Light emitting element

Abstract

The present invention discloses a light-emitting element comprising a substrate; a semiconductor stack capable of emitting light having a peak wavelength λ, located on the substrate; and a light field adjustment layer located on the substrate or the semiconductor layer, wherein the light field adjustment layer comprises a plurality of first layers and a plurality of second layers alternately stacked on top of each other, each of the plurality of first layers comprising a first optical thickness, and each of the plurality of second layers comprising a second optical thickness.

Description

Technical Field

[0001] This invention relates to a light-emitting element, and more particularly to a light-emitting element comprising a light field adjustment layer. Background Technology

[0002] Light-emitting diodes (LEDs) are solid-state semiconductor light-emitting devices. Their advantages include low power consumption, low heat generation, long lifespan, shock resistance, small size, fast response speed, and excellent photoelectric properties, such as a stable emission wavelength. Therefore, LEDs are widely used in household appliances, equipment indicator lights, and optoelectronic products. Summary of the Invention

[0003] According to an embodiment of the present invention, a light-emitting element is disclosed, comprising a substrate; a semiconductor stack capable of emitting light having a peak wavelength λ, located on the substrate; and a light field adjustment layer located on the substrate or the semiconductor layer, wherein the light field adjustment layer comprises a plurality of first layers and a plurality of second layers alternately stacked on top of each other, each of the plurality of first layers comprising a first optical thickness, and each of the plurality of second layers comprising a second optical thickness.

[0004] According to one embodiment of the present invention, the first optical thickness is less than 0.25λ, and the second optical thickness is greater than or approximately equal to 0.25λ.

[0005] According to one embodiment of the present invention, the first optical thickness is approximately equal to 0.25λ, and the second optical thickness is less than or greater than 0.25λ.

[0006] According to one embodiment of the present invention, the first optical thickness is greater than 0.25λ, and the second optical thickness is less than or approximately equal to 0.25λ.

[0007] According to another embodiment of the present invention, a light-emitting element is disclosed, comprising a substrate; a semiconductor stack capable of emitting light having a peak wavelength λ, located on the substrate; and a light field adjustment layer located on the substrate or the semiconductor layer, wherein the light field adjustment layer comprises a plurality of first layers, a plurality of second layers, and a space layer located between two adjacent plurality of first layers or between two adjacent plurality of second layers, wherein the space layer comprises an optical thickness that is an even multiple of 0.25 + / - 0.025λ. Attached Figure Description

[0008] Figure 1 This is a side view of a light-emitting element 1 disclosed in an embodiment of the present invention;

[0009] Figure 2A This is a light emission spectrum of a light-emitting element 1 according to an embodiment of the present invention;

[0010] Figure 2B This is an embodiment of the present invention. Figure 1 A magnified view of part of region A;

[0011] Figure 2C Another embodiment of the present invention Figure 1 A magnified view of part of region A;

[0012] Figure 3A This is a schematic diagram of light propagation according to an embodiment of the present invention;

[0013] Figure 3B This is a schematic diagram of light propagation according to an embodiment of the present invention;

[0014] Figure 3C This is a light field distribution diagram of the light-emitting element 1 disclosed in an embodiment of the present invention;

[0015] Figure 4 The light field distribution diagram of existing light-emitting elements;

[0016] Figures 5A-5B This is a diagram showing the optical thickness variation of the light field adjustment layer 30 according to an embodiment of the present invention;

[0017] Figures 6A-6B This is a diagram showing the optical thickness variation of the light field adjustment layer 30 according to an embodiment of the present invention;

[0018] Figures 7A-7B This is a diagram showing the optical thickness variation of the light field adjustment layer 30 according to an embodiment of the present invention;

[0019] Figure 8 This is a diagram showing the optical thickness variation of the light field adjustment layer 30 according to an embodiment of the present invention;

[0020] Figure 9 This is a schematic diagram of a light-emitting device 100 according to an embodiment of the present invention;

[0021] Figure 10 This is a schematic diagram of a backlight module 7 according to an embodiment of the present invention;

[0022] Figure 11 This is a schematic diagram of a display 8 according to an embodiment of the present invention.

[0023] Symbol Explanation

[0024] 1: Light-emitting element

[0025] 10: Substrate

[0026] 20: Semiconductor stack

[0027] 21: First semiconductor layer

[0028] 22: Second semiconductor layer

[0029] 23: Active layer

[0030] 30: Light Field Adjustment Layer

[0031] 30a: First layer

[0032] 30b: Second layer

[0033] 30c: Space layer

[0034] 40: Transparent conductive layer

[0035] 41: Reflective layer

[0036] 50: Protective layer

[0037] 51: Insulation layer

[0038] 61: First electrode

[0039] 62: Second electrode

[0040] 71: First electrode pad

[0041] 72: Second electrode pad

[0042] 100: Light-emitting device

[0043] 101: First Page

[0044] 102: Second Page

[0045] 511: Opening of the first insulating layer

[0046] 512: Opening of the second insulation layer

[0047] 1001: Circuit Board

[0048] 1002a: First external electrode

[0049] 1002b: Second external electrode

[0050] 1004a: First Welding Section

[0051] 1004b: Second Welding Section

[0052] θi: Angle of incidence

[0053] θj: Angle of departure

[0054] θ1: First region

[0055] θ2: Second region

[0056] L: Light Detailed Implementation

[0057] To make the description of the present invention more detailed and complete, please refer to the following description of the embodiments and related illustrations. However, the embodiments shown below are for illustrating the light-emitting element of the present invention and are not intended to limit the present invention to the following embodiments. Furthermore, the dimensions, materials, shapes, relative arrangements, etc., of the constituent parts described in the embodiments in this specification are not limited thereto, and the scope of the present invention is not limited thereto, but is merely illustrative. Also, the size or positional relationships of the components shown in the illustrations may be exaggerated for clarity. Furthermore, in the following description, for the sake of appropriate omission of detailed descriptions, components of the same or similar nature are shown with the same name and symbol.

