Light emitting diode and light emitting device

Abstract

The present invention provides a light emitting diode, which includes an epitaxial layer, a first insulating reflective layer and a second insulating reflective layer, wherein the epitaxial layer includes a first semiconductor layer, a light emitting layer for emitting light and a second semiconductor layer stacked in sequence, and has a first surface and a second surface opposite to each other; the first insulating reflective layer is arranged on the first surface of the epitaxial layer; the second insulating reflective layer is arranged on the second surface of the epitaxial layer; wherein the reflectivity of the first insulating reflective layer for light with a first incident angle is lower than the reflectivity of the second insulating reflective layer for light with a third incident angle, the first incident angle is between 0 and 10°, and the third incident angle is between 0 and 10°. With this arrangement, the side light emission angle of the light emitting diode can be greatly improved, the extreme light emission angle of the light emitting diode can be increased, and the market demand can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of light emitting diodes, and in particular to a light emitting diode and a light emitting device with a large light emission angle. 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. Light-emitting diodes have the advantages of low cost, high light efficiency, energy saving and environmental protection, and are widely used in lighting, visible light communication, light-emitting display and other scenarios.

[0003] For backlight applications, Mini LED generally adopts a direct backlight design, which achieves regional dimming in a smaller range through a large number of dense distribution. Compared with traditional backlight design, it can achieve better brightness uniformity and higher contrast within a smaller mixing distance, and does not require additional lenses for secondary light distribution, thereby making the terminal product thinner, with high color rendering and power saving.

[0004] In order to achieve the same light mixing effect and uniformity of light emission, the use of Mini LED chips without large-angle light emission requires a tighter chip arrangement and a larger number of chips; if Mini LED chips with large-angle light emission are used, the chip arrangement will be relatively sparse and the number of chips used will be smaller. Therefore, the use of Mini LED chips with large-angle light emission can greatly reduce the number of Mini LED particles used in the backlight display device, thereby reducing the cost of the backlight display device.

[0005] In order to ensure that the LED chip emits light at a large angle, the current LED chip uses a full-angle reflective layer such as metal vapor deposition, DBR, etc. on the light-emitting surface of the flip-chip LED chip substrate to control the light to be emitted from the side of the chip, so as to increase the chip's light-emitting angle. Although this method can achieve light emission from the side of the chip, since the light emitted from the side of the chip exists in all directions, the extreme angle of light emission is not large enough, so it cannot meet the uniformity requirements. For example: Fig. 9 , Fig.10 As shown, in the existing LED chips with large-angle light emission, the DBR reflective layers on both sides of the substrate have high reflectivity characteristics for light of any incident angle, and the angle of the lateral extreme light emission is about 90°. The ratio of the intensity of the lateral extreme light to the intensity of the axial light is about 2. This lateral light emission angle cannot meet market demand. Summary of the invention

[0006] The invention provides a light emitting diode, which comprises an epitaxial layer, a first insulating reflective layer and a second insulating reflective layer.

[0007] The epitaxial layer includes a first semiconductor layer, a light emitting layer for emitting light, and a second semiconductor layer stacked in sequence, and has a first surface and a second surface opposite to each other. A first insulating reflective layer is disposed on the first surface of the epitaxial layer. A second insulating reflective layer is disposed on the second surface of the epitaxial layer. The reflectivity of the first insulating reflective layer for light with a first incident angle is lower than the reflectivity of the second insulating reflective layer for light with a third incident angle, the first incident angle is between 0 and 10 degrees, and the third incident angle is between 0 and 10 degrees.

[0008] The present invention also provides a light emitting diode, which comprises an epitaxial layer and a first insulating reflective layer.

[0009] The epitaxial layer includes a first semiconductor layer, a light emitting layer for emitting light, and a second semiconductor layer stacked in sequence, and has a first surface and a second surface opposite to each other. The first insulating reflective layer is disposed on the first surface of the epitaxial layer. The reflectivity of the first insulating reflective layer for light with a first incident angle is less than 90%, and the first incident angle is between 0 and 10 degrees.

[0010] The present invention also provides a light emitting diode, which comprises an epitaxial layer and a first insulating reflective layer.

[0011] The epitaxial layer includes a first semiconductor layer, a light emitting layer for emitting light, and a second semiconductor layer stacked in sequence, and has a first surface and a second surface opposite to each other. The first insulating reflective layer is disposed on the first surface of the epitaxial layer. The reflectivity of the first insulating reflective layer for light with a first incident angle is lower than the reflectivity of the first insulating reflective layer for light with a second incident angle, and the first incident angle is smaller than the second incident angle. In one embodiment, the first incident angle is between 0 and 10°, and the second incident angle is between 60 and 90°.

[0012] In one embodiment, the reflectivity of the first insulating reflective layer for light with a first incident angle is less than 90%, and the reflectivity of the first insulating reflective layer for light with a second incident angle is at least 90%, the second incident angle is greater than the first incident angle, and the second incident angle is between 60 and 90°.

