Miniature light emitting diode array
By introducing a refractive index adjustment layer and a light adjustment structure into the micro-light emitting diode array, the problem of total reflection of the micro-light emitting diode light out interface is solved, and the light extraction efficiency is improved.
Patent Information
- Application Number
- CN202411404550.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2025-02-11
AI Technical Summary
Due to the high refractive index of the micro-light-emitting diode light-emitting interface material, light easily forms a total reflection in the light-emitting interface, reducing the light extraction efficiency.
A micro-light emitting diode array structure is adopted, including a micro-light emitting diode, an isolation structure, a compound semiconductor layer and a refractive index adjustment layer. The compound semiconductor layer covers the micro-light emitting diode and the isolation structure, the refractive index adjusting layer covers the compound semiconductor layer, and the refractive index of light is adjusted by the light adjustment structure such as a trench or a metal layer.
By reducing the refractive index difference between the light exit interface and the air, the total reflection phenomenon is reduced, the light extraction efficiency is improved, and the area of the effective light source area is increased.
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Figure CN119421584A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present application relate to a micro light emitting diode array. Background Art
[0002] A light emitting diode (LED) is a solid-state semiconductor device that can convert electrical energy into light energy and provides many advantages over other light sources, such as small size, high brightness, low power consumption, low heat generation, long service life, and environmental protection. It also has a variety of colors. LEDs can be used as light sources in many display systems, such as mobile phones, computers, televisions and other electronic products.
[0003] Micro LED refers to the miniaturization and matrix technology of light-emitting diodes. Specifically, micro LED refers to a high-density array of tiny-sized LED chips integrated on a display panel, in which each LED chip can be addressed and driven to light up individually. The pixel distance between two adjacent LED chips can be reduced from millimeters to micrometers, and the display effect can be improved.
[0004] Since the material of the light-emitting interface of the current micro-LED usually has a high refractive index, for example, for blue light with a wavelength of about 460nm, the refractive index of the GaN material of the light-emitting interface is as high as about 2.45, which is very different from the refractive index of air of about 1.00, so that the light from the light source is easily reflected at the light-emitting interface, thereby reducing the light extraction efficiency. Therefore, a structure that reduces the refractive index difference between the light-emitting interface and air is needed to solve the above problem. Summary of the invention
[0005] An embodiment of the present application provides a micro-light emitting diode array, including a plurality of micro-light emitting diodes, an isolation structure located between the micro-light emitting diodes, a compound semiconductor layer covering the micro-light emitting diodes and the isolation structure, wherein the compound semiconductor layer has a first refractive index, a refractive index adjustment layer covering the compound semiconductor layer, wherein the refractive index adjustment layer has a second refractive index that is less than the first refractive index, and a light adjustment structure that penetrates the refractive index adjustment layer and extends into the compound semiconductor layer.
[0006] In some embodiments, the second refractive index of the refractive index adjusting layer is greater than the third refractive index of the light adjusting structure.
[0007] In some embodiments, the refractive index adjustment layer includes ZrO 2 or TiO 2 A resin layer.
[0008] In some embodiments, the light-adjusting structure is a groove.
[0009] In some embodiments, the third refractive index of the light-modulating structure is smaller than the first refractive index of the compound semiconductor layer.
[0010] In some embodiments, the light regulating structure extends toward the isolation structure.
[0011] In some embodiments, the micro-LED array further includes an insulating layer located between the light-modulating structure and the compound semiconductor layer, wherein the light-modulating structure is a metal layer.
[0012] In some embodiments, the insulating layer extends between the compound semiconductor layer and the refractive index adjusting layer.
[0013] In some embodiments, the light regulating structure is a metal layer, and the light regulating structure has an air gap.
[0014] In some embodiments, the light regulating structure is a metal layer, and the light regulating structure does not have an air gap. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The technical solution of the present application is best understood from the following detailed description when read through the accompanying drawings. Note that various features are not drawn to scale according to standard practice in the industry. In fact, the size of various features may be arbitrarily increased or decreased for clarity of discussion.
