Field effect transistor based on phenylselenol modified WSe2 Van der Waals film and preparation method thereof

Abstract

The invention relates to the technical field of field effect transistors, in particular to a field effect transistor based on a benzeneselenol modified WSe2 Van der Waals thin film and a preparation method of the field effect transistor based on the benzeneselenol modified WSe2 Van der Waals thin film, and the field effect transistor takes the benzeneselenol modified WSe2 Van der Waals thin film as a semiconductor channel of the field effect transistor. The gate layer, the insulating layer, the semiconductor channel layer and the electrode layer are sequentially arranged; the semiconductor channel layer adopts a WSe2 Van der Waals film modified by phenylselenol, and the electrode layer comprises a source electrode and a drain electrode which are respectively arranged at two sides of the semiconductor channel layer. By modifying the WSe2 Van der Waals thin film with the phenylselenol, the quality of the WSe2 Van der Waals thin film is improved, meanwhile, the energy level structure of the field effect transistor is adjusted, the Schottky barrier between contact metal and a semiconductor channel is reduced, the transmission rate of current carriers is increased, and the performance of the device is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of field effect transistors, and in particular to a field effect transistor based on phenylselenol-modified WSe2 van der Waals thin film and a preparation method thereof. Background Art

[0002] With the development of science and technology, integrated circuit technology has become the foundation of information industry and modern science and technology, and has promoted the rapid development of the information age. As the basic unit of integrated circuits, field effect transistors play an important role in the field of information science and technology. At present, the industrialized field effect transistors mainly use silicon as the channel material. Silicon-based transistors are widely used in computers, communications, televisions, and audio due to their low power consumption, high reliability, and long life. With the development and changes in scientific and technological needs, transistors need to achieve miniaturization, intelligence, and high integration. This requires an increase in the number of transistors that can be accommodated on integrated circuits. The smaller the size of silicon-based transistors, the more prominent their short channel effects will be, resulting in large leakage currents and high energy consumption, which seriously weakens the electrical performance of silicon-based transistors, thereby limiting the final integration and power consumption of silicon-based transistors in the future. Therefore, it is urgent to develop new channel materials to replace traditional silicon-based materials. Two-dimensional materials have ultra-thin atomic layer thickness and a flat surface without dangling bonds, which can avoid unnecessary scattering and have become a strong candidate for constructing high-integration circuits in the future.

[0003] Two-dimensional transition metal dichalcogenides (TMDs) are very promising transistor channel materials. Due to their advantages such as atomically thin layer thickness, no dangling bonds on the surface, and tunable band gap, they can avoid the charge scattering effect caused by defects or traps, and are therefore widely used in various electronic devices. In particular, van der Waals films formed by TMDs (such as molybdenum disulfide MoS2, tungsten disulfide WS2, tungsten diselenide WSe2, etc.) nanosheets dispersed in solution have great potential for the application of high-performance thin-film field-effect devices, and are very promising in the field of large-scale integrated circuits. At present, representative p-type two-dimensional semiconductor materials with high mobility are black phosphorus and WSe2, but black phosphorus has poor chemical stability and oxidation resistance and is not suitable for solution processes; WSe2 has a suitable band gap and excellent stability, with a band gap between 1.2-1.65eV, and has higher carrier transport performance than MoS2. Theoretical predictions show that its hole mobility can reach up to 839cm 2 V -1 s -1 Therefore, WSe2 has great prospects in the application of high-performance complementary logic integrated circuits and pn junction devices.

[0004] WSe2 bulk materials can be exfoliated into nanosheets by liquid phase exfoliation, but it is difficult to exfoliate nanosheets due to the large interlayer van der Waals interaction force, and many selenium vacancy defects will be generated on the surface of the nanosheets when exfoliating, which affects the surface quality of the van der Waals film formed by WSe2 nanosheets. These defects will cause non-radiative recombination in charge carriers to a large extent, making the carrier transport capacity of the prepared WSe2 thin film transistor poor. In addition, the Schottky barrier height between the contact electrode and the semiconductor channel material is high. These factors seriously limit the electrical performance of the thin film field effect transistor. Therefore, it is particularly important to improve the electrical performance of the device by reducing the defect density and reducing the Schottky barrier height at the contact interface. Summary of the invention

