Deep ultraviolet LED structure and preparation method thereof

Abstract

The invention relates to the technical field of semiconductors, and discloses a deep ultraviolet LED structure and a preparation method thereof, the deep ultraviolet LED structure comprises an LED substrate, and the LED substrate comprises a substrate, a non-doped AlN buffer layer, a GaN / AlN superlattice layer, an n-type AlGaN layer, an active layer, a p-type AlGaN layer and a p-type GaN cover layer which are stacked in sequence; openings of the plurality of nanoholes are located in the surface of one side, back to the p-type AlGaN layer, of the p-type GaN cover layer, and the nanoholes penetrate through the p-type GaN cover layer, the p-type AlGaN layer and the active layer; the isolating layer is positioned on the inner wall of the nanopore; and the metal nanoparticles are located on the surface of one side, back to the p-type AlGaN layer, of the p-type GaN cover layer and cover the surface of one side, back to the inner wall of the nanopore, of the isolation layer. According to the deep ultraviolet LED structure, the LSPR effect between the metal nanoparticles and the active layer can be enhanced, the light output intensity and effect are improved, and the forward light output intensity and effect of the deep ultraviolet LED structure are improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a deep ultraviolet LED structure and a preparation method thereof. Background Art

[0002] AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) have attracted increasing attention as a highly efficient and portable method for eliminating viruses. However, as the Al content in AlGaN materials increases, the proportion of TM polarized light (transverse magnetic mode) increases, and the emission mode of DUV LEDs gradually shifts from being dominated by TE (transverse electric mode) to being TM-dominated. Due to valence band inversion in high-Al-content AlGaN materials, TM polarization dominates the emission mode, with light propagating parallel to the material's growth axis (c-axis). This means that transversely propagating TM polarized light primarily propagates in the lateral direction, resulting in strong sidewall emission, which in turn reduces device light output and leads to poor forward light extraction capability. However, the traditional flip-chip structure uses a vertical light extraction path (e.g., at the bottom of the device), preventing most lateral light from escaping due to total internal reflection or sidewall absorption, resulting in generally low light extraction efficiency (LEE). Mainstream flip-chip designs rely on a vertical light extraction path (e.g., bottom-out light from a sapphire substrate). Forward light extraction is more compatible with lens packaging, heat dissipation structures, and other factors, reducing the difficulty of industrialization. Furthermore, because AlGaN has a refractive index much higher than that of air or packaging materials, the critical angle for total internal reflection is very small, and most lateral light is reflected back into the material at vertical interfaces. Lateral light primarily emerges from the device sidewalls, but the sidewall surface area of ​​micron-scale chips is much smaller than the front surface, and geometric limitations result in a narrow light extraction channel.

[0003] Surface plasmon properties are extremely helpful in improving the light-emitting performance of optoelectronic devices. Surface plasmons are a collective oscillation phenomenon that occurs when the oscillation frequency of free electrons on the surface of metal nanoparticles matches the frequency of incident photons when a metal is irradiated with incident light of a specific wavelength. Metals capable of producing plasmon effects are limited to certain alkali metals and precious metals, such as Al, Au, Ag, and Rh. These metal nanoparticles generate an electromagnetic field near them that can influence carrier recombination in the active layer, generating a localized surface plasmon resonance effect (LSPR effect), which can enhance light output.

[0004] Therefore, a solution is needed that can utilize the LSPR effect of metal nanoparticles to enhance the light output of the device, while converting the lateral light into the front light, thereby improving the front light intensity and effect of the structure. Summary of the Invention

[0005] In view of this, the present invention provides a deep ultraviolet LED structure and a preparation method thereof to solve the problem in the related art that the light output mode of the deep ultraviolet LED structure of high Al content AlGaN material is mainly TM polarization mode, and the transversely propagating TM polarized light mainly propagates in the transverse direction, resulting in strong sidewall emission, which in turn leads to a reduction in the light output of the device, resulting in poor forward light output capability of the device, and the light output of the device is weak and the effect is poor.

[0006] In a first aspect, the present invention provides a deep ultraviolet LED structure, comprising:

[0007] An LED substrate, comprising a substrate, a non-doped AlN buffer layer, a GaN / AlN superlattice layer, an n-type AlGaN layer, an active layer, a p-type AlGaN layer, and a p-type GaN cap layer stacked in sequence;

[0008] A plurality of nanopores, with openings located on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, and the nanopores penetrating the p-type GaN cap layer, the p-type AlGaN layer, and the active layer;

[0009] an isolation layer, located on the inner wall of the nanopore;

[0010] The metal nanoparticles are located on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, and cover a surface of the isolation layer facing away from the inner wall of the nanopore.

[0011] The deep ultraviolet LED structure provided by the present invention, on the one hand, by setting a nanohole penetrating the p-type GaN cap layer, the p-type AlGaN layer and the active layer, and setting an isolation layer and metal nanoparticles on the inner wall of the nanohole, by controlling the thickness of the isolation layer to make the metal nanoparticles closer to the active layer, so that the distance between the metal nanoparticles and the active layer can meet the conditions of the LSPR effect, thereby maximizing the LSPR effect between the metal nanoparticles and the active layer, generating an electromagnetic field near the metal nanoparticles that can affect the carrier recombination of the active layer, and improving the luminous intensity and light output effect of the structure; at the same time, the nanohole penetrating the active layer can increase The contact area between the metal nanoparticles and the active layer is increased, thereby making the LSPR effect more exciting and further increasing the enhancement effect of the LSPR effect; on the other hand, since the light output mode of the high Al component AlGaN-based deep ultraviolet LED is TM mode (more lateral light output), by covering the metal nanoparticles on the side of the isolation layer facing away from the inner wall of the nanopore, an uneven metal nanoparticle sidewall can be formed in the nanopore, so that the main lateral light output of the deep ultraviolet LED structure can be scattered more to the forward direction of the deep ultraviolet LED structure through the nanoparticles on the uneven sidewall, further improving the forward light output intensity and effect of the structure. Therefore, the deep ultraviolet LED structure provided by the present invention can make the distance between the metal nanoparticles and the active layer meet the conditions of the LSPR effect, can enhance the LSPR effect between the metal nanoparticles and the active layer, improve the intensity and effect of light output, and at the same time increase the contact area between the metal nanoparticles and the active layer, further increasing the enhancement effect of the LSPR effect; it can also enable the main lateral light output of the deep ultraviolet LED structure to be scattered more to the forward direction of the deep ultraviolet LED structure through the nanoparticles with uneven side walls, further improving the forward light output intensity and effect of the deep ultraviolet LED structure.