[0016] Figure 1 Schematic diagram of a micro light emitting diode array according to some embodiments of the present application.
[0017] Figure 2 Schematic diagram of light extraction efficiency of a micro-LED array according to some embodiments of the present application.
[0018] Figure 3A Schematic diagram of a micro light emitting diode array according to some embodiments of the present application.
[0019] Figure 3B Schematic diagram of light extraction efficiency of a micro-LED array according to some embodiments of the present application.
[0020] Figure 4 Schematic diagram of the refractive index adjustment material of the micro light emitting diode array according to some embodiments of the present application.
[0021] Figure 5A Schematic diagram of the metal layer of a micro light emitting diode array according to some embodiments of the present application.
[0022] Figure 5B Schematic diagram of the metal layer of a micro light emitting diode array according to some embodiments of the present application.
[0023] Description of reference numerals:
[0024] 10: micro-LED array; 50: external environment; 60: groove; 100: micro-LED; 110: n-type semiconductor layer; 120: active layer; 130: p-type semiconductor layer; 140: transparent conductive layer; 150: contact layer; 160: soldering pad; 170: intermetallic dielectric layer; 200: isolation structure; 300: compound semiconductor layer; 400: refractive index adjustment layer; 505: light; 510: effective light source area; 511: ineffective light source area; 517: light output interface; 518: light output interface; 600: refractive index adjustment material; 700: metal layer; 710: insulating layer; α1: incident angle; α2: incident angle; α3: incident angle; α4: incident angle; α5: incident angle; α6: incident angle. DETAILED DESCRIPTION
[0025] The following disclosure provides many different embodiments or examples for implementing different features of the provided target. Specific examples of components and configurations are described below to simplify the present application. Of course, these are only examples and are not intended to be restrictive. For example, in the following description, the formation of a first feature above or on a second feature may include an embodiment in which the first and second features are directly contacted, and may also include an embodiment in which additional features may be formed between the first and second features so that the first and second features may not be in direct contact. In addition, in various examples, the present application may repeat reference numbers and / or letters. This repetition is for the purpose of simplicity and clarity, and does not itself define the relationship between the various embodiments and / or configurations discussed.
[0026] Additionally, for ease of description, spatially relative terms such as "beneath," "below," "lower," "above," and "upper," and the like, may be used herein to describe the relationship of one component or feature to another component or feature as illustrated in the figures. These spatially relative terms are intended to encompass different orientations of the components in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein likewise interpreted accordingly.
[0027] As used herein, "approximately," "about," "roughly," or "substantially" may generally mean within 20%, or within 10%, or within 5% of a given value or range. The numerical values given herein are approximate, meaning that if not explicitly stated, the term "approximately," "about," "roughly," or "substantially" may be inferred. However, those skilled in the art will recognize that the values or ranges listed throughout the description are merely examples and may be reduced or varied as integrated circuits are scaled down.
[0028] The terms used herein are for the purpose of describing specific example embodiments only and are not intended to limit the present application. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include" and / or "include" when used in this specification specify the presence of stated features, wholes, steps, operations, components, and / or assemblies, but do not exclude the presence of said features, wholes, steps, operations, components, and / or assemblies.
[0029] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.
[0030] Hereinafter, exemplary embodiments will be explained in detail with reference to the accompanying drawings.
[0031] Figure 1 Schematic diagram of a micro-LED array according to some embodiments of the present application. Referring to FIG. 1, a micro-LED array 10 is shown. In some embodiments, the micro-LED array 10 may include a micro-LED 100, an isolation structure 200, a compound semiconductor layer 300, and a refractive index adjustment layer 400. The micro-LED array 10 is configured to transmit light emitted by the micro-LED 100 through the compound semiconductor layer 300 and the refractive index adjustment layer 400 to a display system, such as a mobile phone, a computer, a television, and other electronic products.
