Dbr structure, light emitting diode, and light emitting device

Abstract

The application provides a DBR structure, a light emitting diode and a light emitting device. The DBR structure comprises a first part, a second part and a third part in sequence. The first part comprises a plurality of first material layers with an optical thickness greater than 0.1 lambda and at least one first material layer with an optical thickness less than 0.05 lambda. The optical thickness of the first material layers in the second part is between 0.3 lambda and 0.45 lambda. The optical thickness of the first material layers in the third part is between 0.3 lambda and 0.45 lambda, and the difference of the optical thickness of the first material layers in the third part is greater than that in the second part. The module design provided by the application can effectively resist the problem of large-angle light transmission weakening caused by wavelength change, promote different wavebands of light to be emitted from the side and back of the light emitting diode, and the DBR structure can always maintain stable and uniform transmittance with the change of the incident angle, thereby increasing the brightness of the chip and improving the uniformity of light emission.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a DBR structure, a light emitting diode and a light emitting device. BACKGROUND

[0002] A light emitting diode (LED) is a kind of semiconductor device, and its basic structure includes a PN junction between a P-type semiconductor and an N-type semiconductor. When a forward voltage is applied to the LED, electrons and holes recombine at the junction of the PN junction and release energy in the form of photons, which form light radiation.

[0003] In a Mini backlight product, a large-angle Mini LED is more likely to achieve panel uniformity due to its large light-emitting angle. Compared with a traditional LED chip, a large-angle Mini LED is arranged more sparsely at the backlight application end and does not need an additional lens for secondary light distribution, greatly reducing production costs.

[0004] In order to ensure large-angle light emission of the chip, the prior art mainly relies on evaporation of a distributed Bragg reflector (DBR) on the light-emitting surface of the LED chip. This structure can guide large-angle light to pass through and reflect small-angle light, effectively promoting light emission from the side and back, so as to increase the light-emitting angle. However, the existing scheme has a significant technical bottleneck: the wavelength band in which the LED chip can maintain good large-angle light emission is limited. As the wavelength changes, the transmission of large-angle light by the LED chip decreases, resulting in reduced chip brightness. Therefore, it is necessary to provide a technical solution to solve or improve the above-mentioned difficult problems. SUMMARY

[0005] In view of the defects and deficiencies of the prior art large-angle LED chip described above, the purpose of the present application is to provide a DBR structure, a light emitting diode and a light emitting device to effectively resist the weakening of large-angle light transmission caused by wavelength change and increase the brightness of the chip.

[0006] In order to achieve the above-mentioned purpose and other related purposes, the present application provides a distributed Bragg reflector structure, which at least includes first material layers and second material layers stacked alternately, the refractive index of the first material layer is less than the refractive index of the second material layer; along the thickness direction of the distributed Bragg reflector structure, the distributed Bragg reflector structure includes in sequence:

[0007] The first part includes a plurality of first material layers and a plurality of second material layers, wherein the first material layers include a plurality of first material layers with an optical thickness greater than 0.1λ, and at least one first material layer with an optical thickness less than 0.05λ;

[0008] The second part includes multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ.

[0009] The third part includes multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ, and the difference in optical thickness of the first material layers in the third part is greater than the difference in optical thickness of the first material layers in the second part.

[0010] According to one aspect of this application, a distributed Bragg reflection structure is also provided, comprising at least alternatingly stacked first and second material layers, wherein the refractive index of the first material layer is less than the refractive index of the second material layer; along the thickness direction of the distributed Bragg reflection structure, the distributed Bragg reflection structure sequentially comprises:

[0011] The first part includes multiple first material layers and multiple second material layers, wherein the first material layer includes at least one first material layer with an optical thickness of less than 0.1λ, and the second material layer includes at least one second material layer with an optical thickness of less than 0.1λ.

[0012] The second part includes multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ.

[0013] The third part includes multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ, and the second material layers include at least one second material layer with an optical thickness of less than 0.1λ.

[0014] According to one aspect of this application, a distributed Bragg reflection structure is also provided, comprising at least alternating stacked first material layers and second material layers, wherein the refractive index of the first material layer is less than the refractive index of the second material layer; wherein the first material layer comprises at least one first material layer whose optical thickness is less than the optical thickness of any second material layer.

[0015] According to one aspect of this application, a distributed Bragg reflection structure is also provided, comprising at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than the refractive index of the second material layer; wherein...

[0016] The first material layer includes several film layers with an optical thickness greater than 0.35λ and at least one film layer with an optical thickness less than 0.1λ, and the optical thickness of the second material layer is less than 0.2λ. In the incident angle range of 30° to 60°, the transmittance of the distributed Bragg reflection structure to light is greater than or equal to 90%.

[0017] According to one aspect of this application, a light-emitting diode is also provided, comprising at least:

[0018] A substrate having opposing first and second surfaces;

[0019] An epitaxial structure is formed on a first surface of the substrate, the epitaxial structure comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked sequentially.

[0020] A distributed Bragg reflection structure is located on a second surface of a substrate. The distributed Bragg reflection structure includes at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than that of the second material layer. Along the thickness direction of the distributed Bragg reflection structure, the distributed Bragg reflection structure sequentially includes: a first part comprising a plurality of first material layers with an optical thickness greater than 0.15λ and at least one first material layer with an optical thickness less than 0.1λ; a second part, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ; and a third part, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ, and the difference in optical thickness of the first material layers in the third part is greater than the difference in optical thickness of the first material layers in the second part.

[0021] According to one aspect of this application, a light-emitting diode is also provided, comprising at least:

[0022] A substrate having opposing first and second surfaces;

[0023] An epitaxial structure is formed on a first surface of the substrate, the epitaxial structure comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked sequentially.

