Light emitting device, method of manufacturing the same, and light emitting panel

Abstract

Embodiments of the present disclosure provide a light-emitting device and a preparation method thereof, and a light-emitting panel, and relate to the technical field of semiconductors, and are used to improve the reflectivity of light, thereby improving the brightness and brightness uniformity of the light-emitting device. The light-emitting device comprises a light-emitting functional layer, a first Bragg reflection layer, a first ohmic contact layer, a second Bragg reflection layer and a metal reflection layer. The first Bragg reflection layer and the first ohmic contact layer are sequentially stacked on the first surface, and are both located in the second Bragg reflection layer. A plurality of first Bragg reflectors of the first Bragg reflection layer are separately arranged. The first ohmic contact layer comprises a plurality of first ohmic contact structures. One first ohmic contact structure is arranged on the side of one first Bragg reflector away from the first surface. The second Bragg reflection layer comprises a plurality of contact holes, and one contact hole exposes one first ohmic contact structure. The metal reflection layer is electrically connected with the first ohmic contact layer through the contact hole.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and in particular to a light-emitting device and its fabrication method, and a light-emitting panel. Background Technology

[0002] Light-emitting diodes (LEDs) have been widely used due to their advantages such as self-illumination, low driving voltage, high luminous efficiency, and fast response speed.

[0003] However, LED chips still suffer from low brightness due to low reflectivity and uneven brightness. Summary of the Invention

[0004] The purpose of this disclosure is to provide a light-emitting device and its preparation method, as well as a light-emitting panel, for improving the reflectivity of light, thereby improving the brightness and brightness uniformity of the light-emitting device.

[0005] To achieve the above objectives, the embodiments of this disclosure provide the following technical solutions: On one hand, a light-emitting device is provided, comprising a light-emitting functional layer, a first Bragg reflector layer, a first ohmic contact layer, a second Bragg reflector layer, and a metal reflector layer. The light-emitting functional layer includes a first surface and a second surface disposed opposite to each other. The first Bragg reflector layer is disposed on the first surface. The first Bragg reflector layer includes a plurality of first Bragg mirrors, which are separately disposed. The first ohmic contact layer is disposed on the side of the first Bragg reflector layer away from the first surface. The first ohmic contact layer includes a plurality of first ohmic contact structures. One first ohmic contact structure is disposed on the side of a first Bragg mirror away from the first surface. The second Bragg reflector layer is disposed on the first surface, and both the first Bragg reflector layer and the first ohmic contact layer are located within the second Bragg reflector layer. The second Bragg reflector layer includes a plurality of contact holes, one contact hole exposing one first ohmic contact structure. The metal reflector layer is disposed on the side of the second Bragg reflector layer away from the first surface. The metal reflector layer is electrically connected to the first ohmic contact layer through the contact holes.

[0006] The aforementioned light-emitting device includes a light-emitting functional layer, a first Bragg reflector layer, a first ohmic contact layer, a second Bragg reflector layer, and a metal reflector layer. Both the first and second Bragg reflector layers are disposed on the first surface of the light-emitting functional layer, and the first Bragg reflector layer and the first ohmic contact layer are stacked within the second Bragg reflector layer. The metal reflector layer is located on the side of the second Bragg reflector layer away from the first surface. The metal reflector layer is electrically connected to the first ohmic contact structure through a contact hole, thereby injecting current into the light-emitting functional layer, causing the light-emitting functional layer to emit light.

[0007] Understandably, in the first ohmic contact layer, since current can be injected into the light-emitting functional layer through the first ohmic contact structure, the area where the first ohmic contact structure is located can serve as the current injection region of the light-emitting device, while other areas can serve as the non-current injection region of the light-emitting device. When the light emitted from the light-emitting functional layer exits from the current injection region, a first Bragg reflector is disposed between the first ohmic contact structure and the light-emitting functional layer. The light is preferentially reflected by the first Bragg reflector and then exits from the second surface. When the light emitted from the light-emitting functional layer exits from the non-current injection region, the light is preferentially reflected by the second Bragg reflector layer and then exits from the second surface.

[0008] In other words, light emitted from the light-emitting functional layer toward the first surface can preferentially pass through the first Bragg reflector and the second Bragg reflector layer and be reflected to the second surface. Especially in the current injection region, most of the light does not need to pass through the first ohmic contact structure and then be reflected by the metal reflector layer, thereby reducing the possibility of light being absorbed and scattered by the first ohmic contact structure, improving the reflectivity and light extraction efficiency of light in the current injection region, thereby improving the overall effective reflectivity and uniformity of light, and thus improving the brightness and brightness uniformity of the light-emitting device.

[0009] In some embodiments, the material of the second Bragg reflective layer is different from the material of the first Bragg reflective layer. The reflectivity of the material of the first Bragg reflective layer is greater than that of the material of the metallic reflective layer.

[0010] In some embodiments, the light-emitting functional layer includes an N-type semiconductor layer, a light-emitting active layer, and a P-type semiconductor layer stacked together. A first surface is the surface of the N-type semiconductor layer away from the light-emitting active layer, and a second surface is the surface of the P-type semiconductor layer away from the light-emitting active layer. The first Bragg reflector layer includes a first semiconductor material layer and a second semiconductor material layer stacked together, with the first semiconductor material layer located on the side of the second semiconductor material layer closest to the first surface. The elements contained in the material of the first semiconductor material layer include those contained in the material of the P-type semiconductor layer. The elements contained in the material of the second semiconductor material layer include those contained in the material of the first ohmic contact layer.

[0011] In some embodiments, the materials of the P-type semiconductor layer, the first ohmic contact layer, the first semiconductor material layer, and the second semiconductor material layer all include III-V compound semiconductor materials.

[0012] In some embodiments, the thickness of the first Bragg reflective layer in a direction perpendicular to the first surface ranges from 100 nm to 500 nm.

[0013] In some embodiments, the orthographic projection of the first ohmic contact layer on the first surface is within the range of the orthographic projection of the first Bragg reflective layer on the first surface.

[0014] In some embodiments, the light-emitting device further includes a transparent conductive layer disposed on the side of the first ohmic contact layer away from the first surface and electrically connected to the first ohmic contact layer. The transparent conductive layer is located within the second Bragg reflective layer, and a contact hole exposes the transparent conductive layer. The metal reflective layer is electrically connected to the first ohmic contact layer through the contact hole and the transparent conductive layer.

