Light emitting diode and light emitting device

Abstract

The application provides a light emitting diode and a light emitting device, wherein the light emitting diode comprises a substrate, an epitaxial structure, a first electrode, a first reflective layer and a second reflective layer. The substrate has a substrate front surface and a substrate back surface arranged oppositely, and the direction perpendicular to the extension direction of the substrate front surface is referred to as the axial direction. The epitaxial structure is formed on the substrate front surface side, and the epitaxial structure comprises a first semiconductor layer, an active layer and a second semiconductor layer which are sequentially stacked from the substrate front surface. The first electrode is located above the second semiconductor layer and is in conductive connection with 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 position below the first electrode is provided with a slope structure having an inclined wall surface. The technical scheme of the application optimizes the light extraction efficiency and reduces the light loss caused by the electrode shielding.

Description

TECHNICAL FIELD

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

[0002] With the gradual expansion of the AR / VR (augmented reality / virtual reality) market, the application demand of Micro LED (micro light emitting diode) in AR / VR is also growing. And in the process of pursuing better small and portable application end, the size demand of Micro LED is also gradually reduced.

[0003] In the application of Micro LED products in AR / VR, the size of the chip is required to be high, and the size of the chip is often 5um, 2um, or even below 2um. In order to meet the demand of chip miniaturization as much as possible, the packaging structure of Micro LED product is generally vertical structure. In the vertical chip structure, the main light emitting direction is generally called axial direction (i.e. the direction from the back surface of the epitaxial structure to the front surface), and the electrode structure is arranged on the axial light emitting surface. The electrode structure on the light emitting surface will block part of the light emitting surface, which will affect the light emitting brightness of the product to some extent. Especially when the size of the chip is below 2um, the size of the light emitting surface will also be reduced. At this time, the electrode structure on the light emitting surface will completely block the entire light emitting surface, which will seriously affect the light emitting brightness of the product. SUMMARY

[0004] The purpose of the present application is to provide a light emitting diode and a light emitting apparatus, which optimizes the light extraction efficiency and reduces the light loss caused by electrode shielding.

[0005] In a first aspect, the present application provides a light emitting diode, which comprises a substrate, an epitaxial structure, a first electrode, a first reflective layer, and a second reflective layer. The substrate has a substrate front surface and a substrate back surface arranged oppositely, and the direction perpendicular to the extension direction of the substrate front surface is called axial direction. The epitaxial structure is formed on one side of the substrate front surface, and the epitaxial structure comprises a first semiconductor layer, an active layer, and a second semiconductor layer which are sequentially stacked from the substrate front surface. The first electrode is located above the second semiconductor layer and is in conductive connection with the second semiconductor layer. The first reflective layer is arranged between the first electrode and the second semiconductor layer, and the second reflective layer is arranged between the first semiconductor layer and the substrate. The surface of the second reflective layer corresponding to at least the first electrode is provided with a slope structure having an inclined wall surface.

[0006] In a second aspect, the present application provides a light emitting apparatus, which comprises a circuit substrate and at least one light emitting diode fixed to the surface of the circuit substrate. The light emitting diode is the light emitting diode as described above.

[0007] Compared with the prior art, the present application has at least the following beneficial effects:

[0008] The light emitting diode of the present application optimizes the light extraction efficiency and reduces the light loss caused by the electrode shielding. Specifically, when the light emitting diode generates light in the working state, part of the light is emitted towards 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 slope structure, which not only receives the light reflected by the first reflective layer, but also further reflects the light through the design of the inclined wall surface, guiding it to the side wall direction of the epitaxial structure. This design allows part or all of the light that would otherwise be blocked by the first electrode to be directed out through the side wall of the epitaxial structure, thereby significantly reducing the shielding effect of the first electrode on the front light emission of the light emitting diode, ensuring the luminous brightness and efficiency of the light emitting diode. BRIEF DESCRIPTION OF DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

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

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

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

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

[0014] Figure 5 A cross-sectional view of a light emitting diode with roughening structure according to an embodiment of the present application;

