Transparent electrode of deep ultraviolet LED and manufacturing method for transparent electrode

Abstract

The present application relates to a transparent electrode of a deep ultraviolet LED and a manufacturing method for the transparent electrode. The method comprises: depositing a silver thin film on an epitaxial structure of a deep ultraviolet LED; spin-coating a carbon nanotube suspension on the silver thin film; drying the epitaxial structure, and then performing a first rapid annealing in an inert atmosphere to form a silver / carbon nanotube composite structure composed of carbon nanotubes and silver nanospheres attached to the walls of the carbon nanotubes; depositing an aluminum oxide thin film on the silver / carbon nanotube composite structure; and performing a second rapid annealing in an inert atmosphere to form a transparent electrode of a silver / carbon nanotube / aluminum oxide composite structure. The transparent electrode has strong bonding strength and mechanical strength, and good light transmittance and conductivity.

Description

Transparent electrode of deep ultraviolet LED and preparation method thereof

[0001] The present application claims priority to the Chinese patent application No. CN202411333947.4, filed on September 24, 2024, and entitled "Transparent electrode of deep ultraviolet LED and preparation method thereof", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of optoelectronic materials, in particular to a transparent electrode of deep ultraviolet LED and a preparation method thereof. BACKGROUND

[0003] As a new type of optoelectronic device, deep ultraviolet LED needs electrode materials with high light transmittance and high conductivity to improve photoelectric conversion efficiency. Traditional transparent electrode materials such as indium tin oxide (ITO) have problems such as high brittleness and poor deep ultraviolet effect, and alternative materials need to be found. Carbon nanotubes are considered as ideal transparent electrode replacement materials due to their high light transmittance, conductivity and flexibility.

[0004] However, there are also some problems in the use of carbon nanotubes in transparent electrodes. When directly using carbon nanotubes as transparent electrodes, there is a problem of insufficient bonding strength with the LED epitaxial structure, resulting in loss of related properties such as conductivity; when carbon nanotubes are doped with metal or metal oxide to improve overall performance, chemical electroplating or direct deposition methods are often used to deposit metal on the surface of carbon nanotubes to form a composite structure, which can easily cause metal accumulation on the surface of carbon nanotubes, resulting in reduced light transmittance. There is a need for a method that can strengthen the bonding strength of carbon nanotubes with deep ultraviolet LED epitaxial structure without affecting light transmittance and conductivity. SUMMARY

[0005] In view of the technical problems existing in the prior art, the primary object of the present application is to provide a transparent electrode of deep ultraviolet LED and a preparation method thereof, which can strengthen the bonding strength of carbon nanotubes with the chip and its conductivity while ensuring light transmittance and conductivity, and add an aluminum oxide film on the top layer that can ensure bonding strength without affecting conductivity and light transmittance, so that the comprehensive performance of the transparent electrode is improved.

[0006] In one aspect, the present application provides a preparation method of a transparent electrode of deep ultraviolet LED, comprising the following steps:

[0007] depositing a silver film on the deep ultraviolet LED epitaxial structure;

[0008] spinning the carbon nanotube suspension on the silver film and drying;

[0009] After the drying, a first rapid annealing is performed in an inert atmosphere, a silver / carbon nanotube composite structure composed of carbon nanotubes and silver nanospheres attached to the wall of the carbon nanotubes is formed on the deep ultraviolet LED epitaxial structure;

[0010] A layer of aluminum oxide film is deposited on the silver / carbon nanotube composite structure;

[0011] A second rapid annealing is performed in an inert atmosphere to form the transparent electrode of the silver / carbon nanotube / aluminum oxide composite structure.

[0012] Further, the thickness of the silver film is 2-10 nm.

[0013] Further, the deposition process for depositing a layer of silver film is a thermal evaporation process.

[0014] Further, the growth rate in the thermal evaporation process is 0.3 nm / s.

[0015] Further, the carbon nanotube suspension is prepared by mixing carbon nanotubes, a solvent and a surface active agent and then ultrasonicating, the surface active agent is sodium dodecyl benzene sulfonate or sodium dodecyl sulfate, the mass fraction of carbon nanotubes in the carbon nanotube suspension is 1%-20%, and the ultrasonicating time is 30-120 min.

[0016] Further, the solvent is an organic solvent or an inorganic solvent, the organic solvent includes anhydrous ethanol or acetone, and the inorganic solvent is deionized water.

[0017] Further, the rotation speed of the spin coating is 1000-4000 rpm, and the spin coating time is 1-10 min.