[0032] In some embodiments, the micro-LED 100 is configured to convert electrical energy into light energy and emit light. In some embodiments, the micro-LED 100 may include an n-type semiconductor layer 110, an active layer 120, a p-type semiconductor layer 130, a transparent conductive layer 140, and a contact layer 150. In some embodiments, the micro-LED array 10 further includes a bonding pad 160 and / or an intermetallic dielectric layer 170.
[0033] In some embodiments, the n-type semiconductor layer 110 covers the active layer 120 and is located below the compound semiconductor layer 300, and its left and right sides contact the isolation structure 200. In some embodiments, the n-type semiconductor layer 110 can be a semiconductor material, such as GaN.
[0034] In some embodiments, the active layer 120 covers the p-type semiconductor layer 130 and is located below the n-type semiconductor layer 110, and its left and right sides contact the isolation structure 200. In some embodiments, the active layer 120 can be a multiple quantum well (MQW) layer.
[0035] In some embodiments, the p-type semiconductor layer 130 covers the transparent conductive layer 140 and is located below the active layer 120, and its left and right sides contact the isolation structure 200. In some embodiments, the p-type semiconductor layer 130 can be a semiconductor material, such as GaN. In some embodiments, the n-type semiconductor layer 110, the active layer 120, and the p-type semiconductor layer 130 include electrons and holes, wherein the electrons and holes can generate photons after radiation recombination.
[0036] In some embodiments, the transparent conductive layer 140 covers the contact layer 150 and is located below the p-type semiconductor layer 130, and its left and right sides contact the isolation structure 200. In some embodiments, the transparent conductive layer 140 can be a transparent conductive oxide, such as indium tin oxide (ITO).
[0037] In some embodiments, the contact layer 150 is located above the pad 160 and below the transparent conductive layer 140, and its left and right sides partially contact the isolation structure 200, and partially contact the intermetallic dielectric layer 170. Specifically, the isolation structure 200 isolates the n-type semiconductor layer 110, the active layer 120, the p-type semiconductor layer 130, the transparent conductive layer 140, and a portion of the contact layer 150 in the intermetallic dielectric layer 170. In other words, the upper portion of the contact layer 150 that is more in contact with the transparent conductive layer 140 is partially covered by the isolation structure 200, and the lower portion of the contact layer 150 that is more in contact with the pad 160 is exposed in the intermetallic dielectric layer 170 and the bottom portion contacts the pad 160. In some embodiments, the contact layer 150 may be a metal material, such as Ti, Al, or TiN.
[0038] In some embodiments, the pad 160 is located below the contact layer 150 and in the intermetallic dielectric layer 170. In some embodiments, the pad 160 may be a metal material, such as Cu.
[0039] In some embodiments, the intermetallic dielectric layer 170 is located between the plurality of micro-LEDs 100. Specifically, the intermetallic dielectric layer 170 is located between the isolation structures 200 of the plurality of micro-LEDs 100, the contact layer 150 in contact with the plurality of isolation structures 200, and the pads 160 in contact with the plurality of contact layers 150. In some embodiments, the intermetallic dielectric layer 170 may be a dielectric material, such as SiO 2 or Si 3 N 4 In some embodiments, since the contact layer 150 and the bonding pad 160 have conductive properties, the intermetallic dielectric layer 170 is disposed to electrically isolate the contact layer 150 and the bonding pad 160 of each micro-LED 100 .
[0040] In some embodiments, the isolation structure 200 is located between the plurality of micro-LEDs 100 and is configured to electrically isolate each micro-LED 100. In some embodiments, the isolation structure 200 may be a passivation layer, and its material may be an insulating material, such as Al 2 O 3 or Si 3 N 4 In some embodiments, the isolation structure 200 can prevent the lights emitted by adjacent micro-LEDs 100 from interfering with each other.
