A nanoparticle-enhanced AlGaN-based deep ultraviolet LED and its preparation method

Abstract

The present invention discloses an AlGaN-based deep ultraviolet LED based on nanoparticle enhancement and a preparation method, which relates to the technical field of deep ultraviolet LEDs. The method comprises a substrate, an N-type epitaxial layer prepared on the substrate, and a nanowire array prepared on the N-type epitaxial layer, wherein the nanowire array comprises a plurality of nanowires arranged at intervals, and the length direction of the nanowires is perpendicular to the surface of the N-type epitaxial layer; in the nanowire array, a plurality of nanoparticles for generating localized surface plasmon resonance are filled between adjacent nanowires. The present invention fills nanoparticles between adjacent nanowires of the nanowire array, which can enhance the light extraction efficiency of the AlGaN-based deep ultraviolet LED, thereby improving the luminous efficiency of the AlGaN-based deep ultraviolet LED.

Description

Technical Field

[0001] The invention relates to the technical field of deep ultraviolet LEDs, in particular to an AlGaN-based deep ultraviolet LED enhanced by nanoparticles and a preparation method thereof. Background Art

[0002] With the rapid development of modern information technology and optical communication technology, people have put forward higher requirements for the performance of light sources. Deep ultraviolet LEDs based on AlGaN semiconductors have great application prospects in many fields due to their advantages such as non-toxicity, small size, low energy consumption, long life, and adjustable wavelength, such as water and air purification, surface sterilization and disinfection, optical storage, 3D printing, ultraviolet lithography, non-line-of-sight communication, gas sensing, ultraviolet phototherapy, ink curing, and anti-counterfeiting detection. However, the luminous efficiency of AlGaN-based deep ultraviolet LEDs is very low. For devices with a wavelength between 270 and 280nm, the maximum external quantum efficiency (EQE) of AlGaN-based deep ultraviolet LEDs is about 20%, which is much lower than that of InGaN-based blue light LEDs. Therefore, improving the light extraction efficiency of AlGaN-based deep ultraviolet LEDs is crucial to the development of high-brightness deep ultraviolet LEDs.

[0003] General AlGaN-based deep ultraviolet LEDs all use epitaxially grown planar thin film structures, which have the advantages of mature growth technology and good film quality. However, the external quantum efficiency of AlGaN-based deep ultraviolet LEDs with planar structures is too low. For devices with wavelengths less than 300nm, the external quantum efficiency is generally less than 10%. However, with the rise of nanotechnology, nanomaterials are playing an increasingly important role in the fields of information display and communication.

[0004] The AlGaN-based nanowire array structure is a new type of deep ultraviolet LED nanostructure, which has new physical or chemical properties superior to those of planar structures, such as large surface area to volume ratio, low dislocation density, high doping efficiency, etc. In addition, when photons are incident on the AlGaN nanowire array structure, some photons are absorbed, and photons that are not absorbed are also absorbed due to reflection or refraction, which improves the photon absorption efficiency, thereby improving the external quantum efficiency of the AlGaN-based deep ultraviolet LED.

[0005] High quantum efficiency AlGaN-based deep ultraviolet LEDs are crucial to the development of solid-state ultraviolet light sources. Although the use of nanowire array structures can improve the external quantum efficiency of AlGaN-based deep ultraviolet LEDs, in order to better meet the actual application, the external quantum efficiency of AlGaN-based nanowire array deep ultraviolet LEDs, that is, the luminous efficiency, can be further improved. Summary of the invention

[0006] In view of the above problems and technical requirements, the inventors have proposed a nanoparticle-enhanced AlGaN-based deep ultraviolet LED and a preparation method. The technical solution of the present invention is as follows:

[0007] A nanoparticle-enhanced AlGaN-based deep ultraviolet LED comprises a substrate, an N-type epitaxial layer prepared on the substrate, and a nanowire array prepared on the N-type epitaxial layer, wherein:

[0008] The nanowire array comprises a plurality of nanowires arranged at intervals, and the length direction of the nanowires is perpendicular to the surface of the N-type epitaxial layer; in the nanowire array, a plurality of nanoparticles for generating localized surface plasmon resonance are filled between adjacent nanowires.

