Preparation method of high-mobility p-type two-dimensional WS2

Abstract

The invention relates to a preparation method of high-mobility p-type two-dimensional WS2, the high-mobility p-type two-dimensional WS2 and application of the high-mobility p-type two-dimensional WS2, WO3 and S are used as reaction precursors for preparing the WS2, ammonia water is used as a solvent for liquid phase assistance, secondary nucleation and longitudinal growth of the WS2 are inhibited, transverse growth of the WS2 is promoted, and therefore preparation of large-size and single-layer two-dimensional WS2 is facilitated. And a space confinement is used, so that a sufficient precursor source is provided for the growth process of the two-dimensional WS2. The reaction is carried out under an S-rich condition, so that a certain W vacancy exists in the two-dimensional WS2, an acceptor energy level is introduced, and the two-dimensional WS2 shows a p-type conductive characteristic. The p-type field effect transistor prepared from the two-dimensional WS2 prepared by the invention has high hole mobility and large on-off ratio.

Description

Technical Field

[0001] The present invention belongs to the technical field of two-dimensional material application, and relates to a method for preparing a high-mobility p-type two-dimensional WS2, as well as the high-mobility p-type two-dimensional WS2 and its application. Background Art

[0002] Two-dimensional materials refer to materials in which electrons can move freely only in two non-nanoscale dimensions. Their atomic arrangement, size, bond energy, etc. are similar in two dimensions and are significantly stronger than third-dimensional nanomaterials. In 2004, scholars from the University of Manchester used tape to mechanically peel off a single layer of graphene from a graphite block, verifying that two-dimensional materials can exist stably at room temperature. In recent years, two-dimensional transition metal dichalcogenides (TMDCs) have been widely regarded as star materials with great potential for future electronic device applications because of their graphene-like two-dimensional structure. Compared with traditional silicon transistors, TMDCs, as a direct bandgap semiconductor with strong spin-orbit, exhibit good electronic and mechanical properties in the fields of spin electronics, optoelectronics, and flexible electronics. At the same time, they also overcome the obstacles to further miniaturization of silicon transistors, such as high contact resistance, short channel effect, and high leakage current. Through theoretical calculations, it was found that, considering the long-term acoustic and optical wave scattering of carriers, among more than a dozen TMDCs materials, WS2 has a higher hole mobility of 540cm 2 V -1 s -1 Moreover, WS2 has become an ideal candidate material for field effect transistors (FETs) due to its advantages such as high carrier mobility, high thermal stability, high exciton binding energy, electrostatic integrity and no dangling bonds.

[0003] At present, the CVD method is mainly used to prepare single-layer two-dimensional WS2. However, most of the WS2 prepared by this method exhibits n-type conductivity, while the CVD preparation of high-mobility p-type two-dimensional WS2 is rarely reported, which greatly limits its application in logic complementary circuits. At present, chemical doping, electrostatic doping and other methods are mainly used to obtain p-type two-dimensional WS2.

[0004] Contact engineering is a strategy used in the preparation of two-dimensional WS2 devices. It adjusts the Fermi level at the metal / semiconductor interface by selecting metal contact materials with different work functions, thereby optimizing the injection efficiency of electrons and holes in the device. Through contact engineering, the Schottky barrier height can be reduced, making the transport of electrons and holes more balanced, and improving the performance of two-dimensional WS2 devices. However, in some cases, contact engineering may introduce new interface states that may capture or scatter carriers, thereby affecting the performance of two-dimensional WS2 devices.

[0005] Chemical doping is a common method to obtain p-type semiconductors. Some researchers use the CVD method to grow WS2, and then use the PECVD process to dope CH units (such as -CH3, -CH2-CH3) into WS2 to reduce the S vacancies in WS2 and achieve the transformation of WS2 from n-type conductivity to p-type conductivity. However, due to the non-selective adsorption of doping substances on the TMD channel surface, performance damage may also occur at the interface.

[0006] Electrostatic doping is another common method to achieve p-type conductivity in two-dimensional semiconductor functional devices. Studies have found that different regions of WS2 nanosheets can be regulated to n-type conductivity and p-type conductivity respectively through electrostatic doping, realizing an in-plane PN junction on a single WS2 nanosheet. However, the effect of electrostatic doping may be affected by environmental conditions, and its long-term stability is not as good as chemical doping. In addition, in some cases, the electric field may induce new interface states, affecting device performance.