[0013] In one embodiment, the reflectivity of the first insulating reflective layer for light with a second incident angle is higher than the reflectivity of the second insulating reflective layer for light with a fourth incident angle, and the second incident angle and the fourth incident angle are between 60° and 80°.

[0014] In one embodiment, the central radiation wavelength of the light emitted by the light emitting layer is between 430 and 460 nanometers.

[0015] In one embodiment, the reflectivity of the second insulating reflective layer for light with a third incident angle is at least 90%.

[0016] In one embodiment, the reflectivity of the second insulating reflective layer for light with a fourth incident angle is lower than 90%, and the fourth incident angle is between 60° and 80°.

[0017] In one embodiment, the first insulating reflective layer and the second insulating reflective layer both include a multilayer structure formed by repeatedly stacking a low-refractive-index material layer and a high-refractive-index material layer.

[0018] In one embodiment, the thickness of the first insulating reflective layer is less than or equal to 4 micrometers, and the thickness of the second insulating reflective layer is less than or equal to 3 micrometers.

[0019] In one embodiment, the reflectivity of the first insulating reflective layer for light with a second incident angle is higher than the reflectivity of the first insulating reflective layer for light with a first incident angle, the second incident angle is greater than the first incident angle, and the second incident angle is between 60° and 90°.

[0020] In one embodiment, the reflectivity of the first insulating reflective layer for light with a first incident angle is lower than 90%, and the reflectivity of the first insulating reflective layer for light with a second incident angle is at least 90%.

[0021] In one embodiment, the light emitting diode further includes a second insulating reflective layer, and the second insulating reflective layer is disposed on the second surface side of the epitaxial layer.

[0022] In one embodiment, the reflectivity of the second insulating reflective layer for light with a third incident angle is at least 90%, and the third incident angle is between 0° and 20°. Preferably, the third incident angle is between 0° and 10°.

[0023] In one embodiment, the reflectivity of the second insulating reflective layer for light with a fourth incident angle is lower than 90%, and the fourth incident angle is between 60° and 80°.

[0024] In one embodiment, the reflectivity of the first insulating reflective layer for light with a first incident angle is lower than 90%, and the reflectivity of the first insulating reflective layer for light with a second incident angle is at least 90%.

[0025] In one embodiment, the light emitting diode further includes a second insulating reflective layer disposed on the second surface of the epitaxial layer, wherein a reflectivity of the second insulating reflective layer for light having a third incident angle is higher than a reflectivity of the second insulating reflective layer for light having a fourth incident angle, the third incident angle is smaller than the fourth incident angle, the third incident angle is between 0 and 20°, and the fourth incident angle is between 60 and 80°.

[0026] In one embodiment, the reflectivity of the second insulating reflective layer for light with a third incident angle is at least 90%, and the reflectivity of the second insulating reflective layer for light with a fourth incident angle is lower than 90%.

[0027] In one embodiment, the light emitting diode is a flip-chip light emitting diode, and a transparent substrate is disposed between the second insulating reflective layer and the epitaxial layer.

[0028] In one embodiment, the light emitting diode is a face-up light emitting diode, and a transparent substrate is disposed between the first insulating reflective layer and the epitaxial layer.

[0029] In one embodiment, the light emitting diode is a flip-chip light emitting diode, and a transparent substrate is disposed on the second surface side of the epitaxial layer.

[0030] The present invention also provides a light emitting device, which uses any of the light emitting diodes described above. In one embodiment, the light emitting device may be a backlight display device.

[0031] The present invention provides a light emitting diode and a light emitting device. By setting a first insulating reflective layer and a second insulating reflective layer to selectively reflect different incident light rays, the axial light emission of the light emitting diode can be reduced, the lateral light emission of the light emitting diode can be increased, the lateral light emission angle of the light emitting diode can be greatly improved, the extreme light emission angle of the light emitting diode can be increased, and the demand for light emission uniformity can be met.

[0032] 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

[0033] 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.

[0034] Figure 1 is a schematic structural diagram of a light emitting diode provided by an embodiment of the present invention;

[0035] Figure 2 is a schematic diagram of light emission of a light emitting diode provided by an embodiment of the present invention;

[0036] Figure 3 It is a schematic structural diagram of a second insulating reflective layer provided by an embodiment of the present invention having a middle area and a peripheral area;

[0037] Figure 4 It is a schematic diagram of the reflectivity of incident light at different angles measured by the first insulating reflective layer and the second insulating reflective layer of a light-emitting diode provided by an embodiment of the present invention;

[0038] Figure 5 yes Figure 4 A schematic diagram of the optical thickness of the first insulating reflective layer shown;

[0039] Figure 6 yes Figure 4 A schematic diagram of the optical thickness of the second insulating reflective layer shown;

[0040] Figure 7 yes Figure 1 The light distribution curve of the light emitting diode shown is obtained by using a distributed photometer to test the light emitting diode;

[0041] Figure 8 is a schematic diagram of the reflectivity of incident light at different angles measured by the first insulating reflective layer and the second insulating reflective layer of a light emitting diode provided by another embodiment of the present invention;

[0042] Fig. 9 It is a schematic diagram of the reflectivity of the double-sided DBR reflective layer of the existing large-angle light-emitting LED chip to incident light at different angles;

[0043] Fig.10 yes Fig. 9 The light distribution curve of the LED chip with large light emission angle is tested by a distributed photometer;

[0044] Fig.11 It is a structural schematic diagram of a front-mounted light emitting diode provided by another embodiment of the present invention.

