A SiC nanowire network functional thin film, its preparation method and application

Abstract

The present invention belongs to the technical field of semiconductor nanowire material preparation, and discloses a SiC nanowire network functional thin film, a preparation method and an application thereof. The preparation method is as follows: SiC nanowires are used to form a suspension of SiC nanowires with solvent A under the action of a dispersant and a conductive solute; the suspension of SiC nanowires is used as an electrophoretic deposition solution, and a substrate is used as the cathode. A SiC nanowire thin film A is deposited on the substrate through electrophoretic deposition treatment; a plasma jet is used to perform welding treatment on the SiC nanowire thin film A to obtain a SiC nanowire thin film B. The method of the present invention is simple, low-cost, high-efficiency and safe and easy to operate, has a certain universality for low-dimensional nanostructures, can prepare thin films on different substrates under room temperature conditions, and the prepared SiC nanowire thin film is uniform and dense, and can be used for preparing SiC nano-optical devices.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor nanowire material preparation, and particularly relates to a SiC nanowire network functional thin film, a preparation method thereof, and an application thereof. Background Art

[0002] In addition to the characteristics of high thermal conductivity, strong thermal stability, oxidation resistance, chemical corrosion resistance, low thermal expansion coefficient, high thermal conductivity, good chemical stability, and high mechanical properties of silicon carbide (SiC) itself, one-dimensional nanoscale silicon carbide (SiC) also has a high bandgap width, a small dielectric constant, a relatively high electron saturation mobility, a high critical breakdown electric field, a high thermal conductivity, and many other excellent characteristics, and is expected to prepare micro-nano devices with better performance.

[0003] Those skilled in the art have found that thin film materials assembled from one-dimensional nanomaterials such as nanowires and nanotubes into two-dimensional macroscopically visible ones have the characteristics of both one-dimensional and two-dimensional nanomaterials and have extremely extensive and potential application values in many fields. Therefore, this material, especially the silicon carbide nanowire thin film material, has attracted much attention from those skilled in the art.

[0004] In the prior art, SiC nanowires are mainly grown on substrates such as crucibles, ceramic substrates, and graphite papers. However, the inventor has found that the nanowires prepared by the above methods are mostly independent nanowire monomers growing randomly on the substrate, and the nanowire thin film assembled from randomly grown nanowires has a low density and many pores, and it is very difficult to separate from the substrate (it will become powder after separation), which severely limits the application and development of the nanowire thin film. At the same time, the raw material cost of the above preparation method of the nanowire thin film is high, the experimental process is cumbersome, the cycle is long, the energy consumption is large, and the SiC nanomaterials prepared in a single furnace are small, which is not conducive to the large-scale production and further development of the nanowire thin film.

[0005] Therefore, the present invention provides a SiC nanowire network functional thin film, a preparation method thereof, and an application thereof. Summary of the Invention

[0006] In order to solve the above deficiencies in the prior art, the present invention provides a SiC nanowire network functional thin film, a preparation method thereof, and an application thereof.

[0007] The SiC nanowire network functional thin film, the preparation method thereof, and the application thereof of the present invention are realized through the following technical solutions:

[0008] The first object of the present invention is to provide a preparation method of a SiC nanowire network functional thin film, including the following steps:

[0009] Step 1, uniformly disperse silicon carbide nanowires in solvent A under the action of a dispersant and a conductive solute to obtain a suspension of silicon carbide nanowires;

[0010] Step 2: Using the obtained suspension of silicon carbide nanowires as the electrophoretic deposition solution, with the substrate as the cathode, perform electrophoretic deposition treatment at room temperature to deposit a uniform and dense silicon carbide nanowire thin film A on the substrate.

[0011] Step 3: Use room-temperature atmospheric-pressure plasma jet to weld the silicon carbide nanowire thin film A, weld the intersecting nanowires on the silicon carbide nanowire thin film A, and obtain a silicon carbide nanowire thin film B.

[0012] Furthermore, the process of the welding treatment is as follows:

[0013] Place the silicon carbide nanowire thin film A under the room-temperature atmospheric-pressure plasma jet, move the silicon carbide nanowire thin film at a rate of 5 - 20 mm / s in a two-dimensional plane, and weld for 10 - 40 minutes until the silicon carbide nanowires are connected in many irregular crosslinks, realizing the nano-welding of the intersections on a larger area of the silicon carbide nanowire thin film.