[0015] In some embodiments, the light-emitting device further includes a second ohmic contact layer and a plurality of first pads. The second ohmic contact layer is disposed on a second surface, and the plurality of first pads are disposed on the side of the second ohmic contact layer away from the first surface and are electrically connected to the second ohmic contact layer. The light-emitting device further includes a bonding layer, a substrate, and a second pad sequentially stacked on the side of the metal reflective layer away from the first surface. The metal reflective layer is electrically connected to the bonding layer.

[0016] On the other hand, a method for fabricating a light-emitting device is also provided, which includes the following steps S1 to S5: Step S1: Form a light-emitting functional layer, the light-emitting functional layer including a first surface and a second surface disposed opposite to each other; Step S2: A first Bragg reflective layer and a first ohmic contact layer are sequentially formed on the first surface using an epitaxial growth process; Step S3: A plurality of first Bragg reflectors are formed in the first Bragg reflector layer, and the plurality of first Bragg reflectors are disposed separately; a plurality of first ohmic contact structures are formed in the first ohmic contact layer, and a first ohmic contact structure is disposed on the side of a first Bragg reflector away from the first surface; Step S4: A second Bragg reflective layer is formed on the first surface, and both the first Bragg reflective layer and the first ohmic contact layer are located within the second Bragg reflective layer; the second Bragg reflective layer includes multiple contact holes, and one contact hole exposes a first ohmic contact structure; Step S5: A metal reflective layer is formed on the side of the second Bragg reflective layer away from the first surface; the metal reflective layer is electrically connected to the first ohmic contact layer through a contact hole.

[0017] In the above-described method for fabricating a light-emitting device, a first Bragg reflector layer and a first ohmic contact layer are sequentially formed on the first surface of the light-emitting functional layer using an epitaxial growth process. The light-emitting functional layer can emit light. Multiple first Bragg reflectors are formed in the first Bragg reflector layer, and multiple first ohmic contact structures are formed in the first ohmic contact layer. A second Bragg reflector layer is formed on the first surface, and both the first Bragg reflector layer and the first ohmic contact layer are located within the second Bragg reflector layer. The second Bragg reflector layer includes multiple contact holes, with each contact hole exposing one first ohmic contact structure. A metal reflector layer is formed on the side of the second Bragg reflector layer away from the first surface. The metal reflector layer is electrically connected to the first ohmic contact layer through the contact holes, thereby injecting current into the light-emitting functional layer, causing the light-emitting functional layer to emit light.

[0018] Understandably, in the first ohmic contact layer, since current can be injected into the light-emitting functional layer through the first ohmic contact structure, the area where the first ohmic contact structure is located can serve as the current injection region of the light-emitting device, while other areas can serve as the non-current injection region of the light-emitting device. When the light emitted from the light-emitting functional layer exits from the current injection region, a first Bragg reflector is disposed between the first ohmic contact structure and the light-emitting functional layer. The light is preferentially reflected by the first Bragg reflector and then exits from the second surface. When the light emitted from the light-emitting functional layer exits from the non-current injection region, the light is preferentially reflected by the second Bragg reflector layer and then exits from the second surface.

[0019] In other words, light emitted from the light-emitting functional layer toward the first surface can preferentially pass through the first Bragg reflector and the second Bragg reflector layer and be reflected to the second surface. Especially in the current injection region, most of the light does not need to pass through the first ohmic contact structure and then be reflected by the metal reflector layer, thereby reducing the possibility of light being absorbed and scattered by the first ohmic contact structure, improving the reflectivity and light extraction efficiency of light in the current injection region, thereby improving the overall effective reflectivity and uniformity of light, and thus improving the brightness and brightness uniformity of the light-emitting device.

[0020] On the other hand, a light-emitting panel is also provided, which includes a plurality of light-emitting devices and a circuit board as described in the above embodiments. The light-emitting devices are disposed on the circuit board and electrically connected to the circuit board.

[0021] The light-emitting panel described above has the same structure and beneficial technical effects as the light-emitting devices provided in some of the above embodiments, and will not be described again here. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this disclosure, the accompanying drawings used in some embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this disclosure.

[0023] Figure 1 This is a structural diagram of a light-emitting device according to some embodiments; Figure 2 for Figure 1 A magnified view of the light-emitting device at point M; Figure 3 A flowchart illustrating a method for fabricating a light-emitting device according to some embodiments; Figures 4-8 The diagram shows the steps of a method for fabricating a light-emitting device according to some embodiments; Figure 9 This is a structural diagram of a light-emitting panel according to some embodiments. Detailed Implementation

[0024] The technical solutions in some embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments provided in this disclosure are within the scope of protection of this disclosure.

[0025] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as open-ended and encompassing, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples.

[0026] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0027] In describing some embodiments, the terms "coupled" and "connected," and their derivative expressions, may be used. The term "connected" should be interpreted broadly; for example, a "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection via an intermediate medium. The term "coupled," for example, indicates that two or more components have direct physical or electrical contact. The term "coupled" or "communicatively coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content of this document.

[0028] "At least one of A, B and C" has the same meaning as "at least one of A, B or C", both including the following combinations of A, B and C: only A, only B, only C, combinations of A and B, combinations of A and C, combinations of B and C, and combinations of A, B and C.

[0029] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0030] As used herein, depending on the context, the term “if” may optionally be interpreted as meaning “when”, “in the event of”, “in response to determination”, or “in response to detection”. Similarly, depending on the context, the phrase “if it is determined that…” or “if [the stated condition or event] is detected” may optionally be interpreted as meaning “in the event of determination that…”, “in response to determination that…”, “when [the stated condition or event] is detected”, or “in response to the detection of [the stated condition or event]”.

[0031] The use of “applies to” or “configured to” in this article implies an open and inclusive language that does not preclude applicability to or configuration to devices that perform additional tasks or steps.

[0032] In addition, the use of “based on” implies openness and inclusivity, because processes, steps, calculations or other actions “based on” one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0033] As used herein, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from the given value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the given quantity (i.e., the limitations of the measurement system).

[0034] As used herein, “parallel,” “perpendicular,” and “equal” include the described situation and situations that are similar to the described situation, within an acceptable deviation range, which is determined by those skilled in the art taking into account the measurement under discussion and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, “parallel” includes absolute parallelism and approximate parallelism, where an acceptable deviation range for approximate parallelism may be, for example, within 5°; “perpendicular” includes absolute perpendicularity and approximate perpendicularity, where an acceptable deviation range for approximate perpendicularity may also be, for example, within 5°; “equal” includes absolute equality and approximate equality, where an acceptable deviation range for approximate equality may be, for example, a difference between the two equals being less than or equal to 5% of either one.

