Light-emitting diode and light-emitting device

Abstract

The present invention relates to the field of semiconductor technology, and more particularly to a light-emitting diode and a light-emitting device. In the light-emitting diode provided by the present invention, a first mesa including an active layer is limited to have a perimeter-to-area ratio γ under equal areas satisfying #imgabs0#. This allows for a smaller exposed side surface of the first mesa under equal active layer light-emitting areas, thereby reducing light absorption and non-radiative recombination problems caused by sidewall defects in low-current light-emitting diodes. Furthermore, a non-planar light-emitting surface can increase the probability of light emitting from the sidewalls of the light-emitting diode, further improving the external luminous efficiency of the light-emitting diode.

Description

Technical Field

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

[0002] In recent years, light-emitting diodes have been widely used and play an increasingly important role in various display systems, lighting systems, automobile taillights and other fields.

[0003] Light emitting diodes (LEDs) have the advantages of low cost, high luminous efficiency, energy saving and environmental protection. They are widely used in lighting, visible light communication, and luminous display scenarios.

[0004] Existing light-emitting diode structures include at least an epitaxial structure, which includes a first-type semiconductor layer, an active layer, and a second-type semiconductor layer stacked in sequence. The first-type semiconductor layer and the second-type semiconductor layer are electrically connected to electrodes. The active layer, also known as the light-emitting layer, is a semiconductor layer that emits light when the LED is in operation. A positive voltage is applied to the positive electrode connection terminal and a negative voltage is applied to the negative electrode connection terminal, thereby applying positive and negative voltages to the ends of the LED die, causing the active layer to emit light. The active layer typically has a quantum well structure.

[0005] For small-sized light-emitting diodes (less than 300μm) operating at low currents (0.01mA to 1.5mA), users have high external quantum efficiency requirements. When light-emitting components operate at low currents, defect absorption and non-radiative recombination caused by exposed sidewall defects become particularly prominent. Summary of the Invention

[0006] In order to reduce the problem of excessive sidewall exposure when the light-emitting diode is operating at a low current as mentioned in the background art, an embodiment of the present invention provides a light-emitting diode having a first surface and a second surface relatively upper and lower, wherein the first surface includes a first side edge, a second side edge, a third side edge, and a fourth side edge connected in sequence, and further includes:

[0007] An epitaxial structure comprising a first mesa and a second mesa stacked sequentially from top to bottom, wherein the first mesa comprises at least a first-type semiconductor layer and an active layer, the second mesa comprises at least a second-type semiconductor layer, and the upper surface area of the second mesa is greater than or equal to the lower surface area of the first mesa;

[0008] The area of the projection of the first platform on the plane where the first surface is located is s, and the ratio of its perimeter to area γ satisfies

[0009] Wherein, L1 is the projection length of the upper surface of the first platform passing through the first side and perpendicular to the plane of the first surface.

[0010] Based on the above technical solution, in a preferred embodiment, the thickness of the first type semiconductor layer is 2-5 μm, the thickness of the active layer is 0.02-0.07 μm, and the thickness of the second type semiconductor layer is 3-11 μm.

[0011] Based on the above technical solution, in a preferred embodiment, the ratio of the projected area of the first platform on the plane where the first surface is located to the projected area of the second platform on the plane where the first surface (100) is located is 0.02 to 0.6.

[0012] Based on the above technical solution, in a preferred embodiment, when viewed perpendicular to the first surface, the length of the portion of the side edge of the upper surface outer contour of the first platform parallel to the first side edge of the first surface of the light-emitting diode is L2, L1 is greater than L2, and at least one side of the projection of the first platform onto the plane on which the first surface lies is an arc.

[0013] Based on the above technical solution, in a preferred embodiment, the projection shape of the first platform on the plane where the first surface is located is a circle or an ellipse or a combination of an arc and a straight line.

[0014] Based on the above technical solution, in a preferred embodiment, the projection shape of the second platform on the plane where the first surface of the light emitting diode is located is circular, elliptical, or rectangular with rounded corners.

[0015] Based on the above technical solution, in a preferred embodiment, the first side is equal to the third side, the second side is equal to the fourth side, and the length of the first side is greater than the length of the second side;

[0016] The position of the outer contour of the upper surface of the second platform 10b closest to the first side or the third side of the first surface 100 has a minimum distance D1 to the side of the upper surface of the first platform 10b;

[0017] The position of the outer contour of the upper surface of the second platform 10b closest to the second side or the fourth side of the first surface 100 has a minimum distance D2 from the side of the upper surface of the first platform 10b;

[0018] The D1 is smaller than D2.

[0019] Based on the above technical solution, in a preferred embodiment, the minimum distance D1 between the side of the plane projection pattern of the first surface of the light-emitting diode and the first side or the third side of the first platform is 2-6 μm.

[0020] Based on the above technical solution, in a preferred embodiment, a first contact electrode is provided on the first type semiconductor layer, and the first contact electrode includes a first point electrode and two first extension portions b, and the two first extension portions extend from the first point electrode toward different side directions of the light-emitting diode.

[0021] Based on the above technical solution, in a preferred embodiment, the two first extension portions form a straight line segment or an arc segment.

[0022] Based on the above technical solution, in a preferred embodiment, when the two first extensions form an arc segment, both ends of the arc segment projected on the first surface are located on the center line of the projection shape of the first platform on the first surface.

[0023] Based on the above technical solution, in a preferred embodiment, a second contact electrode is provided on the second type semiconductor layer, and the second contact electrode is a point electrode, or the second contact electrode includes a second point electrode and two second extensions, and the two second extensions extend from the second point electrode respectively toward opposite sides of the light-emitting diode.