[0005] In order to solve the problem in the prior art that the high defect density on the surface of the van der Waals film formed by WSe2 nanosheets leads to a high Schottky barrier height, which limits the electrical properties of the thin film field effect transistor, the present invention proposes a method for preparing a field effect transistor using a WSe2 van der Waals film modified with phenylselenol, wherein the selenium element therein fills the selenium vacancies generated during stripping and forms new covalent bonds with tungsten atoms to restore the original structure of the WSe2 crystal, reduce the roughness and defect density of the van der Waals film surface, improve the energy level contact, and reduce the Schottky barrier between the contact metal and the channel, thereby improving the electrical properties of the field effect transistor.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a field effect transistor based on WSe2 van der Waals film modified by phenylselenol, using the WSe2 van der Waals film modified by phenylselenol as the semiconductor channel of the field effect transistor.

[0007] The field effect transistor based on phenylselenol-modified WSe2 van der Waals film comprises a gate layer, an insulating layer, a semiconductor channel layer and an electrode layer arranged in sequence; the semiconductor channel layer adopts the WSe van der Waals film modified with phenylselenol, and the electrode layer comprises a source electrode and a drain electrode respectively arranged on both sides of the semiconductor channel layer.

[0008] The gate layer material is silicon, the insulating layer material is silicon dioxide, and the source electrode and the drain electrode material are gold.

[0009] The thickness of the semiconductor channel layer is 20-60 nm.

[0010] In addition, the present invention also provides a method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals film, comprising the following steps:

[0011] Step 1, irradiate a clean silicon / silicon dioxide substrate under ultraviolet light for 10 to 20 minutes, and then spin-coat the two-dimensional semiconductor WSe2 ink prepared by intercalation reaction in a double-electrode electrochemical cell on the clean silicon / silicon dioxide substrate. The spin coating method is static spin coating. After the spin coating is completed, annealing is performed on a heating table to finally form a WSe2 van der Waals film;

[0012] Step 2, preparing an isopropanol solution of phenylselenol with a concentration of 10 to 150 mM;

[0013] Step 3, immersing the device obtained in step 1 in the phenylselenol solution prepared in step 2, and after immersion, rinsing the device with an isopropanol solution, and after the solution evaporates slowly, annealing is performed to finally prepare a WSe2 van der Waals film treated with phenylselenol;

[0014] Step 4: evaporate a metal electrode on the surface of the WSe2 van der Waals film to form a source electrode and a drain electrode, thereby completing the preparation of the field effect transistor.

[0015] In step 1, the preparation method of the two-dimensional semiconductor WSe2 ink is:

[0016] Step 1.1, using two-dimensional semiconductor WSe2 as cathode, graphite rod as anode, a mixed solution of 0.2-0.3g tetraheptylammonium bromide and 40mL acetonitrile as electrolyte, the applied voltage is set to 25V, and the intercalation process is carried out for 3-5h;

[0017] Step 1.2, repeatedly washing the material obtained in step 1 with an ethanol solution to remove electrolytes, blowing the washed material dry and dispersing it in an 8 mg / mL polyvinyl pyrrolidone / nitromethyl pyrrolidone solution, and then performing ultrasonic stripping treatment in a plasma cleaning machine with a power of 100 W for 5 to 10 minutes;

[0018] Step 1.3, centrifuge the solution after ultrasound, first centrifuge at 1000 rpm / min for 10-15 minutes, then take the supernatant, then add n-hexane and dichloromethane solutions in a ratio of 1:1:1 to mix to obtain a mixed solution, centrifuge the mixed solution at 10000 rpm / min for 10 minutes to obtain a precipitate, add isopropanol solution to the precipitate, and then centrifuge at 1000 rpm / min for 10 minutes to obtain the supernatant, add isopropanol solution to the supernatant again to mix, centrifuge at 10000 rpm / min for 10 minutes to obtain the precipitate, finally add isopropanol solution to the precipitate and centrifuge at 1000 rpm / min for 10 minutes to obtain the supernatant, and finally obtain WSe2 nanosheets of appropriate size dispersed in the isopropanol solution, which is the obtained two-dimensional semiconductor WSe2 ink.

[0019] In the step 1.3, the steps of adding isopropanol solution to the supernatant to mix, centrifuging at a speed of 10000 rpm / min for 10 min and taking the precipitate, and finally adding isopropanol solution to the precipitate and centrifuging at 1000 rpm / min for 10 min and taking the supernatant are repeated 1 to 2 times, each time adding 1-3 mL of isopropanol solution.