[0045] Reference numerals:

[0046] 1.5-light-emitting diode; 12-substrate; 14-epitaxial layer; 141-first semiconductor layer; 142-light-emitting layer; 143-second semiconductor layer; 144-first surface; 145-second surface; 16-first insulating reflective layer; 161-first opening; 162-second opening; 18-second insulating reflective layer; 181-middle area; 182-peripheral area; 21-first electrode; 22-second electrode; 31-first pad; 32-second pad; a-first angle of incidence; b-second angle of incidence; c-third angle of incidence; d-fourth angle of incidence. DETAILED DESCRIPTION

[0047] 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.

[0048] 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 a limitation on 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".

[0049] 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.

[0050] The terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "one", "one" and "item" used herein are also intended to include plural numbers. It should also be understood that the terms "include" and / or "comprise" used herein specify the existence of stated features, integers, steps, operations, units and / or components, without excluding the existence or addition of one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0051] See also Figure 1 , Figure 1 1 is a schematic diagram of a light emitting diode 1 provided in an embodiment of the present invention. To achieve at least one of the advantages or other advantages, an embodiment of the present invention provides a light emitting diode 1. As shown in the figure, the light emitting diode 1 includes an epitaxial layer 14, a first insulating reflective layer 16 and a second insulating reflective layer 18.

[0052] The light-transmitting substrate 12 is located between the epitaxial layer 14 and the second insulating reflective layer 18. The epitaxial layer 14 is arranged on the light-transmitting substrate 12, and includes a first semiconductor layer 141, a light-emitting layer 142 and a second semiconductor layer 143 stacked in sequence from bottom to top, and has a first surface 144 and a second surface 145 opposite to each other. The light-transmitting substrate 12 can be a transparent substrate or a semi-transparent substrate, wherein the transparent substrate or the semi-transparent substrate can allow the light radiated by the light-emitting layer 142 to pass through the light-transmitting substrate 12 to reach the side of the light-transmitting substrate 12 away from the epitaxial layer 14. For example, the light-transmitting substrate 12 can be any one of a sapphire flat substrate, a sapphire patterned substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, and a glass substrate. Preferably, the light-transmitting substrate 12 is a sapphire patterned substrate. The light-emitting diode 1 mainly emits light through the side of the light-transmitting substrate 12. The thickness of the light-transmitting substrate 12 can be 60 to 150 microns.

[0053] In this embodiment, the first surface 144 refers to the side of the second semiconductor layer 143 away from the light emitting layer 142, and the second surface 145 refers to the side of the first semiconductor layer 141 away from the light emitting layer 142. In other words, the first surface 144 and the second surface 145 correspond to Figure 1 The lower side and the upper side of the epitaxial layer 14 in the embodiment.

[0054] The first semiconductor layer 141 is formed on the light-transmitting substrate 12. As a layer grown on the light-transmitting substrate 12, it can be a gallium nitride semiconductor layer doped with n-type impurities, such as Si. In some embodiments, an undoped buffer layer is provided between the first semiconductor layer 141 and the light-transmitting substrate 12, and an undoped buffer layer can also be inserted to play a buffering role to avoid the problem of poor quality of the semiconductor layer caused by the large lattice difference between the first semiconductor layer 141 and the light-transmitting substrate 12. In other embodiments, the epitaxial layer 14 can also be connected to the light-transmitting substrate 12 through a bonding layer.

[0055] The light emitting layer 142 may be a quantum well structure (Quantum Well, referred to as QW). In other embodiments, the light emitting layer 142 may 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 arranged in a repeated manner.

[0056] In addition, the composition and thickness of the well layer in the light emitting layer 142 determine the wavelength of the generated light. In particular, by adjusting the composition of the well layer, a light emitting layer 142 that generates different colors of light such as blue light and green light can be provided. In one embodiment, as a light emitting element used in a backlight display, the light emitted by the light emitting layer 142 is blue light, and the central radiation wavelength is between 430 and 460 microns.

[0057] The second semiconductor layer 143 may be a gallium nitride semiconductor layer doped with p-type impurities, such as Mg. Although the first semiconductor layer 141 and the second semiconductor layer 143 may be single-layer structures, the present invention is not limited thereto. The first semiconductor layer 141 and the second semiconductor layer 143 may also be multiple layers, and may also include a superlattice layer. In addition, when the first semiconductor layer 141 is doped with p-type impurities, the second semiconductor layer 143 may be doped with n-type impurities.