[0024] Based on the above technical solution, in a preferred embodiment, in a plane perpendicular to the first surface of the light-emitting diode and passing through the fourth side, the projection length of the second contact electrode on the plane is smaller than the projection length of the first contact electrode on the plane.

[0025] Based on the above technical solution, in a preferred embodiment, it further includes an insulating protection layer, wherein the insulating protection layer is provided on the first surface and sidewalls of the epitaxial structure; a first pad electrode and a second pad electrode are provided above the insulating protection layer;

[0026] The insulating protection layer is provided with a first opening and a second opening. The first pad electrode is filled in the first opening to be electrically connected to the first type semiconductor layer; the second pad electrode is filled in the second opening to be electrically connected to the second type semiconductor layer.

[0027] Based on the above technical solution, in a preferred embodiment, a first contact electrode is provided between the first pad electrode and the first type semiconductor layer; and a second contact electrode is provided between the second pad electrode and the second type semiconductor layer.

[0028] Based on the above technical solution, in a preferred embodiment, the bottom width of the first opening is less than or equal to the bottom width of the first contact electrode, and the bottom width of the second opening is less than or equal to the bottom width of the second contact electrode.

[0029] Based on the above technical solution, in a preferred embodiment, viewed perpendicular to the first surface direction, the first pad electrode and the second pad electrode respectively include partial areas overlapping with the area of the active layer, or the first pad electrode and the second pad electrode are completely located in an area outside the active layer.

[0030] Based on the above technical solution, in a preferred embodiment, it further includes a substrate, wherein a bonding layer is provided between the substrate and the epitaxial structure;

[0031] The bonding layer is a single layer or composite layer structure, and is made of conductive material or insulating material.

[0032] Based on the above technical solution, in a preferred embodiment, the thickness of the bonding layer is 1 to 5 μm.

[0033] Based on the above technical solution, in a preferred embodiment, the size of the light emitting diode is less than 300 μm.

[0034] The present invention also provides an embodiment of a light emitting diode, comprising a first surface and a second surface facing each other, wherein the first surface comprises a first side, a second side, a third side, and a fourth side connected in sequence, and further comprising:

[0035] An epitaxial structure comprising a first mesa and a second mesa stacked sequentially from top to bottom, wherein the first mesa comprises at least a first-type semiconductor layer and an active layer, the second mesa comprises at least a second-type semiconductor layer, and the upper surface area of the second mesa is greater than or equal to the lower surface area of the first mesa;

[0036] The size of the light emitting diode is less than 300 μm. The projection of the first platform on the plane where the first surface is located has at least one side that is arc-shaped. The protrusion of the arc is closer to the side of the arc toward the first surface of the light emitting diode.

[0037] In another embodiment of the present invention, a light-emitting device is provided, which uses any of the light-emitting diodes described above.

[0038] In the inventive concept provided by the technical solution of the present invention, the first platform including the active layer satisfies the ratio γ of the perimeter to the area under the same area by limiting the perimeter to the area under the same area. With the same active layer light-emitting area, the side of the first platform is less exposed, thereby reducing the problems of light absorption and non-radiative recombination caused by side wall defects in low-current light-emitting diodes. In addition, the non-planar light-emitting surface can increase the probability of light emitting from the side wall of the light-emitting diode, further improving the external light-emitting efficiency of the light-emitting diode.

[0039] In another embodiment of the present invention, for a light-emitting diode (LED) smaller than 300 μm, at least one side of the projection of the first mesa onto the plane where the first surface lies is curved. This allows for a smaller portion of the side surface of the first mesa to be exposed, given the same light-emitting area above and below the active layer. This reduces light absorption and non-radiative recombination problems caused by sidewall defects in low-current LEDs. Furthermore, a circular, elliptical, or rounded light-emitting surface can increase the probability of light emitting from the sidewalls of the LED, further improving the external luminous efficiency of the LED.

[0040] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to 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 paying any creative labor.

[0042] Figure 1 It is a schematic cross-sectional view of the light emitting diode structure in the existing technical solution;

[0043] Figure 2 This is a schematic top view of the light emitting diode structure in the existing technical solution;

[0044] Figure 3 A schematic diagram of an existing technical solution in which both the first platform and the second platform are rectangular parallelepiped structures;

[0045] Figure 4 A schematic cross-sectional view of a light emitting diode structure according to an embodiment of the present invention

[0046] Figure 5 Schematic diagram of a first embodiment of the projection shape of the first platform onto the plane where the first surface is located in an embodiment of the present invention;

[0047] Figure 62. A schematic diagram of a second embodiment of the projection shape of the first platform onto the plane where the first surface is located in an embodiment of the present invention;

[0048] Figure 7 Schematic diagram of a third embodiment of the projection shape of the first platform onto the plane where the first surface is located in an embodiment of the present invention;

[0049] Figure 8 Schematic diagram of a fourth embodiment of the projection shape of the first platform onto the plane where the first surface is located in an embodiment of the present invention;

[0050] Figure 9 Schematic diagram of the optical path of light inside a light-emitting diode;

[0051] Figures 10-12 Schematic diagrams showing that the projection shapes of the second platform 10b on the plane where the first surface of the light-emitting diode is located are respectively circular, elliptical, and rectangular with rounded corners;

[0052] Figure 13 A schematic diagram of an embodiment of a first extension portion and a second extension portion of a light emitting diode;

[0053] Figure 14 A schematic diagram of another embodiment of the first extension portion and the second extension portion of the light emitting diode;

[0054] Figure 15 A schematic top view of a light emitting diode structure according to an embodiment of the present invention;

[0055] Figure 16 for Figure 15 Schematic cross-section of section line BB';

[0056] Figure 17 A schematic top view of a light emitting diode structure in another embodiment of the present invention;

[0057] Figure 18 for Figure 15 Schematic cross-section of section line C-C';

[0058] Figure 19 A schematic diagram of optical test results according to an embodiment is also provided.