[0020] In the step 1, the spin coating speed is 1500 rpm / min, the spin coating time is 20 s, and the number of spin coatings is 5 to 14 times; after the spin coating is completed, annealing is performed on a heating table at 200° C. for 15 minutes to finally form a WSe2 van der Waals film with a thickness of 20 to 60 nm.

[0021] In step 3, the soaking time is 24 to 36 hours; the annealing temperature is 80 to 210° C., and the annealing time is 30 minutes.

[0022] In the step 4, the thickness of the evaporated metal electrode is 50-100 nm.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention modifies the WSe2 van der Waals film with phenylselenol. The selenium element in the phenylselenol molecule repairs the selenium vacancy defects generated during the solution stripping process and forms a new covalent bond with the tungsten element, thereby reducing the film defect density and restoring the original structure of the WSe2 crystal, improving the quality of the WSe2 van der Waals film, adjusting the energy level structure of the field effect transistor, reducing the Schottky barrier between the contact metal and the semiconductor channel, and increasing the carrier transmission rate. Compared with the unmodified WSe2 thin film transistor, the device has a carrier mobility (μ) and a current switching ratio (I ON / I OFF ), threshold voltage (V TH The electrical performance parameters such as ) and subthreshold swing (SS) have been improved. The carrier mobility of the device has increased from 1.35×10 -4 cm 2 V -1 s -1 Increased to 0.24cm 2 V -1 s -1 The current switching ratio is also increased from 10 2 Raised to 10 5 . BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a field effect transistor based on WSe2 van der Waals thin film prepared by the present invention;

[0026] Figure 2A schematic diagram of the three-dimensional structure of a field effect transistor based on a WSe2 van der Waals thin film prepared by the present invention;

[0027] Figure 3 The AFM images of the original WSe2 van der Waals film and the WSe2 van der Waals film modified with phenylselenol. After modification, the surface roughness of the film is reduced from 14.79nm to 11.88nm.

[0028] Figure 4 The transfer characteristic curves of field effect transistors prepared based on the original and phenylselenol-modified WSe2 van der Waals films, where the horizontal axis represents the applied gate-source voltage and the vertical axis represents the absolute value of the measured drain-source current. Figure 3 It can be clearly seen that the carrier mobility and current switching ratio of the device have been significantly improved. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] Embodiment 1

[0031] like Figures 1-2 As shown, the first embodiment of the present invention provides a field effect transistor based on a WSe2 van der Waals film modified with phenylselenol, using the WSe2 van der Waals film modified with phenylselenol as the semiconductor channel of the field effect transistor. Specifically, the field effect transistor includes a gate layer 1, an insulating layer 2, a semiconductor channel layer 3 and an electrode layer 4 arranged in sequence; the semiconductor channel layer 3 uses a WSe2 van der Waals film modified with phenylselenol, and the electrode layer 4 includes a source electrode 5 and a drain electrode 6 respectively arranged on both sides of the semiconductor channel layer 3.

[0032] Specifically, in this embodiment, the gate layer 1 is made of silicon, the insulating layer 2 is made of silicon dioxide, and the source electrode 5 and the drain electrode 6 are made of gold.

[0033] Furthermore, in this embodiment, the thickness of the semiconductor channel layer 3 is 20-60 nm, and the thickness of the electrode layer 4 is 50-100 nm.

[0034] Embodiment 2

[0035] Embodiment 2 of the present invention provides a method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film, comprising the following steps:

[0036] Step 1. Irradiate a clean silicon / silicon dioxide substrate under ultraviolet light for 10 to 20 minutes, and then spin-coat the two-dimensional semiconductor WSe2 ink prepared by intercalation reaction in a double-electrode electrochemical cell on the clean silicon / silicon dioxide substrate. The spin coating method is static spin coating. After spin coating, annealing is performed on a heating table to finally form a WSe2 van der Waals film.

[0037] Specifically, in step 1, the preparation method of the two-dimensional semiconductor WSe2 ink is:

[0038] Step 1.1, use the two-dimensional semiconductor WSe2 as the cathode, the graphite rod as the anode, and a mixed solution of 0.2-0.3 g tetraheptylammonium bromide and 40 mL acetonitrile as the electrolyte. The applied voltage is set to 25 V, and the intercalation process is carried out for 3-5 hours.