[0058] Figure 1 This is a side view of a light-emitting element 1 disclosed in an embodiment of the present invention. Figure 2A This is a light emission spectrum of a light-emitting element 1 according to an embodiment of the present invention. Figure 2B This is an embodiment of the present invention. Figure 1 A magnified view of part of region A. Figure 2C This is another embodiment of the present invention. Figure 1 A magnified view of part of region A.

[0059] like Figure 1 As shown, a light-emitting element 1 includes a substrate 10; a semiconductor stack 20 is located on the substrate 10, including a first semiconductor layer 21, a second semiconductor layer 22 and an active layer 23 located between the first semiconductor layer 21 and the second semiconductor layer 22; a transparent conductive layer 40 is located on the semiconductor stack 20; a protective layer 50 covers the semiconductor stack 20; and a light field adjustment layer 30 is located on the substrate 10 or the semiconductor stack 20.

[0060] The substrate 10 can be a growth substrate for epitaxially growing a semiconductor stack 20. The substrate 10 includes gallium arsenide (GaAs) wafers for epitaxially growing aluminum gallium indium phosphide (AlGaInP), or sapphire (Al2O3) wafers, gallium nitride (GaN) wafers, silicon carbide (SiC) wafers, or aluminum gallium nitride (AlGaN) wafers for growing gallium nitride (GaN), indium gallium nitride (InGaN), or aluminum gallium nitride (AlGaN).

[0061] The substrate 10 includes a first surface 101 and a second surface 102. In this embodiment, the first surface 101 is the main light-emitting surface of the light-emitting element 1. A light field adjustment layer 30 is disposed on the first surface 101 of the substrate 10, and selectively reflects and transmits light emitted from the semiconductor stack 20 with a peak wavelength λ, causing the light transmittance to vary with the incident angle, thereby adjusting the light field distribution of the light-emitting element 1. Figure 2AAs shown, the semiconductor stack 20 of the light-emitting element 1 emits light with a wavelength range of 430 nm to 470 nm, where the peak wavelength λ is the wavelength of the maximum relative light intensity, for example, 450 nm.

[0062] The substrate 10 is in contact with the semiconductor stack 20 via a second surface 102. The second surface 102 can be a roughened surface. The roughened surface includes a surface with an irregular shape or a surface with a regular shape. For example, relative to the second surface 102, the substrate 10 includes one or more protrusions (not shown) protruding from the second surface 102, or one or more recesses (not shown) recessed into the second surface 102. In a cross-sectional view, the protrusions (not shown) or recesses (not shown) can be semi-circular or polygonal.

[0063] In one embodiment of the present invention, a semiconductor stack 20 with photoelectric properties, such as a light-emitting stack, is formed on a substrate 10 by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydride vapor deposition (HVPE), physical vapor deposition (PVD), or ion plating. The physical vapor deposition method includes sputtering or evaporation.

[0064] The semiconductor stack 20 includes a first semiconductor layer 21, a second semiconductor layer 22, and an active layer 23 formed between the first semiconductor layer 21 and the second semiconductor layer 22. The wavelength of light emitted by the light-emitting element 1 can be adjusted by changing the physical and chemical composition of one or more layers in the semiconductor stack 20. The material of the semiconductor stack 20 includes group III-V semiconductor materials, such as Al. x In y Ga (1-x-y) N, Al x Ga (1-x) As or Al x In y Ga (1-x-y) P, where 0≤x, y≤1; (x+y)≤1. When the material of the semiconductor stack 20 is AlGaAs or AlInGaP series material, it can emit red light with wavelengths between 610 nm and 650 nm, or green light with wavelengths between 530 nm and 570 nm. When the material of the semiconductor stack 20 is InGaN series material, it can emit blue or deep blue light with wavelengths between 400 nm and 490 nm, or green light with wavelengths between 490 nm and 550 nm. When the material of the semiconductor stack 20 is AlGaN series or AlInGaN series material, it can emit ultraviolet light with wavelengths between 250 nm and 400 nm.

[0065] The first semiconductor layer 21 and the second semiconductor layer 22 can be cladding layers, having different conductivity types, electrical properties, and polarities, or depending on the doped elements that provide electrons or holes. For example, the first semiconductor layer 21 can be an n-type semiconductor, and the second semiconductor layer 22 can be a p-type semiconductor. An active layer 23 is formed between the first semiconductor layer 21 and the second semiconductor layer 22. Electrons and holes recombine in the active layer 23 under the drive of a current, converting electrical energy into light energy to emit light. The active layer 23 can be a single heterostructure (SH), a double heterostructure (DH), a double-side double heterostructure (DH), or a multi-quantum well (MQW). The material of the active layer 23 can be a neutral, p-type, or n-type semiconductor. The first semiconductor layer 21, the second semiconductor layer 22, or the active layer 23 can be a single-layer structure or a multi-layer structure.

[0066] In one embodiment of the present invention, the semiconductor stack 20 may further include a buffer layer (not shown) located between the first semiconductor layer 21 and the substrate 10 to release stress caused by material lattice mismatch between the substrate 10 and the semiconductor stack 20, thereby reducing misalignment and lattice defects and improving epitaxial quality. The buffer layer may be a single layer or a multilayer structure. In one embodiment, PVD aluminum nitride (AlN) may be used as the buffer layer, formed between the semiconductor stack 20 and the substrate 10, to improve the epitaxial quality of the semiconductor stack 20. In one embodiment, the target material used to form PVD aluminum nitride (AlN) is composed of aluminum nitride. In another embodiment, an aluminum target material may be used, which reacts with the aluminum target material in a nitrogen source environment to form aluminum nitride.

[0067] To reduce contact resistance and improve current diffusion efficiency, the light-emitting element 1 includes a transparent conductive layer 40 located on the second semiconductor layer 22. The transparent conductive layer 40 is made of a metallic material or a transparent conductive oxide having a thickness of less than 500 angstroms (Å). The metallic material includes chromium (Cr), titanium (Ti), tungsten (W), gold (Au), aluminum (Al), indium (In), tin (Sn), nickel (Ni), platinum (Pt), or alloys of the above materials. The transparent conductive oxide includes indium tin oxide (ITO) or indium zinc oxide (IZO).

