Light emitting diode and light emitting device

Abstract

The invention provides a light-emitting diode and a light-emitting device. The light-emitting diode comprises a first electrode formed on a light-emitting surface and an insulating reflecting layer arranged around the first electrode. When light emitted from the semiconductor epitaxial laminated layer faces the direction of the first electrode, the insulating reflecting layer can reflect the part of light, one part of the reflected light can be directly emitted, the other part of the reflected light can be possibly reflected back to the semiconductor epitaxial laminated layer, and the light is finally emitted from the light emitting surface after being reflected again. Visibly, due to the arrangement of the insulating reflecting layer, the light absorbed by the metal electrode is reduced, and the light emitting quantity on the light emitting surface is increased. Therefore, the insulating reflecting layer can improve the luminous efficiency of the light-emitting diode and improve the brightness of the light-emitting diode. Therefore, the brightness and luminous efficiency of the light-emitting device comprising the light-emitting diode can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices and apparatuses, and particularly to a light-emitting diode and a light-emitting device. Background Art

[0002] A light-emitting diode (LED) has advantages such as high luminous intensity, high efficiency, small size, and long service life, and is considered to be one of the most potential light sources at present. In recent years, LEDs have been widely used in daily life, such as in the fields of lighting, signal display, backlight, vehicle lamps, and large-screen display. At the same time, these applications also put forward higher requirements for the brightness and luminous efficiency of LEDs.

[0003] A light-emitting diode realizes at least providing electrons or holes respectively through n-type doping or p-type doping of a first-type semiconductor layer and a second-type semiconductor layer, and electrons and holes radiatively recombine and emit light in an active layer. For the convenience of backend packaging, metal electrodes are usually provided on the N side and P side of the light-emitting diode, and the metal electrodes usually have a certain thickness. Since metal materials have light-absorbing properties, a part of the light emitted from the epitaxial layer of the light-emitting diode will be incident on the metal electrode and absorbed by the metal electrode, thus affecting the light extraction effect of the light-emitting diode and further affecting its brightness. Summary of the Invention

[0004] In view of the deficiencies in the light extraction rate of light-emitting diodes in the prior art, the present invention provides a light-emitting diode and a light-emitting device to solve one or more of the above problems.

[0005] An embodiment of the present application provides a light-emitting diode, which at least includes:

[0006] A semiconductor epitaxial stack, including a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence, and a side of the first semiconductor layer away from the active layer is an out-light surface of the light-emitting diode;

[0007] An electrode structure, including a first electrode located on the out-light surface and electrically connected to the first semiconductor layer;

[0008] An insulating reflective layer, which is disposed at an interval between the out-light surface and the first electrode, the insulating reflective layer surrounds the first electrode to form a closed structure, and in the plane where the out-light surface is located, the projection of the first electrode is within the projection range of the insulating reflective layer.

[0009] Another embodiment of the present application provides a light-emitting device, which includes a circuit board and a light-emitting element disposed on the circuit board, and the light-emitting element includes the light-emitting diode provided by the present application.

[0010] As described above, the light-emitting diode and the light-emitting device of the present application have the following beneficial effects:

[0011] The light-emitting diode of the present application includes a first electrode formed on the light-emitting surface and an insulating reflective layer disposed around the first electrode. When the light emitted from the semiconductor epitaxial stack is directed towards the first electrode, the insulating reflective layer can reflect this part of the light. A part of the reflected light can be directly emitted, and another part may be reflected back to the semiconductor epitaxial stack and finally emitted from the light-emitting surface after being reflected again. It can be seen that the setting of the insulating reflective layer reduces the light absorbed by the metal electrode and increases the light output on the light-emitting surface. Therefore, the above-mentioned insulating reflective layer can improve the light extraction efficiency of the light-emitting diode and increase its brightness. Furthermore, it can improve the brightness and light-emitting efficiency of the light-emitting device including the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Shows a schematic structural diagram of a light-emitting diode in the prior art.