[0007] Although some progress has been made in the preparation of p-type two-dimensional WS2, the above three preparation methods still have limitations. Field effect transistors made by contact engineering and electrostatic doping usually have complex structures and have high requirements for device preparation processes. The doping atoms in chemical doping may cause lattice distortion and affect the electronic structure and transmission characteristics. Therefore, how to improve the preparation method and directly synthesize high-quality p-type two-dimensional WS2 is of great significance for the development of the next generation of new logic complementary circuits. Summary of the invention

[0008] Technical issues to be solved

[0009] In order to avoid the shortcomings of the prior art, the present invention proposes a method for preparing a high-mobility p-type two-dimensional WS2, as well as a high-mobility p-type two-dimensional WS2 and an application thereof, aiming to adopt a novel liquid-phase assisted spatial confinement CVD method, and to prepare large-size, single-layer, p-type two-dimensional WS2 nanosheets by regulating process parameters such as deposition temperature and precursor solution concentration. The method has the advantages of strong controllability, stable process, and high preparation efficiency, and the two-dimensional WS2 has a high hole mobility, which solves the problem of low hole mobility of the two-dimensional WS2 prepared by the existing method, and provides a useful reference value for the preparation of high-quality p-type two-dimensional semiconductors.

[0010] Technical Solution

[0011] A method for preparing high-mobility p-type two-dimensional WS2, characterized in that the steps are as follows:

[0012] Step 1: Prepare a WO3 precursor solution using ammonia water as a solvent and WO3;

[0013] Step 2: Drop 0.3-0.5 ml of the precursor solution on the SiO2 surface of the SiO2 / Si substrate;

[0014] Step 3: Dry the substrate at a temperature of 80-100°C; then, place the substrate in a sleeve; then cover the substrate with another SiO2 / Si substrate and push them into the quartz tube together;

[0015] Step 4: placing a quartz boat on one side of the sleeve in the direction of carrier gas introduction; the quartz boat contains S powder;

[0016] Step 5: Place the quartz tube in a single temperature zone tube furnace, tighten the flanges at both ends of the quartz tube, and evacuate the quartz tube to a pressure of 6-10 Pa; then introduce high-purity Ar gas at a flow rate of 180-220 sccm for 5-10 minutes to make the quartz tube at normal pressure;

[0017] Step 6: Under normal pressure, adjust the Ar gas flow rate to 80-120 sccm, set the temperature control program of the single-zone tubular furnace, first heat the sleeve to 500-600°C, keep it warm for 10-25 minutes, and adjust the Ar gas flow rate to 30-60 sccm at the end of the insulation;

[0018] Step 7: When the casing is heated to 700-850°C, the heating belt of the sulfur powder is turned on and the temperature of the heating belt is set to 130-180°C; the casing is heated to 900-1000°C, and the sulfur powder is also heated to the preset temperature;

[0019] Step 8: Adjust the Ar gas to 20-30 sccm, introduce 10-20 sccm of high-purity H2 gas, and at the same time close the valve on the right side of the sleeve, and maintain the deposition conditions for 8-15 minutes; turn off the heating device and cool to room temperature with the furnace to obtain high-mobility p-type two-dimensional WS2 on the SiO2 surface of the SiO2 / Si substrate.

[0020] The SiO2 / Si substrate is ultrasonically cleaned with acetone, ethanol and deionized water for 10 to 20 minutes respectively, and then the SiO2 / Si substrate is blown dry.

[0021] The WO3 precursor solution has a WO3 concentration of 0.01-0.3 g / ml.

[0022] When preparing the WO3 precursor solution, 0.1-0.6g WO3 is prepared with ammonia water with a concentration of 10-30% and a volume of 1-100ml.

[0023] The S powder in the quartz boat is 50-70 mg.

[0024] The position distribution of the substrate and the quartz boat is that the quartz boat and the sleeve are 2-4 cm apart, the substrate in the sleeve on one side is 2-8 cm apart from the sleeve end, and the other side of the sleeve is 20-30 cm apart from the quartz tube end.

[0025] The step 3 is to place the substrate on a heating plate and dry it.

[0026] A high-mobility p-type two-dimensional WS2 prepared by the preparation method is characterized in that: the p-type two-dimensional WS2 nanosheet is a single layer, the WS2 grows laterally to achieve a large size, and there are W vacancies in the WS2, thereby introducing an acceptor energy level, so that the two-dimensional WS2 exhibits p-type conductive properties.

