Light emitting diode chip and device

Abstract

The invention relates to a light emitting diode chip and a device. A light emitting diode (LED) chip having a reflective layer of high reflectivity is disclosed. The LED chip may include an active LED structure including an active layer between an n-type layer and a p-type layer. The first reflective layer is adjacent to the active LED structure and includes a plurality of dielectric layers having different optical thicknesses. The plurality of dielectric layers may include a plurality of first dielectric layers and a plurality of second dielectric layers of different thicknesses and compositions. The LED chip may also include a second reflective layer including a conductive path through the first reflective layer. The adhesive layer may be disposed between the first reflective layer and the second reflective layer. The adhesive layer may include a metal oxide that facilitates improved adhesion and reduced optical loss.

Description

[0001] This application is a divisional application with application date of January 28, 2019, application number 201980016062.2, and invention name “Reflective layer of light-emitting diode”, all contents of which are incorporated herein by reference.

[0002] Related Applications

[0003] This application claims the benefit of U.S. patent application Ser. No. 15 / 882,103, filed Jan. 29, 2018, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present disclosure relates to a solid-state lighting device including a light emitting diode, and more particularly, to a light emitting diode having a reflective layer with high reflectivity. Background Art

[0005] Solid-state lighting devices, such as light-emitting diodes (LEDs), are increasingly used in consumer and commercial applications. Advances in LED technology have resulted in light sources that are highly efficient and mechanically robust with long lifetimes. As a result, modern LEDs have enabled a variety of new display applications and are increasingly used in general lighting applications, often replacing incandescent and fluorescent light sources.

[0006] An LED is a solid-state device that converts electrical energy into light, typically including one or more active layers (or active regions) of semiconductor material disposed between oppositely doped n-type and p-type layers. When a bias is applied to the doped layers, holes and electrons are injected into the one or more active layers, where they recombine to produce emission, e.g., visible or ultraviolet light emission. The active region may be made of, for example, silicon carbide, gallium nitride, gallium phosphide, aluminum nitride, and / or gallium arsenide-based materials and / or organic semiconductor materials. Photons generated by the active region are excited in all directions.

[0007] Generally, it is desirable to operate an LED at the highest light emission efficiency, which can be measured by the emission intensity relative to the output power (e.g., in lumens / watt). A practical goal of improving emission efficiency is to maximize the extraction of light emitted from the active area in the desired direction of light transmission. Light extraction and the external quantum efficiency of an LED are limited by many factors, including internal reflections. According to the well-known Snell's law, photons that reach the surface (interface) between the LED surface and the surrounding environment are refracted or reflected internally. If the photons are reflected internally in a repetitive manner, they will eventually be absorbed and never provide visible light emitted from the LED.

[0008] To increase the chance of a photon leaving the LED, it has been found useful to pattern, roughen, or texturize the interface between the LED surface and the surrounding environment to provide a varying surface that increases the probability of refraction for internal reflections, thereby enhancing light extraction. Despite these approaches, their practical application is limited in at least some cases. For example, mechanical methods may introduce stresses in the LED material or cause it to break, and may also be limited in the locations in the manufacturing sequence where they can be used. Chemical (e.g., photolithographic etching) methods may also be limited in their locations in the manufacturing sequence to avoid misalignment or microfeature damage during subsequent LED chip fabrication, and / or to avoid chemical incompatibilities with LED chip layers if etching is performed after chip fabrication.

[0009] Another way to improve light extraction efficiency is to provide a reflective surface that reflects the generated light so that this light can contribute to the emission of useful light from the LED chip. Figure 1 In the typical LED package 10 shown, a single LED chip 12 is mounted on a reflective cup 13 by soldering or conductive epoxy. One or more wire bonds 11 can connect the ohmic contacts of the LED chip 12 to leads 15A and / or 15B, which can be attached to or integral with the reflective cup 13. The reflective cup can be filled with an encapsulation material 16, which can contain a wavelength conversion material, such as a phosphor. At least a portion of the light of the first wavelength emitted by the LED can be absorbed by the phosphor, which can emit light of a second wavelength in response. The entire assembly is then encapsulated in a transparent protective resin 14, which can be molded into the shape of a lens to collimate the light emitted from the LED chip 12. Although the reflective cup 13 can direct light upward, light losses occur when the light is reflected. Since the reflectivity of the actual reflector surface is less than 100%, the reflective cup may absorb some light. The reflectivity of some metals may be less than 95% in the wavelength range of interest.

[0010] Figure 2Another LED package is shown in which one or more LED chips 22 may be mounted on a carrier, such as a printed circuit board (PCB) carrier, substrate or base plate 23. A metal reflector 24 mounted on the base plate surrounds the LED chip 22 and reflects light emitted by the LED chip 22 away from the package 20. The reflector 24 also provides mechanical protection for the LED chip 22. One or more wire bond connections 11 are formed between ohmic contacts on the LED chip 22 and electrical traces 25A, 25B on the base plate 23. The mounted LED chip 22 is then covered with an encapsulant 26, which can provide environmental and mechanical protection for the chip while also acting as a lens. The metal reflector 24 is typically attached to the carrier by solder or epoxy bonding. The metal reflector 24 may also experience optical losses when reflecting light because it also has a reflectivity of less than 100%.

[0011] Figure 1 and Figure 2 The reflector shown in is arranged to reflect light escaping from the LED. LEDs with internal reflective surfaces or layers have also been developed to reflect light inside the LED. Figure 3 A schematic diagram of an LED chip 30 is shown, wherein an LED 32 is mounted on a substrate 34 via a metal bonding layer 36. The LED also includes a p-contact / reflector 38 between the LED 32 and the metal bonding layer 36, wherein the p-contact / reflector 38 typically includes a metal such as silver (Ag). This arrangement is used in commercial LEDs, for example, The company's LED, EZBright LED TM series. The p-contact / reflector 38 can reflect light emitted from the active area of ​​the LED chip back toward the substrate to the primary emitting surface of the LED. The reflector also reflects total internal reflected light back to the primary emitting surface of the LED. Like the metal reflector above, the p-contact / reflector 38 reflects less than 100% of the light, and in some cases less than 95%.

[0012] Figure 4A graph 40 is shown showing the reflectivity of silver on gallium nitride (GaN) at different viewing angles for light having a wavelength of 460 nm. The refractive index of GaN is about 2.4, and the complex refractive index of silver is taken from the technical literature. [See Handbook of Optical Constants of Solids, edited by E. Palik]. The graph shows p-polarized reflectivity 42, s-polarized reflectivity 44, and average reflectivity 46, where average reflectivity 46 generally shows the total reflectivity of a metal used for an LED, where light is produced with random polarization. The reflectivity at 0° is lower than the reflectivity at 90°, and this difference can result in up to 5% or more of light being lost per reflection. In an LED chip, in some cases, the totally internally reflected light reflects from the reflector several times before escaping, and therefore, small changes in reflector absorption can result in significant changes in LED brightness. The cumulative effect of reflector absorption on each reflection reduces the light intensity so that less than 75% of the light from the LED active area actually escapes as LED light.

[0013] The art continues to seek improved light emitting diodes and solid state lighting devices having reduced light losses and providing desirable lighting characteristics that overcome challenges associated with conventional lighting devices. Summary of the invention

[0014] The present disclosure relates to a solid-state lighting device including a light emitting diode, and more particularly, to a light emitting diode having a reflective layer with high reflectivity.

[0015] In some embodiments, a light emitting diode (LED) chip includes: an active LED structure including an active layer between an n-type layer and a p-type layer; a first reflective layer adjacent to the active LED structure and including a plurality of dielectric layers. The LED chip includes: a second reflective layer on the first reflective layer; a barrier layer on the second reflective layer; and a passivation layer on the barrier layer. In some embodiments, each of the plurality of dielectric layers includes a different thickness. In some embodiments, the plurality of dielectric layers includes a plurality of first dielectric layers and a plurality of second dielectric layers. In some embodiments, the plurality of dielectric layers includes a non-periodic Bragg reflector. In some embodiments, the second reflective layer includes a conductive path through the first dielectric layer.

[0016] In other embodiments, a light emitting diode (LED) chip includes: an active LED structure including an active layer between an n-type layer and a p-type layer; and a first reflective layer adjacent to the active LED structure and including a plurality of first dielectric layers and a plurality of second dielectric layers, wherein each of the plurality of first dielectric layers includes a different thickness. The thickest layer of the plurality of first dielectric layers is located between the other layers of the plurality of first dielectric layers.

[0017] In other embodiments, an LED chip includes: an active LED structure including an active layer between an n-type layer and a p-type layer; and a first reflective layer adjacent to the active LED structure and including a plurality of first dielectric layers and a plurality of second dielectric layers. The average thickness of the plurality of first dielectric layers is greater than the average thickness of the plurality of second dielectric layers, and the thickness of at least one of the plurality of second dielectric layers is greater than the thickness of at least one of the plurality of first dielectric layers.

[0018] In other embodiments, a light emitting diode (LED) chip includes: an active LED structure including an active layer between an n-type layer and a p-type layer; a first reflective layer adjacent to the active LED structure; a second reflective layer on the first reflective layer; and an adhesive layer between the first reflective layer and the second reflective layer, wherein the adhesive layer includes a metal oxide. In some embodiments, the first reflective layer may include a plurality of dielectric layers. In some embodiments, the metal oxide includes aluminum oxide or anodized aluminum oxide.

[0019] In another aspect, any one or more aspects, embodiments, or features described herein may be combined with any one or more other aspects or features to achieve additional advantages.

[0020] Those skilled in the art will understand the scope of the present disclosure and recognize additional aspects thereof after reading the following detailed description of the preferred embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0022] Figure 1 is a cross-sectional view of a conventional light emitting diode (LED);

[0023] Figure 2 This is a cross-sectional view of a conventional LED;

[0024] Figure 3 This is a partial cross-sectional view of a conventional LED;

[0025] Figure 4 is a graph showing the reflectivity of a metal reflector at different viewing angles;

[0026] Figure 5A is a partial cross-sectional view of an LED according to some embodiments;

[0027] Figure 5B is a partial cross-sectional view of a reflective layer of an LED according to some embodiments;

[0028] Figure 5C is a partial cross-sectional view of a reflective layer of an LED according to some embodiments;

[0029] Figure 5D is a partial cross-sectional view of a reflective layer of an LED according to some embodiments;

[0030] Figure 5E is a partial cross-sectional view of a reflective layer of an LED according to some embodiments;

[0031] Fig. 6A is a graph comparing the percent reflectance of some embodiments over a wide wavelength range at zero degree angle of incidence;

[0032] Figure 6B is a heat map representation comparing the reflected intensity over a wide range of angles of incidence (AOI) and a wide range of wavelengths for some embodiments;

[0033] Figure 6C is a heat map representation comparing the reflected intensity over a wide range of angles of incidence (AOI) and a wide range of wavelengths for some embodiments;

[0034] Figure 7 is a graph showing reflectivity of a reflective layer at different viewing angles according to some embodiments;

[0035] Fig. 8A is a cross-sectional view of an LED according to some embodiments;

[0036] Figure 8B is a cross-sectional view of an LED according to some embodiments;

[0037] Fig. 9A is a microscopic cross-sectional image of a portion of an LED according to some embodiments;

[0038] Fig. 9B is a cross-sectional view of a portion of an LED chip near an active structure hole according to some embodiments;

[0039] Fig. 9C is a cross-sectional view of a portion of an LED chip near a hole in a reflective layer according to some embodiments;

[0040] Fig. 10A is a cross-sectional view of an LED according to some embodiments;

[0041] Fig. 10B is a cross-sectional view of an LED according to some embodiments;

[0042] Fig.11A is a cross-sectional view of an LED according to some embodiments;

[0043] Fig. 11B is a cross-sectional view of an LED according to some embodiments;

[0044] Fig. 12Ais a cross-sectional view of an LED according to some embodiments;

[0045] Fig. 12B is a cross-sectional view of an LED according to some embodiments;

[0046] Fig.13 is a cross-sectional view of a packaged LED according to some embodiments;

[0047] Fig.14 is a cross-sectional view of a packaged LED according to some embodiments;

[0048] Fig.15 is a cross-sectional view of a multi-junction LED chip according to some embodiments;

[0049] Fig.16 is a cross-sectional view of a portion of a lighting fixture according to some embodiments;

[0050] Fig.17A This is a scanning electron microscope image of the Al2O3 film surface magnified about 10,000 times;

[0051] Fig. 17B It is magnified about 50,000 times. Fig.17A Scanning electron microscope image of the Al2O3 film surface;

[0052] Fig.18A is a cross-sectional view according to an embodiment disclosed herein, including an adhesive layer having a controlled morphology or grain structure between a first reflective layer and a second reflective layer;

[0053] Fig.18B The first reflective layer is removed. Fig.18A A bottom view of a first surface of the adhesive layer;

[0054] Fig.19A is a cross-sectional representation according to an embodiment disclosed herein, including an adhesive layer having a different controlled morphology or grain structure between a first reflective layer and a second reflective layer;

[0055] Fig.19B The first reflective layer is removed. Fig.19A A bottom view of a first surface of the adhesive layer;

[0056] Fig. 20 is a plot showing ellipsometry measurements of Al2O3 films. DETAILED DESCRIPTION

[0057] The embodiments set forth below represent the necessary information to enable those skilled in the art to practice these embodiments, and show the best mode for practicing these embodiments. After reading the following description according to the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure, and will recognize the application of these concepts not specifically mentioned herein. It should be understood that these concepts and applications fall within the scope of the present disclosure and the appended claims.

