TWI905195B - Light-emitting device - Google Patents

Abstract

A light-emitting device includes a substrate; a semiconductor stack capable of emitting a light having a peak wavelength λ, located on the substrate; and a light field adjustment layer located on the substrate or the semiconductor stack, wherein the light field adjustment layer includes 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 includes a first optical thickness, and each of the plurality of second layers includes a second optical thickness.

Description

Light-emitting element

This invention relates to a light-emitting element, and more particularly to a light-emitting element comprising a light field adjustment layer.

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 characteristics, such as stable emission wavelength. Therefore, LEDs are widely used in household appliances, equipment indicator lights, and optoelectronic products.

According to one 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 stack, 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.

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

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

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

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 conditioning layer located on the substrate or the semiconductor layer, wherein the light field conditioning layer comprises a plurality of first layers, a plurality of second layers, and a spatial layer located between two adjacent plurality of first layers or between two adjacent plurality of second layers, wherein the spatial layer comprises an optical thickness that is an even multiple of 0.25 +/- 0.025 λ.

1: Light-emitting element

10:Substrate

20: Semiconductor Stack

21: First Semiconductor Layer

22: Second Semiconductor Layer

23: Active layer

30: Light Field Adjustment Layer

30a: First layer

30b: Second layer

30c: Spatial Layer

40:Transparent conductive layer

41: Reflective layer

50: Protective Layer

51: The Insulation Layer

61: First Electrode

62: Second electrode

71: First electrode pad

72: Second electrode pad

100: Light-emitting device

101: First Page

102: Second Page

511: First Insulation Layer Opening

512: Second Insulation Layer Opening

1001:Circuit board

1002a: First external electrode

1002b: Second external electrode

1004a: First Welding Section

1004b: Second Welding Section

θi: Angle of incidence

θj: Angle of departure

θ1: First region

θ2: Second region

L:Light

Figure 1 is a side view of one of the light-emitting elements 1 disclosed in an embodiment of the present invention.

Figure 2 is the emission spectrum of a light-emitting element 1 according to one embodiment of the present invention.

Figure 2A is a partial enlarged view of area A in Figure 1 according to one embodiment of the present invention.

Figure 2B is a partial enlarged view of area A in Figure 1 according to another embodiment of the present invention.

Figure 3 is a schematic diagram illustrating the propagation of light according to an embodiment of the present invention.

Figure 3A is a schematic diagram illustrating the propagation of light according to an embodiment of the present invention.

Figure 3B is a light field distribution diagram of the light-emitting element 1 disclosed in an embodiment of the present invention.

Figure 4 shows the light field distribution of a learned light-emitting element.

Figures 5A and 5B show the optical thickness variation of the light field adjustment layer 30 as disclosed in an embodiment of the present invention.

Figures 6A and 6B show the optical thickness variation of the light field adjustment layer 30 as disclosed in an embodiment of the present invention.

Figures 7A and 7B show the optical thickness variation of the light field adjustment layer 30 as disclosed in an embodiment of the present invention.

Figure 8 is a graph showing the optical thickness variation of the light field adjustment layer 30 as disclosed in an embodiment of the present invention.

Figure 9 is a schematic diagram of a light-emitting device 100 according to an embodiment of the present invention.

Figure 10 is a schematic diagram of a backlight module 7 according to an embodiment of the present invention.

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

To provide a more detailed and complete description of this invention, please refer to the following embodiments and related figures. However, the embodiments shown below are for illustrating the light-emitting element of this invention and are not intended to limit the invention to these embodiments. Furthermore, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the constituent parts described in the embodiments are not limited to these aspects and are merely illustrative. The sizes or positional relationships of the components shown in the figures may be exaggerated for clarity. Moreover, in the following description, to appropriately omit detailed descriptions, the same name and symbols are used to represent components of the same nature.

Figure 1 is a side view of a light-emitting element 1 disclosed in one embodiment of the present invention. Figure 2 is an emission spectrum of the light-emitting element 1 according to one embodiment of the present invention. Figure 2A is a partial enlarged view of region A in Figure 1 according to one embodiment of the present invention. Figure 2B is a partial enlarged view of region A in Figure 1 according to another embodiment of the present invention.