[0041] In some embodiments, the compound semiconductor layer 300 covers the micro-LED 100 and the isolation structure 200. Specifically, the compound semiconductor layer 300 covers the n-type semiconductor layer 110 and the isolation structure 200. In some embodiments, the thickness of the compound semiconductor layer 300 is thicker than the thickness of the n-type semiconductor layer 110, the active layer 120, the p-type semiconductor layer 130, the transparent conductive layer 140 and / or the contact layer 150. In some embodiments, the compound semiconductor layer 300 has a refractive index that is higher than the refractive index of air. In some embodiments, the compound semiconductor layer 300 can be a semiconductor material, such as GaN. For blue light with a wavelength of about 460nm, the refractive index of GaN, the material of the compound semiconductor layer 300, is as high as about 2.45, which is quite different from the refractive index of air of about 1.00.
[0042] In some embodiments, the refractive index adjustment layer 400 covers the compound semiconductor layer 300. In some embodiments, a portion of the isolation structure 200 is separated from the refractive index adjustment layer 400 via the compound semiconductor layer 300. On the other hand, a portion of the isolation structure 200 may pass through the compound semiconductor layer 300 and contact the refractive index adjustment layer 400. In other words, the refractive index adjustment layer 400 covers the compound semiconductor layer 300 and contacts a portion of the isolation structure 200.
[0043] The refractive index adjustment layer 400 is configured to reduce the difference between the light output interface and the refractive index of air to increase the light extraction efficiency. Specifically, the refractive index adjustment layer 400 has a refractive index that is greater than the refractive index of air and less than the refractive index of the compound semiconductor layer 300, so as to be closer to the refractive index of air to increase the light extraction efficiency. For example, the refractive index of the refractive index adjustment layer 400 may be greater than 1.5 and less than 2.5. In some embodiments, the refractive index adjustment layer 400 is a high refractive index resin layer, and the refractive index is approximately 1.75. In some embodiments, the high refractive index resin layer is a polymer, which is a high molecular compound formed by repeatedly linking many small molecular monomers, and can be divided into natural polymers and synthetic polymers according to the source. In some embodiments, the high refractive index resin layer may include ZrO 2 and / or TiO 2 etc. to achieve the characteristics of high refractive index.
[0044] Figure 2 Schematic diagram of light extraction efficiency of a micro-LED array according to some embodiments of the present application. The light extraction efficiency of a light emitter is defined as the ratio of the external quantum efficiency of the LED to the internal quantum efficiency of the LED. Generally speaking, the light extraction efficiency of a packaged LED is substantially less than 1, that is, part of the light generated in the active area of the LED does not reach the external environment. The light extraction efficiency is usually reduced by total internal reflection due to the refractive index difference between the active area of the LED and the interface of the surrounding material, and the subsequent reabsorption of the internally reflected light in the LED.
[0045] Snell's law states that when a light wave propagates from a first medium to a second medium, refraction will occur if the refractive index of the first medium is different from that of the second medium. According to Snell's law, n 1 sinθ 1 = n 2 sinθ 2 , where n 1 is the refractive index of medium 1, n 2 is the refractive index of medium 2, with a normal line as the reference, θ 1 is the incident angle of light from medium 1 into medium 2, and θ 2 is the refraction angle of light. The incident ray, refracted ray and normal are all on the same plane, the incident ray and refracted ray are on both sides of the normal, and the sine ratio of the incident angle and the refraction angle is a certain value. The total reflection angle means θ 2 is 90°.
[0046] refer to Figure 2In the embodiment with the added refractive index adjustment layer 400, the compound semiconductor layer 300 covers the micro-LED 100 and the isolation structure 200, and the refractive index adjustment layer 400 covers the compound semiconductor layer 300 and contacts the external environment 50. In some embodiments, the external environment 50 is air with a refractive index of about 1.00. In some embodiments, the material of the refractive index adjustment layer 400 is a high refractive index resin layer, and the refractive index is about 1.75 for blue light with a wavelength of about 460nm, while the refractive index of the compound semiconductor layer 300 is about 2.45. The refractive index of the refractive index adjustment layer 400 is between the refractive index of the compound semiconductor layer 300 and the refractive index of air, so that the light of the light source, such as the micro-LED 100, is less likely to form total reflection or reflection at the light output interface 517 to reduce the light extraction efficiency. The detailed principle will be described below.