[0009] A further technical solution is that the localized surface plasmon resonance frequency of the nanoparticles matches the target luminous frequency of the AlGaN-based deep ultraviolet LED.

[0010] A further technical solution is that the substrate includes a front side and a back side corresponding to the front side, and in the direction from the back side of the substrate to the front side of the substrate, any nanowire includes a stacked N-type buffer layer, an N-type doping layer, a quantum well light-emitting layer, a P-type electron blocking layer and a P-type doping layer in sequence.

[0011] A further technical solution is that the quantum well light emitting layer includes a plurality of quantum well layers for forming quantum wells;

[0012] Each quantum well layer includes a well layer and an epitaxial layer prepared on the well layer, and the thickness of the epitaxial layer is greater than the thickness of the well layer;

[0013] The material of the well layer includes Al 0.4 Ga 0.6 N, the material of the epitaxial layer includes Al 0.8 Ga 0.4 N;

[0014] The thickness of the well layer is in the range of 1 nm to 10 nm, and the thickness of the epitaxial layer is in the range of 8 nm to 30 nm.

[0015] A further technical solution is that when a plurality of nanoparticles are arranged between adjacent nanowires, the plurality of nanoparticles are arranged along a thickness direction of the substrate and / or along a direction perpendicular to the thickness of the substrate.

[0016] A further technical solution is that the diameter of the nanowires is in the range of 100nm-300nm, the length of the nanowires is in the range of 3μm-7μm, and the spacing between adjacent nanowires is in the range of 10nm-150nm;

[0017] The material of the nanoparticles includes Al, the nanoparticles are spherical, and the diameter of the nanoparticles ranges from 5nm to 150nm.

[0018] A further technical solution is that the substrate is a sapphire substrate;

[0019] The materials of the N-type buffer layer and the N-type epitaxial layer include aluminum nitride, the thickness of the N-type buffer layer is in the range of 1 μm-3 μm, and the thickness of the N-type epitaxial layer is in the range of 1 μm-2 μm;

[0020] The materials of the N-type doping layer and the P-type electron blocking layer include aluminum gallium nitride, the thickness of the N-type doping layer is in the range of 1 μm-2 μm, and the thickness of the P-type electron blocking layer is in the range of 10 nm-60 nm;

[0021] The material of the P-type doping layer includes gallium nitride, and the thickness of the P-type doping layer ranges from 200nm to 500nm.

[0022] A further technical solution is that the nanowire array is covered with an anode metal layer for forming an anode, and the N-type epitaxial layer is provided with a cathode metal layer for forming a cathode; the anode metal layer is in ohmic contact with the nanowire array, and the cathode metal layer is in ohmic contact with the N-type epitaxial layer.

[0023] A method for preparing a nanoparticle-enhanced AlGaN-based deep ultraviolet LED is used to prepare the above-mentioned AlGaN-based deep ultraviolet LED, and the preparation method comprises:

[0024] Providing a substrate, and preparing an N-type epitaxial layer and a nanowire array on the substrate;

[0025] The nanowire array comprises a plurality of nanowires arranged at intervals, and the length direction of the nanowires is perpendicular to the surface of the N-type epitaxial layer;

[0026] A plurality of nanoparticles for generating localized surface plasmon resonance are filled between adjacent nanowires in the nanowire array.

[0027] Its further technical solution is that the preparation method comprises:

[0028] An AlGaN-based epitaxial wafer is prepared by an MOCVD process on the front side of the substrate, wherein the AlGaN-based epitaxial wafer includes an N-type epitaxial base layer, an N-type doped base layer, a quantum well light-emitting base layer, a P-type electron blocking base layer and a P-type doped base layer in sequence from the back side of the substrate to the front side of the substrate;

[0029] Etching the AlGaN-based epitaxial wafer to prepare an N-type epitaxial layer and a nanowire array located on the N-type epitaxial layer;

[0030] A plurality of the nanoparticles are filled between adjacent nanowires in a nanowire array by using a spin coating process.