[0024] A distributed Bragg reflection structure is located on the second surface of the substrate. The distributed Bragg reflection structure includes at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than that of the second material layer; wherein the first material layer includes a plurality of film layers with an optical thickness greater than 0.35λ and at least one film layer with an optical thickness less than 0.05λ, and the optical thickness of the second material layer is less than 0.2λ; within an incident angle range of 30° to 60°, the transmittance of the distributed Bragg reflection structure is greater than or equal to 90%.

[0025] According to one aspect of this application, a light-emitting device is also provided, the light-emitting device comprising:

[0026] Packaging substrate;

[0027] At least one light-emitting diode is disposed on the surface of the packaging substrate, and the packaging substrate and the electrode structure of the light-emitting diode are electrically connected; the light-emitting diode is any one of the light-emitting diodes described in the above technical solutions.

[0028] This application optimizes the optical thickness of a distributed Bragg reflector (DBR) structure module. The DBR structure comprises: a first part, including several first material layers with an optical thickness greater than 0.1λ and at least one first material layer with an optical thickness less than 0.05λ; a second part, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ; and a third part, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ, and the difference in optical thickness of the first material layers in the third part is greater than the difference in optical thickness of the first material layers in the second part. This module design effectively resists the problem of reduced light transmission at large angles caused by wavelength changes, promoting the emission of light from the sides and back of the LED across different wavelengths, thereby increasing chip brightness and improving light uniformity. Within an incident angle range of 30° to 60°, the transmittance of this DBR structure is greater than or equal to 90%, and within this incident angle range, the DBR structure maintains a stable and uniform transmittance regardless of the change in the incident angle.

[0029] In addition, the light-emitting device provided in this application includes the DBR structure and light-emitting diode provided in the above technical solution. Therefore, the light-emitting device also has the above-mentioned good technical effects. Attached Figure Description

[0030] Figure 1 This is a schematic diagram illustrating the light reflection principle of large-angle LED chips in existing technology.

[0031] Figure 2 This is a schematic diagram of the structure of the light-emitting diode provided in this application;

[0032] Figure 3 A schematic diagram of the distributed Bragg reflection structure provided in this application;

[0033] Figure 4 A schematic diagram of the membrane system composition of the distributed Bragg reflector structure provided in this application;

[0034] Figure 5 The reflectivity of the distributed Bragg reflector structure provided in this application varies with the incident angle.

[0035] Figure 6 This is a schematic diagram of the structure of the light-emitting device provided in this application.

[0036] List of reference numerals in the attached diagram:

[0037] 1、100 Distributed Bragg Reflective Structure 110 First Part 120 Second Part 130 Third Part 1001 First Material Layer 1002 Second Material Layer 200 Substrate 300 Buffer Layer 4、400 Epitaxial Structure 410 First Semiconductor Layer 420 Active Layer 430 Second Semiconductor Layer 5、500 Insulating Protective Layer 610 First Electrode 620 Second Electrode 10 Light Emitting Device 101 Packaging Substrate 102 Light Emitting Element Detailed Implementation

[0038] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0039] It should be noted that the illustrations provided in the embodiments of this application are merely schematic representations of the basic concept of this application. Although the illustrations only show components relevant to this application and are not drawn according to the actual number, shape, and size of components in implementation, the shape, quantity, and proportion of each component can be arbitrarily changed in actual implementation, and the layout of the components may also be more complex. The structures, proportions, sizes, etc., shown in the accompanying drawings are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0040] Example 1

[0041] See Figure 1In traditional flip-chip LEDs, reflective layers are provided on both the back and front sides of the epitaxial structure (or substrate). These reflective layers may include a distributed Bragg reflector (DBR) structure and a metal layer to reflect and / or transmit light emitted from the epitaxial structure. It is noteworthy that the angles of the light emitted from the epitaxial structure are different; for example, there are small-angle light rays L1 and large-angle light rays L2. The angle between light ray L1 and the normal is between 0° and 30°, while the angle between light ray L2 and the normal is between 30° and 60°. To ensure large-angle light emission from the LED chip, the insulating protective layer 5 can perform total internal reflection on both small-angle and large-angle light rays, while the distributed Bragg reflector structure 1 reflects small-angle light rays, allowing large-angle light rays to pass through, promoting light emission from the sides and back to increase the emission angle. However, the wavelength range in which this LED chip can maintain good large-angle light emission is limited. As the wavelength changes, the reflectivity and transmittance of the LED chip for large-angle light also change, leading to poor uniformity of light emission, increased light loss, and reduced chip brightness. Based on the background technology and the aforementioned technical deficiencies, this application provides a DBR structure, a light-emitting diode, and a light-emitting device to effectively solve or improve the above-mentioned technical problems. The technical solution of this application will be described in detail below through embodiments.

[0042] For ease of description, the direction from the substrate to the epitaxial structure is defined as upward, and the opposite direction as downward; the insulating protective layer is located above the epitaxial structure (front side); the distributed Bragg reflector structure is located below the epitaxial structure (back side).

[0043] like Figures 2~3 As shown, this embodiment provides a light-emitting diode (LED), which includes at least a distributed Bragg reflector structure 100, a substrate 200, an epitaxial structure 400, and an insulating protective layer 500. Specifically:

[0044] See Figures 2~4 The distributed Bragg reflector structure 100 includes at least alternating stacked first material layer 1001 and second material layer 1002, wherein the refractive index of the first material layer 1001 is less than the refractive index of the second material layer 1002. The first material layer 1001 and the second material layer 1002 can be oxides of different materials, having different refractive indices and being optically transparent, such as SiO2, SiN, or SiO2. x N yThe material comprises two or more oxides or nitrides of TiO2, Si3N4, Al2O3, TiN, AlN, ZrO2, TiAlN, or TiSiN. Due to their high transmittance, ease of deposition, and relatively large refractive index difference, SiO2 and TiO2 are preferred as the first material layer in this embodiment, with a refractive index of approximately 1.47, and TiO2 is preferred as the second material layer, with a refractive index of approximately 2.55. It is understood that the first material layer 1001 and the second material layer 1002 are not limited to the aforementioned SiO2 and TiO2 layers.