As shown in Figure 1, 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.

The substrate 10 may be a growth substrate for epitaxial growth of semiconductor stacks 20. The substrate 10 includes gallium arsenide (GaAs) wafers for epitaxial growth of aluminum gallium indium phosphide (AlGaInP), or sapphire ( _Al₂O₃ ) wafers, gallium nitride ( _GaN ) wafers, silicon carbide (SiC) wafers, or aluminum gallium nitride (AlGaN) wafers for growth of gallium nitride (GaN), indium gallium nitride (InGaN), or aluminum gallium nitride (AlGaN).

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, selectively reflecting and transmitting light emitted from the semiconductor stack 20 with a peak wavelength λ, causing the transmittance of the light to vary with the incident angle, thereby adjusting the light field distribution of the light-emitting element 1. As shown in Figure 2, the semiconductor stack 20 of the light-emitting element 1 emits light ranging from 430 nm to 470 nm, where the peak wavelength λ is the wavelength of the maximum relative light intensity, for example, 450 nm.

The substrate 10 is connected to the semiconductor stack 20 via a second surface 102. The second surface 102 can be a roughened surface. A 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.

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 using organometallic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydrogenation vapor deposition (HVPE), physical vapor deposition (PVD), or ion electroplating. The physical vapor deposition method includes sputtering or evaporation.

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 the light emitted by the light-emitting element 1 is 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-xy) N, Al _x Ga _(1-x) As, or Al _x In _y Ga _(1-xy) P, where 0≦x, y≦1; (x+y)≦1. When the semiconductor stack 20 is made of AlGaAs or AlInGaP series materials, it emits red light with wavelengths between 610nm and 650nm, or green light with wavelengths between 530nm and 570nm. When the semiconductor stack 20 is made of InGaN series materials, it emits blue or deep blue light with wavelengths between 400nm and 490nm, or green light with wavelengths between 490nm and 550nm. When the semiconductor stack 20 is made of AlGaN or AlInGaN series materials, it emits ultraviolet light with wavelengths between 250nm and 400nm.

The first semiconductor layer 21 and the second semiconductor layer 22 can be cladding layers with different conduction types, electrical properties, and polarities, or they can be doped with elements to provide electrons or holes. For example, the first semiconductor layer 21 is an n-type semiconductor and the second semiconductor layer 22 is 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 an electric 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 (DDH), 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 or a structure containing multiple layers.

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 structure containing multiple layers. 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 can be used to reactively form aluminum nitride in a nitrogen source environment.

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).

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, as shown in Figure 1, the light field adjustment layer 30 is disposed on the first surface 101 of the substrate 10. When the light-emitting element 1 is a lateral 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 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 emitting surface.

When the light-emitting element 1 is a flip chip structure, as shown in Figure 1, in order 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 make the reflected light 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 41, 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 prevent oxidation of the surface of the metal reflective layer 41 and thus deterioration of its reflectivity, a barrier layer (not shown) can be formed on the metal reflective layer 41 to cover its upper and side surfaces. The barrier layer (not shown) is made of metallic materials, such as titanium (Ti), tungsten (W), aluminum (Al), indium (In), tin (Sn), nickel (Ni), chromium (Cr), platinum (Pt), or alloys thereof. The barrier layer can be a one- or multi-layer structure, such as a titanium (Ti)/aluminum (Al) structure and/or a nickel-titanium alloy (NiTi)/titanium-tungsten alloy (TiW). When the reflective layer 41 is an insulating reflective structure 41, it comprises a distributed Bragg reflector (DBR) structure formed by alternating layers of two or more insulating materials with different refractive indices. In one embodiment of the invention, when the reflective layer 41 is an insulating reflective structure 41, 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 structure 41. In one embodiment of the invention, the second electrode 62 includes a reflective metallic material, which can be used in conjunction with the insulating reflective structure 41 to form an omnidirectional reflector.

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

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 via an opening 512 in the second insulation layer.

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 be composed 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 external power supply 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.