[0058] The first insulating reflective layer 16 and the second insulating reflective layer 18 are respectively disposed on the first surface 144 and the second surface 145 of the epitaxial layer 14. The first insulating reflective layer 16 and the second insulating reflective layer 18 both include distributed Bragg reflectors (DBRs). The DBR reflective layer (distributed Bragg reflector) is formed by stacking thin films of different refractive indices alternately and periodically, that is, a periodic thin film composed of a high refractive index material and a low refractive index material alternately arranged. By adjusting the refractive index, thickness and stacking number of each film constituting the DBR reflective layer, the DBR reflective layer can have different transmittance and reflectivity for light with different incident angles. In other words, the first insulating reflective layer 16 and the second insulating reflective layer 18 can be a multilayer structure formed by repeatedly stacking a low refractive index material layer and a high refractive index material layer, so that the first insulating reflective layer 16 and the second insulating reflective layer 18 can have different transmittance and reflectivity according to the change of the incident angle of the light.

[0059] In the prior art, the function of the first insulating layer is to reflect back the light radiated from the epitaxial layer to the first surface side, and to allow the light to radiate mainly from the side of the light-transmitting substrate. The function of the second insulating layer is to reduce the proportion of small-angle light emitting from the front of the substrate and increase the proportion of large-angle light emitting from the side. However, in the prior art, it is not considered that the final light emitting angle range of the chip can be improved by selectively adjusting the light at different angles by the first insulating layer and the second insulating layer, that is, increasing the proportion of lateral light intensity, thereby improving the uniformity of light emission. Based on this, the present invention provides the following design, which achieves the purpose of the present invention by adjusting the reflectivity of the first insulating reflective layer and the second insulating reflective layer to the light generated by the light-emitting layer 142 when powered on and the light radiated to the surface of the first insulating reflective layer and the second insulating reflective layer. Specifically:

[0060] like Figure 2 As shown, for light incident on the surface of the first insulating reflective layer 16 at a small angle, that is, light with a first incident angle a, the reflectivity of the first insulating reflective layer 16 is reduced, that is, the transmittance of the first insulating reflective layer 16 for the light with the first incident angle a is increased. In this way, the first insulating reflective layer 16 transmits at least a portion of the light with a smaller incident angle, thereby reducing the light with a small angle emitted from the surface of the second insulating reflective layer 18 and increasing the light emission ratio of the light with a large angle.

[0061] Preferably, the reflectivity of the first insulating reflective layer 16 for light having a first incident angle a is less than 90%. More preferably, the reflectivity of the first insulating reflective layer 16 is between 50% and 90%. Too low a reflectivity may result in brightness loss. More preferably, the reflectivity is between 60% and 70%, 70% and 80% or 80% and 90%.

[0062] Preferably, the first incident angle a is selected to be in the range of 0 to 10°, which may include axial light with vertical incidence of 0° and light with a small angle greater than 0° and less than or equal to 10° in the range of 0 to 10°. Compared with the conventional insulating reflective layer, the first insulating reflective layer 16 has a lower reflectivity for light with an incident angle in the range of 0 to 10°.

[0063] Preferably, the second insulating reflective layer 18 effectively reflects light with a small incident angle (including light with a vertical incident angle), thereby reducing the proportion of light with a small angle emitted from the surface of the second insulating reflective layer 18 and increasing the proportion of light with a large angle. Light with a small incident angle incident on the surface of the second insulating reflective layer 18 is defined as light with a third incident angle c. Preferably, the reflectivity of the second insulating reflective layer 18 for light with a third incident angle c is high, preferably, its reflectivity is at least 90%, such as 90 to 100%, such as 95%, 96%, 97%, 98% or 99%.

[0064] Preferably, the third incident angle c is between 0 and 20°. That is, the second insulating reflective layer 18 has a high reflectivity for vertically incident axial light at 0° and light at a small angle greater than 0° and less than or equal to 20° in the range of 0 to 20°, and the reflectivity is at least 90%. Preferably, for example, 90 to 100%, for example 95%, 96%, 97%, 98% or 99%. In other words, the reflectivity of the first insulating reflective layer 16 for light with the first incident angle a is lower than the reflectivity of the second insulating reflective layer 18 for light with the third incident angle c, the first incident angle a is between 0 and 10°, and the third incident angle c is between 0 and 20°. More preferably, the third incident angle c is between 0 and 10°.

[0065] Preferably, at least within a small angle range, the first incident angle a and the third incident angle c are both arbitrary angles in the range of 0 to 10°, and the reflectivity of the first insulating reflective layer 16 is lower than the reflectivity of the second insulating reflective layer 18; or more preferably, when the first incident angle a is equal to the third incident angle c, the reflectivity of the first insulating reflective layer 16 is lower than the reflectivity of the second insulating reflective layer 18.

