A light-emitting diode with increased light emission angle and its fabrication method

Abstract

This invention discloses a light-emitting diode (LED) with an increased light emission angle and its fabrication method. The LED includes a substrate, an epitaxial layer, and a Bragg reflective layer sequentially stacked on the substrate. The Bragg reflective layer includes a first Bragg reflective layer and a second Bragg reflective layer, or includes only the second Bragg reflective layer. The first Bragg reflective layer is disposed on the epitaxial layer, and the second Bragg reflective layer is disposed on the first Bragg reflective layer or the epitaxial layer. The first Bragg reflective layer includes a first predetermined period of alternating stacked first and second reflective sub-layers, and the second Bragg reflective layer includes a second predetermined period of alternating stacked third and fourth reflective sub-layers, wherein the length of the third reflective sub-layer is less than the length of the fourth reflective sub-layer. This invention solves the technical problem in the prior art where the Bragg reflective layer restricts light emission from the edge of the LED, affecting the light emission angle of the LED.

Description

Technical Field

[0001] This invention relates to the field of semiconductor process technology, and specifically to a light-emitting diode with an increased light emission angle and its fabrication method. Background Technology

[0002] Light-emitting diodes (LEDs) are currently the most promising new semiconductor light source. They are commonly used light-emitting devices that release light through the recombination of electrons and holes. Compared with traditional lighting sources, LEDs have advantages such as long lifespan, high luminous efficiency, no interference, and high cost-effectiveness, making them widely used in traffic signs, outdoor full-color displays, and other fields. With the continuous development of semiconductor technology, the requirements for LEDs are becoming increasingly stringent, demanding a wider light emission angle to improve backlight uniformity and reduce backlight manufacturing costs.

[0003] The common light emission angle of LEDs is 120-140°. Due to the morphology and characteristics of the edge Bragg reflector (DBR) of LEDs, most of the light from the edge is reflected back to the front, resulting in weak edge light emission. This limits the edge light emission and affects the overall light emission angle of the LED device. Increasing the number of LEDs to increase the light emission angle cannot meet the requirements of thinness and power saving of LED devices.

[0004] Therefore, existing light-emitting diodes generally suffer from the technical problem of the Bragg reflector layer restricting light emission from the edge of the diode, thus affecting the light emission angle. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a light-emitting diode (LED) with an increased light emission angle and its fabrication method, thereby solving the technical problem in the prior art where the Bragg reflector layer restricts light emission from the edge of the LED, affecting the light emission angle of the LED.

[0006] One aspect of the present invention is to provide a light-emitting diode with an increased light emission angle, comprising a substrate, wherein the light-emitting diode with an increased light emission angle further comprises:

[0007] An epitaxial layer and a Bragg reflector layer are sequentially stacked on the substrate;

[0008] The Bragg reflector layer includes a first Bragg reflector layer and a second Bragg reflector layer or includes a second Bragg reflector layer. The first Bragg reflector layer is disposed on the epitaxial layer, and the second Bragg reflector layer is disposed on the first Bragg reflector layer or the epitaxial layer. The length of the first Bragg reflector layer or the epitaxial layer is greater than the length of the second Bragg reflector layer.

[0009] The first Bragg reflector layer includes a first reflective sublayer and a second reflective sublayer stacked alternately for a first preset period, and the second Bragg reflector layer includes a third reflective sublayer and a fourth reflective sublayer stacked alternately for a second preset period, wherein the length of the third reflective sublayer is less than the length of the fourth reflective sublayer.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: The light-emitting diode (LED) with increased emission angle provided by the present invention includes a Bragg reflector layer comprising a first Bragg reflector layer and a second Bragg reflector layer, or including only the second Bragg reflector layer. The first Bragg reflector layer is disposed on an epitaxial layer, and the second Bragg reflector layer is disposed on the first Bragg reflector layer or the epitaxial layer. The length of the first Bragg reflector layer or the epitaxial layer is greater than the length of the second Bragg reflector layer. The edge of the first Bragg reflector layer or the epitaxial layer is not covered by the edge of the second Bragg reflector layer. Light refracted to the edge by the first Bragg reflector layer or the epitaxial layer will exit from the edge of the uncovered second Bragg reflector layer, changing the light emission path at the edge of the LED, thereby enhancing lateral light emission and increasing the emission angle of the LED, i.e., increasing the light emission area of ​​the LED. Furthermore, the second Bragg reflector layer includes a second predetermined period of alternately stacked third and fourth reflector sublayers, the length of the third reflector sublayer being less than the length of the fourth reflector sublayer. The light trapped within the second Bragg emitting layer is emitted laterally through the extended fourth reflective sublayer, further increasing the emission angle of the LED. This reduces the number of LEDs in the display device, achieving the requirements of a thinner and more energy-efficient display. This solves the common technical problem of the Bragg reflective layer restricting light emission from the edges of the LED and affecting its emission angle.