The protective layer 50 and the insulating layer 51 are made of non-conductive materials. Non-conductive materials include organic materials, inorganic materials, or dielectric materials. Organic materials include Su8, benzocyclobutene (BCB), perfluorocyclobutane (PFCB), epoxy resin, acrylic resin, cycloolefin polymer (COC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyetherimide, or fluorocarbon polymer. Inorganic materials include silicone or glass. The dielectric material includes aluminum oxide ( _Al₂O₃ ), silicon nitride ( _SiN ), silicon oxide ( _SiOₓ ), _silicon oxynitride ( _SiOₓNy ), titanium oxide ( _TiOₓ ), or magnesium fluoride ( _MgFₓ ). 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 multi-layer structure by combining the above materials, for example, by alternately stacking two or more materials with different refractive indices to form a reflective structure including a distributed Bragg reflector (DBR). The protective layer 50 and/or the insulating layer 51 preferably have a thickness of 0.5μm to 4μm, more preferably a thickness of 2.5μm to 3.5μm, and even more preferably a thickness of 2.7μm to 3.3μm.

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

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. Both the first and second regions have multiple film layers. The multiple film layers of the first and second regions are formed by alternating stacks of film layers composed 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 composed of two materials, respectively. The third layer has a third refractive index (low refractive index), such as _SiO2 layer (n: about 1.47), and the fourth layer has a fourth refractive index (high refractive index), such as _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, 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 region 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. The multiple film layers in the third and fourth regions 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 a third layer and a fourth layer composed of two materials. The material of the third layer has a third refractive index (low refractive index), such as _SiO2 layer (n: about 1.47), and the material of the fourth layer has a fourth refractive index (high refractive index), such as _TiO2 layer (n: about 2.41). In one embodiment, the third and fourth layers of the third region each include a third optical thickness and a fourth optical thickness; the third and fourth layers of the fourth region each include a third optical thickness and a fourth optical thickness. The third and fourth optical thicknesses of regions three and four are respectively less than and greater than the third and fourth optical thicknesses of regions one and two, respectively, and the third and fourth optical thicknesses of regions two and three are greater than or equal to the third and fourth optical thicknesses of regions four. In one embodiment, the third and fourth optical thicknesses of regions three and four are respectively greater than 0.25λ, and the third and fourth optical thicknesses of regions four and four are respectively greater than 0.25λ. In one embodiment, the third and fourth optical thicknesses of regions three and four are respectively greater than 0.25λ, and the third and fourth optical thicknesses of regions four and four are respectively less than 0.25λ. In one embodiment, the third and fourth optical thicknesses of regions three and four are respectively less than 0.25λ, and the third and fourth optical thicknesses of regions four and four 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.

The optical thickness difference between two adjacent third and fourth material layers located 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.

A light field adjustment layer 30 is disposed on the main emitting surface of the light-emitting element 1, adjusting the light field distribution of the light-emitting element 1 by reflecting light 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 reflector (DBR) structure, selectively reflecting light of specific wavelengths and causing the light transmittance to vary according to its incident angle.

The main emitting surface of the light-emitting element 1, depending on its structure, 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, as shown in Figure 1, 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 in the figure).

Taking the light-emitting element 1 as a flip chip structure as an example, according to Snell's law, as shown in Figure 3, due to the changes in the refractive index of the materials encountered by 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 enters the light field adjustment layer 30.

Specifically, as shown in Figures 3A and 3B, when light L is incident on the light field adjustment layer 30 at an angle of incidence less than θi and exits through it, it exhibits a first light intensity in the first region θ1. When light L is incident on the light field adjustment layer 30 at an angle of incidence greater than θi and exits through it, it exhibits 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 angle of incidence less than θi, thus the light-emitting element 1 has a batwing-shaped light field distribution.

As shown in Figure 3B, the transmittance of light L is highest near an emission angle of 60 to 70 degrees, and maintains a generally high transmittance within an angle range of 30 to 80 degrees.

Figure 4 shows the light field distribution of a conventional light-emitting element without the light field adjustment layer 30. Compared to Figure 4, Figure 3B shows that the light intensity of ray L decreases significantly between 0 and 30 degrees, while the light intensity relatively increases between 30 and 90 degrees.

By replacing the lens optical structure with 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.