[0013] Figure 2 Shows a top-view structural diagram of the light-emitting diode provided in Embodiment 1 of the present invention.

[0014] Figure 3 Shows Figure 2 A schematic cross-sectional structural diagram of the shown light-emitting diode along the A-A direction.

[0015] Figure 4 Shows Figure 2 An SEM image of the shown light-emitting diode.

[0016] Figure 5 Shows a schematic structural diagram of the light-emitting device provided in Embodiment 2 of the present invention.

[0017] DESCRIPTION OF REFERENCE NUMERALS

[0018] 10. Light-emitting diode; 11. N-type semiconductor layer; 12. Active layer; 13. P-type semiconductor layer; 14. N electrode;

[0019] 100. Light-emitting diode; 110. Semiconductor epitaxial stack; 111. First semiconductor layer; 112. Active layer; 113. Second semiconductor layer; 120. Dielectric layer; 121. Through hole; 130. Metal reflective layer; 140. Substrate; 151. First electrode; 1511. Pad area, 1512. Extension bar; 152. Second electrode; 153. N-type ohmic contact layer; 160. Insulating reflective layer; 170. Insulating protective layer; 180. Bonding layer;

[0020] 200. Light-emitting device; 201. Circuit board; 202. Light-emitting diode. DETAILED DESCRIPTION OF THE INVENTION

[0021] The embodiments of the present invention will be described below through specific examples, and those skilled in the art can easily understand the 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 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.

[0022] As Figure 1 shown, in the prior art, a vertical - structure light - emitting diode 10 includes an N - type semiconductor layer, an active layer, and a P - type semiconductor layer stacked in sequence from top to bottom. The side of the N - type semiconductor layer away from the active layer is the light - emitting surface, and an N - electrode is formed thereon. This N - electrode is usually a metal electrode, such as Au, AuGeNi, Ge, Ni, Pt, Pd, etc. This metal electrode has a certain light - absorbing effect and will absorb the light radiated by the active layer, resulting in a reduction in the light emitted from the light - emitting surface, affecting the light - emitting efficiency and brightness of the light - emitting diode.

[0023] In view of the problem of the reduced brightness of the light - emitting diode caused by the light absorption of the metal electrode in the prior art, an embodiment of the present application provides a light - emitting diode, which at least includes:

[0024] A semiconductor epitaxial stack, including a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence. The side of the first semiconductor layer away from the active layer is the light - emitting surface of the light - emitting diode;

[0025] An electrode structure, including a first electrode located on the light - emitting surface and electrically connected to the first semiconductor layer;

[0026] An insulating reflection layer, disposed at an interval between the light - emitting surface and the first electrode. The insulating reflection layer surrounds the first electrode to form a closed - type structure, and in the projection on the plane where the light - emitting surface is located, the projection of the first electrode is within the projection range of the insulating reflection layer.

[0027] A part of the light emitted from the semiconductor epitaxial stack is directed towards the first - electrode direction. The above - mentioned insulating reflection layer is arranged around the first electrode, so it can reflect this part of the light. A part of the reflected light can be directly emitted, and another part may be reflected back to the semiconductor epitaxial stack and finally emitted from the light - emitting surface after being reflected again. Thereby, the light - emitting efficiency of the light - emitting diode is improved, and its brightness is increased.

[0028] Optionally, the projection of the insulating reflection layer and the projection of the first electrode have the same projection contour.

[0029] The insulating reflective layer having the same profile as the first electrode can ensure that the insulating reflective layer is disposed around the first electrode, increasing the reflection of light around the electrode, which is beneficial to improving the light extraction efficiency.

[0030] Optionally, the height of the insulating reflective layer is less than or equal to the height of the first electrode.

[0031] Optionally, the spacing distance between the insulating reflective layer and the first electrode is between 1 μm and 10 μm.