[0011] According to one aspect of the above technical solution, both the first reflective sublayer and the third reflective sublayer are SiO2 thin film layers with a thickness of [missing information]. Both the second reflective sublayer and the fourth reflective sublayer are TiO2 thin film layers with a thickness of [missing information].

[0012] According to one aspect of the above technical solution, the first preset period is 1-13, and the second preset period is 10-25.

[0013] According to one aspect of the above technical solution, the two ends of the first Bragg reflector layer or the epitaxial layer extend beyond the two ends of the second Bragg reflector layer, and the difference at one end is 2-4 μm.

[0014] According to one aspect of the above technical solution, the thickness of the first Bragg reflective layer is 0.1-3 μm, and the thickness of the second Bragg reflective layer is 2-5 μm.

[0015] According to one aspect of the above technical solution, the two ends of the third reflective sublayer are respectively recessed into the two ends of the fourth reflective sublayer, and the difference at one end is 2-10 times the thickness of the third reflective sublayer.

[0016] According to one aspect of the above technical solution, the length of the first Bragg reflector layer is the same as the length of the epitaxial layer.

[0017] According to one aspect of the above technical solution, the substrate is a sapphire substrate.

[0018] Another aspect of the present invention is to provide a method for fabricating a light-emitting diode with an increased light emission angle, the method being used to fabricate the light-emitting diode with an increased light emission angle described in the above-mentioned technical solution, the method comprising:

[0019] Provide a substrate;

[0020] An epitaxial layer and a Bragg reflective layer are sequentially grown on the substrate. The Bragg reflective layer includes a first Bragg reflective layer and a second Bragg reflective layer, or includes a second Bragg reflective layer. The first Bragg reflective layer is grown on the epitaxial layer, and the second Bragg reflective layer is grown on the first Bragg reflective layer or the epitaxial layer. The first Bragg reflective layer includes a first reflective sublayer and a second reflective sublayer stacked alternately for a first preset period, and the second Bragg reflective layer includes a third reflective sublayer and a fourth reflective sublayer stacked alternately for a second preset period.

[0021] A photoresist layer is coated on the second Bragg reflector layer, and the photoresist layer is exposed, developed, hardened and etched so that the length of the second Bragg reflector layer is less than the length of the first Bragg reflector layer or the epitaxial layer.

[0022] The second Bragg reflector layer is etched so that the length of the third reflector sublayer is less than that of the fourth reflector sublayer.

[0023] To further explain, the growth steps of the second Bragg reflector layer include:

[0024] The second Bragg reflector layer is deposited on the first Bragg reflector layer or the epitaxial layer by vapor deposition;

[0025] A photoresist layer with a thickness of 2-15 μm is coated on the second Bragg reflector layer. The photoresist layer is exposed to an energy of 200-1200 MJ. A developer is sprayed to develop the photoresist layer. After development, the temperature is set between 20-150°C, and the photoresist is hardened for 50-200 seconds.

[0026] Ar, BCl3 and CF4 are introduced into the reaction chamber to etch the second Bugler reflective layer so that the length of the second Bugler reflective layer is less than the length of the first Bugler reflective layer or the epitaxial layer.

[0027] The second Bragg reflector layer is placed in a hydrofluoric acid solution with a concentration of 3%-20% and etched for 50-200 seconds to make the length of the third reflector layer smaller than that of the fourth reflector layer. Attached Figure Description

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0029] Figure 1 This is a schematic diagram of the structure of the light-emitting diode with increased light emission angle in the first embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the light-emitting diode with increased light emission angle in the second embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of the light-emitting diode with increased light emission angle in the third embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the structure of the light-emitting diode with increased light emission angle in the fourth embodiment of the present invention;

[0033] Figure 5 This is a flowchart of a method for preparing a light-emitting diode with an increased light emission angle according to the fifth embodiment of the present invention;

[0034] Component symbol explanation in the attached diagram:

