Light emitting diode and light emitting device

Abstract

The invention provides a light-emitting diode and a light-emitting device, and the light-emitting diode comprises a substrate, an epitaxial structure, a first electrode, a first reflection layer, and a second reflection layer. The substrate is provided with a substrate front face and a substrate back face which are oppositely arranged, and the extending direction perpendicular to the substrate front face is the axial direction. The epitaxial structure is formed on one side of the front face of the substrate and comprises a first semiconductor layer, an active layer and a second semiconductor layer which are sequentially stacked from the front face of the substrate. The first electrode is located above the second semiconductor layer and is conductively connected with the second semiconductor layer, the first reflecting layer is arranged between the first electrode and the second semiconductor layer, the second reflecting layer is arranged between the first semiconductor layer and the substrate, and at least the surface of the corresponding second reflecting layer below the first electrode is arranged to be of a slope-shaped structure with an inclined wall surface. According to the technical scheme, the light extraction efficiency is optimized, and light loss caused by electrode shielding is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices and apparatuses, and in particular to a light emitting diode and a light emitting apparatus. Background Art

[0002] As the AR / VR (augmented reality technology / virtual reality technology) market gradually expands, the demand for Micro LED (micro light emitting diode) applications in AR / VR is also growing. In the process of pursuing smaller and lighter applications, the size requirements of Micro LED are also gradually decreasing.

[0003] Micro LED products have high requirements on chip size in AR / VR applications. The chip size is often 5um, 2um, or even below 2um. In order to meet the needs of chip miniaturization as much as possible, the packaging structure of Micro LED products generally adopts a vertical structure. In the vertical chip structure, the main light-emitting direction is generally called the axial direction (that is, the direction from the back to the front of the epitaxial structure). The axial light-emitting surface is provided with an electrode structure. The electrode structure of the light-emitting surface will block part of the light-emitting surface, affecting the luminous brightness of the product to a certain extent. Especially when the chip size is below 2um, the size of the light-emitting surface will also be reduced. At this time, the electrode structure of the light-emitting surface almost completely blocks the entire light-emitting surface, seriously affecting the luminous brightness of the product. Summary of the invention

[0004] The purpose of the present application is to provide a light emitting diode and a light emitting device, which optimize the light extraction efficiency and reduce the light loss caused by electrode shading.

[0005] In the first aspect, the present application provides a light-emitting diode, comprising a substrate, an epitaxial structure, a first electrode, a first reflective layer, and a second reflective layer. The substrate has a substrate front side and a substrate back side arranged opposite to each other, and the extension direction perpendicular to the substrate front side is called an axial direction. The epitaxial structure is formed on the front side of the substrate, and the epitaxial structure comprises a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the front side of the substrate. The first electrode is located above the second semiconductor layer and is conductively connected to the second semiconductor layer, the first reflective layer is arranged between the first electrode and the second semiconductor layer, the second reflective layer is arranged between the first semiconductor layer and the substrate, and at least the surface of the second reflective layer corresponding to the lower side of the first electrode is arranged to be a sloped structure with an inclined wall surface.

[0006] In a second aspect, the present application provides a light-emitting device, comprising a circuit substrate and at least one light-emitting diode fixed to a surface of the circuit substrate, wherein the light-emitting diode is the light-emitting diode described above.

[0007] Compared with the prior art, the beneficial effects of this application include at least:

[0008] The light-emitting diode of the present application is designed to optimize the light extraction efficiency and reduce the light loss caused by electrode shielding. Specifically, when the light-emitting diode generates light in the working state, part of the light will be emitted toward the bottom side of the first electrode. These light rays are effectively reflected downward by the first reflective layer and then reach the second reflective layer. The second reflective layer is specially designed with a sloped structure, which not only receives the light reflected by the first reflective layer, but also further reflects the light through its inclined wall design and guides it to the side wall direction of the epitaxial structure. This design allows part or all of the light that may have been blocked by the first electrode to be exported through the side wall of the epitaxial structure, thereby significantly reducing the shielding effect of the first electrode on the front light of the light-emitting diode, ensuring the brightness and efficiency of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 A cross-sectional view of a first light emitting diode shown in an embodiment of the present application;

[0011] Figure 2 A cross-sectional view of a second light emitting diode shown in an embodiment of the present application;

[0012] Figure 3 A cross-sectional view of a third light emitting diode shown in an embodiment of the present application;

[0013] Figure 4 A cross-sectional view of a fourth light emitting diode shown in an embodiment of the present application;

[0014] Figure 5 A cross-sectional view of a light emitting diode with a roughened structure shown in an embodiment of the present application;