[0045] This embodiment provides a distributed Bragg reflection structure; see [link to documentation]. Figure 3 Along the thickness direction of the distributed Bragg reflection structure, that is, from bottom to top, the distributed Bragg reflection structure 100 is divided into a first part 110, a second part 120, and a third part 130. By improving the design of the film system of the distributed Bragg reflection structure 100, the structure optimizes the reflection angle range and transmission angle range while having small-angle reflection and large-angle transmission, and is suitable for reflection and transmission of light of different wavelengths. The optimized film system can effectively resist the problems of large-angle light transmission fluctuation and light transmission reduction caused by wavelength changes.

[0046] The first material layer 1001 and the second material layer 1002 of the distributed Bragg reflection structure 100 are described in detail below.

[0047] See Figures 3~4The first part 110 includes several first material layers 1001 with an optical thickness greater than 0.25λ and several first material layers 1001 with an optical thickness less than 0.25λ. Specifically, the first part 110 includes several first material layers with an optical thickness greater than 0.1λ, and at least one first material layer with an optical thickness less than 0.05λ. Further, the first part 110 includes several first material layers with an optical thickness greater than 0.15λ, and at least one first material layer with an optical thickness less than 0.05λ. The first material layer with the smallest optical thickness in the first part 110 (the first minimum thickness layer) can be any layer in the middle of the first part 110, rather than being the starting layer or the last layer of the first part 110. Furthermore, the two adjacent first material layers above and below the first material layer with the smallest optical thickness both have a large optical thickness, for example, greater than 0.30λ or greater than 0.35λ. That is, the first material layer 1001 of the first part 110 is configured as a film group with a large difference and fluctuation in optical thickness, so that the maximum difference in optical thickness of the first material layers in the first part 110 is greater than or equal to 0.3λ. By changing the thickness of certain layers in the middle of the first part 110, the phase of the reflected light can be adjusted, thereby achieving constructive interference at a specific wavelength and enhancing reflectivity. Adjusting the position or intensity of the defect mode, specific reflection or transmission characteristics, can meet specific application requirements. The reflection bandwidth of the DBR structure depends on various factors such as the refractive index difference, thickness, and number of periods of each layer. By controlling the thickness difference of the first material layers in the first part 110, for example, making certain layers thinner or thicker, errors caused by process fluctuations can also be compensated, achieving precise control of the reflection bandwidth to ensure that the overall performance of the DBR structure 100 meets the design requirements. Furthermore, the first material layers adjacent to the first minimum thickness layer are the two first material layers with the largest optical thickness in the first part 110. Specifically, the optical thickness of the two first material layers with the largest optical thickness is greater than 0.30λ or greater than 0.35λ. Furthermore, the difference between the optical thickness of the minimum first thickness layer and the optical thickness of the first material layers on both sides is greater than 0.3λ.

[0048] In some embodiments, the number of alternately stacked membrane units in the first portion 110 is between 3 and 8 pairs, for example, 4, 5, 6, or 7 pairs. Further, the number of alternately stacked membrane units in the first portion 110 is between 4 and 6 pairs. See also Figure 4 In the DBR structure provided in this embodiment, the first part 110 includes 10 material layers from bottom to top, namely 1 to 10 layers, which is 5 pairs of membrane modules.

[0049] In some embodiments, the first portion 110 includes a plurality of film groups, each film group including adjacent first material layers 1001 and second material layers 1002, wherein the optical thickness of the first material layer in at least one film group is less than the optical thickness of the second material layer. It will be understood that the number of film groups having the above characteristics increases or decreases depending on the number of material layers in the first portion 110. See also Figure 4 In the DBR structure provided in this embodiment, only the optical thickness of the first material layer of a pair of film groups is less than the optical thickness of the second material layer. This film group is the fourth pair arranged from bottom to top in the first part 110.

[0050] In the above embodiments, the optical thickness of the second material layer 1002 is less than or equal to 0.2λ, and the optical thickness of the second material layer 1002 exhibits a "V"-shaped gradual distribution from bottom to top, that is, the optical thickness of the second material layer 1002 shows a trend of first decreasing and then increasing. Further, the optical thickness of the second material layer 1002 is less than or equal to 0.15λ. For all layers in the first part 110 other than the first material layer with the smallest optical thickness, the optical thickness of the first material layer 1001 in the first part 110 is greater than the optical thickness of the second material layer 1002 in the first part 110. Further, in each DBR material layer pair, for all layers other than the first minimum thickness layer, the optical thickness of the first material layer 1001 in each layer pair is greater than the optical thickness of the second material layer 1002 in the same layer pair. Furthermore, the optical thickness of the second material layer 1002 in the first part 110 is distributed in a "V" shape from bottom to top. The first material layer with the smallest optical thickness in the first part 110 is in contact with the second material layer with the smallest optical thickness. The second material layers in contact with the first minimum thickness layer are the two minimum thickness layers in the first part 110. That is, the three smallest material layers in the first part 110 are, in order, the second material layer / the first material layer / the second material layer, and the optical thickness of the first material layer located in the middle of the sandwich is less than the optical thickness of the second material layers on both sides. Furthermore, the optical thickness of the three sandwich layers is less than 0.1λ. Furthermore, among the second material layers in contact with the minimum first thickness layer, at least one layer has an optical thickness less than 0.05λ.