[0035] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can mean that the layer or element is directly on the other layer or substrate, or that there is an intermediate layer between the layer or element and the other layer or substrate.

[0036] This document describes exemplary embodiments with reference to cross-sectional views and / or plan views, which are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are enlarged for clarity. Therefore, variations in shape relative to the drawings are contemplated due to, for example, manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as being limited to the shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing processes. For example, etched areas shown as rectangular would typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shapes of the areas of the device, nor are they intended to limit the scope of the exemplary embodiments.

[0037] In related technologies, light-emitting diode (LED) chips typically use distributed Bragg reflectors (DBRs) made of all dielectric materials to improve light reflectivity. For example, DBRs can utilize a stack of silicon oxide (SiO2) and titanium oxide (TiO2) to achieve high light reflectivity.

[0038] However, to achieve low-resistance ohmic contacts, LED chips need to be annealed at high temperatures. During this process, metal atoms (such as Au and Zn) interact with the P-type GaP (gallium phosphide) in the LED chip. Taking the AuZn and GaP contact as an example, Zn atoms diffuse to replace Ga vacancies, forming a heavily doped region near the interface, which is crucial for forming a tunnel junction ohmic contact. These diffusion traces, defects, and alloy phases become effective light absorption centers. When photons reach this region, they may not only be absorbed by the metal bulk but also be heavily absorbed and scattered in the rough, complex interface layer, resulting in an effective reflectivity far lower than the theoretical reflectivity of the metal material.

[0039] Furthermore, in order to reduce the resistance of LED chips, the size of the current injection (CB) aperture is usually large, which further expands the light loss area and leads to a decrease in light extraction efficiency.

[0040] To address at least one of the aforementioned problems, in one aspect, embodiments of this disclosure provide a light-emitting device. Figure 1 This is a structural diagram of a light-emitting device according to some embodiments.

[0041] See Figure 1 The light-emitting device 10 includes a light-emitting functional layer 1, a first Bragg reflective layer 2, a first ohmic contact layer 3, a second Bragg reflective layer 4, and a metal reflective layer 5.

[0042] For example, the light-emitting device 10 can be an LED chip.

[0043] The light-emitting functional layer 1 includes a first surface 101 and a second surface 102 disposed opposite to each other. It is understood that the light-emitting functional layer 1 is used to emit light.

[0044] For example, the light emitted by the light-emitting functional layer 1 can be emitted in the direction of the first surface 101 and the second surface 102, and the second surface 102 can be the light-emitting surface of the light-emitting device 10. For example, the wavelength of the light emitted by the light-emitting functional layer 1 can be in the red light band, that is, light with a wavelength range of 600nm to 700nm.

[0045] See also Figure 1 A first Bragg reflector layer 2 is disposed on the first surface 101. The first Bragg reflector layer 2 includes a plurality of first Bragg reflectors 21, and the plurality of first Bragg reflectors 21 are disposed separately.

[0046] For example, the size and shape of the plurality of first Bragg reflectors 21 may be the same or different, and the distance between two adjacent first Bragg reflectors 21 may be equal or unequal. The embodiments of this disclosure are illustrated by taking the example that the plurality of first Bragg reflectors 21 are all the same in size and shape, and the distance between two adjacent first Bragg reflectors 21 is equal.

[0047] For example, under the action of light emitted by the light-emitting functional layer 1, the material of the first Bragg reflective layer 2 has a reflectivity of 99% or greater than that of the light.

[0048] See also Figure 1 The first ohmic contact layer 3 is disposed on the side of the first Bragg reflector 2 away from the first surface 101. The first ohmic contact layer 3 includes a plurality of first ohmic contact structures 31. One first ohmic contact structure 31 is disposed on the side of the first Bragg reflector 21 away from the first surface 101.

[0049] For example, the light-emitting functional layer 1 can be electrically connected to the first ohmic contact layer 3 through the first Bragg reflector layer 2. The area where the first ohmic contact layer 3 is projected onto the first surface 101 can be used as the "current injection region" of the light-emitting device 10, and other areas of the first surface 101 can be used as the "non-current injection region" of the light-emitting device 10.

[0050] See also Figure 1 The second Bragg reflector layer 4 is disposed on the first surface 101, and both the first Bragg reflector layer 2 and the first ohmic contact layer 3 are located within the second Bragg reflector layer 4. The second Bragg reflector layer 4 includes a plurality of contact holes 40, each contact hole 40 exposing a first ohmic contact structure 31.

[0051] For example, the contact hole 40 can be a CB hole. The second Bragg reflective layer 4 can be a stack of silicon oxide (SiO2) and titanium oxide (TiO2), for example, the second Bragg reflective layer 4 can be a six-layer dielectric material stack of SiO2 / TiO2 / SiO2 / TiO2 / SiO2 / TiO2.

[0052] For example, along the Z direction, the thickness of the SiO2 layer can range from 100nm to 300nm, the thickness of the TiO2 layer can range from 60nm to 100nm, and the total thickness of the second Bragg reflective layer 4 can range from 600nm to 1000nm.

[0053] For example, the contact hole 40 may expose a portion of the surface of the first ohmic contact structure 31, or it may expose the entire surface of the first ohmic contact structure 31. The embodiments of this disclosure are illustrated using the example of the contact hole 40 exposing a portion of the surface of the first ohmic contact structure 31.

[0054] For example, the pattern of the second Bragg reflective layer 4 can be a photolithographic matrix array pattern with a diameter ranging from 4μm to 6μm and a spacing ranging from 20μm to 40μm.

[0055] See also Figure 1 The metal reflective layer 5 is disposed on the side of the second Bragg reflective layer 4 away from the first surface 101. The metal reflective layer 5 is electrically connected to the first ohmic contact layer 3 through the contact hole 40.

[0056] For example, the material of the metal reflective layer 5 can be a stack of Ag / TiW / Ti / Pt / Au. For instance, along the Z direction, the thickness of the Ag (silver) layer can range from 200 nm to 600 nm, the thickness of the TiW (titanium-tungsten) layer can range from 50 nm to 400 nm, the thickness of both the Ti (titanium) layer and the Pt (platinum) layer can range from 100 nm to 300 nm, and the thickness of the Au (gold) layer can range from 500 nm to 900 nm.