[0047] As shown in the figure, in the embodiment with the added refractive index adjustment layer 400, the compound semiconductor layer 300 is a compound semiconductor (refractive index is about 2.45), the material of the refractive index adjustment layer 400 is a high refractive index resin layer (refractive index is about 1.75), and the external environment 50 is air (refractive index is about 1.00). According to Snell's law, 2.45 (sinθ 1 ) = 1.75 (sin90°), the total reflection angle θ of the light 505 at the light exit interface 517 between the compound semiconductor layer 300 and the refractive index adjustment layer 400 1 is 45.58°, which means that about 49.36% of the light sources cannot smoothly emit light from the compound semiconductor layer 300, and the light extraction efficiency is about 50.64%. In more detail, when the micro-LED 100 emits light 505 to the refractive index adjustment layer 400, it forms an incident angle α1 with the light-emitting interface 517. If the incident angle α1 is less than 45.58°, the light 505 emitted by the micro-LED 100 falls into the effective light source area 510. Conversely, if the incident angle α1 is greater than or equal to 45.58°, the light 505 emitted by the micro-LED 100 falls into the invalid light source area 511 (that is, it is totally reflected). By calculating (45.58°×2) / 180°, the effective light source area 510 accounts for about 50.64% of the total emission light source area, which means that about 50.64% of the light sources can smoothly emit light from the compound semiconductor layer 300.
[0048] However, in the embodiment without adding the refractive index adjustment layer 400 (ie Figure 2The refractive index adjustment layer 400 does not exist), the compound semiconductor layer 300 will directly contact the external environment 50. That is, the light-emitting surface of the compound semiconductor layer 300 will be directly exposed to the external environment 50. In this case, due to the large difference between the reflectivity of the compound semiconductor layer 300 and the reflectivity of the external environment 50 (such as air), according to Snell's law, this will cause the angle of total reflection to drop to 24.09°. In other words, when the incident angle α1 between the light 505 and the light-emitting interface 517 is greater than or equal to 24.09°, total reflection will occur, causing the light extraction efficiency to drop to 26.78%, which means that about 73.21% of the light sources cannot smoothly emit light from the compound semiconductor layer 300.
[0049] It can be seen that the present application adds a refractive index adjustment layer 400 between the compound semiconductor layer 300 and the external environment 50 in the micro-LED array 10, which can increase the area of the effective light source region 510 of the compound semiconductor layer 300, that is, higher light extraction efficiency.
[0050] It should be understood that the above discussion uses the refractive index adjustment layer 400 having a refractive index of 1.75 as an example, but the present application is not limited to this. In other embodiments, the refractive index of the added refractive index adjustment layer 400 is about 1.90, and the compound semiconductor layer 300 is also a compound semiconductor (refractive index of about 2.45). Calculated by the above method, in the embodiment where the added refractive index adjustment layer 400 is a high refractive index resin (refractive index of about 1.90), the total reflection angle θ of the light exit interface 517 is 2 The angle is 50.85°, the effective light source area 510 accounts for about 56.50% of the total emission light source area, and the ineffective light source area 511 accounts for about 43.50% of the total emission light source area, which has a higher light extraction efficiency.