[0035] Substrate 10, epitaxial layer 20, Bragg reflector layer 30, first Bragg reflector layer 31, second Bragg reflector layer 32, first reflector sublayer 310, second reflector sublayer 311, third reflector sublayer 320, and fourth reflector sublayer 321. Detailed Implementation

[0036] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0037] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0038] In this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0039] Example 1

[0040] Please see Figure 1 The image shows a light-emitting diode (LED) with an increased light emission angle according to a first embodiment of the present invention. This LED includes a substrate 10; wherein the substrate 10 is a substrate on which the epitaxial layer 20 is grown. Commonly used substrate 10 materials are sapphire (Al2O3), silicon carbide (SiC), and silicon (Si). Different substrate 10 materials require different epitaxial growth techniques, chip processing techniques, and device packaging techniques, and the substrate 10 material determines the development path of semiconductor lighting technology. In this embodiment, the substrate 10 is a sapphire substrate. Sapphire is the most widely used substrate 10 material for LEDs, possessing advantages such as chemical stability, low visible light absorption, and low cost. It is also less likely to react with the epitaxial layer 20, making it a good substrate 10 material.

[0041] An epitaxial layer 20 and a Bragg reflector layer 30 are sequentially stacked on a substrate 10. The epitaxial layer 20 is disposed on the substrate 10 and includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer. The light-emitting layer is disposed between the first semiconductor layer and the second semiconductor layer. The first semiconductor provides electrons or holes, and the second semiconductor provides holes or electrons. When an electric field is applied to both ends, the electrons or holes provided by the first semiconductor migrate towards the second semiconductor, and the holes or electrons provided by the second semiconductor migrate towards the first semiconductor. Electrons and holes recombine radiatively in the light-emitting layer to realize the light emission of the light-emitting diode.

[0042] A Bragg reflector layer 30 is provided on the epitaxial layer 20 to reflect the light emitted from the epitaxial layer 20. Since electrons and holes in the light-emitting layer of the epitaxial layer 20 recombine to emit light, the light in the light-emitting layer will be emitted in all directions (360°). The Bragg reflector layer 30 will reflect all the light away from the substrate 10 back towards the substrate 10, so that most of the emitted light is emitted from the substrate 10 to the outside, thereby significantly improving the light extraction efficiency of the light-emitting diode. The Bragg reflector, or DBR, reflects light at the interface when light passes through different media. The reflectivity is related to the refractive index between the media. Therefore, if thin films with different refractive indices are stacked periodically, when light passes through these thin films with different refractive indices, the light reflected back from each layer undergoes destructive interference due to the change in phase angle, and then combines with each other to obtain strongly reflected light.

[0043] In this embodiment, the Bragg reflector 30 is only the second Bragg reflector 32, which is disposed on the epitaxial layer 20 and has a thickness of 2-5 μm. The two ends of the second Bragg reflector 32 are recessed into the two ends of the epitaxial layer 20, with a difference of 2-4 μm at one end. The edge of the epitaxial layer 20 is not covered by the second Bragg reflector 32 to increase the light emission angle of the light-emitting diode. Due to the morphology and characteristics of the Bragg reflector 30 at the edge of the light-emitting diode, most of the light at the edge is reflected back to the substrate 10, resulting in weak light emission at the edge, thus limiting its light emission. The setting that the edge length of the second Bragg reflector 32 is less than the length of the epitaxial layer 20 will cause the light in the epitaxial layer 20 to be emitted from the edge of the epitaxial layer 20, changing the light emission path at the edge of the light-emitting diode, thereby enhancing lateral light emission, increasing the light emission angle of the light-emitting diode, that is, increasing the light emission area of ​​the light-emitting diode, thereby increasing the light emission angle of the light-emitting diode device, reducing the number of light-emitting diodes in the display device, and meeting the requirements of thin and light-saving display. In addition, if the difference is less than 2μm, the light emission angle of the LED cannot meet the requirements, and the second Bragg emission layer restricts the light emission from the edge of the LED; when the difference is greater than 4μm, the amount of light emitted by the LED towards the substrate 10 is less, which affects the luminous efficiency of the LED.