[0058] It should be understood that although the terms first, second, etc. can be used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present disclosure, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more related listed items.

[0059] It should be understood that when an element such as a layer, region or substrate is referred to as being on another element or extending onto another element, it can be directly on another element or directly extending onto another element, or there can also be an intermediate element. On the contrary, when an element is referred to as being "directly on another element" or "extending directly onto another element", there is no intermediate element. Similarly, it should be understood that when an element such as a layer, region or substrate is referred to as being "on" another element or extending "on" another element, it can be directly on another element or directly extending onto another element, or there can also be an intermediate element. On the contrary, when an element is referred to as being "directly on" another element or extending "directly on" another element, there is no intermediate element. It should also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to another element, or there can be an intermediate element. On the contrary, when an element is referred to as being "directly connected" or "directly coupled" to another element, there is no intermediate element.

[0060] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe the relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It should be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0061] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when used herein, the terms "comprises, comprising", and / or "includes, including" specify the presence of the features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0062] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It should also be understood that the terms used herein should be interpreted as having the same meaning as they have in the context of this specification and the relevant art, and will not be interpreted as idealized or overly formal unless explicitly defined herein.

[0063] The present disclosure relates to solid-state emitters having internal or integral reflective surfaces / layers that are configured to increase the emission efficiency of the emitter. The present disclosure is described herein with reference to light emitting diodes (LEDs), but it should be understood that the present disclosure is equally applicable to other solid-state emitters. The devices of the present disclosure may be used as reflectors in conjunction with one or more contacts, or may be used as reflectors separate from the contacts.

[0064] As described above, different embodiments of the LED chip according to the present disclosure include an active LED structure having an active layer between two oppositely doped layers. It should be understood that the active LED structure may include many additional layers, and the active layer may include multiple layers, and the two oppositely doped layers may also include multiple layers. The first reflective layer may be disposed adjacent to one of the reversely doped layers, the first layer comprising a material having a different refractive index from the active LED structure. In some embodiments, the first reflective layer may include a layer having a refractive index that is primarily lower at or near its interface with the active LED structure. In other words, when the layer includes multiple materials, some embodiments of the layer may have an average refractive index lower than the active LED structure. In other embodiments, the portion of the reflective layer closest to the active LED structure should be smaller than the portion of the active LED structure.

[0065] The refractive index difference between the active LED structure and the first reflective layer increases the amount of total internally reflected (TIR) ​​light at the interface. In embodiments where the refractive index of the first reflective layer is lower than the refractive index of the active LED structure, the lower refractive index material provides a reduction in refractive index, which increases the amount of light that can experience TIR. Some embodiments of the LED chip according to the present disclosure may also include a second reflective layer or a metal layer that may be on and used in conjunction with the first reflective layer so that light that passes through the first reflective layer (e.g., without experiencing TIR) can be reflected by the second reflective layer.

[0066] These internal or integral reflective layers can reduce light emission losses that may be due to light being emitted in an undesirable direction and absorbed. Light emitted from the active LED structure of the emitter in a direction away from useful light emission (e.g., toward a substrate, baseplate, or metal bonding layer) can be reflected by the first reflective layer. The reflective surface can be positioned to reflect the light so that the light is emitted from the LED chip in a desired direction. Embodiments of the present disclosure provide one or more layers and materials that can cooperate to effectively reflect light in a desired direction so that the light can contribute to useful emission from the emitter.

[0067] The first reflective layer can include many different materials, including silicon nitride (SiN, SiNx, Si3N4), silicon (Si), germanium (Ge), silicon oxide (SiO2, SiOx), titanium oxide (TiO2), indium tin oxide (ITO), magnesium oxide (MgOx), zinc oxide (ZnO), and combinations thereof. In some embodiments, the first reflective layer includes a dielectric material, such as silicon dioxide (SiO2) and / or silicon nitride (SiN, Si3N4). It should be understood that many other materials with lower or higher refractive indices can be used, some of which have a refractive index that is up to about 50% less than the refractive index of the active structure material of the LED. In other embodiments, the refractive index of the first reflective material can be up to about 40% less than the refractive index of the active structure material, while in other embodiments, it can be up to about 30% less, and in other embodiments, it can be up to about 20% less. For example, in some embodiments, the refractive index of the GaN material of the active structure is about 2.4, and the reflective material includes one or more layers of silicon dioxide material with a refractive index of about 1.46 and one or more layers of silicon nitride with a refractive index of about 1.9.

[0068] Many traditional LEDs rely primarily on metal reflective layers made of different materials, such as silver (Ag), Ag alloys, gold (Au), and Au alloys. As mentioned above, each reflection of the metal reflector will have losses, and these losses can be large, especially for light that passes and reflects multiple times in the LED. The light reflected by TIR has no optical losses, so the emission efficiency of the LED can be increased when more light is reflected using TIR. Other traditional LED chips rely on internal multilayer reflectors, such as distributed Bragg reflectors (DBRs). Traditional DBRs (e.g., quarter-wave reflectors) include multiple pairs of layers with different refractive indices. Multiple pairs are arranged in sequence to provide multiple interfaces with a refractive index gradient. Each interface between two layers contributes to Fresnel reflection; however, this only occurs within a specific range of incident angles.

[0069] Different embodiments of the emitter according to the present disclosure may also utilize other structures, layers, or features that allow efficient and reliable LED operation. In some embodiments, a current spreading layer may be included near the reflective layer to spread the current into one or more layers of the active LED structure. In other embodiments, materials may be included to provide reliable adhesion between different layers, for example, between a low refractive index layer and a metal reflective layer. Different embodiments of the present disclosure also provide a conductive via or path arrangement that provides a conductive path through the low refractive index reflective layer. This allows electrical signals to pass through the low refractive index layer along the via, so that the composite layer can be used as an inner layer, wherein the electrical signal can pass through the low refractive index layer during operation. As described in detail below, this via arrangement can take many different shapes and sizes.

[0070] The present disclosure is described herein with reference to certain embodiments, but it should be understood that the present disclosure can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Specifically, the first reflective layer of lower refractive index can include many different material layers and can have many different thicknesses beyond those described herein. Some embodiments can have layers including layers or materials having a higher refractive index than the active LED structure, but these layers can be thin enough to have minimal optical impact. The first reflective layer can also be in many different positions on different solid-state emitters other than those described herein, and can be used on different devices other than solid-state emitters. In addition, the first reflective layer can be provided with or without a conductive structure to allow electrical signals to pass through. It should be understood that the LED according to the present disclosure can also utilize the first reflective layer in combination with other reflectors including metal and other dielectric reflective layers. The first reflective layer is configured to increase the amount of light reflected by TIR while maintaining a simple, effective and cost-effective reflection system.

[0071] Embodiments of the present disclosure are described herein with reference to cross-sectional views that are schematic illustrations of embodiments of the present disclosure. Therefore, the actual thicknesses of the layers may vary, and variations in the illustrated shapes may be expected as a result of, for example, manufacturing techniques and / or tolerances. For example, an area shown or described as a square or rectangle may have rounded or curved features, and an area shown as a straight line may have certain irregularities. Therefore, the areas shown in the drawings are schematic, and their shapes are not intended to illustrate the precise shape of an area of ​​the device, nor are they intended to limit the scope of the present disclosure.

[0072] Figure 5A A cross-sectional view of an LED chip 50 according to some embodiments is shown. The LED chip 50 includes a reflective structure that allows the LED chip to operate with greater emission efficiency. Although the present invention is described with reference to the manufacture of a single LED chip, it should be understood that the present invention can also be applied to wafer-level LED chip manufacturing, the manufacture of LED chip groups, or the manufacture of packaged LED chips. The wafer LED or LED group can then be separated into individual LED chips using known segmentation or cutting methods. The present disclosure can also be used for different LEDs having different geometries, for example, lateral geometries or vertical geometries. The present disclosure can also be used in LEDs compatible with flip chip mounting, and in LEDs that are not flip chip mounted.

[0073] The LED chip 50 includes an active LED structure 52 or region, which may have many different semiconductor layers arranged in different ways. The manufacture and operation of LEDs and their active structures are well known in the art and will only be briefly discussed here. The layers of the active LED structure 52 may be manufactured using known processes, using metal organic chemical vapor deposition to manufacture suitable processes. The layers of the active LED structure 52 may include many different layers, and typically include an active layer sandwiched between n-type and p-type oppositely doped epitaxial layers, all of which are formed successively on a growth substrate. It should be understood that additional layers and elements may also be included in the active LED structure 52, including but not limited to buffer layers; nucleation layers; superlattice structures; undoped layers; cladding layers; contact layers; and current diffusion layers and light extraction layers and elements. The active layer may include a single quantum well, a multiple quantum well, a double heterostructure, or a superlattice structure.

[0074] The active LED structure 52 can be made of different material systems, some of which are group III nitride-based material systems. Group III nitrides refer to semiconductor compounds formed between nitrogen and group III elements of the periodic table, typically aluminum (Al), gallium (Ga), and indium (In). Gallium nitride (GaN) is a common binary compound. The term also refers to ternary and quaternary compounds, such as aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), and aluminum indium gallium nitride (AlInGaN). For group III nitrides, silicon (Si) is a common n-type dopant, and magnesium (Mg) is a common p-type dopant. Therefore, for group III nitride-based material systems, the active layer, n-type layer, and p-type layer can include one or more layers of GaN, AlGaN, InGaN, and AlInGaN that are undoped or doped with silicon or magnesium. Other material systems include silicon carbide, organic semiconductor materials, and other group III-V systems, such as gallium phosphide, gallium arsenide, and related compounds.

[0075] The active LED structure 52 can be grown on a substrate ( Figure 5A The growth substrate can be made of many materials, for example, sapphire, silicon carbide, aluminum nitride (AlN), GaN, and a suitable substrate is 4H polytype silicon carbide, although other silicon carbide polytypes, including 3C, 6H and 15R polytypes, can also be used. Silicon carbide has certain advantages, such as a closer lattice match to group III nitrides than other substrates and produces high-quality group III nitride films. Silicon carbide also has very high thermal conductivity, so the total output power of group III nitride devices on silicon carbide is not limited by substrate heat dissipation. Sapphire is another common substrate for group III nitrides and also has certain advantages, including lower cost, established manufacturing processes, and good light-transmitting optical properties.

[0076] Depending on the composition of the active layer and the n-type and p-type layers, different embodiments of the active LED structure 52 can emit light of different wavelengths. In some embodiments, the active LED structure 52 emits blue light with a peak wavelength range of approximately 430nm to 480nm. In other embodiments, the active LED structure 52 emits green light with a peak wavelength range of 500nm to 570nm. In other embodiments, the active LED structure 52 emits red light with a peak wavelength range of 600 to 650nm. The LED chip 50 can also be covered with one or more luminescent phosphors or other conversion materials, such as phosphors, so that at least some of the light from the LED passes through one or more phosphors and is converted into one or more different wavelengths of light. In one embodiment, the LED chip emits a white light combination of light from the LED active structure and light from one or more phosphors. One or more phosphors may include light emitting yellow (e.g., YAG:Ce), green (LuAg:Ce), and red (Ca:Ce).i-x-y Sr x Eu y AlSiN3) phosphors and combinations thereof.

[0077] As described above, different layers may be included to allow for efficient operation of the LED chip 50. For some semiconductor materials, for example, some Group III nitride material systems, current cannot diffuse efficiently through the p-type layer. In these embodiments, a current diffusion layer 54 may be at a location on the active LED structure 52 to help diffuse current into the p-type layer. In some embodiments, the current diffusion layer 54 may cover some or the entire p-type layer, and in some embodiments, the current diffusion layer 54 helps diffuse current from the p-contact onto the surface of the p-type layer, as described in more detail below. This helps provide improved current diffusion on the p-type layer while correspondingly improving current injection from the p-type layer.

[0078] The current spreading layer 54 can include many different materials and is typically a transparent conductive oxide, such as ITO or a metal, such as platinum (Pt), although other materials may be used. The current spreading layer can have many different thicknesses, with the present disclosure having a thickness that is small enough to minimize absorption of light from active structures that passes through the current spreading layer. Some embodiments of the current spreading layer 54 comprising ITO may have a thickness of less than 1000 angstroms. , while other embodiments may have a thickness less than Some embodiments may have a thickness less than Some other embodiments may have a thickness of to range, some of these embodiments have a thickness of approximately The current spreading layer 54 and the reflective layer described below can be deposited using known methods. It should be understood that in embodiments where current spreading is not considered, an LED chip without a current spreading layer can be provided.