As shown in Figures 2A and 2B, 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. As shown in Figures 3A and 3B, 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 the specific incident angle θi, thereby adjusting the batwing-shaped light field distribution. 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 emitted from the light field adjustment layer 30, when 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.

In this embodiment, the transmittance of light L at each incident angle is adjusted by selecting the refractive index, thicknesses _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 thereon.

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 a plurality of first layers 30a and a plurality of second layers 30b, can be designed to be 0.5μm to 5μm, preferably 1μm to 3μm, and more preferably 1.5μm to 2μm.

One of the first layer 30a and the second layer 30b of the optical field adjustment layer 30 is a high refractive index layer, such as _TiO₂ , _HfO₂ , _ZnO , _La₂O₃ , _CeO₂ , _ZrO₂ , ZnSe, _Si₃N₄ , _{Nb₂O₅ or Ta₂O₅} , and the other 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 .

In one embodiment of the invention, the first and/or last layer of the optical field adjustment layer ₃₀ comprises _TiO₂x , _HfO₂ , ZnO, _La₂O₃ , _CeO₂ , _ZrO₂ , _ZnSe , _Si₃N₄ , _{Nb₂O₅ or Ta₂O₅ .}

In another embodiment of the invention, the first and/or last layer of _the optical field adjustment layer 30 comprises _SiO2 , _LaF3 , _MgF2 , NaF, _Na3AlF6 , _CaF2 or _AlF3 .

In another embodiment of the invention, the optical 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. 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 and second initiation layers 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.

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 disclosure of the present invention. The optical field adjustment layer 30 comprises a plurality of regions of film stacks, each region of film stacks comprising a plurality of first layers 30a and a plurality of second layers 30b. The plurality of first layers 30a each comprises a first optical thickness, and the plurality of second layers 30b each comprises a second optical thickness. The plurality of first optical thicknesses are variable, and/or the plurality of second optical thicknesses are variable. The variation trend of the plurality of first optical thicknesses is either first thinning and then thickening, or first thickening and then thinning. The variation trend of the plurality of second optical thicknesses is either first thinning and then thickening, or first thickening and then thinning. Alternatively, when the plurality of optical thicknesses of one of the plurality of first layers 30a and the plurality of second layers 30b change, the plurality of optical thicknesses of the other are substantially the same. The difference in optical thickness between two adjacent first and second layers located 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. This will be explained in detail below according to different embodiments.

In one embodiment of the invention, the optical 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 alternately stacked on top of each other. The plurality of first layers 30a of the optical field adjustment layer 30 includes a first optical thickness less than 0.25λ, and the plurality of second layers 30b of the optical field adjustment layer 30 includes a second optical thickness greater than or approximately equal to 0.25λ. As shown in Figures 1, 2A, and 5A-5B, when the peak wavelength of the light L generated by the active layer 23 is λ, each of the plurality of first layers 30a of the light field adjustment layer 30 has a first optical thickness _T1 less than 0.25λ but greater than 0.15λ. As shown in Figure 5A, each of the plurality of second layers 30b of the light field adjustment layer 30 has a second optical thickness _T2 greater than 0.25λ but less than 0.35λ. Or, as shown in Figure 5B, each of the plurality of second layers 30b has a second optical thickness _T2 between 0.25λ and -0.025λ. Under the conditions described above, as shown in Figures 5A-5B, the first optical thickness of a plurality of first layers 30a can be thinned and then thickened, and/or the second optical thickness of a plurality of second layers 30b can be thinned and then thickened; or the first optical thickness of a plurality of first layers 30a can be thinned and then thickened, and/or the second optical thickness of a plurality of second layers 30b can be thickened and then thinned. In one embodiment, the first optical thickness of a plurality of first layers 30a can be thickened and then thinned (not shown), and/or the second optical thickness of a 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 a plurality of first layers 30a may be less than 0.25 λ but greater than 0.15 λ, and maintain a thickness difference within 10% (not shown in the figure), and/or the second optical thickness of a plurality of second layers 30b may be greater than 0.25 λ but less than 0.35 λ, and maintain a thickness difference within 10% (not shown in the figure).