[0012] In an optional embodiment, the nanohole further penetrates into a partial thickness of the n-type AlGaN layer.

[0013] In the deep ultraviolet LED structure provided by the present invention, the nanopores penetrate into a partial thickness of the n-type AlGaN layer, which can further increase the contact area between the metal nanoparticles and the active layer, enhance the enhancement effect of the LSPR effect, and thus improve the luminous intensity and light output effect of the deep ultraviolet LED structure.

[0014] In an optional embodiment, the material of the metal nanoparticles is Rh or Al;

[0015] The width of the metal nanoparticles is 10nm to 150nm;

[0016] The resonant wavelength of metal nanoparticles is 200nm to 300nm;

[0017] The light emission wavelength of the deep ultraviolet LED structure is 270nm~280nm.

[0018] The deep ultraviolet LED structure provided by the present invention comprises metal nanoparticles made of Rh or Al, with a width of 10 nm to 150 nm. The resonance wavelength of the metal nanoparticles matches the luminescence wavelength of the deep ultraviolet LED structure. Since the size of the metal nanoparticles determines the position of the resonance peak, the closer the position of the resonance peak is to the luminescence wavelength of the deep ultraviolet LED structure, the stronger the LSPR coupling intensity. Therefore, by controlling the width of the metal nanoparticles, the resonance peak position of the metal nanoparticles can be made as close as possible to the luminescence wavelength of the deep ultraviolet LED structure, thereby further enhancing the LSPR effect between the metal nanoparticles and the active layer, and improving the luminescence intensity and light output effect of the deep ultraviolet LED structure.

[0019] In an optional embodiment, the nanopores are arranged in an array;

[0020] The shortest distance between the center lines of two adjacent nanopores is 200nm to 700nm;

[0021] The diameter of the nanopore is 10 nm to 150 nm.

[0022] In an optional embodiment, the material of the substrate is sapphire;

[0023] The thickness of the non-doped AlN buffer layer is 1500nm to 2500nm;

[0024] The thickness of the GaN / AlN superlattice layer is 250nm to 350nm;

[0025] The material of the n-type AlGaN layer is Si-doped n-type Al 0.6 Ga 0.4 N; the thickness of the n-type AlGaN layer is 1300nm to 1500nm;

[0026] The structure of the active layer is five periods of Al 0.37 Ga 0.63 N / A 0.47 Ga 0.53 N quantum well structure; the thickness of the well and barrier in each period is 3nm and 10nm respectively;

[0027] The thickness of the p-type AlGaN layer is 30nm to 50nm;

[0028] The thickness of the p-type GaN cap layer is 10nm to 15nm;

[0029] The material of the isolation layer is SiO2 or Al2O3; the thickness of the isolation layer is 5nm to 15nm.

[0030] The deep ultraviolet LED structure provided by the present invention has an isolation layer with a thickness of 5nm to 15nm. The thickness of the isolation layer can be controlled to bring the metal nanoparticles closer to the active layer, so that the distance between the metal nanoparticles and the active layer can meet the conditions of the LSPR effect, thereby maximizing the LSPR effect between the metal nanoparticles and the active layer.

[0031] In a second aspect, the present invention provides a method for preparing a deep ultraviolet LED structure, which is used to prepare the deep ultraviolet LED structure of the first aspect. The preparation method comprises:

[0032] An LED substrate is provided, which includes a substrate, a non-doped AlN buffer layer, a GaN / AlN superlattice layer, an n-type AlGaN layer, an active layer, a p-type AlGaN layer, and a p-type GaN cap layer stacked in sequence;

[0033] forming a dielectric layer on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer;

[0034] forming a plurality of nanopores on a surface of the dielectric layer facing away from the p-type GaN cap layer, wherein the nanopores penetrate the dielectric layer, the p-type GaN cap layer, the p-type AlGaN layer and the active layer; and then removing the dielectric layer;

[0035] forming an isolation layer on the inner wall of the nanopore;

[0036] Metal nanoparticles are formed on the surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, and the metal nanoparticles also cover the surface of the isolation layer facing away from the inner wall of the nanopore.

[0037] The preparation method of the deep ultraviolet LED structure provided by the present invention comprises the following steps: on the one hand, nanopores are formed to penetrate the dielectric layer, the p-type GaN cap layer, the p-type AlGaN layer and the active layer, and the dielectric layer is removed. The dielectric layer can protect the LED structure from damage during the process of forming the nanopores; and then an isolation layer and metal nanoparticles are formed on the inner wall of the nanopores. The thickness of the isolation layer is controlled to bring the metal nanoparticles closer to the active layer, so that the distance between the metal nanoparticles and the active layer can meet the conditions of the LSPR effect, thereby maximizing the LSPR effect between the metal nanoparticles and the active layer. An electromagnetic field is generated near the nanoparticles, which can affect the carrier recombination in the active layer, thereby improving the luminous intensity and light output effect of the structure; at the same time, the nanopores penetrate the active layer, which can increase the contact area between the metal nanoparticles and the active layer, thereby more strongly exciting the LSPR effect and further increasing the enhancement effect of the LSPR effect; on the other hand, the uneven side walls of the metal nanoparticles are formed in the nanopores, so that the main lateral light output of the deep ultraviolet LED structure can be scattered more to the forward direction of the deep ultraviolet LED structure through the nanoparticles with uneven side walls, further improving the forward light output intensity and effect of the structure.

[0038] In an optional embodiment, the step of forming metal nanoparticles includes:

[0039] forming a metal layer on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, wherein the metal layer also covers a surface of the isolation layer facing away from the inner wall of the nanopore;

[0040] The metal layer is subjected to a thermal annealing process to form metal nanoparticles in the metal layer; the metal nanoparticles are located on the surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, and cover the surface of the isolation layer facing away from the inner wall of the nanopore.

[0041] The preparation method of the deep ultraviolet LED structure provided by the present invention forms a metal layer in the nanopores and forms metal nanoparticles attached to the pore walls through a thermal annealing process. No additional methods are needed to produce the metal nanoparticles. The process method is relatively simple and efficient, which can improve process efficiency and reduce process costs.

[0042] In an optional embodiment, the thickness of the metal layer is 2 nm to 10 nm;

[0043] The temperature of the thermal annealing process is 600°C to 900°C;

[0044] The width of the metal nanoparticles is 10 nm to 150 nm.