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

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

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

[0018] Figure 9A cross-sectional view of a light emitting diode with a small arc-shaped slope structure according to an embodiment of the present application;

[0019] Figure 10 A cross-sectional view of a light emitting diode with a trapezoidal slope structure according to an embodiment of the present application;

[0020] Figure 11 A cross-sectional view of a light emitting diode with a sharp taper-shaped slope structure according to an embodiment of the present application;

[0021] Figure 12 A cross-sectional view of a slope structure with a plurality of sharp taper-shaped protruding structures according to an embodiment of the present application;

[0022] Figure 13 A cross-sectional view of a slope structure with a plurality of arc-shaped protruding structures according to an embodiment of the present application;

[0023] Figure 14 A cross-sectional view of a slope structure with a plurality of mixed-shaped protruding structures according to an embodiment of the present application;

[0024] Figure 15 A cross-sectional view of a light emitting diode with a first reflective layer having an inclined structure according to an embodiment of the present application;

[0025] Figure 16 A structure view of a light emitting device according to an embodiment of the present application.

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

[0027] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a 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 accompanying drawings 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 claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0029] In order to meet the demand of chip miniaturization as much as possible, the chip size of Micro LED products is often 5um, 2um, or even less than 2um. In the chip miniaturization Micro LED product, the electrode structure of the light emitting surface will block 50% or more of the light emitting surface, especially for chips below 2um, the electrode structure almost blocks the entire light emitting surface, which seriously affects the luminous brightness of the product. In order to solve this problem, the following technical solutions are provided.

[0030] The application provides a light emitting diode, which comprises a substrate, an epitaxial structure, a first electrode, a first reflective layer and a second reflective layer. The substrate has a substrate front surface and a substrate back surface arranged oppositely, and the extension direction perpendicular to the substrate front surface is referred to as the axial direction. The epitaxial structure is formed on the substrate front surface side, and the epitaxial structure comprises a first semiconductor layer, an active layer and a second semiconductor layer which are sequentially stacked from the substrate front surface. The first electrode is located above the second semiconductor layer and is in conductive connection with 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 the surface of the corresponding second reflective layer below the first electrode is provided with a slope structure having an inclined wall surface.

[0031] The light emitting diode of the application optimizes the light extraction efficiency and reduces 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 towards 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 slope structure, which not only receives the light reflected by the first reflective layer, but also further reflects the light through the design of the inclined wall surface, guiding the light to the side wall direction of the epitaxial structure. This design allows part or all of the light that would otherwise be blocked by the first electrode to be guided out through the side wall of the epitaxial structure, thereby significantly reducing the shielding effect of the first electrode on the light emitting diode front light, ensuring the luminous brightness and efficiency of the light emitting diode.

[0032] In an optional scheme, the first semiconductor layer of the epitaxial structure is an N-type semiconductor layer, and the second semiconductor layer is a P-type semiconductor layer. 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 alternative, the first reflective layer and the second reflective layer can be DBR reflective structure or 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 structure.

[0034] ODR reflective structure is based on the waveguide effect of light and the principle of total reflection, and realizes the transmission and reflection of light through 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 completely reflective. When light enters from the partially coated reflective surface, according to the size of the incident angle, the light beam can be reflected multiple times through the partially coated reflective surface. In these reflection processes, the transmission direction of the light changes, but the total energy remains inside the mirror. When the incident angle reaches a certain condition, it exceeds the critical angle, and the light cannot be transmitted from the partially coated surface, but the total reflection phenomenon occurs. At this time, the light will be reflected back and forth between the partially coated reflective surface and the completely reflective surface, maintaining transmission inside the mirror. ODR can reflect the light beam from one position to another, realizing the transmission and reflection of light.

[0035] DBR reflective structure is a reflector formed by the periodic stacking of thin films with different refractive indices. When light passes through these thin films with different refractive indices, the light reflected by each layer changes in phase angle and then combines together to obtain strong reflected light. The DBR reflectivity is determined by the refractive index difference of each layer of material and the number of DBR periods.