[0032] Optionally, the width of the insulating reflective layer is between 1 μm and 5 μm.

[0033] The height of the insulating reflective layer being less than or equal to the height of the first electrode and having the above-mentioned spacing distance from the first electrode can ensure that subsequent operations such as wire bonding at the first electrode are not affected while reflecting the incident light, thereby improving the reliability of the light-emitting diode.

[0034] Optionally, the height of the insulating reflective layer is between 1 μm and 5 μm.

[0035] The setting of the width of the insulating reflective layer can minimize its area ratio on the light extraction surface, which is beneficial to ensuring that the light-emitting diode has sufficient light extraction area and improving its light extraction efficiency.

[0036] Optionally, the longitudinal cross-section of the insulating reflective layer is triangular, trapezoidal or rectangular.

[0037] The longitudinal cross-section of the insulating reflective layer can be of various shape structures, so its design diversity and applicability can be increased, and the structure of the insulating reflective layer can be adjusted according to the specific structure and design requirements of the light-emitting diode chip.

[0038] Optionally, the insulating reflective layer is a single-layer or multi-layer transparent material layer.

[0039] Optionally, the material of the insulating reflective layer is any one or more of SiO2, Si3N4, Al2O3, TiO2, ZnO, HfO2. The above materials are materials with high reflectivity and high transparency. Thus, the material selection of the insulating reflective layer can be increased, and the material can be selected according to the actual design needs of the light-emitting diode.

[0040] Optionally, the first semiconductor layer is a semiconductor layer containing N-type impurities.

[0041] Optionally, the light-emitting diode further includes:

[0042] A dielectric layer formed on the side of the second semiconductor layer away from the active layer, and through holes are formed in the dielectric layer;

[0043] A metal reflective layer is formed on a side of the dielectric layer away from the second semiconductor layer and fills the through hole;

[0044] A bonding layer is formed on a side of the metal reflective layer away from the dielectric layer;

[0045] A substrate is formed on a side of the bonding layer away from the metal reflective layer.

[0046] Optionally, when projected onto a plane where the light-emitting surface is located, the through holes are distributed in an area outside a projection range of the insulating reflective layer.

[0047] As described above, the light-emitting diode of the present application is preferably a vertical structure. The dielectric layer and the metal reflective layer can form a total reflection structure to reflect light radiated by the active layer to the light-emitting surface side, and cooperate with the insulating reflective layer on the light-emitting surface side to increase the light-emitting efficiency and brightness of the light-emitting diode.

[0048] Another embodiment of the present invention provides a light-emitting device, which includes the light-emitting diode provided by the present application. Since the light-emitting device includes the light-emitting diode of the present application, good light-emitting efficiency and brightness can be achieved.

[0049] Embodiment 1

[0050] This embodiment provides a light-emitting diode. As Figure 2 and Figure 3 shown, the light-emitting diode 100 at least includes a semiconductor epitaxial stack 110, which includes a first semiconductor layer 111, an active layer 112, and a second semiconductor layer 113 stacked in sequence. The semiconductor epitaxial stack 110 can be any semiconductor epitaxial stack 110 that can emit light under the action of voltage. In this embodiment, the semiconductor epitaxial stack 110 is preferably an AlGaInP-based epitaxial structure. The first semiconductor layer 111 can be an N-type layer. Correspondingly, the second semiconductor layer 113 is a P-type layer, and vice versa is also feasible. In this embodiment, an example is given where the first semiconductor layer 111 is an N-type layer and the second semiconductor layer 113 is a P-type layer.