[0039] Step 1.2, the material obtained in step 1 is repeatedly washed with an ethanol solution to remove electrolytes, the washed material is blown dry and dispersed in an 8 mg / mL polyvinyl pyrrolidone / nitromethyl pyrrolidone (PVP / NMP) solution, and then subjected to ultrasonic stripping in a plasma cleaning machine with a power of 100 W for 3 to 10 minutes;

[0040] Step 1.3, centrifuge the solution after ultrasound, first centrifuge at 1000 rpm / min for 10-15 minutes, then take the supernatant, then add n-hexane and dichloromethane solutions in a ratio of 1:1:1 to mix to obtain a mixed solution, centrifuge the mixed solution at 10000 rpm / min for 10 minutes to obtain a precipitate, add isopropanol solution to the precipitate, and then centrifuge at 1000 rpm / min for 10 minutes to obtain the supernatant, add isopropanol solution to the supernatant again to mix, centrifuge at 10000 rpm / min for 10 minutes to obtain the precipitate, finally add isopropanol solution to the precipitate and centrifuge at 1000 rpm / min for 10 minutes to obtain the supernatant, and finally obtain WSe2 nanosheets of appropriate size dispersed in the isopropanol solution, which is the obtained two-dimensional semiconductor WSe2 ink.

[0041] Further, in the step 1.3, the step of adding isopropanol solution to the supernatant for mixing, centrifuging at a speed of 10000 rpm / min for 10 min and then taking the precipitate, and finally adding isopropanol solution to the precipitate and centrifuging at 1000 rpm / min for 10 min and then taking the supernatant is repeated 1 to 2 times until WSe2 nanosheets of appropriate size are obtained, which are dispersed in the isopropanol solution to form a two-dimensional semiconductor WSe2 ink; further, in the step 1.3, 1-3 mL of isopropanol solution is added each time.

[0042] Specifically, in step 1, the spin coating time is 20s, the spin coating speed is 1500rpm / min, and the number of spin coating is 5 to 14 times; after the spin coating is completed, annealing is performed on a heating table at 200°C for 15min to finally form a WSe2 van der Waals film.

[0043] Step 2: prepare an isopropanol solution of phenylselenol with a concentration of 50-100 mM.

[0044] Step 3, immersing the device obtained in step 1 in the phenylselenol solution prepared in step 2. After immersion, the device is rinsed with an isopropanol solution. After the solution evaporates slowly, annealing is performed to finally prepare a WSe2 van der Waals film treated with phenylselenol.

[0045] In the step 3, the device is immersed in the prepared phenylselenol solution for 24 to 36 hours; the temperature of the annealing treatment is 80 to 210° C., and the annealing time is 30 minutes.

[0046] Step 4: Deposit a metal electrode on the surface of the WSe2 van der Waals film to form a source electrode (5) and a drain electrode (6), thereby completing the preparation of the field effect transistor. In step 4, the thickness of the deposited metal electrode is 50 to 100 nm, and the deposition rate is

[0047] Embodiment 3

[0048] Embodiment 3 of the present invention provides a method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film, comprising the following steps:

[0049] 1. Prepare two-dimensional semiconductor WSe2 ink by intercalation reaction through a double-electrode electrochemical cell. The specific method is as follows:

[0050] The two-dimensional semiconductor WSe2 was used as the cathode, the graphite rod was used as the anode, and a mixed solution of 0.2 g tetraheptyl ammonium bromide and 40 mL acetonitrile was used as the electrolyte. The applied voltage was set to 25 V, and the intercalation process was carried out for 3 h.

[0051] After the intercalation was completed, the material was repeatedly washed with an ethanol solution, dried and dispersed in an 8 mg / mL polyvinylpyrrolidone / nitromethylpyrrolidone (PVP / NMP) solution, and then subjected to ultrasonic stripping in a plasma cleaner with a power of 100 W for 10 min.

[0052] The solution after ultrasound was centrifuged, first centrifuged at 1000 rpm / min for 10 min, then the supernatant was taken, and then n-hexane and dichloromethane solutions were added in a ratio of 1:1:1 to mix, and then the precipitate was taken after centrifugation at 10000 rpm / min for 10 min, and isopropanol solution was added to the precipitate, and then centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and then isopropanol solution was added to mix, and then centrifuged at 10000 rpm / min for 10 min, and the precipitate was taken, and finally 2 mL of isopropanol solution was added and centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and finally WSe2 nanosheets of appropriate size were obtained, which were dispersed in isopropanol solution to obtain two-dimensional semiconductor WSe2 ink.