[0036] In general, ODR and DBR each have unique advantages and application scenarios. ODR is suitable for occasions that require extensive coverage and beam control due to its omnidirectional reflection capability, while DBR is suitable for applications that require specific wavelength reflection and laser stability due to its high reflectivity and wavelength selectivity. According to different design requirements and application needs, the skilled person in the art can choose the appropriate reflective structure.

[0037] In an alternative, the first electrode can be partially or fully overlapped with the first reflective layer, or the first electrode can be partially or fully overlapped with the second reflective layer.

[0038] For example, for a light emitting diode with a chip size of 2um or more, the size of the first electrode can be smaller than the size of the second semiconductor layer, i.e. the first electrode does not completely cover the second semiconductor layer. In this case, the first reflective layer can completely cover the front surface of the second semiconductor layer, or cover part of the front surface of the second semiconductor layer, but the front surface area of the first reflective layer at least contains the shielding area of the first electrode. For example, for a light emitting diode with a chip size of less than 2um, the size of the first electrode can be substantially equal to the size of the second semiconductor layer, i.e. the first electrode substantially completely covers the second semiconductor layer. In this case, the first reflective layer is arranged to completely cover the front surface of the second semiconductor layer to completely contain the shielding area of the first electrode.

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

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

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

[0042] In an optional embodiment, the side wall of the epitaxial structure is provided with a roughening structure, and the height difference of the roughening structure can be in the range of 0.1um to 0.5um. The roughening structure can be a regular patterned structure or an irregular patterned structure. In addition, the roughening structure can be passivated after being made. The roughening structure improves the extraction efficiency of light in the vertical structure chip.

[0043] The light emitting diode of the present application comprises a transparent encapsulation layer covering at least the surface of the epitaxial structure. The transparent encapsulation layer can be a multi-layer structure, for example, it can comprise a transparent film layer and a protective film layer stacked in sequence. The transparent encapsulation layer can play a role of increasing the transparency and protection. The transparent encapsulation layer (especially the transparent film layer) mainly increases the intensity of the emitted light by reducing the reflection of light at the chip-air interface, 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 air for a long time or being mechanically damaged, and improve the stability and reliability of the chip.

[0044] In an optional solution, the projection boundary of the first electrode to the front surface of the substrate can exceed the projection boundary of the slope structure to the front surface of the substrate. That is, after the light rays vertically incident to the bottom surface of the first electrode are reflected back by the first reflective layer, only part of the reflected light rays are received by the slope structure and reflected to the sidewall of the epitaxial structure, so as to reduce the loss of light rays and improve the luminous brightness and luminous efficiency.

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

[0046] In an optional solution, the slope structure can be an asymmetric structure. The inclined walls of the slope structure located below the first electrode can be inclined to the same side, so as to reflect most of the light rays to the single-side sidewall of the epitaxial structure and improve the luminous brightness of the single-side sidewall.

[0047] In an optional solution, the center position of the slope structure as a whole coincides with the center position of the first electrode in the axial direction, and the slope structure as a whole is a symmetric structure about its own center position, while the center position of the first electrode coincides with the center position of the epitaxial structure in the axial direction. Thus, the amount of light reflected by the slope structure to the sidewalls of the epitaxial structure on both sides can be substantially the same, so as to make the luminous brightness of the sidewalls of the epitaxial structure on both sides substantially the same.

[0048] In an optional solution, the slope structure comprises at least one protruding structure, and the protruding structure is provided with an inclined sidewall for reflecting light rays.

[0049] In an optional solution, the surface form 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 sharp cone, a trapezoid, a circular arc, etc.

[0050] In an optional solution, the protruding structure can be an asymmetric structure.

[0051] In an optional solution, the protruding structure can be a symmetric structure, that is, each protruding structure has an inclined sidewall symmetrically arranged about its own center position.

[0052] In an optional solution, the slope structure comprises a plurality of protruding structures, and the plurality of protruding structures are arrayed along the back surface of the epitaxial structure. The inclined walls of the plurality of protruding structures can receive as much as possible the light rays reflected by the first reflective layer at multiple angles, so as to reduce the loss of brightness.