[0015] Figure 6 A cross-sectional view of a light emitting diode with a lens structure shown in an embodiment of the present application;

[0016] Figure 7 A cross-sectional view of a light emitting diode with an asymmetric slope structure shown in an embodiment of the present application;

[0017] Figure 8 A cross-sectional view of a light emitting diode having a large arc-shaped slope structure shown in an embodiment of the present application;

[0018] Fig. 9A cross-sectional view of a light emitting diode having a small arc-shaped slope structure shown in an embodiment of the present application;

[0019] Fig.10 A cross-sectional view of a light emitting diode having a trapezoidal slope structure shown in an embodiment of the present application;

[0020] Fig.11 A cross-sectional view of a light emitting diode having a pointed cone-shaped slope structure shown in an embodiment of the present application;

[0021] Fig.12 The cross-sectional view of the slope-shaped structure shown in the embodiment of the present application having a plurality of pointed conical protrusion structures;

[0022] Fig.13 A cross-sectional view of a slope-shaped structure having a plurality of arc-shaped protruding structures shown in an embodiment of the present application;

[0023] Fig.14 A cross-sectional view of a slope-shaped structure having a plurality of protruding structures of mixed shapes shown in an embodiment of the present application;

[0024] Fig.15 A cross-sectional view of a light-emitting diode having a first reflective layer with an inclined structure shown in an embodiment of the present application;

[0025] Fig.16 This is a structural diagram of a light-emitting device shown in an embodiment of the present application.

[0026] In the figure: 100, light-emitting diode; 1, substrate; 2, epitaxial structure; 21, first semiconductor layer; 22, active layer; 23, second semiconductor layer; 24, roughened structure; 3, first electrode; 4, first reflective layer; 41, inclined structure; 5, second reflective layer; 51, sloped structure; 511, raised structure; 6, lens; 7, transparent encapsulation layer; 8, second electrode; 200, circuit substrate. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0029] In order to meet the needs of chip miniaturization as much as possible, the chip size of Micro LED products is often 5um, 2um, or even below 2um. In Micro LED products with chip miniaturization, the electrode structure on the light-emitting surface will block 50% or even more of the light-emitting surface, especially for chips below 2um, where the electrode structure almost blocks the entire light-emitting surface, seriously affecting the luminous brightness of the product. In order to solve this problem, the following technical solution is provided.

[0030] The present application provides a light-emitting diode, including a substrate, an epitaxial structure, a first electrode, a first reflective layer, and a second reflective layer. The substrate has a substrate front side and a substrate back side arranged opposite to each other, and the extension direction perpendicular to the substrate front side is called an axial direction. The epitaxial structure is formed on the front side of the substrate, and the epitaxial structure includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the front side of the substrate. The first electrode is located above the second semiconductor layer and is conductively connected to the second semiconductor layer. The first reflective layer is arranged between the first electrode and the second semiconductor layer. The second reflective layer is arranged between the first semiconductor layer and the substrate, and at least the surface of the second reflective layer corresponding to the lower side of the first electrode is arranged to be a sloped structure with an inclined wall surface.

[0031] The light-emitting diode of the present application is designed to optimize the light extraction efficiency and reduce the light loss caused by electrode shielding. Specifically, when the light-emitting diode generates light in the working state, part of the light will be emitted toward the bottom side of the first electrode. These light rays are effectively reflected downward by the first reflective layer and then reach the second reflective layer. The second reflective layer is specially designed with a sloped structure, which not only receives the light reflected by the first reflective layer, but also further reflects the light through its inclined wall design and guides it to the side wall direction of the epitaxial structure. This design allows part or all of the light that may have been blocked by the first electrode to be exported through the side wall of the epitaxial structure, thereby significantly reducing the shielding effect of the first electrode on the front light of the light-emitting diode, ensuring the brightness and efficiency of the light-emitting diode.

[0032] In an optional solution, the first semiconductor layer of the epitaxial structure is an N-type semiconductor layer, the second semiconductor layer is a P-type semiconductor layer, and the N-type semiconductor layer, the active layer, and the P-type semiconductor layer can all be GaN-based or AlGaInP-based materials. The epitaxial structure can be prepared by chemical vapor deposition.

[0033] In an optional solution, the first reflective layer and the second reflective layer can be a DBR reflective structure or an ODR reflective structure. DBR (Distributed Bragg Reflector) and ODR (Omni-Directional Reflector) are two different reflective structures, which play a role in enhancing light reflection and improving light extraction efficiency in LED structures.