[0053] 2. Irradiate the clean Si / SiO2 substrate under UV light for 15 minutes, and spin-coat the prepared two-dimensional semiconductor WSe2 ink on the clean Si / SiO2 substrate. The spin coating method is static spin coating, the rotation speed is 1500rpm / min, the spin coating time is 20s, and the number of spin coatings is 7 times. After the spin coating is completed, anneal it on a heating table at 200℃ for 15 minutes, and finally form a WSe2 van der Waals film of about 45nm;

[0054] 3. Prepare an isopropanol solution of 100 mM phenylselenol, immerse the formed WSe2 van der Waals film in the prepared phenylselenol solution for 24 hours, rinse with isopropanol solution, and after the solution evaporates slowly, anneal at a high temperature of 150°C for 30 minutes to finally prepare a WSe2 van der Waals film treated with phenylselenol.

[0055] 4. A metal electrode was deposited on the surface of the WSe2 van der Waals film obtained above to complete the preparation of the field effect transistor. The thickness of the deposited gold film was 60 nm, and the deposition rate was

[0056] Embodiment 4:

[0057] Embodiment 4 of the present invention provides a method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film, comprising the following steps:

[0058] 1. Prepare two-dimensional semiconductor WSe2 ink by intercalation reaction through a double-electrode electrochemical cell. The specific method is as follows:

[0059] The two-dimensional semiconductor WSe2 was used as the cathode, the graphite rod as the anode, and a mixed solution of 0.2 g tetraheptyl ammonium bromide and 40 mL acetonitrile as the electrolyte. The applied voltage was set to 25 V, and the intercalation process was carried out for 5 h.

[0060] After the intercalation was completed, the material was repeatedly washed with an ethanol solution, dried and dispersed in an 8 mg / mL polyvinylpyrrolidone / nitromethylpyrrolidone (PVP / NMP) solution, and then subjected to ultrasonic stripping in a plasma cleaner with a power of 100 W for 5 min.

[0061] The solution after ultrasound was centrifuged, first centrifuged at 1000 rpm / min for 10 min, then the supernatant was taken, and then n-hexane and dichloromethane solutions were added in a ratio of 1:1:1 to mix, and then the precipitate was taken after centrifugation at 10000 rpm / min for 10 min, and isopropanol solution was added to the precipitate, and then centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and then isopropanol solution was added to mix, and then centrifuged at 10000 rpm / min for 10 min, and the precipitate was taken, and finally 2 mL of isopropanol solution was added and centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and finally WSe2 nanosheets of appropriate size were obtained, which were dispersed in isopropanol solution to obtain two-dimensional semiconductor WSe2 ink.

[0062] 2. Irradiate the clean Si / SiO2 substrate under UV light for 15 minutes, and spin-coat the prepared two-dimensional semiconductor WSe2 ink on the clean Si / SiO2 substrate. The spin coating method is static spin coating, the rotation speed is 1500rpm / min, the spin coating time is 20s, and the number of spin coatings is 10 times. After the spin coating is completed, anneal it on a heating table at 200℃ for 15 minutes, and finally form a WSe2 van der Waals film of about 50nm;

[0063] 3. Prepare an isopropanol solution of 50 mM phenylselenol, soak the formed WSe2 van der Waals film in the prepared phenylselenol solution for 32 hours, rinse with isopropanol solution, and after the solution evaporates slowly, anneal at a high temperature of 120°C for 30 minutes to finally prepare a WSe2 van der Waals film treated with phenylselenol.

[0064] 4. A metal electrode was deposited on the surface of the WSe2 van der Waals film obtained above to complete the preparation of the field effect transistor. The thickness of the deposited gold film was 65 nm, and the deposition rate was

[0065] Embodiment 5

[0066] Embodiment 5 of the present invention provides a method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film, comprising the following steps:

[0067] 1. Prepare two-dimensional semiconductor WSe2 ink by intercalation reaction through a double-electrode electrochemical cell. The specific method is as follows:

[0068] The two-dimensional semiconductor WSe2 was used as the cathode, the graphite rod as the anode, and a mixed solution of 0.3 g tetraheptyl ammonium bromide and 40 mL acetonitrile as the electrolyte. The applied voltage was set to 25 V, and the intercalation process was carried out for 5 h.