[0051] Figure 3ASchematic diagram of a micro-LED array according to some embodiments of the present application. In some embodiments, the micro-LED array 10 includes at least one groove 60, which penetrates the refractive index adjustment layer 400 and a portion of the compound semiconductor layer 300. In some embodiments, the groove 60 is located in a portion of the compound semiconductor layer 300 above the isolation structure 200. In some embodiments, the groove 60 has a width, which is approximately the same as the top surface width of the isolation structure 200. In some embodiments, the groove 60 has a depth, and the depth does not penetrate the entire compound semiconductor layer 300. Therefore, at least a portion of the compound semiconductor layer 300 is located between the bottom of the groove 60 and the isolation structure 200 in the vertical direction. In some embodiments, the groove 60 is configured to guide light with a more biased emission angle back to the original light emitting area of the micro-LED 100. In some embodiments, the groove 60 can be formed by dry etching or wet etching. In some embodiments, the area of the groove 60 can be an external environment 50, such as air, or other materials with adjustable refractive index. It should be understood that Figure 3A Only one groove 60 is shown in the figure, however, the micro-LED array 10 may have a plurality of grooves 60 , and each groove 60 is located between two adjacent micro-LEDs 100 and above a corresponding isolation structure 200 .
[0052] Figure 3B FIG. 1 is a schematic diagram of light extraction efficiency of a micro-LED array according to some embodiments of the present application. More specifically, Figure 3B The effect of adding a trench 60 on light extraction efficiency is further depicted. Figure 3B The discussion is based on the assumption that the compound semiconductor layer 300 has a refractive index of 2.45, the refractive index adjustment layer 400 has a refractive index of 1.75, and the external environment 50 has a refractive index of 1.00. Please note that Figure 3B Only the right half of the light emitted by a micro-LED 100 is depicted, and only a partial angle of the light is used as an illustration. In some embodiments, Figure 3B The depicted right half of the ray is a mirror image of its left half (not shown) and can be flipped horizontally at a 90° vertical line from which the light emerges.
[0053] exist Figure 3B In the embodiment, the compound semiconductor layer 300 and the groove 60 can form a light output interface 518. In some embodiments, the region of the groove 60 can be exposed to the external environment 50, such as air. As discussed above, the total reflection angle of the interface between the compound semiconductor layer 300 and air is known to be 24.09°. If the incident angle α2 of the light 505 emitted by a micro-LED 100 at the light output interface 518 is about 24.09°, the light 505 will be totally reflected at the light output interface 518.
[0054] As the incident angle α2 gradually increases, the light 505 toward the groove 60 will continue to be totally reflected. When the incident angle α3 of the light 505 at the light output interface 518 is 44.42°, the light reflected by the light output interface 518 will travel to the light output interface 517 and generate an incident angle α4, wherein the incident angle α4 is 45.58°. As mentioned above, 45.58° is the angle at which the light is totally reflected at the compound semiconductor layer 300 and the refractive index adjustment layer 400. In other words, if the incident angle α3 of the light 505 at the light output interface 518 is further increased, when the incident angle α5 of the light 505 at the light output interface 518 is greater than 45.58°, the light reflected from the light output interface 518 will travel to the light output interface 517 and generate an incident angle α6, wherein the incident angle α6 will be less than 45.58°, so that the reflected light will have the opportunity to generate refracted light that penetrates the light output interface 517 of the compound semiconductor layer 300.
[0055] It can be seen that if the incident angle of the light 505 emitted by a micro-LED 100 at the light-emitting interface 518 is greater than or equal to 24.09°, the light 505 can be guided back to the light-emitting area of the original micro-LED 100. Further, in some embodiments, when the incident angle of the light 505 emitted by a micro-LED 100 at the light-emitting interface 518 is greater than 44.42°, the light can not only be guided back to the light-emitting area of the original micro-LED 100, but also has the opportunity to generate refracted light that penetrates the light-emitting interface 517 of the compound semiconductor layer 300, thereby increasing the light extraction efficiency of each micro-LED 100.
[0056] Figure 4 Schematic diagram of the refractive index adjustment material of the micro-LED array according to some embodiments of the present application. More specifically, Figure 4 A schematic diagram of adding a low refractive index resin material into the groove 60 is further described.
