Deep ultraviolet light-emitting diode with patterned photon absorption structure and preparation method of deep ultraviolet light-emitting diode

Abstract

The invention relates to a deep ultraviolet light-emitting diode with a patterned photon absorption structure and a preparation method of the deep ultraviolet light-emitting diode. The diode sequentially comprises a substrate, an AlN buffer layer and an N-type AlGaN layer from bottom to top, wherein one side of the N-type AlGaN layer is partially exposed, and the multi-quantum well layer, the P-type electron barrier layer, the P-type AlGaN layer and the P-type GaN layer sequentially cover the upper surface of the unexposed part of the N-type AlGaN layer from bottom to top; oxide nano structures are distributed on the upper surface of the P-type GaN layer in an array manner; the P-type ohmic contact layer covers the oxide nanostructure and the P-type GaN layer, and an array distribution structure is also formed; and the metal reflector layer covers the P-type ohmic contact layer. According to the invention, the hole injection efficiency of the deep ultraviolet LED is improved, and the absorbed light is inhibited from being converted into heat energy.

Description

Technical Field

[0001] The invention relates to the technical field of light emitting diode semiconductors, in particular to a deep ultraviolet light emitting diode with a patterned photon absorption structure and a preparation method thereof. Background Art

[0002] With the continuous development of semiconductor device preparation technology, the research of ultraviolet light-emitting diodes has become an important topic. By alloying gallium nitride with aluminum nitride materials, the emission wavelength of gallium nitride-based LEDs can be adjusted to almost cover the entire ultraviolet (UV) spectrum range (200-400nm), among which the light-emitting diodes with a wavelength of 200nm to 280nm are called deep ultraviolet light-emitting diodes (DUV LEDs). Depending on their emission wavelengths, UV LED devices have broad application prospects in water purification, UV curing, optical communications, and phototherapy. Therefore, it is a goal to develop DUV LEDs with high external quantum efficiency (EQE), strong light power, and high electro-optical conversion efficiency (WPE). However, at this stage, deep ultraviolet LEDs still have low external quantum efficiency (EQE) and poor electro-optical conversion efficiency, which limits their further commercial application. Deep ultraviolet LEDs often use Mg as a p-type doping material, and the hole injection efficiency is limited due to the large activation energy of Mg and the low hole mobility. In addition, since the proportion of TM polarized light in deep ultraviolet LEDs is very large, and there are many absorbing materials in deep ultraviolet LEDs such as metals and pGaN, the light in deep ultraviolet LEDs is difficult to extract and is converted into heat, thereby reducing the light extraction efficiency of deep ultraviolet LEDs. Therefore, it is very important to increase the hole injection rate in LED multi-quantum wells and prevent the light of deep ultraviolet LEDs from being absorbed and converted into heat.

[0003] In the current technology, the patent "A Flip-chip Deep Ultraviolet Light Emitting Diode Chip and Its Preparation Method" (Publication No.: CN113410356A) mentions the roughening of the P-AlGaN layer, which is to use a sodium hydroxide solution of a specific concentration to corrode the P-AlGaN layer, and then dry-etch the surface of the corroded P-AlGaN layer. By changing the geometry of the interface between the P-AlGaN layer and the p-electrode and increasing the critical angle of total reflection, the metal reflectivity of the p-electrode is increased, thereby achieving the effect of improving the light extraction efficiency.

[0004] Although the above solution effectively improves the light extraction efficiency, the roughening of the P-AlGaN layer will sacrifice the area of ​​the ohmic contact, which will not only affect the current injection efficiency of the deep ultraviolet LED, but also increase power consumption and reduce the luminous efficiency of the deep ultraviolet LED. Summary of the invention

[0005] The purpose of the present invention is to provide a deep ultraviolet light-emitting diode with a patterned photon absorption structure and a preparation method thereof in view of the deficiencies in the current technology. The patterned photon absorption structure of the diode is a nanostructure of an n-type oxide layer made on the surface of a P-GaN layer of a conventional flip-chip deep ultraviolet LED by nanolithography and stripping technology, wherein the nanostructure can be a nanocolumn structure. Then, a p-electrode is evaporated on the oxide nanostructure, and the p-electrode can inject holes from the middle of the oxide of the nanostructure to realize the light emission of the deep ultraviolet LED. The present invention improves the hole injection efficiency of the deep ultraviolet LED and suppresses the conversion of absorbed light into heat energy.