[0044] In addition, the second Bragg reflective layer 32 includes a second predetermined period of alternately stacked third reflective sublayer 320 and fourth reflective sublayer 321, wherein the length of the third reflective sublayer 320 is less than the length of the fourth reflective sublayer 321. The third reflective sublayer 320 is a SiO2 thin film layer with a thickness of [missing information]. The fourth reflective sublayer 321 is a TiO2 thin film layer with a thickness of [missing information]. The second preset period is 10-25. The two ends of the third reflective sub-layer 320 are respectively recessed into the two ends of the fourth reflective sub-layer 321. The difference at one end is 2-10 times the thickness of the third reflective sub-layer 320. This is used to allow the light trapped in the second Bragg emission layer to be emitted laterally through the longer fourth reflective sub-layer 321, thereby further increasing the light emission angle of the light-emitting diode, that is, increasing the light emission area of ​​the light-emitting diode, improving the uniformity of light emission, and thus increasing the light emission angle of the light-emitting diode device.

[0045] Understandably, the two ends of the third reflective sub-layer 320 are recessed into the two ends of the fourth reflective sub-layer 321, with the difference at one end being 2-10 times the thickness of the third reflective sub-layer 320. When the difference is less than 2-10 times the thickness of the third reflective sub-layer 320, the extended length of the third reflective sub-layer 320 cannot achieve the effect of lateral light emission, thus failing to increase the light emission angle of the light-emitting diode. When the difference is greater than 2-10 times the thickness of the third reflective sub-layer 320, the extended length of the third reflective sub-layer 320 is too long, making the structure unstable and prone to collapse, thus affecting the stability of the light-emitting diode device.

[0046] Specifically, the temperature is set between 100-200℃, the evaporation rate is set to 5-20 A / s, and the evaporation thickness on the epitaxial layer 20 is [missing information]. The SiO2 thin film layer is used as the third reflective sublayer 320.

[0047] Set the temperature between 100-200℃, the evaporation rate to 1-10 A / s, and the evaporation thickness on the third reflective sublayer 320 to be [missing value]. The TiO2 thin film layer is used as the fourth reflective sublayer 321.

[0048] The third reflective sublayer 320 and the fourth reflective sublayer 321 are grown alternately in sequence according to the second preset cycle of 10-25.

[0049] A photoresist layer with a thickness of 2-15 μm is coated on the grown second Bragg reflector layer 32. The photoresist layer is exposed at an energy of 200-1200 MJ. The photoresist layer is developed by spraying a developer. After development, the temperature is set between 20-60℃ and the photoresist is hardened for 50-120 seconds to form a photoresist pattern with vertical edges.

[0050] Ar, BCl3 and CF4 are introduced into the reaction chamber. The second Bragg reflective layer is etched according to the photoresist pattern of the vertical edge so that the second Bragg reflective layer is etched vertically downward to form a right angle edge. The two ends of the second Bragg reflective layer 32 are respectively recessed into the two ends of the epitaxial layer 20, and the difference at one end is 2-4 μm.

[0051] The second Bragg reflector layer 32 is placed in a hydrofluoric acid solution with a concentration of 3%-20% and etched for 50-200 seconds to etch the third reflector sublayer 320 so that the length of the third reflector sublayer 320 etched away is 2-10 times the thickness of the third reflector sublayer 320.

[0052] Compared to existing technologies, the light-emitting diode (LED) with an increased light emission angle provided in this embodiment has the following advantages: In this LED with an increased light emission angle, the Bragg reflector layer is only a second Bragg reflector layer. The length of the second Bragg reflector layer is shorter than the length of the epitaxial layer, and the edge of the epitaxial layer is not covered by the edge of the second Bragg reflector layer. Light from the epitaxial layer will exit from the edge of the uncovered second Bragg reflector layer, changing the light emission path at the edge of the LED and thus enhancing lateral light emission. Simultaneously, the length of the third reflector layer is shorter than the length of the fourth reflector layer, allowing light trapped within the second Bragg reflector layer to exit laterally through the extended fourth reflector layer, further increasing the light emission angle of the LED. This reduces the number of LEDs per unit light emission area in the display device, achieving the requirements of a thinner and more energy-efficient display. Therefore, it solves the common technical problem of the Bragg reflector layer restricting light emission from the edge of the LED and affecting the light emission angle.