[0079] The LED chip 50 may also include a first reflective layer 56 that may be formed on the active LED structure 52, and in the illustrated embodiment, a current spreading layer 54 between the first reflective layer 56 and the active LED structure 52 is formed on the current spreading layer 54. The first reflective layer 56 may include many different materials, and preferably includes a material that presents a refractive index step with the material that includes the active LED structure 52. In other words, the refractive index of the first reflective layer 56 should be less than the refractive index of the active LED structure 52 to promote TIR of the active structure's light emission toward the first reflective layer 56, as shown by the first light trace 58. Light that undergoes TIR is reflected without experiencing absorption or loss, and TIR allows for efficient reflection of the active structure light, so that it can contribute to useful or desired LED chip emission. In embodiments that rely solely on metal layers to reflect light, the light experiences losses at each reflection (as described above), which may reduce the overall LED chip emission efficiency.

[0080] In some embodiments, the first reflective layer 56 comprises a material having a lower refractive index than the material of the active LED structure 52, the lower refractive index material providing greater TIR of light from the active LED structure 52. The first reflective layer 56 may comprise many different materials, some of which have a refractive index less than 2.3, while other materials may have a refractive index less than 2.15, less than 2.0, and less than 1.5. In some embodiments, the first reflective layer 56 comprises a dielectric material, some embodiments comprising silicon dioxide and / or silicon nitride. It should be understood that many dielectric materials may be used, for example, SiN, SiNx, Si3N4, Si, Ge, SiO2, SiOx, TiO2, Ta2O 5、 ITO, MgOx, ZnO and combinations thereof.

[0081] As described above, some Group III nitride materials (e.g., GaN) have a refractive index of about 2.4, silicon dioxide has a refractive index of about 1.48, and silicon nitride has a refractive index of about 1.9. Embodiments having an active LED structure 52 comprising GaN and a first reflective layer 56 comprising silicon dioxide can have a sufficient refractive index step between the two to allow for efficient TIR of light at the junction between the two, as shown by the first light trace 58. Depending on the type of material used, the first reflective layer 56 can have different thicknesses, with some embodiments having a thickness of at least 0.2 micrometers (μm). In some of these embodiments, its thickness can be in the range of 0.2 μm to 0.7 μm, and in some of these embodiments, its thickness can be approximately 0.5 μm.

[0082] When light undergoes TIR at the junction with the first reflective layer 56, an evanescent wave with exponentially decaying intensity can extend into the first reflective layer 56. The wave is strongest within about one-third of the wavelength of light emitted from the junction (in silicon dioxide, 450nm light is about 0.3μm). If the thickness of the first reflective layer 56 is too thin, so that significant intensity remains in the evanescent wave at the interface between the first reflective layer 56 and the second reflective layer 60, a portion of the light can reach the second reflective layer 60. This in turn can reduce TIR reflection at the first interface. To this end, in some embodiments, the first reflective layer 56 should have a thickness of at least 0.3μm.

[0083] As described above, the LED chip 50 according to some embodiments may also utilize a second reflective layer 60, such as a metal layer, on the first reflective layer 56 to reflect any light that may pass through the first reflective layer 56. An example of light reflected by the second reflective layer 60 is shown by a second light trace 62, which first passes through the first reflective layer 56 before being reflected by the second reflective layer 60. The second reflective layer 60 may include many different materials, such as Ag, Au, Al, or a combination thereof, and in this embodiment is Ag. Some embodiments may also include an adhesive layer 64 between the first reflective layer 56 and the second reflective layer 60 to promote adhesion between the two. Many different materials may be used for the adhesive layer 64, such as titanium oxide (TiO, TiO2), titanium oxynitride (TiON, TiO2), titanium nitride oxide ... x O y N), tantalum oxide (TaO, Ta2O5), tantalum oxynitride (TaON), aluminum oxide (AlO, Al x O y ) or a combination thereof, preferably TiON, AlO or Al x O y In this regard, the bonding layer 64 may include a metal oxide. The bonding layer 64 may have a number of different thicknesses ranging from a few angstroms to several thousand angstroms. In some embodiments, the bonding layer 64 may be less than In other embodiments, it may be less than In other embodiments, it may be less than In some of these embodiments, the The thickness of the adhesive layer 64 and the material used should minimize the absorption of the light passing therethrough to minimize the loss of light reflected from the second reflective layer 60. For example, TiON provides good adhesion between the first reflective layer 56 and the second reflective layer 60, but TiON has a high extinction coefficient and is absorptive to wavelengths of approximately 450 nm. In this regard, in embodiments where the adhesive layer 64 includes TiON, the thickness of the adhesive layer 64 may be less than 100 nm. or about To provide good adhesion while reducing absorption of light from the active LED structure 52. x O y The LED structure 52 has a lower extinction coefficient for light having a wavelength of about 450 nm, and therefore absorbs less light generated by the active LED structure 52. In this regard, the bonding layer 64 includes Al x O y In the embodiment of the present invention, the adhesive layer 64 may include a range from about to approximately or range from approximately to approximately or range from approximately to approximately Thickness less than about When some Al x O y Materials may reduce adhesion. At thicknesses greater than approx. When some Al x O y The material may provide a refractive index interface that changes the reflective properties provided by the first reflective layer 56 and the second reflective layer 60. In some embodiments, the bonding layer 64 includes Al x O y , wherein 1≤x≤4 and 1≤y≤6. In some embodiments, the bonding layer 64 includes Al x O y Or Al2O3, where x=2 and y=3. In some embodiments, the bonding layer 64 includes Al x O y Among them, most of Al x O y Including Al2O3, the rest of Al x O y Other x and y values ​​are included. Adhesion layer 64 can be deposited by electron beam deposition, which can provide a smooth, dense and continuous layer without significant changes in surface morphology. Adhesion layer 64 can also be deposited by sputtering, chemical vapor deposition or plasma enhanced chemical vapor deposition.

[0084] As described above, the interface between first reflective layer 56 and active LED structure 52 includes a refractive index step to promote TIR of light, as shown by first light trace 58. However, depending on the angle of incidence, some light may still pass through first reflective layer 56 before being reflected by second reflective layer 60, as shown by second light trace 62. Figure 5B5 shows a cross-sectional view of a first reflective layer 56 according to some embodiments. The first reflective layer 56 includes multiple layers (56-1, 56-2, 56-3, 56-4, 56-5, 56-6, and 56-7) configured to provide multiple different interfaces between them. In addition, layer 56-1 forms an interface with the active LED structure 52, and layer 56-7 forms an interface with the active LED structure 52. Figure 5A Each different interface promotes TIR of light having a different range of incident angles, and thus, the total amount of light reflected by the first reflective layer 56 is increased, and the amount of light reaching the second reflective layer 60 is reduced.

[0085] Different interfaces can be formed by materials with different refractive indices. For example, layer 56-1 may include silicon dioxide, and layer 56-2 may include silicon nitride. Therefore, the interface between layer 56-1 and active LED structure 52 is different from the interface between layer 56-1 and layer 56-2. If two interfaces are provided between the same two materials, the interfaces can be different by changing the optical thickness of each layer. Optical thickness can be defined as the product of the refractive index of the material and the geometric length through which the light path passes. Therefore, the optical thickness of the material layer can be changed by increasing or decreasing the actual layer thickness. A layer with a larger optical thickness generally promotes TIR of light with a shallower angle of incidence compared to another layer with a smaller optical thickness. Therefore, multiple layers with different optical thicknesses allow some layers to reflect more light at shallower angles of incidence, while having other layers that reflect more light at larger angles of incidence, thereby providing increased total reflection for multiple layers at all angles.

[0086] In some embodiments, the first reflective layer 56 includes a plurality of first dielectric layers 56-1, 56-3, 56-5, and 56-7 of a first material and a plurality of second dielectric layers 56-2, 56-4, and 56-6 of a second material different from the first material. If the thickness of each of the plurality of first dielectric layers 56-1, 56-3, 56-5, and 56-7 varies, each interface (i.e., 56-1 and 56-2, 56-2 and 56-3, 56-3 and 56-4, 56-4 and 56-5, and 56-5 and 56-6) will be different, and therefore, each interface can promote TIR of light with a different range of incident angles. In some embodiments, the thickness of each of the plurality of second dielectric layers 56-2, 56-4, and 56-6 can also vary. In some embodiments, the first material is silicon dioxide and the second material is silicon nitride. In other embodiments, the first and second materials may be SiN, SiNx, Si3N4, Si, Ge, SiO2, SiOx, TiO2, Ta2O5, ITO, MgOx, ZnO, or any combination of related materials. Figure 5BAs shown, some embodiments include an odd number of first dielectric layers and an even number of second dielectric layers. In other embodiments, the number of first dielectric layers is equal to the number of second dielectric layers. The thickness of the plurality of first dielectric layers 56-1, 56-3, 56-5, and 56-7 can vary in different configurations within the first reflective layer 56. For example, the thickness of each of the plurality of first dielectric layers 56-1, 56-3, 56-5, and 56-7 can increase or decrease sequentially within the first reflective layer 56. In other embodiments, the thickest layer (in Figure 5B The thickest layer (shown as layer 56-3) is located between other layers (56-1, 56-5 and 56-7) of the plurality of first dielectric layers 56-1, 56-3, 56-5 and 56-7. Figure 5B Layer 56-3 in the first reflective layer 56 has the longest optical thickness and is advantageously used to promote TIR of light having the shallowest incident angles (e.g., 0 to 15°) compared to the other layers (layers 56-1, 56-5, and 56-7). By placing the thickest layer (layer 56-3) between the other layers (layers 56-1, 56-5, and 56-7), at least some light having larger incident angles (e.g., greater than 15°) can be reflected earlier without being potentially lost to absorption within the first reflective layer 56. Figure 5B , the thickest layer among the plurality of first dielectric layers 56 - 1 , 56 - 3 , 56 - 5 , and 56 - 7 is illustrated as layer 56 - 3 ; however, layer 56 - 5 may also be the thickest layer without departing from the principles of these embodiments.

[0087] Thus, some embodiments disclosed herein include an LED chip including a first reflective layer including a plurality of dielectric layers having different optical thicknesses. In some embodiments, the LED chip includes an active structure including an active layer between an n-type layer and a p-type layer; a first reflective layer adjacent to the active LED structure and including a plurality of first dielectric layers and a plurality of second dielectric layers, wherein each of the plurality of first dielectric layers includes a different thickness; wherein the thickest layer of the plurality of first dielectric layers is located between other layers of the plurality of first dielectric layers.

[0088] In some embodiments, the average thickness of the plurality of first dielectric layers 56-1, 56-3, 56-5, and 56-7 is greater than the average thickness of the plurality of second dielectric layers 56-2, 56-4, and 56-6. However, in some embodiments, at least one of the plurality of second dielectric layers 56-2, 56-4, and 56-6 has a thickness greater than at least one of the plurality of first dielectric layers 56-1, 56-3, 56-5, and 56-7. For example, the plurality of first dielectric layers 56-1, 56-3, 56-5, and 56-7 may include silicon dioxide, and the plurality of second dielectric layers 56-2, 56-4, and 56-6 may include silicon nitride, and the thickness of layer 56-1 is 190 nm to 200 nm, the thickness of layer 56-2 is 50 nm to 60 nm, the thickness of layer 56-3 is 335 nm to 345 nm, the thickness of layer 56-4 is 55 nm to 65 nm, the thickness of layer 56-5 is 75 nm to 85 nm, the thickness of layer 56-6 is 60 nm to 70 nm, and the thickness of layer 56-7 is 45 nm to 55 nm. In some embodiments, the average thickness of the plurality of first dielectric layers is at least 2 times greater than the average thickness of the plurality of second dielectric layers. In other embodiments, the average thickness of the plurality of first dielectric layers is at least 3 times greater than the average thickness of the plurality of second dielectric layers.

[0089] Figure 5C FIG. 4 shows a cross-sectional view of the first reflective layer 56 according to other embodiments. Figure 5C In the embodiment, the first reflective layer 56 includes a plurality of layers (56-1, 56-2, 56-3, 56-4, 56-5, 56-6, 56-7, 56-8, 56-9, 56-10, 56-11, 56-12, 56-13) configured to provide a plurality of different interfaces therebetween. Figure 5A The interface of the active LED structure 52, and the layer 56-7 is formed with Figure 5A The first reflective layer 56 includes a plurality of first dielectric layers 56-1, 56-3, 56-5, 56-7, 56-9, 56-11, and 56-13 of a first material and a plurality of second dielectric layers 56-2, 56-4, 56-6, 56-8, 56-10, and 56-12 of a second material different from the first material. The first material and the second material may be the same as those described above for the first reflective layer 56. Figure 5B The thickness of each of the plurality of first dielectric layers and each of the plurality of second dielectric layers may be as described above for Figure 5B Changes as described.

[0090] exist Figure 5C The thickest layer is shown as layer 56-1, which is Figure 5A The active LED structure forms an interface. Figure 5B The thickest layer ( Figure 5C Layer 56-1 in FIG. 5 has the longest optical thickness and is advantageously used to promote TIR of light having the shallowest incident angles (e.g., 0 to 15°) compared to the other layers. To reduce the chance of light having greater incident angles (e.g., greater than 15°) being absorbed, additional layers having different optical thicknesses are provided (e.g., Figure 5B In some embodiments, the thickest layer (layer 56-1) is at least five times thicker than any other layer of the plurality of first dielectric layers (layers 56-3, 56-5, 56-7, 56-9, 56-11, and 56-13) and the plurality of second dielectric layers (layers 56-2, 56-4, 56-6, 56-8, 56-10, and 56-12). In some embodiments, the thinnest layer (layer 56-13) of the plurality of first dielectric layers is at least five times thicker than any other layer of the plurality of second dielectric layers (layers 56-2, 56-4, 56-6, 56-8, 56-10, and 56-12). Figure 5A The adhesive layer 64 or the second reflective layer 60 forms an interface.