[0006] The technical solution adopted by the present invention to solve the technical problem is as follows: A deep ultraviolet light-emitting diode having a patterned photon absorption structure, The diode includes a substrate, an AlN buffer layer, and an N-type AlGaN layer from bottom to top; one side of the N-type AlGaN layer is partially exposed, and the exposed area is 5-90% of the surface area of ​​the entire N-type AlGaN layer; the height of the exposed part is 5-90% of the height of the entire N-type AlGaN layer; The upper surface of the unexposed N-type AlGaN layer is covered with a multi-quantum well layer, a P-type electron blocking layer, a P-type AlGaN layer, and a P-type GaN layer in order from bottom to top; an array of oxide nanostructures is distributed on the upper surface of the P-type GaN layer; a P-type ohmic contact layer is covered on the oxide nanostructure and the P-type GaN layer, also forming an array distribution structure; The metal reflector layer covers the P-type ohmic contact layer; An N-type ohmic electrode is also distributed on the surface of the exposed portion of the N-type AlGaN layer; The material of the oxide nanostructure is n-type ZnO or n-type Ga2O3, and the doping concentration is 1*10e15-1*10e20 / cm 3 , thickness is between 5 and 500 nm; The nanostructure in the oxide nanostructure is a nanocolumn array, the diameter of which is 10nm-10000nm, the spacing between the nanocolumns is 10nm-10000nm, and the filling rate is 20-80%; The substrate is a C-plane sapphire substrate; The buffer layer material is AlN, with a thickness of 1~3μm; The material of N-type AlGaN layer is Al 0.6 Ga 0.4 N, thickness is 1~3μm; The structure of the multi-quantum well layer is 5 periods of Al 0.45 Ga 0.55 N / A 0.56Ga 0.44 N layers, where the quantum barrier Al 0.56 Ga 0.44 The thickness of N is set to 11~12nm, and the quantum well Al 0.45 Ga 0.55 The thickness of N is set to 3~4nm; The P-type electron blocking layer material is Al 0.6 Ga 0.4 N, thickness is 10~50nm; The material of the P-type AlGaN layer is Al 0.4 Ga 0.6 N, thickness is 50~200nm; The thickness of the P-type GaN layer is 10~50nm; The material of the P-type ohmic contact layer is Ni / Au or Ni / Al; The material of the metal reflector electrode is Al; The material of the N-type ohmic electrode is Cr / Au or Ti / Al / Ti / Au, wherein the projected area of ​​the N-type ohmic electrode is 10-80% of the area of ​​the exposed N-type AlGaN layer; The method for preparing a deep ultraviolet light-emitting diode having a patterned photon absorption structure comprises the following steps: The first step is to bake the substrate at 1250-1350°C in a MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy) reactor to remove foreign matter on the substrate surface, and then grow an AlN buffer layer, an N-type AlGaN layer, a multi-quantum well layer, a P-type electron blocking layer, a P-type AlGaN layer, and a P-type GaN layer on the sapphire substrate in sequence; In the second step, a positive photoresist layer is spin-coated on the P-type GaN layer obtained in the first step; In the third step, a single layer of nanosphere lens layer is attached to the photoresist layer obtained in the second step; Step 4: on the nanoball lens layer obtained in step 3, a photoresist nanostructure is fabricated by exposure and development process; Step 5, growing an oxide structure in the photoresist nanostructure by magnetron sputtering on the photoresist nanostructure obtained in the step 4; Step 6: stripping the photoresist mask and the oxide on the mask by a stripping technique to obtain an oxide nanostructure; Step 7: The table is made by photolithography and dry etching process, and the oxide nanostructure, P-type GaN layer, P-type AlGaN layer, P-type electron blocking layer, multi-quantum well layer, and N-type AlGaN layer are etched to form a DUV LED epitaxial layer structure that passes through the quantum well structure, and 5-90% of the N-type AlGaN layer is exposed; Step 8: Make a mask for the P-type ohmic contact layer by photolithography technology, so that the mask exposes 30% to 100% of the middle area of ​​the P-GaN table surface, deposit the P-type ohmic contact layer by electron beam evaporation or magnetron sputtering, and then peel off the mask and the P-type ohmic contact layer on the mask; Step 9: evaporate and photolithography an N-type ohmic electrode on the exposed N-type AlGaN layer, with an area of ​​10 to 80% of the area of ​​the exposed N-type AlGaN layer; The tenth step is to evaporate a metal mirror electrode on the exposed P-type ohmic contact layer.