[0051] See also Figures 3~4In the second region 120, the optical thickness of the first material layer 1001 is between 0.3λ and 0.45λ, and the optical thickness of the second material layer 1002 is between 0.1λ and 0.2λ. It is understood that a material layer with a high refractive index has a higher light absorption rate than a material layer with a low refractive index; therefore, the optical thickness of the first material layer 1001 with a low refractive index is designed to be greater than the optical thickness of the second material layer 1002 with a high refractive index. Further, the optical thickness of the first material layer 1001 in the second region 120 is between 0.35λ and 0.45λ, and the optical thickness of the second material layer 1002 in the second region 120 is between 0.1λ and 0.15λ. Specifically, in the second region 120, which has a relatively large optical thickness and a relatively large number of film layers, the thickness of the second material layer 1002 can be relatively reduced to decrease the brightness loss caused by light absorption by the second material layer 1002. The optical thickness of the first material layer 1001 in Part 2 120 can be set in an alternating "thick-thin-thick" sequence, or it can be set randomly, as long as the optical thickness is between 0.30λ and 0.45λ. Adjusting the thickness of the first material layer in Part 2 120 according to the actual application achieves stable reflectivity and reflection band of the DBR structure. Furthermore, the optical thickness of the first material layer 1001 in Part 2 120 is between 0.37λ and 0.42λ. The thickness setting of the second material layer 1002 in Part 2 120 is similar and will not be elaborated here.

[0052] In some embodiments, the maximum difference in optical thickness of the first material layer 1001 in the second portion 120 is less than or equal to 0.05λ, meaning the thickness of the first material layer in the second portion 120 is relatively uniform to maintain relatively stable reflection characteristics. Similarly, the thickness of the second material layer in the second portion 120 is also relatively uniform, and its maximum difference in optical thickness is also less than or equal to 0.05λ, to match the optical thickness of the first material layer in that portion. Further, the maximum difference in optical thickness of the first material layer 1001 in the second portion 120 is less than or equal to 0.03λ, and the maximum difference in optical thickness of the second material layer 1002 is less than or equal to 0.03λ.

[0053] In some embodiments, the optical thickness of the first first material layer in the second portion 120 is the same as or the optical thickness of the last first material layer in the first portion 110 is less than 0.01λ. Further, the last first material layer in the first portion 110 may be the material layer with the largest optical thickness in the first portion 110 adjacent to the smallest first thickness layer.

[0054] In some embodiments, the optical thickness of the first second material layer in the second portion 120 is the same as or the optical thickness of the last second material layer in the first portion 110 is less than 0.01λ. Further, the two second material layers with the largest optical thickness in the first portion 110 are the starting layer and the ending layer of the first portion 110, respectively. The first second material layer in the second portion 120 is in contact with the ending layer of the first portion 110, and the optical thickness of the ending layer is between 0.11λ and 0.14λ.

[0055] In some embodiments, the number of alternately stacked film groups in the second part 120 is between 4 and 10 pairs, for example, 5, 6, 8, or 9 pairs. Further, the number of alternately stacked film groups in the second part 120 is between 5 and 7 pairs. Further, the number of alternately stacked film groups in the second part 120 is greater than the number of alternately stacked film groups in the first part 120 to ensure that the DBR structure has more stable reflection characteristics. It is understood that the number of alternately stacked film groups in the second part should not be too large, for example, exceeding 10 pairs, as this may have a negative impact on light absorption by the material layer and increase the difficulty of the process. See also Figure 4 In this embodiment, the second part 120 of the DBR structure includes 12 material layers from the 11th to the 22nd layer from bottom to top, that is, 6 pairs of membrane groups, which is greater than the number of 5 pairs of membrane groups in the first part 110.

[0056] See also Figures 3~4 In the third part 130, the optical thickness of the first material layer 1001 is between 0.3λ and 0.45λ, and the difference in optical thickness of the first material layer 1001 in the third part 130 is greater than the difference in optical thickness of the first material layer 1001 in the second part 120. That is, the thickness fluctuation of the first material layer in the third part 130 is greater than the difference in the first material layer in the second part 120, but it is still within a relatively uniform optical thickness range. There is no design to make a steep increase or decrease in the thickness of one or several layers. Furthermore, the optical thickness of the first material layer 1001 in the third part 130 is between 0.35λ and 0.45λ.

[0057] In some embodiments, the third part 130 includes a first group and a second group of first material layers 1001 stacked in a cross-lamination. The optical thickness of the first material layers in the first group is greater than the optical thickness of the first material layers in the adjacent second group. Specifically, the optical thickness of the first material layers in the first group ranges from 0.4λ ± 10%, and the optical thickness of the first material layers in the second group ranges from 0.37λ ± 10%. This optical thickness setting allows the DBR structure to increase reflectivity in a wavelength range longer than the center wavelength.

[0058] In some embodiments, the optical thickness of the second material layer 1002 in the third portion 130 decreases sequentially from bottom to top. The first second material layer 1002 in the third portion 130, adjacent to the last second material layer in the second portion 120, has the largest optical thickness, which is between 0.10λ and 0.15λ. Further, the optical thickness of the first second material layer in the third portion 130 is between 0.11λ and 0.14λ. Further, the average optical thickness of the second material layer 1002 in the second portion 120 is greater than the average optical thickness of the second material layer 1002 in the third portion 130.

[0059] In some embodiments, the number of alternately stacked film units in the third part 130 is between 2 and 6 pairs, such as 3, 4, or 5 pairs. For the DBR structure as a whole, the more layers the DBR has, the higher the reflectivity theoretically, but this also increases manufacturing complexity and cost. The number of alternately stacked film units in the third part 130 is less than the number of alternately stacked film units in the second part 120 to ensure that the DBR structure has more stable reflective characteristics while keeping cost and manufacturing difficulty under control. See also Figure 4 In this embodiment, the third part 130 of the DBR structure includes eight material layers from the 23rd to the 30th layer from bottom to top, which is four pairs of membrane groups, less than the six pairs of membrane groups in the second part 120.

[0060] In some embodiments, the starting layer of the first part 110, i.e., the first material layer at the bottom, can be either a first material layer 1001 or a second material layer 1002. Generally, since the adhesion strength of SiO2 is higher than that of TiO2, the last layer in contact between the distributed Bragg reflection structure 100 and the substrate 200, i.e., the top material layer, is preferably the first material layer 1001 made of SiO2. The optical thickness design of this layer only needs to meet the film system design requirements of the third part 130.