[0034] The ODR reflective structure is based on the waveguide effect of light and the principle of total reflection. It realizes the transmission and reflection of light by multiple reflections inside the mirror. ODR is generally composed of two parallel reflective surfaces, one of which is partially coated to form a high reflectivity, and the other is fully reflective. When light enters from the partially coated reflective surface, the light beam can be reflected multiple times by the partially coated reflective surface according to the size of the incident angle. During these reflections, the transmission direction of the light will change, but the total energy remains inside the mirror. When the incident angle reaches a certain condition, it exceeds the critical angle, and the light can no longer be transmitted from the partially coated surface, and total reflection occurs. At this time, the light will reflect back and forth multiple times between the partially coated reflective surface and the fully reflective surface, and remain transmitted inside the mirror. ODR can reflect a light beam from one position to another, realizing the transmission and reflection of light.

[0035] The DBR reflective structure is a reflector formed by stacking thin films of different refractive indices alternately and periodically. When light passes through these thin films of different refractive indices, the light reflected from each layer undergoes constructive interference due to the change in phase angle, and then combines with each other to obtain strong reflected light. The DBR reflectivity is determined by the refractive index difference of each layer of material that makes up the DBR and the number of DBR cycles.

[0036] In general, ODR and DBR each have unique advantages and applicable scenarios. ODR, with its omnidirectional reflection capability, is suitable for applications that require wide coverage and beam control, while DBR, with its high reflectivity and wavelength selectivity, is suitable for applications that require specific wavelength reflection and laser stability. According to different design requirements and application needs, technicians in this field can select the appropriate reflection structure.

[0037] In an optional solution, the projection boundary of the first electrode onto the front surface of the first reflective layer may completely coincide with the front area boundary of the first reflective layer, or the projection boundary of the first electrode onto the front surface of the first reflective layer may be located within the front area boundary of the first reflective layer.

[0038] For example, for a light-emitting diode with a chip size of more than 2um, the size of the first electrode may be smaller than the size of the second semiconductor layer, that is, the first electrode cannot completely block the second semiconductor layer. In this case, the first reflective layer can completely cover the front of the second semiconductor layer, or cover part of the front of the second semiconductor layer, but the front area of ​​the first reflective layer must at least include the blocking area of ​​the first electrode. For another example, for a light-emitting diode with a chip size of less than 2um, the size of the first electrode may be substantially equal to the size of the second semiconductor layer, that is, the first electrode substantially completely blocks the second semiconductor layer. In this case, the first reflective layer is configured to completely cover the front of the second semiconductor layer to completely include the blocking area of ​​the first electrode.

[0039] In an alternative solution, the first reflective layer completely covers the surface of the second semiconductor layer so that the light is all guided out from the side surfaces of the epitaxial structure.

[0040] The light emitting diode of the present application comprises a second electrode formed on the back side of the substrate and conductively connected to the first semiconductor layer.

[0041] In an optional solution, the epitaxial structure has an inclined side wall. For example, the angle β of the side wall of the epitaxial structure relative to the back of the epitaxial structure can be in the range of 30° to 70°, which increases the chance of light escaping from the epitaxial structure, reduces the propagation path of light in the epitaxial structure to a certain extent, reduces the absorption of light by the material, and improves the light output efficiency.

[0042] In an optional solution, the sidewall of the epitaxial structure is provided with a roughened structure, the height difference range of the roughened structure can be set to 0.1 to 0.5 um, and the roughened structure can be a regular patterned structure or an irregular patterned structure. In addition, the roughened structure can be passivated after being manufactured. The roughened structure improves the light extraction efficiency inside the vertical structure chip.

[0043] The light-emitting diode of the present application includes a transparent encapsulation layer, which at least covers the surface of the epitaxial structure. Among them, the transparent encapsulation layer can be a multi-layer stacked structure, for example, it can include an anti-reflection film layer and a protective film layer stacked in sequence. The transparent encapsulation layer can play the role of anti-reflection and protection. The transparent encapsulation layer (especially the anti-reflection film layer) mainly increases the intensity of the emitted light by reducing the reflection of light at the interface between the chip and the air, thereby improving the light extraction efficiency. The transparent encapsulation layer (especially the protective film layer) can provide mechanical protection for the chip, prevent the chip from being exposed to the air for a long time or mechanically damaged, and improve the stability and reliability of the chip.