[0053] Example 2

[0054] Please see Figure 2 The image shows a light-emitting diode with an increased light-emitting angle provided in the second embodiment of the present invention. The light-emitting diode with an increased light-emitting angle in this embodiment has a basically the same structure as the light-emitting diode with an increased light-emitting angle in the first embodiment, except that:

[0055] The edge of the second Bragg reflective layer 32 is beveled. By controlling the temperature of the photoresist hardening film, the photoresist angle can be changed. The higher the hardening temperature, the smaller the photoresist angle, and the smaller the morphology angle after etching. Similarly, with the beveled edge, the edge of the epitaxial layer 20 is not covered by the second Bragg reflective layer 32, which is used to increase the light emission angle of the light-emitting diode. The two ends of the third reflective sub-layer 320 are respectively recessed into the two ends of the fourth reflective sub-layer 321, so that the light trapped in the second Bragg emission layer is emitted laterally through the longer fourth reflective sub-layer 321, further increasing the light emission angle of the light-emitting diode, that is, increasing the light emission area of ​​the light-emitting diode, improving the uniformity of light emission, changing the light emission path at the edge of the light-emitting diode, thereby enhancing lateral light emission, and thus increasing the light emission angle of the light-emitting diode device.

[0056] Specifically, the temperature is set between 100-200℃, the evaporation rate is set to 5-20 A / s, and the evaporation thickness on the epitaxial layer 20 is [missing information]. The SiO2 thin film layer is used as the third reflective sublayer 320.

[0057] Set the temperature between 100-200℃, the evaporation rate to 1-10 A / s, and the evaporation thickness on the third reflective sublayer 320 to be [missing value]. The TiO2 thin film layer is used as the fourth reflective sublayer 321.

[0058] The third reflective sublayer 320 and the fourth reflective sublayer 321 are grown alternately in sequence according to the second preset cycle of 10-25.

[0059] A photoresist layer with a thickness of 2-15 μm is coated on the grown second Bragg reflector layer 32. The photoresist layer is exposed at an energy of 200-1200 MJ. The photoresist layer is developed by spraying a developer. After development, the temperature is set between 60-150℃ and the photoresist is hardened for 100-200 s to form a photoresist pattern with beveled edges.

[0060] Ar, BCl3 and CF4 are introduced into the reaction chamber. The second Bragg reflective layer is etched according to the photoresist pattern of the bevel edge so that the bevel edge of the second Bragg reflective layer is etched downward to form an acute edge. The two ends of the second Bragg reflective layer 32 are respectively recessed into the two ends of the epitaxial layer 20, and the difference at one end is 2-4 μm.

[0061] The second Bragg reflector layer 32 is placed in a hydrofluoric acid solution with a concentration of 3%-20% and etched for 50-200 seconds to etch the third reflector sublayer 320 so that the length of the third reflector sublayer 320 etched away is 2-10 times the thickness of the third reflector sublayer 320.

[0062] Compared to existing technologies, the light-emitting diode (LED) with increased emission angle provided in this embodiment has the following advantages: In this LED with increased emission angle, the Bragg reflector layer is only a second Bragg reflector layer. The length of the second Bragg reflector layer is shorter than the length of the epitaxial layer, and the edge of the epitaxial layer is not covered by the edge of the second Bragg reflector layer. Light from the epitaxial layer to the edge will exit through the edge of the uncovered second Bragg emitter layer, changing the light emission path at the edge of the LED, thereby enhancing lateral emission and increasing the emission angle of the LED, i.e., increasing the light emission area of ​​the LED. Furthermore, the second Bragg reflector layer is composed of several third and fourth reflector sub-layers arranged in a second preset period, with the length of the third reflector sub-layer being shorter than the length of the fourth reflector sub-layer. This allows light trapped within the second Bragg emitter layer to exit laterally through the extended fourth reflector sub-layer, further increasing the emission angle of the LED and reducing the number of LEDs per unit light emission area in the display device, thus meeting the requirements for a thinner and more energy-efficient display. This solves the common technical problem of the Bragg reflector layer restricting light emission from the edge of the LED and affecting its emission angle.

[0063] Example 3

[0064] Please see Figure 3 The image shows a light-emitting diode with an increased light-emitting angle provided in the third embodiment of the present invention. The light-emitting diode with an increased light-emitting angle in this embodiment has a basically the same structure as the light-emitting diode with an increased light-emitting angle in the first embodiment, except that:

[0065] The Bragg reflector layer 30 includes a first Bragg reflector layer 31 and a second Bragg reflector layer 32. The first Bragg reflector layer 31 is disposed on the epitaxial layer 20, and the second Bragg reflector layer 32 is disposed on the first Bragg reflector layer 31. The length of the first Bragg reflector layer 31 is greater than the length of the second Bragg reflector layer 32. The first Bragg reflector layer 31 includes a first preset period of alternating stacked first reflector sublayers 310 and 311, with a first preset period of 1 to 13. The second Bragg reflector layer 32 includes a second preset period of alternating stacked third reflector sublayers 320 and 321, with a second preset period of 10 to 25. The length of the third reflector sublayer is less than the length of the fourth reflector sublayer.