[0059] Reference numerals:

[0060] 10a first platform 10b second platform 11 first type semiconductor layer

[0061] 12 Second type semiconductor layer 13 Active layer 100 First surface

[0062] 200 Second surface 31 First contact electrode 31a First point electrode

[0063] 31b first extension portion 32 second contact electrode 32a second dot electrode

[0064] 32b second extension 40 insulating protection layer 51 first pad electrode

[0065] 52 Second pad electrode 20 Bonding layer 70 Electrical insulation layer

[0066] 40a first opening 40b second opening DETAILED DESCRIPTION

[0067] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0068] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" and the like to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0069] In addition, the terms "first," "second," and similar words do not denote any order, quantity, or importance, but are used to distinguish one component from another. "Connected" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, optical connections, etc., whether direct or indirect.

[0070] It should be understood that the terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. It should be further understood that when the terms "comprise" and "include" are used in the present invention, they are used to indicate the presence of stated features, integers, steps, elements, and / or components, and do not exclude the presence or addition of one or more other features, integers, steps, elements, and / or combinations thereof.

[0071] Unless otherwise defined, all terms (including technical and scientific terms) used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. It should be further understood that the terms used in the present invention should be understood to have the same meaning as these terms in the context of this specification and the relevant field, and should not be understood in an idealized or overly formal sense, unless explicitly defined as such in the present invention.

[0072] The existing flip-chip light-emitting diodes with a size less than 300μm, that is, the side length of the flip-chip light-emitting diode is less than 300μm, are small-sized light-emitting diodes, usually with an operating current of 0.01mA to 1.5mA. Figure 1 As shown, it includes: an epitaxial structure, having a first platform 10a and a second platform 10b stacked in sequence from top to bottom, the first platform 10a includes at least a first type semiconductor layer 11 and an active layer 13, the second platform 10b includes at least a second type semiconductor layer 12, and the upper surface area of the second platform 10b is greater than or equal to the lower surface area of the first platform 10a; wherein, as Figure 2 and 3 As shown, the first platform 10a and the second platform 10b are both designed as rectangular parallelepiped structures.

[0073] When the above-mentioned small-sized light-emitting diode is working, since a large proportion of the active layer area is exposed on the sidewall, the light absorption and non-radiative recombination problems caused by the sidewall defects become particularly prominent.

[0074] In order to mainly solve the above technical problems, according to the related concepts of the technical solution of the present invention, the following embodiments are provided:

[0075] Provide a light emitting diode, such as Figure 4 and Figure 5 As shown, it has a first surface 100 and a second surface 200 that are relatively upper and lower. The first surface 100 includes a first side a, a second side b, a second side c, and a fourth side d that are sequentially connected. The four sides can sequentially form a rectangle or a square. The specific shape depends on the actual product. It also includes:

[0076] An epitaxial structure comprising a first platform 10a and a second platform 10b stacked sequentially from top to bottom, wherein the first platform 10a comprises at least a first-type semiconductor layer 11 and an active layer 13, and the second platform 10b comprises at least a second-type semiconductor layer 12, and the upper surface area of the second platform 10b is greater than or equal to the lower surface area of the first platform 10a;

[0077] In the above embodiment, specifically, the epitaxial structure is grown on an original substrate using methods such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE); the original growth substrate can include at least one of sapphire (Al2O3), SiC, GaAs, GaN, ZnO, GaP, InP and Ge, and is not limited to the examples listed here. In this embodiment, GaAs is preferably used as the original growth substrate.

[0078] The first-type semiconductor layer 11 and the second-type semiconductor layer 12 are semiconductors with different conductivity types, electrical properties, and polarities, and they provide electrons or holes depending on the doped elements. For example, when the first-type semiconductor layer 11 is n-type and the second-type semiconductor layer 12 is p-type, the active layer 13 is formed between the first-type semiconductor layer 11 and the second-type semiconductor layer 12. Electrons and holes recombine within the active layer 13 under the influence of a current and convert electrical energy into light energy to emit light. By changing the physical and chemical composition of one or more layers of the epitaxial light-emitting layer, the wavelength of the light emitted by the light-emitting diode can be adjusted. Conversely, in this embodiment, it is preferred that the first-type semiconductor layer 11 is n-type and the second-type semiconductor layer 12 is a p-type light-emitting diode.

[0079] The active layer 13, also known as the light-emitting layer or active layer, is located between the first-type semiconductor layer 11 and the second-type semiconductor layer 12 and is capable of converting electrical energy into light energy. The radiation emitted by the active layer 13 can be red light or infrared light radiation;

[0080] Common materials for the active layer 13 are aluminum gallium indiphosphide (AlGaInP) series, aluminum gallium indium nitride (AlGaInN) series, and zinc oxide (ZnO) series. The active layer 13 can be a single heterostructure (SH), a double heterostructure (DH), a double-sided double heterostructure (DDH), or a multi-quantum well (MQW) structure. When the active layer 13 is based on materials from the aluminum gallium indium phosphide (AlGaInP) series, the active layer 13 emits red, orange, or yellow amber light through doping of the semiconductor layer; when based on materials from the aluminum gallium indium nitride (AlGaInN) series, the active layer 13 emits blue or green light. In this embodiment, a light-emitting diode that emits red or infrared radiation is preferably used as an example.