[0031] The beneficial technical effects of the present invention are:

[0032] The present invention fills nanoparticles between adjacent nanowires in a nanowire array. The localized surface plasmon resonance generated by the nanoparticles can localize light in the nanowire array, thereby enhancing the radiation attenuation rate and light extraction efficiency, thereby improving the luminous efficiency of AlGaN-based deep ultraviolet LEDs.

[0033] In addition, by matching the localized surface plasmon resonance frequency of the nanoparticles with the target luminescence frequency of the LED and achieving strong resonant coupling between the nanoparticles and the quantum well luminescent layer, the radiation recombination efficiency of the AlGaN-based deep ultraviolet LED can be further improved, thereby improving the luminescence quantum efficiency and overall photoelectric conversion efficiency of the AlGaN-based deep ultraviolet LED and enhancing the overall performance of the AlGaN-based deep ultraviolet LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a cross-sectional schematic diagram of an embodiment of an AlGaN-based deep ultraviolet LED enhanced by nanoparticles provided by the present invention.

[0035] Figure 2 This is a comparison result of the light extraction efficiency between the conventional nanowire array AlGaN-based deep ultraviolet LED provided by the present invention and the AlGaN-based deep ultraviolet LED with additional nanoparticles.

[0036] Figure numerals: 1-substrate, 2-N-type epitaxial layer, 3-N-type buffer layer, 4-N-type doped layer, 5-quantum well light-emitting layer, 51-well layer, 52-epi layer, 6-P-type electron blocking layer, 7-P-type doped layer, 8-nanoparticles, 9-anode metal, 10-cathode metal. DETAILED DESCRIPTION

[0037] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0038] In order to improve the luminous efficiency of AlGaN-based deep ultraviolet LEDs, the present invention proposes an AlGaN-based deep ultraviolet LED based on nanoparticle enhancement, comprising a substrate 1, an N-type epitaxial layer 2 prepared on the substrate 1, and a nanowire array prepared on the N-type epitaxial layer 2, wherein:

[0039] The nanowire array includes a plurality of nanowires arranged at intervals, and the length direction of the nanowires is perpendicular to the surface of the N-type epitaxial layer 2 ; in the nanowire array, a plurality of nanoparticles 8 for generating localized surface plasmon resonance are filled between adjacent nanowires.

[0040] Specifically, the substrate 1 includes a front side and a back side corresponding to the front side, the N-type epitaxial layer 2 is prepared on the front side of the substrate 1, and the nanowire array is an array structure formed on the surface of the N-type epitaxial layer 2 by vertically arranging a plurality of nanowires at intervals, and the diameter, length and spacing between adjacent nanowires in the array may be the same or different. The surface of the N-type epitaxial layer 2 refers to the plane of the N-type epitaxial layer 2 away from the substrate 1. In this embodiment, the diameter range of the nanowire is 100nm-300nm, the length range of the nanowire is 3μm-7μm, and the spacing range between adjacent nanowires is 10nm-150nm. In specific implementation, the parameter ranges of the nanowires can be set according to the actual application.

[0041] In the present invention, a number of nanoparticles 8 are added in the nanowire gap formed by adjacent nanowires, and the number of nanoparticles 8 in each nanowire gap in the array may be the same or different. The free electrons in the nanoparticles 8 can interact with light waves to produce a collective oscillation phenomenon, that is, to produce a localized surface plasmon resonance (LSPR). The localized surface plasmon resonance generated by the nanoparticles 8 can greatly enhance the local electromagnetic field, thereby effectively localizing the light in the nanowire array, enhancing the radiation attenuation rate, improving the light extraction efficiency (LEE), and solving the problem of low light extraction efficiency of deep ultraviolet LEDs in transverse magnetic polarization, thereby improving the luminous efficiency of AlGaN-based deep ultraviolet LEDs. In this embodiment, the nanoparticles 8 are metal spherical nanoparticles, the material of which can be metal aluminum, and the diameter range of the nanoparticles 8 is 5nm-150nm. During specific implementation, the number and form of the nanoparticles 8 can be selected according to actual needs.

