Light emitting diode and light emitting device

Abstract

The invention provides a light-emitting diode and a light-emitting device, a current expansion layer of the light-emitting diode is provided with a concave area and a platform area located around the concave area, and a transparent insulating layer covers the current expansion layer and incompletely covers the platform area in the current expansion layer. The transparent conductive layer covers the transparent insulating layer and the platform area which is not covered by the transparent insulating layer, one side of the transparent conductive layer far away from the current expansion layer forms a flat surface, and the metal reflection layer covers the flat surface of the transparent conductive layer. The surface covered by the metal reflecting mirror is a flat surface, so that good mirror reflection can be formed, the reflection of light radiated by the semiconductor epitaxial laminated layer is remarkably improved, and the light emitting efficiency of the light emitting diode is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices and apparatus, and particularly to a light-emitting diode and a light-emitting device. Background Technology

[0002] Light-emitting diodes (LEDs) have advantages such as high luminous intensity, high efficiency, small size, and long lifespan, and are considered one of the most promising light sources today. In recent years, LEDs have been widely used in daily life, such as lighting, signal display, backlighting, automotive lights, and large-screen displays. At the same time, these applications have also placed higher demands on the brightness and luminous efficiency of LEDs.

[0003] For vertically oriented LEDs, a bonded metal reflector (BMR) structure is typically formed between the epitaxial layer and the substrate to improve luminous efficiency. To reduce light absorption in the ohmic contact layer and current spreading layer, hole or step structures are usually formed in the current spreading layer. These hole or step structures create a height difference in the BMR structure formed above the current spreading layer. In the case of a metal reflector, this height difference results in a non-flat surface on the bonding surface of the metal reflector. Especially at the locations of the hole or step structures with height differences, the metal reflector is prone to defects such as breakage, cracks, voids, and poor sidewall coverage, which easily disrupts the continuity and flatness of the metal mirror surface. This leads to the formation of a rough, non-reflective region in the metal reflector, affecting the emission efficiency of the metal reflector and the light extraction efficiency of the LED. Summary of the Invention

[0004] In view of the shortcomings and defects of the existing light-emitting diodes (BMRs) in terms of reflectivity, the present invention provides a light-emitting diode and a light-emitting device to solve one or more of the above-mentioned problems.

[0005] One embodiment of this application provides a light-emitting diode, which includes at least:

[0006] A semiconductor epitaxial stack includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially, and a current spreading layer located on the side of the second semiconductor layer away from the active layer; the current spreading layer has a plateau region and a recessed region surrounding the plateau region, the recessed region being recessed toward the first semiconductor layer;

[0007] A transparent insulating layer covers the side of the current spreading layer away from the second semiconductor layer, and the transparent insulating layer does not completely cover the plateau region;

[0008] A transparent conductive layer is located on the side of the current spreading layer away from the second semiconductor layer, and covers the transparent insulating layer and the platform region not covered by the transparent insulating layer. The side of the transparent conductive layer away from the current spreading layer is formed as a flat surface.

[0009] A metallic reflective layer covers the flat surface of the transparent conductive layer;

[0010] A substrate having a front side and a back side disposed opposite to each other, wherein the metal reflective layer is located on the front side of the substrate.

[0011] Another embodiment of this application provides a light-emitting device, which includes a circuit board and a light-emitting element disposed on the circuit board, wherein the light-emitting element includes the light-emitting diode provided in this application.

[0012] As described above, the light-emitting diode and light-emitting device of this application have the following beneficial effects:

[0013] The light-emitting diode of this application has a current spreading layer with a recessed region and a plateau region surrounding the recessed region. A transparent insulating layer covers the current spreading layer but does not completely cover the plateau region. A transparent conductive layer covers the transparent insulating layer and the plateau region not covered by the transparent insulating layer, and the side of the transparent conductive layer away from the current spreading layer is formed as a flat surface. A metal reflective layer covers this flat surface of the transparent conductive layer. Since the surface covered by the metal reflective layer is a flat surface, good specular reflection can be formed, significantly improving the reflection of light radiated by the semiconductor epitaxial stack and improving the light extraction efficiency of the light-emitting diode. In addition, the pad of the first electrode is formed in the region corresponding to the recessed region. Since the current spreading layer and the transparent conductive layer in the recessed region do not form an ohmic contact, current concentration is avoided, which is beneficial to the uniform diffusion of current. The pad is mainly used for wire bonding in subsequent processes such as chip packaging. The current spreading layer (further recessed region) corresponding to the pad does not have a transparent insulating layer, which can avoid the transparent insulating layer from falling off due to stress and adhesion problems during wire bonding, which is beneficial to improving device reliability. Attached Figure Description