[0018] Further, the thickness of the aluminum oxide film layer is 10-100 nm.

[0019] Further, the deposition of the layer of aluminum oxide film is performed by a magnetron sputtering process.

[0020] Further, the inert atmosphere of the first rapid annealing is a nitrogen atmosphere, the temperature of the first rapid annealing is 300-700℃, and the annealing time is 30 s-120 s;

[0021] The inert atmosphere of the second rapid annealing is a nitrogen atmosphere, the temperature of the second rapid annealing is 300-700℃, and the annealing time is 30 s-120 s.

[0022] Further, during the first rapid annealing and the second rapid annealing, the flow rate of nitrogen is 0.5 L / min.

[0023] The other aspect of the present application provides a transparent electrode of a deep ultraviolet LED, which is arranged on a deep ultraviolet LED epitaxial structure, and is a silver / carbon nanotube / aluminum oxide composite structure, which is composed of a silver / carbon nanotube composite structure and an aluminum oxide film layer covering the silver / carbon nanotube composite structure, and the silver / carbon nanotube composite structure is composed of a carbon nanotube layer and silver nanospheres attached to the wall of the carbon nanotube.

[0024] Further, the thickness of the aluminum oxide film layer is 10-100 nm.

[0025] Further, the particle size of the silver nanospheres is 2-10 nm.

[0026] Further, the carbon nanotubes are at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes; and the carbon nanotube layer is one to three layers.

[0027] The silver / carbon nanotube composite structure is obtained by thermal evaporation of a silver layer on the deep ultraviolet LED epitaxial structure, followed by spin coating of a carbon nanotube layer on the silver layer, and finally annealing.

[0028] Further, the present application also provides a deep ultraviolet LED comprising the above-mentioned transparent electrode of a deep ultraviolet LED.

[0029] Compared with the prior art, the present application has at least the following beneficial effects:

[0030] Based on the good transmittance of carbon nanotubes and aluminum oxide to deep ultraviolet light, the present application forms a silver / carbon nanotube composite structure by arranging silver nanospheres on the wall of the carbon nanotube, which improves the bonding strength between the carbon nanotube layer and the deep ultraviolet LED epitaxial structure while ensuring the light transmittance and excellent electrical conductivity, and forms a transparent electrode of a silver / carbon nanotube / aluminum oxide composite structure by arranging an aluminum oxide film layer on the silver / carbon nanotube composite structure, which protects the carbon nanotube and further strengthens the bonding strength and mechanical strength of the transparent electrode, and obtains a deep ultraviolet transparent electrode with good light transmittance and electrical conductivity.

[0031] The application avoids the problem of uneven accumulation of metal caused by chemical plating and the like. The preparation method of the application forms silver nanospheres attached to the wall of carbon nanotubes by depositing a silver thin film on a deep ultraviolet LED epitaxial structure, then spin-coating carbon nanotubes on the silver thin film, using the annealing ball gathering property of silver, and forming silver / carbon nanotube composite structure after rapid annealing, which improves the bonding strength between the carbon nanotube layer and the deep ultraviolet LED epitaxial structure while ensuring light transmittance and excellent electrical conductivity. Further, an aluminum oxide thin film is deposited on the silver / carbon nanotube composite structure to form a silver / carbon nanotube / aluminum oxide composite structure transparent electrode, which has high retention rate, good bonding strength and light transmittance, and excellent electrical conductivity. BRIEF DESCRIPTION OF DRAWINGS

[0032] Fig. 1 is a schematic diagram of the application after spin-coating a carbon nanotube suspension in an embodiment of the application.

[0033] Fig. 2 is a schematic diagram of the silver / carbon nanotube / aluminum oxide composite structure obtained in an embodiment of the application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the application will be described clearly and completely in combination with the drawings of the application. The described embodiments are only some of the embodiments of the application, not all. Based on the embodiments in the application, other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application. In the following embodiments, the experimental methods are conventional methods unless otherwise specified. The reagents and materials can be obtained from public commercial channels unless otherwise specified.

[0035] Spatial relative terms such as "under", "below", "lower", "on", "above", "upper" and the like, are used herein for explaining the position of an element relative to the second element. These terms are intended to encompass different orientations of the device, except for those different from the orientations shown in the drawings.

[0036] In addition, terms such as "first", "second" and the like are used to describe various elements, layers, regions, segments and the like, and are not intended to be limiting. "Have", "contain", "include", "comprise" and the like are open terms, indicating the presence of the stated elements or features, but not excluding additional elements or features. Unless the context clearly indicates otherwise.

