Light emitting diode and light emitting device

Abstract

The present invention provides a light emitting diode, which comprises an epitaxial structure, a first electrode and a second electrode. The epitaxial structure has a first surface and a second surface opposite to each other. The epitaxial structure comprises an N-type GaP current expansion layer, an N-type semiconductor layer, a light emitting layer, a P-type semiconductor layer and an ohmic contact layer in sequence from the first surface to the second surface. The first electrode and the second electrode are electrically connected to the N-type GaP current expansion layer and the ohmic contact layer, respectively. The material of the ohmic contact layer comprises Al x Ga (1‑x) As, 0<x≤0.6. By this setting, the red light absorption problem of the ohmic contact layer can be improved and the light extraction efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a light emitting diode and a light emitting device. Background Art

[0002] Light Emitting Diode (LED) is a semiconductor light-emitting element, usually made of semiconductors such as GaN, GaAs, GaP, GaAsP, etc. Its core is a PN junction with light-emitting characteristics. Under forward voltage, electrons are injected from the N region into the P region, and holes are injected from the P region into the N region. Some of the minority carriers that enter the other region recombine with the majority carriers to emit light. LED has the advantages of high luminous intensity, high efficiency, small size, and long service life, and is considered to be one of the most promising light sources at present.

[0003] like Figure 1 As shown, the existing light emitting diode 10 includes a substrate 100, a P-type current spreading layer 102, a P-type semiconductor layer 104, a light emitting layer 106, an N-type semiconductor layer 108, an N-type current spreading layer 110, an ohmic contact layer 112 (located only below the electrode), and an N-electrode 114, which are stacked in sequence from bottom to top. The N-type current spreading layer 110 is AlGaInP. A P-electrode 116 is disposed on the P-type current spreading layer 102. The existing light-emitting diode 10 has the following problems: 1. In order to ensure good ohmic contact on the N side, GaAs is usually used as the ohmic contact layer. GaAs absorbs red light, which not only affects the light extraction efficiency, but also increases the wet etching process, resulting in a more complicated process and increased cost; 2. In order to ensure a good current spreading effect on the N side, the N-type current spreading layer 110 will grow thicker (the grown AlGaInP layer is thicker, with a thickness greater than 3um), so that after the mesa etching, the height difference between the N electrode 114 and the P electrode 116 is large, which increases the difficulty of the subsequent process.

[0004] In addition, if Figure 2 As shown, in order to obtain better ESD resistance and current expansion effect, the existing light-emitting diode 10 will extend the shape of the N electrode 114. Especially for small-sized chips (such as Mini LED), the finger part extending from the electrode will cross the middle area of ​​the semiconductor layer, and there is a possibility that the pin will hit the finger, increasing the risk of epitaxy being cracked. Summary of the invention

[0005] The invention provides a light emitting diode, which comprises an epitaxial structure, a first electrode and a second electrode.

[0006] The epitaxial structure has a first surface and a second surface opposite to each other. The epitaxial structure includes an N-type GaP current spreading layer, an N-type semiconductor layer, a light-emitting layer, a P-type semiconductor layer and an ohmic contact layer in sequence from the first surface to the second surface. The first electrode and the second electrode are electrically connected to the N-type GaP current spreading layer and the ohmic contact layer, respectively, wherein the material of the ohmic contact layer includes Al x Ga （1-x） As, 0<x≤0.6.

[0007] In one embodiment, the value range of x is 0.5<x≤0.6.

[0008] In one embodiment, the light emitting diode further includes a transparent conductive layer, and the transparent conductive layer is located between the ohmic contact layer and the second electrode.

[0009] In one embodiment, the thickness of the transparent conductive layer is in the range of 200-500 angstroms.

[0010] In one embodiment, the material of the transparent conductive layer may include one or more of indium tin oxide, zinc indium oxide, indium oxide, tin oxide, cadmium tin oxide, tin antimony oxide, aluminum zinc oxide, zinc tin oxide, zinc oxide doped with gallium, indium oxide doped with tungsten or zinc oxide.