[0014] Figure 1 The diagram shows a schematic representation of the structure of a light-emitting diode (LED) in the prior art.

[0015] Figure 2 The diagram shown is a schematic diagram of the structure of a light-emitting diode provided in Embodiment 1 of the present invention.

[0016] Figure 3 Displayed as Figure 2 A magnified schematic diagram of the partial structure at point A of the light-emitting diode shown.

[0017] Figure 4 The light-emitting diode shown as another alternative embodiment is in Figure 2 The diagram shows a magnified view of the partial structure of the LED at point A.

[0018] Figure 5 The light-emitting diode shown as another alternative embodiment is in Figure 2 The diagram shows a magnified view of the partial structure of the LED at point A.

[0019] Figure 6 Displayed as along Figure 2 The diagram shows a top view of the structure of a light-emitting diode.

[0020] Figure 7 The diagram shown is a schematic diagram of the light-emitting device provided in Embodiment 4 of the present invention.

[0021] Component designation explanation

[0022] 10. Light-emitting diode; 11. Substrate; 12. P-type semiconductor layer; 13. Current spreading layer; 14. Transparent conductive layer; 15. Metal reflector.

[0023] 100, Light Emitting Diode; 110, Substrate; 111, Front Side; 112, Back Side; 120, Semiconductor Epitaxial Stack; 121, First Semiconductor Layer; 122, Active Layer; 123, Second Semiconductor Layer; 124, Current Spreading Layer; 1241, Recessed Region; 1242, Plateau Region; 1240, Highly Doped Layer; 125, First Electrode; 1251, Pad; 1252, Extension; 126, Second Electrode; 130, Transparent Insulating Layer; 131, Opening; 140, Transparent Conductive Layer; 141, First Sublayer; 142, Second Sublayer; 150, Metal Reflective Layer; 160, Metal Bonding Layer; 170, Insulating Protective Layer.

[0024] 200, Light-emitting device; 201, Circuit board; 202, Light-emitting unit. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] like Figure 1As shown, in the prior art, a vertically structured light-emitting diode 10 includes an epitaxial structure and a substrate 11 bonded to the epitaxial structure. A current spreading layer 13 is formed on the side of the P-type semiconductor layer 12 of the epitaxial structure facing the substrate 11. This current spreading layer 13 is typically formed of GaP material and has strong light absorption, affecting the light emission performance of the light-emitting diode. To reduce the light absorption of the current spreading layer 13, it is usually partially removed, forming a structure with a height difference. A metal reflector 14 and a metal bonding layer 15 are formed on the side of the current spreading layer 13 with the height difference. The aforementioned height difference causes the metal reflector 15 formed thereon to also have… Figure 1 The elevation difference is shown. This elevation difference makes the metal reflector 15 very prone to defects such as breakage, cracks, voids, and poor coverage on the sidewalls at the elevation difference points. This will destroy the continuity and flatness of the metal mirror surface, and thus cause the metal reflector to form a rough area of ​​non-mirror reflection, affecting the reflection efficiency of the metal reflector and the light emission efficiency of the light-emitting diode.

[0027] To address the problems of low luminous efficiency and reliability of existing light-emitting diodes (LEDs), one embodiment of this application provides an LED that includes at least:

[0028] A semiconductor epitaxial stack includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially, and a current spreading layer located on the side of the second semiconductor layer away from the active layer; the current spreading layer has a plateau region and a recessed region around the plateau region, the recessed region being recessed toward the first semiconductor layer;

[0029] A transparent insulating layer covers the side of the current spreading layer away from the second semiconductor layer, and the transparent insulating layer does not completely cover the plateau region;

[0030] A transparent conductive layer is located on the side of the current spreading layer away from the second semiconductor layer, and covers the transparent insulating layer and the platform region not covered by the transparent insulating layer. The side of the transparent conductive layer away from the current spreading layer is formed as a flat surface.