[0069] After the intercalation was completed, the material was repeatedly washed with an ethanol solution, dried and dispersed in an 8 mg / mL polyvinylpyrrolidone / nitromethylpyrrolidone (PVP / NMP) solution, and then subjected to ultrasonic stripping in a plasma cleaner with a power of 100 W for 5 min.

[0070] The solution after ultrasound was centrifuged, first centrifuged at 1000 rpm / min for 10 min, then the supernatant was taken, and then n-hexane and dichloromethane solutions were added in a ratio of 1:1:1 to mix, and then the precipitate was taken after centrifugation at 10000 rpm / min for 10 min, and isopropanol solution was added to the precipitate, and then centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and then isopropanol solution was added to mix, and then centrifuged at 10000 rpm / min for 10 min, and the precipitate was taken, and finally 2 mL of isopropanol solution was added and centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and finally WSe2 nanosheets of appropriate size were obtained, which were dispersed in isopropanol solution to obtain two-dimensional semiconductor WSe2 ink.

[0071] 2. Irradiate the clean Si / SiO2 substrate under UV light for 15 minutes, and spin-coat the prepared two-dimensional semiconductor WSe2 ink on the clean Si / SiO2 substrate. The spin coating method is static spin coating, the rotation speed is 1500rpm / min, the spin coating time is 20s, and the number of spin coatings is 8 times. After the spin coating is completed, anneal it on a heating table at 200℃ for 15 minutes, and finally form a WSe2 van der Waals film of about 40nm;

[0072] 3. Prepare an isopropanol solution of 100 mM phenylselenol, soak the formed WSe2 van der Waals film in the prepared phenylselenol solution for 32 hours, rinse with isopropanol solution, and after the solution evaporates slowly, anneal at 80°C for 30 minutes to finally prepare a WSe2 van der Waals film treated with phenylselenol.

[0073] 4. A metal electrode was deposited on the surface of the WSe2 van der Waals film obtained above to complete the preparation of the field effect transistor. The thickness of the deposited gold film was 50 nm and the deposition rate was

[0074] Embodiment 6

[0075] Embodiment 5 of the present invention provides a method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film, comprising the following steps:

[0076] 1. Prepare two-dimensional semiconductor WSe2 ink by intercalation reaction through a double-electrode electrochemical cell. The specific method is as follows:

[0077] The two-dimensional semiconductor WSe2 was used as the cathode, the graphite rod as the anode, and a mixed solution of 0.3 g tetraheptyl ammonium bromide and 40 mL acetonitrile as the electrolyte. The applied voltage was set to 25 V, and the intercalation process was carried out for 5 h.

[0078] After the intercalation was completed, the material was repeatedly washed with an ethanol solution, dried and dispersed in an 8 mg / mL polyvinylpyrrolidone / nitromethylpyrrolidone (PVP / NMP) solution, and then subjected to ultrasonic stripping in a plasma cleaner with a power of 100 W for 5 min.

[0079] The solution after ultrasound was centrifuged, first centrifuged at 1000 rpm / min for 10 min, then the supernatant was taken, and then n-hexane and dichloromethane solutions were added in a ratio of 1:1:1 to mix, and then the precipitate was taken after centrifugation at 10000 rpm / min for 10 min, and isopropanol solution was added to the precipitate, and then centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and then isopropanol solution was added to mix, and then centrifuged at 10000 rpm / min for 10 min, and the precipitate was taken, and finally 2 mL of isopropanol solution was added and centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and finally WSe2 nanosheets of appropriate size were obtained, which were dispersed in isopropanol solution to obtain two-dimensional semiconductor WSe2 ink.

[0080] 2. Irradiate the clean Si / SiO2 substrate under UV light for 15 minutes, and spin-coat the prepared two-dimensional semiconductor WSe2 ink on the clean Si / SiO2 substrate. The spin coating method is static spin coating, the rotation speed is 1500rpm / min, the spin coating time is 20s, and the number of spin coatings is 8 times. After the spin coating is completed, anneal it on a heating table at 200℃ for 15 minutes, and finally form a WSe2 van der Waals film of about 40nm;

[0081] 3. Prepare an isopropanol solution of 100 mM phenylselenol, soak the formed WSe2 van der Waals film in the prepared phenylselenol solution for 32 hours, rinse with isopropanol solution, and after the solution evaporates slowly, anneal at a high temperature of 180°C for 30 minutes to finally prepare a WSe2 van der Waals film treated with phenylselenol.