[0066] In this embodiment, the length of the first Bragg reflector layer 31 is equal to the length of the epitaxial layer 20, so as to wrap the epitaxial layer 20, protect the epitaxial layer 20, improve the reliability of the light-emitting diode, and prevent external impurities from entering the epitaxial layer 20 and affecting the various performances of the epitaxial layer 20. Similarly, the length of the first Bragg reflector 31 is greater than the length of the second Bragg reflector 32. The edge of the first Bragg reflector 31 is not covered by the edge of the second Bragg reflector 32. The light refracted by the first Bragg reflector 31 to the edge will be emitted from the edge of the second Bragg reflector 32 that is not covered, thereby enhancing the lateral light emission and increasing the light emission angle of the light-emitting diode, that is, increasing the light emission area of ​​the light-emitting diode. In addition, the second Bragg reflector 32 is alternately arranged with several third reflector sub-layers 320 and fourth reflector sub-layers 321 in a second preset period. The length of the third reflector sub-layer 320 is less than the length of the fourth reflector sub-layer 321. The light trapped in the second Bragg reflector 320 is emitted laterally through the extended fourth reflector sub-layer 321, further increasing the light emission angle of the light-emitting diode, reducing the number of light-emitting diodes per unit light emission area of ​​the display, and achieving the requirements of thin and light-saving display.

[0067] Specifically, the temperature is set between 100-200℃, the evaporation rate is set to 5-20 A / s, and the evaporation thickness on the epitaxial layer 20 is [missing information]. The SiO2 thin film layer is used as the first reflective sublayer 310.

[0068] The temperature was set between 100-200℃, the evaporation rate was set to 1-10 A / s, and the evaporation thickness on the first reflective sublayer 310 was [missing value]. The TiO2 thin film layer is used as the second reflective sublayer 311.

[0069] The first reflective sublayer 310 and the second reflective sublayer 311 are grown alternately in a first preset cycle of 1-13.

[0070] The temperature was set between 100-200℃, and the evaporation rate was set between 5-20 A / s. The thickness of the evaporation layer on the first Bragg reflective layer 31 after growth was [missing value]. The SiO2 thin film layer is used as the third reflective sublayer 320.

[0071] Set the temperature between 100-200℃, the evaporation rate to 1-10 A / s, and the evaporation thickness on the third reflective sublayer 320 to be [missing value]. The TiO2 thin film layer is used as the fourth reflective sublayer 321.

[0072] The third reflective sublayer 320 and the fourth reflective sublayer 321 are grown alternately in sequence according to the second preset cycle of 10-25.

[0073] A photoresist layer with a thickness of 2-15 μm is coated on the grown second Bragg reflector layer 32. The photoresist layer is exposed at an energy of 200-1200 MJ. The photoresist layer is developed by spraying a developer. After development, the temperature is set between 20-60℃ and the photoresist is hardened for 50-120 seconds to form a photoresist pattern with vertical edges.

[0074] Ar, BCl3 and CF4 are introduced into the reaction chamber. The second Bragg reflective layer is etched according to the photoresist pattern of the vertical edge so that the second Bragg reflective layer is etched vertically downward to form a right angle edge. The two ends of the second Bragg reflective layer 32 are respectively recessed into the two ends of the epitaxial layer 20, and the difference at one end is 2-4 μm.

[0075] The second Bragg reflector layer 32 is placed in a hydrofluoric acid solution with a concentration of 3%-20% and etched for 50-200 seconds to etch the third reflector sublayer 320 so that the length of the third reflector sublayer 320 etched away is 2-10 times the thickness of the third reflector sublayer 320.