[0045] The preparation method of the deep ultraviolet LED structure provided by the present invention controls the thickness of the metal layer to be 2nm to 10nm; the temperature of the thermal annealing process is 600°C to 900°C; and the width of the metal nanoparticles can be controlled to be 10nm to 150nm, so that the resonance peak position of the metal nanoparticles is as close as possible to the emission wavelength of the deep ultraviolet LED structure, thereby further enhancing the LSPR effect between the metal nanoparticles and the active layer, and improving the luminous intensity and light output effect of the deep ultraviolet LED structure.

[0046] In an optional embodiment, the nanopores are arranged in an array;

[0047] The step of forming a plurality of nanopores comprises:

[0048] Provide IPS soft template; IPS soft template includes hole array pattern;

[0049] forming a UV embossing adhesive on a surface of the dielectric layer facing away from the p-type GaN cap layer, wherein the UV embossing adhesive comprises a stacked PMGI adhesive layer and a TU-170 adhesive layer;

[0050] Performing UV soft embossing on the UV embossing adhesive using the IPS soft template, fully curing the UV embossing adhesive after UV exposure, and removing the IPS soft template;

[0051] Removing the residual UV embossing adhesive and transferring the hole array pattern onto the UV embossing adhesive to obtain a patterned UV embossing adhesive;

[0052] Using the patterned UV imprinting adhesive as a mask, etching the dielectric layer, and transferring the hole array pattern onto the dielectric layer to form a patterned dielectric layer;

[0053] Using the patterned dielectric layer as a mask, the p-type GaN cap layer, the p-type AlGaN layer, and the active layer are etched to form a plurality of arrayed nanopores;

[0054] The dielectric layer is then removed using an HF solution.

[0055] The method for fabricating a deep ultraviolet LED structure provided by the present invention first forms a patterned dielectric layer through a nanoimprint process. The patterned dielectric layer is then used as a mask to form a plurality of arrayed nanopores. Compared to traditional etching processes, the nanoimprint process offers the following advantages: First, it offers higher resolution: Nanoimprinting can achieve smaller structure sizes than traditional photolithography, even reaching sub-nanometer resolution. Conventional photolithography resolution is typically limited by the wavelength of the light source, but nanoimprinting utilizes a mold to form nanoscale structures, thus overcoming this limitation. Second, nanoimprinting offers lower costs: Nanoimprinting molds can be reused through a simple imprinting process, significantly reducing manufacturing costs compared to the mask fabrication, exposure, and development steps required in photolithography. Furthermore, nanoimprinting does not rely on expensive laser light sources or complex mask manufacturing processes. Third, nanoimprinting does not require a high-precision alignment system: While some photolithography processes require precise alignment for multi-layer pattern transfer, nanoimprinting typically does not rely on an alignment system. The pattern is transferred directly to the material surface using an imprinting mold, simplifying both equipment and the process.

[0056] In an optional embodiment, the step of forming an isolation layer on the inner wall of the nanopore includes:

[0057] forming an isolation layer on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, wherein the isolation layer also covers the inner wall of the nanopore;

[0058] The isolation layer on the surface of the p-type GaN cap layer is removed by dry etching process, leaving only the isolation layer on the inner wall of the nanopore. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in related technologies, the following briefly introduces the drawings required for use in the specific embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0060] Figure 1 4 is a schematic structural diagram of a deep ultraviolet LED structure according to an embodiment of the present invention.

[0061] Figure 2 Schematic diagram of light scattering within a nanopore of a deep ultraviolet LED structure according to an embodiment of the present invention.

[0062] Figure 3 1 is a flow chart of a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0063] Figure 4 It is a schematic diagram of a specific process of a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0064] Figure 5 3 is a schematic structural diagram of an LED substrate in a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0065] Figure 6 3 is a schematic structural diagram of forming a dielectric layer in a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0066] Figure 7 3 is a schematic structural diagram of forming a UV embossing adhesive in a method for preparing a deep UV LED structure according to an embodiment of the present invention.

[0067] Figure 8 It is a structural schematic diagram of transferring a hole array pattern to a UV embossing adhesive in a method for preparing a deep UV LED structure according to an embodiment of the present invention.

[0068] Figure 9 It is a structural schematic diagram of transferring a hole array pattern to a dielectric layer in a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0069] Figure 10 3 is a schematic structural diagram of forming nanopores in a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0070] Figure 11 3 is a structural schematic diagram of forming an isolation layer in a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0071] Figure 12 3 is a schematic structural diagram of forming a metal layer in a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0072] Figure 13 3 is a schematic structural diagram of forming metal nanoparticles in a method for preparing a deep ultraviolet LED structure according to an embodiment of the present invention.

[0073] Reference numerals:

[0074] 11. Substrate; 12. Undoped AlN buffer layer; 13. GaN / AlN superlattice layer; 14. n-type AlGaN layer; 15. Active layer; 16. p-type AlGaN layer; 17. p-type GaN cap layer; 20. Dielectric layer; 30. Nanopores; 40. Isolation layer; 50. Metal nanoparticles; 60. UV imprint adhesive; 61. PMGI adhesive layer; 62. TU-170 adhesive layer; 70. Metal layer. DETAILED DESCRIPTION

[0075] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0076] In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion about the concepts of the present invention. The accompanying drawings illustrate various schematic diagrams of structures according to embodiments of the present invention. These figures are not drawn to scale; certain details are exaggerated and may be omitted for clarity. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions based on actual needs. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intervening layer / element between them. Furthermore, if a layer / element is "on" another layer / element in one orientation, it may be "below" the other layer / element when the orientation is reversed.

[0077] Deep ultraviolet light in the 200nm to 280nm range can be absorbed by microbial DNA and RNA, disrupting their replication through a series of processes, leading to microbial inactivation. Therefore, deep ultraviolet light-emitting diodes (DUV-LEDs) are widely used in disinfection applications. AlGaN-based DUV-LEDs have garnered increasing attention as an efficient and portable method for eliminating viruses. Furthermore, compared to traditional, toxic mercury lamps, AlGaN-based DUV-LEDs are safer, more reliable, and offer greater development potential. However, as the Al content in AlGaN materials increases, the proportion of TM polarized light increases, gradually shifting the emission mode of deep ultraviolet LEDs from TE-dominant to TM-dominant. Due to valence band inversion, high-Al content AlGaN materials emit predominantly TM polarized light. This light propagates parallel to the material's growth axis (c-axis). This means that transversely propagating TM polarized light primarily propagates in the lateral direction, resulting in strong sidewall emission, which in turn reduces device light output and leads to poor forward light extraction. However, the light extraction path of the traditional flip-chip structure is designed to be in the vertical direction (such as the bottom of the device), resulting in most of the lateral light being unable to escape due to total reflection or sidewall absorption, and the light extraction efficiency (LEE) is generally low. The mainstream flip-chip design relies on the vertical light extraction path (such as the bottom light output of the sapphire substrate). The forward light output is more compatible with lens packaging, heat dissipation structure, etc., reducing the difficulty of industrialization. In addition, because the refractive index of AlGaN is much higher than that of air or packaging materials, the critical angle of total reflection is only very small, and most of the lateral light is reflected back into the material at the vertical interface. The lateral light is mainly emitted from the sidewalls of the device, but the sidewall surface area of ​​the micron-scale chip is much smaller than the front surface, and the geometric limitations lead to a narrow light extraction channel.