[0011] In one embodiment, the epitaxial structure further includes a transition layer located between the P-type semiconductor layer and the ohmic contact layer.

[0012] In one embodiment, the material of the transition layer includes AlGaInP.

[0013] In one embodiment, there is a height difference between the first electrode and the second electrode, and the height difference is less than or equal to 3 μm.

[0014] In one embodiment, the light emitting diode further includes an insulating layer, which covers the substrate, the epitaxial structure, the first electrode and the second electrode, and has a first opening and a second opening, wherein the first opening is located above the first electrode and the second opening is located above the second electrode.

[0015] In one embodiment, the second electrode includes a starting electrode and an extension electrode, the extension electrode is connected to the starting electrode, and the extension electrode extends from the starting electrode toward the first electrode.

[0016] In one embodiment, when looking down from above the light-emitting diode toward the epitaxial structure, there is a first shortest distance between the extended electrode and the first electrode, and the first shortest distance is greater than or equal to 1 / 2 of the length of the epitaxial structure.

[0017] In one embodiment, looking down from above the light-emitting diode toward the epitaxial structure, the ratio of the length of the extended electrode to the length of the light-emitting diode structure is between 1:20 and 1:3, and the ratio of the width of the extended electrode to the width of the epitaxial structure is between 1:2 and 9:10.

[0018] In one embodiment, the size of the light emitting diode is less than 300 μm.

[0019] In one embodiment, the light emitting diode radiates red light.

[0020] In one embodiment, the first electrode and the second electrode of the light emitting diode are located on the same side of the epitaxial structure.

[0021] The present invention also provides a light emitting device, which adopts any of the light emitting diodes described above.

[0022] An advantage of the present invention is to provide a light emitting diode and a light emitting device, using Al x Ga （1-x） The As material forms an ohmic contact layer to prevent the ohmic contact layer from absorbing red light and affecting the overall light-emitting effect.

[0023] Another advantage of the present invention is to provide a light-emitting diode and a light-emitting device, which achieves a current spreading effect by setting a transparent conductive layer with an ohmic contact layer, thereby reducing the height difference of the light-emitting diode table and simplifying the process. In addition, since the transparent conductive layer has an excellent current spreading effect, the electrode does not need to be designed with a longer electrode finger for current spreading, that is, the electrode size and area can be reduced, the cost can be reduced, the electrode shading area can be reduced, the light-emitting brightness can be improved, and the pin can be prevented from breaking the epitaxial.

[0024] Other features and beneficial effects of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other beneficial effects of the present invention can be achieved and obtained by the structures specifically pointed out in the description, claims, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The positional relationships described in the drawings in the following description are based on the directions in which the components are drawn in the diagrams, unless otherwise specified.

[0026] Figure 1It is a schematic diagram of the structure of an existing light emitting diode;

[0027] Figure 2 is a top view schematic diagram of an existing light emitting diode;

[0028] Figure 3 is a schematic structural diagram of a light emitting diode provided by an embodiment of the present invention;

[0029] Figure 4 is a schematic top view of a light emitting diode provided by an embodiment of the present invention;

[0030] Figures 5 to 7 It is a schematic diagram of the structure of the epitaxial structure at various stages in the manufacturing process.

[0031] Reference numerals:

[0032] 20-light-emitting diode; 22-substrate; 23-bonding layer; 24-epitaxial structure; 241-N-type semiconductor layer; 242-light-emitting layer; 243-P-type semiconductor layer; 244-first surface; 245-second surface; 25-transition layer; 26-N-type GaP current spreading layer; 28-ohmic contact layer; 30-transparent conductive layer; 32-insulating layer; 321-first opening; 322-second opening; 34-first electrode; 36-second electrode; H1-thickness of transparent conductive layer; H2-height difference; L1-length of light-emitting diode; L2-length of extended electrode; W1-width of light-emitting diode; W2-width of extended electrode; S-first shortest distance. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be understood that the terms "center", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In addition, the term "including" and any variation thereof all mean "at least including".