[0068] The light-emitting element 1 includes a first electrode 61 and a second electrode 62 formed on the same side of the semiconductor stack 20. The light-emitting element 1 can be a flip-chip structure or a lateral chip structure. When the light-emitting element 1 is a flip-chip structure, such as... Figure 1 As shown, the light field adjustment layer 30 is disposed on the first surface 101 of the substrate 10. When the light-emitting element 1 has a horizontal chip structure, the light field adjustment layer 30 can be disposed on the semiconductor stack 20, for example, between the semiconductor stack 20 and the first electrode 61 and the second electrode 62 (not shown). The light field adjustment layer 30 is disposed on the main light-emitting surface of the light-emitting element 1, and adjusts the light field distribution of the light-emitting element 1 by adjusting the reflectivity and transmittance of light incident on the main light-emitting surface.

[0069] When the light-emitting element 1 is a flip chip structure, such as Figure 1 As shown, to increase the light emission efficiency of the light-emitting element 1, the light-emitting element 1 may include a reflective layer 41 to reflect the light generated by the active layer 23 of the semiconductor stack 20, and to allow the reflected light to be emitted outward toward the substrate 10. The reflective layer 41 includes a metal reflective layer or an insulating reflective structure. When the reflective layer 41 is a metal reflective layer, its material includes metals such as aluminum (Al), silver (Ag), rhodium (Rh), or platinum (Pt), or alloys of the above materials. In one embodiment, to avoid oxidation of the surface of the metal reflective layer, thereby degrading the reflectivity of the metal reflective layer, a barrier layer (not shown) may be formed on the metal reflective layer to cover the upper surface and side surface of the metal reflective layer. The material of the barrier layer (not shown) includes metallic materials, such as titanium (Ti), tungsten (W), aluminum (Al), indium (In), tin (Sn), nickel (Ni), chromium (Cr), platinum (Pt), or alloys of the above materials. The barrier layer can be a one- or multi-layer structure, such as titanium (Ti) / aluminum (Al) and / or nickel-titanium alloy (NiTi) / titanium-tungsten alloy (TiW). When the reflective layer 41 is an insulating reflective layer, it comprises two or more insulating materials with different refractive indices stacked alternately to form a distributed Bragg reflector (DBR) structure. In one embodiment of the invention, when the reflective layer 41 is an insulating reflective layer, it may include one or more perforations (not shown), and the second electrode 62 forms an electrical connection with the transparent conductive layer 40 through one or more perforations of the insulating reflective layer. In one embodiment of the invention, the second electrode 62 comprises a reflective metallic material, which can be combined with the insulating reflective layer to form an omni-directional reflector.

[0070] In one embodiment of the present invention, when the light-emitting element 1 is a horizontal chip structure, the reflective layer 41 may be disposed on the first surface 101 of the substrate 10.

[0071] In one embodiment of the present invention, the light-emitting element 1 includes an insulating layer 51 located on a first electrode 61 and a second electrode 62; a first electrode pad 71 located on the insulating layer 51; and a second electrode pad 72 located on the insulating layer 51. The insulating layer 51 includes a first insulating layer opening 511 to expose the first electrode 61; and a second insulating layer opening 512 to expose the second electrode 62. The first electrode pad 71 contacts the first electrode 61 and is electrically connected to the first semiconductor layer 21 through the first insulating layer opening 511. The second electrode pad 72 contacts the second electrode 62 and is electrically connected to the second semiconductor layer 22 through the second insulating layer opening 512.

[0072] The first electrode 61, the second electrode 62, the first electrode pad 71, and the second electrode pad 72 comprise metallic materials, such as chromium (Cr), titanium (Ti), tungsten (W), gold (Au), aluminum (Al), indium (In), tin (Sn), nickel (Ni), platinum (Pt), or alloys thereof. The first electrode 61, the second electrode 62, the first electrode pad 71, and the second electrode pad 72 may consist of a single layer or multiple layers. For example, the first electrode 61, the second electrode 62, the first electrode pad 71, and the second electrode pad 72 may include a Ti / Au layer, a Ti / Pt / Au layer, a Cr / Au layer, a Cr / Pt / Au layer, a Ni / Au layer, a Ni / Pt / Au layer, or a Cr / Al / Cr / Ni / Au layer. The first electrode 61, the second electrode 62, the first electrode pad 71, and the second electrode pad 72 can serve as current paths for supplying power from an external power source to the first semiconductor layer 21 and the second semiconductor layer 22. The first electrode 61, the second electrode 62, the first electrode pad 71, and the second electrode pad 72 each have a thickness between 1 and 100 μm, preferably between 1.2 and 60 μm, and more preferably between 1.5 and 6 μm.

[0073] The protective layer 50 and the insulating layer 51 are made of non-conductive materials. Non-conductive materials include organic, inorganic, or dielectric materials. Organic materials include Su8, benzocyclobutene (BCB), perfluorocyclobutane (PFCB), epoxy resin, acrylic resin, cyclic olefin polymer (COC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyetherimide, or fluorocarbon polymer. Inorganic materials include silicone or glass. Dielectric materials include alumina (Al2O3), silicon nitride (SiN), and silicon oxide (SiO2). x ), silicon oxynitride (SiO) x N y Titanium oxide (TiO) x ) or magnesium fluoride (MgF)x In one embodiment of the invention, the protective layer 50 and / or the insulating layer 51 may be a single-layer structure. In a variation of the invention, the protective layer 50 and / or the insulating layer 51 may be formed into a multilayer protective layer or insulating layer by combining the above-described materials, for example, by alternately stacking two or more materials with different refractive indices to form a reflective structure including a distributed Bragg mirror (DBR). The protective layer 50 and / or the insulating layer 51 preferably has a thickness of 0.5 μm to 4 μm, more preferably a thickness of 2.5 μm to 3.5 μm, and even more preferably a thickness of 2.7 μm to 3.3 μm.

[0074] In one embodiment where the protective layer 50 and / or insulating layer 51 comprises a distributed Bragg reflector (DBR) structure, the protective layer 50 and / or insulating layer 51 have a reflectivity of over 90% for light emitted from the semiconductor stack 20 having a peak wavelength λ. When light enters the protective layer 50 and / or insulating layer 51 at a right angle or at various incident angles, the protective layer 50 and / or insulating layer 51 exhibit good reflectivity to improve luminous efficiency.