[0057] For example, in the current injection region of the aforementioned light-emitting device 10, the first ohmic contact layer 3 is electrically connected to the metal reflective layer 5. During the formation of the light-emitting device 10 through a high-temperature annealing process, metal atoms in the metal reflective layer 5 diffuse into the first ohmic contact layer 3, forming a tunnel junction ohmic contact in a heavily doped region. These diffusion traces, defects, and alloy phases become effective light absorption centers. When photons emitted by the light-emitting functional layer 1 reach this region, they may not only be absorbed by the bulk of the metal reflective layer 5, but also be largely absorbed and scattered in the rough, complex interface layer, resulting in an effective reflectivity that is far lower than the theoretical reflectivity of the metal reflective layer 5 material, thereby reducing the brightness of the light-emitting device 10.

[0058] Furthermore, since there is no second Bragg reflector 4 at the location of the contact hole 40, in the absence of the first Bragg reflector 2, the light entering from the current injection area can only pass through the first ohmic contact layer 3, be reflected by the metal reflector 5, and then exit from the second surface 102. Since the reflectivity of the metal reflector 5 is lower than that of the DBR, the above arrangement will result in a lower reflectivity of the light at the current injection area.

[0059] The aforementioned light-emitting device 10 includes a light-emitting functional layer 1, a first Bragg reflector layer 2, a first ohmic contact layer 3, a second Bragg reflector layer 4, and a metal reflector layer 5. The first Bragg reflector layer 2 and the second Bragg reflector layer 4 are both disposed on the first surface 101 of the light-emitting functional layer 1, and the first Bragg reflector layer 2 and the first ohmic contact layer 3 are stacked within the second Bragg reflector layer 4. The metal reflector layer 5 is located on the side of the second Bragg reflector layer 4 away from the first surface 101. The metal reflector layer 5 is electrically connected to the first ohmic contact structure 31 through a contact hole 40, thereby injecting current into the light-emitting functional layer 1, causing the light-emitting functional layer 1 to emit light.

[0060] It is understandable that in the first ohmic contact layer 3, since current can be injected into the light-emitting functional layer 1 through the first ohmic contact structure 31, the area where the first ohmic contact structure 31 is located can serve as the current injection region of the light-emitting device 10, and other areas can serve as the non-current injection region of the light-emitting device 10. When the light emitted from the light-emitting functional layer 1 exits from the current injection region, a first Bragg reflector 21 is disposed between the first ohmic contact structure 31 and the light-emitting functional layer 1, and the light is preferentially reflected by the first Bragg reflector 21 and then exits from the second surface 102. When the light emitted from the light-emitting functional layer 1 exits from the non-current injection region, the light is preferentially reflected by the second Bragg reflector layer 4 and then exits from the second surface 102.

[0061] In other words, the light emitted from the light-emitting functional layer 1 toward the first surface 101 can preferentially pass through the first Bragg reflector 21 and the second Bragg reflector layer 4 and be reflected to the second surface 102. Especially in the current injection region, most of the light does not need to pass through the first ohmic contact structure 31 and then be reflected by the metal reflector layer 5, thereby reducing the possibility of light being absorbed and scattered by the first ohmic contact structure 31, improving the reflectivity and light emission efficiency of the light in the current injection region, thereby improving the overall effective reflectivity and uniformity of the light, and thus improving the brightness and brightness uniformity of the light-emitting device 10.

[0062] In some embodiments, see Figure 1 The material of the second Bragg reflector 4 is different from that of the first Bragg reflector 2.

[0063] For example, the material of the first Bragg reflector layer 2 can be a semiconductor material. The material of the second Bragg reflector layer 4 can be an insulating dielectric material, thereby realizing the electrical connection between the first ohmic contact structure 31 and the light-emitting functional layer 1, so that current can be transmitted from the first ohmic contact structure 31 through the second Bragg reflector layer 4 to the light-emitting functional layer 1, thereby realizing the light emission of the light-emitting functional layer 1.

[0064] Understandably, in the current injection region, a first Bragg reflector layer 2 made of semiconductor material with high reflectivity that can be integrated below the current channel is set, while in the non-current injection region, a second Bragg reflector layer 4 made of insulating dielectric material with the highest reflectivity and lowest light absorption is set to cover it, thereby optimizing the overall reflectivity of the light-emitting device 10. Through the aforementioned setting of the first Bragg reflector layer 2 and the second Bragg reflector layer 4, the light-emitting device 10 can achieve an additional improvement in light extraction efficiency, directly translating into higher external quantum efficiency (EQE) and optical power (mW).

[0065] For example, the parameters of the first Bragg reflector 2 (e.g., the number of layers of the first Bragg reflector 2, its material doping type, or thickness) and the parameters of the second Bragg reflector 4 (e.g., the number of layers of the second Bragg reflector 4, its material, or thickness) can be optimized independently to finely adjust the optocoupler of the current injection region and the pure optical performance of the main light-emitting region, respectively, to obtain performance curves that cannot be achieved by a traditional single structure.

[0066] See also Figure 1 The reflectivity of the material of the first Bragg reflector layer 2 is greater than that of the material of the metal reflector layer 5.

[0067] For example, when the light emitted by the light-emitting functional layer 1 is red light, the material of the metal reflective layer 5 has a reflectivity of about 90% for red light, while the material of the first Bragg reflective layer 2 has a reflectivity of more than 95% for red light.

[0068] Understandably, when the light emitted from the light-emitting functional layer 1 exits from the current injection region, a first Bragg reflector 21 is disposed between the first ohmic contact structure 31 and the light-emitting functional layer 1. The light is preferentially reflected by the first Bragg reflector 21, and most of the light does not need to pass through the first ohmic contact structure 31 but is reflected by the metal reflective layer 5, thus transforming the current injection region from an "optically dark region" to an "optically bright region." By setting the reflectivity of the material of the first Bragg reflector 2 to be greater than that of the material of the metal reflective layer 5, the reflectivity of the light in the current injection region and the brightness of this region can be further improved, thereby further improving the overall reflectivity of the light, as well as the brightness and brightness uniformity of the light-emitting device 10.

[0069] In some embodiments, see Figure 1 The light-emitting functional layer 1 includes an N-type semiconductor layer 11, a light-emitting active layer 12, and a P-type semiconductor layer 13 stacked together. The first surface 101 is the surface of the N-type semiconductor layer 11 away from the light-emitting active layer 12, and the second surface 102 is the surface of the P-type semiconductor layer 13 away from the light-emitting active layer 12.

[0070] For example, the material of the light-emitting active layer 12 can be a multiple quantum well (MQW) light-emitting layer. For instance, the light-emitting active layer 12 can emit red light when current is injected. The material of the N-type semiconductor layer 11 can be GaAs (gallium arsenide).