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integrally formed connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] See also Figure 3 , Figure 3 2 is a schematic diagram of a light emitting diode 20 provided in an embodiment of the present invention. To achieve at least one of the above advantages or other advantages, an embodiment of the present invention provides a light emitting diode 20. The light emitting diode 20 includes an epitaxial structure 24, a first electrode 34 and a second electrode 36.

[0037] The epitaxial structure 24 is disposed on the upper surface of the substrate 22 through the bonding layer 23. In this embodiment, the substrate 22 is a sapphire substrate. Further, the substrate 22 can be a transparent substrate, and the material of the transparent substrate includes inorganic materials or III-V semiconductor materials. Inorganic materials include silicon carbide (SiC), germanium (Ge), sapphire (sapphire), lithium aluminate (LiAlO 2), zinc oxide (ZnO), glass or quartz. III-V semiconductor materials include indium phosphide (InP), gallium phosphide (GaP), gallium nitride (GaN), and aluminum nitride (AlN) materials. The substrate 22 has sufficient strength to mechanically support the epitaxial structure 24 and can transmit light emitted from the epitaxial structure 24. The thickness of the substrate 22 is preferably greater than 50μm. In addition, in order to facilitate mechanical processing of the substrate 22 after bonding to the epitaxial structure 24, the thickness is preferably not more than 300μm.

[0038] The material of the bonding layer 23 may be an insulating material and / or a conductive material. The insulating material includes but is not limited to polyimide (PI), benzocyclobutene (BCB), perfluorocyclobutane (PFCB), magnesium oxide (MgO), Su8, epoxy resin, acrylic resin, cycloolefin polymer (COC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyetherimide, fluorocarbon polymer, glass, aluminum oxide (Al 2 O 3 ), silicon oxide (SiO x ), titanium oxide (TiO 2 ), Tantalum Oxide (Ta 2 O 5 ), Silicon Nitride (SiN x ) or spin-on glass (SOG). Conductive materials include but are not limited to 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), zinc oxide (ZnO), indium zinc oxide (IZO), diamond-like carbon film (DLC) or gallium zinc oxide (GZO), etc.

[0039] In some embodiments, the second surface 244 of the epitaxial structure 24 close to the substrate 22 may be a roughened surface. When the light emitted by the light emitting layer 242 passes through the bonding layer 23 and the second surface 244 , the occurrence of total reflection can be reduced, thereby improving the light emitting performance of the light emitting diode 20 .

[0040] The epitaxial structure 24 has a first surface 244 and a second surface 245 opposite to each other, and includes an N-type GaP current spreading layer 26 , an N-type semiconductor layer 241 , a light emitting layer 242 , a P-type semiconductor layer 243 and an ohmic contact layer 28 in sequence from the first surface 244 to the second surface 245 .

[0041] The N-type GaP current spreading layer 26 is arranged on the substrate 22 to perform current spreading and improve the light-emitting effect. The N-type semiconductor layer 241 is arranged on the N-type GaP current spreading layer 26, which may include an N-type capping layer and an N-type limiting layer from bottom to top. The material of the N-type limiting layer may include AlGaInP with a thickness of 500-1000A (angstroms), which is used to limit the doped ions in the N-type capping layer from entering the light-emitting area. The material of the N-type capping layer may include AlINP doped with Si with a thickness of 2000-6000A for providing electrons.

[0042] The light-emitting layer 242 is disposed on the N-type semiconductor layer 241 and may be a quantum well structure (Quantum Well, referred to as QW). In some embodiments, the light-emitting layer 242 may also be a multiple quantum well structure (Multiple Quantum Well, referred to as MQW), wherein the multiple quantum well structure includes multiple quantum well layers (Well) and multiple quantum barrier layers (Barrier) alternately disposed in a repeated manner. In addition, the composition and thickness of the well layer in the light-emitting layer 242 determine the wavelength of the generated light. In this embodiment, the light emitted by the light-emitting layer 242 is red light, and the material of the light-emitting layer 242 includes AlGaInP. That is, the light-emitting diode 20 radiates red light, and the light-emitting diode 20 is a red light diode.