[0091] In some embodiments, the average thickness of the plurality of first dielectric layers (layers 56-1, 56-3, 56-5, 56-7, 56-9, 56-11, and 56-13) is at least 2 times greater than the average thickness of the plurality of second dielectric layers (layers 56-2, 56-4, 56-6, 56-8, 56-10, and 56-12). In further embodiments, at least one layer of the plurality of second dielectric layers (layers 56-2, 56-4, 56-6, 56-8, 56-10, and 56-12) is at least 2 times thicker than the thinnest layer (56-13) of the plurality of first dielectric layers (layers 56-1, 56-3, 56-5, 56-7, 56-9, 56-11, and 56-13). In some embodiments, the plurality of first dielectric layers (layers 56-1, 56-3, 56-5, 56-7, 56-9, 56-11, and 56-13) include silicon dioxide, and the plurality of second dielectric layers (layers 56-2, 56-4, 56-6, 56-8, 56-10, and 56-12) include silicon nitride, and the thickness of layer 56-1 is 480 nm to 490 nm, the thickness of layer 56-2 is 80 nm to 90 nm, the thickness of layer 56-3 is 50 nm to 60 nm, and the thickness of layer 56-4 is 55 nm to 60 nm. The thickness of layer 56-5 is 65nm to 75nm, the thickness of layer 56-6 is 60nm to 70nm, the thickness of layer 56-7 is 65nm to 75nm, the thickness of layer 56-8 is 55nm to 65nm, the thickness of layer 56-9 is 50nm to 60nm, the thickness of layer 56-10 is 70nm to 80nm, the thickness of layer 56-11 is 80nm to 90nm, the thickness of layer 56-12 is 65nm to 75nm, and the thickness of layer 56-13 is 45nm to 55nm.

[0092] Figure 5D A cross-sectional view of the first reflective layer 56 according to other embodiments is shown. Figure 5D An embodiment similar to Figure 5C Therefore, Figure 5C The description also applies to Figure 5D , the differences are as follows.

[0093] exist Figure 5D The thickest layer is also shown as layer 56-1, which is Figure 5AThe active LED structure 52 forms an interface. The second thickest layer is shown as layer 56-3, and layers 56-1 and 56-3 are significantly thicker than any other layer of the first reflective layer 56. Therefore, layers 56-1 and 56-3 have the largest two optical thicknesses and promote TIR of light with shallower incident angles than other layers. The optical thickness of layer 56-3 is different from that of layer 56-1, and it weighs a certain shallow angle reflection to increase the reflection at a large angle, thereby helping to increase total reflection at all angles. In some embodiments, the thickest layer (layer 56-1) is at least 2 times thicker than the second thickest layer (layer 56-3) and at least 5 times thicker than any other layer of the plurality of first dielectric layers (layers 56-5, 56-7, 56-9, 56-11, and 56-13). Additionally, the thickest layer (layer 56-1) is at least 6 times thicker than any of the plurality of second dielectric layers (layers 56-2, 56-4, 56-6, 56-8, 56-10, and 56-12). Figure 5A The first reflective layer 56 is configured as follows Figure 5D As shown, layers 56-1 and 56-3 are closer to the active LED structure 52 than any other layer of the plurality of first dielectric layers (56-5, 56-7, 56-9, 56-11, and 56-13). Figure 5C Compared to the described embodiment, more light with shallow incident angles is reflected earlier. In turn, at least one other layer of the plurality of first dielectric layers (layers 56-5, 56-7, 56-9, 56-11, and 56-13) is much thinner than any other layer. Figure 5D , the thinnest layer is shown as layer 56-7, but it should be understood that in various embodiments, the thinnest layer can be any layer (layers 56-5, 56-7, 56-9, 56-11, and 56-13). In some embodiments, the thickest layer (layer 56-1) is at least 10 times thicker than the thinnest layer (layer 56-7) of the plurality of first dielectric layers, and in further embodiments, the thickest layer (layer 56-1) is at least 16 times thicker than the thinnest layer (layer 56-7). In addition, the thickest layer (layer 56-4) of the plurality of second dielectric layers is at least 2 times thicker than the thinnest layer (layer 56-7) of the plurality of first dielectric layers, and the thinnest layer (layer 56-6) of the plurality of second dielectric layers is at least 1.5 times thicker than the thinnest layer (layer 56-7).

[0094] In some embodiments, the plurality of first dielectric layers (layers 56-1, 56-3, 56-5, 56-7, 56-9, 56-11, and 56-13) include silicon dioxide, and the plurality of second dielectric layers (layers 56-2, 56-4, 56-6, 56-8, 56-10, and 56-12) include silicon nitride, and the thickness of layer 56-1 is 490 nm to 510 nm, the thickness of layer 56-2 is 60 nm to 70 nm, the thickness of layer 56-3 is 195 nm to 205 nm, and the thickness of layer 56-4 is 70 nm to 80 nm. The thickness of layer 56-5 is from 90nm to 100nm, the thickness of layer 56-6 is from 40nm to 50nm, the thickness of layer 56-7 is from 25nm to 35nm, the thickness of layer 56-8 is from 70nm to 80nm, the thickness of layer 56-9 is from 70nm to 80nm, the thickness of layer 56-10 is from 65nm to 75nm, the thickness of layer 56-11 is from 80nm to 90nm, the thickness of layer 56-12 is from 60nm to 70nm, and the thickness of layer 56-13 is from 55nm to 65nm.

[0095] Figure 5E A cross-sectional view of the first reflective layer 56 according to other embodiments is shown. Figure 5E An embodiment similar to Figure 5B Therefore, Figure 5B The description also applies to Figure 5E , the differences are as follows. Figure 5E In the embodiment, the first reflective layer 56 includes a plurality of dielectric layers (56-1, 56-2, 56-3, 56-4, 56-5) configured to provide a plurality of different interfaces therebetween. Figure 5A The interface of the active LED structure 52, and the layer 56-5 is formed with Figure 5A The first reflective layer 56 includes a plurality of first dielectric layers 56-1, 56-3, and 56-5 of a first material alternating with a plurality of second dielectric layers 56-2 and 56-4 of a second material different from the first material. The first material and the second material may be the same as those described above for Figure 5B The thickness of each of the plurality of first dielectric layers and each of the plurality of second dielectric layers may be as described above for Figure 5BAs described above. In some embodiments, a plurality of first dielectric layers 56-1, 56-3 and 56-5 include silicon dioxide, and a plurality of second dielectric layers 56-2 and 56-4 include silicon nitride. As previously described, silicon nitride can have a refractive index of about 1.9. Depending on the growth conditions and composition of the silicon nitride, the refractive index can include a range from about 1.8 to about 2.2. In some embodiments disclosed herein, a plurality of second dielectric layers 56-2 and 56-4 can include silicon nitride, which has been formed with growth conditions, such as a higher growth temperature or a different deposition rate, which is configured to provide a higher refractive index, for example, a refractive index in the range from about 2.0 to about 2.2. At this point, each interface between some of the first dielectric layers 56-1, 56-3 and 56-5 and some of the second dielectric layers 56-2 and 56-4 can have an increased refraction or reflection of light. Therefore, the total number of dielectric layers (56-1, 56-2, 56-3, 56-4, 56-5) can be reduced compared to the previous embodiments, for example, Figure 5E Five of them.

[0096] therefore, Figure 5A The first reflective layer 56 may include a plurality of dielectric layers. The plurality of dielectric layers may include embodiments in which each of the plurality of dielectric layers includes a different thickness. In some embodiments, the first reflective layer 56 includes 7 to 13 dielectric layers. In some embodiments, the first reflective layer 56 includes a plurality of alternating first and second dielectric layers. The first dielectric layer may have a different refractive index than the second dielectric layer. In some embodiments, the plurality of first dielectric layers include silicon dioxide and the plurality of second dielectric layers include silicon nitride, although other material combinations are possible as described above. In some embodiments, the first reflective layer 56 includes an odd number of first and second dielectric layers, while in other embodiments, the first reflective layer 56 includes an even number of first and second dielectric layers. In some embodiments, the first reflective layer 56 includes a non-periodic Bragg reflector. In some embodiments, the first reflective layer 56 includes a plurality of dielectric layers, wherein the thickest dielectric layer of the plurality of dielectric layers is separated from the active layer by at least one thinner dielectric layer. In other embodiments, the thickest dielectric layer is adjacent to the active LED structure, and in other embodiments, the second thickest dielectric layer is adjacent to the thickest dielectric layer compared to other layers of the plurality of first dielectric layers. In some embodiments, the first reflective layer 56 includes a plurality of first dielectric layers having an average thickness greater than the average thickness of the plurality of second dielectric layers, and at least one of the plurality of second dielectric layers has a thickness greater than the thickness of at least one of the plurality of first dielectric layers. In some embodiments, the thickest layer of the plurality of first dielectric layers is at least 10 times thicker than the thinnest layer of the plurality of first dielectric layers, and in further embodiments, the thickest layer of the plurality of first dielectric layers is at least 16 times thicker than the thinnest layer of the plurality of first dielectric layers.

[0097] Therefore, some embodiments disclosed herein include an LED chip, comprising: an active LED structure, including an active layer between an n-type layer and a p-type layer; and a first reflective layer, which is adjacent to the active LED structure and includes a plurality of first dielectric layers and a plurality of second dielectric layers, wherein an average thickness of the plurality of first dielectric layers is greater than an average thickness of the plurality of second dielectric layers, and wherein a thickness of at least one of the plurality of second dielectric layers is greater than a thickness of at least one of the plurality of first dielectric layers.

[0098] As described above, in some embodiments, the first reflective layer 56 includes a plurality of alternating first and second dielectric layers of varying materials having different refractive indices and thicknesses, which promote TIR over a wide range of incident angles. Therefore, the first reflective layer 56 can be referred to as a non-periodic Bragg reflector. In contrast, a periodic Bragg reflector is typically composed of multiple pairs of two materials having alternating higher and lower refractive indices. The thickness of each material is selected so that the reflected waves interfere constructively, and the thickness of each material remains constant in the repeated pairs. The periodic Bragg reflector provides improved reflectivity over a single dielectric reflector or a metal reflector, but the improved reflectivity is limited to a specific range of incident angles.

[0099] Fig. 6A 6 is a graph comparing the percent reflectivity over a wide range of wavelengths at zero degree angle of incidence for some embodiments. Each embodiment includes a first reflective layer and a second reflective layer on the active LED structure. Line 66 represents an embodiment in which the first reflective layer is a single dielectric layer of silicon dioxide and the second reflective layer is silver. Line 68 represents an embodiment in which the first reflective layer includes a plurality of first and second dielectric layers, the first and second dielectric layers including silicon dioxide and silicon nitride having the above-described compositions and thicknesses, and the second reflective layer is silver. Line 68 has significantly higher reflectivity at most wavelengths. For example, at some wavelengths above 450 nm, the reflectivity is at least 2% higher, and at some wavelengths between 500 nm and 530 nm, the reflectivity is about 5% higher.

[0100] Figure 6B and Figure 6C It is a heat map representation comparing the reflected intensity over a wide range of angles of incidence (AOI) and wavelengths. Fig. 6A Same, by Figure 6B and Figure 6C The embodiments shown all include a first reflective layer and a second reflective layer on the active LED structure. Figure 6B An embodiment is shown in which the first reflective layer comprises a plurality of first and second dielectric layers, the first and second dielectric layers comprising silicon dioxide and silicon nitride having the composition and thickness as described above, and the second reflective layer is silver, for example, Figure 5A LED chips with Figure 5DThe first reflective layer 56 is formed by a plurality of layers of a semiconductor device. Figure 6C An embodiment is shown in which the first reflective layer is a single dielectric layer of silicon dioxide and the second reflective layer is silver. It is worth noting that for zero angle of incidence, Fig. 6A The percent reflectivity improvements shown in are also achieved over a wide range of incident angles. For example, at most wavelengths from 400 nm to 650 nm, at most incident angles, Figure 6B Examples of Figure 6C The embodiment has a greater reflection intensity (indicated as darker areas).

[0101] Figure 7 is a graph showing the reflectivity percentage (%) of a sample including a first reflective layer and a second reflective layer on an active LED structure. The first reflective layer includes a plurality of first and second dielectric layers including silicon dioxide and silicon nitride having the composition and thickness as described above, and the second reflective layer is silver, for example, Figure 5A LED chips with Figure 5D The first reflective layer 56 is plotted for light having a wavelength of 460 nm at different incident angles (x-axis). The graph shows p-polarized reflectivity 70, s-polarized reflectivity 72, and average reflectivity 74, where average reflectivity 74 generally shows the total reflectivity of the first reflective layer for an LED that generates light with random polarization. It is noteworthy that when compared with Figure 4 When compared to a similar graph showing only a silver reflective layer on GaN, the reflectivity is significantly improved. For example, the average reflectivity 74 at zero degrees is at least 93% and exceeds 94% for most angles from about 15° to over 50°.