[0081] In some embodiments, preferably, reference Figure 4 , the light-emitting diode also includes a substrate 50. In the embodiment of the preparation process of the light-emitting diode, an epitaxial structure grown on the original substrate is first provided, and then the epitaxial structure of the light-emitting diode element is bonded and transferred to the substrate 10, and then the original epitaxial growth substrate of the epitaxial structure of the light-emitting diode element is removed, and the bonding between the substrate 10 and the epitaxial structure is completed. The substrate 10 can be a conductive substrate or a non-conductive substrate, and can also be transparent or non-transparent. A bonding layer 20 is provided between the substrate 50 and the epitaxial structure; preferably, the bonding layer 20 is a single layer or a composite layer structure, and is made of a conductive material or an insulating material. In one embodiment, with reference to Figure 4 The substrate 50 and the epitaxial structure are bonded via a bonding layer 20. The bonding layer 20 is a single layer or composite layer structure, preferably 1 to 5 μm thick, and is made of a conductive or insulating material. The bonding layer 20 can be transparent or non-transparent. When the bonding layer 20 is a composite layer structure, it comprises a conductive bonding layer and a non-conductive bonding layer; the non-conductive bonding layer is closer to the substrate than the conductive bonding layer. Furthermore, the conductive bonding layer is an oxide containing at least one selected from the group consisting of Zn, In, Sn, and Mg. More preferably, the conductive bonding layer is ZnO, In2O3, SnO2, ITO (IndiumTinOxide), IZO (IndiumZincOxide), GZO (GalliumdopedZincOxide), or any combination thereof. The material of the non-conductive bonding layer is preferably Al2O3, SiO2, SiNx, MgF2, or TiO2. It should be noted that the substrate 50 is not necessary. In some embodiments, the substrate 50 can also be removed, such as in the case of a micro LED chip.

[0082] like Figure 5-8 As shown, the area of the projection of the first platform 10a on the plane where the first surface 100 is located is s, and the ratio of its perimeter to area γ satisfies

[0083] Wherein, L1 is the projection length of the upper surface of the first platform 10 a in a direction passing through the first side and perpendicular to the plane of the first surface 100 .

[0084] In this embodiment, the range of the perimeter area ratio γ of the projection of the first platform 10a onto the plane where the first surface 100 is located is limited to:

[0085] When the When the first platform 10a is a platform with a circular cross section, refer to Figure 5, the projection of the first platform 10a on the plane where the first surface 100 is located is a circle; in this case, under the same light-emitting area (that is, when the upper and lower surface areas of the first platform 10a are constant), the circumference of the upper and lower surfaces of the first platform 10a is minimized, and when the thickness of the first platform 10a is constant, the side area of the first platform 10a can be minimized, and the exposed area of the sidewall is also smaller, thereby reducing the problems of light absorption and non-radiative recombination caused by sidewall defects in low-current light-emitting diodes.

[0086] At the same time, the definition (when When, that is, in the prior art solution, the first platform 10a adopts a rectangular parallelepiped structure, in a specific design embodiment, the projection shape of the first platform 10a onto the plane where the first surface 100 is located can be a combination of an arc and a straight line, such as a combination of an arc and a straight line (refer to Figure 6 or Figure 8 ), or oval (ref. Figure 7 ). These embodiments all satisfy the perimeter-area ratio γ satisfies This solution overcomes the limitations of the rectangular design of the first platform 10a in existing small-size LEDs. Thus, while maintaining the same light-emitting area (i.e., the upper and lower surfaces of the first platform 10a are fixed), and the thickness of the first platform 10a is constant, the side surface area of the first platform 10a can be reduced compared to the rectangular design of the first platform 10a in the prior art. Consequently, the exposed sidewall area is also reduced, thereby reducing the problems of light absorption and non-radiative recombination caused by sidewall defects in low-current LEDs.

[0087] In addition, in the prior art, since the first platform 10a adopts a rectangular parallelepiped design, such as Figure 3 As shown, the incident angle θ1 of the light emitted by the active layer 13 on the surface of the first platform 10a is larger. Due to the influence of the refractive index of the material, a large part of the light will be reflected back into the semiconductor again due to total internal reflection. After multiple reflections, most of it will be absorbed by the semiconductor structure itself, resulting in extremely low light extraction efficiency of the structure. Figure 9 As shown in the optical path principle diagram, the incident angle θ2 of the light emitted from the non-planar surface is significantly smaller than θ1, so the light can more likely avoid total reflection on the surface of the first platform 10a, thereby increasing the probability of light emitting from the side wall of the light-emitting diode and further improving the external luminous efficiency of the light-emitting diode.

[0088] refer to Figure 5-8Based on the above technical solution, in a preferred embodiment, when viewed perpendicular to the first surface, the length of the portion of the side edge of the upper surface outer contour of the first platform 10a parallel to the first side edge a of the first surface of the light-emitting diode is L2, L1 is greater than L2, and at least one side of the projection of the first platform 10a onto the plane where the first surface lies is an arc. Embodiments in which L1 is greater than L2 also include the following: Figure 6 、 Figure 7 、 Figure 8 As shown, in which Figure 5 、 Figure 7 In the embodiment of FIG, the length of L2 is 0. In the technical solution of this embodiment, when L1 is greater than L2, the projection of the side surface of the first terrace 10a on the plane where the first surface 100 of the LED is located is non-linear. Consequently, for the same area, the side surface of the first terrace 10a can have a smaller area compared to the prior art solution in which the first terrace 10a has a rectangular parallelepiped structure. That is, for the same upper and lower light-emitting areas of the active layer, the side surface of the first terrace 10a is less exposed, thereby reducing the problems of light absorption and non-radiative recombination caused by sidewall defects in low-current LEDs.