[0076] Compared to existing technologies, the light-emitting diode (LED) with increased emission angle provided in this embodiment has the following advantages: The LED with increased emission angle provided by this invention includes a Bragg reflector layer comprising a first Bragg reflector layer and a second Bragg reflector layer. The first Bragg reflector layer is disposed on the epitaxial layer, and the second Bragg reflector layer is disposed on the first Bragg reflector layer. The length of the first Bragg reflector layer is greater than the length of the second Bragg reflector layer. The edge of the first Bragg reflector layer is not covered by the edge of the second Bragg reflector layer. Light refracted to the edge by the first Bragg reflector layer will exit from the edge of the uncovered second Bragg reflector layer, changing the light emission path at the edge of the LED, thereby enhancing lateral emission and increasing the emission angle of the LED, i.e., increasing the emission area of ​​the LED. Furthermore, the second Bragg reflector layer is composed of several third and fourth reflector sublayers arranged in a second preset period. The length of the third reflector sublayer is less than the length of the fourth reflector sublayer. Light trapped within the second Bragg reflector layer is emitted laterally through the extended fourth reflector sublayer, further increasing the emission angle of the LED, reducing the number of LEDs in the display device, and achieving the requirements of a thinner and more energy-efficient display. This solves the common technical problem of Bragg reflectors restricting light emission from the edges of LEDs and affecting the light emission angle of LEDs.

[0077] Example 4

[0078] Please see Figure 4The image shows a light-emitting diode with an increased light-emitting angle provided in the fourth embodiment of the present invention. The light-emitting diode with an increased light-emitting angle in this embodiment has a basically the same structure as the light-emitting diode with an increased light-emitting angle in the first embodiment, except that:

[0079] The Bragg reflector layer 30 includes a first Bragg reflector layer 31 and a second Bragg reflector layer 32. The first Bragg reflector layer 31 is disposed on the epitaxial layer 20, and the second Bragg reflector layer 32 is disposed on the first Bragg reflector layer 31. The length of the first Bragg reflector layer 31 is greater than the length of the second Bragg reflector layer 32. The first Bragg reflector layer 31 includes a first reflective sublayer 310 and a second reflective sublayer 311 stacked alternately for a first preset period. The second Bragg reflector layer 32 includes a third reflective sublayer 320 and a fourth reflective sublayer 321 stacked alternately for a second preset period. The length of the third reflective sublayer 320 is less than the length of the fourth reflective sublayer 321. The length of the first Bragg reflector layer 31 is equal to the length of the epitaxial layer 20, so as to encapsulate the epitaxial layer 20, protect the epitaxial layer 20, and prevent external impurities from entering the epitaxial layer 20 and affecting its various properties.

[0080] Furthermore, the edge of the second Bragg reflective layer 32 is beveled. By controlling the temperature of the photoresist hardening film, the photoresist angle can be changed. The higher the hardening film temperature, the smaller the photoresist angle, and the smaller the morphology angle after etching. Similarly, with the beveled design, the length of the first Bragg reflector 31 is greater than the length of the second Bragg reflector 32. The edge of the first Bragg reflector 31 is not covered by the edge of the second Bragg reflector 32. The light refracted by the first Bragg reflector 31 to the edge will be emitted from the edge of the uncovered second Bragg reflector, thereby enhancing lateral light emission and increasing the light emission angle of the LED, i.e., increasing the light emission area of ​​the LED. In addition, the second Bragg reflector 32 is alternately arranged with several third reflector sub-layers 320 and fourth reflector sub-layers 321 in a second preset period. The length of the third reflector sub-layer 320 is less than the length of the fourth reflector sub-layer 321. This is used to laterally emit light trapped in the second Bragg reflector through the extended fourth reflector sub-layer 321, further increasing the light emission angle of the LED, reducing the number of LEDs per unit light emission area of ​​the display, and achieving the requirements of a thin and light-saving display.

[0081] Specifically, the temperature is set between 100-200℃, the evaporation rate is set to 5-20 A / s, and the evaporation thickness on the epitaxial layer 20 is [missing information]. The SiO2 thin film layer is used as the first reflective sublayer 310.

[0082] The temperature was set between 100-200℃, the evaporation rate was set to 1-10 A / s, and the evaporation thickness on the first reflective sublayer 310 was [missing value]. The TiO2 thin film layer is used as the second reflective sublayer 311.

[0083] The first reflective sublayer 310 and the second reflective sublayer 311 are grown alternately in a first preset cycle of 1-13.

[0084] The temperature was set between 100-200℃, and the evaporation rate was set between 5-20 A / s. The thickness of the evaporation layer on the first Bragg reflective layer 31 after growth was [missing value]. The SiO2 thin film layer is used as the third reflective sublayer 320.