[0031] A metallic reflective layer covers the flat surface of the transparent conductive layer;

[0032] A substrate having a front side and a back side disposed opposite to each other, wherein the metal reflective layer is located on the front side of the substrate.

[0033] A transparent insulating layer covers the current spreading layer but does not completely cover the plateau region therein. A transparent conductive layer covers the transparent insulating layer and the plateau region not covered by the transparent insulating layer, and the side of the transparent conductive layer away from the current spreading layer is formed as a flat surface. A metal reflective layer covers this flat surface of the transparent conductive layer. Because the surface covered by the metal reflector is a flat surface, good specular reflection can be formed, significantly improving the reflection of light radiated from the semiconductor epitaxial stack; in addition, the transparent insulating layer and the metal reflective layer form a total internal reflection structure, increasing light reflection and improving the light extraction efficiency of the light-emitting diode.

[0034] Optionally, the thickness of the transparent insulating layer is between

[0035] Optionally, the material forming the transparent insulating layer includes any one or more of magnesium fluoride, insulating oxides, and insulating nitrides.

[0036] The choice of thickness and material for the transparent insulating layer enables it to reflect light to a certain extent, thus increasing light output. On the other hand, unreflected light passes through the transparent insulating layer and enters the metal reflective layer, forming total internal reflection, which also increases light output.

[0037] Optionally, the thickness of the transparent conductive layer is between

[0038] The thickness of the transparent conductive layer ensures good conductivity and current diffusion; on the other hand, it helps to fill the recessed areas in the current spreading layer, making it easier to form a flat surface through subsequent polishing or etching.

[0039] Optionally, the transparent conductive layer includes one or a combination of indium zinc oxide, zinc oxide, and indium gallium oxide.

[0040] Optionally, the transparent conductive layer may be a single-layer structure or a multi-layer structure.

[0041] Optionally, the transparent conductive layer includes an indium tin oxide layer and an indium zinc oxide layer, the indium tin oxide layer being formed in the platform region, and the indium zinc oxide layer covering the indium tin oxide layer and the recessed region.

[0042] The material selection and layer structure design of the transparent conductive layer can be chosen according to actual needs. For example, when the transparent conductive layer is a multilayer structure, it can include an indium tin oxide layer and an indium zinc oxide layer. The indium tin oxide layer can form a good ohmic contact with the semiconductor material, which is beneficial for forming an ohmic contact with the current spreading layer in the plateau region and enhancing the electrical performance of the device. The indium zinc oxide layer has good light transmittance and low light absorption, which is beneficial for increasing light emission and improving the optical performance of the device.

[0043] Optionally, the thickness of the indium tin oxide layer is between

[0044] The thickness of the indium tin oxide layer should be such that it forms a good ohmic contact layer with the current spreading layer while minimizing light absorption.

[0045] Optionally, the light-emitting diode further includes an electrode structure, the electrode structure comprising:

[0046] A first electrode is formed above the first semiconductor layer, including a pad and an extension connected to the pad, and is projected on the plane where the light-emitting surface is located, wherein the projection of the pad is located within the projection range of the recessed area.

[0047] The second electrode is formed on the back side of the substrate and is electrically connected to the second semiconductor layer.

[0048] The first and second electrodes enable the light-emitting diode to connect electrically with the outside world, achieving its photoelectric conversion. Furthermore, the pads of the first electrode are formed in the area corresponding to the recessed region. Since the current spreading layer and the transparent conductive layer in the recessed region do not form an ohmic contact, current concentration in this area is avoided, which is beneficial for uniform current diffusion.

[0049] Optionally, in the stacking direction of the semiconductor epitaxial stack, the transparent insulating layer is not provided in the current spreading layer region corresponding to the pad of the first electrode.

[0050] Optionally, the projection of the pads onto the plane containing the front side of the substrate does not overlap with the projection of the transparent insulating layer.