[0007] The essential features of the present invention are: The luminous efficiency of deep ultraviolet LEDs in current technology is low, which limits further commercial applications. One reason is that the doping efficiency of Mg dopants in the P-type region is low and the hole mobility is low, which leads to limited hole injection efficiency. The unbalanced concentration of electrons and holes in the multi-quantum wells leads to low radiative recombination efficiency. In addition, since there is a very large proportion of TM polarized light in deep ultraviolet LEDs and there are many absorbing materials in deep ultraviolet LEDs, the light in deep ultraviolet LEDs is difficult to extract and is converted into heat, thereby reducing the luminous efficiency of deep ultraviolet LEDs.

[0008] In the present invention, a layer of oxide nanostructure is inserted between the P-type GaN layer and the P-type ohmic contact layer. The oxide of this structure can absorb deep ultraviolet photons that are difficult to escape from the deep ultraviolet LED, re-convert and excite electron-hole pairs, and re-inject them into the quantum well under the action of the electric field for electron-hole recombination luminescence, thereby greatly increasing the hole injection rate of the deep ultraviolet LED, promoting photon circulation, inhibiting the conversion of absorbed light into heat, and improving the overall luminous efficiency of the deep ultraviolet LED.

[0009] The beneficial effects of the present invention are: (1) The deep ultraviolet light-emitting diode of the present invention is characterized in that the hole injection efficiency of the deep ultraviolet LED is improved by recycling photons, and the conversion of absorbed light into heat energy is suppressed. A layer of oxide nanostructure is inserted between the P-type GaN layer and the P-type ohmic contact layer, which absorbs deep ultraviolet photons that are difficult to escape from the deep ultraviolet LED, excites electron-hole pairs, and the holes move under the action of the electric field, thereby doubling the hole injection rate in the quantum well and achieving a more balanced carrier concentration, enhancing the radiation recombination of the deep ultraviolet LED, promoting photon recycling, reducing heat generation, and thus improving the luminous efficiency of the deep ultraviolet LED.

[0010] (2) The deep ultraviolet light-emitting diode with a patterned photon absorption structure and the preparation method thereof of the present invention are based on the deep ultraviolet LED and use photolithography and stripping technology to make an oxide nanostructure. The process is simple and reliable, and the production cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be further described below in conjunction with the accompanying drawings.

[0012] Figure 1 This is a schematic diagram of the epitaxial structure of a flip-chip deep ultraviolet light-emitting diode LED chip that only has a metal reflector electrode structure in current technology.

[0013] Figure 2 It is a schematic diagram of the epitaxial structure of a deep ultraviolet light-emitting diode having a patterned photon absorption structure in the method of the present invention.

[0014] Figure 3 The present invention is a schematic diagram of an epitaxial wafer structure in which a layer of positive photoresist is spin-coated on a P-type GaN layer in the method of the present invention.