[0057] In some embodiments, the micro-LED array 10 includes a groove 60 that penetrates the refractive index adjustment layer 400 and a portion of the compound semiconductor layer 300. In some embodiments, the region of the groove 60 may be a material with adjustable refractive index, such as a refractive index adjustment material 600. In some embodiments, the refractive index adjustment material 600 fills all regions of the groove 60. In some embodiments, the refractive index adjustment material 600 is a polymer, which is a high molecular compound formed by repeatedly linking many small molecular monomers, and can be divided into natural polymers and synthetic polymers according to their sources. In some embodiments, the refractive index adjustment material 600 has a refractive index that is less than the refractive index of the compound semiconductor layer 300 and less than the refractive index of the refractive index adjustment layer 400. In some embodiments, the refractive index of the refractive index adjustment material 600 is less than 1.5 and greater than 1.0. In some embodiments, the formation of the refractive index adjustment material 600 in the groove 60 can be through a deposition method.
[0058] In some embodiments, the refractive index adjusting material 600 is disposed to guide the light with a relatively biased emission angle back to the original light emitting area of the micro-LED 100. Figure 3B As shown, the refractive index adjusting material 600 in the groove 60 has a function similar to that of the air in the groove 60, including guiding the light back to the light-emitting area of the original light-emitting micro-LED 100 and / or reducing the light-emitting interference of the adjacent micro-LED 100. In some embodiments, the refractive index adjusting layer 400 is a high-refractive index resin, and the refractive index adjusting material 600 is a low-refractive index resin, that is, the refractive index of the refractive index adjusting layer 400 is greater than the refractive index of the refractive index adjusting material 600. In some embodiments, the refractive index adjusting material 600 and the refractive index adjusting layer 400 can be made of the same resin material, but the refractive index adjusting layer 400 further includes ZrO for increasing the refractive index. 2 and / or TiO 2 In other words, the refractive index adjusting material 600 may not have the above-mentioned nanomaterials.
[0059] Figure 5A Schematic diagram of the metal layer of the micro-LED array according to some embodiments of the present application. More specifically, Figure 5A A schematic diagram of adding a metal layer material into the trench 60 is further described.
[0060] In some embodiments, the micro-LED array 10 includes a groove 60 that penetrates the refractive index adjustment layer 400 and a portion of the compound semiconductor layer 300. In some embodiments, the area of the groove 60 may be a reflective material, such as a metal layer 700. In some embodiments, the metal layer 700 may extend along the surface of the groove 60 and cover the light output interface 518, and the external environment 50 such as air fills the remaining area of the groove 60. In some embodiments, the metal layer 700 is a metal substance, such as aluminum (Al). In some embodiments, the metal layer 700 has properties such as luster (strong reflection of visible light), ductility, easy conductivity, and heat transfer. In some embodiments, the metal layer 700 can be formed in the groove 60 by a deposition method. In some embodiments, the metal layer 700 is configured to optically isolate individual micro-LEDs 100 and reflect light with a more biased emission angle back to the original micro-LED 100 light output area. In some embodiments, the same Figure 3B As shown, the metal layer 700 in the groove 60 has a function similar to that of the air in the groove 60 , including guiding the light back to the light emitting area of the original light source micro-LED 100 and / or reducing the light emitting interference of the adjacent micro-LED 100 .
[0061] In some embodiments, the micro-LED array 10 further includes an insulating layer 710, which is located between the metal layer 700 and the compound semiconductor layer 300. In some embodiments, the insulating layer 710 extends between the compound semiconductor layer 300 and the refractive index adjustment layer 400. In some embodiments, the thickness of the insulating layer 710 is less than the thickness of the metal layer 700. In some embodiments, the insulating layer 710 covers the compound semiconductor layer 300, and the refractive index adjustment layer 400 covers a portion of the insulating layer 710. In some embodiments, the insulating layer 710 can be formed in the groove 60 or on the compound semiconductor layer 300 by deposition.