[0075] In one embodiment where the protective layer 50 and / or insulating layer 51 includes a distributed Bragg reflector (DBR) structure, the DBR structure may include multiple regions, such as a first region and a second region. The first region is closest to the semiconductor stack 20, and the second region is farther away from the semiconductor stack 20. The first and second regions each have multiple film layers. The multiple film layers in the first and second regions are formed by alternating stacks of film layers made of two or more materials with different refractive indices. In one embodiment, the first and second regions are formed by alternating stacks of a third layer and a fourth layer made of two materials, respectively. The material of the third layer has a third refractive index (low refractive index), such as a SiO2 layer (n: about 1.47), and the material of the fourth layer has a fourth refractive index (high refractive index), such as a TiO2 layer (n: about 2.41). In one embodiment, the third and fourth layers of the first region each have a third optical thickness and a fourth optical thickness, respectively, and the third optical thickness and the fourth optical thickness are both greater than 0.25λ. The third and fourth layers of the second region each have a third optical thickness and a fourth optical thickness, respectively, both less than 0.25λ. In one embodiment, there are one or more other regions, such as a third and a fourth region, between the first and second regions, with the third region closer to the first region than the fourth region. The third and fourth regions each have multiple film layers. These multiple film layers are formed by alternating stacks of film layers composed of two or more materials with different refractive indices. In one embodiment, similar to the first and second regions, the third and fourth regions are formed by alternating stacks of third and fourth layers composed of two materials. The material of the third layer has a third refractive index (low refractive index), such as a SiO2 layer (n: about 1.47), and the material of the fourth layer has a fourth refractive index (high refractive index), such as a TiO2 layer (n: about 2.41). In one embodiment, the third and fourth layers of the third region each have a third optical thickness and a fourth optical thickness; the third and fourth layers of the fourth region each have a third optical thickness and a fourth optical thickness. The third and fourth optical thicknesses of the third and fourth regions are respectively less than and greater than the third and fourth optical thicknesses of the first region and the second region, respectively, and the third and fourth optical thicknesses of the third region are greater than or equal to the third and fourth optical thicknesses of the fourth region. In one embodiment, the third and fourth optical thicknesses of the third region are respectively greater than 0.25λ, and the third and fourth optical thicknesses of the fourth region are respectively greater than 0.25λ. In one embodiment, the third and fourth optical thicknesses of the third region are respectively greater than 0.25λ, and the third and fourth optical thicknesses of the fourth region are respectively less than 0.25λ. In one embodiment, the third and fourth optical thicknesses of the third region are respectively less than 0.25λ, and the third and fourth optical thicknesses of the fourth region are respectively less than 0.25λ.In one embodiment, the third optical thickness and the fourth optical thickness of the third region are both equal to 0.25λ, and the third optical thickness and the fourth optical thickness of the fourth region are both equal to 0.25λ.

[0076] The optical thickness difference between two adjacent third and fourth material layers in each region is less than 0.05λ, and more preferably less than 0.025λ. The optical thickness is the product of the physical thickness and the refractive index (n) of the material layer.

[0077] The light field adjustment layer 30 is disposed on the main emitting surface of the light-emitting element 1, and adjusts the light field distribution of the light-emitting element 1 by reflecting light in a direction perpendicular to the main emitting surface. The light field adjustment layer 30 comprises two or more materials with different refractive indices stacked alternately to form a Bragg mirror (DBR) structure, which selectively reflects light of a specific wavelength and makes the light transmittance vary according to its incident angle.

[0078] The main light-emitting surface of the light-emitting element 1 depends on its structure; it can emit light from one side of the substrate 10 or from one side of the first electrode 61 and the second electrode 62. When the light-emitting element 1 has a flip-chip structure, such as... Figure 1 As shown, the light field adjustment layer 30 is disposed on the first surface 101 of the substrate 10. When the light-emitting element 1 has a lateral chip structure, the light field adjustment layer 30 can be disposed between the semiconductor stack 20 and the first electrode 61 and the second electrode 62 (not shown).

[0079] Taking the light-emitting element 1 as a flip chip structure as an example, according to Snell's law, such as Figure 3A As shown, due to the changes in the refractive index of each material encountered by the light ray L as it travels from the semiconductor stack through the substrate 10 and the light field adjustment layer 30 and is emitted into the air, the exit angle θj of the light ray L after passing through the light field adjustment layer 30 is greater than the incident angle θi of the light ray L when it is incident on the light field adjustment layer 30.

[0080] Specifically, such as Figure 3B and Figure 3C As shown, when light L is incident on the light field adjustment layer 30 at an incident angle less than θi and exits through the light field adjustment layer 30, it will have a first light intensity in the first region θ1; when light L is incident on the light field adjustment layer 30 at an incident angle greater than θi and exits through the light field adjustment layer 30, it will have a second light intensity in the second region θ2. The light field adjustment layer 30 has a transmittance of less than 50% for light with an incident angle less than θi, so the light-emitting element 1 has a batwing-shaped light field distribution.

[0081] like Figure 3CAs shown, the light ray L has the highest transmittance near the exit angle of 60 to 70 degrees, and maintains a relatively high overall transmittance in the angle range of 30 to 80 degrees.

[0082] Figure 4 This is a light field distribution diagram of an existing light-emitting element without the light field adjustment layer 30. (Compared to...) Figure 4 In comparison, by Figure 3C It can be seen that the amount of light L decreases significantly between 0 and 30 degrees, while the amount of light increases relatively between 30 and 90 degrees.

[0083] By replacing the lens with the optical structure of the light field adjustment layer 30, the optical distribution can be adjusted at the wafer level or on the chip, avoiding the need for additional lens optical structures.