[0044] In an optional solution, the projection boundary of the first electrode onto the front surface of the substrate may exceed the projection boundary of the slope structure onto the front surface of the substrate. That is, after the light vertically incident on one side of the bottom surface of the first electrode is reflected back by the first reflective layer, only a portion of the reflected light is received by the slope structure and reflected toward the side wall direction of the epitaxial structure, so as to reduce light loss and improve luminous brightness and luminous efficiency.

[0045] In an optional solution, the projection boundary of the first electrode onto the front surface of the substrate does not exceed the projection boundary of the slope structure onto the front surface of the substrate. In this way, after the light vertically incident on the bottom surface of the first electrode is reflected back by the first reflective layer, all the reflected light can be received by the slope structure as much as possible and reflected toward the side wall direction of the epitaxial structure, so as to reduce light loss and significantly improve the luminous brightness and luminous efficiency.

[0046] In an optional solution, the sloped structure may be an asymmetric structure. The inclined wall surface of the sloped structure below the first electrode may be inclined toward the same side, so as to reflect most of the light to the single side wall of the epitaxial structure, thereby improving the luminous brightness of the single side wall.

[0047] In an optional solution, the center position of the overall sloped structure coincides with the center position of the first electrode in the axial direction, and the overall sloped structure is symmetrical about its own center position. At the same time, the center position of the first electrode coincides with the center position of the epitaxial structure in the axial direction, thereby making the amount of light reflected by the sloped structure to the side walls on both sides of the epitaxial structure basically the same, so that the luminous brightness of the side walls of the epitaxial structure is basically the same.

[0048] In an optional solution, the sloped structure includes at least one convex structure, and the convex structure is provided with an inclined side wall for reflecting light.

[0049] In an optional solution, the surface shape of the inclined sidewall of the protruding structure can be a plane, an arc surface or a combination of the two. For example, the cross-sectional shape of the protruding structure can be a triangle, a pointed cone, a trapezoid, an arc, etc.

[0050] In an alternative solution, the protruding structure may be an asymmetric structure.

[0051] In an optional solution, the protruding structures may be symmetrical structures, that is, each protruding structure has inclined side walls that are symmetrically arranged about its own center position.

[0052] In an optional solution, the slope structure includes a plurality of protruding structures, and the plurality of protruding structures are distributed in an array along the back side of the epitaxial structure. The inclined wall surfaces of the plurality of protruding structures can receive as much light reflected from the first reflective layer at multiple angles as possible, thereby reducing brightness loss.

[0053] In an optional solution, the height difference between the top and the root of the protrusion structure ranges from 0.2 to 1 um.

[0054] In an optional solution, the light-emitting diode also includes a lens, which covers the front side and at least part of the side wall of the epitaxial structure, and is used to guide part of the light emitted from the epitaxial structure in the axial direction. The "partial light" here mainly refers to the large-angle light emitted from the side of the epitaxial structure, which seriously deviates from the axial direction. The lens is used to guide the large-angle light as much as possible in the axial direction. It should be noted that the "guiding axial direction" here does not necessarily mean completely coinciding with the axial direction, but refers to reducing the angle between the direction of light emission and the axial direction. It may coincide or there may be a certain angle.

[0055] In an optional solution, at least the back side of the first reflective layer corresponding to the first electrode is provided with an inclined structure. When the light in the epitaxial structure is directed vertically or obliquely toward the bottom of the first electrode, it will be directed toward the inclined structure of the first reflective layer, and the inclined structure will reflect the light. Since the inclined structure has an inclined surface, the light directed vertically toward the bottom surface of the first electrode will be directed toward the surface of the second reflective layer in an inclined manner by the inclined surface of the inclined structure, and the second reflective layer will further guide the light toward the side wall direction of the epitaxial structure.

[0056] In an optional solution, the inclined structure of the first reflective layer can be the same as or similar to the sloped structure of the second reflective layer. At the same time, the inclined structure can be arranged to be symmetrical about the axial center line where the center position of the first electrode is located.

[0057] The present application also provides a light-emitting device, comprising a circuit substrate and at least one light-emitting diode fixed to the surface of the circuit substrate, wherein the light-emitting diode is the light-emitting diode in the aforementioned solution.

[0058] In order to explain the light emitting diode of the present application in more detail, the following embodiments are provided for illustration. It should be noted that the technical features and technical solutions in the following embodiments can be used in combination with each other without conflict.

[0059] Embodiment 1

[0060] like Figure 1 As shown, this embodiment provides a light emitting diode, including a substrate 1, an epitaxial structure 2, a first electrode 3, a first reflective layer 4, and a second reflective layer 5.