[0062] In some embodiments, the material of the insulating layer 710 may be an insulator, which is a material that does not conduct electricity under voltage, such as SiO 2 In some embodiments, since the compound semiconductor layer 300 and the metal layer 700 have conductive properties, the insulating layer 710 is configured to electrically isolate the compound semiconductor layer 300 and the metal layer 700 .
[0063] Figure 5B Schematic diagram of the metal layer of the micro-LED array according to some embodiments of the present application. More specifically, Figure 5B A schematic diagram of adding a metal layer material into the trench 60 is further described. Figure 5B Similar to Figure 5A , so the relevant details will not be repeated.
[0064] exist Figure 5B In some embodiments, the width of the trench 60 is narrower than the width of the top surface of the isolation structure 200, and the metal layer 700 fills all areas of the trench 60. In some embodiments, the metal layer 700 can be formed in the trench 60 by a deposition method. In some embodiments, since the width of the trench 60 is narrow, the metal layer 700 can fill all areas of the trench 60.
[0065] According to the above discussion, the present application forms a refractive index adjustment layer 400 located between the compound semiconductor layer 300 and the external environment 50 in the micro-LED array 10. This will increase the area of the effective light source region of the compound semiconductor layer 300, that is, a higher light extraction efficiency. On the other hand, the present application further forms a light adjustment structure in the micro-LED array 10, such as the above-mentioned groove 60, refractive index adjustment material 600, and metal layer 700. The light adjustment structure can guide the deviated light back to the light-emitting area of the original micro-LED 100, and has the opportunity to generate refracted light that penetrates the light-emitting interface 517 of the compound semiconductor layer 300, so that the light extraction efficiency of each micro-LED 100 can be further increased.
[0066] The foregoing summarizes the features of several embodiments so that those skilled in the art can better understand the aspects of the present application. Those skilled in the art will appreciate that they can easily use the present application as a basis for designing or modifying other processing procedures and structures for implementing the same purpose and / or achieving the same advantages of the embodiments described herein. Those skilled in the art will also recognize that such equivalent constructions do not depart from the spirit and scope of the present application, and that they may be variously changed, substituted, and modified without departing from the spirit and scope of the present application.
Claims
1. A micro light emitting diode array, characterized in that: include: multiple micro light emitting diodes; an isolation structure located between the plurality of micro light emitting diodes; a compound semiconductor layer covering the plurality of micro-LEDs and the isolation structure, wherein the compound semiconductor layer has a first refractive index; a refractive index adjusting layer covering the compound semiconductor layer, wherein the refractive index adjusting layer has a second refractive index, and the second refractive index is smaller than the first refractive index; and A light adjustment structure penetrates the refractive index adjustment layer and extends into the compound semiconductor layer.
2. The micro light emitting diode array according to claim 1, characterized in that: The second refractive index of the refractive index adjustment layer is greater than a third refractive index of the light adjustment structure.
3. The micro light emitting diode array according to claim 1, characterized in that: The refractive index adjustment layer is a resin layer including ZrO2 or TiO2.
4. The micro light emitting diode array according to claim 1, characterized in that: The light adjustment structure is a groove.
5. The micro light emitting diode array according to claim 1, characterized in that: A third refractive index of the light-adjusting structure is less than the first refractive index of the compound semiconductor layer.
6. The micro light emitting diode array according to claim 1, characterized in that: The light regulating structure extends toward the isolation structure.
7. The micro light emitting diode array according to claim 1, characterized in that: It also includes an insulating layer located between the light regulating structure and the compound semiconductor layer, and the light regulating structure is a metal layer.
8. The micro light emitting diode array according to claim 7, characterized in that: The insulating layer extends between the compound semiconductor layer and the refractive index adjusting layer.
9. The micro light emitting diode array according to claim 1, characterized in that: The light adjustment structure is a metal layer, and the light adjustment structure has an air gap.
10. The micro light emitting diode array according to claim 1, characterized in that: The light adjustment structure is a metal layer, and the light adjustment structure does not have an air gap.