[0014] Furthermore, the content of silicon carbide nanowires in the suspension of silicon carbide nanowires is 0.05 - 0.1 g / 100 mL;

[0015] The diameter of the silicon carbide nanowires is 50 - 500 nm, and the length is 50 - 100 μm.

[0016] Furthermore, the dispersant is any one of sodium dodecylbenzenesulfonate, sodium tripolyphosphate, sodium dodecyl sulfate, and polyacrylamide;

[0017] The conductive solute is any one of aluminum nitrate, sodium chloride, ammonium chloride, and potassium nitrate;

[0018] The solvent A is one or both of isopropyl alcohol and ethylene glycol.

[0019] Furthermore, the mass ratio of the dispersant to the silicon carbide nanowires is 1:1 - 2;

[0020] The mass ratio of the conductive solute to the silicon carbide nanowires is 1:0.01 - 0.1.

[0021] Furthermore, the anode used in the electrophoretic deposition treatment is a platinum sheet, the distance between the electrodes is 0.5 - 2 cm, and a constant voltage of 50 - 100 V is applied;

[0022] And during the electrophoretic deposition treatment, the suspension of silicon carbide nanowires is maintained in a homogeneous component state.

[0023] Furthermore, the silicon carbide nanowire film B is also subjected to high-temperature bonding treatment, so that the nanowires are tightly connected under the action of high temperature and pressure, and a silicon carbide nanowire film C with cross-linked nanowires is obtained, that is, the SiC nanowire network functional film is obtained;

[0024] And the process of the high-temperature bonding is as follows:

[0025] At a temperature of 500-1000 °C, the surface of the silicon carbide nanowire film B is treated with NH3 plasma for 5-60 min, and then under argon protection, it is isothermally bonded at a temperature of 1000-1200 °C for 30-60 min.

[0026] The second object of the present invention is to provide a SiC nanowire network functional film prepared by the above preparation method.

[0027] The third object of the present invention is to provide an application of the above SiC nanowire network functional film in the preparation of SiC nano-optoelectronic devices.

[0028] Furthermore, before being used for the preparation of SiC nano-optoelectronic devices, it also undergoes the following treatment:

[0029] By using the thermal electron beam evaporation method, an ordered metal electrode array is evaporated on the silicon carbide nanowire film B or the silicon carbide nanowire film C, followed by annealing treatment. Then, physical peeling is carried out using a PVA glue solution to obtain a silicon carbide nanowire film D, and the silicon carbide nanowire film D is transferred to a new substrate for the preparation of SiC nano-optoelectronic devices.

[0030] Furthermore, the single-crystal silicon carbide nanowires are obtained through the following steps:

[0031] After the silicon carbide aerogel is cleaned, it is immersed in an acid solution and subjected to ultraviolet ultrasonic treatment I. Then, it is left to stand until the solution is stratified, the supernatant is poured out, an aqueous solvent is added to the remaining solution, and ultraviolet ultrasonic treatment II is carried out again. After standing, the supernatant is poured out, and the above steps are repeated at least 3 times. The solution part from which the supernatant has been removed is subjected to solid-liquid separation, and after the obtained solid-phase component is dried, it is the single-crystal silicon carbide nanowires.

[0032] Furthermore, the acid solution is a 98% hydrofluoric acid solution or an 85% hot concentrated phosphoric acid, which removes the silicon dioxide layer on the surface of the silicon carbide aerogel, and the dosage ratio of the silicon carbide aerogel to the acid solution is 1 g: 20-100 mL.

[0033] Furthermore, the added amount of the aqueous solution is equal to the volume of the poured-out supernatant.

[0034] Further, the processes of each of the ultraviolet ultrasonic treatment I and the ultraviolet ultrasonic treatment II are as follows: the ultrasonic power is 150 W, the ultrasonic time is 2 - 3 h, and the ultrasonic temperature is 30 - 50 °C; the wavelength of the ultraviolet light is 365 nm, and the power is 5 - 10 W;

[0035] Further, when preparing the single-crystal silicon carbide nanowires, the solid-phase component is also subjected to a washing treatment before the drying treatment, and the washing treatment is to wash the solid-phase component with an aqueous solvent until the washing liquid is neutral (pH = 7).

[0036] Further, the silicon carbide aerogel is prepared by a carbothermal reduction method.

[0037] Further, before the substrate is subjected to electrophoretic deposition, it also undergoes the following pretreatment:

[0038] The substrate is ultrasonically cleaned in acetone, absolute ethanol, and deionized water for 15 - 20 min respectively, taken out and dried in an oven at 60 - 80 °C for 10 - 20 min.