[0042] Preferably, the localized surface plasmon resonance frequency of the nanoparticles 8 matches the target emission frequency of the AlGaN-based deep ultraviolet LED. The matching means that the localized surface plasmon resonance frequency of the nanoparticles 8 is close to or equal to the target emission frequency of the AlGaN-based deep ultraviolet LED. When the localized surface plasmon resonance frequency of the nanoparticles 8 matches the target emission frequency of the AlGaN-based deep ultraviolet LED, a strong resonance absorption enhancement effect and a resonance scattering enhancement effect can be generated to further improve the luminous efficiency of the AlGaN-based deep ultraviolet LED.

[0043] When a plurality of nanoparticles 8 are arranged between adjacent nanowires, the plurality of nanoparticles 8 are arranged along the thickness direction of the substrate 1 and / or along a direction perpendicular to the thickness of the substrate 1, and the nanoparticles 8 are in contact with the N-type epitaxial layer 2, the corresponding nanowires and / or the adjacent nanoparticles 8. The arrangement of the nanoparticles 8 in each nanowire gap may be the same or different. Figure 1As shown, in this embodiment, the arrangement form and quantity of the nanoparticles 8 in each nanowire gap are the same, and the multiple nanoparticles 8 in each nanowire gap are arranged along the thickness direction of the substrate 1.

[0044] Furthermore, in the direction from the back side of the substrate to the front side of the substrate, any nanowire includes a stacked N-type buffer layer 3, an N-type doping layer 4, a quantum well light-emitting layer 5, a P-type electron blocking layer 6 and a P-type doping layer 7 in sequence.

[0045] Specifically, the quantum well light emitting layer 5 is a layered structure that utilizes the quantum confinement effect to realize light emission, and includes several quantum well layers for forming quantum wells, that is, each quantum well layer forms a quantum well, and the quantum well layer includes a well layer 51 and an epitaxial layer 52 prepared on the well layer 51, and the thickness of the epitaxial layer 52 is greater than the thickness of the well layer 51. In this embodiment, the quantum well light emitting layer 5 includes a total of 3 quantum well layers, and the structural parameters of the quantum well layers are consistent. The material of the well layer 51 can be Al 0.4 Ga 0.6 N, the material of the epitaxial layer 52 can be Al 0.6 Ga 0.4 N, the thickness of the well layer 51 ranges from 1nm to 10nm, and the thickness of the epitaxial layer 52 ranges from 8nm to 30nm. In specific implementation, the number of quantum well layers can be selected according to actual application requirements, and the thickness and material of the well layer 51 and the epitaxial layer 52 can also be selected according to actual application requirements.

[0046] Preferably, the nanoparticles 8 form a resonant coupling with the quantum well light-emitting layer 5 to improve the radiation recombination efficiency of carriers in the AlGaN-based deep ultraviolet LED, thereby improving the luminous quantum efficiency and overall photoelectric conversion efficiency of the AlGaN-based deep ultraviolet LED, and improving the overall performance of the AlGaN-based deep ultraviolet LED. The definition of the resonant coupling between the nanoparticles 8 and the quantum well light-emitting layer 5 is consistent with the prior art and is not repeated here.