[0089] In some embodiments, preferably, reference Figure 10 、 11 As shown in FIG. 12 , the projection of the second platform 10b onto the plane of the first surface 100 of the LED is in the shape of a circle, an ellipse, or a rectangle with rounded corners. These second platform 10b designs can be combined with the design of the first platform 10a described above in any combination. Similarly, by adopting the above-described design for the second platform 10b, the probability of the light emitted by the active layer 13 being consumed by total internal reflection within the LED can be further reduced, thereby improving the external luminous efficiency of the LED.

[0090] Based on the above embodiment, preferably, the thickness of the first-type semiconductor layer 11 is 2-5 μm, the thickness of the active layer 13 is 0.02-0.07 μm, and the thickness of the second-type semiconductor layer 12 is 6-11 μm. In this embodiment, by controlling the epitaxial growth process, the thickness of the epitaxial structure is further reduced, thereby reducing the thickness of the first mesa 10a. This not only reduces the area of defects exposed on the sidewalls, but also reduces the number of defects between epitaxial film layers, thereby reducing the problems of light absorption and non-radiative recombination caused by defects in low-current light-emitting diodes.

[0091] In some embodiments, preferably, the ratio of the projected area of the first platform 10a on the plane of the first surface 100 to the projected area of the second platform 10b on the plane of the first surface 100 is 0.02 to 0.6. This design allows the chip to maintain a stable external quantum efficiency by keeping the current density injected into the active layer within an appropriate operating range when driven by a low current (0.01 mA to 1 mA), while avoiding a significant decrease in external quantum efficiency due to excessively low current density.

[0092] In some embodiments, preferably, reference Figure 5-8 As shown, taking the first side a, the second side b, the second side c, and the fourth side d as an example, the first side a and the third side c are equal, the second side b and the fourth side c are equal, and the length of the first side a is greater than the length of the second side b; the first side and the third side are equal, the second side and the fourth side are equal, and the length of the first side is greater than the length of the second side; the position of the outer contour of the upper surface of the second platform 10b that is closest to the first side or the third side of the first surface 100, and the minimum distance to the side edge of the upper surface of the first platform 10b is D1; the position of the outer contour of the upper surface of the second platform 10b that is closest to the second side or the fourth side of the first surface 100, and the minimum distance to the side edge of the upper surface of the first platform 10b is D2; and D1 is smaller than D2.

[0093] Furthermore, a minimum distance D1 between the side of the first platform 10a on the plane projection pattern of the first surface 100 of the light emitting diode and the first side or the third side is 2-6 μm.

[0094] In some embodiments, in the above technical solutions or combined solutions, small-sized flip-chip light-emitting diodes with a size range of less than 300 μm are preferably considered.

[0095] In the above-mentioned options and their combination technologies, this embodiment also provides a preferred solution: Figure 5-Figure 8 As shown, a first contact electrode 31 is provided on the first-type semiconductor layer 11. The first contact electrode 31 includes a first dot-shaped electrode 31a and two first extensions 31b. The two first extensions 31b extend from the first dot-shaped electrode 31a toward different sides of the light-emitting diode. This design allows for more uniform current diffusion in the light-emitting area, thereby improving light uniformity.

[0096] In some embodiments, the two first extensions 31b may form a straight line (see Figure 13 ) segment or form an arc segment (reference Figure 5 、 Figure 14 );

[0097] When the two first extensions 31b form an arc segment, preferably, as Figure 14 As shown, the two ends of the arc segment projected on the first surface 100 are located on the centerline of the projection of the first platform 10a on the first surface 100. Further in conjunction with the embodiment of the present invention, in which the upper surface of the first platform 10a is circular, the arc segments formed by the two first extensions 31b can better match the shape of the first platform 10a, reducing the uneven current diffusion in the corners of the light-emitting area, thereby further improving the uniformity of current diffusion in the light-emitting area. The two ends of the arc segment projected on the first surface 100 are located on the centerline of the projection of the first platform 10a on the first surface 100, which can further facilitate the diffusion of current between different electrodes of the light-emitting diode.

[0098] In some preferred embodiments, a second contact electrode 32 is provided on the second type semiconductor layer 12, and the second contact electrode 32 can be combined with the first contact electrode 31, as shown in FIG. Figure 5 、 14 As shown, the second contact electrode 32 is a point-shaped electrode, and this solution is preferably combined with the solution in which the two first extension portions 31b form an arc segment;

[0099] or as Figure 13 As shown, the second contact electrode 32 includes a second dot electrode 32a and two second extensions 32b, and the two second extensions 32b extend from the second dot electrode 32a to opposite sides of the light emitting diode. Figure 13 As shown, in a plane perpendicular to the first surface 100 of the light-emitting diode and passing through the fourth side, the projection length of the second contact electrode 32 on the plane is smaller than the projection length of the first contact electrode 31 on the plane. Through this solution, the luminous efficiency and ESD resistance of the flip-chip light-emitting element can be effectively improved.

[0100] In this embodiment, when the first type semiconductor layer 11 is n-type, the second type semiconductor layer 12 is a p-type light emitting diode.