[0102] It should be understood that according to the present disclosure, the above-mentioned first reflective layer 56 arrangement can be used in many different LED chips. Fig. 8A Some embodiments of LED chips 80 are shown, which have a lateral geometry and are configured for flip chip mounting. LED chip 80 includes an active LED structure 82, which includes a p-type layer 84, an n-type layer 86, and an active layer 88 formed on a substrate 91. In some embodiments, the n-type layer 86 is between the active layer 88 and the substrate 91. In other embodiments, the p-type layer 84 is between the active layer 88 and the substrate 91. The substrate 91 can include many different materials, such as silicon carbide or sapphire, and can have one or more surfaces that are shaped, textured, or patterned to enhance light extraction.

[0103] The LED chip 80 further includes a current spreading layer 90 located between the active LED structure 82 and the first reflective layer 92. The current spreading layer 90 may have a Figure 5AThe current diffusion layer 90 has the same thickness as the current diffusion layer 54 shown and described above, and may include the same material. In the LED chip 80, the current diffusion layer 90 may include ITO and be located on the p-type layer 84 to diffuse the current into the p-type layer 84. The first reflective layer 92 is disposed on the current diffusion layer 90 and adjacent to the p-type layer 84, and may have any of the embodiments previously described for the first reflective layer 56 having multiple layers, such as Figure 5B As described. For example, in the LED chip 80, the first reflective layer 92 may include a plurality of dielectric layers. The plurality of dielectric layers may include embodiments in which each of the plurality of dielectric layers includes different thicknesses. In some embodiments, the first reflective layer 92 includes 7 to 13 dielectric layers. In some embodiments, the first reflective layer 92 includes a plurality of alternating first dielectric layers and a plurality of alternating second dielectric layers. The plurality of first dielectric layers may have a different refractive index from the plurality of second dielectric layers. In a further embodiment, the plurality of first dielectric layers include silicon dioxide and the plurality of second dielectric layers include silicon nitride, although other material combinations are possible as described above. In some embodiments, the first reflective layer 92 includes an odd number of first and second dielectric layers, while in other embodiments, the first reflective layer 92 includes an even number of first and second dielectric layers. In some embodiments, the first reflective layer 92 includes a non-periodic Bragg reflector. In some embodiments, the first reflective layer 92 includes a plurality of dielectric layers, wherein the thickest dielectric layer in the plurality of dielectric layers is separated from the active layer by at least one thinner dielectric layer. In some embodiments, the first reflective layer 92 includes a plurality of first dielectric layers having an average thickness greater than an average thickness of the plurality of second dielectric layers, and a thickness of at least one of the plurality of second dielectric layers is greater than a thickness of at least one of the plurality of first dielectric layers. Figure 5B ) also applies to the first reflective layer 92.

[0104] The second reflective layer 94 and the adhesive layer 96 are included on the first reflective layer 92, the adhesive layer 96 is sandwiched between the second reflective layer 94 and the first reflective layer 92, and provides adhesion between the second reflective layer 94 and the first reflective layer 92. These layers may include the same Figure 5A The second reflective layer 60 and the adhesive layer 64 are described as being of the same material and may have the same thickness. For example, in some embodiments, the second reflective layer 94 includes a conductive material, such as silver or other metals.

[0105] The LED chip 80 also includes a reflective layer hole 98, which can pass through the adhesive layer 96 and the first reflective layer 92 to the current spreading layer 90. Then, when the second reflective layer 94 is deposited, the hole 98 can be filled or partially filled. Therefore, the second reflective layer 94 is formed on the first reflective layer 92 and includes a through hole 100 to the current spreading layer 90. As described in more detail below, the second reflective layer 94 provides a conductive path through the first reflective layer 92 between the p-contact 110 and the current spreading layer 90 through the through hole 100. In some embodiments, the second reflective layer 94 completely fills the hole 98. In other embodiments, the second reflective layer 94 only partially fills the hole 98. When the second reflective layer 94 only partially fills the hole 98, the barrier layer 102 and the passivation layer 106 can fill the remaining portion of the through hole.

[0106] The hole 98 can be formed using many known processes, such as conventional etching processes or mechanical processes, such as micro-drilling. The hole 98 can have many different shapes and sizes. In the embodiment shown, the hole 98 has an angled or curved side surface and a circular cross-section with a diameter less than 20 μm. In some embodiments, the hole 98 can have a diameter of about 8 μm, while other holes have a diameter as low as 1 μm. Adjacent holes 98 can be less than 100 μm apart, and the embodiment shown has a spacing of 30 μm from edge to edge. In other embodiments, the hole 98 can have a spacing as small as 10 μm or less. It is understood that the hole 98 (and the resulting through hole 100) can have cross-sections of different shapes, such as square, rectangular, elliptical, hexagonal, and pentagonal. In other embodiments, the size and shape of the hole are inconsistent, and there can be different or inconsistent spaces between adjacent holes.

[0107] In other embodiments, different structures can be used to provide a conductive path between the p-contact 110 and the current spreading layer 90. Instead of the hole 98, an interconnected grid can be formed through the first reflective layer 92, and then a conductive material is deposited in the grid to form a conductive path to the current spreading layer 90. The grid can take many different forms, and in different embodiments, parts of the grid are interconnected at different angles. The electrical signal applied to the grid can spread throughout and propagate along the interconnected portions. It should also be understood that in different embodiments, the grid can be used in combination with holes, and other embodiments can provide other conductive paths. In some embodiments, one or more conductive paths can extend beyond the active layer of the LED chip, for example, along the side surface of the LED chip.

[0108] The LED chip 80 may also include a barrier layer 102 on the second reflective layer 94 to prevent the second reflective layer 94 material (e.g., silver) from migrating to other layers. Preventing such migration helps the LED chip 80 to maintain efficient operation throughout its lifetime. Therefore, the barrier layer 102 is also part of the conductive path from the p-contact 110 to the current spreading layer 90. In some embodiments, the barrier layer 102 is a single layer, while in other embodiments, the barrier layer 102 includes multiple layers. Suitable materials for the barrier layer 102 include, but are not limited to, sputtered Ti / Pt followed by evaporated Au bulk material or sputtered Ti / Ni followed by evaporated Ti / Au bulk material.

[0109] An active structure hole 104 may be included through the adhesion layer 96, the first reflective layer 92, and the p-type layer 84 to expose the n-type layer 86. A passivation layer 106 is included on the side surfaces of the barrier layer 102 and the active structure hole 104. The passivation layer 106 protects and provides electrical insulation between the contacts and the layers below, as described in more detail below. The passivation layer 106 may include many different materials, for example, a dielectric material. In some embodiments, the passivation layer 106 is a single layer, while in other embodiments, the passivation layer 106 includes multiple layers. Suitable materials for the passivation layer 106 include, but are not limited to, silicon nitride.

[0110] The passivation layer hole 108 may be formed through the passivation layer 106 to the barrier layer 102 and / or the second reflective layer 94. The p-contact 110 may then be deposited in the passivation layer hole 108. In operation, an electrical signal applied to the p-contact passes through the barrier layer 102, the second reflective layer 94, and the through hole 100, and reaches the current diffusion layer 90, through which the electrical signal diffuses to the p-type layer 84. Similarly, an n-contact 112 is formed on the passivation layer 106 and passes through the active structure hole 104, wherein the n-contact 112 provides an electrical path for the electrical signal to be applied to the n-type layer 86. In operation, the signal applied to the p-contact 110 and the n-contact 112 is conducted to the p-type layer 84 and the n-type layer 86, causing the LED chip 80 to emit light from its active layer 88.

[0111] The p-contact 110 and the n-contact 112 may include many different materials, such as Au, copper (Cu), nickel (Ni), In, Al, Ag, tin (Sn), Pt, or combinations thereof. In other embodiments, conductive oxides and transparent conductive oxides may be included, such as ITO, nickel oxide, zinc oxide, cadmium tin oxide, indium oxide, tin oxide, magnesium oxide, ZnGa2O4, ZnO2 / Sb, Ga2O3 / Sn, AgInO2 / Sn, In2O3 / Zn, CuAlO2, LaCuOS, CuGaO2, and SrCu2O2. The choice of material used depends on the location of the contacts and the desired electrical properties, such as transparency, junction resistivity, and sheet resistance.

[0112] As described above, the LED chip 80 is configured for flip chip mounting. In operation, the p-contact 110 and the n-contact 112 are bonded to a surface, such as a printed circuit board, via an electrical path for applying an electrical signal to the LED chip 80. In most cases, the p-contact 110 and the n-contact 112 are on the bottom surface, and light emitted toward the bottom of the LED chip is at risk of being at least partially absorbed, such as by the printed circuit board. The first reflective layer 92 and the second reflective layer 94 are disposed below the active layer 88 so that light emitted toward the bottom is reflected back to facilitate useful LED chip emission. The first reflective layer 92 reflects most of the light by TIR, and most of the remaining light is reflected by the second reflective layer 94.

[0113] Figure 8B Some embodiments of LED chips 113 are shown, which have a lateral geometry and are configured for flip chip mounting. LED chip 113 includes an active LED structure 82, which includes a p-type layer 84, an n-type layer 86, and an active layer 88 formed on a substrate 91 as previously described. Substrate 91 can include many different materials, such as silicon carbide or sapphire, and can include a patterned surface 105, which is shaped, textured, or patterned to enhance light extraction. As previously described, LED chip 113 also includes a first reflective layer 92, a second reflective layer 94, an adhesive layer 96, a reflective layer hole 98, a through hole 100 to current spreading layer 90, a barrier layer 102, an active structure hole 104 to n-type layer 86, a passivation layer 106, a passivation layer hole 108, a p-contact 110, and an n-contact 112. In some embodiments, passivation layer 106 includes a metal-containing intermediate layer 122 disposed therein, wherein intermediate layer 122 can include aluminum or another suitable metal. It is noteworthy that the intermediate layer 122 is embedded within the passivation layer 106 and is electrically insulated from the rest of the LED chip 113. In applications, the intermediate layer 122 can act as a crack stopper for any cracks that may propagate through the passivation layer 106. In addition, the intermediate layer 122 can reflect at least some of the light that may pass through the first reflective layer 92 and the second reflective layer 94. Figure 8B In the embodiment, the first reflective layer 92 is shown as a single layer; however, the first reflective layer 92 may include any multi-layer reflective combination as described above, for example, Figure 5B , Figure 5C , Figure 5D and Figure 5EIn some embodiments, the second reflective layer 94 includes a multi-layer reflective combination as described above for the first reflective layer 56 of the active LED structure 82. In addition, the first reflective layer 92 includes a portion proximate to the active LED structure 82 and a "surrounding" peripheral portion of the active LED structure 82 (including the n-type layer 86, the active layer 88, and the p-type layer 84). In this regard, the surrounding portion 92' of the first reflective layer 92 extends on the sidewalls of the p-type layer 84, the active layer 88, and the n-type layer 86, and extends laterally on a portion of the n-type layer 86 aligned with the active structure hole 104. Therefore, the peripheral portion of the LED active structure 82 has an improved reflectivity, and more light can be redirected to the substrate 91 and away from the LED chip 113. In some embodiments, the second reflective layer 94 does not include a surrounding portion extending along the sidewall of the active LED structure 82. For embodiments in which the second reflective layer 94 includes metal, the absence of the second reflective layer 94 on the sidewalls of the active LED structure 82 can reduce the migration of metal, which would otherwise contact the sidewalls of the p-type layer 84, the active layer 88, and the n-type layer 86, thereby causing an electrical short circuit.

[0114] As discussed above, the actual thickness of the layers may vary, and variations from the illustrated shapes are to be expected due to, for example, manufacturing techniques and / or tolerances. Regions illustrated or described as square or rectangular may have rounded or curved features, and regions shown as straight lines may have some irregularities. For example, Fig. 9A is a microscopic cross-sectional image of a portion of an LED chip according to some embodiments, which is close to Fig. 8A A single reflective layer hole 98. In particular, Fig. 9A is a focused ion beam image along a portion of the reflector hole 98. Fig. 9A , the active LED structure 82, the current spreading layer 90, the first reflective layer 92, the reflective layer hole 98, the second reflective layer 94, the barrier layer 102, and the passivation layer 106 are visible. As shown, the second reflective layer 94, the barrier layer 102, and the passivation layer 106 are located on the first reflective layer 92 and conform to the first reflective layer 92 through the hole. The second reflective layer 94 partially fills the reflective layer hole 98, and the remaining portion of the reflective layer hole 98 is filled by the barrier layer 102 and the passivation layer 106.