[0061] The substrate 1 has a substrate front side and a substrate back side which are arranged opposite to each other, and the extension direction perpendicular to the substrate front side is called the axial direction. The epitaxial structure 2 is formed on the side of the substrate front side, and the epitaxial structure 2 includes a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23 which are stacked in sequence from the substrate front side. The first electrode 3 is located above the second semiconductor layer 23 and is conductively connected to the second semiconductor layer 23. The first reflective layer 4 is arranged between the first electrode 3 and the second semiconductor layer 23. The second reflective layer 5 is arranged between the first semiconductor layer 21 and the substrate 1, and at least the surface of the second reflective layer 5 corresponding to the lower side of the first electrode 3 is arranged as a slope structure 51 with an inclined wall surface.

[0062] The light emitting diode of this embodiment includes a second electrode 8 formed on the back side of the substrate 1 and conductively connected to the first semiconductor layer 21. It should be noted that the specific conductive connection position between the second electrode 8 and the first semiconductor layer 21 is not shown in the drawings.

[0063] The light-emitting diode of this embodiment includes a transparent encapsulation layer 7, which at least covers the surface of the epitaxial structure 2. The transparent encapsulation layer 7 can be a multi-layer stacked structure, for example, it can include an anti-reflection film layer and a protective film layer stacked in sequence. The transparent encapsulation layer 7 can play the role of anti-reflection and protection. The transparent encapsulation layer 7 (especially the anti-reflection film layer) mainly increases the intensity of the emitted light by reducing the reflection of light at the interface between the chip and the air, thereby improving the light extraction efficiency. The transparent encapsulation layer 7 (especially the protective film layer) can provide mechanical protection for the chip, prevent the chip from being exposed to the air for a long time or being mechanically damaged, and improve the stability and reliability of the chip.

[0064] It should be noted that see Figure 4 The light emitting diode of this embodiment may include a substrate 1 and a plurality of mutually independent epitaxial structures 2 formed on the same substrate 1 .

[0065] The light-emitting diode of this embodiment is designed to optimize the light extraction efficiency and reduce the light loss caused by electrode shielding. Specifically, when the light-emitting diode generates light in the working state, part of the light will be emitted toward the bottom side of the first electrode 3. These light rays are effectively reflected downward by the first reflective layer 4 and then reach the second reflective layer 5. The second reflective layer 5 is specially designed with a slope structure 51, which not only receives the light reflected by the first reflective layer 4, but also further reflects the light through its inclined wall design and guides it to the side wall direction of the epitaxial structure 2. This design allows part or all of the light that may have been blocked by the first electrode 3 to be exported through the side wall of the epitaxial structure 2, thereby significantly reducing the shielding effect of the first electrode 3 on the front light of the light-emitting diode, ensuring the brightness and efficiency of the light-emitting diode.

[0066] In this embodiment, the first semiconductor layer 21 of the epitaxial structure 2 can be an N-type semiconductor layer, the second semiconductor layer 23 can be a P-type semiconductor layer, and the N-type semiconductor layer, the active layer 22, and the P-type semiconductor layer are all GaN-based materials. The epitaxial structure 2 can be prepared by chemical vapor deposition.

[0067] In this embodiment, the first reflective layer 4 and the second reflective layer 5 can be a DBR reflective structure or an OBR reflective structure. DBR (Distributed Bragg Reflector) and OBR (Organic Bragg Reflector) are two different reflective structures, which play a role in enhancing light reflection and improving light extraction efficiency in the LED structure. Those skilled in the art can reasonably determine the type of reflective structure selected according to actual needs and the characteristics of the reflective structure.

[0068] In this embodiment, if Figures 1 to 3 As shown, the projection boundary of the first electrode 3 onto the front surface of the first reflective layer 4 may completely coincide with the front area boundary of the first reflective layer 4 , or the projection boundary of the first electrode 3 onto the front surface of the first reflective layer 4 may be located within the front area boundary of the first reflective layer 4 .

[0069] For example, for LEDs with chip sizes larger than 2 μm, see Figure 1 and Figure 2 , the size of the first electrode 3 may be smaller than the size of the second semiconductor layer 23, that is, the first electrode 3 cannot completely block the second semiconductor layer 23. In this case, the first reflective layer 4 can completely cover the front of the second semiconductor layer 23, or cover part of the front of the second semiconductor layer 23, but the front area of ​​the first reflective layer 4 must at least include the blocking area of ​​the first electrode 3. For another example, for a light-emitting diode with a chip size of less than 2um, see Figure 3 , the size of the first electrode 3 may be substantially equal to the size of the second semiconductor layer 23 , that is, the first electrode 3 substantially completely blocks the second semiconductor layer 23 . At this time, the first reflective layer 4 is configured to completely cover the front surface of the second semiconductor layer 23 to completely include the blocking area of ​​the first electrode 3 .