[0015] Figure 4 In the method of the present invention Figure 3 The product shown is a schematic diagram of the epitaxial wafer structure of a nano-lens made by nano-lithography technology.

[0016] Figure 5 In the method of the present invention Figure 4 The product shown is a schematic diagram of the structure of an epitaxial wafer with a photoresist nanostructure made through exposure and development processes.

[0017] Figure 6 In the method of the present invention Figure 5 The product shown is a schematic diagram of an epitaxial wafer structure in which an oxide structure is grown in a photoresist nanostructure by magnetron sputtering.

[0018] Figure 7 In the method of the present invention Figure 6 The product shown is a schematic diagram of the epitaxial wafer structure in which the photoresist mask and the oxide on the mask are stripped off by the stripping technology.

[0019] Figure 8 In the method of the present invention Figure 7 The product shown is a schematic diagram of the epitaxial wafer structure in which steps are made through photolithography and dry etching processes to expose the N-type AlGaN layer.

[0020] Fig. 9 In the method of the present invention Figure 8 Schematic diagram of the epitaxial wafer structure on which a P-type ohmic contact layer and an N-type ohmic electrode are respectively fabricated on the oxide nanostructure of the product and the exposed N-type AlGaN layer.

[0021] Fig.10 In the method of the present invention Fig. 9 Schematic diagram of the structure of making a metal mirror electrode on the P-type ohmic contact layer of the product shown.

[0022] Among them, 101. substrate, 102. AlN buffer layer, 103. N-type AlGaN layer, 104. multiple quantum well layer, 105. P-type electron blocking layer, 106. P-type AlGaN layer, 107. P-type GaN layer, 108. oxide nanostructure, 109. P-type ohmic contact layer, 110. metal mirror electrode, 111. N-type ohmic electrode, 112. photoresist layer, 113. nanolens layer, 114. photoresist nanostructure, 115 oxide layer. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with embodiments and drawings, but this is not intended to limit the scope of protection of the claims of this application.

[0024] Figure 1 The embodiment shown shows that the deep ultraviolet LED chip structure with a metal reflector electrode structure in the prior art includes, in sequence: a substrate 101, an AlN buffer layer 102, an N-type AlGaN layer 103, a multi-quantum well layer 104, a P-type electron blocking layer 105, a P-type AlGaN layer 106, a P-type GaN layer 107, a P-type ohmic contact layer 109, a metal reflector electrode 110, and an N-type ohmic electrode 111. For the deep ultraviolet LED structure of this structure, only a small part of the photons can escape from the sapphire substrate or be reflected by the metal reflector for reuse, and most of the photons are not effectively utilized.

[0025] Example 1 The structure of the deep ultraviolet light-emitting diode chip with a patterned photon absorption structure in this embodiment is as follows: Figure 2As shown, from bottom to top, it includes: a substrate 101, an AlN buffer layer 102, and an N-type AlGaN layer 103; wherein the right side of the N-type AlGaN layer 103 is partially exposed, and the exposed area is 5% of the surface area of ​​the entire N-type AlGaN layer 103; the height of the exposed portion is 5% of the height of the entire N-type AlGaN layer 103; The upper surface of the unexposed portion of the N-type AlGaN layer 103 is covered with a multi-quantum well layer 104, a P-type electron blocking layer 105, a P-type AlGaN layer 106, and a P-type GaN layer 107 in order from bottom to top; an array of oxide nanostructures 108 is distributed on the upper surface of the P-type GaN layer 107; a P-type ohmic contact layer 109 covers the oxide nanostructures 108 and the P-type GaN layer 107, also forming an array distribution structure; The metal reflector layer 110 covers the P-type ohmic contact layer 109; An N-type ohmic electrode 111 is also distributed on the surface of the exposed portion of the N-type AlGaN layer 103 ; the area of ​​the N-type ohmic electrode 111 is 80% of the area of ​​the exposed portion of the N-type AlGaN layer 103 ; The substrate 101 is made of sapphire, and the epitaxial growth of the structure is along the