[0043] The P-type semiconductor layer 243 is disposed on the light-emitting layer 242, and may include a P-type confinement layer and a P-type capping layer from bottom to top. The material of the P-type capping layer may include AlINP doped with Mg, with a thickness of 4000-6000A, for providing holes. The material of the P-type confinement layer may include AlGaInP, with a thickness of 500-1000A, for limiting the doped ions in the P-type capping layer from entering the light-emitting region.

[0044] The ohmic contact layer 28 is located on the P-type semiconductor layer 243. The material of the ohmic contact layer 28 includes Al x Ga （1-x） As, 0<x≤0.6. x Ga （1-x） As has the property that it hardly absorbs light for the AlGaInP red light diode, so as to improve the light-emitting effect and light-extraction efficiency of the light-emitting diode 20. Preferably, in order to prevent the ohmic contact layer 28 from absorbing red light, the bandgap width of the ohmic contact layer 28 needs to be increased, that is, the peak wavelength corresponding to the ohmic contact layer 28 needs to be reduced, and considering that too high Al content may cause the subsequent transparent conductive layer 30 to affect the ohmic contact layer 28 during the etching process, therefore, x is preferably between 0.5-0.6, that is, 0.5<x≤0.6.

[0045] The first electrode 34 is located on the N-type GaP current spreading layer 26, and the second electrode 36 is located on the ohmic contact layer 28. The first electrode 34 and the second electrode 36 are electrically connected to the N-type GaP current spreading layer 26 and the ohmic contact layer 28, respectively. There is a height difference H2 between the first electrode 34 and the second electrode 36, and the height difference H2 is less than or equal to 3μm, which reduces the difficulty of the process. Specifically, the light-emitting diode 20 also includes a transparent conductive layer 30. The transparent conductive layer 30 is located between the ohmic contact layer 28 and the second electrode 36, and is used to expand the current, so that the current distribution is more uniform, and the light-emitting performance of the light-emitting diode 20 is improved. By using the transparent conductive layer 30 in combination with the ohmic contact layer 28, compared with the existing light-emitting diode, there is no need to form a thicker N-type current spreading layer 110, so as to achieve the purpose of reducing the height difference of the table and simplify the process. Preferably, the thickness H1 of the transparent conductive layer 30 ranges from 200 to 500 angstroms.

[0046] The transparent conductive layer 30 may be made of a transparent conductive material. By using the transparent conductive layer 30 of a conductive oxide, the reliability of the light emitting diode 20 chip can be improved. As an example, the transparent conductive material may include one or more of indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), zinc tin oxide (ZTO), gallium doped zinc oxide (GZO), tungsten doped indium oxide (IWO) or zinc oxide (ZnO), but the embodiments of the present disclosure are not limited thereto.

[0047] In one embodiment, if Figure 3 As shown, the epitaxial structure 24 further includes a transition layer 25. The light emitting diode 20 further includes an insulating layer 32.

[0048] The transition layer 25 is located between the P-type semiconductor layer 243 and the ohmic contact layer 28. The material of the transition layer 25 includes AlGaInP to play the role of a transition layer and reduce the generation of defects caused by lattice mismatch between the P-type semiconductor layer 243 and the ohmic contact layer 28. The thickness of the transition layer 25 ranges from 0.1 to 0.6 μm.

[0049] The insulating layer 32 covers the substrate 22, the epitaxial structure 24, the first electrode 34 and the second electrode 36, and has a first opening 321 and a second opening 322. The first opening 321 is located above the first electrode 34, and the second opening 322 is located above the second electrode 36, so as to facilitate the subsequent use of the light-emitting diode 20. The insulating layer 32 has different functions according to the position involved. For example, covering the side wall of the epitaxial structure 24 can prevent the conductive material from leaking and electrically connecting the N-type semiconductor layer 241 and the P-type semiconductor layer 243, thereby reducing the short circuit anomaly of the light-emitting diode 20, but the embodiment of the present disclosure is not limited to this. The material of the insulating layer 32 includes a non-conductive material. The non-conductive material is preferably an inorganic material or a dielectric material. The inorganic material may include silica gel. The dielectric material includes aluminum oxide (AlO), silicon nitride (SiNx), silicon oxide (SiOx), titanium oxide (TiOx), or magnesium fluoride (MgFx) which may be an electrical insulating material. For example, the insulating layer 32 may be silicon dioxide, silicon nitride, titanium oxide, tantalum oxide, niobium oxide, barium titanate, or a combination thereof. The combination thereof may be, for example, a Bragg reflector (DBR) formed by repeatedly stacking two materials.