[0047] Optionally, the substrate 1 is a sapphire substrate; the material of the N-type buffer layer 3 and the N-type epitaxial layer 2 is aluminum nitride (AlN), and the thickness of the N-type buffer layer 3 is in the range of 1μm-3μm; the thickness of the N-type epitaxial layer 2 is in the range of 1μm-2μm. The material of the N-type doping layer 4 and the P-type electron blocking layer 6 includes aluminum gallium nitride (AlGaN), and the thickness of the N-type doping layer 4 is in the range of 1μm-2μm; the thickness of the P-type electron blocking layer 6 is in the range of 10nm-60nm; the material of the P-type doping layer 7 includes gallium nitride (GaN), and the thickness of the P-type doping layer 7 is in the range of 200nm-500nm. In specific implementation, the materials and thicknesses of the substrate 1, the N-type epitaxial layer 2, the N-type buffer layer 3, the N-type doping layer 4, the P-type electron blocking layer 6 and the P-type doping layer 7 can be selected according to actual needs.

[0048] The nanowire array is covered with an anode metal layer 9 for forming an anode, and the N-type epitaxial layer 2 is provided with a cathode metal layer 10 for forming a cathode; the anode metal layer 9 is in ohmic contact with the nanowire array, and the cathode metal layer 10 is in ohmic contact with the N-type epitaxial layer 2.

[0049] Specifically, the anode metal layer 9 is in ohmic contact with all the P-type doped layers 7, and the material of the anode metal layer 9 can be metal nickel (Ni) / gold (Au). The thickness of the nickel in the anode metal layer 9 is between 3nm-30nm, and the thickness of the gold is between 3nm-30nm. The material of the cathode metal layer 10 can be metal titanium (Ti) / gold (Au), and the thickness of the titanium in the cathode metal layer 10 is between 5nm-30nm; the thickness of the gold in the cathode metal layer 10 is between 30nm-100nm.

[0050] The present invention also compares the light extraction efficiency of the conventional nanowire array AlGaN-based deep ultraviolet LED and the light extraction efficiency of the AlGaN-based deep ultraviolet LED with additional nanoparticles proposed in the present invention. Figure 2 As shown, the solid line represents the light extraction efficiency of the traditional nanowire array AlGaN-based deep ultraviolet LED in the deep ultraviolet band, and the dotted line represents the light extraction efficiency of the AlGaN-based deep ultraviolet LED with additional nanoparticles in the deep ultraviolet band. Figure 2 It can be seen that compared with traditional nanowire array AlGaN-based deep ultraviolet LEDs, the light extraction efficiency of AlGaN-based deep ultraviolet LEDs with added nanoparticles is generally enhanced in the deep ultraviolet band, and the light extraction efficiency can be enhanced by up to 37% (at a wavelength of 275nm), which shows that the nanoparticle-enhanced AlGaN-based deep ultraviolet LED provided by the present invention can effectively enhance the light extraction efficiency of AlGaN-based deep ultraviolet LEDs, thereby improving their luminous efficiency.

[0051] Furthermore, the present invention also provides a method for preparing a nanoparticle-enhanced AlGaN-based deep ultraviolet LED, the preparation method comprising:

[0052] Providing a substrate 1, and preparing an N-type epitaxial layer 2 and a nanowire array on the substrate 1;

[0053] The nanowire array comprises a plurality of nanowires arranged at intervals, and the length direction of the nanowires is perpendicular to the surface of the N-type epitaxial layer 2;

[0054] A plurality of nanoparticles 8 for generating localized surface plasmon resonance are filled between adjacent nanowires in the nanowire array.

[0055] Specifically, the method for preparing the nanoparticle-enhanced AlGaN-based deep ultraviolet LED comprises the following steps:

[0056] (1) providing a sapphire substrate, and preparing an AlGaN-based epitaxial wafer on the front side of the sapphire substrate by a MOCVD (Metal-organic Chemical Vapor Deposition) process, wherein:

[0057] The AlGaN-based epitaxial wafer includes, in order from the back side of the substrate to the front side of the substrate, an N-type epitaxial base layer, an N-type doped base layer, a quantum well light-emitting base layer, a P-type electron blocking base layer and a P-type doped base layer;

[0058] The material of the N-type epitaxial base layer is AlN, and the thickness of the N-type epitaxial base layer is in the range of 2 μm-5 μm. The material of the N-type doped base layer is AlGaN, and the thickness of the N-type doped base layer is in the range of 1 μm-2 μm.