The first optical thickness difference between a plurality of first layers 30a in the first region membrane stack may be less than or greater than the first optical thickness difference between a plurality of first layers 30a in the second region membrane stack, and/or the second optical thickness difference between a plurality of second layers 30b in the first region membrane stack may be less than or greater than the second optical thickness difference between a 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 difference in the second optical thickness is less than 0.025λ.

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. As shown in Figures 1, 2A, and 6A-6B, 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 and 0.025λ. As shown in Figure 6A, the second layer 30b has a second optical thickness _T2 less than 0.25λ but greater than 0.15λ. As shown in Figure 6B, 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, or first become thicker and then thinner (not shown in the figure), or maintain a thickness difference within 10% (not shown in the figure), 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 located 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.

In another embodiment of the invention, the first layer 30a of the light field adjustment layer 30 has a first optical thickness greater than 0.25λ, and the second layer 30b of the light field adjustment layer 30 has a second optical thickness less than or approximately equal to 0.25λ. As shown in Figures 1, 2A, and 7A-7B, 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. As shown in Figure 7A, the second layer 30b has a second optical thickness _T2 less than 0.25λ but greater than 0.15λ, or as shown in Figure 7B, the second optical thickness _T2 is between 0.25λ and -0.025λ. Under the conditions described above, the first optical thickness of a plurality of first layers 30a may first become thinner and then thicker, and/or the second optical thickness of a plurality of second layers 30b may first become thinner and then thicker; or the first optical thickness of a plurality of first layers 30a may first become thinner and then thicker, and/or the second optical thickness of a plurality of second layers 30b may first become thicker and then thinner. In one embodiment, the first optical thickness of a plurality of first layers 30a may first become thicker and then thinner, and/or the second optical thickness of a plurality of second layers 30b may first become thinner and then thicker, or thicker and then thinner. In one embodiment, the first optical thickness of a plurality of first layers 30a may be greater than 0.25λ but less than 0.35λ, and maintain a thickness difference within 10% (not shown in the figure), and/or the second optical thickness of a plurality of second layers 30b may be less than 0.25λ but greater than 0.15λ, and maintain a thickness difference within 10% (not shown in the figure). The first optical thickness difference of a plurality of first layers 30a in the first region of the membrane stack may be less than or greater than the first optical thickness difference between a plurality of first layers 30a in the second region of the membrane stack, and/or the second optical thickness difference of a plurality of second layers 30b in the first region of the membrane stack may be less than or greater than the second optical thickness difference between a plurality of second layers 30b in the second region of the 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.

In another embodiment of the invention, as shown in Figures 1, 2A, and 8, 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 first optical thickness difference is greater than 0.025λ but less than 0.1λ, and the second optical thickness difference is greater than 0.005λ but less than 0.25λ. The second optical thickness difference 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 optical 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.

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

The optical 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 is closer to the substrate 10 or 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 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.

In this embodiment, the optical field adjustment layer 30 includes a spatial layer 30c located between two adjacent plurality of first layers 30a or between two adjacent plurality of second layers 30b, wherein the spatial layer 30c includes an optical thickness that is an even multiple of 0.25 +/- 0.025 λ, for example, 0.5 +/- 0.05 λ or 1 +/- 0.1 λ.

In one embodiment of the invention, the first layer 30a of the optical field adjustment layer 30 is a high refractive index layer, such _{as TiO₂} , _HfO₂ , _ZnO , _La₂O₃ , _CeO₂ , _ZrO₂ , ZnSe, _Si₃N₄ , _Nb₂O₅ or _Ta₂O₅ , 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 . If the space layer 30c is located between two adjacent plurality of first layers 30a, the space layer 30c contains SiO ₂ , LaF ₃ , MgF ₂ , NaF, Na _{3AlF 6} , CaF ₂ , or AlF _3. If the space layer 30c is located between two adjacent plurality of second layers 30b, the space layer 30c contains TiO _x , HfO ₂ , ZnO, La _{2O 3} , CeO ₂ , ZrO ₂ , ZnSe, Si _{3N 4} , Nb _{2O 5} , or Ta _{2O 5} .

Electron beam evaporation, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or atomic vapor deposition are used to form the optical field conditioning layer 30 to stably control the thickness of each layer in the DBR structure.