[0084] like Figure 2B and Figure 2C As shown, the light field adjustment layer 30 comprises two dielectric films with different refractive indices stacked alternately multiple times, such as a first layer 30a and a second layer 30b. Figure 3B and Figure 3C As shown, the user can adjust the light field adjustment layer 30 to reduce the transmittance of light rays with an incident angle less than a specific incident angle θi and increase the transmittance of light rays with an incident angle greater than a specific incident angle θi, thereby adjusting the distribution of the batwing-shaped light field. For example, light ray L within the light field adjustment layer 30 includes light incident at a first incident angle (not shown) and a second incident angle (not shown). When light rays exit from the light field adjustment layer 30, if the second incident angle is greater than the specific incident angle θi and the first incident angle is less than the specific incident angle θi, the transmittance of light ray L at the second incident angle is greater than the transmittance at the first incident angle, thus achieving a batwing-shaped light field distribution.

[0085] In this embodiment, the transmittance of light L at each incident angle is adjusted by selecting the refractive index, thickness T1 and T2 of the first layer 30a and the second layer 30b of the light field adjustment layer 30 and the number of layers stacked.

[0086] Specifically, an optical field adjustment layer 30 is formed by repeatedly stacking a first layer 30a and a second layer 30b with different refractive indices 2 to 50 times. The thickness of the optical field adjustment layer 30, that is, the sum of the first optical thickness T1 and the second optical thickness T2 of the multiple first layers 30a and the multiple second layers 30b, can be designed to be 0.5 μm to 5 μm, preferably 1 μm to 3 μm, and more preferably 1.5 μm to 2 μm.

[0087] One of the first layer 30a and the second layer 30b of the light field adjustment layer 30 is a high refractive index layer, such as TiO2. xThe materials used in the optical field adjustment layer 30 are HfO2, ZnO, La2O3, CeO2, ZrO2, ZnSe, Si3N4, Nb2O5, or Ta2O5, and the other layer of the first layer 30a and the second layer 30b of the optical field adjustment layer 30 is a low refractive index layer, such as SiO2, LaF3, MgF2, NaF, Na3AlF6, CaF2, or AlF3.

[0088] In one embodiment of the invention, the first and / or last layer of the light field adjustment layer 30 comprises TiO2. x , HfO2, ZnO, La2O3, CeO2, ZrO2, ZnSe, Si3N4, Nb2O5 or Ta2O5.

[0089] In another embodiment of the invention, the first and / or last layer of the light field adjustment layer 30 comprises SiO2, LaF3, MgF2, NaF, Na3AlF6, CaF2 or AlF3.

[0090] In another embodiment of the invention, the light field adjustment layer 30 further includes a first initiation layer (not shown) and a second initiation layer (not shown) located between the first layer 30a, the second layer 30b and the substrate 10, wherein the first initiation layer is a high refractive index layer and the second initiation layer is a low refractive index layer, the optical thickness of both the first initiation layer and the second initiation layer is less than 0.25λ, and the first initiation layer is closer to the substrate 10 or the semiconductor stack 20 than the second initiation layer.

[0091] For ease of explanation, the following description uses a first layer 30a as a high-refractive-index layer, such as TiO2, and a second layer 30b as a low-refractive-index layer, such as SiO2, as an example, but this is not intended to limit the scope of the invention. The optical field adjustment layer 30 comprises a multi-region film stack, each region comprising multiple first layers 30a and multiple second layers 30b. Each of the multiple first layers 30a comprises a first optical thickness, and each of the multiple second layers 30b comprises a second optical thickness. The multiple first optical thicknesses are variable, and / or the multiple second optical thicknesses are variable. The variation trend of the multiple first optical thicknesses is either thinning first and then thickening, or thickening first and then thinning. The variation trend of the multiple second optical thicknesses is either thinning first and then thickening, or thickening first and then thinning. Alternatively, when the optical thickness of one of the multiple first layers 30a and the multiple second layers 30b varies, the optical thickness of the other is substantially the same. The optical thickness difference between two adjacent first and second layers in each region of the film stack is greater than 0.025λ, preferably greater than 0.05λ, and more preferably greater than 0.1λ. The optical thickness is the product of the physical thickness and the refractive index (n) of the material layer. The following will describe this in detail according to different embodiments.

[0092] In one embodiment of the invention, the light field adjustment layer 30 includes a first region film stack and a second region film stack in the thickness direction, the first region film stack being closer to the substrate 10 or the semiconductor stack 20 than the second region film stack. A plurality of first layers 30a and a plurality of second layers 30b located in the first region are alternately stacked on top of each other, and a plurality of first layers 30a and a plurality of second layers 30b located in the second region are also alternately stacked on top of each other. The plurality of first layers 30a of the light field adjustment layer 30 have a first optical thickness less than 0.25λ, and the plurality of second layers 30b of the light field adjustment layer 30 have a second optical thickness greater than or approximately equal to 0.25λ. Figure 1 , Figure 2B and Figures 5A-5B As shown, when the peak wavelength of the light L generated by the active layer 23 is λ, the multiple first layers 30a of the optical field adjustment layer 30 each have a first optical thickness T1 less than 0.25λ but greater than 0.15λ. Figure 5A As shown, the plurality of second layers 30b of the light field adjustment layer 30 have a second optical thickness T2 greater than 0.25λ but less than 0.35λ. Or as Figure 5B As shown, each of the multiple second layers 30b has a second optical thickness T2 between 0.25λ and -0.025λ. Under the conditions described above, as Figures 5A-5B As shown, the first optical thickness of the plurality of first layers 30a can be thinned and then thickened, and / or the second optical thickness of the plurality of second layers 30b can be thinned and then thickened; or the first optical thickness of the plurality of first layers 30a can be thinned and then thickened, and / or the second optical thickness of the plurality of second layers 30b can be thickened and then thinned. In one embodiment, the first optical thickness of the plurality of first layers 30a can be thickened and then thinned (not shown), and / or the second optical thickness of the plurality of second layers 30b can be thinned and then thickened, or thickened and then thinned (not shown). In one embodiment, the first optical thickness of the plurality of first layers 30a can be less than 0.25λ but greater than 0.15λ, and maintain a thickness difference within 10% (not shown), and / or the second optical thickness of the plurality of second layers 30b can be greater than 0.25λ but less than 0.35λ, and maintain a thickness difference within 10% (not shown).