[0071] For example, the P-type semiconductor layer 13 may include a stacked confinement layer 131 and a transition layer 132. The confinement layer 131 is in contact with the light-emitting active layer 12, and the transition layer 132 is in contact with the first Bragg reflector layer 2.

[0072] Figure 2 for Figure 1 A magnified view of the light-emitting device at point M.

[0073] See Figure 1 and Figure 2 The first Bragg reflector layer 2 includes a first semiconductor material layer 211 and a second semiconductor material layer 212 stacked together, with the first semiconductor material layer 211 located on the side of the second semiconductor material layer 212 near the first surface 101.

[0074] It is understood that the first semiconductor material layer 211 is in contact with the P-type semiconductor layer 13, for example, the first semiconductor material layer 211 is in contact with the transition layer 132. The second semiconductor material layer 212 is in contact with the first ohmic contact layer 3.

[0075] The elements contained in the material of the first semiconductor material layer 211 include the elements contained in the material of the P-type semiconductor layer 13. The elements contained in the material of the second semiconductor material layer 212 include the elements contained in the material of the first ohmic contact layer 3.

[0076] It is understood that the first semiconductor material layer 211 is in contact with the P-type semiconductor layer 13, and the material of the first semiconductor material layer 211 is lattice-matched with the material of the P-type semiconductor layer 13. The second semiconductor material layer 212 is in contact with the first ohmic contact layer 3, and the material of the second semiconductor material layer 212 is lattice-matched with the material of the first ohmic contact layer 3.

[0077] For example, during the formation of the light-emitting device 10, after forming the P-type semiconductor layer 13, a first semiconductor material layer 211 with a lattice adapted to the P-type semiconductor layer 13 can be formed by an epitaxial growth process. Furthermore, the first semiconductor material layer 211 and the second semiconductor material layer 212 are also lattically adapted. The second semiconductor material layer 212 can then be formed on the first semiconductor material layer 211 by an epitaxial growth process. Subsequently, a first ohmic contact layer 3 with a lattice adapted to the second semiconductor material layer 212 can be formed on the second semiconductor material layer 212 by an epitaxial growth process.

[0078] In some embodiments, see Figure 1 and Figure 2 The materials of the P-type semiconductor layer 13, the first ohmic contact layer 3, the first semiconductor material layer 211, and the second semiconductor material layer 212 all include III-V compound semiconductor materials.

[0079] For example, the material of the N-type semiconductor layer 11 can be AlGaInP (aluminum gallium indium phosphide). The material of the confinement layer 131 can be AlGaInP, and the material of the transition layer 132 can be AlInP (aluminum indium phosphide). The material of the first semiconductor material layer 211 can be AlInP, and the material of the second semiconductor material layer 212 can be AlGaInP. The material of the first ohmic contact layer 3 can be GaP (gallium phosphide), and the material of the first ohmic contact layer 3 is also doped with carbon atoms, with a carbon atom doping concentration greater than 5 × 10⁻⁶. 19 cm -3 .

[0080] For example, along the Z direction, the thickness of the first ohmic contact layer 3 can range from 50 nm to 250 nm.

[0081] For example, at least two refractive indices in the first Bragg reflector layer 2 need to have a certain difference. Among the materials of the first semiconductor material layer 211 and the second semiconductor material layer 212, one is a high refractive index material and the other is a low refractive index material. For example, the refractive index of AlInP material is about 3.25 and the refractive index of AlGaInP material is about 3.1, thereby achieving high reflectivity of the first Bragg reflector layer 2.

[0082] In some embodiments, see Figure 1 Along the direction Z perpendicular to the first surface 101, the thickness of the first Bragg reflective layer 2 ranges from 100nm to 500nm. For example, the thickness of the first Bragg reflective layer 2 can be 100nm, 200nm, 300nm, 400nm, or 500nm.

[0083] It is understandable that the thickness of the first Bragg reflective layer 2 is set in the range of 100nm to 500nm. Within this range, the greater the thickness, the higher the reflectivity. By setting the thickness as described above, the first Bragg reflective layer 2 can be located within the second Bragg reflective layer 4, thereby ensuring the adhesion between the subsequent metal reflective layer 5 and the second Bragg reflective layer 4, and thus improving the structural reliability of the light-emitting device 10.

[0084] In some embodiments, see Figure 1 The orthographic projection of the first ohmic contact layer 3 onto the first surface 101 is located within the range of the orthographic projection of the first Bragg reflective layer 2 onto the first surface 101.

[0085] In some embodiments, see Figure 1 The light-emitting device 10 also includes a transparent conductive layer 6.

[0086] For example, the material of the transparent conductive layer 6 can be indium tin oxide (ITO), which has a light transmittance of about 96%.

[0087] For example, the thickness of the transparent conductive layer 6 along the Z direction can range from 40 nm to 200 nm.

[0088] A transparent conductive layer 6 is disposed on the side of the first ohmic contact layer 3 away from the first surface 101 and is electrically connected to the first ohmic contact layer 3. The transparent conductive layer 6 is located within the second Bragg reflective layer 4, and the contact hole 40 exposes the transparent conductive layer 6. The metal reflective layer 5 is electrically connected to the first ohmic contact layer 3 through the contact hole 40 and the transparent conductive layer 6.

[0089] It is understandable that when the light emitted from the light-emitting functional layer 1 exits from the current injection region, a small portion of the light will pass through the first Bragg reflector 21, and then sequentially through the first ohmic contact structure 31 and the transparent conductive layer 6, illuminating the metal reflective layer 5. After being reflected by the metal reflective layer 5, it will exit from the second surface 12. The high light transmittance of the transparent conductive layer 6 helps to reduce the loss of this small portion of light, thereby further increasing the amount of light emitted from the second surface 12, and thus further improving the brightness and brightness uniformity of the light-emitting device 10.

[0090] In some embodiments, see Figure 1 The light-emitting device 10 also includes a second ohmic contact layer 7 and a plurality of first pads 71. The second ohmic contact layer 7 is disposed on the second surface 102, and the plurality of first pads 71 ​​are disposed on the side of the second ohmic contact layer 7 away from the first surface 101 and are electrically connected to the second ohmic contact layer 7.

[0091] For example, the material of the second ohmic contact layer 7 can be GaAs (gallium arsenide). The material of the first pad 71 can be gold, a gold-germanium-nickel alloy (AuGeNi), or a gold stack. For example, the thickness of the first pad 71 along the Z direction can range from 2 μm to 3 μm.

[0092] See also Figure 1 The light-emitting device 10 further includes a bonding layer 81, a substrate 8, and a second pad 82, which are sequentially stacked on the side of the metal reflective layer 5 away from the first surface 101. The metal reflective layer 5 is electrically connected to the bonding layer 81.