[0115] Fig. 9B is a cross-sectional view of a portion of an LED chip according to some embodiments, which is close to Figure 8B The active structure hole 104. Fig. 9B As shown in the figure, the n-contact 112 is configured to extend into the active structure hole 104 to provide an electrical connection with the n-type layer 86. As shown, the n-contact 112 is shown as two conformal layers, however, the n-contact 112 may include a multi-layer stack of conductive materials. For example, Fig. 9B The first and thinnest layer of the n-contact 112 shown may include an ohmic layer followed by one or more migration barrier layers, and Fig. 9B The thickest layer of the n-contact 112 shown may include one or more body contact layers. The ohmic layer may be conformally coated on the passivation layer 106 and directly coated on the surface of the n-type layer 86. The ohmic layer may include one or more layers of Al, chromium (Cr), Ti, ZnO, and Ag. The migration barrier layer may be conformally coated on the ohmic layer and may include one or more combinations of Ti, Au, Pt, Ni, titanium tungsten (TiW), and titanium nitride (TiN). The body contact layer may be conformally coated on the migration barrier layer and may include one or more combinations of gold tin (AuSn) and titanium nickel gold (TiNiAu). On the left side of the figure, the surrounding portion 92' ( Figure 8B The passivation layer 106 conformally covers the adhesion layer 96, the surrounding portion 92', and extends laterally along a portion of the n-type layer 86 between the surrounding portion 92' and the n-contact 112. Fig. 9C is a microscopic cross-sectional image of a portion of an LED chip according to some embodiments, which is close to Figure 8B A single reflective layer hole 98. In particular, Fig. 9C FIG. 1 is a cross-sectional view of a portion of an LED chip near a portion of the reflective layer hole 98. Fig. 9C As shown, the current spreading layer 90 is barely visible on the p-type layer 84. Portions of the first reflective layer 92 are visible on the left and right sides of the image, with the reflective layer hole 98 formed therebetween. The second reflective layer 94 extends over the first reflective layer 92 and along portions of the current spreading layer 90 aligned with the reflective layer hole 98. An adhesive layer 96 is disposed between portions of the first reflective layer 92 and the second reflective layer 94. The barrier layer 102, which may include a multilayer stack as previously described, is shown extending along the second reflective layer 94. The passivation layer 106 includes an intermediate layer 122, and the passivation layer 106 is configured to cover the barrier layer 102 over the entire reflective layer hole 98, thereby providing electrical insulation for the n-contact 112 extending along a portion of the passivation layer 106.

[0116] Therefore, some embodiments disclosed herein include an LED chip including an active LED structure, the active LED structure including an active layer between an n-type layer and a p-type layer; a first reflective layer, adjacent to the active LED structure and including a plurality of dielectric layers; a second reflective layer on the first reflective layer; a barrier layer on the second reflective layer; and a passivation layer on the barrier layer.

[0117] Fig. 10A shows a similar Fig. 8A and Figure 8B The LED chip 114 of the embodiment described. Fig. 10A, the LED chip 114 is in a flip chip orientation and includes an active LED structure 82, a substrate 91, a first reflective layer 92, a second reflective layer 94, a barrier layer 102, a passivation layer 106, a through hole 100, an active structure hole 104, a p-contact 110, and an n-contact 112, similar to Fig. 8A . The substrate 91 is light transmissive (preferably, transparent) and includes an outer major surface 118, a side surface 120, and an inner surface 116. The inner surface 116 is adjacent to the active LED structure 82 and includes a patterned surface 105 having a plurality of recessed and / or raised features adjacent to the active LED structure 82. In some embodiments, the patterned surface 105 is adjacent to the n-layer of the active LED structure 82. The patterned surface 105 is particularly useful in embodiments where the substrate 91 includes sapphire to facilitate extraction of light through the interface between the active LED structure 82 and the substrate 91. In some embodiments, the passivation layer 106 includes a metal-containing intermediate layer 122 disposed therein, wherein the intermediate layer 122 may include aluminum or another suitable metal. Notably, the intermediate layer 122 is embedded in the passivation layer 106 and is electrically insulated from the rest of the LED chip 114. In applications, the intermediate layer 122 may serve as a crack stopper for any cracks that may propagate through the passivation layer. Additionally, the intermediate layer 122 may reflect at least some of the light that may pass through the first reflective layer 92 and the second reflective layer 94 .

[0118] Fig. 10B The device is shown mounted on a substrate 124 and covered with at least one layer of luminescent material 126. Fig. 10A The substrate 124 includes a first contact pad 128 and a second contact pad 130 disposed adjacent to the p-contact 110 and the n-contact 112 of the LED chip 114, respectively. Solderless, flux, direct connection or other conventional connection methods may be used to establish conductive electrical communication between the first contact pad 128 and the p-contact 110 and the second contact pad 130 and the n-contact 112. Fig. 10B As shown, at least one luminescent material layer 126 is disposed to cover at least a portion of the outer major surface 118 , the side surface 120 , and the substrate 124 .

[0119] The luminescent materials described herein may be or include one or more of a phosphor, a scintillator, a luminescent ink, a quantum dot material, a fluorescent light strip, and the like. The luminescent material may be provided in any suitable manner, for example, directly coated on one or more surfaces of an LED, dispersed in an encapsulant material configured to cover one or more LEDs, and / or coated on one or more optical or supporting elements (e.g., by powder coating, inkjet printing, etc.). In some embodiments, the luminescent material may be down-converted or up-converted, and a combination of down-converted and up-converted materials may be provided. In some embodiments, a plurality of different (e.g., different compositions) luminescent materials configured to produce different peak wavelengths may be configured to receive emissions from one or more LED chips. In some embodiments, one or more phosphors may include a yellow phosphor (e.g., YAG:Ce), a green phosphor (LuAg:Ce), and a red phosphor (Ca:Ce). i-x-y Sr x Eu y AlSiN3) and combinations thereof.

[0120] One or more luminescent materials may be disposed on one or more portions of the flip chip LED and / or the substrate in various configurations. In some embodiments, one or more surfaces of the flip chip LED may be conformally coated with one or more luminescent materials, while other surfaces of such LED and / or the associated substrate may be free of luminescent materials. In some embodiments, the top surface of the flip chip LED may include luminescent materials, while one or more side surfaces of the flip chip LED may be free of luminescent materials. In some embodiments, all or substantially all external surfaces of the flip chip LED (e.g., except for contact-defining surfaces or mounting surfaces) are coated or covered with one or more luminescent materials. In some embodiments, one or more luminescent materials may be disposed on or above one or more surfaces of the flip chip LED in a substantially uniform manner; in other embodiments, one or more luminescent materials may be disposed on or above one or more surfaces of the flip chip LED in a non-uniform manner in one or more aspects of material composition, concentration, and thickness. In some embodiments, the loading percentage of one or more luminescent materials may vary on or in one or more external surfaces of the flip chip LED. In some embodiments, one or more luminescent materials may be patterned on portions of one or more surfaces of the flip chip LED to include one or more stripes, dots, curves, or polygons. In some embodiments, multiple luminescent materials can be disposed in different discrete regions or layers on or over a flip chip LED.

[0121] In some embodiments, the luminescent material may be disposed on a light-transmissive surface of the substrate, and the substrate may include a thickness of at least 120 μm, at least 150 μm, at least 170 μm, at least 200 μm, at least 230 μm, at least 250 μm (the aforementioned minimum thickness value is optionally limited at the upper end by any of the aforementioned thickness values), or another thickness threshold specified herein. Without wishing to be bound by any particular theory of operation, it is currently believed that providing a thicker substrate according to one or more of the aforementioned thickness thresholds can increase the conversion efficiency of the flip-chip LED converted by the luminophore, which is due to one or more of the following phenomena: (i) increasing the physical separation (distance) between the outer major (e.g., top) surface of the substrate and the multilayer reflector and (ii) reducing the light flux on the luminescent material disposed on or above the outer surface of the substrate.

[0122] The benefit of reduced optical losses may be more significant and pronounced for larger LED die sizes (e.g., substrate widths of at least about 1.2 mm, at least about 1.4 mm, at least about 2 mm, or greater). Larger dies have a greater reliance on internal reflectivity because light has more interactions with internal reflective layers before escaping the LED. The benefit of reduced light losses may also be more pronounced when creating warm white (vs. cool white) emitters because warm white emitters typically involve a greater amount of back reflections into the LED chip (e.g., due to conversion of multiple phosphor materials or material layers, such as a yellow layer and a red layer). As described above, the first reflective layer 92 includes improved reflectivity over a wide range of wavelengths and a wide range of incident angles, and is therefore additionally well suited for larger LED dies and / or having multiple LED dies that convert light from the active LED structure 82 into a variety of other colors. Furthermore, the first reflective layer 92 in combination with any or all of the second reflective layer 94, the intermediate layer 122, the patterned surface 105 and the light-transmissive or transparent substrate 91 reduces optical losses within the LED chip 114, thereby increasing brightness or luminous flux.

[0123] Fig.11A FIG. 1 shows an LED chip 132 according to another embodiment. Fig.11A , the active LED structure 82, substrate 91, first reflective layer 92, second reflective layer 94, barrier layer 102, passivation layer 106, through hole 100, active structure hole 104, p contact 110 and n contact 112 are similar to Fig. 10A In addition, the first reflective layer 92 and the second reflective layer 94 include a portion close to the active LED structure 82 and a "surrounding" peripheral portion of the active LED structure 82 (including the n-type layer, the active layer, and the p-type layer). Fig.11AAs shown, the active LED structure 82 extends away from the substrate 91 and forms a mesa 134 having a mesa sidewall 134', and the mesa sidewall 134' is laterally bounded by at least one groove 136 at the periphery of the LED chip 132. The at least one groove 136 includes a peripheral surrounding portion 92' of the first reflective layer 92, which defines a peripheral portion of the active LED structure 82 forming the mesa 134. In addition, the at least one groove 136 includes a peripheral surrounding portion 94' of the second reflective layer 94, which is disposed in contact with a portion of the surrounding portion 92' of the first reflective layer 92. Within the at least one groove 136, the surrounding portion 92' and the peripheral surrounding portion 94' are peripherally bounded by the passivation material of the passivation layer 106. Therefore, the active LED structure 82 includes a mesa sidewall 134', and the first reflective layer 92 extends along the mesa sidewall 134'.

[0124] As with the previous embodiment, the first reflective layer 92 may include a plurality of first and second dielectric layers having different materials, such as silicon dioxide and silicon nitride, and thus the surrounding portion 92' will also include silicon dioxide and silicon nitride. Thus, the peripheral portion of the LED active structure 82 has an improved reflectivity, and more light can be redirected to the substrate 91 and away from the LED chip 132. The presence of silicon nitride in the surrounding portion 92' of the first reflective layer 92 is used to provide passivation for the sides of the mesas 134 of the active LED structure 82. In particular, the presence of silicon nitride in the surrounding portion 92' can be used to protect the active LED structure 82 metal (e.g., silver) from migrating from the second reflective layer 94. Any metal that migrates along the edge of the mesas 134 may contact the n-layer and p-layer of the active LED structure 82 and provide an electrical short that may cause the LED chip 132 to fail in operation. In addition, the presence of silicon nitride in the passivation layer 106 within the groove 136 can be used to block potential paths for moisture to contact the metal-containing portion of the second reflective layer 94, which would result in a harmful chemical interaction. Therefore, it is desirable for the LED chip 132 to have improved lumen maintenance under all operating conditions, or less light loss over time.

[0125] Fig. 11B Shows Fig.11A The LED chip 132 is mounted on the substrate 124 and covered with a Fig. 10B The substrate 124 includes a first contact pad 128 and a second contact pad 130, which are disposed adjacent to the p-contact 110 and the n-contact 112, respectively. Solderless, flux, direct connection or other conventional connection methods may be used to establish conductive electrical communication between the first contact pad 128 and the p-contact 110 and the second contact pad 130 and the n-contact 112. Fig. 11BAs shown, at least one layer of luminescent material 126 is disposed to cover the outer major surface 118 of the substrate 91 and one or more side surfaces 120 of the substrate 91 and at least a portion of the base plate 124 .

[0126] Fig. 12A Another embodiment of an LED chip 138 according to the present invention is shown, which is flip-chip mounted on a base plate or substrate for use. The LED chip has many layers, similar to Fig. 8A , Fig. 10A and Fig. 10B The illustrated embodiment and those layers described above include an active LED structure 140 including a p-type layer 142, an n-type layer 144, and an active layer 146. A current spreading layer 148 is included on the p-type layer 142 to spread current to the p-type layer 142 during operation. A first reflective layer 150 is included on the current spreading layer 148, and a second reflective layer 152 is included on the first reflective layer 150 with a bonding layer 154 therebetween.