[0078] Surface plasmon properties are crucial for improving the light-output performance of optoelectronic devices. Surface plasmons are a collective oscillation phenomenon that occurs when the oscillation frequency of free electrons on the surface of metal nanoparticles matches the frequency of incident photons when irradiated with incident light of a specific wavelength. Metals capable of producing plasmon effects are limited to a select few alkali and precious metals, such as Al, Au, Ag, and Rh. These metal nanoparticles generate an electromagnetic field near them that influences carrier recombination in the active layer, thereby enhancing light output.

[0079] Therefore, a solution is needed that can utilize the LSPR effect of metal nanoparticles to enhance the light output of the device, while converting the lateral light into the front light, thereby improving the front light intensity and effect of the structure.

[0080] like Figure 1 As shown, this embodiment provides a deep ultraviolet LED structure, which includes:

[0081] LED substrate, which includes a substrate 11, an undoped AlN buffer layer 12, a GaN / AlN superlattice layer 13, an n-type AlGaN layer 14, an active layer 15, a p-type AlGaN layer 16, and a p-type GaN cap layer 17 stacked in sequence;

[0082] a plurality of nanopores 30 , the openings of which are located on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16 , and the nanopores 30 penetrate the p-type GaN cap layer 17 , the p-type AlGaN layer 16 , and the active layer 15 ;

[0083] an isolation layer 40 , located on the inner wall of the nanopore 30 ;

[0084] The metal nanoparticles 50 are located on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16 , and cover the surface of the isolation layer 40 facing away from the inner wall of the nanopore 30 .

[0085] In specific implementation, when the distance between the metal nanoparticles 50 and the active layer 15 is close enough, the metal nanoparticles 50 can act as surface plasmons. When the absorption wavelength of the metal nanoparticles 50 matches the emission wavelength of the active layer 15, an LSPR effect will occur between the metal nanoparticles 50 and the active layer 15, which can generate electromagnetic waves that couple with the active layer 15. The coupling mechanism is to generate an electromagnetic field near the metal nanoparticles 50. The presence of the electromagnetic field will increase the recombination of electron-hole pairs in the active layer 15, and the internal quantum efficiency (IQE) of the device will increase, thereby enhancing the luminous intensity of the device. In addition, if Figure 2 As shown, the metal nanoparticles 50 cover the surface of the side of the isolation layer 40 facing away from the inner wall of the nanopore, and can form an uneven metal nanoparticle sidewall in the nanopore 30, so that the main lateral light output of the deep ultraviolet LED structure can be scattered more to the forward direction of the deep ultraviolet LED structure through the uneven nanoparticles on the sidewall, further improving the forward light output intensity and effect of the structure.

[0086] The deep ultraviolet LED structure provided in this embodiment, on the one hand, by setting a nanohole penetrating the p-type GaN cap layer, the p-type AlGaN layer and the active layer, and setting an isolation layer and metal nanoparticles on the inner wall of the nanohole, by controlling the thickness of the isolation layer to make the metal nanoparticles closer to the active layer, so that the distance between the metal nanoparticles and the active layer can meet the conditions of the LSPR effect, thereby maximizing the LSPR effect between the metal nanoparticles and the active layer, generating an electromagnetic field near the metal nanoparticles that can affect the carrier recombination of the active layer, and improving the luminous intensity and light output effect of the structure; at the same time, the nanohole penetrates the active layer, which can The contact area between the metal nanoparticles and the active layer is increased, thereby making the LSPR effect more exciting and further increasing the enhancement effect of the LSPR effect. On the other hand, since the light emission mode of the high Al component AlGaN-based deep ultraviolet LED is the TM mode (more lateral light emission), by covering the metal nanoparticles on the side of the isolation layer facing away from the inner wall of the nanopore, an uneven metal nanoparticle sidewall can be formed in the nanopore, so that the main lateral light output of the deep ultraviolet LED structure can be scattered more to the forward direction of the deep ultraviolet LED structure through the nanoparticles with uneven sidewalls, further improving the forward light output intensity and effect of the structure. Therefore, the deep ultraviolet LED structure provided by the present invention can make the distance between the metal nanoparticles and the active layer meet the conditions of the LSPR effect, can enhance the LSPR effect between the metal nanoparticles and the active layer, improve the light output intensity and effect, and at the same time increase the contact area between the metal nanoparticles and the active layer, further increasing the enhancement effect of the LSPR effect; it can also enable the main lateral light output of the deep ultraviolet LED structure to be scattered more to the forward direction of the deep ultraviolet LED structure through the nanoparticles with uneven side walls, further improving the forward light output intensity and effect of the deep ultraviolet LED structure.

[0087] In some optional embodiments, the nanopore 30 also penetrates into a partial thickness of the n-type AlGaN layer 14 .

[0088] In the deep ultraviolet LED structure provided in this embodiment, the nanopores penetrate into a partial thickness of the n-type AlGaN layer, which can further increase the contact area between the metal nanoparticles and the active layer, increase the enhancement effect of the LSPR effect, and thus improve the luminous intensity and light output effect of the deep ultraviolet LED structure.

[0089] In some optional embodiments, the material of the metal nanoparticles 50 is Rh or Al;

[0090] The width of the metal nanoparticles 50 is 10 nm to 150 nm;

[0091] The resonance wavelength of the metal nanoparticles 50 is 200 nm to 300 nm;

[0092] The light emission wavelength of the deep ultraviolet LED structure is 270nm~280nm.

[0093] In a specific implementation, the emission wavelength of the deep ultraviolet LED structure is the same as the emission wavelength of the active layer. The resonance wavelength of the metal nanoparticles 50 matches the emission wavelength of the active layer, which can produce an LSPR effect.