[0093] For example, the bonding layer 81 can be a stack of four metal materials: Ti, Pt, Au, and In. For instance, along the Z direction, the thickness of the Ti metal layer, Pt metal layer, and Au metal layer can all range from 100 nm to 300 nm, and the thickness of the In metal layer can range from 500 nm to 900 nm.

[0094] For example, the substrate 8 can be made of Si (silicon). The second pad 82 can be made of a two-layer metal stack of Ti and Au.

[0095] For example, along the Z-direction, the thickness of both the Ti metal layer and the Au metal layer can range from 50 nm to 200 nm. The thickness of the light-emitting device 10 can range from 180 μm to 200 μm.

[0096] Understandably, the light-emitting device 10 can be electrically connected to the circuit board via the first pad 71 and the second pad 82. Current can be injected into the P-type semiconductor layer 13 through the first pad 71 and flow out from the N-type semiconductor layer 11 through the second pad 82, thereby enabling the light-emitting active layer 12 to emit light and thus enabling the light-emitting device 10 to light up.

[0097] For example, see [link to previous article] Figure 1 The light-emitting device 10 also includes a passivation layer 9, which at least covers the sidewall of the light-emitting functional layer 1 and exposes the second surface 102, thereby ensuring the light-emitting area of ​​the light-emitting device 10 while reducing the corrosion of the light-emitting device 10 by water vapor and oxygen.

[0098] For example, the material of the passivation layer 9 can be silicon nitride (SiNx), and the thickness of the passivation layer 9 can range from 300 nm to 600 nm.

[0099] On the other hand, embodiments of this disclosure also provide a method for fabricating a light-emitting device. Figure 3 A flowchart illustrating a method for fabricating a light-emitting device according to some embodiments; Figures 4-8 The diagram shows the steps of a method for fabricating a light-emitting device according to some embodiments.

[0100] See Figure 3 The preparation method includes the following steps S1 to S5: Step S1: See Figure 4 A light-emitting functional layer 1 is formed, which includes a first surface 101 and a second surface 102 disposed opposite to each other.

[0101] For example, the light-emitting functional layer 1 includes an N-type semiconductor layer 11, a light-emitting active layer 12, and a P-type semiconductor layer 13 stacked together. A first surface 101 is the surface of the N-type semiconductor layer 11 away from the light-emitting active layer 12, and a second surface 102 is the surface of the P-type semiconductor layer 13 away from the light-emitting active layer 12. The P-type semiconductor layer 13 includes a confinement layer 131 and a transition layer 132 stacked together.

[0102] For example, a metal-organic vapor deposition (MOCVD) process can be used to sequentially form an N-type semiconductor layer 11, a light-emitting active layer 12, a confinement layer 131, and a transition layer 132 on a substrate 90.

[0103] For example, see Figure 1 Before forming the N-type semiconductor layer 11, a second ohmic contact layer 7 can also be formed by MOCVD process.

[0104] The second ohmic contact layer 7 can be made of GaAs (gallium arsenide), and the N-type semiconductor layer 11 can be made of AlGaInP (aluminum gallium indium phosphide). The confinement layer 131 can be made of AlGaInP, and the transition layer 132 can be made of AlInP (aluminum indium phosphide). After the above growth process is completed, the first surface 101 and the second surface 102 can be cleaned.

[0105] For example, the substrate 90 can be a GaAs substrate. Before forming the N-type semiconductor layer 11, a GaAs buffer layer and a GaInP etch stop layer can be sequentially grown on the substrate 90 by MOCVD process.

[0106] Step S2: See Figure 5 Through an epitaxial growth process, a first Bragg reflective layer 2 and a first ohmic contact layer 3 are sequentially formed on the first surface 101.

[0107] For example, an MOCVD process can be used to sequentially grow a first Bragg reflective layer 2 and a first ohmic contact layer 3 on the first surface 101. The first Bragg reflective layer 2 includes a first semiconductor material layer 211 and a second semiconductor material layer 212 stacked together, with the first semiconductor material layer 211 located on the side of the second semiconductor material layer 212 closer to the first surface 101.

[0108] Understandably, after forming the P-type semiconductor layer 13, a first semiconductor material layer 211 with a lattice compatible with the P-type semiconductor layer 13 can be formed through epitaxial growth. Furthermore, the first semiconductor material layer 211 and the second semiconductor material layer 212 are also lattically compatible. The second semiconductor material layer 212 can then be formed on the first semiconductor material layer 211 through epitaxial growth. Subsequently, a first ohmic contact layer 3 with a lattice compatible with the second semiconductor material layer 212 can be formed on the second semiconductor material layer 212 through epitaxial growth.

[0109] For example, the first semiconductor material layer 211 can be made of AlInP, and the second semiconductor material layer 212 can be made of AlGaInP. The first ohmic contact layer 3 can be made of GaP (gallium phosphide), and the first ohmic contact layer 3 is also doped with carbon atoms, with a carbon atom doping concentration greater than 5 × 10¹⁹ cm⁻³.

[0110] For example, see [link to previous article] Figure 5 After forming the first ohmic contact layer 3, an electron beam evaporation method can be used to deposit a transparent conductive layer 6, which can also serve as part of the ohmic contact layer. For example, the material of the transparent conductive layer 6 can be ITO. Then, a photolithography process is used to form a photolithographic matrix pattern with a diameter range of 10μm to 20μm and a spacing range of 20μm to 40μm. Next, using an ITO etching solution, the above structure is immersed at 65°C for 70s to 80s to etch the ITO deposited on the surface into a pattern, thereby achieving the patterning of the transparent conductive layer 6.

[0111] Step S3: See Figure 6 A plurality of first Bragg reflectors 21 are formed in the first Bragg reflector layer 2, and the plurality of first Bragg reflectors 21 are disposed separately. A plurality of first ohmic contact structures 31 are formed in the first ohmic contact layer 3, and a first ohmic contact structure 31 is disposed on the side of a first Bragg reflector 21 away from the first surface 101.

[0112] For example, an inductively coupled plasma dry etching (ICP) process can be used to etch the first ohmic contact layer 3 and the first Bragg reflective layer 2 until the target window of the second semiconductor material layer 212 is etched, and then the photoresist is removed.

[0113] Step S4: See Figure 7A second Bragg reflector layer 4 is formed on the first surface 101, and both the first Bragg reflector layer 2 and the first ohmic contact layer 3 are located within the second Bragg reflector layer 4. The second Bragg reflector layer 4 includes a plurality of contact holes 40, each contact hole 40 exposing a first ohmic contact structure 31.