[0039] The second object of the present invention is to provide an SiC nanowire network functional thin film prepared by the above preparation method.

[0040] The third object of the present invention is to provide an application of the above SiC nanowire network functional thin film in the preparation of SiC nano-optical devices.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The preparation raw materials of the present invention have low cost, simple and convenient operation, and easy growth control; at the same time, the preparation temperature is relatively low, which can avoid the phase change and brittle fracture of the material in a high-temperature environment, is easy to achieve a uniform distribution of the microstructure of the material, and the deposited thin film has self-supporting properties, which is convenient for peeling and transferring.

[0043] The present invention provides an effective bottom-up assembly nanostructure method for preparing silicon carbide nanowire thin films, with simple process, high efficiency and safe and easy operation. In the present invention, with the substrate as the cathode and the platinum sheet as the anode, they are immersed in a liquid medium containing the silicon carbide nanowire suspension, a direct current or alternating current is applied, and the solution is stirred with a magnetic stirrer, thereby forming an electric field therebetween, wherein the silicon carbide nanowires migrate to the surface of the substrate and deposit thereon. The uniform and large-area preparation of the silicon carbide nanowire thin film is realized. The thin film can be prepared on various substrates such as metals, non-conductive, semiconductors (rigid / flexible, conductive / non-conductive) at room temperature, and has universality for the preparation of low-dimensional nanostructures.

[0044] The prepared silicon carbide nanowire film of the present invention has a certain self-supporting property. By spin-coating an aqueous solution of polyvinyl alcohol on the film surface, after the polyvinyl alcohol is dried, the film can be directly and completely peeled off and transferred to the target substrate by a physical method. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a physical picture of the silicon carbide nanowire aerogel prepared by the present invention;

[0046] Figure 2 It is a physical picture of the silicon carbide nanowire film B prepared in Example 1 of the present invention;

[0047] Figure 3 It is an XRD pattern of the silicon carbide nanowire aerogel prepared by the present invention;

[0048] Figure 4 It is an SEM picture of the silicon carbide nanowire film A in Example 1 of the present invention;

[0049] Figure 5 It is an SEM picture of the silicon carbide nanowire film B in Example 1 of the present invention;

[0050] Figure 6 It is a schematic structural diagram of the SiC nano-optoelectronic device prepared in Example 11 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] As described in the background art section, there are still many problems in the prior art in preparing high-quality and large-size silicon carbide nanowire network films. Therefore, there is an urgent need to develop a general, large-size, high-efficiency, and low-cost method, especially an urgent need for a preparation method of a silicon carbide nanowire network film that can be applied to SiC nano-optoelectronic devices. For this purpose, the present invention provides a SiC nanowire network functional film, its preparation method, and application. And the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0052] Example 1

[0053] This example provides a SiC nanowire network functional film, and its preparation method is as follows:

[0054] Step 1, under the action of a dispersant and a conductive solute, uniformly disperse silicon carbide nanowires in solvent A to obtain a suspension of silicon carbide nanowires;

[0055] The present invention does not limit the specific composition of solvent A, as long as it can achieve the dispersion of the silicon carbide nanowire aerogel in the solvent. Optionally, in this example, isopropyl alcohol is used as solvent A, and 100 mL of isopropyl alcohol is measured and reserved;

[0056] The present invention does not limit the specific components of the dispersant, as long as it can promote the uniform dispersion of the silicon carbide nanowire aerogel in solvent A. Optionally, in this embodiment, sodium dodecylbenzenesulfonate is used as the dispersant, and 0.075 g of sodium dodecylbenzenesulfonate is weighed and reserved.

[0057] The present invention does not limit the specific components of the conductive solute, as long as it can achieve the directional movement of silicon carbide nanowires in an electrostatic field. Optionally, in this embodiment, aluminum nitrate is used as the conductive solute, and 0.0025 g of aluminum nitrate is weighed and reserved.

[0058] The present invention does not limit the specific dispersion treatment method of silicon carbide nanowires in solvent A, as long as a uniform suspension of silicon carbide nanowires can be obtained. Optionally, in this embodiment, ultrasonic dispersion is used. After adding the weighed 0.075 g of sodium dodecylbenzenesulfonate, 0.0025 g of aluminum nitrate and 0.05 g of silicon carbide nanowires to 100 mL of isopropanol, ultrasonic treatment is carried out at an ultrasonic power of 150 W for 30 - 50 min to enable the directional movement of the nanowires in the electrostatic field and form a stable suspension, thereby obtaining a silicon carbide nanowire suspension.