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

[0054] In an optional embodiment, the light-emitting diode also includes a lens covering the front side and at least part of the sidewalls of the epitaxial structure, used to guide a portion of the light emitted from the epitaxial structure along the axial direction. Here, "partial light" mainly refers to large-angle light emitted from the side of the epitaxial structure, which deviates significantly from the axial direction. The lens guides the large-angle emitted light as much as possible along the axial direction. It should be noted that "guiding along the axial direction" here does not necessarily mean complete alignment with the axial direction, but rather reducing the angle between the light emission direction and the axial direction; they may coincide or there may be a certain angle.

[0055] In an optional embodiment, at least the back surface of the first reflective layer corresponding to the lower part of the first electrode is provided with an inclined structure. When light from the epitaxial structure is directed perpendicularly or obliquely toward the lower part 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, light that is directed perpendicularly toward the bottom surface of the first electrode will be directed obliquely toward the surface of the second reflective layer by the inclined surface of the inclined structure, and further guided by the second reflective layer toward the sidewall direction of the epitaxial structure.

[0056] In an optional configuration, the tilted structure of the first reflective layer can be the same as or similar to the sloping structure of the second reflective layer. Furthermore, the tilted structure can be configured to be symmetrical about the axial centerline of the first electrode's center position.

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

[0058] To provide a more detailed description of the light-emitting diode of this application, the following embodiments are provided. It should be noted that the technical features and solutions in the following embodiments can be used in combination with each other without conflict.

[0059] Example 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 surface and a substrate back surface arranged oppositely, and the direction perpendicular to the extension direction of the substrate front surface is referred to as the axial direction. The epitaxial structure 2 is formed on the substrate front surface side, and the epitaxial structure 2 includes a first semiconductor layer 21, an active layer 22, and a second semiconductor layer 23 arranged in sequence from the substrate front surface. The first electrode 3 is arranged above the second semiconductor layer 23 and is in electrical connection with 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 position below the first electrode 3 is arranged in a slope structure 51 having an inclined wall surface.

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

[0063] The light-emitting diode of the embodiment includes a transparent encapsulation layer 7 covering at least the surface of the epitaxial structure 2. The transparent encapsulation layer 7 can be a multi-layer structure, for example, can include a transparent film layer and a protective film layer arranged in sequence. The transparent encapsulation layer 7 can play a role of increasing the light transmittance and protection. The transparent encapsulation layer 7 (especially the transparent film layer) can mainly increase the intensity of the emitted light by reducing the reflection of the light at the chip-air interface, 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 air for a long time or being mechanically damaged, and improve the stability and reliability of the chip.

[0064] It should be noted that, referring to Figure 4 The light-emitting diode of the embodiment can include a substrate 1 and a plurality of independent epitaxial structures 2 formed on the same substrate 1.

[0065] The light-emitting diode of the embodiment optimizes the light extraction efficiency and reduces the light loss caused by the electrode shielding. Specifically, when the light-emitting diode generates light in the working state, part of the light is emitted towards the bottom surface 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 to have a slope structure 51, which not only receives the light reflected by the first reflective layer 4, but also further reflects the light through the design of the inclined wall surface, guiding the light to the side wall direction of the epitaxial structure 2. This design makes part or all of the light that would otherwise be blocked by the first electrode 3 be guided out through the side wall of the epitaxial structure 2, thereby significantly reducing the shielding effect of the first electrode 3 on the front light emission of the light-emitting diode, and ensuring the luminous intensity and efficiency of the light-emitting diode.

[0066] In the 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 can all be GaN-based materials. The epitaxial structure 2 can be prepared by chemical vapor deposition.

[0067] In the embodiment, the first reflective layer 4 and the second reflective layer 5 can be DBR reflective structures or OBR reflective structures. 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 to be selected according to actual needs and the characteristics of the reflective structure.

[0068] In the embodiment, as shown in Figures 1 to 3 , the projection boundary of the first electrode 3 to the front surface of the first reflective layer 4 can completely coincide with the boundary of the front surface area of the first reflective layer 4, or the projection boundary of the first electrode 3 to the front surface of the first reflective layer 4 can be located within the boundary of the front surface area of the first reflective layer 4.