[0093] The first optical thickness difference between the plurality of first layers 30a in the first region membrane stack can be less than or greater than the first optical thickness difference between the plurality of first layers 30a in the second region membrane stack, and / or the second optical thickness difference between the plurality of second layers 30b in the first region membrane stack can be less than or greater than the second optical thickness difference between the plurality of second layers 30b in the second region membrane stack. The first optical thickness difference is the difference between the maximum and minimum values ​​of the first optical thickness. The second optical thickness difference is the difference between the maximum and minimum values ​​of the second optical thickness. In this embodiment, the first optical thickness difference is between 0.025λ and 0.1λ. When the second optical thickness T2 is greater than 0.25λ, the second optical thickness difference is between 0.025λ and 0.1λ. When the second optical thickness T2 is approximately equal to 0.25λ, the second optical thickness difference is less than 0.025λ.

[0094] In another embodiment of the invention, the first layer 30a of the light field adjustment layer 30 includes a first optical thickness approximately equal to 0.25λ, and the second layer 30b of the light field adjustment layer 30 includes a second optical thickness less than or greater than 0.25λ. Figure 1 , Figure 2B and Figures 6A-6B As shown, when the peak wavelength of the light L generated by the active layer 23 is λ, the first layer 30a of the light field adjustment layer 30 has a first optical thickness T1 between 0.25λ + / - 0.025λ. Figure 6A As shown, the second layer 30b has a second optical thickness T2 that is less than 0.25λ but greater than 0.15λ. (As...) Figure 6B As shown, the second layer 30b has a second optical thickness T2 greater than 0.25λ but less than 0.35λ. Under the conditions described above, the second optical thickness of the plurality of second layers 30b can first become thinner and then thicker, first become thicker and then thinner (not shown), or maintain a thickness difference within 10% (not shown), while the first optical thickness of the plurality of first layers 30a is substantially the same. The difference in second optical thickness between the plurality of second layers 30b located in the first region can be less than or greater than the difference in second optical thickness between the plurality of second layers 30b in the second region. In this embodiment, when the second optical thickness T2 is less than 0.25λ, the difference in second optical thickness is between 0.025λ and 0.1λ. When the second optical thickness T2 is greater than 0.25λ, the difference in second optical thickness is between 0.025λ and 0.1λ.

[0095] In another embodiment of the invention, the first layer 30a of the light field adjustment layer 30 includes a first optical thickness greater than 0.25λ, and the second layer 30b of the light field adjustment layer 30 includes a second optical thickness less than or approximately equal to 0.25λ. Figure 1 , Figure 2B and Figures 7A-7BAs shown, when the peak wavelength of the light L generated by the active layer 23 is λ, the first layer 30a of the light field adjustment layer 30 has a first optical thickness T1 greater than 0.25λ but less than 0.35λ. Figure 7A As shown, the second layer 30b has a second optical thickness T2 less than 0.25λ but greater than 0.15λ, or as... Figure 7B As shown, the second optical thickness T2 is between 0.25λ and -0.025λ. Under the above conditions, the first optical thickness of the plurality of first layers 30a can be thinned and then thickened, and / or the second optical thickness of the plurality of second layers 30b can be thinned and then thickened; or the first optical thickness of the plurality of first layers 30a can be thinned and then thickened, and / or the second optical thickness of the plurality of second layers 30b can be thickened and then thinned. In one embodiment, the first optical thickness of the plurality of first layers 30a can be thickened and then thinned, and / or the second optical thickness of the plurality of second layers 30b can be thinned and then thickened, or thickened and then thinned. In one embodiment, the first optical thickness of the plurality of first layers 30a can be greater than 0.25λ but less than 0.35λ, and maintain a thickness difference within 10% (not shown), and / or the second optical thickness of the plurality of second layers 30b can be less than 0.25λ but greater than 0.15λ, and maintain a thickness difference within 10% (not shown). The first optical thickness difference among the plurality of first layers 30a in the first region membrane stack can be less than or greater than the first optical thickness difference among the plurality of first layers 30a in the second region membrane stack, and / or the second optical thickness difference among the plurality of second layers 30b in the first region membrane stack can be less than or greater than the second optical thickness difference among the plurality of second layers 30b in the second region membrane stack. In this embodiment, the first optical thickness difference is between 0.025λ and 0.1λ. When the second optical thickness T2 is less than 0.25λ, the second optical thickness difference is between 0.025λ and 0.1λ. When the second optical thickness T2 is approximately equal to 0.25λ, the second optical thickness difference is less than 0.025λ.

[0096] In another embodiment of the invention, such as Figure 1 , Figure 2B and Figure 8As shown, when the peak wavelength of the light L generated by the active layer 23 is λ, the first layer 30a of the light field adjustment layer 30 has a first optical thickness less than 0.25λ, more preferably less than 0.2λ, but greater than 0.05λ. The second layer 30b of the light field adjustment layer 30 has a second optical thickness greater than or approximately equal to 0.25λ, but less than 0.4λ. Under the above conditions, the ratio of the second optical thickness of the plurality of second layers 30b to the first optical thickness of the plurality of first layers 30a is greater than 2.5. In this embodiment, the difference in first optical thickness is greater than 0.025λ but less than 0.1λ, and the difference in second optical thickness is greater than 0.005λ but less than 0.25λ. The difference in second optical thickness of the plurality of second layers 30b is greater than the first optical thickness of the plurality of first layers 30a. In this embodiment, the light field adjustment layer 30 comprises a single-region film stack, and the optical thickness is the product of the physical thickness and the refractive index (n) of the material layer. The first optical thickness difference is the difference between the maximum and minimum values ​​of the first optical thickness. The second optical thickness difference is the difference between the maximum and minimum values ​​of the second optical thickness.

[0097] Figure 2C This is a schematic diagram of the structure of the light field adjustment layer 30 according to another embodiment of the present invention. Figure 1 and Figure 2C As shown, the first layer 30a of the light field adjustment layer 30 includes a first optical thickness between 0.25 + / - 0.025λ, and the second layer 30b includes a second optical thickness between 0.25 + / - 0.025λ.