[0094] In the deep ultraviolet LED structure provided in this embodiment, the material of the metal nanoparticles is Rh or Al, and the width of the metal nanoparticles is 10nm to 150nm; the resonance wavelength of the metal nanoparticles matches the emission wavelength of the deep ultraviolet LED structure. Since the size of the metal nanoparticles determines the position of the resonance peak, the closer the position of the resonance peak is to the emission wavelength of the deep ultraviolet LED structure, the stronger the LSPR coupling intensity. Therefore, by controlling the width of the metal nanoparticles, the resonance peak position of the metal nanoparticles can be made as close as possible to the emission wavelength of the deep ultraviolet LED structure, thereby further enhancing the LSPR effect between the metal nanoparticles and the active layer, and improving the luminous intensity and light output effect of the deep ultraviolet LED structure.

[0095] In some optional embodiments, the material of the metal nanoparticles 50 is Rh;

[0096] The width of the metal nanoparticles 50 is 10 nm to 150 nm;

[0097] The resonant wavelength of the metal nanoparticles 50 is 270 nm to 290 nm;

[0098] The emission wavelength of the deep ultraviolet LED structure is 280nm.

[0099] In some optional embodiments, the nanopores 30 are arranged in an array;

[0100] The shortest distance between the center lines of two adjacent nanopores 30 is 200 nm to 700 nm;

[0101] The diameter of the nanopore 30 is 10 nm to 150 nm.

[0102] The arrayed nanopores 30 include multiple periods, and the period of the nanopores 30 ranges from 200 nm to 700 nm, that is, the shortest distance between the center lines of two adjacent nanopores 30 is 200 nm to 700 nm.

[0103] In some optional embodiments, the material of the substrate 11 is sapphire;

[0104] The thickness of the non-doped AlN buffer layer 12 is 1500 nm to 2500 nm;

[0105] The thickness of the GaN / AlN superlattice layer 13 is 250 nm to 350 nm;

[0106] The material of the n-type AlGaN layer 14 is Si-doped n-type Al 0.6 Ga 0.4 N; the thickness of the n-type AlGaN layer 14 is 1300nm to 1500nm;

[0107] The structure of the active layer 15 is five periods of Al 0.37 Ga 0.63 N / A 0.47 Ga 0.53 N quantum well structure; the thickness of the well and barrier in each period is 3nm and 10nm respectively;

[0108] The thickness of the p-type AlGaN layer 16 is 30 nm to 50 nm;

[0109] The thickness of the p-type GaN cap layer 17 is 10 nm to 15 nm;

[0110] The material of the isolation layer 40 is SiO 2 or Al 2 O 3 ; the thickness of the isolation layer 40 is 5 nm to 15 nm.

[0111] The deep ultraviolet LED structure provided in this embodiment has an isolation layer with a thickness of 5nm to 15nm. The thickness of the isolation layer can be controlled to bring the metal nanoparticles closer to the active layer, so that the distance between the metal nanoparticles and the active layer can meet the conditions of the LSPR effect, thereby maximizing the LSPR effect between the metal nanoparticles and the active layer.

[0112] like Figure 3 As shown, this embodiment provides a method for preparing a deep ultraviolet LED structure, which includes but is not limited to steps S101 to S105.

[0113] Step S101, providing an LED substrate, the LED substrate comprising a substrate 11, an undoped AlN buffer layer 12, a GaN / AlN superlattice layer 13, an n-type AlGaN layer 14, an active layer 15, a p-type AlGaN layer 16, and a p-type GaN cap layer 17 stacked in sequence, as shown in FIG. Figure 5 As shown;

[0114] Step S102: forming a dielectric layer 20 on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16. Figure 6 As shown;

[0115] Step S103, a plurality of nanopores 30 are formed on the surface of the dielectric layer 20 facing away from the p-type GaN cap layer 17, and the nanopores 30 penetrate the dielectric layer 20, the p-type GaN cap layer 17, the p-type AlGaN layer 16 and the active layer 15, as shown in FIG. Figure 10 After that, the dielectric layer 20 is removed, as shown Figure 11 As shown;

[0116] Step S104: forming an isolation layer 40 on the inner wall of the nanopore 30, such as Figure 12 As shown;

[0117] Step S105, forming metal nanoparticles 50 on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16, and the metal nanoparticles 50 also cover the surface of the isolation layer 40 facing away from the inner wall of the nanopore 30, as shown in FIG. Figure 12 shown.

[0118] The preparation method of the deep ultraviolet LED structure provided in this embodiment, on the one hand, forms a nanopore penetrating the dielectric layer, the p-type GaN cap layer, the p-type AlGaN layer and the active layer, and removes the dielectric layer, so that the dielectric layer can protect the LED structure from damage during the process of forming the nanopore; then forms an isolation layer and metal nanoparticles on the inner wall of the nanopore, and controls the thickness of the isolation layer to make the metal nanoparticles closer to the active layer, so that the distance between the metal nanoparticles and the active layer can meet the conditions of the LSPR effect, thereby maximizing the LSPR effect between the metal nanoparticles and the active layer. An electromagnetic field is generated near the metal nanoparticles, which can affect the carrier recombination of the active layer, thereby improving the luminous intensity and light output effect of the structure; at the same time, the nanopores penetrate the active layer, which can increase the contact area between the metal nanoparticles and the active layer, thereby more strongly exciting the LSPR effect and further increasing the enhancement effect of the LSPR effect; on the other hand, the uneven side walls of the metal nanoparticles are formed in the nanopores, so that the main lateral light output of the deep ultraviolet LED structure can be scattered more to the forward direction of the deep ultraviolet LED structure through the nanoparticles with uneven side walls, further improving the forward light output intensity and effect of the structure.

[0119] In some optional embodiments, the nanopores also penetrate into a partial thickness of the n-type AlGaN layer.

[0120] In some optional embodiments, the step of forming the metal nanoparticles 50 includes:

[0121] A metal layer 70 is formed on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16 , and the metal layer 70 also covers the surface of the isolation layer 40 facing away from the inner wall of the nanopore 30 ;

[0122] The metal layer 70 is subjected to a thermal annealing process to form metal nanoparticles 50 in the metal layer 70 ; the metal nanoparticles 50 are located on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16 and cover the surface of the isolation layer 40 facing away from the inner wall of the nanopore 30 .

[0123] The preparation method of the deep ultraviolet LED structure provided in this embodiment forms a metal layer in the nanopore and forms metal nanoparticles attached to the pore wall through a thermal annealing process. No additional methods are required to produce metal nanoparticles. The process method is relatively simple and efficient, which can improve process efficiency and reduce process costs.