[0059] Step 2: Using the obtained silicon carbide nanowire suspension as the electrophoretic deposition solution, with the substrate as the cathode, electrophoretic deposition treatment is carried out at room temperature to deposit a uniform and dense silicon carbide nanowire film A on the substrate;

[0060] It should be noted that the present invention does not limit the type and specific size of the substrate, which can be selected according to actual needs. For example, if a flexible device is to be prepared, a copper foil, PET, graphite paper, carbon cloth or other flexible devices can be selected; if a heterojunction device is to be prepared, a p-type or n-type doped substrate can be used. Optionally, in this embodiment, a copper foil substrate is used, and the thickness of the copper foil substrate is 0.05 mm and it is double-sided conductive. Before the electrophoretic deposition treatment, the copper foil substrate also undergoes the following pretreatment: first, it is preliminarily cleaned with deionized water, and then ultrasonically cleaned in acetone, absolute ethanol, and deionized water for 15 - 20 min in sequence, and then taken out and dried in an oven at 60 - 80 °C for 10 - 20 min.

[0061] The present invention does not limit the specific process parameters of the electrophoretic deposition treatment and the substrate size, as long as a uniform and dense silicon carbide nanowire thin film A can be deposited on the copper foil substrate. In this embodiment, optionally, at room temperature, a platinum sheet is used as the anode, and it is immersed together with the pre-treated copper foil substrate in the suspension of silicon carbide nanowires prepared in the above step 1. The electrode spacing is 0.5 - 2 cm. A DC power supply is used as the electrophoretic apparatus, and a constant voltage of 50 - 100 V is applied. During the deposition process, a magnetic stirrer is used to stir the solution at a rate of 80 - 120 r / min, so that the suspension of silicon carbide nanowires always remains homogeneous during the deposition process. Electrophoretic deposition is carried out for 6 - 15 min to obtain a silicon carbide nanowire thin film A with uniform and dense deposition.

[0062] Step 3, use room temperature and atmospheric pressure plasma jet to weld the silicon carbide nanowire thin film A, and weld the intersecting nanowires on the silicon carbide nanowire thin film A to obtain a silicon carbide nanowire thin film B;

[0063] It should be noted that the present invention does not limit the specific method and specific parameters of the welding treatment, as long as the intersecting nanowires on the silicon carbide nanowire thin film A are welded to form a silicon carbide nanowire network thin film with a larger area. And those skilled in the art should know that the room temperature and atmospheric pressure plasma jet described in the present invention is a new atmospheric pressure glow discharge cold plasma source, which can generate a plasma jet with a temperature between 25 - 40 °C and a high active particle concentration under atmospheric pressure, and there are N2, Ar, OH, and carbon substances in the plasma jet. Optionally, the following process is used for welding treatment in this embodiment:

[0064] Place the silicon carbide nanowire thin film A under the room temperature and atmospheric pressure plasma jet, use a pulse power supply with a power value of 8 kv and a frequency of 26 kHz, and move the silicon carbide nanowire thin film at a rate of 5 - 20 mm / s in a two-dimensional plane, so that the room temperature and atmospheric pressure plasma jet welds the silicon carbide nanowires on the silicon carbide nanowire thin film. The welding treatment is carried out for 10 - 40 min until the silicon carbide nanowires are connected in many irregular crosslinks to achieve nano-welding of the cross points on the silicon carbide nanowire thin film with a larger area.

[0065] Example 2

[0066] This embodiment provides a SiC nanowire network functional thin film, and the difference between the preparation method of the 3C-SiC nanowire functional composite network thin film in this embodiment and that in Example 1 is only that:

[0067] In step 1 of this embodiment, sodium tripolyphosphate is used as the dispersant, aluminum nitrate is used as the conductive solute, and ethylene glycol is used as solvent A;

[0068] In step 2 of this embodiment, the electrode spacing for electrophoretic deposition treatment is 0.5 cm. A DC power supply is used as the electrophoretic apparatus, and a constant voltage of 50 V is applied. During the deposition process, a magnetic stirrer is used to stir the solution at a rate of 80 r / min to keep the suspension of silicon carbide nanowires homogeneous in composition throughout the deposition process. Electrophoretic deposition is carried out for 15 min to obtain a silicon carbide nanowire thin film A with uniform and dense deposition.