[0101] In some embodiments, preferably, Figure 4As shown, the epitaxial structure of the light-emitting diode comprises a first platform 10a and a second platform 10b stacked sequentially from top to bottom. The first platform 10a includes at least a first-type semiconductor layer 11 and an active layer 13, and the second platform 10b includes at least a second-type semiconductor layer 12. The upper surface area of the second platform 10b is greater than or equal to the lower surface area of the first platform 10a. The epitaxial structure also includes an insulating protective layer 40, which is disposed on the upper surface and sidewalls of the epitaxial structure. A first pad electrode 51 and a second pad electrode 52 are disposed above the insulating protective layer 40.

[0102] The insulating protection layer 40 is provided with a first opening 40a and a second opening 40b;

[0103] In this embodiment, the specific material of the insulating protective layer 40 can be a non-conductive material selected from inorganic oxides or nitrides, or silicon dioxide, silicon nitride, titanium oxide, tantalum oxide, niobium oxide, barium titanate, magnesium fluoride aluminum oxide, or a combination thereof, the combination of which can be, for example, a Bragg reflector (DBR) formed by repeatedly stacking two materials.

[0104] Preferably, reference Figure 4 and Figure 5 , Figure 4 for Figure 5 In the cross-sectional diagram along the section line AA, a first contact electrode 31 is provided between the first pad electrode 51 and the first type semiconductor layer 11 ; and a second contact electrode 32 is provided between the second pad electrode 52 and the second type semiconductor layer 12 .

[0105] Viewed from a direction perpendicular to the first surface 100, the first opening 40a exposes a portion of the first type semiconductor layer 11, and the first pad electrode 51 is filled in the first opening 40a to directly contact the first type semiconductor layer 11 for electrical connection or to make an ohmic connection with the first type semiconductor layer 11 through the first contact electrode 31, and covers the first opening 40a; the second opening 40b exposes a portion of the second type semiconductor layer 12, and the second pad electrode 52 is filled in the second opening 40b to directly contact the second type semiconductor layer 12 for electrical connection or to make an ohmic connection with the second type semiconductor layer 12 through the second contact electrode 32; the first pad electrode 51 and the second pad electrode 52 partially cover the insulating protection layer 40, and each includes a partial area overlapping with the area of the active layer 13.

[0106] Alternatively, in another embodiment, reference Figure 15 and Figure 16 , Figure 16 for Figure 15In the cross-sectional schematic diagram along the section line BB, the first pad electrode 51 and the second pad electrode 52 are completely located in the area outside the active layer 13, wherein the second opening 40b exposes a portion of the second type semiconductor layer 12, the second pad electrode 52 fills the second opening 40b and directly contacts the second type semiconductor layer 12 for electrical connection or ohmically connects to the second type semiconductor layer 12 through the second contact electrode 32, and the second contact electrode 32 is completely located below the second pad electrode 52; the first opening 40a is located above the second type semiconductor layer 12, a portion of the first contact electrode 31 is disposed above the second type semiconductor layer 12, and the other portion is located above the first type semiconductor layer 11 and is electrically connected to the first type semiconductor layer 11; further comprising an electrical insulating layer 70, the electrical insulating layer 70 being interposed between the first contact electrode 31 and the active layer 13 and between the first contact electrode 31 and the second type semiconductor layer 12, so as to prevent the first contact electrode 31 from contacting the active layer 13 and the second type semiconductor layer 12 and causing a short circuit; the first pad electrode 51 fills the first opening 40a and contacts the first contact electrode 31, thereby electrically connecting to the first type semiconductor layer 11 and covering the first opening 40a; at this time, the first pad electrode 51 and the second pad electrode 52 are completely located in an area outside the active layer 13, thereby improving the luminous efficiency of the light-emitting diode;

[0107] For the embodiment in which the first pad electrode 51 and the second pad electrode 52 are completely located outside the active layer 13, the present invention also provides another situation, such as Figure 17 and Figure 18 As shown, Figure 18 for Figure 17In the cross-sectional schematic diagram along the section line BB, viewed from a direction perpendicular to the first surface 100, the first pad electrode 51 and the second pad electrode 52 are completely located in an area outside the epitaxial structure. Specifically, the first opening 40a is located above the bonding layer 20 (if the substrate 60 is not provided with a bonding layer 20, the substrate 60 is used as a reference). A portion of the first contact electrode 31 is provided above the bonding layer 20 and below the first opening 40a, and another portion is located above the first type semiconductor layer 11 and electrically connected to the first type semiconductor layer 11. The first contact electrode 31 is provided with an electrically insulating layer 70, the electrically insulating layer 70 being interposed between the first contact electrode 31 and the active layer 13, between the first contact electrode 31 and the second type semiconductor layer 12, and between the first contact electrode 31 and the bonding layer 20, so as to prevent the first contact electrode 31 from contacting the active layer 13 and the second type semiconductor layer 12 and causing a short circuit. The first pad electrode 51 fills the first opening 40a and contacts the first contact electrode 31, thereby being electrically connected to the first type semiconductor layer 11 and covering the first opening 40a.

[0108] At the same time, the second opening 40b is located above the bonding layer 20 (if the substrate 60 is not provided with a bonding layer 20, the substrate 60 is used as a reference). A portion of the second contact electrode 32 is provided above the bonding layer 20 and below the second opening 40b, and the other portion is located above the second type semiconductor layer 12 and is electrically connected to the second type semiconductor layer 12. The first pad electrode 51 fills the first opening 40a and contacts with the first contact electrode 31, and covers the first opening 40a, thereby being electrically connected to the second type semiconductor layer 12.