[0124] In some optional embodiments, the thickness of the metal layer 70 is 2 nm to 10 nm;

[0125] The temperature of the thermal annealing process is 600°C to 900°C;

[0126] The width of the metal nanoparticles 50 is 10 nm to 150 nm.

[0127] The preparation method of the deep ultraviolet LED structure provided in this embodiment controls the thickness of the metal layer to 2nm~10nm; the temperature of the thermal annealing process is 600℃~900℃; and the width of the metal nanoparticles can be controlled to 10nm~150nm, so that the resonance peak position of the metal nanoparticles is as close as possible to the emission wavelength of the deep ultraviolet LED structure, thereby further enhancing the LSPR effect between the metal nanoparticles and the active layer, and improving the luminous intensity and light output effect of the deep ultraviolet LED structure.

[0128] In some optional embodiments, the nanopores 30 are arranged in an array;

[0129] The step of forming a plurality of nanopores 30 includes:

[0130] Provide IPS soft template; IPS soft template includes hole array pattern;

[0131] A UV embossing adhesive 60 is formed on the surface of the dielectric layer 20 facing away from the p-type GaN cap layer 17 . The UV embossing adhesive 60 includes a stacked PMGI adhesive layer 61 and a TU-170 adhesive layer 62 .

[0132] Performing UV soft embossing on the UV embossing adhesive 60 using the IPS soft template, fully curing the UV embossing adhesive 60 after UV exposure, and removing the IPS soft template;

[0133] Removing the remaining UV embossing adhesive 60 and transferring the hole array pattern onto the UV embossing adhesive 60 to obtain a patterned UV embossing adhesive;

[0134] Using the patterned UV embossing adhesive as a mask, the dielectric layer 20 is etched, and the hole array pattern is transferred onto the dielectric layer 20 to form a patterned dielectric layer;

[0135] Using the patterned dielectric layer as a mask, the p-type GaN cap layer 17, the p-type AlGaN layer 16, and the active layer 15 are etched to form a plurality of arrayed nanopores 30;

[0136] The dielectric layer is then removed using an HF solution.

[0137] The multiple nanopores 30 arranged in an array finally formed penetrate the p-type GaN cap layer, the p-type AlGaN layer and the active layer.

[0138] The method for fabricating a deep ultraviolet LED structure provided in this embodiment first forms a patterned dielectric layer through a nanoimprint process, then uses the patterned dielectric layer as a mask to form a plurality of arrayed nanopores. Compared to traditional etching processes, the nanoimprint process has the following advantages: First, the nanoimprint process has higher resolution: Nanoimprinting can achieve smaller structure sizes than traditional photolithography, even achieving sub-nanometer resolution. The resolution of conventional photolithography is generally limited by the wavelength of the light source, but nanoimprinting uses molds to form nanoscale structures, thus overcoming this limitation. Second, the nanoimprint process has lower cost: Nanoimprinting molds can be reused through a simple imprinting process, significantly reducing manufacturing costs compared to the mask preparation, exposure, and development steps in photolithography. Furthermore, nanoimprinting does not rely on expensive laser light sources and complex mask manufacturing processes. Third, the nanoimprint process does not require a high-precision alignment system: In some photolithography processes, precise alignment is crucial for multi-layer pattern transfer. Nanoimprinting generally does not rely on an alignment system, and the pattern is directly transferred to the material surface through the imprinting mold, simplifying the equipment and process.

[0139] In some optional embodiments, the step of forming the isolation layer 40 on the inner wall of the nanopore 30 includes:

[0140] An isolation layer 40 is formed on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16 , and the isolation layer 40 also covers the inner wall of the nanopore 30 ;

[0141] The isolation layer 40 on the surface of the p-type GaN cap layer 17 is removed by dry etching process, and only the isolation layer 40 on the inner wall of the nanopore 30 is retained.

[0142] In some optional embodiments, the material of the substrate 11 is sapphire;

[0143] The thickness of the non-doped AlN buffer layer 12 is 1500 nm to 2500 nm;

[0144] The thickness of the GaN / AlN superlattice layer 13 is 250 nm to 350 nm;

[0145] The material of the n-type AlGaN layer 14 is Si-doped n-type Al 0.6 Ga 0.4 N; the thickness of the n-type AlGaN layer 14 is 1300nm to 1500nm;

[0146] The structure of the active layer 15 is five periods of Al 0.37 Ga 0.63 N / A 0.47 Ga 0.53 N quantum well structure; the thickness of the well and barrier in each period is 3nm and 10nm respectively;

[0147] The thickness of the p-type AlGaN layer 16 is 30 nm to 50 nm;

[0148] The thickness of the p-type GaN cap layer 17 is 10 nm to 15 nm;

[0149] The material of the dielectric layer 20 is SiO2; the thickness of the dielectric layer 20 is 100nm to 300nm;

[0150] The material of the isolation layer 40 is SiO 2 or Al 2 O 3 ; the thickness of the isolation layer 40 is 5 nm to 15 nm.

[0151] like Figure 4 As shown, the present invention also provides a specific flow diagram of a method for preparing a deep ultraviolet LED structure, comprising the following steps:

[0152] Step S201 , providing an LED substrate, which includes a substrate 11 , an undoped AlN buffer layer 12 , a GaN / AlN superlattice layer 13 , an n-type AlGaN layer 14 , an active layer 15 , a p-type AlGaN layer 16 , and a p-type GaN cap layer 17 stacked in sequence.

[0153] In one example, if Figure 5 As shown, the preparation method of the LED substrate includes: epitaxially growing a non-doped AlN buffer layer with a thickness of 2000nm on the sapphire substrate 11; growing a GaN / AlN superlattice layer 13 with a thickness of 300nm on the non-doped AlN buffer layer; growing a Si-doped n-type Al layer with a thickness of 1400nm on the GaN / AlN superlattice layer 13; and finally growing a Si-doped n-type Al layer with a thickness of 1400nm. 0.6 Ga 0.4 N layer; five periods of Al are grown on the n-type AlGaN layer 14 0.37 Ga 0.63 N / A 0.47 Ga 0.53 An N quantum well structure is formed, with the well and barrier widths being 3nm and 10nm respectively. A p-type AlGaN layer 16 with a thickness of 30nm to 50nm is grown on the quantum well structure (i.e., the active layer 15). A p-GaN cap layer with a thickness of 10nm to 15nm is grown on the p-type AlGaN layer 16.