[0082] 4. A metal electrode was deposited on the surface of the WSe2 van der Waals film obtained above to complete the preparation of the field effect transistor. The thickness of the deposited gold film was 50 nm and the deposition rate was

[0083] Embodiment 7

[0084] Embodiment 7 of the present invention provides a method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film, comprising the following steps:

[0085] 1. Prepare two-dimensional semiconductor WSe2 ink by intercalation reaction through a double-electrode electrochemical cell. The specific method is as follows:

[0086] The two-dimensional semiconductor WSe2 was used as the cathode, the graphite rod as the anode, and a mixed solution of 0.3 g tetraheptyl ammonium bromide and 40 mL acetonitrile as the electrolyte. The applied voltage was set to 25 V, and the intercalation process was carried out for 5 h.

[0087] After the intercalation was completed, the material was repeatedly washed with an ethanol solution, dried and dispersed in an 8 mg / mL polyvinylpyrrolidone / nitromethylpyrrolidone (PVP / NMP) solution, and then subjected to ultrasonic stripping in a plasma cleaner with a power of 100 W for 5 min.

[0088] The solution after ultrasound was centrifuged, first centrifuged at 1000 rpm / min for 10 min, then the supernatant was taken, and then n-hexane and dichloromethane solutions were added in a ratio of 1:1:1 to mix, and then the precipitate was taken after centrifugation at 10000 rpm / min for 10 min, and isopropanol solution was added to the precipitate, and then centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and then isopropanol solution was added to mix, and then centrifuged at 10000 rpm / min for 10 min, and the precipitate was taken, and finally 2 mL of isopropanol solution was added and centrifuged at 1000 rpm / min for 10 min, and the supernatant was taken, and finally WSe2 nanosheets of appropriate size were obtained, which were dispersed in isopropanol solution to obtain two-dimensional semiconductor WSe2 ink.

[0089] 2. Irradiate the clean Si / SiO2 substrate under UV light for 15 minutes, and spin-coat the prepared two-dimensional semiconductor WSe2 ink on the clean Si / SiO2 substrate. The spin coating method is static spin coating, the rotation speed is 1500rpm / min, the spin coating time is 20s, and the number of spin coatings is 8 times. After the spin coating is completed, anneal it on a heating table at 200℃ for 15 minutes, and finally form a WSe2 van der Waals film of about 40nm;

[0090] 3. Prepare an isopropanol solution of 100 mM phenylselenol, soak the formed WSe2 van der Waals film in the prepared phenylselenol solution for 32 hours, rinse with isopropanol solution, and after the solution evaporates slowly, anneal at a high temperature of 210°C for 30 minutes to finally prepare a WSe2 van der Waals film treated with phenylselenol.

[0091] 4. A metal electrode was deposited on the surface of the WSe2 van der Waals film obtained above to complete the preparation of the field effect transistor. The thickness of the deposited gold film was 50 nm and the deposition rate was

[0092] like Figure 3 As shown, there are AFM images of the original WSe2 van der Waals film and the WSe2 van der Waals film modified with phenylselenol. After modification, the surface roughness of the film is reduced from 14.79nm to 11.88nm, indicating that in the present invention, the quality of the WSe2 van der Waals film modified with phenylselenol is greatly improved.

[0093] like Figure 4 The figure shows the transfer characteristic curves of field effect transistors based on the original and phenylselenol-modified WSe2 van der Waals films. The horizontal axis is V Gs represents the applied gate-source voltage, and the vertical axis is I DS It represents the absolute value of the measured drain-source current. It can be seen from the figure that the carrier mobility and current switching ratio of the device after the WSe2 van der Waals film of the semiconductor channel layer is modified by phenylselenol are significantly improved.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A field effect transistor based on phenylselenol modified WSe2 van der Waals film, characterized in that: The WSe2 van der Waals film modified with phenylselenol is used as the semiconductor channel of the field effect transistor.