[0069] For example, for a light-emitting diode with a chip size of 2 um or more, referring to Figure 1 and Figure 2 , the size of the first electrode 3 can 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, at this time, the first reflective layer 4 can completely cover the front surface of the second semiconductor layer 23, or cover part of the front surface of the second semiconductor layer 23, but the front surface area of the first reflective layer 4 at least contains the shielding area of the first electrode 3. For example, for a light-emitting diode with a chip size of less than 2 um, referring to Figure 3 , the size of the first electrode 3 can 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 set to completely cover the front surface of the second semiconductor layer 23 to completely contain the shielding area of the first electrode 3.

[0070] In the embodiment, the first reflective layer 4 can be set to completely cover the surface of the second semiconductor layer 23 to make the light all be guided out from the side surface of the epitaxial structure 2.

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

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

[0073] In the embodiment, as shown in Figure 7 , the slope structure 51 can be an asymmetric structure. The inclined wall surface of the slope structure 51 located below the first electrode 3 can be inclined to the same side to reflect most of the light rays to the single-side sidewall of the epitaxial structure 2 and improve the luminous brightness of the single-side sidewall.

[0074] In the embodiment, as shown in Figures 8 to 14 , it is preferred that the center position of the whole slope structure 51 coincides with the center position of the first electrode 3 in the axial direction, and the whole slope structure 51 is symmetric about its own center position, while 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 light amount reflected by the slope structure to the sidewalls of the epitaxial structure on both sides be substantially the same to make the luminous brightness of the sidewalls of the epitaxial structure on both sides be substantially the same.

[0075] In the embodiment, as shown in Figures 7 to 14 , the slope structure 51 comprises at least one protruding structure 511 provided with an inclined sidewall for reflecting light rays. For example, Figures 7 to 11 the slope structure 51 has only one protruding structure 511 as shown in Figures 12 to 14 the slope structure 51 has a plurality of protruding structures 511.

[0076] In the embodiment, as shown in Figures 7 to 11 , the surface form of the inclined sidewall of the protruding structure 511 can be a plane, an arc surface or a combination of the two. The cross-sectional shape of the protruding structure can be a triangle Figure 7 , a sharp cone Figure 11 , a trapezoid Figure 10 , a circular arc Figure 8 andFigure 9 )wait.

[0077] In this embodiment, the protrusion structure 511 can be an asymmetrical structure. For example... Figure 7 As shown, the protruding structure 511 is triangular, but the inclination and side length of its two side walls are different, achieving differentiated light reflection capabilities on both sides.

[0078] In this embodiment, the protrusion structure 511 can be a symmetrical structure. For example... Figures 8 to 11 As shown, each protrusion structure 511 preferably has inclined sidewalls that are symmetrically arranged about its own center position.

[0079] In this embodiment, as Figures 8 to 14 As shown, the sloping structure 51 includes multiple protrusions 511, which are arranged in an array along the back surface of the extension structure 2. The inclined walls of the multiple protrusions 511 can receive light reflected from the first reflective layer 4 at multiple angles as much as possible, reducing brightness loss.

[0080] Meanwhile, in this embodiment, such as Figures 8 to 14 As shown, the center position of the slope structure 51 coincides with the center position of the first electrode 3 in the axial direction. The slope structure 51 is symmetrical about its own center position. In addition, with the multiple arrays of protruding structures 511 included therein, it can further improve the light reflection efficiency and improve the light emission brightness and brightness uniformity of the two side walls of the epitaxial structure 2.

[0081] In this embodiment, the slope structure 51 may include multiple identical protrusions 511. For example... Figure 12 As shown, the slope structure 51 includes multiple pointed, conical protrusions 511. (As...) Figure 13 As shown, the slope structure 51 includes multiple arc-shaped protrusions 511.

[0082] In this embodiment, the slope structure 51 may include multiple protrusions 511 with different structures. For example... Figure 14 As shown, the slope structure 51 includes a conical protrusion structure 511 and an arc-shaped protrusion structure 511, which are distributed alternately.