[0051] The pads are mainly used for wire bonding in subsequent processes such as chip packaging. The current spreading layer (further recessed area) corresponding to the pads does not have a transparent insulating layer, which can avoid the transparent insulating layer from falling off due to stress and adhesion problems during the wire bonding process, thus improving device reliability.

[0052] Optionally, the surface layer of the plateau region of the current spreading layer is a highly doped layer, forming an ohmic contact with the transparent conductive layer.

[0053] A highly doped layer is formed on the surface of the current spreading layer. When a recessed region is formed, the highly doped layer at the corresponding position of the recessed region is removed, leaving only the highly doped layer on the surface of the plateau region. This highly doped layer forms an ohmic contact with the transparent conductive layer, which is beneficial for current diffusion and reduces the operating voltage.

[0054] Optionally, the depth of the recessed region is less than and less than or equal to the thickness of the current spreading layer.

[0055] The depth of the recessed area is set to ensure that it does not penetrate the current spreading layer and does not affect the current diffusion. In addition, it ensures that there is no highly doped layer in the recessed area, especially in the part corresponding to the pad of the first electrode, so as not to form ohmic contact with the subsequent transparent conductive layer, to prevent current concentration and affect the light output effect.

[0056] Optionally, a metal bonding layer formed between the metal reflective layer and the substrate may be further included between the substrate and the transparent conductive layer.

[0057] The metal bonding layer has good adhesion to the metal reflective layer and the substrate, achieving a strong and stable bond and improving the reliability of the light-emitting diode.

[0058] Optionally, the angle between the sidewall of the recessed area and the bottom of the recessed area is between 110° and 130°.

[0059] The angle between the sidewall and bottom of the recessed area makes the recessed part appear as a funnel shape with an opening size larger than the bottom size, which helps to improve the uniformity of the coverage of the subsequently formed transparent insulating layer, so that it can be evenly covered on both the sidewall and bottom of the recessed area.

[0060] Optionally, the transparent insulating layer extends from the bottom and sidewalls of the recess to the peripheral area of ​​the platform region, forming a first opening in the middle area of ​​the platform region.

[0061] The transparent insulating layer forms an opening in the plateau region, which facilitates the formation of ohmic contact between the subsequent transparent conductive layer and the current spreading layer, thereby improving electrical performance. In addition, the transparent insulating layer covers the outer area of ​​the plateau region, which helps to improve the adhesion of the transparent insulating layer, prevents it from falling off or peeling off, and helps to improve the reliability of the device.

[0062] Another embodiment of the present invention provides a light-emitting device, which includes a circuit board and a light-emitting element disposed on the circuit board, the light-emitting element including the light-emitting diode provided in this application. This light-emitting device includes the light-emitting diode of this application, and therefore can achieve good light extraction efficiency and brightness.

[0063] Example 1

[0064] This embodiment provides a light-emitting diode, such as Figure 2 As shown, the light-emitting diode 100 includes at least a substrate 110 and a semiconductor epitaxial stack 120. The semiconductor epitaxial stack includes a first semiconductor layer 121, an active layer 122, and a second semiconductor layer 123 stacked sequentially from top to bottom. The substrate 110 has a front side 111 and a back side 112, and the semiconductor epitaxial stack 120 is located on the front side 111 of the substrate 110.

[0065] The semiconductor epitaxial stack 120 in this embodiment can be any semiconductor epitaxial stack 120 capable of radiating light under voltage. In this embodiment, the semiconductor epitaxial stack 120 is preferably an AlGaInP-based epitaxial structure. The first semiconductor layer 121 can be an N-type layer, and correspondingly, the second semiconductor layer 123 can be a P-type layer, or vice versa. This embodiment takes an example where the first semiconductor layer 121 is an N-type layer and the second semiconductor layer 123 is a P-type layer.