[0061] See Figure 3 This embodiment also provides a distributed Bragg reflection structure, in which at least one of the multiple first material layers has an optical thickness less than the optical thickness of any second material layer.

[0062] In an optional embodiment, the optical thickness of the first material layer 1001 having the minimum optical thickness is less than 0.05λ, and the optical thickness of the first material layers 1001 adjacent to both sides of the first material layer 1001 is greater than 0.3λ. Further, along the thickness direction of the distributed Bragg reflection structure, it sequentially includes a first portion 110, a second portion 120, and a third portion 130:

[0063] The first part 110 includes a plurality of first material layers 1001 and a plurality of second material layers 1002. The first material layers 1001 include a plurality of first material layers with an optical thickness greater than 0.1λ, and at least one first material layer with an optical thickness less than 0.05λ.

[0064] Both the second part 120 and the third part 130 include a plurality of first material layers 1001 and a plurality of second material layers 1002, wherein the optical thickness of the first material layer 1001 is between 0.3λ and 0.45λ.

[0065] The first material layer with the minimum optical thickness is located in the plurality of first material layers in the first part 110.

[0066] In an optional embodiment, the optical thickness of the second material layer 1002 is less than 0.2λ. Further, the optical thickness of the second material layer 1002 is less than 0.15λ.

[0067] In an optional embodiment, the first part 110 includes a plurality of film groups, each film group including an adjacent first material layer 1001 and a second material layer 1002, wherein the optical thickness of the first material layer in at least one film group is less than the optical thickness of the second material layer.

[0068] This embodiment also provides a distributed Bragg reflection structure, which has the following characteristics:

[0069] The first part 110 includes a plurality of first material layers and a plurality of second material layers, wherein the first material layer includes at least one first material layer with an optical thickness of less than 0.1λ, and the second material layer includes at least one second material layer with an optical thickness of less than 0.1λ;

[0070] The second part 120 includes a plurality of first material layers and a plurality of second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ;

[0071] The third part 130 includes a plurality of first material layers and a plurality of second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ, and the second material layers include at least one second material layer with an optical thickness less than 0.1λ;

[0072] Where λ is 444 nm.

[0073] When the layer thickness meets specific phase conditions, the DBR structure may exhibit transmission windows at certain wavelengths, thereby increasing transmittance. As the incident angle increases, the optical path difference between each film layer decreases, and the reflection spectrum of the DBR structure shifts towards shorter wavelengths. When the incident light angle is large, the propagation path of light in the DBR layer increases, leading to a phase change. This may cause the reflected light to no longer match the phase of the incident light, thus reducing reflectivity and allowing more light to pass through. Conversely, the phase change of small-angle incident light is smaller, resulting in higher reflectivity. The above module design can effectively resist the problem of reduced transmittance at large angles caused by wavelength changes, promoting the emission of large-angle incident light of different wavelengths from both the side and back of the LED, improving the uniformity of light output. Within a large incident angle range, the DBR structure with the above film system can maintain a stable and uniform transmittance of light regardless of the incident angle.

[0074] See also Figure 2 The substrate 200 is located on the DBR structure 100. The substrate 200 can be any transparent substrate, including but not limited to sapphire substrates or SiC substrates. Further, the substrate 200 may have a predetermined pattern formed on its upper surface, such as a patterned sapphire substrate (PSS). Since patterned sapphire substrates have better transmittance for light with incident angles ranging from 20° to 50°, the advantageous effects can be more effectively demonstrated when combined with the large-angle DBR structure provided in this application. The thickness of the substrate 200 is between 100 μm and 500 μm.

[0075] See also Figure 2 The buffer layer 300 is located on the substrate 200, specifically between the substrate 200 and the epitaxial structure 400. The buffer layer 300 is an n-type material layer made of GaN-based III-V group nitride semiconductor, or an undoped material layer, or a combination of multiple layers with varying composition, used to adjust the warpage of the substrate 200 to improve wavelength uniformity.

[0076] See also Figure 2The epitaxial structure 400 is located above the buffer layer 300 and includes a first semiconductor layer 410, an active layer 420, and a second semiconductor layer 430 stacked sequentially. The first semiconductor layer 410 is composed of a III-V or II-VI compound semiconductor and is doped with N-type dopants such as Si, Ge, Sn, Se, or Te, making it an N-type semiconductor layer. The second semiconductor layer 430 is composed of a III-V or II-VI compound semiconductor and is doped with P-type dopants such as Mg, Zn, Ca, Sr, or Ba, making it a P-type semiconductor layer. The first semiconductor layer 410 provides electrons for recombination emission, and the second semiconductor layer 430 provides holes for recombination emission. The active layer 420 can have any structure, but is not limited to, a single-well structure, a multi-well structure, a single quantum well structure, or a multi-quantum well structure, for electron and hole recombination emission. The wavelength of the light emitted from the active layer 420 may vary depending on the material of the active layer 420. Therefore, the DBR structure can be fabricated with reference to the center wavelength λ, the first wavelength λ1, and the second wavelength λ2. In this embodiment, the center wavelength λ is 444nm, the first wavelength λ1 is 410nm, and the second wavelength λ2 is 480nm, in order to achieve effective reflection of light emitted from the active layer, while maintaining high reflectivity relative to light entering the DBR at various small angles of incidence. When light emitted from the active layer 420 at various angles reaches the DBR structure on the back side of the substrate 200, the small-angle light is reflected back into the LED by the DBR structure 100. A portion of the small-angle light is reflected multiple times by the insulating protective layer 500 on the front side of the LED and the DBR structure 100 to form large-angle light, which is emitted from the back side of the LED chip. Another portion of the small-angle light is converted into heat loss during multiple reflections inside the LED chip. The large-angle light is emitted directly through the DBR structure 100 on the back side of the LED chip, thereby ensuring large-angle light emission from the chip.