[0083] It should be noted that, as 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 extension structure 2 can be raised as a whole to form a relatively large protruding structure 511.

[0084] In the embodiment, the height difference between the top and the root of the protruding structure 511 can 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, or 1 um.

[0085] As shown in FIG. 1, the embodiment provides a light-emitting device, which comprises a circuit substrate 200 and at least one light-emitting diode 100 fixed to the surface of the circuit substrate 200. The light-emitting diode 100 is the aforementioned light-emitting diode. Figure 16

[0086] Embodiment Two

[0087] As shown in FIG. 2, the embodiment provides a light-emitting diode, which is different from the embodiment one in that the sidewall of the epitaxial structure 2 of the embodiment is provided with a roughening structure 24. Figure 5

[0088] In the embodiment, the epitaxial structure 2 can be provided with an inclined sidewall. The included angle β of the sidewall of the epitaxial structure 2 relative to the back surface of the epitaxial structure 2 can range from 30° to 70°, for example, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, or 70°. 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 light output efficiency.

[0089] In the embodiment, the roughening structure 24 is arranged on the sidewall of the epitaxial structure 2, and the height difference of the roughening structure 24 can range from 0.1 to 0.5 um.

[0090] The roughening structure 24 can be a regular patterned structure or an irregular patterned structure. In addition, the roughening structure 24 can be passivated after being made. For example, the roughening structure 24 can be a pyramid-shaped sharp structure arranged in an array on the sidewall of the epitaxial structure 2.

[0091] In the embodiment, the roughening structure 24 itself can be used to improve the internal light extraction efficiency of the vertical structure chip. At the same time, in combination with the reflection and guidance of the inclined sidewall of the epitaxial structure 2 and the slope structure 51, the internal light extraction efficiency of the mini light-emitting diode can be further improved, and the luminous brightness can be improved.

[0092] In the embodiment, the surface of the second semiconductor layer 23 of the epitaxial structure 2 which is not covered by the first electrode 3 and the first reflective layer 4 can also be provided with the roughening structure 24 to improve the light extraction efficiency of the front surface part.

[0093] Embodiment Three

[0094] As​​Figure 6 As shown, this embodiment provides a light-emitting diode. Unlike embodiment one or embodiment two, the light-emitting diode in this embodiment also includes a lens 6.

[0095] Specifically, the lens 6 covers the front side and at least part of the sidewalls of the epitaxial structure 2, and is used to guide part of the light rays emitted from the epitaxial structure 2 axially.

[0096] The "partial light rays" here mainly refer to the large-angle light rays emitted from the side of the extension structure 2, which deviate significantly from the axial direction. The lens 6 is used to guide the large-angle light rays as much as possible along the axial direction. It should be noted that "guiding along the axial direction" here does not necessarily mean that it is completely aligned with the axial direction, but rather that it means reducing the angle between the light emission direction and the axial direction. They may be aligned, or there may be a certain angle.

[0097] Example 4

[0098] like Figure 15 As shown, this embodiment provides a light-emitting diode. Unlike Embodiment 1, Embodiment 2 or Embodiment 3, the first reflective layer 4 of the light-emitting diode in this embodiment is provided with an inclined structure 41.

[0099] Specifically, the inclined structure 41 of the first reflective layer 4 can adopt the same or similar structure as the slope structure 51 on the second reflective layer 5.

[0100] In this embodiment, as Figure 15 As shown, at least the back surface of the first reflective layer 4 corresponding to the lower part of the first electrode 3 is provided with an inclined structure 41. When light from the epitaxial structure 2 is directed vertically or obliquely towards the lower part of the first electrode 3, it will be directed towards 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, light that is directed vertically towards the bottom surface of the first electrode 3 will be directed obliquely towards the surface of the second reflective layer 5 by the inclined surface of the inclined structure 41, and further guided by the second reflective layer 5 towards the sidewall direction of the epitaxial structure 2.