[0066] In an optional embodiment, the first semiconductor layer 121 is an N-type AlInP layer used to provide electrons. The N-type AlInP layer provides electrons by doping with n-type impurities, such as Si, Ge, Sn, Se, and Te. In this embodiment, the n-type impurity is preferably Si, with a Si doping concentration of 1 × 10⁻⁶. 18 Atoms / cm3~2×10 18 Atoms / cm 3 The second semiconductor layer 123 is a P-type AlInP layer, which provides holes by doping with P-type impurities, such as Mg, Zn, Ca, Sr, C, and Ba. In this embodiment, Mg or C is preferred as the P-type impurity. The active layer 122 is a multiple quantum well layer, such as an AlGaInP / AlInP multiple quantum well layer. The active layer 122 has 2 to 100 periods, and the thickness of the well layer is 2 to 25 nm, while the thickness of the barrier layer is 2 to 25 nm. The thicknesses of the well layer and the barrier layer can be the same or different, depending on the actual needs. The active layer 122 radiates light with a wavelength of 550 nm to 950 nm.

[0067] like Figure 2 As shown, in this embodiment, the side of the first semiconductor layer 121 away from the active layer 122 is formed as the light-emitting surface of the light-emitting diode 100. The semiconductor epitaxial stack 100 also includes a current spreading layer 124 formed on the side of the second semiconductor layer 123 away from the active layer 122. The current spreading layer 124 and the second semiconductor layer 123 are semiconductor layers with the same conductivity type. For example, the current spreading layer 124 is a P-type AlGaInP layer, a GaP layer, etc. In this embodiment, the current spreading layer 124 is preferably a P-type GaP layer. The current spreading layer 124 can reduce resistance and make the current uniformly distributed throughout the entire P-type semiconductor layer, rather than concentrated near the electrodes.

[0068] In this embodiment, as Figure 2As shown, the current spreading layer 124 has a recessed region 1241 and a platform region 1242 surrounding the recessed region 1241. The recessed region 1241 can be formed by etching away a portion of the current spreading layer 124 from the current spreading layer 1241 towards the first semiconductor layer 121, without etching to the interface between the second semiconductor layer 123 and the active layer 122; that is, the bottom of the recessed region 1241 is located within the current spreading layer 124 or the second semiconductor layer 123. Optionally, the thickness of the current spreading layer 124 is between... The depth of the depression 1241 is between The aforementioned arrangement of the recessed region 1241 can reduce light absorption of the subsequently formed current spreading layer 124, thereby improving the luminous efficiency of the chip. In an optional embodiment, the shape of the longitudinal cross-section of the recessed region 1241 can be any suitable shape, such as a rectangle, triangle, trapezoid, etc.

[0069] In an optional embodiment, refer to Figure 3 The surface layer of the current spreading layer 124 away from the second semiconductor layer 123 is formed as a highly doped layer 1240. This highly doped layer 1240 facilitates the formation of an ohmic contact with the subsequent transparent conductive layer 140, thereby improving current diffusion. The depth of the recessed region 1241 is greater than the thickness of the highly doped layer 1240, thereby ensuring that there is no highly doped layer 1240 at the bottom of the recessed region 1241.

[0070] Similarly, refer to Figure 2 In this embodiment, a transparent insulating layer 130 is formed on the side of the current spreading layer 124 away from the second semiconductor layer 123. This transparent insulating layer 130 covers the bottom and sidewalls of the recessed region 1241. Further, referring to… Figure 2 and Figure 3 The transparent insulating layer 130 extends from the sidewall of the recessed region 1241 to the edge region of the platform region 1242, forming a first opening 131 above the platform region 1242. The thickness of the transparent insulating layer 130 is between Furthermore, given Further between The thickness of the transparent insulating layer is chosen to give it a certain reflective effect on light, thus increasing light output; on the other hand, unreflected light passes through the transparent insulating layer and enters the metal reflective layer, forming total internal reflection, which also increases light output.

[0071] The transparent insulating layer 130 can optionally be an insulating material layer with good light transmittance, such as an insulating oxide layer like MgF2, SiO2, Al2O3, or TiO2, or an insulating nitride layer like Si3N4. Preferably, in this embodiment, the transparent insulating layer 140 is a MgF2 layer with good light transmittance. There is a refractive index difference between the transparent insulating layer 130 and the semiconductor epitaxial stack 120. Therefore, when light radiated from the active layer 122 strikes the transparent insulating layer 130, a portion is reflected back to the semiconductor epitaxial stack 120, resulting in total internal reflection at the interface of the current spreading layer 124, the transparent insulating layer 130, and the semiconductor epitaxial stack. Furthermore, the transparent insulating layer 130 and the metal reflective layer 150 form a total internal reflection structure. The remaining portion of light that is not reflected and passes through the transparent insulating layer 130 is reflected by the metal reflective layer 150 until it exits from the light-emitting surface. Therefore, the transparent insulating layer 130 helps to improve the light extraction efficiency of the light-emitting diode 100.