[0069] In step 3 of this embodiment, during the welding treatment, the silicon carbide nanowire thin film is moved at a rate of 5 mm / s in a two-dimensional plane, and the welding treatment is carried out for 40 min until the silicon carbide nanowires are connected in many irregular crosslinks to achieve nano-welding of the cross points on a larger area of the silicon carbide nanowire thin film.

[0070] Example 3

[0071] This embodiment provides a SiC nanowire network functional thin film. The difference between the preparation method of the 3C-SiC nanowire functional composite network thin film in this Example 3 and that in Example 1 is only as follows:

[0072] In step 1 of this embodiment, sodium dodecyl sulfate is used as the dispersant, potassium nitrate is used as the conductive solute, and ethylene glycol is used as solvent A;

[0073] In step 2 of this embodiment, the electrode spacing for electrophoretic deposition treatment is 2 cm. A DC power supply is used as the electrophoretic apparatus, and a constant voltage of 100 V is applied. During the deposition process, a magnetic stirrer is used to stir the solution at a rate of 120 r / min to keep the suspension of silicon carbide nanowires homogeneous in composition throughout the deposition process. Electrophoretic deposition is carried out for 6 min to obtain a silicon carbide nanowire thin film A with uniform and dense deposition.

[0074] In step 3 of this embodiment, during the welding treatment, the silicon carbide nanowire thin film is moved at a rate of 20 mm / s in a two-dimensional plane, and the welding treatment is carried out for 10 min until the silicon carbide nanowires are connected in many irregular crosslinks to achieve nano-welding of the cross points on a larger area of the silicon carbide nanowire thin film.

[0075] Example 4

[0076] This embodiment provides a SiC nanowire network functional thin film. The difference between the preparation method of the 3C-SiC nanowire functional composite network thin film in this Example 4 and that in Example 1 is only as follows:

[0077] The amount of the silicon carbide nanowires used is 0.1 g, and the mass ratio of the dispersant to the silicon carbide nanowires is 1:1; the mass ratio of the conductive solute to the silicon carbide nanowires is 1:0.01.

[0078] Example 5

[0079] This embodiment provides a SiC nanowire network functional thin film, and the difference between the preparation method of the 3C-SiC nanowire functional composite network thin film in this embodiment and that in Embodiment 1 is only that:

[0080] The dosage of the silicon carbide nanowires is 0.1 g, and the mass ratio of the dispersant to the silicon carbide nanowires is 1:2;

[0081] The mass ratio of the conductive solute to the silicon carbide nanowires is 1:0.1.

[0082] Embodiment 6

[0083] This embodiment provides a SiC nanowire network functional thin film, and the difference between the preparation method of the 3C-SiC nanowire functional composite network thin film in this embodiment and that in Embodiment 1 is only that:

[0084] In this embodiment, graphite paper is used as the substrate, and the thickness of the graphite paper substrate is 0.3 mm, and it is conductive on both sides.

[0085] Embodiment 7

[0086] This embodiment provides a SiC nanowire network functional thin film, and the difference between the preparation method of the 3C-SiC nanowire functional composite network thin film in this embodiment and that in Embodiment 1 is only that:

[0087] In this embodiment, a silicon substrate is used as the substrate, and the thickness of the silicon substrate is 500 ± 25 μm, and the resistivity < 0.009 Ω / cm.

[0088] Embodiment 8

[0089] This embodiment provides a SiC nanowire network functional thin film, and the difference between the preparation method of the 3C-SiC nanowire functional composite network thin film in this embodiment and that in Embodiment 1 is only that:

[0090] In this embodiment, ITO is used as the substrate, and the thickness of the ITO substrate is 2 mm, and the resistance value is 3 - 4 Ω.

[0091] Embodiment 9

[0092] This embodiment provides a SiC nanowire network functional thin film, and the difference between the preparation method of the 3C-SiC nanowire functional composite network thin film in this embodiment and that in Embodiment 1 is only that:

[0093] In this embodiment, PET is used as the substrate, and the thickness of the PET substrate is 0.05 mm, and it is conductive on one side.

[0094] Embodiment 10

[0095] This embodiment provides a SiC nanowire network functional thin film. In this embodiment, the silicon carbide nanowire thin film B prepared in any one of Embodiments 1 - 9 is subjected to a high-temperature bonding treatment to obtain a silicon carbide nanowire thin film C, which is the SiC nanowire network functional thin film of this embodiment.