[0070] In this embodiment, the first reflective layer 4 may be arranged to completely cover the surface of the second semiconductor layer 23 , so that the light is all guided out from the side of the epitaxial structure 2 .

[0071] In this embodiment, if Figure 3As shown, the projection boundary of the first electrode 3 to the front of the substrate can exceed the projection boundary of the slope structure 51 to the front of the substrate. That is, after the light vertically irradiated to one side of the bottom surface of the first electrode 3 is reflected back by the first reflective layer 4, only part of the reflected light is received by the slope structure 51 and reflected to the side wall direction of the epitaxial structure 2, which can reduce light loss to a certain extent and improve luminous brightness and luminous efficiency.

[0072] In this embodiment, if Figure 1 , Figure 2 and Figures 7 to 14 As shown, it is preferred that the projection boundary of the first electrode 3 to the front of the substrate does not exceed the projection boundary of the slope structure 51 to the front of the substrate. In this way, after the light vertically incident on the bottom surface of the first electrode 3 is reflected back by the first reflective layer 4, all the reflected light can be received by the slope structure 51 as much as possible and reflected to the side wall direction of the epitaxial structure 2, so as to greatly reduce the light loss and significantly improve the luminous brightness and luminous efficiency.

[0073] In this embodiment, if Figure 7 As shown, the slope structure 51 may be an asymmetric structure. The inclined wall surface of the slope structure 51 located below the first electrode 3 may be inclined toward the same side, so as to reflect most of the light to the single side wall of the epitaxial structure 2, thereby improving the luminous brightness of the single side wall.

[0074] In this embodiment, if Figures 8 to 14 As shown, the center position of the sloped structure 51 as a whole preferably coincides with the center position of the first electrode 3 in the axial direction, and the sloped structure 51 as a whole is symmetrical about its own center position. At the same time, the center position of the first electrode 3 coincides with the center position of the epitaxial structure 2 in the axial direction, which can make the amount of light reflected by the sloped structure to the side walls on both sides of the epitaxial structure basically the same, so that the luminous brightness of the side walls of the epitaxial structure is basically the same.

[0075] In this embodiment, if Figures 7 to 14 As shown, the slope structure 51 includes at least one protruding structure 511, and the protruding structure 511 is provided with an inclined side wall for reflecting light. Figures 7 to 11 The slope structure 51 shown has only one protruding structure 511. Figure 12 to Figure 14 The sloped structure 51 shown has a plurality of protruding structures 511 .

[0076] In this embodiment, if Figures 7 to 11 As shown, the surface shape of the inclined side wall of the protrusion structure 511 can be a plane, an arc surface or a combination of the two. The cross-sectional shape of the protrusion structure can be a triangle ( Figure 7 ), pointed conical ( Fig.11 ), Trapezoid( Fig.10 ), arc shape( Figure 8 and Fig. 9 )wait.

[0077] In this embodiment, the protrusion structure 511 may be an asymmetric structure. Figure 7 As shown, the protruding structure 511 is triangular, but the inclination and side length of the side walls on both sides are also different, so as to achieve differentiated light reflection capabilities on both sides.

[0078] In this embodiment, the protrusion structure 511 may be a symmetrical structure. Figures 8 to 11 As shown, preferably each protruding structure 511 has an inclined side wall that is symmetrically arranged about its own center position.

[0079] In this embodiment, if Figures 8 to 14 As shown, the slope structure 51 includes a plurality of protruding structures 511, which are distributed in an array along the back of the epitaxial structure 2. The inclined wall surfaces of the plurality of protruding structures 511 can receive as much light reflected from the first reflective layer 4 at multiple angles as possible, thereby reducing brightness loss.

[0080] Meanwhile, in this embodiment, if Figures 8 to 14 As shown, the center position of the sloped structure 51 as a whole coincides with the center position of the first electrode 3 in the axial direction. The sloped structure 51 as a whole is symmetrical about its own center position, and together with the multiple array-arranged protrusion structures 511 it includes, it can further improve the light reflection efficiency and improve the luminous brightness and brightness uniformity of the two side walls of the epitaxial structure 2.

[0081] In this embodiment, the slope structure 51 may include a plurality of protrusion structures 511 with the same structure. Fig.12 As shown, the slope structure 51 includes a plurality of protruding structures 511 in a pointed cone shape. Fig.13 As shown, the slope structure 51 includes a plurality of arc-shaped protruding structures 511 .