[0001] direction. The substrate shape is square with a side length of 380μm; the buffer layer 102 is made of AlN and has a thickness of 2μm; the N-type AlGaN layer 103 is made of Al 0.6 Ga 0.4 N, with a thickness of 1 μm; the structure of the multi-quantum well layer 104 is 5 periods of Al 0.45 Ga 0.55 N / A 0.56 Ga 0.44 N layers, where the quantum barrier Al 0.56 Ga 0.44 The thickness of N is set to 12nm, and the quantum well Al 0.45 Ga 0.55 The thickness of N is set to 3nm; the material of P-type electron blocking layer 105 is Al 0.6 Ga 0.4 N, with a thickness of 20 nm; the material of the P-type AlGaN layer 106 is Al 0.4 Ga 0.6 N, with a thickness of 125 nm; the thickness of the P-type GaN layer 107 is 50 nm; the material of the oxide nanostructure 108 is cylindrical n-type ZnO with a doping concentration of 1*10e15 / cm 3, the diameter is 10000nm, the spacing is 10000nm, the filling rate is 20%, and the height is 500nm. The material of the P-type ohmic contact layer 109 is Ni / Au, which is evenly distributed on the surface of the P-type GaN layer 107 and the oxide nanostructure 108, and its minimum thickness in the horizontal direction is equal to the minimum thickness in the vertical direction, both of which are 20nm; the material of the metal reflector layer 110 is metal Al, which fills the spacing between the P-type ohmic contact layers 109, and its thickness above the P-type ohmic contact layer 109 is 200nm; the material of the N-type ohmic electrode 111 is Ti / Al / Ti / Au, with a thickness of 200nm and an area of ​​80% of the exposed part in the N-type AlGaN layer 103.

[0026] The preparation method of the above-mentioned deep ultraviolet light-emitting diode chip structure having a patterned photon absorption structure is as follows: In the first step, in a MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy) reactor, the substrate is baked at 1250-1350°C to remove foreign matter on the substrate surface, and then an AlN buffer layer 102 with a thickness of 2 μm and a growth temperature of 1250°C is grown on the sapphire substrate in sequence; an N-type AlGaN layer 103 with a thickness of 1 μm; and a multi-quantum well layer 104 with 5 periods of Al 0.45 Ga 0.55 N / A 0.56 Ga 0.44 N layers, where the quantum barrier Al 0.56 Ga 0.44 The thickness of N is 12nm, and the quantum well Al 0.45 Ga 0.55 N has a thickness of 3nm; P-type electron blocking layer 105 has a thickness of 20nm; P-type AlGaN layer 106 has a thickness of 125nm; P-type GaN layer 107 has a thickness of 50nm; In the second step, a positive photoresist layer 112 with a thickness of 500 nm is spin-coated on the P-type GaN layer 107 obtained in the first step. Figure 3 As shown; In the third step, a single-layer SiO2 nanolens layer 113 with a diameter of 20,000 nm is attached to the photoresist layer 112 obtained in the second step. Figure 4 As shown; In the fourth step, an exposure process is performed on the nano lens layer 113 obtained in the third step. The SiO2 nanospheres gather light, so that the part of the nanospheres in contact with the photoresist and the other part of the photoresist have different solubility. Then, a development process is performed to dissolve the part of the nanospheres in contact with the photoresist, and a photoresist nanostructure 114 is produced. In the photoresist nanostructure 114, the diameter of the nanopores is 10000nm. Figure 5 As shown; In the fifth step, an oxide structure 115 is grown in the photoresist nanostructure 114 obtained in the fourth step by magnetron sputtering. Figure 6 As shown; Step 6: The photoresist mask and the oxide on the mask are stripped off by stripping technology to obtain an oxide nanostructure 108 with a diameter of 10000 nm and a thickness of 500 nm. Figure 7 As shown; In the seventh step, a step is made by photolithography and dry etching process, and the oxide nanostructure 108, P-type GaN layer 107, P-type AlGaN layer 106, P-type electron blocking layer 105, multi-quantum well layer 104, and N-type AlGaN layer 103 are etched to form a DUV LED epitaxial layer structure passing through the quantum well structure, and 5% N-type AlGaN layer 103 is exposed. Figure 8 As shown; Step 8: A mask of the P-type ohmic contact layer 109 is made by photolithography technology, so that the mask exposes 100% of the area in the middle of the surface of the P-type GaN layer table 107, and the P-type ohmic contact layer 109 is deposited by electron beam evaporation or magnetron sputtering. The P-type ohmic contact layer 109 is evenly distributed on the surface of the P-type GaN layer 107 and the oxide nanostructure 108. The material of the P-type ohmic contact layer 109 is Ni / Au, and the minimum thickness in the horizontal direction and the minimum thickness in the vertical direction are equal to 20 nm. Then, the mask and the P-type ohmic contact layer 109 on the mask are peeled off; In the ninth step, an N-type ohmic electrode 111 is formed on the exposed N-type AlGaN layer 103 by evaporation and photolithography, with a thickness of 200 nm and an area of ​​80% of the exposed N-type AlGaN layer. Fig. 9 As shown; Step 10: Deposit a metal reflector electrode 110 on the exposed P-type ohmic contact layer 109, which fills the gap between the P-type ohmic contact layers 109 and has a thickness of 200 nm above the P-type ohmic contact layer 109. Fig.10 As shown; Thus, a deep ultraviolet light-emitting diode chip structure with a patterned photon absorption structure is obtained in this embodiment.