[0072] Similarly, Figure 2 As shown, a transparent conductive layer 140 is formed on the side of the current spreading layer 124 away from the second semiconductor layer 123. The transparent conductive layer 140 covers the transparent insulating layer 130 above the current spreading layer 124 and the current spreading layer at the first opening 131, and forms an ohmic contact with the current spreading layer 124 (more specifically, the highly doped layer 1240) at the first opening 131, thereby facilitating current diffusion. The transparent conductive layer 140 completely fills the recessed region 1241, and is formed as a flat surface on the side away from the current spreading layer 124, for example, by polishing or etching.

[0073] The transparent conductive layer 140 is formed of a transparent conductive material, including, but not limited to, any one or more combinations of indium tin oxide (ITO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), zinc tin oxide (ZTO), gallium zinc oxide (GZO), indium tungsten oxide (IWO), zinc oxide (ZnO), gallium phosphide (GaP), indium cerium oxide (ICO), indium tungsten oxide (IWO), indium titanium oxide (ITiO), indium zinc oxide (IZO), indium gallium oxide (IGO), and gallium aluminum zinc oxide (GAZO). The transparent conductive layer 140 can be a single-layer structure formed from any one of the above materials, or a multilayer structure formed from any combination of the above materials.

[0074] In one optional embodiment of this example, such as Figure 3 As shown, the aforementioned transparent conductive layer 140 is a single-layer structure. Further, this single-layer structure is an indium zinc oxide (IZO) layer, and the thickness of the indium zinc oxide (IZO) layer is between... Further between Further between This thickness ensures good conductivity and current diffusion; on the other hand, it helps to fill the recessed areas in the current spreading layer, making it easier to form a flat surface through subsequent polishing or etching.

[0075] In another optional embodiment, the transparent conductive layer 140 is formed as a multilayer structure, with the transparent conductive layer 140 being a double-layer structure. Specifically, as shown... Figure 4 and Figure 5 As shown, the transparent conductive layer 140 includes a first sub-layer 141 and a second sub-layer 142, wherein the first sub-layer 141 is closer to the current spreading layer 124 (or the transparent insulating layer 130) than the second sub-layer 142. In an alternative example, such as... Figure 4 As shown, the first sublayer 141 covers the entire current spreading layer 124 on the side away from the second semiconductor layer 123, that is, it covers the current spreading layer 124 at the first opening 131 and the transparent insulating layer 130 above the current spreading layer 124. The second sublayer 142 covers the first sublayer 141 and is formed as a flat surface on the side away from the first sublayer 141. In another alternative example, such as... Figure 5 As shown, the first sublayer 141 is formed in the platform region 1242 at the first opening 131, and the second sublayer 142 covers the first sublayer 141 and the transparent insulating layer 130. Similarly, the side of the second sublayer 142 away from the first sublayer 141 is formed as a flat surface.

[0076] In an optional embodiment, the first sub-layer 141 is an indium tin oxide (ITO) layer to facilitate the formation of an ohmic contact with the current extension layer 124 of the platform region 1242; the second sub-layer 142 is an indium zinc oxide (IZO) layer, which fills the recessed region 1241 and completely covers the corresponding area of ​​the platform region 1242. A flat surface is formed by polishing or etching the second sub-layer 142. The thickness of the first sub-layer 141 is between... Furthermore, given The thickness of the second sublayer 142 is between Furthermore, given Or between The thickness settings of the first sublayer 141 and the second sublayer 142 are conducive to minimizing light absorption while ensuring that the first sublayer 141 forms an ohmic contact with the current spreading layer 124, and at the same time ensuring that the side of the second sublayer 142 away from the first sublayer 141 can form a flat surface through polishing, etching and other means.