[0109] In one embodiment, preferably, in a preferred embodiment, as Figure 16 As shown, the bottom width of the first opening 40 a is less than or equal to the bottom width of the first contact electrode, and the bottom width of the second opening 40 b is less than or equal to the bottom width of the second contact electrode 32 .

[0110] In one embodiment, the projection of the substrate onto the plane where the first surface 100 is located is preferably circular, elliptical, or rectangular with rounded corners. Similarly, the above substrate shape design can further reduce the probability of light emitted by the active layer 13 being consumed by total internal reflection within the LED, thereby improving the external light emitting efficiency of the LED.

[0111] The present invention also provides an embodiment of a light emitting diode, referring to Figure 4The device has a first surface 100 and a second surface 200 that are opposite to each other. The first surface 100 includes a first side, a second side, a third side, and a fourth side that are sequentially connected. The device also includes:

[0112] An epitaxial structure comprising a first platform 10a and a second platform 10b stacked sequentially from top to bottom, wherein the first platform 10a comprises at least a first-type semiconductor layer 11 and an active layer 13, and the second platform 10b comprises at least a second-type semiconductor layer 12, and the upper surface area of the second platform 10b is greater than or equal to the lower surface area of the first platform 10a;

[0113] refer to Figures 5 to 8 In a light-emitting diode having a size less than 300 μm, at least one side of the plane projection of the first platform 10a on the first surface 100 is an arc, and the protruding portion of the arc is closer to the side direction of the arc toward the first surface 100 of the light-emitting diode.

[0114] In the technical solution of this embodiment, by making the first platform 10a have at least one side of the projection of the first platform 10a on the plane where the first surface 100 is located to be an arc, that is, the side of the first platform 10a is an arc surface, or the side surface of the first platform 10a projected on the plane where the first surface 100 of the light-emitting diode is located is non-linear, in a specific design embodiment, the projection shape of the first platform 10a on the plane where the first surface 100 is located can be a combination of an arc and a straight line, such as a combination of an arc and a straight line (refer to Figure 6 and Figure 8 ), or oval (ref. Figure 7 ), through the above-mentioned design limitation, under the same area, the side surface of the first platform 10a can have a smaller area compared with the solution in the prior art where the first platform 10a has a rectangular structure. That is, under the same upper and lower light-emitting areas of the active layer, the side surface of the first platform 10a is exposed less, thereby reducing the problems of light absorption and non-radiative recombination caused by sidewall defects in low-current light-emitting diodes.

[0115] The present invention also provides an embodiment of a light-emitting device, which adopts a light-emitting diode structure as in any of the above embodiments or the preferred schemes in the embodiments and their combinations, and utilizes the red light or infrared light radiation or blue light or green light radiation provided by the light-emitting diode for corresponding display or lighting or use in other optical devices.

[0116] The present invention also provides an optical test of an embodiment, such as Figure 5 As shown, the specifications of the light emitting diode of the test embodiment are 3.5×6mil^ 2The projection of the first platform 10a on the plane where the first surface 100 is located is circular, the two first extensions 31b form arc segments, and the second contact electrode 32 is a point electrode. The product of this embodiment and a chip with the same specifications and a first platform having a rectangular parallelepiped are subjected to optical testing and external quantum efficiency (WPE). Figure 19 As shown, the test results show that when the sample is driven by a small current (0.01mA~1mA), the luminous efficiency of the circular table design chip is greatly improved compared with the luminous efficiency of the chip with the same size and the first table being a rectangular block.

[0117] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above 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 comprising a first surface (100) and a second surface (200) which are relatively upper and lower, wherein the first surface (100) comprises a first side, a second side, a third side, and a fourth side which are connected in sequence, and further comprising: An epitaxial structure comprising a first platform (10a) and a second platform (10b) stacked sequentially from top to bottom, wherein the first platform (10a) comprises at least a first type semiconductor layer (11) and an active layer (13), the second platform (10b) comprises at least a second type semiconductor layer (12), and the upper surface area of the second platform (10b) is greater than or equal to the lower surface area of the first platform (10a); Its characteristics are: The area of the projection of the first platform (10a) on the plane where the first surface (100) is located is s, and the ratio γ of its perimeter to area satisfies ≤γ< ; Wherein, L1 is the projection length of the upper surface of the first platform (10a) in the direction of a plane passing through the first side and perpendicular to the first surface (100); A first contact electrode (31) is provided on the first type semiconductor layer (11), the first contact electrode (31) comprising a first point electrode (31a) and two first extensions (31b), the two first extensions (31b) extending from the first point electrode (31a) towards different side directions of the light emitting diode; A second contact electrode (32) is provided on the second-type semiconductor layer (12); the second contact electrode (32) is a point electrode, or the second contact electrode (32) comprises a second point electrode (32a) and two second extensions (32b); the two second extensions (32b) extend from the second point electrode (32a) toward opposite sides of the light-emitting diode; In a plane perpendicular to the first surface (100) of the light-emitting diode and passing through the fourth side, the projection length of the second contact electrode (32) on the plane is shorter than the projection length of the first contact electrode (31) on the plane; the two first extensions (31b) form an arc segment; The thickness of the first type semiconductor layer (11) is 2-5 μm, the thickness of the active layer (13) is 0.02-0.07 μm, and the thickness of the second type semiconductor layer (12) is 3-11 μm; The light emitting diode has an operating current of 0.01 mA to 1.5 mA and a size of less than 300 μm.