[0082] In this embodiment, the slope structure 51 may include a plurality of protrusion structures 511 with different structures. Fig.14 As shown, the slope structure 51 includes a pointed cone-shaped protruding structure 511 and an arc-shaped protruding structure 511, which are distributed alternately.

[0083] It should be noted that if Figure 8 As shown, when the slope structure 51 has a protruding structure 511 , the area of ​​the second reflective layer 5 corresponding to the bottom surface of the epitaxial structure 2 can be raised as a whole to form a protruding structure 511 of relatively large size.

[0084] In this embodiment, the height difference between the top and the root of the protrusion structure 511 may range from 0.2 to 1 um, for example, 0.2 um, 0.3 um, 0.4 um, 0.5 um, 0.6 um, 0.7 um, 0.8 um, 0.9 um, and 1 um.

[0085] like Fig.16 As shown, this embodiment further provides a light-emitting device, including a circuit substrate 200 and at least one light-emitting diode 100 fixed to the surface of the circuit substrate 200 , and the light-emitting diode 100 is the light-emitting diode mentioned above.

[0086] Embodiment 2

[0087] like Figure 5 As shown, this embodiment provides a light emitting diode. Different from the first embodiment, a roughened structure 24 is disposed on the sidewall of the epitaxial structure 2 of this embodiment.

[0088] In this embodiment, the epitaxial structure 2 may be configured to have an inclined sidewall. The angle β of the sidewall of the epitaxial structure 2 relative to the back of the epitaxial structure 2 may be in the range of 30° to 70°, for example, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, etc. The epitaxial structure 2 is provided with an inclined sidewall, which increases the chance of light escaping from the epitaxial structure 2, reduces the propagation path of light in the epitaxial structure 2 to a certain extent, reduces the absorption of light by the material, and improves the output efficiency of light.

[0089] In this embodiment, a roughened structure 24 is disposed on the sidewall of the epitaxial structure 2 , and the height difference of the roughened structure 24 can be set to a range of 0.1 to 0.5 um.

[0090] The roughening structure 24 may be a regular patterned structure or an irregular patterned structure. In addition, the roughening structure 24 may be passivated after being manufactured. For example, the roughening structure 24 may be a pyramid-shaped pointed cone structure distributed in an array on the side wall of the epitaxial structure 2.

[0091] In this embodiment, the roughened structure 24 itself can be used to improve the internal light extraction efficiency of the vertical structure chip. At the same time, in conjunction with the inclined sidewalls of the epitaxial structure 2 and the reflective and guiding effect of the slope structure 51, the internal light extraction efficiency of the mini LED can be further improved, thereby increasing the luminous brightness.

[0092] In this embodiment, a surface of the second semiconductor layer 23 of the epitaxial structure 2 that is not covered by the first electrode 3 and the first reflective layer 4 may also be provided with a roughened structure 24 to improve the light extraction efficiency of the front portion.

[0093] Embodiment 3

[0094] like Figure 6 As shown, this embodiment provides a light emitting diode. Different from the first embodiment or the second embodiment, the light emitting diode of this embodiment further includes a lens 6.

[0095] Specifically, the lens 6 covers the front surface and at least a portion of the side wall of the epitaxial structure 2 , and is used to guide a portion of the light emitted from the epitaxial structure 2 toward the axial direction.

[0096] The "partial light" here mainly refers to the large-angle light emitted from the side of the epitaxial structure 2, which seriously deviates from the axial direction. The large-angle light is guided to the axial direction as much as possible with the help of the lens 6. It should be noted that the "guided axial direction" here does not necessarily mean completely coinciding with the axial direction, but means reducing the angle between the light emission direction and the axial direction, which may coincide or exist at a certain angle.

[0097] Embodiment 4

[0098] like Fig.15 As shown, this embodiment provides a light emitting diode. Different from the first embodiment, the second embodiment or the third embodiment, the first reflective layer 4 of the light emitting diode of this embodiment is provided with an inclined structure 41 .

[0099] Specifically, the inclined structure 41 of the first reflective layer 4 may adopt a structure that is the same as or similar to the sloped structure 51 on the second reflective layer 5 .

[0100] In this embodiment, if Fig.15 As shown, at least the back side of the first reflective layer 4 corresponding to the first electrode 3 is provided with an inclined structure 41. When the light in the epitaxial structure 2 is vertically or obliquely directed to the bottom of the first electrode 3, it will be directed to the inclined structure 41 of the first reflective layer 4, and the inclined structure 41 will reflect the light. Since the inclined structure 41 has an inclined surface, the light vertically directed to the bottom surface of the first electrode 3 will be directed to the surface of the second reflective layer 5 in an inclined manner by the inclined surface of the inclined structure 41, and the second reflective layer 5 will further guide the light to the side wall direction of the epitaxial structure 2.