[0027] Example 2 The other steps are the same as those in Example 1, except that the material of the oxide nanostructure 108 is replaced by n-type Ga2O3 instead of n-type ZnO.

[0028] The present invention can enhance the hole injection efficiency of the active region and has a significant effect on deep ultraviolet LEDs with unbalanced carrier injection.

[0029] The above embodiment can achieve that the deep ultraviolet LED is combined with the oxide nanostructure, the hole injection capability of the active region is enhanced, and a more balanced carrier concentration is achieved, the radiation recombination of the deep ultraviolet LED is enhanced, the photon recycling is promoted, the photoelectric conversion efficiency is improved, and the luminous efficiency of the overall deep ultraviolet LED is improved, so that more deep ultraviolet light escapes into the air. The method of the present invention has strong operability, simple process, low cost, and is easy to implement.

[0030] The raw materials involved in the present invention can be obtained through known routes, and the operation process in the preparation method thereof can be mastered by those skilled in the art.

[0031] Matters not covered by the present invention are known technologies.

Claims

1. A deep ultraviolet light-emitting diode having a patterned photon absorption structure, characterized in that: The diode comprises a substrate, an AlN buffer layer, and an N-type AlGaN layer from bottom to top; wherein one side of the N-type AlGaN layer is partially exposed; the upper surface of the unexposed portion of the N-type AlGaN layer is sequentially covered with a multi-quantum well layer, a P-type electron blocking layer, a P-type AlGaN layer, and a P-type GaN layer from bottom to top; an array of oxide nanostructures is distributed on the upper surface of the P-type GaN layer; a P-type ohmic contact layer covers the oxide nanostructure and the P-type GaN layer, and also forms an array distribution structure; The metal reflector layer covers the P-type ohmic contact layer; An N-type ohmic electrode is also distributed on the surface of the exposed portion of the N-type AlGaN layer.

2. The deep ultraviolet light emitting diode with a patterned photon absorption structure as claimed in claim 1, characterized in that: The exposed area of ​​the N-type AlGaN layer is 5 to 90% of the surface area of ​​the entire N-type AlGaN layer; the height of the exposed portion is 5 to 90% of the height of the entire N-type AlGaN layer.