[0114] For example, the second Bragg reflective layer 4 can be formed by electron beam evaporation. For instance, the second Bragg reflective layer 4 can be a stack of silicon oxide (SiO2) and titanium oxide (TiO2), such as a six-layer dielectric material stack of SiO2 / TiO2 / SiO2 / TiO2 / SiO2 / TiO2. Next, the second Bragg reflective layer 4 is etched using photolithography to form a photolithographic matrix array pattern with a diameter ranging from 4μm to 6μm and a spacing ranging from 20μm to 40μm.

[0115] Next, an ICP dry etching process was used to etch down to the transparent conductive layer 6, thereby etching out the contact points between the metal and semiconductor materials. Afterwards, the photoresist was removed. Step S5: See Figure 8 A metallic reflective layer 5 is formed on the side of the second Bragg reflective layer 4 away from the first surface 101. The metallic reflective layer 5 is electrically connected to the first ohmic contact layer 3 through a contact hole 40.

[0116] For example, the material of the metal reflective layer 5 can be a stack of Ag / TiW / Ti / Pt / Au. For instance, along the Z direction, the thickness of the Ag (silver) layer can range from 200 nm to 600 nm, the thickness of the TiW (titanium-tungsten) layer can range from 50 nm to 400 nm, the thickness of both the Ti (titanium) layer and the Pt (platinum) layer can range from 100 nm to 300 nm, and the thickness of the Au (gold) layer can range from 500 nm to 900 nm.

[0117] For example, a high-temperature annealing process can be used during the formation of the metal reflective layer 5 to reduce the resistance of the ohmic contact. For instance, the process parameters of the high-temperature annealing process can be an annealing temperature range of 360°C to 400°C and an annealing time range of 15 min to 20 min.

[0118] For example, see Figure 1 After step S5 above, the method for preparing the light-emitting device 10 further includes cleaning the Au (gold) layer of the metal reflective layer 5 by a combination of Acetone (ACE) and citric acid.

[0119] Next, a substrate 300 is provided. Bonding materials are deposited on the surface of the substrate 300 and the surface of the Au (gold) layer of the metal reflective layer 5 using electron beam evaporation to form a bonding layer 81. For example, the bonding layer 81 can be a stack of four metal materials: Ti, Pt, Au, and In. For example, along the Z-direction, the thicknesses of the Ti, Pt, and Au metal layers can all range from 100 nm to 300 nm, and the thickness of the In metal layer can range from 500 nm to 900 nm.

[0120] Next, the bonding layer 81 on the substrate 300 is bonded to the bonding layer 81 on the Au (gold) layer of the metal reflective layer 5, and the entire structure is placed in a bonding machine to form a bond. The bonding temperature range can be 200℃~220℃.

[0121] Then, the substrate 90, GaAs buffer layer and GaInP etching stop layer can be removed sequentially using a wet etching process with a wet solution.

[0122] See also Figure 1 The second ohmic contact layer 7 pattern of the GaAs material that needs to be retained can be formed by photolithography, and the GaAs that does not need to be retained on the surface can be removed by chemical solution method, and the photoresist can be removed.

[0123] Next, a pattern for the required pads is formed using photolithography, and the first pad 71 is formed by electron beam evaporation. The material of the first pad 71 can be gold, a gold-germanium-nickel alloy (AuGeNi), or a gold stack. After the first pad 71 is formed by evaporation, the photoresist is removed.

[0124] Then, the structure formed above is subjected to high-temperature annealing, with an annealing temperature range of 300℃~360℃ and an annealing time range of 10min~15min.

[0125] See also Figure 1 The second surface 102 of the N-type semiconductor layer 11 is roughened by chemical wet etching using photolithography to form a pattern that requires surface roughening. After roughening, the photoresist is removed. Then, the desired size and pattern of the light-emitting active layer 12 are formed by photolithography, and etched down to the transition layer 132 using ICP etching. The photoresist is then removed.

[0126] Next, a passivation layer 9 can be deposited on the second surface 102 using a PECVD process. The material of the passivation layer 9 can be silicon nitride (SiNx), and the thickness of the passivation layer 9 can range from 300 nm to 600 nm. Then, the passivation layer 9 is etched using a photolithography process to expose the entire light-emitting surface, protecting only the sidewall area. In other words, the passivation layer 9 at least covers the sidewalls of the light-emitting functional layer 1 and exposes the second surface 102.

[0127] For example, a wet etching process can be used to expose the SiNx layer on the second surface 102 using a buffered oxide etch (BOE) solution, and then remove the photoresist.

[0128] Finally, the above structure is thinned to 180μm~200μm, and then a second pad 82 is formed by electron beam evaporation. The second pad 82 can be a metal material layer covering the back of the substrate 300, and the second pad 82 can be a stack of two metal materials, Ti and Au. Then, by laser cutting and dicing, the above structure is separated into individual light-emitting diode devices to form such as Figure 1 The light-emitting device 10 shown.

[0129] In the fabrication method of the light-emitting device 10 described above, a first Bragg reflector layer 2 and a first ohmic contact layer 3 are sequentially formed on the first surface 101 of the light-emitting functional layer 1 through an epitaxial growth process. The light-emitting functional layer 1 can emit light. A plurality of first Bragg reflectors 21 are formed in the first Bragg reflector layer 2, and a plurality of first ohmic contact structures 31 are formed in the first ohmic contact layer 3. A second Bragg reflector layer 4 is formed on the first surface 101, and both the first Bragg reflector layer 2 and the first ohmic contact layer 3 are located within the second Bragg reflector layer 4. The second Bragg reflector layer 4 includes a plurality of contact holes 40, and each contact hole 40 exposes one first ohmic contact structure 31. A metal reflector layer 5 is formed on the side of the second Bragg reflector layer 4 away from the first surface 101. The metal reflector layer 5 is electrically connected to the first ohmic contact layer 3 through the contact holes 40, thereby injecting current into the light-emitting functional layer 1, causing the light-emitting functional layer 1 to emit light.

[0130] It is understandable that in the first ohmic contact layer 3, since current can be injected into the light-emitting functional layer 1 through the first ohmic contact structure 31, the area where the first ohmic contact structure 31 is located can serve as the current injection region of the light-emitting device 10, and other areas can serve as the non-current injection region of the light-emitting device 10. When the light emitted from the light-emitting functional layer 1 exits from the current injection region, a first Bragg reflector 21 is disposed between the first ohmic contact structure 31 and the light-emitting functional layer 1, and the light is preferentially reflected by the first Bragg reflector 21 and then exits from the second surface 102. When the light emitted from the light-emitting functional layer 1 exits from the non-current injection region, the light is preferentially reflected by the second Bragg reflector layer 4 and then exits from the second surface 102.