2. The light emitting diode according to claim 1, characterized in that The ratio of the projected area of the first platform (10a) on the plane where the first surface (100) is located to the projected area of the second platform (10b) on the plane where the first surface (100) is located is 0.02-0.

6.

3. The light emitting diode according to claim 1, characterized in that Viewed perpendicularly to the first surface (100), the length of the portion of the side of the outer contour of the upper surface of the first platform (10a) parallel to the first side of the first surface of the light-emitting diode is L2, L1 is greater than L2, and at least one side of the projection of the first platform (10a) onto the plane where the first surface (100) is located is arc-shaped.

4. The light emitting diode according to claim 1, characterized in that The projection shape of the first platform (10a) on the plane where the first surface (100) is located is a circle or an ellipse or a combination of an arc and a straight line.

5. The light emitting diode according to claim 1, characterized in that The projection shape of the second platform (10b) on the plane where the first surface (100) of the light-emitting diode is located is circular, elliptical, or rectangular with rounded corners.

6. The light emitting diode according to claim 1, characterized in that The first side is equal to the third side, the second side is equal to the fourth side, and the length of the first side is greater than the length of the second side; The minimum distance from the position of the first side edge or the third side edge of the outer contour of the upper surface of the second platform (10b) closest to the first surface (100) to the side edge of the upper surface of the first platform (10b) is D1; The minimum distance from the position of the outer contour of the upper surface of the second platform (10b) closest to the second side edge or the fourth side edge of the first surface (100) to the side edge of the upper surface of the first platform (10b) is D2; The D1 is smaller than D2.

7. The light emitting diode according to claim 6, characterized in that The minimum distance D1 between the side of the first platform (10a) on the plane projection graphic of the first surface (100) of the light-emitting diode and the first side or the third side is 2-6 μm.

8. The light emitting diode according to claim 1, characterized in that When the two first extension portions (31b) form an arc segment, the two ends of the arc segment projected on the first surface (100) are located on the center line of the projection shape of the first platform (10a) on the first surface (100).

9. The light emitting diode according to claim 1, characterized in that It also includes an insulating protective layer (40), the insulating protective layer (40) being arranged on the first surface (100) and the sidewall of the epitaxial structure; a first pad electrode (51) and a second pad electrode (52) are arranged above the insulating protective layer (40); A first opening (40a) and a second opening (40b) are provided on the insulating protective layer (40); the first pad electrode (51) is filled into the first opening (40a) to be electrically connected to the first type semiconductor layer (11); and the second pad electrode (52) is filled into the second opening (40b) to be electrically connected to the second type semiconductor layer (12).

10. The light emitting diode according to claim 9, characterized in that A first contact electrode (31) is provided between the first pad electrode (51) and the first type semiconductor layer (11); and a second contact electrode (32) is provided between the second pad electrode (52) and the second type semiconductor layer (12).

11. The light emitting diode according to claim 10, characterized in that The bottom width of the first opening (40a) is less than or equal to the bottom width of the first contact electrode, and the bottom width of the second opening (40b) is less than or equal to the bottom width of the second contact electrode (32).

12. The light emitting diode according to claim 9, characterized in that Viewed perpendicularly to the first surface (100), the first pad electrode (51) and the second pad electrode (52) respectively include a partial area overlapping with an area of the active layer (13), or the first pad electrode (51) and the second pad electrode (52) are completely located in an area outside the active layer (13).

13. The light emitting diode according to claim 1, characterized in that It also includes a substrate (50), with a bonding layer (20) provided between the substrate (50) and the epitaxial structure; The bonding layer (20) is a single layer or composite layer structure, and is made of conductive material or insulating material.

14. The light emitting diode according to claim 13, characterized in that The bonding layer (20) has a thickness of 1-5 μm.

15. The light emitting diode according to claim 13, characterized in that The projection shape of the substrate on the plane where the first surface (100) is located is circular, elliptical, or rectangular with rounded corners.

16. A light emitting diode comprising a first surface (100) and a second surface (200) which are relatively upper and lower, wherein the first surface (100) comprises a first side, a second side, a third side, and a fourth side which are connected in sequence, and further comprising: An epitaxial structure comprising a first platform (10a) and a second platform (10b) stacked sequentially from top to bottom, wherein the first platform (10a) comprises at least a first type semiconductor layer (11) and an active layer (13), the second platform (10b) comprises at least a second type semiconductor layer (12), and the upper surface area of the second platform (10b) is greater than or equal to the lower surface area of the first platform (10a); Its characteristics are: The size of the light-emitting diode is less than 300 μm, and at least one side of the projection of the first platform (10a) on the plane where the first surface (100) is located is arc-shaped, and the protruding portion of the arc is closer to the side direction of the arc toward the first surface (100) of the light-emitting diode; A first contact electrode (31) is provided on the first type semiconductor layer (11), the first contact electrode (31) comprising a first point electrode (31a) and two first extensions (31b), the two first extensions (31b) extending from the first point electrode (31a) towards different side directions of the light emitting diode; A second contact electrode (32) is provided on the second-type semiconductor layer (12); the second contact electrode (32) is a point electrode, or the second contact electrode (32) comprises a second point electrode (32a) and two second extensions (32b); the two second extensions (32b) extend from the second point electrode (32a) toward opposite sides of the light-emitting diode; In a plane perpendicular to the first surface (100) of the light-emitting diode and passing through the fourth side, a projection length of the second contact electrode (32) on the plane is smaller than a projection length of the first contact electrode (31) on the plane.

17. A light emitting device, characterized in that: The light emitting diode comprises the light emitting diode according to any one of claims 1 to 16.

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