[0066] More preferably, for light incident at a large angle to the surface of the first insulating reflective layer 16, the reflectivity of the first insulating reflective layer 16 maintains the characteristics of a conventional insulating reflective layer, and the reflectivity is relatively high, such as a reflectivity higher than 90%. The first insulating reflective layer 16 reflects light at a relatively large incident angle to the first surface 144 or to the side of the substrate 12, thereby emitting light, which can increase the proportion of light intensity emitted at a large angle, and ensure the overall brightness of the entire light emitting diode 1.

[0067] For the first insulating reflective layer 16, light with a large incident angle is defined as light with a second incident angle b, wherein the first incident angle a is smaller than the second incident angle b, that is, light with the first incident angle a is small-angle light, and light with the second incident angle b is large-angle light.

[0068] Preferably, for light with the second incident angle b, the reflectivity of the first insulating reflective layer 16 is at least 90%. More preferably, the second incident angle b is between 60° and 90°.

[0069] More preferably, the second insulating reflective layer 18 is located on the second surface 145 side, and the light with a large incident angle incident on the surface of the second insulating reflective layer 18 is defined as the light with a fourth incident angle d, and the fourth incident angle d is greater than the third incident angle c, which means that the light with the third incident angle c is a small angle light, and the light with the fourth incident angle d is a large angle light. The reflectivity of the second insulating reflective layer 18 for the light with the third incident angle c is relatively high, and preferably, its reflectivity is at least 90%.

[0070] More preferably, the reflectivity of the first insulating reflective layer 16 for the light with the second incident angle b is higher than the reflectivity of the second insulating reflective layer 18 for the light with the fourth incident angle d. More preferably, the reflectivity of the first insulating reflective layer 16 for the light with the first incident angle a is lower than the reflectivity of the first insulating reflective layer 16 for the light with the second incident angle b.

[0071] More preferably, the reflectivity of the second insulating reflective layer 18 for large-angle light is lower, that is, the transmittance of the second insulating reflective layer 18 for light with a fourth incident angle d is increased, for example, the reflectivity of the second insulating reflective layer 18 for light with a fourth incident angle d is higher than 90%, thereby reducing the length of the light-emitting path of the large-angle light, and increasing the proportion of direct light emission of the large-angle light (so that the large-angle light is directly emitted from the second insulating reflective layer 18 surface), thereby improving the overall brightness of the light-emitting diode 1, preferably, the fourth incident angle d is greater than the second incident angle b, and the fourth incident angle d is between 60 and 80°. The reflectivity of the second insulating reflective layer 18 for light with a fourth incident angle d can be 95%, 96%, 97%, 98% or 99%.

[0072] In general, the amount of light emitted by the light emitting diode 1 in the near vertical direction is reduced, and the proportion of light emitted at a large angle in the near horizontal direction is increased. Finally, the angle range of light emitted from the side of the light emitting diode 1 is improved, increasing the extreme angle of light emission of the light emitting diode 1. In addition, the second insulating reflective layer 18 can also transmit light at a large angle, thereby preventing the light from being reflected back and forth by the DBR reflective layers on both sides, reducing internal light loss.

[0073] It should be noted that for the second insulating reflective layer 18, for light with an incident angle of 0 to 90° between the vertical direction and the horizontal direction, for light with an incident angle between the third incident angle c and the fourth incident angle d, for example, light with an incident angle of 10 to 60°, the second insulating reflective layer 18 may have a reflectivity higher than 90%, or may have a reflectivity lower than 90%. The second insulating reflective layer 18 may be optimized and adjusted according to the actual brightness requirements of the light-emitting diode 1 or the angle range requirements of the emitted light. For example, the range of the third incident angle c may exceed 20°, for example, selected from 0 to 30° or 0 to 40°, and preferably, the range of the third incident angle c does not exceed 50°.

[0074] Similarly, for the first insulating reflective layer 16, for light with an incident angle of 0 to 90° between the vertical direction and the horizontal direction, for light between the first incident angle a and the second incident angle b, such as light with a light angle of 10 to 60°, the first insulating reflective layer 16 may have a reflectivity higher than 90%, or may have a reflectivity lower than 90%. However, it is not limited thereto, and the range of the first incident angle a may also exceed 10°, for example, selected from 0 to 20°, 0 to 30° or 0 to 40°. Preferably, the range of the first incident angle a does not exceed 50°. The first insulating reflective layer 18 may also be optimized and adjusted according to the actual brightness requirements of the light emitting diode 1 or the angle range requirements of the emitted light.

[0075] As a preferred implementation, Figure 2As shown, based on the requirement of light brightness, the reflectivity of the first insulating reflective layer 16 cannot be too low, whether for light at a small angle or for light at a large angle, which will cause serious light loss. Preferably, the reflectivity of the first insulating reflective layer 16 is higher than the transmittance of the first insulating reflective layer 16, or the reflectivity of the first insulating reflective layer 16 for light at any angle exceeds 50%.

[0076] As a preferred implementation, Figure 2 As shown, based on brightness requirements, the reflectivity of the first insulating reflective layer 16 at the first incident angle a is lower than the reflectivity of the first insulating reflective layer 16 at the second incident angle b.