[0059] The quantum well light emitting substrate comprises several layers of quantum well substrates, the quantum well substrate comprises a well substrate and an epitaxial substrate prepared on the well substrate, and the material of the well substrate can be Al 0.4 Ga 0.6 N, the epitaxy layer can be made of Al 0.6 Ga 0.4 N, the thickness of the well base layer is in the range of 1nm-10nm, and the thickness of the epitaxy base layer is in the range of 8nm-30nm.

[0060] The material of the P-type electron blocking layer is AlGaN, and the thickness of the P-type electron blocking layer is in the range of 10nm-60nm. The material of the P-type doping layer includes GaN, and the thickness of the P-type doping layer is in the range of 200nm-500nm.

[0061] (2) Etching the AlGaN-based epitaxial wafer to prepare an N-type epitaxial layer 2 and a nanowire array located on the N-type epitaxial layer 2.

[0062] Specifically, a soft UV-curing nanoimprint process and an inductively coupled plasma dry etching process are used to etch nanoscale grooves on an AlGaN-based epitaxial wafer to prepare a nanowire array. The nanoscale grooves extend to 1 μm-3 μm of the thickness of the N-type epitaxial base layer, so that the N-type epitaxial base layer that has not been etched is used to form an N-type epitaxial layer 2 with a thickness ranging from 1 μm to 2 μm.

[0063] The nanowire includes, from bottom to top, a stacked N-type buffer layer 3, an N-type doped layer 4, a quantum well light-emitting layer 5, a P-type electron blocking layer 6, and a P-type doped layer 7. The N-type buffer layer 3, the N-type doped layer 4, the quantum well light-emitting layer 5, the P-type electron blocking layer 6, and the P-type doped layer 7 are prepared in sequence using the above-mentioned N-type epitaxial base layer, the N-type doped base layer, the quantum well light-emitting base layer, the P-type electron blocking base layer, and the P-type doped base layer. The structure and structural parameters of the nanowire are consistent with those described above, and will not be repeated here.

[0064] (3) Using a spin coating method, fill the gaps between adjacent nanowires in the nanowire array with metal aluminum nanoparticles 8. The structural parameters and form of the nanoparticles 8 can refer to the above description.

[0065] (4) Depositing metal nickel / gold on the surface of the nanowire array to form an anode metal layer 9, the thickness parameters of the anode metal layer 9 are consistent with those mentioned above.

[0066] (5) Depositing metal titanium / gold on the surface of the N-type epitaxial layer 2 to form a cathode metal layer 10, the thickness parameters of the cathode metal layer 10 are consistent with the above.

[0067] The preparation method of the nanoparticle-enhanced AlGaN-based deep ultraviolet LED provided by the present invention is compatible with the prior art in terms of preparation process, has low preparation cost, and is suitable for wide application.

[0068] It should be noted that the words "front" and "back", "inner" and "outer" used in the above description refer to directions toward or away from a particular component, respectively. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0069] The above is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A nanoparticle-enhanced AlGaN-based deep ultraviolet LED, characterized in that: It includes a substrate, an N-type epitaxial layer prepared on the substrate, and a nanowire array prepared on the N-type epitaxial layer, wherein: The nanowire array comprises a plurality of nanowires arranged at intervals, wherein the length direction of the nanowires is perpendicular to the surface of the N-type epitaxial layer; in the nanowire array, a plurality of nanoparticles for generating localized surface plasmon resonance are filled between adjacent nanowires.

2. The nanoparticle-enhanced AlGaN-based deep ultraviolet LED according to claim 1, characterized in that: The localized surface plasmon resonance frequency of the nanoparticles matches the target luminous frequency of the AlGaN-based deep ultraviolet LED.

3. The nanoparticle-enhanced AlGaN-based deep ultraviolet LED according to claim 1, characterized in that: The substrate includes a front side and a back side corresponding to the front side. In the direction from the back side of the substrate to the front side of the substrate, any nanowire includes a stacked N-type buffer layer, an N-type doping layer, a quantum well light-emitting layer, a P-type electron blocking layer and a P-type doping layer in sequence.