[0027] An application of the high-mobility p-type two-dimensional WS2 is characterized by being used to prepare p-type field effect transistors.

[0028] Using two-dimensional WS2 as the active layer, the prepared p-type field-effect transistor has a hole mobility of up to 46.87 cm 2 V -1 s -1 , the on / off ratio is 10 5 , showing excellent p-type field effect transistor characteristics.

[0029] Beneficial Effects

[0030] The present invention proposes a method for preparing a high-mobility p-type two-dimensional WS2, as well as a high-mobility p-type two-dimensional WS2 and application, by using WO3 and S as reaction precursors for preparing WS2, using ammonia water as a solvent for liquid phase assistance, and using a sleeve with a small hole at the bottom and a valve on the right for spatial confinement. Using ammonia water as a solvent, during the chemical reaction process, ammonia water can form a tungsten ammonia oxide complex with tungsten oxide, inhibit the secondary nucleation and longitudinal growth of WS2, and promote the lateral growth of WS2, which is more conducive to the preparation of large-size, single-layer two-dimensional WS2. Using a sleeve with a small hole at the bottom and a valve on the right for spatial confinement, S vapor and H2 gas can be enriched in the sleeve, creating a concentration field rich in S and H2 precursor sources, and fully contacting with the substrate surface, thereby providing sufficient precursor sources for the growth process of two-dimensional WS2. Since the reaction is carried out under a S-rich condition, there will be a certain amount of W vacancies in the two-dimensional WS2, thereby introducing an acceptor energy level, so that the two-dimensional WS2 exhibits p-type conductive properties. The p-type field effect transistor prepared with the two-dimensional WS2 prepared by the present invention has high hole mobility and a large switching ratio.

[0031] The main innovative points of the present invention are:

[0032] (1) The present invention requires a small number of equipment, and only a tubular furnace is needed to grow two-dimensional WS2, and the experimental process is easy to operate;

[0033] (2) The present invention uses ammonia water as the solvent of the liquid phase assisted method. During the reaction, ammonia water can form a tungsten ammonia oxide complex with tungsten oxide, which inhibits the secondary nucleation and longitudinal growth of WS2 and promotes the lateral growth of WS2, thereby realizing the preparation of large-size, single-layer two-dimensional WS2;

[0034] (3) The present invention uses a sleeve with a small hole at the bottom and a valve on the right side to create a concentration field rich in S and H2 precursor sources, ensuring the effective supply of precursor sources during the two-dimensional WS2 deposition process;

[0035] (4) The two-dimensional WS2 deposition process of the present invention is carried out under S-rich conditions, so WS2 contains a certain amount of W vacancies, so that the prepared two-dimensional WS2 exhibits p-type conductive properties;

[0036] (5) The present invention prepares two-dimensional WS2 on the SiO2 surface of the SiO2 / Si substrate. The prepared two-dimensional WS2 does not need to be transferred, and the substrate can be directly used to prepare field effect transistors, avoiding the cumbersome transfer process;

[0037] (6) Using the two-dimensional WS2 of the present invention as the active layer, the prepared p-type field effect transistor has a hole mobility of up to 46.87 cm 2 V -1 s -1 , the on / off ratio is 10 5 , showing excellent p-type field effect transistor characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 : Schematic diagram of the reaction apparatus.

[0039] Figure 2 : AFM test image of the grown WS2 nanosheets.

[0040] Figure 3 : STEM test image of the grown WS2 nanosheets.

[0041] Figure 4 : Semi-logarithmic coordinate transfer characteristic curve of WS2 field effect transistor.

[0042] Figure 3 The white bright spots in the middle represent W atoms. Through observation, it was found that the originally regularly arranged white bright spots disappeared in some positions, indicating that there are certain W atomic vacancies in the WS2 prepared in this experiment. The existence of W vacancies causes the prepared single-layer two-dimensional WS2 to exhibit p-type conductive properties. DETAILED DESCRIPTION

[0043] The present invention will now be further described with reference to the embodiments and the accompanying drawings:

[0044] The present invention adopts a novel liquid-phase assisted spatial confinement CVD method to prepare large-size, single-layer, p-type two-dimensional WS2 nanosheets by regulating process parameters such as deposition temperature and precursor solution concentration.

[0045] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0046] (1) The SiO2 / Si substrate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 to 20 minutes, respectively, and then the SiO2 / Si substrate was blown dry for later use.