[0051] In an alternative embodiment, the first semiconductor layer 111 is an N-type AlInP layer for providing electrons. The N-type AlInP layer provides electrons by doping with an n-type impurity. The n-type impurity can be, for example, Si, Ge, Sn, Se, and Te, etc. In this embodiment, the n-type impurity is preferably Si, and the Si doping concentration is in 1×10 18 Atoms / cm3~2×10 18Between atoms / cm3 to provide electrons for radiative recombination. The second semiconductor layer 113 is a P-type AlInP layer, and holes are provided by doping with P-type impurities, which can be Mg, Zn, Ca, Sr, C, Ba, etc. In this embodiment, the P-type impurity is preferably Mg or C. The active layer 112 is a multiple quantum well layer, for example, a multiple quantum well layer formed by AlGaInP / AlInP. Among them, the number of periods of the active layer 112 is 2 to 100, the thickness of the well layer is 2 nm to 25 nm, the thickness of the barrier layer is 2 nm to 25 nm, and the thicknesses of the well layer and the barrier layer can be the same or different, which can be set according to actual needs. The active layer 112 emits light with a wavelength of 550 nm to 950 nm.

[0052] As Figure 2 shown, in this embodiment, the side of the first semiconductor layer 111 away from the active layer 112 is formed as the light-emitting surface of the light-emitting diode 100. A first electrode 151 in the electrode structure of the light-emitting diode 100, and an insulating reflective layer 160 spaced from the first electrode 151 are formed on this light-emitting surface. Optionally, there may be an N-type ohmic contact layer 153 between the first electrode 151 and the first semiconductor layer 111. The insulating reflective layer 160 is spaced from the first electrode 151 and is disposed around the first electrode 151. That is, the insulating reflective layer 160 has the same contour as the first electrode 151 and forms a closed figure around the first electrode 151. In an alternative embodiment, the shape of the longitudinal cross-section of the above-mentioned insulating reflective layer 160 can be any suitable shape, such as a rectangle, a triangle, a trapezoid, etc., which is easy to operate and can make the insulating reflective layer 160 have a good reflection effect.

[0053] Specifically, as Figure 2 shown, the above-mentioned first electrode 151 has a pad area 1511 and an extension bar 1512. The extension bar 1512 extends from the pad area 1511 to other areas of the light-emitting surface to improve the current diffusion effect and uniformity on the side of the first semiconductor layer 111. In an alternative embodiment, the above-mentioned extension bar 1512 is formed as a finger-shaped extension bar 1512, and the first electrode 151 may include one or more of the above-mentioned extension bars 1512. Projected on the plane of the light-emitting surface, that is, in the Figure 2 top view direction, the projection of the first electrode 151 completely falls within the projection range of the insulating reflective layer 160. As Figure 2 shown, the insulating reflective layer 160 forms a closed figure along the contours of the pad area 1511 and the extension bar 1512 of the first electrode 151, so that the pad area 1511 and the extension bar 1512 of the first electrode 151 are both surrounded by the insulating reflective layer 160.

[0054] Optionally, as Figure 2As shown, the width of the insulating reflective layer 160 satisfies: 1 μm ≤ W ≤ 5 μm. For example, W = 2 μm; W = 3 μm; W = 5 μm, etc. The width of the insulating reflective layer 160 is defined such that it does not cover too much of the light-emitting surface, avoiding light-emitting surface loss caused by excessive coverage and affecting the light-emitting efficiency. Combining Figure 3 and Figure 4 , the height of the insulating reflective layer 160 protruding on the light-emitting surface is not higher than the height of the first electrode 151, that is, the height H2 of the insulating reflective layer 160 is less than or equal to the height H1 of the first electrode 151. Further, the height H1 of the above-mentioned first electrode 151 satisfies: 2 μm ≤ H1 ≤ 5 μm, and the height H2 of the insulating reflective layer 160 satisfies: 1 μm ≤ H2 ≤ 5 μm. In addition, the spacing distance D between the first electrode 151 and the insulating reflective layer 160 satisfies: 1 μm ≤ D ≤ 10 μm. For example, D = 2 μm; D = 5 μm; D = 7 μm; D = 10 μm, etc. The definition of the height of the insulating reflective layer 160 and the first electrode 151 and the spacing distance therebetween can ensure that the insulating reflective layer 160 has a good reflection effect on the incident light, and at the same time ensure that the insulating reflective layer 160 will not affect the subsequent wire bonding and other processes of the first electrode 151, especially the pad area 1511, and ensure the reliability of the light-emitting diode 100.