[0127] The first reflective layer 150 is disposed on the current diffusion layer 148 and adjacent to the p-type layer 142 and may have the same structure as previously described. Figure 5B The first reflective layer 56 or Fig. 8A The first reflective layer 92 may include any embodiment of the plurality of layers described. For example, in the LED chip 138, the first reflective layer 150 may include a plurality of dielectric layers. The plurality of dielectric layers may include embodiments in which each of the plurality of dielectric layers includes a different thickness. In some embodiments, the first reflective layer 150 includes 7 to 13 dielectric layers. In some embodiments, the first reflective layer 150 includes a plurality of alternating first and second dielectric layers. The plurality of first dielectric layers may have a different refractive index from the plurality of second dielectric layers. In a further embodiment, the plurality of first dielectric layers include silicon dioxide and the plurality of second dielectric layers include silicon nitride, although other material combinations are possible as described above. In some embodiments, the first reflective layer 150 includes an odd number of first and second dielectric layers, while in other embodiments, the first reflective layer 150 includes an even number of first and second dielectric layers. In some embodiments, the first reflective layer 150 includes a non-periodic Bragg reflector. In some embodiments, the first reflective layer 150 includes a plurality of dielectric layers, wherein the thickest dielectric layer in the plurality of dielectric layers is separated from the active layer by at least one thinner dielectric layer. In some embodiments, the first reflective layer 150 includes a plurality of first dielectric layers having an average thickness greater than an average thickness of the plurality of second dielectric layers, and a thickness of at least one of the plurality of second dielectric layers is greater than a thickness of at least one of the plurality of first dielectric layers. FIG. 5A to FIG. 5E The first reflective layer 56 and Fig. 8A and Figure 8BAll other embodiments described for the first reflective layer 92 are also applicable Fig. 12A The first reflective layer 150 is formed by a plurality of layers of a semiconductor device.

[0128] The LED chip 138 also includes a reflective layer hole 156, which can pass through the adhesive layer 154 and the first reflective layer 150 to the current spreading layer 148. Then, when the second reflective layer 152 is deposited, the reflective layer hole 156 can be filled or partially filled. Thus, the second reflective layer 152 is formed on the first reflective layer 150 and includes a through hole 158 to the current spreading layer 148, as previously described for Fig. 8A described.

[0129] exist Fig. 12A In the embodiment, the passivation layer 160 and the barrier layer 162 extend beyond the edge of the active LED structure 140, wherein the p-contact 164 can be formed on the barrier layer 162. It should be understood that the passivation layer 160 may include a metal intermediate layer, such as Fig. 10A As described in . An active structure hole 166 is included through the adhesive layer 154, the first reflective layer 150, the current diffusion layer 148, the p-type layer 142, and the active layer 146. The passivation layer 160 is included on the side surfaces of the barrier layer 162 and the active structure hole 166, and an n-contact through hole or an n-contact 168 is included in the active structure hole 166 for applying an electrical signal to the n-type layer 144. The electrical signal applied to the p-contact 164 is conducted to the p-type layer 142 through the barrier layer 162, the second reflective layer 152, and the current diffusion layer 148. Therefore, the electrical signal applied to the p-contact 164 and the n-contact 168 is conducted to the p-type layer 142 and the n-type layer 144, causing the active layer 146 to emit light.

[0130] exist Fig. 12A , the growth substrate for the LED chip 138 has been removed, and the top surface 170 of the n-type layer 144 is textured for light extraction. To provide mechanical stability, the LED chip 138 is flip-chip mounted on a substrate 172 with a bonding metal layer 174 and a cover mirror layer 176 between the substrate 172 and the active LED structure 140. Thus, the p-type layer 142 is located between the substrate 172 and the active layer 146. The substrate 172 can be made of many different materials, a suitable material is silicon. The cover mirror layer 176 can be made of many different materials, a suitable material is aluminum. The cover mirror layer 176 helps to reflect the reflected LED light that escapes the first reflective layer 150 and the second reflective layer 152, for example, light that can pass through the active structure hole 166. In some embodiments, the first reflective layer 150 can wrap around and extend on the sides of the active LED structure 140 within the active structure hole 166.

[0131] Fig. 12B The invention shows a structure covered with at least one layer of luminescent material 178. Fig. 12AThe LED chip 138. The luminescent material 178 may be directed to Fig. 10B At least one layer of luminescent material 126 is any material or combination of materials described above. Fig. 12B In the embodiment of the present invention, at least one luminescent material layer 178 can be deposited on top of the active LED structure 140 while exposing the p-contact 164. Fig. 12A In an embodiment of the present invention, the active LED structure 140 includes an n-type layer 144, an active layer 146, and a p-type layer 142. In some embodiments, at least one layer of luminescent material 178 is on the n-type layer 144. As described above, the first reflective layer 92 includes an improved reflectivity over a wide wavelength range and a wide incident angle range. In operation, light of various wavelengths is omnidirectionally emitted from the active layer 146 and / or omnidirectionally converted by at least one luminescent material layer 178, and can be reflected by the first reflective layer 150, the second reflective layer 152, or the cover mirror layer 176, and extracted from the textured top surface 170. Therefore, the first reflective layer 150, in combination with any one or all of the second reflective layer 152, the cover mirror layer 176, and the textured top surface 170, reduces optical losses within the LED chip 138, providing an increase in brightness or luminous flux.

[0132] In addition to the LED chip embodiments described above, the reflective layers described herein may also provide reflectivity improvements in other configurations. For example, Fig.13 is a cross-sectional view of a packaged LED 180 according to some embodiments. Fig.13 In the embodiment, at least one light source 182 (e.g., an LED chip) is mounted on a substrate 184. The substrate 184 may include any number of materials, including but not limited to alumina, AIN, silicon, and a printed circuit board. In some embodiments, a first reflective layer 186 is on the substrate 184 and between the at least one light source 182 and the substrate 184. In further embodiments, the first reflective layer 186 extends on the substrate 184 beyond at least the location where the light source 182 is mounted. In other embodiments, the first reflective layer 186 may be only on a portion of the substrate 184 outside of the area where the at least one light source 182 is mounted. The packaged LED 180 may also include a light emitting layer 188 and an encapsulant 190. The light emitting layer 188 may include any of the light emitting materials described previously, such as, for example, Fig. 10A As described, the sealant 190 may include a light-transmitting material that can be molded into a lens shape, such as silicone or glass. In some embodiments, the light-emitting layer 188 is on the first reflective layer 186 outside the at least one light source 182. In some embodiments, the light-emitting layer 188 and the sealant 190 may be combined, such as a silicone material used as a binder for the light-emitting material. The first reflective layer 186 may be any multi-layer reflective combination as described above, for example, for Figure 5B , Figure 5C , Figure 5Dand Figure 5E As described above, the first reflective layer 186 is located in the optical path of the at least one light source 182. For example, the light emitted by the at least one light source 182 and the light converted by the light emitting layer 188 toward the substrate 184 can be reflected by the first reflective layer 186 at a position between the at least one light source 182 and the substrate 184 and at a position on the substrate 184 other than the position where the at least one light source 182 is installed.

[0133] Fig.14 is a cross-sectional view of a packaged LED 192 according to some embodiments, which is similar to Fig.13 180, but multiple light sources 194, such as LED chips, are shown. It is worth noting that the first reflective layer 195 is located on the substrate 196 and is located in the light path of the multiple light sources 194, and is configured to reflect the light emitted by the multiple light sources 194. The first reflective layer 195 can be any multi-layer reflective combination as described above, for example, Figure 5B , Figure 5C , Figure 5D and Figure 5E The multi-layer reflective combination of the first reflective layer 56 of the embodiment of the present invention. The sealant 198 can be disposed on the plurality of LED chips 194 and can include many shapes, such as but not limited to a square or rectangular cube shape, a hemispherical lens, or a hemispherical lens with a flat side surface. In some embodiments, the sealant can be dispensed on the substrate 196 inside the retaining material (not shown) surrounding the plurality of light sources 194.

[0134] Fig.15 2 is a cross-sectional view of a multi-junction LED chip 200 according to some embodiments. The multi-junction LED chip 200 includes a substrate 204, at least one n-type layer 206, at least one active layer 208, and at least one p-type layer 210. The individual junctions 218 are provided by isolation trenches 216 extending through the at least one p-type layer 210 and the at least one active layer 208 to the at least one n-type layer 206. In some embodiments, the isolation trenches 216 extend to the substrate 204. In some embodiments, the isolation trenches 216 extend completely through the substrate 204, such as Fig.15, as shown by the vertical dashed lines in . In embodiments where the substrate 204 is removed, the isolation trench 216 can extend through at least one n-type layer 206. For each individual junction 218, the individual junction 218 can be individually addressable via an individual first contact 212 and an individual second contact 214. For example, the multi-junction LED chip 200 can be mounted on a substrate (not shown) that includes corresponding electrical connections for the first contact 212 and the second contact 214. The substrate can be a printed circuit board with electrical traces or any other type of substrate with corresponding electrical connections. The multi-junction LED chip 200 also includes a first reflective layer 202 that can be on at least one p-type layer 210 of the individual junction 218. The first reflective layer 202 can be any multi-layer reflective combination as described above, for example, for Figure 5B , Figure 5C , Figure 5D and Figure 5E The first reflective layer 202 is located in the optical path of the multi-junction LED chip 200. The multi-junction LED chip 200 may be similar to the multi-junction LED chip 200 previously described. Fig. 8A , Fig. 10A , Fig. 10B , Fig.11A and Fig. 11B In other embodiments, the multi-junction LED chip 200 can be similar to the flip-chip LED previously described for Fig. 12A and Fig. 12B The first reflective layer 202 may be on each individual junction 218, and the isolation trench 216 may extend through the first reflective layer. In other embodiments, the first reflective layer 202 may be a continuous layer across all individual junctions 218, such as Fig.15 For example, the isolation trench 216 may be formed from the substrate or the at least one n-type layer 206 toward but not through the first reflective layer 202 .

[0135] In other embodiments, the reflective layers described herein may also provide reflectivity improvements in system-level configurations. For example, Fig.16 is a cross-sectional representation of a portion of lighting fixture 220 according to some embodiments. Fig.16In the figure, the lighting fixture 220 includes a light source 222. The light source 222 can be a single light source or a plurality of light sources, and can include packaged LEDs, semiconductor-based LED chips, organic LED chips, lasers, fluorescent light sources, and incandescent light sources, among others. The light source 222 is mounted or supported on a housing 224 of the lighting fixture 220. A first reflective layer 226 is located on the housing, and can be located between the light source 222 and the housing 224 and at a location other than where the light source 222 is supported by the housing 224. In some embodiments, the first reflective layer 226 is located only at a location other than where the light source 222 is supported by the housing 224. The first reflective layer 226 can be any multi-layer reflective combination as described above, for example, for Figure 5B , Figure 5C , Figure 5D and Figure 5E The multi-layer reflective combination described by the first reflective layer 56 of the housing 224. The lighting fixture 220 can also include a light-transmissive cover 228. Therefore, the first reflective layer 226 is located in the light path of the light source 222. For example, light emitted by the light source 222 can be reflected by the first reflective layer 226 on the housing 224 before leaving the lighting fixture 220 through the light-transmissive cover 228.

[0136] Therefore, some embodiments described herein include a device including a light source and a first reflective layer located in the light path of the light source. The first reflective layer includes a plurality of first dielectric layers and a plurality of second dielectric layers, and the average thickness of the plurality of first dielectric layers is greater than the average thickness of the plurality of second dielectric layers. The thickness of at least one of the plurality of second dielectric layers is greater than the thickness of at least one of the plurality of first dielectric layers. In addition, the reflective layer may include the above-mentioned Figure 5B , Figure 5C , Figure 5D and Figure 5E Any of the embodiments described herein. Other embodiments described herein include a device including a light source and a first reflective layer located in an optical path of the light source. The first reflective layer includes a plurality of first dielectric layers and a plurality of second dielectric layers, wherein each of the plurality of first dielectric layers includes a different thickness. The thickest layer of the plurality of first dielectric layers is located between the other layers of the plurality of first dielectric layers. In addition, the reflective layer may include the above embodiment for Figure 5B , Figure 5C , Figure 5D and Figure 5E Any embodiment described.

[0137] As mentioned above, an adhesive layer can be disposed between the first reflective layer and the second reflective layer to promote adhesion between the two. Many different materials can be used for the adhesive layer, for example, titanium oxide (TiO, TiO2), titanium oxynitride (TiON, Ti x O yN), tantalum oxide (TaO, Ta2O5), tantalum oxynitride (TaON), aluminum oxide (AlO, Al x O y ) or a combination thereof. In some embodiments, it may be desirable to form an adhesive layer having a smooth surface on which the second reflective layer may be formed. If the adhesive layer includes a surface having a rough surface morphology, undesirable light scattering sites may be introduced between the adhesive layer and the second reflective layer. In addition, the rough surface morphology may negatively affect the film quality of subsequently formed layers. In some embodiments, the adhesive layer includes aluminum oxide, such as Al x O y or Al2O3, which can be formed by electron beam deposition to provide a dense and continuous film with a smooth surface and no significant surface morphology. In this regard, the thickness of about The Al2O3 film was observed using a scanning electron microscope. Fig.17A This is a scanning electron microscope image of the Al2O3 film surface at a magnification of about 10,000 times. As shown in the figure, there is no obvious surface morphology in the Al2O3 film at 10,000 times. Fig. 17B It is magnified about 50,000 times. Fig.17A Scanning electron microscope image of the Al2O3 film surface at 50,000 times. Likewise, no surface morphology is clearly visible in the Al2O3 film at 50,000 times. In this regard, the bonding layer including Al2O3 formed by electron beam deposition can form a smooth surface on which the second reflective layer can be formed. Therefore, the interface between the bonding layer and the second reflective layer can have reduced scattering points and improved layer quality.