[0077] See also Figure 2 An insulating protective layer 500 is formed on the epitaxial structure 400 to reflect light reflected from the epitaxial structure 400 and the distributed Bragg reflector structure 100. In an optional embodiment, the insulating protective layer 500 can be configured as a DBR layer, which is formed by alternately stacking a first material layer and a second material layer. The first material layer has a first refractive index, such as a SiO2 layer with a refractive index of approximately 1.47, and the second material layer has a second refractive index, such as a TiO2 layer with a refractive index of approximately 2.55. The insulating protective layer 500 can reflect almost all light from inside the chip back to the chip and cause the light to exit at a large angle on the back side of the chip.

[0078] In some embodiments, the light-emitting diode chip may further include an intermediate layer disposed between the substrate 200 and the DBR structure 100, and having the same material composition as the first material layer 1001 in the DBR structure 100, wherein the intermediate layer has a greater thickness than the first material layer 1001. The insertion of the intermediate layer reduces the impact of the rough bottom surface of the substrate 200 on the DBR formed on the back side of the substrate.

[0079] In some embodiments, the LED chip may further include a surface layer disposed on top of the DBR. The surface layer is formed of the same material as the first material layer in the DBR, such as SiO2, and has a thickness greater than that of the first material layer. The surface layer can prevent the DBR structure from being damaged by the rough surface of the LED mounting plane during packaging.

[0080] The light-emitting diode provided in this embodiment is a flip-chip light-emitting diode that emits blue light with a wavelength between 410nm and 480nm. This flip-chip light-emitting diode is a small-sized flip-chip light-emitting diode, such as a mini flip-chip light-emitting diode or a micro flip-chip light-emitting diode.

[0081] This embodiment also provides a distributed Bragg reflection structure, see [link to documentation]. Figures 2~5 The structure comprises at least alternating stacked first material layer 1001 and second material layer 1002. The refractive index of the first material layer 1001 is less than that of the second material layer 1002. The first material layer is preferably SiO2 with a refractive index of approximately 1.47, and the second material layer is preferably TiO2 with a refractive index of approximately 2.55. The first material layer 1001 includes several film layers with an optical thickness greater than 0.35λ and at least one film layer with an optical thickness less than 0.1λ. The optical thickness of the second material layer 1002 is less than 0.2λ for all layers. The light emitted by the light-emitting diode provided in this embodiment has a peak wavelength between 410nm and 480nm, and within an incident angle range of 30° to 60°, the transmittance of the distributed Bragg reflector structure 100 is greater than or equal to 90%. Furthermore, in the distributed Bragg reflection structure provided in this embodiment, the first material layer 1001 includes several film layers with an optical thickness greater than 0.35λ and at least one film layer with an optical thickness less than 0.05λ, and the optical thickness of the second material layer 1002 is less than 0.15λ, where λ is 444nm.

[0082] See Figure 5 In some embodiments, the reflectivity of the distributed Bragg reflector structure 100 forms a reflection curve as the incident angle increases. The reflection curve includes a first reflection segment, a plateau segment, a second reflection segment, and a light-transmitting segment connected in sequence.

[0083] The following section details the segmental changes in the light reflection curve. See also...Figure 5 This embodiment provides three "incident angle-reflectivity" curves with a center wavelength λ of 444nm, a first wavelength λ1 of 410nm, and a second wavelength λ2 of 480nm, which correspond to the center curve C, the first curve C1, and the second curve C2, respectively.

[0084] First, as the incident angle gradually increases from 0 degrees to a certain angle, the reflectivity of this DBR structure for light in all wavelength bands approaches 100%, meaning that light at small angles can be completely reflected back into the LED. This section of the curve represents the initial segment. Figure 5 As can be seen, the initial reflection curves of the three curves basically overlap. The reflectivity of the second curve C2 in the incident angle range of 0 to 15 degrees, the central curve C in the incident angle range of 0 to 25 degrees, and the first curve in the incident angle range of 0 to 30 degrees are all close to 100%.

[0085] As the angle of incidence continues to increase, the reflectivity of the light in the initial segment reaches the first steep inflection point and then rapidly decreases until it reaches the plateau segment. This segment of the reflectivity curve with a steep drop is the first reflection segment. The incident angle range corresponding to the first reflection segment is relatively narrow, and the reflectivity changes significantly, typically decreasing from nearly 100% to about 50%. For light of different wavelengths, the angular span of the first reflection segment is basically consistent, and this angular span does not change with wavelength. Furthermore, the starting angle of the first reflection segment changes with wavelength; the shorter the wavelength, the larger the steep starting angle of the first reflection segment; the longer the wavelength, the smaller the steep starting angle of the first reflection segment.

[0086] As the incident angle continues to increase, the reflectivity of the first reflection segment reaches a plateau and then stabilizes, with the reflectivity of the light in the plateau segment ranging from 40% to 60%. Furthermore, the angle range of the plateau segment is between 5 and 15 degrees. Depending on the wavelength of the emitted light, the curve characteristics of the plateau segment also differ; the shorter the wavelength, the longer the plateau segment; and the longer the wavelength, the shorter the plateau segment. For light of different wavelengths, the reflectivity range of the plateau segment is the same, and this value does not change with wavelength. Furthermore, the emissivity of the plateau segment is between 50% and 55%. Figure 5 As can be seen, the reflectivity of the plateau segments of the three curves is around 50%. Among them, the incident angle range of the plateau segment of the second curve C2 is relatively small, between 20 degrees and 25 degrees; the incident angle range of the plateau segment of the central curve C increases, between 25 degrees and 35 degrees; and the incident angle range of the plateau segment of the first curve C1 continues to increase, between 35 degrees and 45 degrees.