[0047] (2) Weigh 0.1-0.6 g of WO3 and use 10-30% ammonia water with a volume of 1-100 ml as solvent to prepare a precursor solution with a WO3 concentration of 0.01-0.3 g / ml for later use.

[0048] (3) Use a small dropper to take the prepared precursor solution and drop 0.3-0.5 ml on the SiO2 surface of the SiO2 / Si substrate.

[0049] (4) Place the substrate on a heating plate to dry at a temperature of 80 to 100° C. Then, place the substrate 2 to 8 cm away from the left end of the sleeve.

[0050] (5) Take another clean SiO2 / Si substrate and place it on top of the above substrate with the SiO2 surface facing downwards. Then slowly push the sleeve into the quartz tube to a position 20 to 30 cm away from the right end.

[0051] (6) Weigh 50-70 mg of S powder into a quartz boat and push the quartz boat into the quartz tube, 2-4 cm away from the left end of the sleeve.

[0052] (7) Place the quartz tube in a single temperature zone tube furnace, tighten the flanges at both ends of the quartz tube, and evacuate the quartz tube to a pressure of 6 to 10 Pa.

[0053] (8) High-purity Ar gas at a flow rate of 180-220 sccm is introduced into the quartz tube for 5-10 minutes to bring the inside of the quartz tube to normal pressure.

[0054] (9) Under normal pressure, adjust the Ar gas flow rate to 80-120 sccm, set the temperature control program of the single-zone tubular furnace, first heat the sleeve to 500-600°C, keep it warm for 10-25 minutes, and adjust the Ar gas flow rate to 30-60 sccm at the end of the insulation.

[0055] (10) When the casing is heated to 700-850°C, the heating belt of the sulfur powder is turned on and the temperature of the heating belt is set to 130-180°C.

[0056] (11) The casing is then heated to 900-1000°C and the sulfur powder is simultaneously heated to a preset temperature.

[0057] (12) Adjust the Ar gas to 20-30 sccm, introduce 10-20 sccm of high-purity H2 gas, and at the same time close the valve on the right side of the sleeve, maintaining the deposition conditions for 8-15 minutes.

[0058] (13) Turn off the heating device, cool to room temperature with the furnace, and take out the sample. Specific implementation method:

[0060] Example 1:

[0061] (1) The SiO2 / Si substrate was ultrasonically cleaned with acetone, ethanol, and deionized water for 10 min respectively, and then the SiO2 / Si substrate was blown dry for later use.

[0062] (2) Weigh 0.1 g of WO3 and use 10% ammonia water with a volume of 1 ml as solvent to prepare a precursor solution with a WO3 concentration of 0.01 g / ml for later use.

[0063] (3) Use a small dropper to take the prepared precursor solution and drop 0.3 ml on the SiO2 surface of the SiO2 / Si substrate.

[0064] (4) The substrate was placed on a heating plate for drying at a temperature of 80° C. Then, the substrate was placed 2 cm away from the left end of the sleeve.

[0065] (5) Take another clean SiO2 / Si substrate and place it parallel to the above substrate with the SiO2 surface facing downward. Then slowly push the sleeve into the quartz tube to a position 20 cm away from the right end.

[0066] (6) Weigh 50 mg of S powder into a quartz boat and push the quartz boat into the quartz tube, 2 cm away from the left end of the sleeve.

[0067] (7) Place the quartz tube in a single-temperature zone tubular furnace, tighten the flanges at both ends of the quartz tube, and evacuate the quartz tube to a pressure of 6 Pa.

[0068] (8) High-purity Ar gas at a flow rate of 180 sccm is introduced into the quartz tube until the inside of the quartz tube is maintained at normal pressure.

[0069] (9) While maintaining normal pressure, adjust the Ar gas flow rate to 80 sccm, set the temperature control program of the single-zone tubular furnace, first heat the sleeve to 500°C, then keep it warm for 10 minutes, and adjust the Ar gas flow rate to 30 sccm at the end of the insulation.

[0070] (10) When the casing is heated to 700°C, the heating belt of the sulfur powder is turned on and the temperature is set to 130°C.

[0071] (11) The casing is then heated to 900°C and the sulfur powder is simultaneously heated to a preset temperature.

[0072] (12) Adjust the Ar gas to 20 sccm, introduce 10 sccm of high-purity H2 gas, and at the same time close the valve on the right side of the sleeve, and maintain the deposition conditions for 8 minutes.

[0073] (13) Turn off the heating device, cool to room temperature with the furnace, and take out the sample.