[0050] In one embodiment, if Figure 4 As shown, the second electrode 36 includes a starting electrode 362 and an extension electrode 364. The extension electrode 364 is connected to the starting electrode 362, and the extension electrode 364 extends from the starting electrode 362 toward the first electrode 34. The provision of the extension electrode 364 can further enhance the current spreading effect.

[0051] Looking down from the top of the light emitting diode 20 toward the epitaxial structure 24, Figure 4 As shown, there is a first shortest distance S between the extended electrode 364 and the first electrode 34, and the first shortest distance S is greater than or equal to 1 / 2 of the length L1 of the light-emitting diode 20. In other words, the second electrode 36 and the first electrode 34 both avoid the middle area of ​​the light-emitting diode 20 to prevent the pin from hitting the electrode and reduce the risk of breaking the epitaxy. Compared with the first electrode 34, the second electrode 36 is biased towards the left end of the light-emitting diode 20, and the first electrode 34 is biased towards the right end of the light-emitting diode 20. The ratio of the length L2 of the extended electrode 364 to the length L1 of the light-emitting diode 20 is between 1:20 and 1:3, and the ratio of the width W2 of the extended electrode 364 to the width W1 of the epitaxial structure 24 is between 1:2 and 9:10. With the excellent current spreading effect of the transparent conductive layer 30, the second electrode 36 does not need to be designed with a longer electrode finger for current spreading, that is, the size and area of ​​the electrode can be controlled within the above range, avoiding the middle area, preventing the pin from hitting the electrode, and reducing the risk of epitaxy being broken.

[0052] In one embodiment, the LED 20 may be a small-sized LED. Specifically, the size of the LED 20 may be less than 300 μm, that is, the length and width of the LED 20 are both less than or equal to 300 μm.

[0053] See also Figures 5 to 7 , Figures 5 to 7 Schematic diagram of the structure of the epitaxial structure 24 at various stages during the manufacturing process.

[0054] Reference Figure 5 First, a buffer layer 52 and an etching stop layer 54 are sequentially grown on the epitaxial growth substrate 50. The buffer layer 52 may be gallium arsenide, and the etching stop layer 54 is used for removing the epitaxial growth substrate 50 later.

[0055] Next, refer to Figure 6 , continue to grow the semiconductor light-emitting sequence, that is, grow the ohmic contact layer 28, the transition layer 25, the P-type semiconductor layer 243, the light-emitting layer 242, the N-type semiconductor layer 241 and the N-type GaP current spreading layer 26 in sequence on the etching stop layer 54.

[0056] Follow-up, see Figure 7 , the semiconductor light emitting sequence is transferred to the substrate 22 of this embodiment through the bonding layer 23 to form an epitaxial structure 24 with the N-type semiconductor layer 241 at the bottom and the P-type semiconductor layer 243 at the top. Figure 6 The etching stop layer 54 in the semiconductor light emitting sequence is cut off from the epitaxial growth substrate 50, and then the semiconductor light emitting sequence is connected to the substrate 22 through the bonding layer 23. In addition, the ohmic contact layer 28 is etched toward the N-type GaP current spreading layer 26 to expose the N-type GaP current spreading layer 26 for setting the first electrode 34.

[0057] This embodiment further provides a light emitting device, which uses the light emitting diode 20 provided in any of the above embodiments, and its specific structure and technical effects are not described in detail.