[0098] The optical field adjustment layer 30 includes a first region film stack and a second region film stack in the thickness direction, with the first region film stack being closer to the substrate 10 or the semiconductor stack 20 than the second region film stack. A plurality of first layers 30a and a plurality of second layers 30b located in the first region are alternately stacked on top of each other, and a plurality of first layers 30a and a plurality of second layers 30b located in the second region are also alternately stacked on top of each other. A first optical thickness difference between the plurality of first layers 30a in the first region film stack is approximately equal to a first optical thickness difference between the plurality of first layers 30a in the second region film stack, and / or a second optical thickness difference between the plurality of second layers 30b in the first region film stack is approximately equal to a second optical thickness difference between the plurality of second layers 30b in the second region film stack. In this embodiment, the first optical thickness difference is less than 0.025λ, and / or the second optical thickness difference is less than 0.025λ.

[0099] In this embodiment, the light field adjustment layer 30 includes a spatial layer 30c located between two adjacent first layers 30a or between two adjacent second layers 30b. The spatial layer 30c includes an optical thickness that is an even multiple of 0.25+ / -0.025λ, such as 0.5+ / -0.05λ or 1+ / -0.1λ.

[0100] In one embodiment of the invention, the first layer 30a of the light field adjustment layer 30 is a high refractive index layer, such as TiO2. x The optical field adjustment layer 30 consists of materials such as HfO2, ZnO, La2O3, CeO2, ZrO2, ZnSe, Si3N4, Nb2O5, or Ta2O5, and the second layer 30b is a low-refractive-index layer, such as SiO2, LaF3, MgF2, NaF, Na3AlF6, CaF2, or AlF3. If the space layer 30c is located between two adjacent first layers 30a, it contains SiO2, LaF3, MgF2, NaF, Na3AlF6, CaF2, or AlF3. If the space layer 30c is located between two adjacent second layers 30b, it contains TiO2. x , HfO2, ZnO, La2O3, CeO2, ZrO2, ZnSe, Si3N4, Nb2O5 or Ta2O5.

[0101] Electron beam evaporation, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or atomic vapor deposition are used to form the light field adjustment layer 30 to stably control the thickness of each layer of the Bragg mirror (DBR) structure.

[0102] In the field of displays, secondary optical elements are typically used to change the light source from a Lambertian beam pattern to a batwing beam pattern to achieve higher light uniformity. This is even more important for future direct-light displays, primarily based on Micro LEDs. Due to the high directivity of LEDs, additional diffusers or secondary optical elements are required for direct-light displays. This invention achieves a better uniform light pattern design through the design of a DBR and control of the light emission angle, thereby saving the cost of diffusers and secondary optical elements and reducing thickness. This makes the display cheaper and thinner, and various different light patterns can be achieved through this technology.

[0103] Figure 9 This is a schematic diagram of a light-emitting device 100 according to an embodiment of the present invention. Figure 9As shown, the light-emitting device 100 includes a circuit board 1001 and a light-emitting element 1 disposed on the circuit board 1001. The circuit board 1001 includes a first external electrode 1002a and a second external electrode 1002b. The first electrode 61 and the second electrode 62 of the light-emitting element 1 can be connected to the first external electrode 1002a and the second external electrode 1002b respectively through a first solder joint 1004a and a second solder joint 1004b.

[0104] The circuit board 1001 includes an insulating resin board, a ceramic board, or a metal board, such as a printed circuit board (PCB), a metal core printed circuit board (MOPCB), a metal printed circuit board (MPCB), or a flexible printed circuit board (FPCB).

[0105] In this embodiment, the first surface 101 of the substrate 10 is the main light emitting surface, and the light field adjustment layer 30 is disposed on the first surface 101 of the substrate 10.

[0106] Figure 10 This is a schematic diagram of a backlight module 7 according to an embodiment of the present invention. The backlight module 7 includes a first frame 201; a liquid crystal display screen 202; a brightness enhancement film 300; an optical module 400; a light-emitting module assembly 500; and a second frame 700, wherein the light-emitting module assembly 500 includes any one of the above-described light-emitting elements 1 or light-emitting devices 100, and is arranged in the light-emitting module assembly 500 in an edge-type or direct-type light-emitting manner. In another embodiment of the invention, the backlight module 7 further includes a wavelength conversion structure 600 located on the light-emitting module assembly 500.

[0107] Figure 11 This is a schematic diagram of a display 8 according to an embodiment of the present invention. The display 8 includes an LED light-emitting panel 1000; a current source (not shown); and a bracket 2000 to support the LED light-emitting panel 1000. The LED light-emitting panel 1000 includes a plurality of light-emitting elements 1 or light-emitting devices 100 as described above. The LED light-emitting panel 1000 includes a plurality of pixel units, each pixel unit including a plurality of light-emitting elements or light-emitting devices emitting different colors, for example, each pixel unit includes three light-emitting elements emitting red, green, and blue light respectively.

[0108] The embodiments listed in this invention are merely illustrative and not intended to limit the scope of the invention. Any obvious modifications or alterations made to this invention by any person do not depart from the spirit and scope of the invention.

Claims

1. A light-emitting element, comprising: substrate; A semiconductor stack, capable of emitting light with a peak wavelength λ, is located on the substrate; and An optical field adjustment layer is located on the substrate or the semiconductor stack, wherein the optical field adjustment layer comprises a plurality of first layers and a plurality of second layers, which are alternately stacked on top of each other, each of the plurality of first layers having a first optical thickness, and each of the plurality of second layers having a second optical thickness. The first optical thickness and the second optical thickness conform to: The first optical thickness of two adjacent elements in the plurality of first layers is less than 0.25λ, the second optical thickness of two adjacent elements in the plurality of second layers is greater than or equal to 0.25λ, one of the two adjacent elements in the plurality of first layers is located between the two adjacent elements in the plurality of second layers, and the refractive index of the two adjacent elements in the plurality of first layers is greater than the refractive index of the two adjacent elements in the plurality of second layers.

2. The light-emitting element as claimed in claim 1, wherein the first optical thicknesses of the plurality of first layers are first thinned and then thickened.