[0077] Through the above-mentioned implementation, the first insulating reflective layer 16 partially transmits light with a smaller incident angle, and the first insulating reflective layer 16 reflects light with a larger incident angle, thereby increasing the proportion of light emitted at a large angle. The second insulating reflective layer 18 reflects light with a smaller incident angle, reflects more light to the first insulating reflective layer 16, and reduces the proportion of small-angle light directly emitted from directly above the substrate 12. The second insulating reflective layer 16 also transmits light with a larger incident angle, further increasing the lateral light emission angle and light emission amount. Finally, the side light emission amount of the light-emitting diode 1 is increased, and the side light emission angle of the light-emitting diode 1 is increased.

[0078] Preferably, for light with the third incident angle c, the reflectivity of the second insulating reflective layer 18 is higher than the transmittance of the second insulating reflective layer 18. For light with the fourth incident angle d, the reflectivity of the second insulating reflective layer 18 may be lower than the transmittance of the second insulating reflective layer 18.

[0079] Preferably, at least within a large angle range, the second incident angle b and the fourth incident angle d are any angles in the range of 60 to 80°, and the reflectivity of the first insulating reflective layer 16 is lower than the reflectivity of the second insulating reflective layer 18; or more preferably, when the second incident angle b and the fourth incident angle d are between 60 and 80°, the reflectivity of the first insulating reflective layer 16 is higher than the reflectivity of the second insulating reflective layer 18.

[0080] In one embodiment, if Figure 3As shown in , the second insulating reflective layer 18 has a relative middle region 181 and a peripheral region 182. For light with a second incident angle b, the transmittance of the second insulating reflective layer 18 in the middle region 181 is lower than the transmittance of the second insulating reflective layer 18 in the peripheral region 182, thereby allowing more light to be emitted from the side of the light-emitting diode 1, thereby increasing the side light emission angle and the side light emission amount of the light-emitting diode 1. Specifically, the transmittance of the middle region 181 can be lower than the transmittance of the peripheral region 182 by changing the thickness of the middle region 181 and the thickness of the peripheral region 182 of the second insulating reflective layer 18; the transmittance of the middle region 181 can also be lower than the transmittance of the peripheral region 182 by performing a graphical treatment on the second insulating reflective layer 18.

[0081] In one embodiment, if Figure 1 , Figure 3 As shown in , the light emitting diode 1 may further include a first electrode 21, a second electrode 22, a first pad 31 and a second pad 32. The first insulating reflective layer 16 is provided with a first opening 161 and a second opening 162. The first electrode 21 and the second electrode 22 are disposed on the first surface 144 of the epitaxial layer 14. The first electrode 21 is electrically connected to the first semiconductor layer 141, and the first pad 31 is electrically connected to the first electrode 21 through the first opening 161. The second electrode 22 is electrically connected to the second semiconductor layer 143, and the second pad 32 is electrically connected to the second electrode 22 through the second opening 162.

[0082] The first electrode 21 and the second electrode 22 may include a reflective metal. For example, the first electrode 21 may include a material such as silver (Ag), nickel (Ni), aluminum (Al), chromium (Cr), rhodium (Rh), palladium (Pd), iridium (Ir), ruthenium (Ru), magnesium (Mg), zinc (Zn), platinum (Pt) or gold (Au), and may have a single-layer structure or may have a structure including two or more layers. The second electrode 22 may include at least one of aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), titanium (Ti) and tin (Sn).

[0083] The first pad 31 and the second pad 32 may include Au, Ag, Al, Ti, W, Cu, Sn, Ni, Pt, Cr, NiSn, TiW, AuSn or eutectic metal thereof. The first pad 31 and the second pad 32 may be formed together using the same material in the same process and thus may have the same layer structure.

[0084] In one embodiment, if Figure 4As shown in the reflection effect, the reflectivity of the first insulating reflective layer 16 for light with a small angle of incidence, that is, light with a first incident angle a, is less than 90%, and the first incident angle a is between 0 and 10°. Preferably, the reflectivity of the first insulating reflective layer 16 for light with an incident angle of less than or equal to 30° is between 80% and 90%. The reflectivity of the first insulating reflective layer 16 for light with a large angle of incidence, that is, light with a second incident angle b, is higher than 90%, and the second incident angle b is between 60 and 90°. Preferably, the reflectivity of the first insulating reflective layer 16 for light with an incident angle of greater than or equal to 60° is higher than 95%. The reflectivity of the second insulating reflective layer 18 for light with a third incident angle c is higher than 90%, preferably, the reflectivity of the second insulating reflective layer 18 for light with an incident angle greater than or equal to 0° and less than or equal to 20° is higher than 95%; the reflectivity of the second insulating reflective layer 18 for light with a fourth incident angle d is lower than 90%, preferably, the reflectivity of the second insulating reflective layer 18 for light with an incident angle greater than or equal to 60° and less than or equal to 80° is lower than 90%. In general, the first insulating reflective layer 16 has a lower reflectivity for light with a small incident angle and a higher reflectivity for light with a large incident angle, and the second insulating reflective layer 18 has a higher reflectivity for light with a small incident angle and a lower reflectivity for light with a large incident angle, thereby improving the side light emission angle of the light emitting diode 1 and increasing the extreme light emission angle of the light emitting diode 1.