[0101] In this embodiment, it is preferable that the inclined structure 41 is symmetrical about the axial centerline where the center of the first electrode 3 is located.

[0102] The above description is only a partial embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A light emitting diode, characterized by, The application relates to a semiconductor light emitting device. The application comprises: a substrate (1) having a substrate front surface and a substrate back surface arranged oppositely, and the direction perpendicular to the extension direction of the substrate front surface is called the axial direction; an epitaxial structure (2) formed on the substrate front surface side, the epitaxial structure (2) comprising a first semiconductor layer (21), an active layer (22), and a second semiconductor layer (23) arranged in sequence on the substrate front surface; a first electrode (3) arranged above the second semiconductor layer (23) and electrically connected with the second semiconductor layer (23); a first reflective layer (4) arranged between the first electrode (3) and the second semiconductor layer (23); 2. The light emitting diode of claim 1, wherein, a second reflective layer (5) arranged between the first semiconductor layer (21) and the substrate (1), and the surface of the second reflective layer (5) corresponding to at least the first electrode (3) is arranged as a slope structure (51) having an inclined wall surface.

3. The light emitting diode of claim 2, wherein, The epitaxial structure (2) has an inclined side wall.

4. The light emitting diode of claim 2, wherein, The included angle between the side wall of the epitaxial structure (2) and the back surface of the epitaxial structure (2) ranges from 30 DEG to 70 DEG.

5. The light emitting diode of claim 4, wherein, The side wall of the epitaxial structure (2) is provided with a roughening structure (24).

6. The light emitting diode of claim 1, wherein, The height difference of the roughening structure (24) ranges from 0.1 to 0.5 um.

7. The light emitting diode of claim 1, wherein, The application further comprises a lens (6) covering the front surface and at least part of the side wall of the epitaxial structure (2) and used for guiding part of the light emitted from the epitaxial structure (2) to the axial direction.

8. The light emitting diode of claim 1, wherein, The application comprises a transparent encapsulation layer (7) covering at least the surface of the epitaxial structure (2).

9. The light emitting diode of claim 1, wherein, The application comprises a second electrode (8) formed on the back surface of the substrate (1) and electrically connected with the first semiconductor layer (21).

10. The light emitting diode of claim 1, wherein, The first reflective layer (4) completely covers the surface of the second semiconductor layer (23).

11. The light emitting diode of claim 10, wherein, The back surface of the first reflective layer (4) corresponding to at least the first electrode (3) is provided with an inclined structure (41).

12. The light emitting diode of claim 1, wherein the first and second semiconductor layers are formed of a group III-V compound semiconductor. The inclined structure (41) is symmetrically arranged about the axial center line of the center position of the first electrode (3).

13. The light emitting diode of claim 1, wherein, The projection boundary of the first electrode (3) to the substrate front surface does not exceed the projection boundary of the slope structure (51) to the substrate front surface.

14. The light emitting diode of claim 13, wherein, The center position of the whole slope structure (51) coincides with the center position of the first electrode (3) in the axial direction, and the whole slope structure (51) is symmetrically arranged about its own center position.

15. The light emitting diode of any one of claims 1 to 14, wherein, The center position of the first electrode (3) coincides with the center position of the epitaxial structure (2) in the axial direction.

16. The light emitting diode of claim 15, wherein, The slope structure (51) comprises at least one protruding structure (511) provided with an inclined side wall.

17. The light emitting diode of claim 15, wherein, The protruding structure (511) has an inclined side wall symmetrically arranged about its own center position.

18. The light emitting diode of claim 15, wherein, The surface form of the inclined side wall is a plane, an arc surface or a combination of the two.

19. The light emitting diode of claim 15, wherein, The slope structure (51) comprises a plurality of the protruding structures (511) which are arranged in an array along the back surface of the epitaxial structure (2). The height difference between the top end and the root of the protruding structure (511) ranges from 0.2 to 1 um.

20. A light emitting device comprising: A lighting device comprising a circuit board and at least one light emitting diode fixed to a surface of the circuit board, the light emitting diode comprising the light emitting diode of any one of claims 1 to 19.

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