[0055] Optionally, the above-mentioned insulating reflective layer 160 can be a single-layer structure or a multi-layer structure. Further, the insulating reflective layer 160 is a transparent material layer. For example, it can be any one or a combination of materials with high reflectivity and high transparency such as SiO2, Si3N4, Al2O3, TiO2, ZnO, HfO2, etc. Further, the above-mentioned insulating reflective layer 160 can be formed into a DBR structure with a total reflection effect, such as a DBR structure formed by SiO2 and TiO2. The material selection of the insulating reflective layer 160 can be carried out according to the actual design requirements of the light-emitting diode 100, increasing its scope of application.

[0056] Referring again to Figure 3, the light-emitting diode 100 of this embodiment further includes a substrate 140, and the semiconductor epitaxial stack 110 is bonded to the substrate 140 from one side of the second semiconductor layer 113. A bonding layer 180 is formed between the semiconductor epitaxial stack 110 and the substrate 140, and the bonding layer 180 bonds the semiconductor epitaxial stack 110 and the substrate 140 together. The above-mentioned substrate 140 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. Optionally, the bonding layer 180 is a metal bonding layer, such as Cu, Al, Sn, Au, Ag, Pb, Ti, Ni, In, Pt, or W, etc. A dielectric layer 120 and a metal reflection layer 130 are further formed between the bonding layer 180 and the semiconductor epitaxial stack 110, and the metal reflection layer 130 is formed between the dielectric layer 120 and the bonding layer 180. Specifically, the dielectric layer 120 is formed on the side of the second semiconductor layer 113 away from the active layer 112, the metal reflection layer 130 is formed on the side of the dielectric layer 120 away from the second semiconductor layer 113, and the bonding layer 180 covers the metal reflection layer 130. In an alternative embodiment, through holes 121 are formed in the dielectric layer 120, and the metal reflection layer 130 fills the through holes 121, thereby realizing electrical connection with the second semiconductor layer 113. Further, the above-mentioned through holes 121 are distributed in a region outside the region corresponding to the closed structure formed by the insulating reflection layer 160. That is, in the projection on the plane where the light-emitting surface is located, the projection of the above-mentioned through holes 121 is located outside the projection range of the insulating reflection layer 160, and within the projection range of the insulating reflection layer 160, it is covered by the above-mentioned dielectric layer 120. Thus, it is possible to prevent the aggregation of current in the region corresponding to the first electrode 151, improve the current uniformity of the light-emitting diode, and further improve its light-emitting efficiency.

[0057] The dielectric layer 120 may be a single-layer structure formed of one of SiO2, SiN, SiON, TiO2, etc., or a multi-layer structure formed by a combination of any several of them. Optionally, it is a DBR structure with a reflection effect, such as a DBR structure formed of SiO2 and TiO2. Optionally, the metal reflective layer may be an alloy of one or more of Ag, Al, Cu, Sn, Au, etc. In this embodiment, the dielectric layer 120 is a DBR structure, and the metal reflective layer 130 is an Ag mirror. The dielectric layer 120 and the metal reflective layer 130 form a total reflection structure, increasing the reflection of the light radiated by the active layer 112 and enhancing the light extraction efficiency of the light-emitting diode 100. In addition, as described above, both the metal reflective layer 130 and the bonding layer 180 are metal layers, so the adhesion between them is good, which is beneficial to improving the reliability of the light-emitting diode. On the other side of the substrate 140 opposite to the semiconductor epitaxial stack 110, a back gold layer is formed, and this back gold layer can be used as the second electrode 152 electrically connected to the second semiconductor layer 113.