[0096] It should be noted that the present invention does not limit the specific process of the high-temperature bonding treatment, as long as it can enhance the surface bonding of the silicon carbide nanowire network thin film. Optionally, in this embodiment, the following process is adopted: at a temperature of 500 - 1000 °C, the surface of the silicon carbide nanowire thin film B is treated with NH3 plasma for 5 - 60 min, and then under argon protection, it is isothermally bonded at a temperature of 1000 - 1200 °C for 30 - 60 min.

[0097] Embodiment 11

[0098] This embodiment provides a SiC nano-optoelectronic device, and the preparation method is as follows:

[0099] Using the thermal electron beam evaporation method, an ordered metal electrode array is evaporated on the silicon carbide nanowire thin film B prepared in any one of Embodiments 1 - 9, or the silicon carbide nanowire thin film C prepared in Embodiment 10, followed by annealing treatment. Subsequently, physical peeling is carried out using a PVA glue solution to obtain a silicon carbide nanowire thin film D, and the silicon carbide nanowire thin film D is used to prepare a SiC nano-optoelectronic device.

[0100] It should be noted that the present invention does not limit the specific operation of the above thermal electron beam evaporation method and the composition of the specific metal electrode, and corresponding selections can be made according to actual needs, as long as an ordered metal electrode array can be evaporated on the silicon carbide nanowire thin film B or the silicon carbide nanowire thin film C. In this embodiment, optionally, taking nickel metal material as an example, the following steps are used to evaporate an ordered nickel electrode array on the surface of the peeled thin film: the evaporation time is 5 - 20 min, the distance between adjacent two electrodes is 40 - 200 μm, and the electrode thickness is 100 - 300 nm.

[0101] The present invention does not limit the specific process of annealing the thin film with the evaporated metal electrode, as long as it can remove the residual water molecules and solvents in the thin film at high temperature and strengthen the contact between the thin film and the electrode. In this embodiment, optionally, the following process is adopted: the thin film with the evaporated electrode is put into a vacuum annealing furnace for annealing, the annealing temperature is 800 - 1000 °C, the heating rate is 10 - 60 °C / min, and the annealing time is 60 - 200 min.

[0102] The present invention does not limit the specific operation process of physical peeling using a polyvinyl alcohol (PVA) glue solution as described above, as long as the peeling of the thin film can be achieved. In this embodiment, optionally, the following process is adopted: Place the annealed thin film coated with nickel electrodes in a spin coater with a rotation speed of 500 - 900 rpm, and uniformly coat 3 - 6 drops of polyvinyl alcohol (PVA) glue solution on the surface of the thin film, with each drop being 20 - 100 μL. After drying, physically peel the thin film, and finally wash the surface of the thin film with deionized water to remove the PVA film.

[0103] It should be noted that the present invention does not limit the specific preparation method of silicon carbide nanowires in the above embodiments, as long as clean silicon carbide nanowires can be obtained. Optionally, the single-crystalline silicon carbide nanowires are obtained through the following steps:

[0104] Wash the silicon carbide aerogel, immerse it in an acid solution, and perform ultraviolet ultrasonic treatment. Then, let it stand until the solution is layered, pour out the supernatant, add a water solvent to the remaining solution, perform ultraviolet ultrasonic treatment again, let it stand again, and then pour out the supernatant. Repeat the above steps at least 3 times. Separate the solid-liquid of the solution part after removing the supernatant. After drying the obtained solid-phase component, it is the single-crystalline silicon carbide nanowire;

[0105] It should be noted that the present invention does not limit the specific composition and dosage of the acid solution, as long as the silicon dioxide layer on the surface of the silicon carbide aerogel can be removed. Optionally, the present invention uses a 98% hydrofluoric acid solution or an 85% hot concentrated phosphoric acid solution as the acid solution, and weighs 100 - 500 mL of the 98% hydrofluoric acid solution or 85% hot concentrated phosphoric acid for standby.