[0087] As the angle of incidence continues to increase, the reflectivity of the light in the plateau segment reaches the second steep inflection point and then continues to decrease rapidly, forming the second reflection segment. The reflectivity of the light in the second reflection segment also shows a decreasing trend until it reaches the transmission segment. Similar to the first reflection segment, the incident angle range corresponding to the second reflection segment is also relatively narrow, and the reflectivity varies significantly, typically decreasing from nearly 50% to below 10%. For light of different wavelengths, the angular span of the second reflection segment is also basically consistent; this angular span does not change with wavelength. Furthermore, the starting angle of the second reflection segment changes with wavelength; the shorter the wavelength, the smaller the steep inflection starting angle of the second reflection segment; the longer the wavelength, the larger the steep inflection starting angle of the second reflection segment.

[0088] As the angle of incidence continues to increase, the reflectivity of the second reflection segment reaches the transmission segment and then stabilizes again, with the reflectivity of the transmission segment being less than 10%. Furthermore, the average reflectivity of the transmission segment is less than 5%. Figure 5 As can be seen, the reflectivity of the light-transmitting segments of all three curves is below 10%, or less than 5%. Among them, the second curve C2 has the largest range of incident angles in its light-transmitting segment, between 25 degrees and 60 degrees, and its reflectivity is less than 5%. The central curve C has a smaller range of incident angles in its light-transmitting segment, between 35 degrees and 60 degrees, and its reflectivity is also less than 5%. The first curve C1 has a further smaller range of incident angles in its light-transmitting segment, between 45 degrees and 60 degrees, and its average reflectivity is still less than 5%.

[0089] By precisely controlling the thickness and material properties of each layer, light can undergo multiple constructive interferences within the DBR structure, significantly altering its reflectivity. This allows the DBR structure to exhibit very high or very low reflectivity, even approaching 100% or 0%, within specific wavelength ranges. By adjusting the thickness and refractive index differences of the DBR layers, the DBR can be designed to reflect or transmit light within specific wavelength ranges, thereby achieving control over the LED emission spectrum. Figure 5 It can be seen that within the incident angle range of 30° to 60°, as the wavelength of the incident light decreases, the length of the plateau segment of the reflection curve increases, while the length of the transmission segment decreases. The lengths of the plateau segment and the transmission segment are complementary. With the change of wavelength, the reflection curve only shifts, without any reduction in light transmission, effectively resisting the problems of reflectivity fluctuations and severe distortion of the reflection curve caused by wavelength changes. Example 2

[0090] See Figure 6This embodiment also provides a light-emitting device 10, which is a flip-chip LED product, including a packaging substrate 101; at least one light-emitting diode disposed on the surface of the packaging substrate 101, and the packaging substrate 101 and the electrode structure of the light-emitting diode are electrically connected. The light-emitting element 102 is the light-emitting diode provided in Embodiment 1 of this application, and the light-emitting diode is electrically connected to the packaging substrate 101 through a first electrode 610 and a second electrode 620. The light-emitting diode provided in Embodiment 1, by optimizing the film system composition of the distributed Bragg reflection structure, can effectively resist the problem of large-angle light transmission reduction caused by wavelength changes, and promote the emission of light of different wavelengths from the side and back of the light-emitting diode, thereby increasing chip brightness and improving the uniformity of light emission. Therefore, the light-emitting device 10 also has the above-mentioned excellent effects.

[0091] In summary, the DBR structure, light-emitting diode, and light-emitting device provided in this application effectively overcome the various shortcomings of the prior art and have high industrial application value.

[0092] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A distributed Bragg reflection structure, characterized in that, It includes at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than the refractive index of the second material layer; Along the thickness direction of the distributed Bragg reflection structure, the distributed Bragg reflection structure comprises, in sequence: The first part includes multiple first material layers and multiple second material layers, wherein the first material layers include multiple first material layers with an optical thickness greater than 0.1λ, and at least one first material layer with an optical thickness less than 0.05λ; The second part includes multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ. The third part includes multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ, and the difference in optical thickness of the first material layers in the third part is greater than the difference in optical thickness of the first material layers in the second part.

2. A distributed Bragg reflection structure, characterized in that, It includes at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than the refractive index of the second material layer; Along the thickness direction of the distributed Bragg reflection structure, the distributed Bragg reflection structure comprises, in sequence: The first part includes multiple first material layers and multiple second material layers, wherein the first material layer includes at least one first material layer with an optical thickness of less than 0.1λ, and the second material layer includes at least one second material layer with an optical thickness of less than 0.1λ. The second part includes multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ. The third part includes multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layers is between 0.3λ and 0.45λ, and the second material layers include at least one second material layer with an optical thickness of less than 0.1λ.

3. The distributed Bragg reflection structure according to claim 1 or 2, characterized in that, The distributed Bragg reflection structure includes at least one first material layer with an optical thickness less than the optical thickness of any second material layer.

4. The distributed Bragg reflection structure according to claim 1 or 2, characterized in that, The first part includes a plurality of film groups, each of the film groups including an adjacent first material layer and a second material layer, wherein the optical thickness of the first material layer in at least one film group is less than the optical thickness of the second material layer.

5. A distributed Bragg reflection structure, characterized in that, It includes at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than the refractive index of the second material layer; The first material layer includes at least one first material layer with an optical thickness less than the optical thickness of any second material layer; Along the thickness direction of the distributed Bragg reflection structure, the distributed Bragg reflection structure sequentially comprises a first part, a second part, and a third part: The first part includes a plurality of first material layers and a plurality of second material layers. The first material layers include a plurality of first material layers with an optical thickness greater than 0.1λ, and at least one first material layer with an optical thickness less than 0.05λ. Both the second part and the third part include multiple first material layers and multiple second material layers, wherein the optical thickness of the first material layer is between 0.3λ and 0.45λ; The first material layer with the minimum optical thickness is located in the first material layer of the first part.