[0058] Referring to Figure 3 , in order to further increase the light extraction efficiency of the light-emitting diode 100, in this embodiment, after forming the first electrode 151 and the above-mentioned insulating reflective layer 160, the area outside the area surrounded by the insulating reflective layer 160, that is, the surface of the first semiconductor layer 111 outside the area covered by the first electrode 151 and the insulating reflective layer 160 and the area between the first electrode 151 and the insulating reflective layer 160 is roughened to form a roughened surface, thereby increasing the light extraction rate. At the same time, an insulating protective layer 170 is also formed on the exposed sidewalls of the light-emitting diode 100 to protect the light-emitting diode 100 from damage by external moisture and impurities. Optionally, the insulating protective layer 170 may also extend from the sidewalls to cover the edge area of the light-emitting surface.

[0059] Embodiment 2

[0060] This embodiment provides a light-emitting device. As Figure 5 shown, the light-emitting device 200 includes a circuit board 201 and at least one light-emitting diode 202 fixed to the circuit board 201. The light-emitting diode includes the light-emitting diode provided in the above-mentioned Embodiment 1 of the present application. Since the light-emitting device includes the light-emitting diode provided in Embodiment 1, it has good light extraction efficiency and better reliability at the same time.

[0061] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by 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: A semiconductor epitaxial stack, comprising a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence, wherein a side of the first semiconductor layer away from the active layer is a light emitting surface of the light emitting diode; An electrode structure, comprising a first electrode located on the light emitting surface and electrically connected to the first semiconductor layer; An insulating reflective layer is arranged between the light emitting surface and the first electrode. The insulating reflective layer is arranged around the first electrode to form a closed structure and is projected on the plane where the light emitting surface is located. The projection of the first electrode is located within the projection range of the insulating reflective layer.

2. The light emitting diode according to claim 1, characterized in that: A projection of the insulating reflective layer and a projection of the first electrode have the same projection profile.

3. The light emitting diode according to claim 1 or 2, characterized in that: A height of the insulating reflective layer is less than or equal to a height of the first electrode.

4. The light emitting diode according to claim 1, characterized in that: The spacing distance between the insulating reflective layer and the first electrode is between 1 μm and 10 μm.

5. The light emitting diode according to claim 1, characterized in that: The width of the insulating reflective layer is between 1 μm and 5 μm.

6. The light emitting diode according to claim 1, characterized in that: The height of the insulating reflective layer is between 1 μm and 5 μm.

7. The light emitting diode according to claim 1, characterized in that: The longitudinal cross section of the insulating reflective layer is triangular, trapezoidal or rectangular.

8. The light emitting diode according to claim 7, characterized in that: The insulating reflective layer is a single layer or multiple layers of transparent material.

9. The light emitting diode according to claim 7, characterized in that: The material of the insulating reflective layer is any one or more of SiO2, Si3N4, Al2O3, TiO2, ZnO, and HfO2.

10. The light emitting diode according to claim 7, characterized in that: The first semiconductor layer is a semiconductor layer containing N-type impurities.

11. The light emitting diode according to claim 7, characterized in that: Also includes: a dielectric layer, formed on a side of the second semiconductor layer away from the active layer, wherein a through hole is formed in the dielectric layer; A metal reflective layer, formed on a side of the dielectric layer away from the second semiconductor layer and filling the through hole; A bonding layer is formed on a side of the metal reflective layer away from the dielectric layer; The substrate is formed on a side of the bonding layer away from the metal reflective layer.

12. The light emitting diode according to claim 11, characterized in that: When projected on the plane where the light emitting surface is located, the through holes are distributed in a region outside the projection range of the insulating reflective layer.

13. A light emitting device, characterized in that: The invention comprises a circuit substrate and a light emitting element arranged on the circuit substrate, wherein the light emitting element comprises the light emitting diode according to any one of claims 1 to 12.

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