2. A field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 1, characterized in that: The invention comprises a gate layer (1), an insulating layer (2), a semiconductor channel layer (3) and an electrode layer (4) which are arranged in sequence; the semiconductor channel layer (3) adopts a WSe2 van der Waals film modified with phenylselenol, and the electrode layer (4) comprises a source electrode (5) and a drain electrode (6) which are respectively arranged on both sides of the semiconductor channel layer (3).

3. A field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 2, characterized in that: The gate layer (1) is made of silicon, the insulating layer (2) is made of silicon dioxide, and the source electrode (5) and the drain electrode (6) are made of gold.

4. A field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 1, characterized in that: The thickness of the semiconductor channel layer (3) is 20-60 nm.

5. The method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 1, characterized in that: The following steps are involved: Step 1, irradiate a clean silicon / silicon dioxide substrate under ultraviolet light for 10 to 20 minutes, and then spin-coat the two-dimensional semiconductor WSe2 ink prepared by intercalation reaction in a double-electrode electrochemical cell on the clean silicon / silicon dioxide substrate. The spin coating method is static spin coating. After the spin coating is completed, annealing is performed on a heating table to finally form a WSe2 van der Waals film; Step 2, preparing an isopropanol solution of phenylselenol with a concentration of 10 to 150 mM; Step 3, immersing the device obtained in step 1 in the phenylselenol solution prepared in step 2, and after immersion, rinsing the device with an isopropanol solution, and after the solution evaporates slowly, annealing is performed to finally prepare a WSe2 van der Waals film treated with phenylselenol; Step 4: evaporate a metal electrode on the surface of the WSe2 van der Waals film to form a source electrode (5) and a drain electrode (6), thereby completing the preparation of the field effect transistor.

6. The method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 5, characterized in that: In step 1, the preparation method of the two-dimensional semiconductor WSe2 ink is: Step 1.1, using two-dimensional semiconductor WSe2 as cathode, graphite rod as anode, a mixed solution of 0.2-0.3g tetraheptylammonium bromide and 40mL acetonitrile as electrolyte, the applied voltage is set to 25V, and the intercalation process is carried out for 3-5h; Step 1.2, repeatedly washing the material obtained in step 1 with an ethanol solution to remove electrolytes, blowing the washed material dry and dispersing it in an 8 mg / mL polyvinyl pyrrolidone / nitromethyl pyrrolidone solution, and then performing ultrasonic stripping treatment in a plasma cleaning machine with a power of 100 W for 5 to 10 minutes; Step 1.3, centrifuge the solution after ultrasound, first centrifuge at 1000 rpm / min for 10-15 minutes, then take the supernatant, then add n-hexane and dichloromethane solutions in a ratio of 1:1:1 to mix to obtain a mixed solution, centrifuge the mixed solution at 10000 rpm / min for 10 minutes to obtain a precipitate, add isopropanol solution to the precipitate, and then centrifuge at 1000 rpm / min for 10 minutes to obtain the supernatant, add isopropanol solution to the supernatant again to mix, centrifuge at 10000 rpm / min for 10 minutes to obtain the precipitate, finally add isopropanol solution to the precipitate and centrifuge at 1000 rpm / min for 10 minutes to obtain the supernatant, and finally obtain WSe2 nanosheets of appropriate size dispersed in the isopropanol solution, which is the obtained two-dimensional semiconductor WSe2 ink.

7. The method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 6, characterized in that: In the step 1.3, the steps of adding isopropanol solution to the supernatant to mix, centrifuging at a speed of 10000 rpm / min for 10 min and taking the precipitate, and finally adding isopropanol solution to the precipitate and centrifuging at 1000 rpm / min for 10 min and taking the supernatant are repeated 1 to 2 times, each time adding 1-3 mL of isopropanol solution.

8. The method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 5, characterized in that: In the step 1, the spin coating speed is 1500 rpm / min, the spin coating time is 20 s, and the number of spin coatings is 5 to 14 times; after the spin coating is completed, annealing is performed on a heating table at 200° C. for 15 minutes to finally form a WSe2 van der Waals film with a thickness of 20 to 60 nm.

9. The method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 5, characterized in that: In step 3, the soaking time is 24 to 36 hours; the annealing temperature is 80 to 210° C., and the annealing time is 30 minutes.

10. The method for preparing a field effect transistor based on phenylselenol modified WSe2 van der Waals thin film according to claim 5, characterized in that: In the step 4, the thickness of the evaporated metal electrode is 50-100 nm.

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