[0085] In one embodiment, if Figure 5 , Figure 6 As shown, in order to ensure that the first insulating reflective layer 16 and the second insulating reflective layer 18 can have different transmittance and reflectivity according to different incident angles, the stacking number of the first insulating reflective layer 16 and the second insulating reflective layer 18 can be designed to be less than the stacking number of the general DBR reflective layer, and the thickness is thinner than the thickness of the general DBR reflective layer. For example, the DBR reflective layer can be formed by repeatedly stacking each dielectric film (silicon oxide or titanium oxide) 5 to 15 times.

[0086] Better, such as Figure 5 As shown, due to the improved design of the first insulating reflective layer 16 (usually with a thickness of 2 to 3 microns and a pair number of 15 to 20 pairs), the first insulating reflective layer 16 has a reduced reflectivity for small-angle light, so the thickness of the first insulating reflective layer 16 can be reduced relative to the thickness of the traditional DBR reflective layer. The thickness of the first insulating reflective layer 16 can be between 4 microns and below, that is, the thickness of the first insulating reflective layer 16 can be less than or equal to 4 microns, and the pair number of the dielectric film can be reduced to 12 pairs and below.

[0087] Better, such as Figure 6As shown, the thickness of the second insulating reflective layer 18 can be between 3 microns and below, that is, the thickness of the second insulating reflective layer 18 can be less than or equal to 3 microns, the number of pairs of dielectric layer pairs is 5 to 15 pairs, the first insulating reflective layer 16 is thicker than the second insulating reflective layer 18, and the number of pairs of the first insulating reflective layer 16 is greater than the second insulating reflective layer 18. The DBR reflective layer structure (i.e., the first insulating reflective layer 16 and the second insulating reflective layer 18) designed with optical thickness can allow the first insulating reflective layer 16 and the second insulating reflective layer 18 to have different reflectivities and transmittances for light with different incident angles.

[0088] In one embodiment, if Figure 7 As shown, by means of the selective reflection of the first insulating reflective layer 16 and the second insulating reflective layer 18 for light at different incident angles, the angle of the lateral extreme light emission is about 120°, and the ratio of the light intensity of the lateral extreme light to the light intensity of the axial light is about 3.3, so that a large amount of light is emitted from the side of the side light emitting diode 1, increasing the side light emission angle and the extreme light emission angle, thereby making the light distribution formed by the light emitted by the light emitting diode 1 in the shape of a bat wing.

[0089] In one embodiment, if Figure 8 The reflection effect shown can effectively improve the side light output angle of the light emitting diode and increase the extreme light output angle of the light emitting diode only by the first insulating reflective layer 16 having different reflectivities for light with different incident angles. Specifically, the reflectivity of the first insulating reflective layer 16 for light with a first incident angle a is lower than 90%, and preferably, the reflectivity of the first insulating reflective layer 16 for light with an incident angle less than or equal to 10° is between 80% and 90%; the reflectivity of the first insulating reflective layer 16 for light with a second incident angle b is higher than 90%, and preferably, the reflectivity of the first insulating reflective layer 16 for light with an incident angle greater than or equal to 60° is higher than 95%. The second insulating reflective layer 18 maintains a high reflectivity for light with any incident angle, and its reflectivity can be higher than 95%, and preferably, the reflectivity of the second insulating reflective layer 18 is close to 100%. The first insulating reflective layer 16 has a lower reflectivity for small-angle incident light and a higher reflectivity for large-angle incident light. The high reflectivity of the second insulating reflective layer 18 can improve the side light output angle of the LED and increase the extreme light output angle of the LED. Figure 8 The reflectivity of the first insulating reflective layer 16 and the second insulating reflective layer 18 for a larger incident angle is close to 100%, so the second half of the line segment in the figure overlaps. In addition, the angle of the lateral extreme light in this embodiment is about 115°, and the ratio of the light intensity of the lateral extreme light to the light intensity of the axial light is about 2.5.

[0090] It should be supplemented that the first insulating reflective layer 16 and the second insulating reflective layer 18 are not limited to DBR reflective layers, and may also be other reflective structures that can have different reflectivities and transmittances according to different incident angles.

[0091] An embodiment of the present invention may further provide a light emitting device, which uses the light emitting diode 1 provided by any of the above embodiments, and its specific structure and technical effects are not described in detail.

[0092] Preferably, the light emitting diode 1 can be applied to the field of direct backlight display, and the small-sized flip-chip light emitting diodes 1 are integrated in the number of hundreds, thousands or tens of thousands and mounted on the application substrate or the packaging substrate in a flip-chip manner (for example, the substrate is connected by the tin element of the solder paste or the pad electrode of the light emitting diode 1 itself), forming the light source part of the backlight display device. The small size can be a miniLED chip with an area of ​​less than 90,000 square microns.