[0154] Step S202 : forming a dielectric layer 20 on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16 .

[0155] In one example, if Figure 6 As shown, a SiO2 layer with a thickness of 200 nm is grown on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16 by a PECVD process.

[0156] Step S203, providing an IPS soft template; the IPS soft template includes a hole array pattern; forming a UV embossing adhesive 60 on the surface of the dielectric layer 20 facing away from the p-type GaN cap layer 17, the UV embossing adhesive 60 including a stacked PMGI adhesive layer 61 and a TU-170 adhesive layer 62, such as Figure 7 As shown; the UV embossing adhesive 60 is UV soft embossed with an IPS soft template, and the UV embossing adhesive 60 is fully cured after UV exposure, and the IPS soft template is removed; the residual UV embossing adhesive 60 is removed, and the hole array pattern is transferred to the UV embossing adhesive 60, as shown Figure 8 As shown, a patterned UV embossing adhesive is obtained.

[0157] In specific implementations, the steps of providing an IPS soft template include: hot-stamping an IPS composite softened sheet using an original Ni metal template. When selecting a Ni metal template, the size of the periodic nanopores 30 in the hole array pattern is controlled by analyzing the period and duty cycle. The steps of forming a UV embossing adhesive 60 include: sequentially spin-coating a 70nm thick PMGI adhesive and a 200nm thick TU-170 UV embossing adhesive 60 on the surface using a coating machine and baking them, aiming to maximize the exposed sidewall area of ​​the active layer 15. Finally, the sample is UV embossed using the IPS soft template. After UV exposure, the UV embossing adhesive 60 is fully cured, and the IPS soft template is removed, leaving the hole array on the UV embossing adhesive 60. Reactive ion etching is used to transfer the pattern, first removing the residual TU-170 adhesive with oxygen plasma, then removing the PMGI adhesive with a positive photoresist developer, and transferring the hole array pattern to the UV embossing adhesive 60.

[0158] Step S204: Using the patterned UV embossing adhesive as a mask, the dielectric layer 20 is etched to transfer the hole array pattern onto the dielectric layer 20. Figure 9 As shown, a patterned dielectric layer is formed.

[0159] In practice, the dielectric layer 20 is made of silicon dioxide. Using a patterned UV imprinted adhesive as a mask, CHF3 gas is used for ICP etching of the silicon dioxide dielectric layer 20. The hole array pattern is transferred from the imprinted adhesive to the silicon dioxide dielectric layer 20. The TU-170 and PMGI adhesives are then completely removed by ultrasonication using acetone, alcohol, and deionized water for three minutes each. Etching parameters include a CHF3 flow rate of 20 sccm, an Ar flow rate of 5 sccm, an RF power of 40 W, and an ICP power of 230 W.

[0160] Step S205: Using the patterned dielectric layer as a mask, the p-type GaN cap layer 17, the p-type AlGaN layer 16 and the active layer 15 are etched to form a plurality of array-arranged nanopores 30. Figure 10 shown.

[0161] In specific implementation, a patterned silicon dioxide dielectric layer 20 is used as a mask layer, and Cl2 / BCl3 gas is used to etch the p-type GaN cap layer 17, the p-type AlGaN layer 16, and the active layer 15 to form a plurality of nanopores 30. The nanopores 30 penetrate the dielectric layer 20, the p-type GaN cap layer 17, the p-type AlGaN layer 16, and the active layer 15, so that the pattern is transferred to the bottom of the quantum well layer. In this step, the etching depth can be controlled by controlling the etching time. Etching parameters: Cl2 flow rate 18sccm, BCl3 flow rate 25sccm, RF power 25W, ICP power 750W. By etching to the bottom of the active layer 15, the isolation layer 40 and the metal layer can be plated to the side wall of the active layer 15, thereby increasing the contact area between the metal nanoparticles 50 and the active layer 15 after annealing, thereby further enhancing the LSPR effect.

[0162] In one example, during the step of forming the nanohole 30 , a portion of the n-type AlGaN layer 14 is further etched, so that the formed nanohole 30 further penetrates into the portion of the n-type AlGaN layer 14 .

[0163] Step S206, using HF solution to remove the dielectric layer 20, the formed array of nano-holes 30 penetrates the p-type GaN cap layer 17, the p-type AlGaN layer 16 and the active layer 15, as shown in FIG. Figure 11 shown.

[0164] In a specific implementation, a 40% concentration HF solution is used to remove the silicon dioxide dielectric layer 20 .

[0165] In one example, after the dielectric layer is removed, the nanopore 30 further penetrates into a portion of the thickness of the n-type AlGaN layer 14, as shown in FIG. Figure 11 shown.

[0166] Step S207, forming an isolation layer 40 on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16, and the isolation layer 40 also covers the inner wall of the nanopore 30, such as Figure 11 shown.

[0167] In a specific implementation, a PECVD process is used to grow an isolation layer 40 . The material of the isolation layer 40 is SiO 2 or Al 2 O 3 . The thickness of the isolation layer 40 is 5 nm to 15 nm.

[0168] Step S208, using a dry etching process to remove the isolation layer 40 on the surface of the p-type GaN cap layer 17, leaving only the isolation layer 40 on the inner wall of the nanopore 30, such as Figure 12 shown.

[0169] In specific implementation, the ICP dry etching process is used to etch away the top isolation layer 40 and the isolation layer 40 on the surface of the p-type GaN cap layer 17 , leaving only the isolation layer 40 on the inner wall of the nanopore 30 .

[0170] Step S209, forming a metal layer 70 on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16, and the metal layer 70 also covers the surface of the isolation layer 40 facing away from the inner wall of the nanopore 30, as shown in FIG. Figure 12 shown.

[0171] In specific implementations, an electron beam evaporator is used to deposit a metal layer of a predetermined thickness onto the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16. The metal layer 70 also covers the surface of the isolation layer 40 facing away from the inner wall of the nanopore 30. In one example, the metal layer 70 is made of Rh and has a thickness of 2 nm to 10 nm. The thickness of the metal layer determines the size of the metal nanoparticles 50 formed during annealing, and the size of the metal nanoparticles 50 determines the location of the resonance peak. The closer the resonance peak is to the emission wavelength of the final deep ultraviolet LED structure, the stronger the LSPR coupling strength.

[0172] Step S210, performing a thermal annealing process on the metal layer 70 to form metal nanoparticles 50 in the metal layer 70; the metal nanoparticles 50 are located on the surface of the p-type GaN cap layer 17 facing away from the p-type AlGaN layer 16, and cover the surface of the isolation layer 40 facing away from the inner wall of the nanopore 30, as shown in FIG. Figure 13 shown.