[0077] Refer again Figure 2A metal reflective layer 150 is formed on the side of the transparent conductive layer 140 away from the current spreading layer 124. That is, the metal reflective layer 150 covers the flat surface of the transparent conductive layer 140. In an optional embodiment, the metal reflective layer 150 is preferably an Ag mirror. Since it is formed on a flat surface, the surface of the metal reflective layer 150 is also a flat surface. This flat surface helps to improve the continuity and flatness of the metal reflective layer 150, and there will be no defects such as breaks or voids, so that the metal reflective layer 150 forms a specular reflection, improving its reflection efficiency. At the same time, the metal reflective layer 150 and the transparent insulating layer 130 can form a total internal reflection structure, further improving the light reflection efficiency.

[0078] Refer again Figure 2 The light-emitting diode 100 in this embodiment further includes an electrode structure, which includes a first electrode 125 formed on the light-emitting surface and electrically connected to the first semiconductor layer 121, and a second electrode 126 located on the side of the substrate 110 away from the semiconductor epitaxial stack 120 and electrically connected to the second semiconductor layer 123. Optionally, an N-type ohmic contact layer is provided between the first electrode 125 and the first semiconductor layer 121. Further, as... Figure 2 and Figure 4 As shown, the first electrode 25 has a pad 1251 and an extension 1252 connected to the pad 1251. The extension 1252 extends from the pad 1251 to other areas of the light-emitting surface to improve the current diffusion effect and uniformity on one side of the first semiconductor layer 121. In an optional embodiment, the extension 1252 is formed as a finger-shaped extension 1252, and the first electrode 125 may include one or more of the extensions 1252.

[0079] In alternative embodiments, the same applies. Figure 2 and Figure 6 As shown, in the stacking direction of the semiconductor epitaxial stack 120, the aforementioned pad 1251 corresponds to the recessed region 1241 of the current spreading layer 124. That is, as Figure 6 As shown, in the top view of the light-emitting diode 100, the projection of the pad 1251 falls within the projection range of the recess 1241. Furthermore, the aforementioned transparent insulating layer 130 is not formed in the region of the recess 1241 corresponding to the pad 1251. That is, as... Figure 2 As shown, the transparent insulating layer 130 forms a second opening 132 in the area corresponding to the pad 1251. And as... Figure 6As shown, the projected outline of pad 1251 lies within the projected outline of transparent insulating layer 130, meaning the projection of pad 1251 falls within the projection range of second opening 132. Since transparent insulating layer 130, especially when it is a MgF2 layer, has poor adhesion to transparent conductive layer 140, the above arrangement can prevent the transparent insulating layer 130 from peeling off from the transparent conductive layer 140 during subsequent wire bonding, thereby improving the reliability of light-emitting diode 100.

[0080] The substrate 110 described above can be an insulating substrate, a semiconductor substrate, a metal substrate, etc. In this embodiment, the substrate 110 is a silicon (Si) substrate, a germanium (Ge) substrate, a silicon carbide (SiC) substrate, a gallium nitride (GaN) substrate, an aluminum nitride (AlN) substrate, a gallium phosphide (GaP) substrate, or a gallium arsenide (GaAs) substrate, etc. Figure 2 As shown, a bonding metal layer 160 is formed between the semiconductor epitaxial stack 120 of the light-emitting diode 100 and the substrate 110. Further, the metal bonding layer 160 is located between the metal reflective layer 150 and the substrate 110, and the metal bonding layer 160 bonds the semiconductor epitaxial stack 120 and the substrate 110 together. Optionally, the metal bonding layer 160 can be one or a combination of Cu, Al, Sn, Au, Pb, Ti, Ni, In, Pt, or W.

[0081] Reference Figure 2 In order to further increase the light extraction efficiency of the light-emitting diode 100, in this embodiment, after the first electrode 125 is formed, the light-emitting surface outside the area covered by the first electrode 125 is roughened to form a roughened surface, thereby increasing the light extraction rate.

[0082] Similarly, refer to Figure 2 An insulating protective layer 170 is formed on the exposed sidewall of the light-emitting diode 100 to protect the light-emitting diode from damage by external moisture and impurities, thereby improving the reliability of the light-emitting diode. This insulating protective layer 170 can be made of materials such as SiO2, Si3N4, Al2O3, TiO2, ZnO, or HfO2.