[0106] The present invention does not limit the specific process of the above ultraviolet ultrasonic treatment, as long as it can dissolve the silicon carbide aerogel to prepare a silicon carbide aerogel suspension with uniform concentration. Optionally, the present invention is implemented by the following process: Immerse 5 g of silicon carbide aerogel in 100 - 500 mL of the above-mentioned weighed 98% hydrofluoric acid solution or 85% hot concentrated phosphoric acid, under the irradiation of an ultraviolet lamp with a wavelength of 365 nm and a light power of 5 - 10 W, at a temperature of 30 - 50 °C, ultrasonically treat with an ultrasonic power of 150 W for 0.5 - 3 h, then let it stand for 30 - 500 min, pour out the supernatant (90 - 450 mL), and the remaining solution is solution A; then add a certain amount of deionized water (90 - 450 mL) to solution A, and then perform ultraviolet light ultrasonic dispersion treatment and separation. After repeating the above steps 5 - 8 times, then put solution A into a centrifuge tube to obtain SiC nanowires by centrifugation, then disperse them into deionized water, and then perform centrifugation treatment. Repeat the above operation until the solution pH is 7 to obtain single-crystalline silicon carbide nanowires without impurities, monodispersed, with a crystal phase of 3C phase, a density of 3.21 g / cc, a uniform size distribution, a diameter of 50 - 300 nm, and a length of 10 - 100 μm. Dry (such as drying treatment in a vacuum drying oven at 60 °C for 4 h) for standby.

[0107] The present invention does not limit the specific operation of the cleaning treatment of the silicon carbide aerogel, as long as it can remove the impurities in the silicon carbide aerogel. Optionally, the present invention is implemented by the following process: Immerse the silicon carbide aerogel in acetone, absolute ethanol, and deionized water respectively and ultrasonically clean for 10 - 20 min.

[0108] The present invention does not limit the specific preparation method of the silicon carbide aerogel, as long as a clean silicon carbide aerogel can be obtained. Optionally, the present invention prepares the silicon carbide aerogel by the following steps:

[0109] Dissolve polycarbosilane and vinyl compound in solvent B, under anaerobic conditions at 70 - 90 °C, catalyze the reaction with Karstedt catalyst for 4 - 8 h to obtain polycarbosilane gel; dry the polycarbosilane gel and then perform heat treatment to obtain a silicon carbide / carbon precursor aerogel, then add rice husk carbon and silicon and mix evenly, and then calcine in an anaerobic argon atmosphere at 1000 - 1800 °C for 0.5 - 5 h to obtain silicon carbide aerogel, and the physical diagram of the obtained silicon carbide aerogel is as Figure 1 shown;

[0110] Among them, when preparing the silicon carbide aerogel, the vinyl compound contains two or more vinyl groups;

[0111] The solvent B is one or more of cyclohexane, toluene, xylene, or benzene;

[0112] The polycarbosilane and the vinyl compound are mixed in any proportion, and the ratio of the total mass of the polycarbosilane and the vinyl compound to the amount of the solvent B is 0.03 - 0.3 g:1 mL;

[0113] The drying is supercritical drying or freeze drying;

[0114] The dosage ratio of the silicon carbide / carbon precursor aerogel, rice husk carbon, and silicon is 1 - 0.5:0.8:0.1 - 0.3;

[0115] The rice husk carbon is commercialized with a particle size of less than 200 mesh and a purity of 99%.

[0116] Experimental section

[0117] (I) Physical morphology

[0118] In the present invention, the physical pictures of the silicon carbide aerogel prepared by the present invention and the silicon carbide nanowire films prepared in Examples 1 and 6 - 9 were taken respectively, as shown in Figure 1 and Figure 2 respectively.

[0119] Figure 1 is the physical picture of the silicon carbide aerogel prepared by the present invention. It can be seen that the silicon carbide aerogel prepared by the present invention has an extremely light mass and can be placed on a dandelion, and has an ultra - low density, about 0.0382 g / cm 3 .

[0120] Figure 2 (from left to right in sequence) are the physical pictures of the silicon carbide nanowire films prepared in Example 8, Example 6, Example 9, Example 1, and Example 7 of the present invention. It can be seen that the silicon carbide nanowire films prepared by the present invention (the part framed by the black line drawing) are uniform and dense.

[0121] (II) XRD test

[0122] In the present invention, the XRD test was carried out on the silicon carbide aerogel prepared by the present invention, and the test results are as shown in Figure 3 respectively.

[0123] From Figure 3 as shown, it can be seen that the 3C - phase SiC nanowire aerogel prepared by the present invention.

[0124] (III) SEM test

[0125] In the present invention, the SEM tests were carried out on the silicon carbide nanowire film A at different stages during the preparation process of the silicon carbide nanowire film in Example 1 and the silicon carbide nanowire film B after welding treatment respectively, and the test results are as shown in Figure 4 and Figure 5 respectively.