[0138] In certain embodiments, it may be desirable to form an interface between the bonding layer and the second reflective layer having a controlled morphology or grain structure. For example, a pattern or array of full or partial openings within the bonding layer may provide improved bonding between the second reflective layer and the first reflective layer while reducing optical losses. In this regard, Fig.18A is a cross-sectional view of an adhesive layer 96 having a controlled morphology or grain structure between a first reflective layer 92 and a second reflective layer 94. The first reflective layer 92 and the second reflective layer 94 can be configured as previously described. As shown, the adhesive layer 96 is configured to form a plurality of openings 96' extending between the first reflective layer 92 and the second reflective layer 94. In particular, one or more openings of the plurality of openings 96' extend through the entire thickness of the adhesive layer 96. In some embodiments, as previously described, the adhesive layer 96 includes aluminum oxide, such as Al x O y In a further embodiment, the bonding layer 96 comprises anodized aluminum (Al x O yIn order to form the adhesion layer 96 with anodized aluminum, an aluminum layer may first be formed or deposited on the first reflective layer 92. The aluminum layer may then be anodized with an electrolyte. During the anodization process, the electrochemical conversion of the aluminum film to anodized aluminum may form pores, nanopores, or openings 96' in the anodized aluminum film. Fig.18A , the bonding layer 96 includes a first surface 230 that contacts the first reflective layer 92. In some embodiments, the bonding layer 96 includes anodized aluminum that forms holes, nanoholes, or openings 96' that extend completely between the first reflective layer 92 and the second reflective layer 94. In other embodiments, the bonding layer 96 may include other anodic metal oxides. One or more of the plurality of openings 96' may be at least partially filled with the second reflective layer 94. In this regard, a portion of the second reflective layer 94 may completely fill one or more of the plurality of openings 96' and the contact portion of the first reflective layer 92. Therefore, the surface area between the second reflective layer 94 and the bonding layer 96 is increased, which may promote improved adhesion. In addition, at least some of the light that passes through the first reflective layer 92 may be reflected by the second reflective layer 94 without passing through the bonding layer 96, which may reduce some optical losses. In other embodiments, the second reflective layer 94 may only partially fill the opening 96', while in other embodiments, the second reflective layer 94 may not fill the opening 96'. Fig.18B The first reflective layer 92 is removed. Fig.18A A bottom view of the first surface 230 of the adhesive layer 96. Fig.18B As shown, the openings 96' of the bonding layer 96 can form a pattern or array on the bonding layer 96. As previously described, the openings 96' can extend completely through the bonding layer 96 so that portions of the second reflective layer 94 are visible.

[0139] Fig.19A is a cross-sectional view of an adhesive layer 96 having a different controlled morphology or grain structure between a first reflective layer 92 and a second reflective layer 94. Fig.19A As shown, the plurality of openings 96' extend through less than the entire thickness of the bonding layer 96 between the second reflective layer 94 and the first reflective layer 92. In particular, the plurality of openings 96' extend from the second reflective layer 94 toward the first reflective layer 92. To reiterate, the plurality of openings 96' extend through the boundary between the second reflective layer 94 and the bonding layer 96, but do not extend through the boundary between the bonding layer 96 and the first reflective layer 94. In this regard, the first surface 230 of the bonding layer 96 can form a continuous interface with the first reflective layer 92. As previously described, the bonding layer 96 can include an anodic metal oxide, such as an anodic aluminum oxide. In order to form Fig.19AThe illustrated bonding layer 96 stops the anodization process before the pores, nanopores, or openings 96' are able to extend completely through the bonding layer 96. In this manner, the surface area between the interface between the second reflective layer 94 and the bonding layer 96 can be increased while maintaining continuous contact between the bonding layer 96 and the first reflective layer 92. Fig.19B The first reflective layer 92 is removed. Fig.19A A bottom view of the first surface 230 of the adhesive layer 96. Fig.19B As shown, the first surface 230 of the adhesive layer 96 is continuous, and Fig.19A The opening 96' is not visible.

[0140] like FIG. 18A to FIG. 19B As shown, forming the bonding layer 96 with an anodized metal oxide provides the ability to customize the refractive index of the bonding layer 96. In particular, changing the electrochemical conditions of the anodizing process, such as one or more of the electrolyte concentration, acidity, solution temperature, current, and anodizing time, can change the width of the opening 96'. Different widths of the opening 96' can provide a film with different refractive indices. In particular, a larger width of the opening 96' can increase the refractive index of the bonding layer 96, while a smaller width of the opening 96' can reduce the refractive index of the bonding layer 96. For example, in the case where the bonding layer 96 includes anodized aluminum (Al x O y In embodiments where the substrate is Al 2 O 3 , the width of the customized opening 96 ′ can provide a refractive index of the bonding layer 96 in a range of about 1.4 to about 2.1.

[0141] As mentioned earlier, the aluminum oxide film has a lower extinction coefficient for wavelengths around 450nm, so it absorbs less light generated by the active LED structure. Fig. 20 is a plot showing ellipsometry of an Al2O3 film. For the measurement, a film with a thickness of approximately Al2O3 film. ψ and δ data were collected and plotted at angles of 55°, 65°, and 75° over the wavelength range represented by the x-axis. Fig. 20 Model analysis of the ellipsometric data plotted in calculates a refractive index of approximately 1.7 and an extinction coefficient of less than approximately 0.001, demonstrating that the bonding layer comprising aluminum oxide reduces absorption of light generated by the active LED structure.

[0142] Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered to be within the scope of the concepts disclosed herein and the appended claims.

Claims

1. A light emitting diode (LED) chip, comprising: an active LED structure including an active layer between an n-type layer and a p-type layer; as well as a first reflective layer adjacent to the active LED structure and comprising a plurality of first dielectric layers and a plurality of second dielectric layers, wherein each of the plurality of first dielectric layers comprises a different thickness; The thickest layer among the plurality of first dielectric layers is located between other layers of the plurality of first dielectric layers.

2. The LED chip according to claim 1, wherein: The first reflective layer includes an odd number of the plurality of first dielectric layers compared to the number of the plurality of second dielectric layers. The LED chip according to claim 1 , further comprising a second reflective layer on the first reflective layer.

4. The LED chip according to claim 3, wherein: The second reflective layer includes an electrical path passing through the first reflective layer. 5 . The LED chip according to claim 1 , further comprising a current spreading layer between the active LED structure and the first reflective layer.

6. The LED chip according to claim 5, wherein: The current spreading layer includes indium tin oxide. 7 . The LED chip according to claim 3 , further comprising an adhesive layer between the first reflective layer and the second reflective layer.

8. The LED chip according to claim 7, wherein: The adhesion layer includes a metal oxide.

9. The LED chip according to claim 7, wherein: The bonding layer includes aluminum oxide.

10. The LED chip according to claim 1, wherein: The first reflective layer is adjacent to the p-type layer.

11. The LED chip according to claim 1, wherein: The active LED structure includes a mesa sidewall, and the first reflective layer extends along the mesa sidewall.

12. A light emitting diode (LED) chip, comprising: an active LED structure including an active layer between an n-type layer and a p-type layer; as well as a first reflective layer, adjacent to the active LED structure, and comprising a plurality of first dielectric layers and a plurality of second dielectric layers; wherein an average thickness of the plurality of first dielectric layers is greater than an average thickness of the plurality of second dielectric layers; and The thickness of at least one of the plurality of second dielectric layers is greater than the thickness of at least one of the plurality of first dielectric layers.

13. The LED chip according to claim 12, wherein: An average thickness of the plurality of first dielectric layers is at least 2 times greater than an average thickness of the plurality of second dielectric layers.

14. The LED chip according to claim 12, wherein: An average thickness of the plurality of first dielectric layers is at least 3 times greater than an average thickness of the plurality of second dielectric layers.

15. The LED chip according to claim 12, wherein: The thickest layer of the plurality of first dielectric layers is adjacent to the active LED structure.

16. The LED chip according to claim 12, wherein: The thickest layer of the plurality of first dielectric layers is at least 10 times thicker than the thinnest layer of the plurality of first dielectric layers.

17. The LED chip according to claim 12, wherein: A second thickest layer among the plurality of first dielectric layers is adjacent to the thickest layer among the plurality of first dielectric layers.

18. The LED chip according to claim 12, wherein: The plurality of first dielectric layers include silicon dioxide.

19. The LED chip according to claim 12, wherein: The plurality of second dielectric layers include silicon nitride.

20. The LED chip according to claim 12, further comprising: a current spreading layer between the active LED structure and the first reflective layer; as well as A second reflective layer, wherein the second reflective layer includes an electrical path through the first reflective layer to the current spreading layer.

21. An apparatus comprising: light source; as well as a first reflective layer in the light path of the light source; Wherein, the first reflective layer includes a plurality of first dielectric layers and a plurality of second dielectric layers; wherein an average thickness of the plurality of first dielectric layers is greater than an average thickness of the plurality of second dielectric layers; and The thickness of at least one of the plurality of second dielectric layers is greater than the thickness of at least one of the plurality of first dielectric layers.

22. The apparatus according to claim 21, further comprising: substrate; The light source includes at least one LED chip mounted on the substrate, and the first reflective layer is located between the at least one LED chip and the substrate.

23. The device according to claim 22, wherein: The at least one LED chip includes a plurality of LED chips.

24. The device according to claim 21, wherein The light source includes a monolithic multi-junction LED chip.

25. The apparatus of claim 21, further comprising: shell; Wherein, the light source comprises at least one packaged LED mounted on the housing, and the first reflective layer is on the housing.

26. An apparatus comprising: light source; as well as a first reflective layer in the light path of the light source; wherein the first reflective layer comprises a plurality of first dielectric layers and a plurality of second dielectric layers, wherein each of the plurality of first dielectric layers comprises a different thickness; and The thickest layer among the plurality of first dielectric layers is located between other layers of the plurality of first dielectric layers.

27. A light emitting diode (LED) chip, comprising: an active LED structure including an active layer between an n-type layer and a p-type layer; a first reflective layer, adjacent to the active LED structure, and comprising a plurality of dielectric layers; a second reflecting layer on the first reflecting layer; as well as An adhesive layer between the first reflective layer and the second reflective layer, wherein the adhesive layer comprises a metal oxide.

28. The LED chip according to claim 27, wherein: The metal oxide includes aluminum oxide.

29. The LED chip according to claim 28, wherein: The aluminum oxide includes Al x O y , where 1≤x≤4 and 1≤y≤6.

30. The LED chip according to claim 28, wherein: The aluminum oxide includes Al x O y , where x=2 and y=3.

31. The LED chip according to claim 27, wherein: The metal oxide includes an anode metal oxide.

32. The LED chip according to claim 31, wherein: The anodic metal oxide includes anodized aluminum oxide.

33. The LED chip according to claim 27, wherein: The thickness of the bonding layer is in the range of about 60 angstroms to about 150 angstroms.

34. The LED chip according to claim 27, wherein: The thickness of the adhesive layer is in a range of about 90 angstroms to about 120 angstroms.

35. The LED chip according to claim 27, wherein: Each dielectric layer of the plurality of dielectric layers comprises a different thickness.

36. The LED chip according to claim 27, wherein: The plurality of dielectric layers includes 5 to 13 dielectric layers.

37. The LED chip according to claim 27, wherein: The plurality of dielectric layers includes non-periodic Bragg reflectors.

38. The LED chip according to claim 27, wherein: The thickest dielectric layer of the plurality of dielectric layers is separated from the active LED structure by at least one thinner dielectric layer.

39. The LED chip according to claim 27, wherein: The plurality of dielectric layers includes alternating first dielectric layers and second dielectric layers.

40. The LED chip according to claim 39, wherein: The first dielectric layer includes silicon dioxide, and the second dielectric layer includes silicon nitride.

41. The LED chip according to claim 40, wherein: The silicon nitride includes a refractive index within a range from about 1.8 to about 2.

2.

42. The LED chip according to claim 40, wherein: The silicon nitride includes a refractive index within a range from about 2.0 to about 2.

2.

43. A light emitting diode (LED) chip, comprising: an active LED structure including an active layer between an n-type layer and a p-type layer; a first reflective layer, adjacent to the active LED structure; a second reflecting layer on the first reflecting layer; as well as An adhesive layer between the first reflective layer and the second reflective layer, wherein the adhesive layer comprises an anodic metal oxide.

44. The LED chip according to claim 43, wherein: The anodic metal oxide includes anodized aluminum oxide.

45. The LED chip according to claim 44, wherein: The anodized aluminum has a refractive index in a range from about 1.4 to about 2.

1.

46. ​​The LED chip according to claim 43, wherein: The adhesive layer forms a plurality of openings extending through the entire thickness of the adhesive layer.

47. The LED chip according to claim 46, wherein: One or more openings of the plurality of openings are at least partially filled with the second reflective layer.

48. The LED chip according to claim 43, wherein: The adhesive layer forms a plurality of openings extending through less than the entire thickness of the adhesive layer.

49. The LED chip according to claim 48, wherein: The plurality of openings extend from the second reflective layer toward the first reflective layer.

50. The LED chip according to claim 43, wherein: The thickness of the bonding layer is in the range of about 60 angstroms to about 150 angstroms.

Images