[0037] The transparent electrode of the deep ultraviolet LED is formed on a deep ultraviolet LED epitaxial structure. The transparent electrode of the deep ultraviolet LED comprises a silver / carbon nanotube composite structure formed on the deep ultraviolet LED epitaxial structure and an aluminum oxide film layer covering the silver / carbon nanotube composite structure, wherein the thickness of the aluminum oxide film layer is 10-100 nm, which ensures the ultraviolet light transmission performance of the electrode; and the aluminum oxide film layer is preferably deposited on the silver / carbon nanotube composite structure by a magnetron sputtering process, or other suitable deposition processes can also be selected.

[0038] The silver / carbon nanotube composite structure comprises a carbon nanotube layer and silver nanospheres attached to the wall of the carbon nanotube, the carbon nanotube layer is a single-layer carbon nanotube, a double-layer carbon nanotube or a triple-layer carbon nanotube, and the carbon nanotube is at least one of a single-walled carbon nanotube and a multi-walled carbon nanotube. The silver / carbon nanotube composite structure is obtained by the following process: a silver film is thermally evaporated on the deep ultraviolet LED epitaxial structure, then a carbon nanotube layer is spin-coated on the silver film, and finally an annealing process is performed. The silver / carbon nanotube composite structure obtained by this process avoids the problems of uneven deposition and accumulation of silver electroplated on the carbon nanotube in the traditional process. This method utilizes the annealing ball gathering characteristics of silver to form silver nanospheres on the wall of the carbon nanotube, thereby improving the bonding strength of the carbon nanotube and the chip and ensuring the light transmission performance of the electrode.

[0039] The application also provides a preparation method of the transparent electrode of the deep ultraviolet LED, which comprises the following steps:

[0040] First, a silver film with a thickness of 2-10 nm is deposited on the deep ultraviolet LED epitaxial structure. The deposition process is selected, for example, a thermal evaporation process. In a preferred embodiment, the deposition thickness of the silver film is 5 nm, 7 nm or 10 nm, the internal state of the evaporation chamber is vacuum (about 6*10 -4 Pa), and the growth rate is about 0.3 nm / s.

[0041] The carbon nanotube, a solvent and a surface activator are prepared into a suspension. The carbon nanotube can comprise at least one of a single-walled carbon nanotube and a multi-walled carbon nanotube. The surface activator is sodium dodecyl benzene sulfonate or sodium dodecyl sulfate; and the surface activator is added to ensure the high dispersibility of the carbon nanotube. The solvent is an organic solvent or an inorganic solvent, for example, anhydrous ethanol or acetone, etc., or deionized water. After the carbon nanotube, the solvent and the surface activator are mixed, ultrasonic treatment is performed to obtain the suspension, the ultrasonic treatment time is 30-120 min, and the mass proportion of the carbon nanotube in the prepared suspension is 1%-20%. In a preferred embodiment, the mass proportion of the carbon nanotube in the prepared suspension is 5%, the amount of sodium dodecyl benzene sulfonate added is 0.2 g / L, and the ultrasonic treatment time is 30 min to obtain the carbon nanotube suspension.

[0042] Then, the carbon nanotube suspension is spin-coated on the silver film, the spin-coating speed is 1000-4000 rpm, the spin-coating time is 1-10 min, and then the epitaxial structure is dried by heating. In a preferred embodiment, the silver film is spin-coated at a speed of 2000 rpm for 2 min, and then placed in an oven at 65°C for 15 min to obtain the dried deep ultraviolet LED epitaxial structure.

[0043] The dried deep ultraviolet LED epitaxial structure is placed in an annealing furnace for the first rapid annealing in a nitrogen atmosphere, the nitrogen flow rate is 0.5 L / min, the annealing temperature is 300-700°C, and the annealing time is 30 s-120 s, preferably 30 s-90 s, to obtain a silver / carbon nanotube composite structure formed on the deep ultraviolet LED epitaxial structure, which is composed of a carbon nanotube layer and silver nanospheres attached to the wall of the carbon nanotube. In a preferred embodiment, the annealing temperature is 500°C, and the annealing time is 1 min.

[0044] Then, an aluminum oxide film layer with a thickness of 10-100 nm is deposited on the silver / carbon nanotube composite structure. In an embodiment, the aluminum oxide film layer is deposited by a magnetron sputtering process, which can obtain a high-quality film with high shape retention, uniform thickness, and high coverage. The sputtering thickness is controlled by controlling the sputtering time to be 22 min, 64 min, and 105 min, corresponding to a sputtering thickness of 20 nm, 60 nm, and 100 nm.