[0173] In one example, the metal layer 70 is made of Rh and has a thickness of 2 nm to 10 nm. The thermal annealing process is performed at a temperature of 600°C to 900°C. The width of the metal nanoparticles 50 formed after annealing is 10 nm to 150 nm. The resonant wavelength of the metal nanoparticles 50 is 270 nm to 290 nm. The emission wavelength of the deep ultraviolet LED structure is 280 nm.

[0174] In the description of this specification, the reference terms "this embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in an appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless otherwise clearly defined. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise clearly defined.

[0175] While the above description does not provide detailed technical details regarding patterning and etching of each layer, those skilled in the art will appreciate that various technical means can be employed to form layers, regions, and the like in desired shapes. Furthermore, those skilled in the art may devise methods that differ from those described above to form the same structure. Furthermore, while each embodiment has been described separately, this does not mean that the measures in each embodiment cannot be advantageously combined.

[0176] The above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and that various obvious changes, readjustments, combinations, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of protection of the present invention is determined by the scope of the appended claims.

Claims

1. A deep ultraviolet LED structure, characterized in that: include: An LED substrate, comprising a substrate, a non-doped AlN buffer layer, a GaN / AlN superlattice layer, an n-type AlGaN layer, an active layer, a p-type AlGaN layer, and a p-type GaN cap layer stacked in sequence; a plurality of nanopores, the openings of which are located on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, and the nanopores penetrate the p-type GaN cap layer, the p-type AlGaN layer, and the active layer; an isolation layer, located on the inner wall of the nanopore; The metal nanoparticles are located on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, and cover a surface of the isolation layer facing away from the inner wall of the nanopore.

2. The deep ultraviolet LED structure according to claim 1, characterized in that: The nanopores also penetrate into a portion of the thickness of the n-type AlGaN layer.

3. The deep ultraviolet LED structure according to claim 1, characterized in that: The material of the metal nanoparticles is Rh or Al; The width of the metal nanoparticles is 10nm to 150nm; The resonance wavelength of the metal nanoparticles is 200nm to 300nm; The light emission wavelength of the deep ultraviolet LED structure is 270nm to 280nm.

4. The deep ultraviolet LED structure according to claim 1, characterized in that: The nanopores are arranged in an array; The shortest distance between the center lines of two adjacent nanopores is 200 nm to 700 nm; The diameter of the nanopore is 10 nm to 150 nm.

5. The deep ultraviolet LED structure according to claim 1, characterized in that: The material of the substrate is sapphire; The thickness of the non-doped AlN buffer layer is 1500nm to 2500nm; The thickness of the GaN / AlN superlattice layer is 250nm to 350nm; The material of the n-type AlGaN layer is Si-doped n-type Al 0.6 Ga 0.4 N; the thickness of the n-type AlGaN layer is 1300nm to 1500nm; The structure of the active layer is five periods of Al 0.37 Ga 0.63 N / A 0.47 Ga 0.53 N quantum well structure; the thickness of the well and barrier in each period is 3nm and 10nm respectively; The thickness of the p-type AlGaN layer is 30nm to 50nm; The thickness of the p-type GaN cap layer is 10nm to 15nm; The material of the isolation layer is SiO2 or Al2O3; the thickness of the isolation layer is 5nm to 15nm.

6. A method for preparing a deep ultraviolet LED structure, for preparing the deep ultraviolet LED structure according to claim 1, characterized in that: include: An LED substrate is provided, wherein the LED substrate comprises a substrate, an undoped AlN buffer layer, a GaN / AlN superlattice layer, an n-type AlGaN layer, an active layer, a p-type AlGaN layer, and a p-type GaN cap layer stacked in sequence; forming a dielectric layer on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer; forming a plurality of nanopores on a surface of the dielectric layer facing away from the p-type GaN cap layer, wherein the nanopores penetrate the dielectric layer, the p-type GaN cap layer, the p-type AlGaN layer and the active layer; then removing the dielectric layer; forming an isolation layer on the inner wall of the nanopore; Metal nanoparticles are formed on the surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, and the metal nanoparticles also cover the surface of the isolation layer facing away from the inner wall of the nanopore.

7. The method for preparing a deep ultraviolet LED structure according to claim 6, wherein: The step of forming metal nanoparticles comprises: forming a metal layer on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, wherein the metal layer also covers a surface of the isolation layer facing away from the inner wall of the nanopore; The metal layer is subjected to a thermal annealing process to form metal nanoparticles in the metal layer; the metal nanoparticles are located on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, and cover a surface of the isolation layer facing away from the inner wall of the nanopore.

8. The method for preparing a deep ultraviolet LED structure according to claim 7, wherein: The thickness of the metal layer is 2nm to 10nm; The temperature of the thermal annealing process is 600°C to 900°C; The width of the metal nanoparticles is 10 nm to 150 nm.

9. The method for preparing a deep ultraviolet LED structure according to claim 6, wherein: The nanopores are arranged in an array; The step of forming a plurality of nanopores comprises: Providing an IPS soft template; the IPS soft template includes a hole array pattern; forming a UV embossing adhesive on a surface of the dielectric layer facing away from the p-type GaN cap layer, wherein the UV embossing adhesive comprises a stacked PMGI adhesive layer and a TU-170 adhesive layer; Performing ultraviolet soft embossing on the ultraviolet embossing adhesive using the IPS soft template, fully curing the ultraviolet embossing adhesive after ultraviolet exposure, and removing the IPS soft template; Removing the remaining UV embossing adhesive, and transferring the hole array pattern onto the UV embossing adhesive to obtain a patterned UV embossing adhesive; Using the patterned UV embossing adhesive as a mask, etching the dielectric layer, and transferring the hole array pattern onto the dielectric layer to form a patterned dielectric layer; Using the patterned dielectric layer as a mask, etching the p-type GaN cap layer, the p-type AlGaN layer, and the active layer to form a plurality of arrayed nanopores; The dielectric layer is then removed using an HF solution.

10. The method for preparing a deep ultraviolet LED structure according to claim 6, wherein: The step of forming an isolation layer on the inner wall of the nanopore comprises: forming an isolation layer on a surface of the p-type GaN cap layer facing away from the p-type AlGaN layer, wherein the isolation layer also covers an inner wall of the nanopore; The isolation layer on the surface of the p-type GaN cap layer is removed by a dry etching process, and only the isolation layer on the inner wall of the nanopore is retained.

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