[0074] Example 2:

[0075] (1) The SiO2 / Si substrate was ultrasonically cleaned with acetone, ethanol, and deionized water for 20 min respectively, and then the SiO2 / Si substrate was blown dry for later use.

[0076] (2) Weigh 0.6 g of WO3 and use 30% ammonia water with a volume of 100 ml as solvent to prepare a precursor solution with a WO3 concentration of 0.3 g / ml for later use.

[0077] (3) Use a small dropper to take the prepared precursor solution and drop 0.4 ml on the SiO2 surface of the SiO2 / Si substrate.

[0078] (4) The substrate was placed on a heating plate for drying at a temperature of 90° C. Then, the substrate was placed 5 cm away from the left end of the sleeve.

[0079] (5) Take another SiO2 / Si clean substrate and place it on top of the above substrate with the SiO2 surface facing downwards. Then slowly push the sleeve into the quartz tube to a position 30 cm away from the right end.

[0080] (6) Weigh 70 mg of S powder into a quartz boat and push the quartz boat into the quartz tube, 4 cm away from the left end of the sleeve.

[0081] (7) Place the quartz tube in a single temperature zone tube furnace, tighten the flanges at both ends of the quartz tube, and evacuate the quartz tube to a pressure of 8 Pa.

[0082] (8) High-purity Ar gas at a flow rate of 200 sccm is introduced into the quartz tube until the inside of the quartz tube is maintained at normal pressure.

[0083] (9) While maintaining normal pressure, adjust the Ar gas flow rate to 120 sccm, set the temperature control program of the single-zone tubular furnace, first heat the sleeve to 550°C, then keep it warm for 20 minutes, and adjust the Ar gas flow rate to 50 sccm at the end of the insulation.

[0084] (10) When the sleeve is heated to 850°C, the heating belt of the sulfur powder is turned on and the temperature is set to 180°C.

[0085] (11) The casing is then heated to 1000°C and the sulfur powder is simultaneously heated to a preset temperature.

[0086] (12) Adjust the Ar gas to 30 sccm, introduce 20 sccm of high-purity H2 gas, and at the same time close the valve on the right side of the sleeve, and maintain the deposition conditions for 15 minutes.

[0087] (13) Turn off the heating device, cool to room temperature with the furnace, and take out the sample.

[0088] Example 3:

[0089] (1) The SiO2 / Si substrate was ultrasonically cleaned with acetone, ethanol, and deionized water for 15 min respectively, and then the SiO2 / Si substrate was blown dry for later use.

[0090] (2) Weigh 0.3 g of WO3 and use 50 ml of 20% ammonia water as solvent to prepare a precursor solution with a WO3 concentration of 0.1 g / ml for later use.

[0091] (3) Use a small dropper to take the prepared precursor solution and drop 0.5 ml on the SiO2 surface of the SiO2 / Si substrate.

[0092] (4) The substrate was placed on a heating plate for drying at a temperature of 90° C. Then, the substrate was placed 8 cm away from the left end of the sleeve.

[0093] (5) Take another clean SiO2 / Si substrate and place it parallel to the above substrate with the SiO2 surface facing downward. Then slowly push the sleeve into the quartz tube to a position 25 cm away from the right end.

[0094] (6) Weigh 60 mg of S powder into a quartz boat and push the quartz boat into the quartz tube, 3 cm away from the left end of the sleeve.

[0095] (7) Place the quartz tube in a single temperature zone tubular furnace, tighten the flanges at both ends of the quartz tube, and evacuate the quartz tube to a pressure of 10 Pa.

[0096] (8) High-purity Ar gas at a flow rate of 200 sccm is introduced into the quartz tube until the inside of the quartz tube is maintained at normal pressure.

[0097] (9) While maintaining normal pressure, adjust the Ar gas flow rate to 120 sccm, set the temperature control program of the single-zone tubular furnace, first heat the sleeve to 550°C, then keep it warm for 25 minutes, and adjust the Ar gas flow rate to 30 sccm at the end of the insulation.

[0098] (10) When the sleeve is heated to 775°C, the heating belt of the sulfur powder is turned on and the temperature is set to 150°C.

[0099] (11) The sleeve is then heated to 960°C, and the sulfur powder is simultaneously heated to a preset temperature.

[0100] (12) Adjust the Ar gas to 25 sccm, introduce 15 sccm of high-purity H2 gas, and at the same time close the valve on the right side of the sleeve, and maintain the deposition conditions for 12 minutes.