[0045] Then, the second rapid annealing is performed, and the epitaxial structure with the deposited aluminum oxide film layer is placed in an annealing furnace for annealing in a nitrogen atmosphere, the nitrogen flow rate is 0.5 L / min, the annealing temperature is 300-700°C, and the annealing time is 30 s-120 s, preferably 30 s-90 s, to form a silver / carbon nanotube / aluminum oxide composite structure transparent electrode. In a preferred embodiment, the annealing temperature is 400°C, 500°C, and 600°C, and the annealing time is 1 min.

[0046] Finally, a silver / carbon nanotube / aluminum oxide transparent electrode with good light transmittance, improved conductivity, and good bonding strength is obtained by the above preparation method.

[0047] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above embodiments, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are included in the protection scope of the present application.

Claims

1. A method of fabricating a transparent electrode of a deep ultraviolet LED, characterized by, The method comprises the following steps: depositing a silver film on the deep ultraviolet LED epitaxial structure; spinning a carbon nanotube suspension on the silver film and drying; carrying out a first rapid annealing in an inert atmosphere after drying, to form a silver / carbon nanotube composite structure on the deep ultraviolet LED epitaxial structure, the silver / carbon nanotube composite structure being composed of carbon nanotubes and silver nanospheres attached to the walls of the carbon nanotubes; depositing an aluminum oxide film layer on the silver / carbon nanotube composite structure; carrying out a second rapid annealing in an inert atmosphere to form a silver / carbon nanotube / aluminum oxide composite structure transparent electrode.

2. The production method according to claim 1, characterized by, The thickness of the silver film is 2-10 nm.

3. The production method according to claim 1 or 2, characterized by, The deposition process used in the step of depositing a silver film is a thermal evaporation process.

4. The production method according to claim 3, characterized by, The growth rate in the thermal evaporation process is 0.3 nm / s.

5. The preparation method according to claim 1, characterized in that, The carbon nanotube suspension is prepared by mixing carbon nanotubes, a solvent and a surface active agent, and then ultrasonicating, the surface active agent being sodium dodecyl benzene sulfonate or sodium dodecyl sulfate, the mass fraction of the carbon nanotubes in the carbon nanotube suspension being 1-20%, and the ultrasonicating time being 30-120 min.

6. The production method according to claim 5, wherein The solvent is an organic solvent or an inorganic solvent, the organic solvent including anhydrous ethanol or acetone, and the inorganic solvent being deionized water.

7. The production method according to claim 5 or 6, characterized by, The spinning speed is 1000-4000 rpm, and the spinning time is 1-10 min.

8. The production method according to claim 1 or 2, characterized by, The thickness of the aluminum oxide film layer is 10-100 nm.

9. The preparation method according to claim 8, characterized in that, The deposition of the aluminum oxide film layer uses a magnetron sputtering process.

10. The preparation method according to claim 8, characterized in that, The inert atmosphere for the first rapid annealing is a nitrogen atmosphere, the temperature for the first rapid annealing is 300-700 ℃, and the annealing time is 30 s-120 s; The inert atmosphere for the second rapid annealing is a nitrogen atmosphere, the temperature for the second rapid annealing is 300-700 ℃, and the annealing time is 30 s-120 s.

11. The method of claim 10, wherein, The flow rate of nitrogen during the first and second rapid annealings is 0.5 L / min.

12. A transparent electrode of a deep ultraviolet LED, the transparent electrode being disposed on a deep ultraviolet LED epitaxial structure, characterized in that, The transparent electrode is a silver / carbon nanotube / aluminum oxide composite structure, which is composed of a silver / carbon nanotube composite structure and an aluminum oxide film layer covering the silver / carbon nanotube composite structure, the silver / carbon nanotube composite structure being composed of a carbon nanotube layer and silver nanospheres attached to the walls of the carbon nanotubes.

13. The transparent electrode according to claim 12, wherein The thickness of the aluminum oxide film layer is 10-100 nm.

14. The transparent electrode according to claim 12 or 13, wherein The particle size of the silver nanospheres is 2-10 nm.

15. The transparent electrode according to claim 14, wherein The carbon nanotubes are at least one of single-walled carbon nanotubes and multi-walled carbon nanotubes, and the carbon nanotube layer has one to three layers.

16. A deep ultraviolet LED, comprising: The method comprises the steps of Claim 12-15. The method comprises the steps of Claim 12-15.

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