3. The light-emitting element as claimed in claim 1, wherein the first optical thickness of the plurality of first layers is first thickened and then thinned.

4. The light-emitting element as claimed in any one of claims 2 or 3, wherein the second optical thicknesses of the plurality of second layers are first thinned and then thickened.

5. The light-emitting element as claimed in any one of claims 2 or 3, wherein the second optical thickness of the plurality of second layers is first thickened and then thinned.

6. The light-emitting element of claim 1, wherein the light field adjustment layer comprises a first region film stack and a second region film stack, the first region film stack being closer to the substrate than the second region film stack, a portion of the plurality of first layers being located in the first region film stack and another portion of the plurality of first layers being located in the second region film stack, and a first optical thickness difference between two adjacent first layers located in the first region film stack being greater than a first optical thickness difference between two adjacent first layers located in the second region film stack.

7. The light-emitting element of claim 1, wherein the light field adjustment layer comprises a first region film stack and a second region film stack, the first region film stack being closer to the substrate than the second region film stack, a portion of the plurality of first layers being located in the first region film stack and another portion of the plurality of first layers being located in the second region film stack, and the first optical thickness difference between two adjacent first layers located in the first region film stack being smaller than the first optical thickness difference between two adjacent first layers located in the second region film stack.

8. The light-emitting element as claimed in any one of claims 6 or 7, wherein a portion of the plurality of second layers is located in the first region film stack and another portion of the plurality of second layers is located in the second region film stack, the optical thickness difference between one of two adjacent first layers in the first region film stack and one of the plurality of second layers in the first region film stack is greater than 0.05λ, and the optical thickness difference between one of two adjacent first layers in the second region film stack and one of the plurality of second layers in the second region film stack is greater than 0.05λ.

9. The light-emitting element as claimed in any one of claims 6 or 7, wherein a portion of the plurality of second layers is located in the first region film stack and another portion of the plurality of second layers is located in the second region film stack, the optical thickness difference between one of two adjacent first layers located in the first region film stack and one of the plurality of second layers located in the first region film stack is greater than 0.1λ, and the optical thickness difference between one of two adjacent first layers located in the second region film stack and one of the plurality of second layers located in the second region film stack is greater than 0.1λ.

10. The light-emitting element of claim 1, wherein the sum of the first optical thicknesses of the plurality of first layers and the second optical thicknesses of the plurality of second layers is 1 μm to 3 μm.

11. The light-emitting element of claim 1, wherein the plurality of first layers and the plurality of second layers of the light field adjustment layer, the layer closest to the substrate, comprises TiO. x The optical field adjustment layer contains HfO2, ZnO, La2O3, CeO2, ZrO2, ZnSe, Si3N4, Nb2O5, or Ta2O5, and the layer furthest from the substrate among the plurality of first layers and the plurality of second layers contains SiO2, LaF3, MgF2, NaF, Na3AlF6, CaF2, or AlF3.

12. The light-emitting element of claim 1, wherein the plurality of first layers comprises TiO2. x The plurality of second layers contain HfO2, ZnO, La2O3, CeO2, ZrO2, ZnSe, Si3N4, Nb2O5 or Ta2O5, and the plurality of second layers contain SiO2, LaF3, MgF2, NaF, Na3AlF6, CaF2 or AlF3.

13. The light-emitting element as claimed in claim 1, wherein the light-emitting element has a batwing-shaped light distribution.

14. The light-emitting element of claim 1, wherein the light field adjustment layer comprises a first initiation layer and a second initiation layer located between the plurality of first layers, the plurality of second layers and the substrate.

15. The light-emitting element of claim 14, wherein the first initiation layer comprises an optical thickness of less than 0.25λ.

16. The light-emitting element of claim 14, wherein the second initiation layer comprises an optical thickness of less than 0.25λ.

17. The light-emitting element as claimed in claim 15 or 16, wherein the first initiation layer is closer to the substrate than the second initiation layer.

18. The light-emitting element of claim 1, wherein the substrate includes a first surface and a second surface, the light field adjustment layer is disposed on the first surface of the substrate, and the semiconductor stack is disposed on the second surface of the substrate.

19. The light-emitting element as claimed in claim 18, wherein the first surface of the substrate is the main light-emitting surface of the light-emitting element.

20. The light-emitting element of claim 18, comprising a reflective layer disposed on the semiconductor stack, the reflective layer comprising a distributed Bragg reflector (DBR) structure formed by alternating stacking of two or more insulating materials with different refractive indices.

21. The light-emitting element of claim 20, wherein the reflective layer comprises aluminum (Al), silver (Ag), rhodium (Rh), or platinum (Pt).

22. The light-emitting element as claimed in claim 20 or 21, comprising a first electrode and a second electrode disposed on the semiconductor stack, and an insulating layer located on the first electrode and the second electrode, wherein the insulating layer is formed by alternating stacking of two or more materials with different refractive indices to form a reflective structure comprising a distributed Bragg mirror (DBR).

23. The light-emitting element of claim 1, comprising a protective layer located on the semiconductor stack, wherein the protective layer comprises a distributed Bragg reflector (DBR) structure having a first region, a second region and a third region, the first region being closest to the semiconductor stack, the second region being farther away from the semiconductor stack, the third region being between the first region and the second region, the first region, the second region and the third region being formed by alternating stacking of a third layer and a fourth layer made of two different materials, and the protective layer having a thickness of 2.5 μm to 3.5 μm.

24. The light-emitting element of claim 23, wherein the third optical thickness of the third layer located in the third region is less than the third optical thickness of the third layer located in the first region.

25. The light-emitting element of claim 24, wherein the third optical thickness of the third layer in the third region is greater than the third optical thickness of the third layer in the second region.

26. The light-emitting element of claim 23, wherein the third optical thickness of the third layer located in the first region is greater than 0.25λ.

27. The light-emitting element of claim 23, wherein the third optical thickness of the third layer located in the third region is equal to 0.25λ.

28. The light-emitting element of claim 25, wherein the third optical thickness of the third layer located in the second region is less than 0.25λ.

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