4. The nanoparticle-enhanced AlGaN-based deep ultraviolet LED according to claim 3, characterized in that: The quantum well light-emitting layer includes a plurality of quantum well layers for forming quantum wells; Each quantum well layer includes a well layer and an epitaxial layer prepared on the well layer, and the thickness of the epitaxial layer is greater than the thickness of the well layer; The material of the well layer includes Al 0.4 Ga 0.6 N, the material of the epitaxial layer includes Al 0.6 Ga 0.4 N; The thickness of the well layer is in the range of 1 nm to 10 nm, and the thickness of the epitaxial layer is in the range of 8 nm to 30 nm.

5. The nanoparticle-enhanced AlGaN-based deep ultraviolet LED according to claim 1, characterized in that: When a plurality of nanoparticles are disposed between adjacent nanowires, the plurality of nanoparticles are arranged along a thickness direction of the substrate and / or along a direction perpendicular to the thickness of the substrate.

6. The nanoparticle-enhanced AlGaN-based deep ultraviolet LED according to claim 1, characterized in that: The diameter of the nanowires ranges from 100nm to 300nm, the length of the nanowires ranges from 3μm to 7μm, and the spacing between adjacent nanowires ranges from 10nm to 150nm; The material of the nanoparticles includes Al, the nanoparticles are spherical, and the diameter of the nanoparticles ranges from 5nm to 150nm.

7. The nanoparticle-enhanced AlGaN-based deep ultraviolet LED according to claim 3, characterized in that: The substrate is a sapphire substrate; The materials of the N-type buffer layer and the N-type epitaxial layer include aluminum nitride, the thickness of the N-type buffer layer is in the range of 1 μm-3 μm, and the thickness of the N-type epitaxial layer is in the range of 1 μm-2 μm; The materials of the N-type doping layer and the P-type electron blocking layer include aluminum gallium nitride, the thickness of the N-type doping layer is in the range of 1 μm-2 μm, and the thickness of the P-type electron blocking layer is in the range of 10 nm-60 nm; The material of the P-type doping layer includes gallium nitride, and the thickness of the P-type doping layer ranges from 200nm to 500nm.

8. The nanoparticle-enhanced AlGaN-based deep ultraviolet LED according to claim 1, characterized in that: The nanowire array is covered with an anode metal layer for forming an anode, and the N-type epitaxial layer is provided with a cathode metal layer for forming a cathode; the anode metal layer is in ohmic contact with the nanowire array, and the cathode metal layer is in ohmic contact with the N-type epitaxial layer.

9. A method for preparing a nanoparticle-enhanced AlGaN-based deep ultraviolet LED, characterized in that: For preparing the AlGaN-based deep ultraviolet LED according to any one of claims 1 to 8, the preparation method comprising: Providing a substrate, and preparing an N-type epitaxial layer and a nanowire array on the substrate; The nanowire array comprises a plurality of nanowires arranged at intervals, and the length direction of the nanowires is perpendicular to the surface of the N-type epitaxial layer; A plurality of nanoparticles for generating localized surface plasmon resonance are filled between adjacent nanowires in the nanowire array.

10. The method for preparing nanoparticle-enhanced AlGaN-based deep ultraviolet LED according to claim 9, characterized in that: The preparation method comprises: An AlGaN-based epitaxial wafer is prepared by an MOCVD process on the front side of the substrate, wherein the AlGaN-based epitaxial wafer includes an N-type epitaxial base layer, an N-type doped base layer, a quantum well light-emitting base layer, a P-type electron blocking base layer and a P-type doped base layer in sequence from the back side of the substrate to the front side of the substrate; Etching the AlGaN-based epitaxial wafer to prepare an N-type epitaxial layer and a nanowire array located on the N-type epitaxial layer; A plurality of the nanoparticles are filled between adjacent nanowires in a nanowire array by using a spin coating process.

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