1h shown.

Example 2

The operation is similar to that of Example 1, except that the transfer process in Step 3 is not carried out in a high humidity environment, but in a lower than 50% RH environment, and in Example 2, the humidity of the transfer environment is 30% .

As shown in Fig. 2b, the molybdenum disulfide two-dimensional material obtained based on the transfer method in Example 2 had breakage defects.

Example 3

The operation is similar to that of Example 1, except that the transfer process in Step 3 is not carried out in a humidity environment greater than 50% RH, but carried out in pure water.

As shown in Figure 3b, the molybdenum disulfide two-dimensional material obtained based on the transfer method in Example 3 has wrinkle defects.

Optical Microscopic Characterization

2a and 2b, it can be seen that based on the transfer method (Example 1) of the exemplary embodiment of FIGS. 1a-1f of the present invention, the molybdenum disulfide transferred to the target substrate is intact, as Example 2 of Comparative Example 1 Among them, using the transfer method of Example 2, the molybdenum disulfide transferred to the target substrate was damaged in many places. The difference between Example 1 and Comparative Example 1 is the environmental humidity during transfer, indicating that environmental humidity has a significant impact on material transfer. . In the present invention, a transfer environment with a high humidity of RH50% or more is adopted to realize the efficient and non-destructive transfer of the two-dimensional material, and the transfer effect is excellent.

The example of PMMA transfer molybdenum disulfide under low humidity is similar to the PDMS dry transfer process. The adhesive layer and the growth substrate are not adsorbed tightly enough, which leads to the damage of the transferred two-dimensional material. Therefore, the time delay of the control group is verified. The superiority of dry transfer of PMMA over traditional dry transfer under high humidity.

AFM characterization

3a and 3b, it can be seen that based on the transfer method (Example 1) of the exemplary embodiment of FIGS. 1a-1f of the present invention, the morphology of the molybdenum disulfide transferred to the target substrate is very flat, which is regarded as the In Example 3, using the transfer method of Example 3, many wrinkles appeared in the molybdenum disulfide transferred to the target substrate. Since the transfer process in Comparative Example 2 was carried out in pure water, which is consistent with the traditional wet transfer of PMMA, it means that the direct contact between molybdenum disulfide and water during the transfer process will cause the molybdenum disulfide to wrinkle and reduce the quality of the film. This is because the capillary force of water acts on molybdenum disulfide. Therefore, this control experiment further verifies the superiority of dry transfer of PMMA compared with traditional wet transfer under high humidity.

Comparison of Molybdenum Disulfide Transistor Characteristics

Taking the molybdenum disulfide transistor shown in FIG. 4 as an example, FIG. 5 exemplarily shows the molybdenum disulfide transistor prepared based on the molybdenum disulfide obtained by the transfer method (Example 1) of the present invention and the transfer based on Example 3. Comparison of transfer characteristic curves of molybdenum disulfide transistors prepared with molybdenum disulfide obtained by the method.

One of the main parameters for evaluating transistor performance is the field-effect mobility g _m , which is calculated as follows:

Among them, L and W are the channel length and channel width of the transistor respectively, and Cox is the unit capacitance of the back gate dielectric HfO ₂ .

Combining with the comparison of the transfer characteristic curves of the molybdenum disulfide transistor shown in FIG. 5 , and substituting the data corresponding to the two examples in the figure into the mobility formula, it can be concluded that the field-effect mobilities of Example 1 and Example 3 are 35 cm ² v respectively. ^-1 s ^-1 and 18cm ² v ^{- 1} s ^-1 , it can be seen that the former is nearly twice that of the latter, indicating that compared with the traditional wet transfer, the dry transfer of PMMA under high humidity proposed by the present invention can be largely Protect the quality of 2D materials and improve their electrical properties.

Figures 6a-6b exemplarily show molybdenum disulfide transistors prepared based on molybdenum disulfide obtained by the transfer method of the present invention (Example 1) and molybdenum disulfide prepared based on molybdenum disulfide obtained by the transfer method of Example 3 The output characteristic curve of the transistor.

It can be seen from the figure that under the same voltage, the saturation currents of the molybdenum disulfide transistors in Example 1 and Example 3 are 100A/m and 20A/m, respectively, and the former is nearly 5 times that of the latter, indicating that the former has far superior electrical performance. It is far superior to the latter, which further proves the advantages of dry transfer of PMMA under high humidity for the application of two-dimensional semiconductor materials in logic devices.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined according to the claims.

Claims (9)

1. A method of transferring two-dimensional semiconductor material, comprising the steps of:

step 1, depositing a two-dimensional semiconductor material on a growth substrate to obtain a two-dimensional semiconductor material/growth substrate structure;

step 2, spin-coating PMMA on the surface of the two-dimensional semiconductor material/growth substrate, placing the growth substrate coated with PMMA on a hot plate for heating and curing, and condensing the cured PMMA on the surface of the growth substrate to form a thin film, namely a PMMA cured glue layer, thereby obtaining a three-layer structure of PMMA cured glue layer/two-dimensional semiconductor material/growth substrate;

step 3, keeping the humidity of a transfer environment to be more than 50% RH, observing the three-layer structure of the PMMA cured glue layer/two-dimensional semiconductor material/growth substrate under a microscope, determining a target area needing to be transferred, dividing the PMMA cured glue layer of the area from other areas, clamping the two-layer structure of the PMMA cured glue layer/two-dimensional semiconductor material of the target area from the growth substrate by using tweezers, and directly attaching the two-layer structure of the PMMA cured glue layer/two-dimensional semiconductor material/target substrate to the target substrate to obtain the three-layer structure of the PMMA cured glue layer/two-dimensional semiconductor material/target substrate;

step 4, standing the PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate three-layer structure for a certain time at room temperature, then soaking the PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate three-layer structure in a normal-temperature acetone solution to remove the PMMA cured adhesive layer on the surface, finally soaking the soaked PMMA cured adhesive layer/two-dimensional semiconductor material/target substrate three-layer structure in isopropanol for 5min, and removing the residual acetone solution; and finally, drying by using a nitrogen gun to obtain a two-dimensional semiconductor material/target substrate double-layer structure, and completing the transfer of the two-dimensional semiconductor material.

2. The method as claimed in claim 1, wherein in step 2, PMMA is spin-coated on the surface of the two-dimensional semiconductor material/growth substrate, wherein the PMMA specification is 200k, the rotation speed is set to 1000-.

3. The method for transferring two-dimensional semiconductor material according to claim 1, wherein the growth substrate coated with PMMA is placed on a hot plate for heating and curing, wherein the heating temperature is 80 +/-10 ℃, and the heating time is 3-5 min.

4. The method as claimed in claim 1, wherein the thickness of the PMMA cured adhesive layer is 500-900 nm.

5. The method according to claim 1, wherein the two-dimensional semiconductor material comprises MoS₂、WS₂、MoSe₂Wherein the growth substrate comprises SiO₂/Si、HfO₂One of/Si and soda-lime glass.

6. The method of claim 1, wherein in step 3, the transfer environment is a clean room hundred-class area, and the number of dust particles in air is less than 100 ten thousand with a particle size of 0.5 μm per cubic meter.

7. The method for transferring a two-dimensional semiconductor material according to claim 1, wherein in the step 3, the tweezers used in the transfer process are tip antistatic tweezers.

8. The method for transferring two-dimensional semiconductor material according to claim 1, wherein the standing time at room temperature in step 4 is 8-16 h.

9. The method for transferring two-dimensional semiconductor material according to claim 1, wherein in the step 4, the soaking time in the normal temperature acetone solution is 1-5 h; soaking in isopropanol for 1-30 min.

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