[0083] Example 2

[0084] This embodiment provides a light-emitting device, such as... Figure 7 As shown, the light-emitting device 200 includes a circuit board 201 and at least one light-emitting unit 202 fixed to the circuit board 201. The light-emitting unit 202 includes the light-emitting diode provided in Embodiment 1 of this application. Because the light-emitting device includes the light-emitting diode provided in Embodiment 1, it has good light extraction efficiency and better reliability.

[0085] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A light-emitting diode, characterized in that, At least including: A semiconductor epitaxial stack includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially, and a current spreading layer located on the side of the second semiconductor layer away from the active layer; the current spreading layer has a plateau region and a recessed region surrounding the plateau region, the recessed region being recessed toward the first semiconductor layer; A transparent insulating layer covers the side of the current spreading layer away from the second semiconductor layer, and the transparent insulating layer does not completely cover the plateau region; A transparent conductive layer is located on the side of the current spreading layer away from the second semiconductor layer, and covers the transparent insulating layer and the platform region not covered by the transparent insulating layer. The side of the transparent conductive layer away from the current spreading layer is formed as a flat surface. A metallic reflective layer covers the flat surface of the transparent conductive layer; A substrate having a front side and a back side disposed opposite to each other, wherein the metal reflective layer is located on the front side of the substrate.

2. The light-emitting diode according to claim 1, characterized in that, The thickness of the transparent insulating layer is between 3. The light-emitting diode according to claim 1, characterized in that, The material forming the transparent insulating layer includes any one or more of magnesium fluoride, insulating oxides, and insulating nitrides.

4. The light-emitting diode according to claim 1, characterized in that, The thickness of the transparent conductive layer is between 5. The light-emitting diode according to claim 1, characterized in that, The transparent conductive layer includes one or a combination of indium tin oxide, indium zinc oxide, zinc oxide, and indium gallium oxide.

6. The light-emitting diode according to claim 5, characterized in that, The transparent conductive layer can be a single-layer structure or a multi-layer structure.

7. The light-emitting diode according to claim 1, characterized in that, The transparent conductive layer includes an indium tin oxide layer and an indium zinc oxide layer, the indium tin oxide layer being formed in the platform region, and the indium zinc oxide layer covering the indium tin oxide layer and the recessed region.

8. The light-emitting diode according to claim 7, characterized in that, The thickness of the indium tin oxide layer is between 9. The light-emitting diode according to claim 1, characterized in that, It also includes an electrode structure, which comprises: A first electrode is formed above the first semiconductor layer, including a pad and an extension connected to the pad, and is projected on the plane where the light-emitting surface is located, wherein the projection of the pad is located within the projection range of the recessed area. The second electrode is formed on the back side of the substrate and is electrically connected to the second semiconductor layer.

10. The light-emitting diode according to claim 9, characterized in that, In the stacking direction of the semiconductor epitaxial stack, the transparent insulating layer is not disposed in the current spreading layer region corresponding to the pad of the first electrode.

11. The light-emitting diode according to claim 9, characterized in that, The projection of the pads onto the plane containing the front side of the substrate does not overlap with the projection of the transparent insulating layer.

12. The light-emitting diode according to claim 1, characterized in that, The surface layer of the plateau region of the current spreading layer is a highly doped layer, forming an ohmic contact with the transparent conductive layer.

13. The light-emitting diode according to claim 1, characterized in that, The depth of the recessed region is less than and less than or equal to the thickness of the current spreading layer.

14. The light-emitting diode according to claim 1, characterized in that, The substrate and the metal reflective layer also include a metal bonding layer.

15. The light-emitting diode according to claim 1, characterized in that, The angle between the sidewall of the recessed area and the bottom of the recessed area is between 110° and 130°.

16. The light-emitting diode according to claim 15, characterized in that, The transparent insulating layer extends from the bottom and sidewalls of the recess to the outer periphery of the platform area, forming a first opening in the middle region of the platform area.

17. A light-emitting device, characterized in that, It includes a circuit board and a light-emitting element disposed on the circuit board, wherein the light-emitting element comprises a light-emitting diode as described in any one of claims 1 to 16.

Images