In the field of displays, secondary optical elements are typically used to change the light source pattern from a Lambertian to a batwing-shaped light source to achieve higher light uniformity. This is even more important for future direct-light displays based on Micro LED. 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 DBR design and light emission angle control, saving on the cost of diffusers and secondary optical elements and reducing thickness. This allows for cheaper and thinner displays, and enables the realization of various different light patterns.

Figure 9 is a schematic diagram of a light-emitting device 100 according to an embodiment of the present invention. As shown in Figure 9, 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 via a first solder joint 1004a and a second solder joint 1004b.

Circuit board 1001 includes insulating resin boards, ceramic boards, or metal boards, such as printed circuit boards (PCBs), metal-core printed circuit boards (MOPCBs), metal printed circuit boards (MPCBs), or flexible printed circuit boards (FPCBs).

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.

Figure 10 is a schematic diagram of a backlight module 7 according to one 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. The light-emitting module assembly 500 includes a plurality of the aforementioned light-emitting elements 1 or light-emitting devices 100, arranged 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.

Figure 11 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 multiple 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.

The embodiments listed herein are for illustrative purposes only and are not intended to limit the scope of the invention. Any obvious modifications or alterations made to the invention by any person shall not depart from the spirit and scope of the invention.

1: Light-emitting element

10:Substrate

20: Semiconductor Stack

21: First Semiconductor Layer

22: Second Semiconductor Layer

23: Active layer

30: Light Field Adjustment Layer

40:Transparent conductive layer

41: Reflective layer

50: Protective Layer

51: The Insulation Layer

61: First Electrode

62: Second electrode

71: First electrode pad

72: Second electrode pad

101: First Page

102: Second Page

511: First Insulation Layer Opening

512: Second Insulation Layer Opening

Claims (10)

A light-emitting element includes: a substrate; a semiconductor stack capable of emitting light having a peak wavelength λ, disposed on the substrate; and a light field adjustment layer disposed on the substrate or the semiconductor stack, wherein the light field adjustment layer includes 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 having a first optical thickness, and each of the plurality of second layers having a second optical thickness, wherein the first optical thickness... The degree and the second optical thickness meet the following conditions: the first optical thickness of two adjacent plurality of first layers is less than 0.25λ, the second optical thickness of two adjacent plurality of second layers is greater than or approximately equal to 0.25λ, one of the two adjacent plurality of first layers is located between the two adjacent plurality of second layers, and the refractive index of the two adjacent plurality of first layers is greater than the refractive index of the two adjacent plurality of second layers. The light-emitting element as described in claim 1, wherein the first optical thickness of the plurality of adjacent first layers is first thinned and then thickened. The light-emitting element as described in claim 1, wherein the first optical thickness of the plurality of adjacent first layers first increases and then decreases. The light-emitting element as described in claim 2 or 3, wherein the second optical thickness of the plurality of adjacent second layers is first thinned and then thickened. The light-emitting element as described in claim 2 or 3, wherein the second optical thickness of the plurality of adjacent second layers first thickens and then thins. The light-emitting element as described in 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, and the first optical thickness difference between two adjacent plurality of first layers in the first region film stack being greater than or less than the first optical thickness difference between two adjacent plurality of first layers in the second region film stack. The light-emitting element as described in claim 1 or 6, wherein the light field adjustment layer includes a first starting layer and a second starting layer located between the two adjacent plurality of first layers and the substrate or between the adjacent plurality of second layers and the substrate, and the optical thickness of the first starting layer and/or the second starting layer is less than 0.25λ. The light-emitting element as described in claim 1, wherein the light-emitting element has a batwing-shaped light distribution. An emitting element includes: a substrate; a semiconductor stack capable of emitting light having a peak wavelength λ, disposed on the substrate; and a light field adjustment layer disposed on the substrate or the semiconductor stack, wherein the light field adjustment layer includes a plurality of first layers, a plurality of second layers, and a space layer disposed between two adjacent plurality of first layers or between two adjacent plurality of second layers, wherein the space layer includes an optical thickness that is an even multiple of 0.25 +/- 0.025λ. The light-emitting element as described in claim 9, wherein the optical thickness of the space layer is 0.5+/-0.05λ or 1+/-0.1λ.