[0093] In summary, the light-emitting diode 1 and the light-emitting device provided by the present invention can reduce the axial light emission of the light-emitting diode 1, increase the lateral light emission of the light-emitting diode 1, improve the side light emission angle of the light-emitting diode 1, and increase the extreme light emission angle of the light-emitting diode 1, thereby meeting market demand, through the setting of the selective reflection of different incident light rays by the first insulating reflective layer 16 and the second insulating reflective layer 18.

[0094] In addition, as an alternative embodiment, Fig.11 As shown, the light emitting diode 5 can also be a regular size regular light emitting diode 5, which is a miniLED light emitting diode with an area greater than 90,000 square microns. Figure 1 Compared with the flip-chip structure light emitting diode 1 shown, the light-transmitting substrate 12 of the upright light emitting diode 5 is located between the first insulating reflective layer 16 and the epitaxial layer 14. Moreover, since it is an upright light emitting diode 5, there is no need to set the first solder pad 31 and the second solder pad 32. The first electrode 21 and the second electrode 22 are exposed through the first opening 161 and the second opening 162, respectively, so as to facilitate wire connection in the subsequent manufacturing process. Preferably, the upright structure light emitting diode 5 can be applied to the field of direct-type backlight display or the field of edge-type backlight display. The upright light emitting diodes of conventional size are installed in an integrated manner (wire bonding method, such as gold wire) in the number of dozens or hundreds on the application substrate or the packaging substrate to form the light source part of the backlight display device.

[0095] It should be noted that the reflectivity curves of the present invention are obtained by the following method: a glass substrate (BK7 glass replaces the epitaxial layer structure) is used as a medium, the thickness of the glass substrate is 1 mm, a titanium oxide film and a silicon oxide film are plated on one side of the glass substrate as an insulating reflective film formed by alternating high and low refractive index films as a test object, a reflectivity tester provides a light source with a light emission wavelength of 444 nm (the central wavelength of light emitting diode radiation), the light radiated by the light source is incident from the glass substrate and reaches the interface between the glass substrate and the insulating reflective film, then is reflected by the insulating reflective film and emitted from the glass substrate to be collected, and the reflectivity tester tests the light reflectivity of the insulating reflective film. The reflectivity of the insulating reflective layer can also be obtained using optical thin film analysis and design software, such as the software named Essential Macleod.

[0096] 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.

[0097] 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: The epitaxial layer comprises a first semiconductor layer, a light-emitting layer for emitting light, and a second semiconductor layer stacked in sequence, and has a first surface and a second surface opposite to each other, wherein the first surface refers to a side of the second semiconductor layer away from the light-emitting layer, and the second surface refers to a side of the first semiconductor layer away from the light-emitting layer; A first insulating reflective layer, disposed on a first surface side of the epitaxial layer; A second insulating reflective layer is disposed on the second surface side of the epitaxial layer; A light-transmitting substrate, located between the epitaxial layer and the second insulating reflective layer; Among them, the reflectivity of the first insulating reflective layer for light with a first incident angle is lower than the reflectivity of the second insulating reflective layer for light with a third incident angle, the first incident angle is between 0 and 10°, the third incident angle is between 0 and 10°, and the second surface is a light emitting surface.

2. The light emitting diode according to claim 1, characterized in that: The reflectivity of the first insulating reflective layer for light with the first incident angle is lower than 90%, and the reflectivity of the first insulating reflective layer for light with a second incident angle is at least 90%, the second incident angle is greater than the first incident angle, and the second incident angle is between 60 and 90 degrees.

3. The light emitting diode according to claim 2, characterized in that: The reflectivity of the first insulating reflective layer for light with the second incident angle is higher than the reflectivity of the second insulating reflective layer for light with a fourth incident angle, and the second incident angle and the fourth incident angle are between 60° and 80°.

4. The light emitting diode according to claim 2, characterized in that: The central radiation wavelength of the light emitted by the light emitting layer is between 430 and 460 nanometers.

5. The light emitting diode according to claim 2, characterized in that: The reflectivity of the second insulating reflective layer for light with the third incident angle is at least 90%.

6. The light emitting diode according to claim 2, characterized in that: The reflectivity of the second insulating reflective layer for light with a fourth incident angle is lower than 90%, and the fourth incident angle is between 60° and 80°.

7. The light emitting diode according to claim 1, characterized in that: The first insulating reflective layer and the second insulating reflective layer both include a multilayer structure formed by repeatedly stacking a low-refractive index material layer and a high-refractive index material layer.

8. The light emitting diode according to claim 1, characterized in that: The thickness of the first insulating reflective layer is less than or equal to 4 micrometers, and the thickness of the second insulating reflective layer is less than or equal to 3 micrometers.

9. A light emitting device, characterized in that: A light emitting diode as claimed in any one of claims 1 to 8 is used.

10. The light emitting device according to claim 9, characterized in that: The light emitting device is a backlight display device.

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