6. The distributed Bragg reflection structure according to claim 5, characterized in that, The optical thickness of the first material layer with the minimum optical thickness is less than 0.05λ, and the optical thickness of the first material layers adjacent to the first material layer on both sides is greater than 0.3λ.

7. The distributed Bragg reflection structure according to claim 5, characterized in that, The optical thickness of the second material layer is less than 0.2λ.

8. The distributed Bragg reflection structure according to claim 5, characterized in that, The first part includes a plurality of film groups, each of the film groups including an adjacent first material layer and a second material layer, wherein the optical thickness of the first material layer in at least one film group is less than the optical thickness of the second material layer.

9. The distributed Bragg reflection structure according to claim 1, 2, or 5, characterized in that, The maximum difference in optical thickness of the first material layer in the first part is greater than or equal to 0.3λ.

10. The distributed Bragg reflection structure according to claim 1, 2, or 5, characterized in that, The maximum difference in optical thickness of the first material layer in the second part is less than or equal to 0.05λ.

11. The distributed Bragg reflection structure according to claim 1, 2, or 5, characterized in that, The number of membrane units stacked alternately in the second part is greater than the number of membrane units stacked alternately in the first part; The number of membrane modules stacked alternately in the second part is greater than the number of membrane modules stacked alternately in the third part.

12. The distributed Bragg reflection structure according to claim 11, characterized in that, The number of alternatingly stacked membrane units in the first part is between 3 and 8 pairs; The number of alternating stacked membrane units in the second part is between 4 and 10 pairs; The number of alternating stacked membrane units in the first part is between 2 and 6 pairs.

13. The distributed Bragg reflection structure according to claim 1, 2, or 5, characterized in that, The optical thickness of the second material layer is less than or equal to 0.2λ.

14. The distributed Bragg reflection structure according to claim 1, 2, or 5, characterized in that, The first material layer with the minimum optical thickness is in contact with the second material layer with the minimum optical thickness.

15. A distributed Bragg reflection structure, characterized in that, It includes at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than that of the second material layer; the first material layer includes several film layers with an optical thickness greater than 0.35λ and at least one film layer with an optical thickness less than 0.1λ, and the optical thickness of the second material layer is less than 0.2λ; along the thickness direction of the distributed Bragg reflection structure, the distributed Bragg reflection structure sequentially includes a first part, a second part and a third part; The first part includes a plurality of first material layers with an optical thickness greater than 0.1λ, and at least one first material layer with an optical thickness less than 0.05λ; The optical thickness of the first material layer in both the second part and the third part is between 0.3λ and 0.45λ. Within the incident angle range of 30° to 60°, the transmittance of the distributed Bragg reflection structure is greater than or equal to 90%.

16. The distributed Bragg reflection structure according to claim 15, characterized in that, The first part includes a plurality of film groups, each of the film groups including an adjacent first material layer and a second material layer, wherein the optical thickness of the first material layer in at least one film group is less than the optical thickness of the second material layer.

17. The distributed Bragg reflection structure according to claim 1, 2, 5 or 15, characterized in that, The first material layer is SiO2, and the second material layer is TiO2.

18. A light-emitting diode, characterized in that, At least including: A substrate having opposing first and second surfaces; An epitaxial structure is formed on a first surface of the substrate, the epitaxial structure comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked sequentially. A distributed Bragg reflection structure is located on a second surface of the substrate. The distributed Bragg reflection structure includes at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than the refractive index of the second material layer. Along the thickness direction of the distributed Bragg reflection structure, the distributed Bragg reflection structure sequentially includes: a first part, comprising several first material layers with an optical thickness greater than 0.15λ, and at least one first material layer with an optical thickness less than 0.1λ; The second part has an optical thickness of 0.3λ to 0.45λ for the first material layer; the third part has an optical thickness of 0.3λ to 0.45λ for the first material layer, and the difference in optical thickness of the first material layer in the third part is greater than the difference in optical thickness of the first material layer in the second part.

19. A light-emitting diode, characterized in that, At least including: A substrate having opposing first and second surfaces; An epitaxial structure is formed on a first surface of the substrate, the epitaxial structure comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked sequentially. A distributed Bragg reflection structure is located on the second surface of the substrate. The distributed Bragg reflection structure includes at least alternating stacked first and second material layers, wherein the refractive index of the first material layer is less than that of the second material layer; wherein the first material layer includes a plurality of film layers with an optical thickness greater than 0.35λ and at least one film layer with an optical thickness less than 0.05λ, and the optical thickness of the second material layer is less than 0.2λ; along the thickness direction of the distributed Bragg reflection structure, the distributed Bragg reflection structure sequentially includes a first part, a second part, and a third part; The first part includes a plurality of first material layers with an optical thickness greater than 0.1λ, and at least one first material layer with an optical thickness less than 0.05λ; The optical thickness of the first material layer in both the second part and the third part is between 0.3λ and 0.45λ. Within the incident angle range of 30° to 60°, the transmittance of the distributed Bragg reflection structure is greater than or equal to 90%.

20. The light-emitting diode according to claim 18 or 19, characterized in that, The substrate is a patterned sapphire substrate.

21. The light-emitting diode according to claim 18 or 19, characterized in that, Also includes: An insulating reflective layer, located on the second surface of the epitaxial structure, reflects light from the epitaxial structure and the distributed Bragg reflector structure.

22. The light-emitting diode according to claim 18 or 19, characterized in that, The peak wavelength of the light emitted by the light-emitting diode is 444 nm.

23. A light-emitting device, characterized in that, The light-emitting device includes: Packaging substrate; At least one light-emitting diode is disposed on the surface of the packaging substrate, and the packaging substrate and the electrode structure of the light-emitting diode are electrically connected; the light-emitting diode is the light-emitting diode according to any one of claims 18 to 22.

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