[0058] In summary, an advantage of the present invention is to provide a light emitting diode 20 and a light emitting device, using AlxGa(1-x)As material to form an ohmic contact layer 28, thereby preventing the ohmic contact layer 28 from absorbing red light and affecting the overall light emitting effect.

[0059] Another advantage of the present invention is to provide a light emitting diode 20 and a light emitting device, which achieves a current spreading effect by providing a transparent conductive layer 30 with an ohmic contact layer 28, thereby reducing the height difference of the table of the light emitting diode 20 and simplifying the process. In addition, since the transparent conductive layer 30 has an excellent current spreading effect, the electrode does not need to be designed with a longer electrode finger for current spreading, that is, the electrode size and area can be reduced, the cost can be reduced, and the pin can be prevented from hitting the electrode, thereby reducing the risk of the electrode being cracked.

[0060] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, without having to solve all the technical problems listed in the prior art or background technology at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation on the claim.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light emitting diode, characterized in that: The light emitting diode comprises: An epitaxial structure having a first surface and a second surface opposite to each other, wherein the epitaxial structure includes, from the first surface to the second surface, an N-type GaP current spreading layer, an N-type semiconductor layer, a light emitting layer, a P-type semiconductor layer and an ohmic contact layer; A first electrode electrically connected to the N-type GaP current spreading layer; a second electrode, electrically connected to the ohmic contact layer; Wherein, the material of the ohmic contact layer includes Al x Ga (1-x) As, the value range of x is 0.5<x≤0.

6.

2. The light emitting diode according to claim 1, characterized in that: The light emitting diode further includes a transparent conductive layer, and the transparent conductive layer is located between the ohmic contact layer and the second electrode.

3. The light emitting diode according to claim 2, characterized in that: The thickness of the transparent conductive layer is in the range of 200-500 angstroms.

4. The light emitting diode according to claim 2, characterized in that: The material of the transparent conductive layer may include one or more of indium tin oxide, zinc indium oxide, indium oxide, tin oxide, cadmium tin oxide, tin antimony oxide, aluminum zinc oxide, zinc tin oxide, zinc oxide doped with gallium, indium oxide doped with tungsten or zinc oxide.

5. The light emitting diode according to claim 1, characterized in that: The epitaxial structure further includes a transition layer located between the P-type semiconductor layer and the ohmic contact layer.

6. The light emitting diode according to claim 5, characterized in that: The material of the transition layer includes AlGaInP.

7. The light emitting diode according to claim 1, characterized in that: There is a height difference between the first electrode and the second electrode, and the height difference is less than or equal to 3 μm.

8. The light emitting diode according to claim 1, characterized in that: The light emitting diode further includes an insulating layer, which covers the epitaxial structure, the first electrode and the second electrode and has a first opening and a second opening, wherein the first opening is located above the first electrode and the second opening is located above the second electrode.

9. The light emitting diode according to claim 1, characterized in that: The second electrode includes a starting electrode and an extension electrode. The extension electrode is connected to the starting electrode. The extension electrode extends from the starting electrode toward the first electrode.

10. The light emitting diode according to claim 9, characterized in that: Looking down from above the light-emitting diode toward the epitaxial structure, there is a first shortest distance between the extended electrode and the first electrode, and the first shortest distance is greater than or equal to 1 / 2 of the length of the light-emitting diode.

11. The light emitting diode according to claim 9, characterized in that: Looking down from above the light emitting diode toward the epitaxial structure, the ratio of the length of the extended electrode to the length of the light emitting diode is between 1:20 and 1:3, and the ratio of the width of the extended electrode to the width of the light emitting diode is between 1:2 and 9:

10.

12. The light emitting diode according to claim 1, characterized in that: The size of the light emitting diode is less than 300 μm.

13. The light emitting diode according to claim 1, characterized in that: The light emitting diode radiates red light.

14. The light emitting diode according to claim 1, characterized in that: The first electrode and the second electrode are located on a same side of the epitaxial structure.

15. A light emitting device, characterized in that: A light emitting diode as claimed in any one of claims 1 to 14 is used.

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