[0101] In this embodiment, it is preferred that the inclined structure 41 is arranged to be symmetrical with respect to the axial center line where the center position of the first electrode 3 is located.

[0102] The above description is only a partial embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A light emitting diode, characterized in that: include: A substrate (1) having a substrate front side and a substrate back side arranged opposite to each other, wherein the extending direction perpendicular to the substrate front side is called an axial direction; An epitaxial structure (2) is formed on the front side of the substrate, the epitaxial structure (2) comprising a first semiconductor layer (21), an active layer (22), and a second semiconductor layer (23) stacked in sequence from the front side of the substrate; A first electrode (3), located above the second semiconductor layer (23) and conductively connected to the second semiconductor layer (23); A first reflective layer (4) is arranged between the first electrode (3) and the second semiconductor layer (23); A second reflective layer (5) is arranged between the first semiconductor layer (21) and the substrate (1), wherein at least a surface of the second reflective layer (5) corresponding to the lower portion of the first electrode (3) is arranged as a sloped structure (51) having an inclined wall surface.

2. The light emitting diode according to claim 1, characterized in that: The epitaxial structure (2) has an inclined side wall.

3. The light emitting diode according to claim 2, characterized in that: The angle between the side wall of the epitaxial structure (2) and the back surface of the epitaxial structure (2) is in the range of 30° to 70°.

4. The light emitting diode according to claim 2, characterized in that: The side wall of the epitaxial structure (2) is provided with a roughening structure (24).

5. The light emitting diode according to claim 4, characterized in that: The height difference of the roughened structure (24) ranges from 0.1 to 0.5 um.

6. The light emitting diode according to claim 1, characterized in that: It also includes a lens (6) that covers the front surface and at least part of the side wall of the epitaxial structure (2) and is used to guide part of the light emitted from the epitaxial structure (2) in an axial direction.

7. The light emitting diode according to claim 1, characterized in that: It comprises a transparent encapsulation layer (7) which at least covers the surface of the epitaxial structure (2).

8. The light emitting diode according to claim 1, characterized in that: It comprises a second electrode (8) formed on the back side of the substrate (1) and conductively connected to the first semiconductor layer (21).

9. The light emitting diode according to claim 1, characterized in that: The first reflective layer (4) completely covers the surface of the second semiconductor layer (23).

10. The light emitting diode according to claim 1, characterized in that: At least an inclined structure (41) is provided on the back side of the first reflective layer (4) corresponding to the bottom of the first electrode (3).

11. The light emitting diode according to claim 10, characterized in that: The inclined structure (41) is symmetrical about the axial center line where the center position of the first electrode (3) is located.

12. The light emitting diode according to claim 1, characterized in that: The projection boundary of the first electrode (3) onto the front surface of the substrate does not exceed the projection boundary of the slope structure (51) onto the front surface of the substrate.

13. The light emitting diode according to claim 1, characterized in that: The center position of the slope-shaped structure (51) as a whole coincides with the center position of the first electrode (3) in the axial direction, and the slope-shaped structure (51) as a whole is a symmetrical structure with respect to its own center position.

14. The light emitting diode according to claim 13, characterized in that: The center position of the first electrode (3) coincides with the center position of the epitaxial structure (2) in the axial direction.

15. The light emitting diode according to any one of claims 1 to 14, characterized in that The sloped structure (51) comprises at least one protruding structure (511), and the protruding structure (511) is provided with an inclined side wall.

16. The light emitting diode according to claim 15, characterized in that: The protruding structure (511) has inclined side walls that are symmetrically arranged about its own center position.

17. The light emitting diode according to claim 15, characterized in that: The surface morphology of the inclined side wall is a plane, an arc surface or a combination of the two.

18. The light emitting diode according to claim 15, characterized in that: The sloped structure (51) comprises a plurality of protruding structures (511), and the plurality of protruding structures (511) are distributed in an array along the back side of the epitaxial structure (2).

19. The light emitting diode according to claim 15, characterized in that: The height difference between the top and the root of the protrusion structure (511) ranges from 0.2 to 1 um.

20. A light emitting device, characterized in that: The invention comprises a circuit substrate and at least one light emitting diode fixed to a surface of the circuit substrate, wherein the light emitting diode comprises the light emitting diode according to any one of claims 1 to 19.

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