[0131] In other words, the light emitted from the light-emitting functional layer 1 toward the first surface 101 can preferentially pass through the first Bragg reflector 21 and the second Bragg reflector layer 4 and be reflected to the second surface 102. Especially in the current injection region, most of the light does not need to pass through the first ohmic contact structure 31 and then be reflected by the metal reflector layer 5, thereby reducing the possibility of light being absorbed and scattered by the first ohmic contact structure 31, improving the reflectivity and light emission efficiency of the light in the current injection region, thereby improving the overall effective reflectivity and uniformity of the light, and thus improving the brightness and brightness uniformity of the light-emitting device 10.

[0132] On the other hand, a light-emitting panel is also provided. Figure 9 This is a structural diagram of a light-emitting panel according to some embodiments.

[0133] See Figure 9 The light-emitting panel 100 includes a plurality of light-emitting devices 10 as described in the above embodiments and a circuit board 200. The light-emitting devices 10 are disposed on the circuit board 200 and are electrically connected to the circuit board 200.

[0134] For example, the circuit board 200 can be a printed circuit board (PCB), which can supply current to the light-emitting device 10, thereby causing the light-emitting device 10 to emit light.

[0135] For example, the second pad 82 of the light-emitting device 10 can be directly soldered to the circuit board 200 for electrical connection, and the first pad 71 of the light-emitting device 10 can be electrically connected to the circuit board 200 through soldering wires.

[0136] Understandably, because the light-emitting device 10 improves the overall effective reflectivity and uniformity of light, and enhances the brightness and brightness uniformity of the light-emitting device 10, the brightness and brightness uniformity of the light-emitting panel 100 are also improved.

[0137] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A light-emitting device, characterized in that, include: The light-emitting functional layer includes a first surface and a second surface disposed opposite to each other; A first Bragg reflector layer is disposed on the first surface; The first Bragg reflector layer includes a plurality of first Bragg reflectors, and the plurality of first Bragg reflectors are disposed separately; A first ohmic contact layer is disposed on the side of the first Bragg reflector away from the first surface; the first ohmic contact layer includes a plurality of first ohmic contact structures; one first ohmic contact structure is disposed on the side of the first Bragg reflector away from the first surface; A second Bragg reflector layer is disposed on the first surface, and both the first Bragg reflector layer and the first ohmic contact layer are located within the second Bragg reflector layer; the second Bragg reflector layer includes a plurality of contact holes, one contact hole exposing a first ohmic contact structure; A metal reflective layer is disposed on the side of the second Bragg reflective layer away from the first surface; the metal reflective layer is electrically connected to the first ohmic contact layer through the contact hole.

2. The light-emitting device according to claim 1, characterized in that, The material of the second Bragg reflector is different from the material of the first Bragg reflector. The reflectivity of the material of the first Bragg reflector is greater than that of the material of the metal reflector.

3. The light-emitting device according to claim 2, characterized in that, The light-emitting functional layer includes an N-type semiconductor layer, a light-emitting active layer, and a P-type semiconductor layer stacked together; the first surface is the side surface of the N-type semiconductor layer away from the light-emitting active layer, and the second surface is the side surface of the P-type semiconductor layer away from the light-emitting active layer; The first Bragg reflector layer includes a first semiconductor material layer and a second semiconductor material layer stacked together, with the first semiconductor material layer located on the side of the second semiconductor material layer closer to the first surface; The elements contained in the material of the first semiconductor material layer include those contained in the material of the P-type semiconductor layer; the elements contained in the material of the second semiconductor material layer include those contained in the material of the first ohmic contact layer.

4. The light-emitting device according to claim 3, characterized in that, The materials of the P-type semiconductor layer, the first ohmic contact layer, the first semiconductor material layer, and the second semiconductor material layer all include III-V compound semiconductor materials.

5. The light-emitting device according to claim 1, characterized in that, Along the direction perpendicular to the first surface, the thickness of the first Bragg reflective layer ranges from 100 nm to 500 nm.

6. The light-emitting device according to claim 1, characterized in that, The orthographic projection of the first ohmic contact layer onto the first surface is within the range of the orthographic projection of the first Bragg reflective layer onto the first surface.

7. The light-emitting device according to claim 1, characterized in that, The light-emitting device further includes a transparent conductive layer, which is disposed on the side of the first ohmic contact layer away from the first surface and is electrically connected to the first ohmic contact layer; the transparent conductive layer is located within the second Bragg reflective layer, and the contact hole exposes the transparent conductive layer; The metal reflective layer is electrically connected to the first ohmic contact layer through the contact hole and the transparent conductive layer.

8. The light-emitting device according to claim 1, characterized in that, The light-emitting device further includes a second ohmic contact layer and a plurality of first pads. The second ohmic contact layer is disposed on the second surface, and the plurality of first pads are disposed on the side of the second ohmic contact layer away from the first surface and are electrically connected to the second ohmic contact layer. The light-emitting device further includes a bonding layer, a substrate, and a second pad, which are sequentially stacked on the side of the metal reflective layer away from the first surface; the metal reflective layer is electrically connected to the bonding layer.

9. A method for fabricating a light-emitting device, characterized in that, include: A light-emitting functional layer is formed, the light-emitting functional layer including a first surface and a second surface disposed opposite to each other; A first Bragg reflective layer and a first ohmic contact layer are sequentially formed on the first surface using an epitaxial growth process. A plurality of first Bragg reflectors are formed in the first Bragg reflector layer, and the plurality of first Bragg reflectors are disposed separately; a plurality of first ohmic contact structures are formed in the first ohmic contact layer, and a first ohmic contact structure is disposed on the side of a first Bragg reflector away from the first surface; A second Bragg reflector layer is formed on the first surface, and both the first Bragg reflector layer and the first ohmic contact layer are located within the second Bragg reflector layer; the second Bragg reflector layer includes a plurality of contact holes, one contact hole exposing a first ohmic contact structure; A metallic reflective layer is formed on the side of the second Bragg reflective layer away from the first surface; the metallic reflective layer is electrically connected to the first ohmic contact layer through the contact hole.

10. A light-emitting panel, characterized in that, include: Multiple light-emitting devices as described in any one of claims 1 to 8; A circuit board, wherein the light-emitting device is disposed on the circuit board and electrically connected to the circuit board.

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