[0101] (13) Turn off the heating device, cool to room temperature with the furnace, and take out the sample.

[0102] This method has the advantages of strong controllability, stable process, and high preparation efficiency. The two-dimensional WS2 has a high hole mobility, which solves the problem of low hole mobility of two-dimensional WS2 prepared by existing methods, and provides a useful reference value for the preparation of high-quality p-type two-dimensional semiconductors.

Claims

1. A method for preparing a high-mobility p-type two-dimensional WS2, characterized in that Here are the steps: Step 1: Prepare a WO3 precursor solution using ammonia water as a solvent and WO3; Step 2: Drop 0.3-0.5 ml of the precursor solution on the SiO2 surface of the SiO2 / Si substrate; Step 3: Dry the substrate at a temperature of 80-100°C; then, place the substrate in a sleeve; then cover the substrate with another SiO2 / Si substrate and push them into the quartz tube together; Step 4: placing a quartz boat on one side of the sleeve in the direction of carrier gas introduction; the quartz boat contains S powder; Step 5: Place the quartz tube in a single temperature zone tube furnace, tighten the flanges at both ends of the quartz tube, and evacuate the quartz tube to a pressure of 6-10 Pa; then introduce high-purity Ar gas at a flow rate of 180-220 sccm for 5-10 minutes to make the quartz tube at normal pressure; Step 6: Under normal pressure, adjust the Ar gas flow rate to 80-120 sccm, set the temperature control program of the single-zone tubular furnace, first heat the sleeve to 500-600°C, keep it warm for 10-25 minutes, and adjust the Ar gas flow rate to 30-60 sccm at the end of the insulation; Step 7: When the casing is heated to 700-850°C, the heating belt of the sulfur powder is turned on and the temperature of the heating belt is set to 130-180°C; the casing is heated to 900-1000°C, and the sulfur powder is also heated to the preset temperature; Step 8: Adjust the Ar gas to 20-30 sccm, introduce 10-20 sccm of high-purity H2 gas, and at the same time close the valve on the right side of the sleeve, and maintain the deposition conditions for 8-15 minutes; turn off the heating device and cool to room temperature with the furnace to obtain high-mobility p-type two-dimensional WS2 on the SiO2 surface of the SiO2 / Si substrate.

2. The method for preparing high-mobility p-type two-dimensional WS2 according to claim 1, characterized in that: The SiO2 / Si substrate is ultrasonically cleaned with acetone, ethanol and deionized water for 10 to 20 minutes respectively, and then the SiO2 / Si substrate is blown dry.

3. The method for preparing high-mobility p-type two-dimensional WS2 according to claim 1, characterized in that: The WO3 precursor solution has a WO3 concentration of 0.01-0.3 g / ml.

4. The method for preparing a high-mobility p-type two-dimensional WS2 according to claim 1 or 3, characterized in that: When preparing the WO3 precursor solution, 0.1-0.6g WO3 is prepared with ammonia water with a concentration of 10-30% and a volume of 1-100ml.

5. The method for preparing high-mobility p-type two-dimensional WS2 according to claim 1, characterized in that: The S powder in the quartz boat is 50-70 mg.

6. The method for preparing high-mobility p-type two-dimensional WS2 according to claim 1, characterized in that: The position distribution of the substrate and the quartz boat is that the quartz boat and the sleeve are 2-4 cm apart, the substrate in the sleeve on one side is 2-8 cm apart from the sleeve end, and the other side of the sleeve is 20-30 cm apart from the quartz tube end.

7. The method for preparing high-mobility p-type two-dimensional WS2 according to claim 1, characterized in that: The step 3 is to place the substrate on a heating plate and dry it.

8. A high-mobility p-type two-dimensional WS2 prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The p-type two-dimensional WS2 nanosheet is a single layer, and WS2 grows laterally to achieve a large size. There are W vacancies in the WS2, thereby introducing acceptor energy levels, so that the two-dimensional WS2 exhibits p-type conductive properties.

9. An application of the high-mobility p-type two-dimensional WS2 according to claim 8, characterized in that: Used to prepare p-type field effect transistors.

10. The use of the high-mobility p-type two-dimensional WS2 according to claim 9, characterized in that: Using two-dimensional WS2 as the active layer, the prepared p-type field-effect transistor has a hole mobility of up to 46.87 cm 2 V -1 s -1 , the on / off ratio is 10 5 , showing excellent p-type field effect transistor characteristics.

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