[0126] From Figure 4 and Figure 5 as shown, it can be seen that: the average length of a single nanowire can reach more than 100 μm, and it has good flexibility. The long silicon carbide nanowires as channels are more conducive to the preparation of high-performance thin films with better bonding, lower contact resistance and higher crosslinking degree of the nanowire network. The nanowire crosslinking network formed by welding can densify the silicon carbide aerogel-derived film, which is beneficial to the development of high-stability, high-performance and flexible optoelectronic devices.

[0127] Figure 6 This is a schematic structural diagram of the SiC nano-optoelectronic device prepared from the silicon carbide nanowire thin film B prepared in Example 7 in Example 11 of the present invention. It can be seen that the silicon carbide nanowire thin film is deposited on the silicon-based substrate, and nickel electrodes with a spacing of 40 μm are prepared by using the thermal electron beam evaporation technique. After annealing, the Si / 3C-SiC nano-optoelectronic device is prepared, and the detection test of ultraviolet light with a wavelength of 200 nm to 400 nm is carried out.

[0128] Obviously, the above embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

Claims

1. A preparation method of a SiC nanowire network functional thin film, characterized in that, It includes the following steps: Step 1: Under the action of a dispersant and a conductive solute, uniformly disperse silicon carbide nanowires in solvent A to obtain a suspension of silicon carbide nanowires; Step 2: Use the obtained suspension of silicon carbide nanowires as the electrophoretic deposition solution, use the substrate as the cathode, and perform electrophoretic deposition treatment at room temperature to deposit a uniform and dense silicon carbide nanowire thin film A on the substrate; Step 3: Use room-temperature atmospheric-pressure plasma jet to weld the silicon carbide nanowire thin film A, and weld the intersecting nanowires on the silicon carbide nanowire thin film A to obtain a silicon carbide nanowire thin film B; The process of the welding treatment is as follows: Place the silicon carbide nanowire thin film A under the room-temperature atmospheric-pressure plasma jet, move the silicon carbide nanowire thin film at a rate of 5-20 mm / s in a two-dimensional plane, and weld until the silicon carbide nanowires are connected in many irregular crosslinks; Perform high-temperature bonding treatment on the silicon carbide nanowire thin film B to obtain a silicon carbide nanowire thin film C with crosslinked nanowires, that is, obtain the SiC nanowire network functional thin film; And the process of the high-temperature bonding is: At a temperature of 500-1000 °C, use NH3 plasma to treat the surface of the silicon carbide nanowire thin film B for 5-60 min, and then under argon protection, perform isothermal bonding at a temperature of 1000-1200 °C for 30-60 min.

2. The preparation method according to claim 1, characterized in that, The content of silicon carbide nanowires in the suspension of silicon carbide nanowires is 0.05-0.1 g / 100 mL; The diameter of the silicon carbide nanowires is 50-500 nm, and the length is 50-100 μm.

3. The preparation method according to claim 1, characterized in that, The dispersant is any one of sodium dodecylbenzenesulfonate, sodium tripolyphosphate, sodium dodecyl sulfate, and polyacrylamide; The conductive solute is any one of aluminum nitrate, sodium chloride, ammonium chloride, and potassium nitrate; The solvent A is one or both of isopropyl alcohol and ethylene glycol.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the dispersant to the silicon carbide nanowires is 1:1-2; The mass ratio of the conductive solute to the silicon carbide nanowires is 1:0.01-0.

1.

5. The preparation method according to claim 1, characterized in that, The anode used in the electrophoretic deposition treatment is a platinum sheet, the distance between the electrodes is 0.5-2 cm, and a constant voltage of 50-100 V is applied; And during the electrophoretic deposition treatment, keep the suspension of silicon carbide nanowires in a homogeneous component state.

6. A SiC nanowire network functional thin film prepared by the preparation method according to any one of claims 1-5.

7. An application of the SiC nanowire network functional thin film according to claim 6 in the preparation of SiC nano-optoelectronic devices.

8. The application according to claim 7, wherein Before being used for the preparation of SiC nano-optoelectronic devices, it also undergoes the following treatment: Adopt the thermal electron beam evaporation method to evaporate an ordered metal electrode array on the silicon carbide nanowire thin film B or the silicon carbide nanowire thin film C, perform annealing treatment, and then use a PVA glue solution for physical peeling to obtain a silicon carbide nanowire thin film D, and use the silicon carbide nanowire thin film D for the preparation of SiC nano-optoelectronic devices.

Images