3. The deep ultraviolet light emitting diode with a patterned photon absorption structure as claimed in claim 1, characterized in that: The material of the oxide nanostructure is n-type ZnO or n-type Ga2O3, and the doping concentration is 1*10e15-1*10e20 / cm 3 , with a thickness ranging from 5 to 500 nm.

4. The deep ultraviolet light emitting diode with a patterned photon absorption structure as claimed in claim 1, characterized in that: The nanostructure in the oxide nanostructure is a nanocolumn array with a diameter of 10nm-10000nm, a spacing between the nanocolumns of 10nm-10000nm, and a filling rate of 20-80%.

5. The deep ultraviolet light emitting diode with a patterned photon absorption structure as claimed in claim 1, characterized in that: The substrate is a C-plane sapphire substrate; The buffer layer material is AlN, with a thickness of 1~3μm; The material of N-type AlGaN layer is Al 0.6 Ga 0.4 N, thickness is 1~3μm; The structure of the multi-quantum well layer is 5 periods of Al 0.45 Ga 0.55 N / A 0.56 Ga 0.44 N layers, where the quantum barrier Al 0.56 Ga 0.44 The thickness of N is set to 11~12nm, and the quantum well Al 0.45 Ga 0.55 The thickness of N is set to 3~4nm; The P-type electron blocking layer material is Al 0.6 Ga 0.4 N, thickness is 10~50nm; The P-type AlGaN layer material is Al 0.4 Ga 0.6 N, thickness is 50~200nm; The thickness of the P-type GaN layer is 10~50nm; The material of the P-type ohmic contact layer is Ni / Au or Ni / Al; The material of the metal reflector electrode is Al; The material of the N-type ohmic electrode is Cr / Au or Ti / Al / Ti / Au, wherein the projection area of ​​the N-type ohmic electrode is 10-80% of the area of ​​the exposed N-type AlGaN layer.

6. The method for preparing a deep ultraviolet light-emitting diode having a patterned photon absorption structure according to claim 1, characterized in that: The following steps are involved: The first step is to bake the substrate at 1250-1350°C in a MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy) reactor to remove foreign matter on the substrate surface, and then grow an AlN buffer layer, an N-type AlGaN layer, a multi-quantum well layer, a P-type electron blocking layer, a P-type AlGaN layer, and a P-type GaN layer on the sapphire substrate in sequence; In the second step, a positive photoresist layer is spin-coated on the P-type GaN layer obtained in the first step; In the third step, a single layer of nanosphere lens layer is attached to the photoresist layer obtained in the second step; Step 4: on the nanoball lens layer obtained in step 3, a photoresist nanostructure is fabricated by exposure and development process; Step 5, growing an oxide structure in the photoresist nanostructure by magnetron sputtering on the photoresist nanostructure obtained in the step 4; Step 6: stripping the photoresist mask and the oxide on the mask by a stripping technique to obtain an oxide nanostructure; Step 7: The table is made by photolithography and dry etching process, and the oxide nanostructure, P-type GaN layer, P-type AlGaN layer, P-type electron blocking layer, multi-quantum well layer, and N-type AlGaN layer are etched to form a DUV LED epitaxial layer structure that passes through the quantum well structure, and 5-90% of the N-type AlGaN layer is exposed; Step 8: Make a mask for the P-type ohmic contact layer by photolithography technology, so that the mask exposes 30% to 100% of the middle area of ​​the P-GaN table surface, deposit the P-type ohmic contact layer by electron beam evaporation or magnetron sputtering, and then peel off the mask and the P-type ohmic contact layer on the mask; Step 9: evaporate and photolithography an N-type ohmic electrode on the exposed N-type AlGaN layer, with an area of ​​10 to 80% of the area of ​​the exposed N-type AlGaN layer; The tenth step is to evaporate a metal mirror electrode on the exposed P-type ohmic contact layer.

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