[0085] Set the temperature between 100-200℃, the evaporation rate to 1-10 A / s, and the evaporation thickness on the third reflective sublayer 320 to be [missing value]. The TiO2 thin film layer is used as the fourth reflective sublayer 321.

[0086] The third reflective sublayer 320 and the fourth reflective sublayer 321 are grown alternately in sequence according to the second preset cycle of 10-25.

[0087] A photoresist layer with a thickness of 2-15 μm is coated on the grown second Bragg reflector layer 32. The photoresist layer is exposed at an energy of 200-1200 MJ. The photoresist layer is developed by spraying a developer. After development, the temperature is set between 60-150℃ and the photoresist is hardened for 100-200 s to form a photoresist pattern with beveled edges.

[0088] Ar, BCl3 and CF4 are introduced into the reaction chamber. The second Bragg reflective layer is etched according to the photoresist pattern of the bevel edge so that the bevel edge of the second Bragg reflective layer is etched downward to form an acute edge. The two ends of the second Bragg reflective layer 32 are respectively recessed into the two ends of the epitaxial layer 20, and the difference at one end is 2-4 μm.

[0089] The second Bragg reflector layer 32 is placed in a hydrofluoric acid solution with a concentration of 3%-20% and etched for 50-200 seconds to etch the third reflector sublayer 320 so that the length of the third reflector sublayer 320 etched away is 2-10 times the thickness of the third reflector sublayer 320.

[0090] Compared to existing technologies, the light-emitting diode (LED) with increased emission angle provided in this embodiment has the following advantages: The LED with increased emission angle provided by this invention includes a Bragg reflector layer comprising a first Bragg reflector layer and a second Bragg reflector layer. The first Bragg reflector layer is disposed on the epitaxial layer, and the second Bragg reflector layer is disposed on the first Bragg reflector layer. The length of the first Bragg reflector layer is greater than the length of the second Bragg reflector layer. The edge of the first Bragg reflector layer is not covered by the edge of the second Bragg reflector layer. Light refracted to the edge by the first Bragg reflector layer will exit from the edge of the uncovered second Bragg reflector layer, changing the light emission path at the edge of the LED, thereby enhancing lateral emission and increasing the emission angle of the LED, i.e., increasing the emission area of ​​the LED. Furthermore, the second Bragg reflector layer is composed of several third and fourth reflector sublayers arranged in a second preset period. The length of the third reflector sublayer is less than the length of the fourth reflector sublayer. Light trapped within the second Bragg reflector layer is emitted laterally through the extended fourth reflector sublayer, further increasing the emission angle of the LED, reducing the number of LEDs in the display device, and achieving the requirements of a thinner and more energy-efficient display. This solves the common technical problem of Bragg reflectors restricting light emission from the edges of LEDs and affecting the light emission angle of LEDs.

[0091] Example 5

[0092] Please see Figure 5 The fifth embodiment of the present invention provides a method for fabricating a light-emitting diode with an increased light emission angle, the method comprising steps S10-S13:

[0093] Step S10: Provide a substrate;

[0094] The substrate is a sapphire substrate.

[0095] Step S11: An epitaxial layer and a Bragg reflective layer are sequentially grown on the substrate. The Bragg reflective layer includes a first Bragg reflective layer and a second Bragg reflective layer, or includes a second Bragg reflective layer. The first Bragg reflective layer is grown on the epitaxial layer, and the second Bragg reflective layer is grown on the first Bragg reflective layer or the epitaxial layer. The first Bragg reflective layer includes a first and a second reflective sublayer stacked alternately for a first preset period, and the second Bragg reflective layer includes a third and a fourth reflective sublayer stacked alternately for a second preset period.

[0096] An epitaxial layer is grown on a substrate. It should be noted that the epitaxial layer includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer to achieve the light emission of a light-emitting diode.

[0097] When the Bragg reflector layer includes a first Bragg reflector layer and a second Bragg reflector layer, the first Bragg reflector layer is grown on the epitaxial layer to reflect the light emitted from the epitaxial layer. The first Bragg reflector layer includes a first preset period of alternating stacked first and second reflector sub-layers, with the first preset period being 1-13. The length of the first Bragg reflector layer is equal to the length of the epitaxial layer, completely covering the epitaxial layer, protecting it, improving the reliability of the light-emitting diode, and preventing external impurities from entering the epitaxial layer and affecting its various performance characteristics.

[0098] Specifically, the temperature is set between 100-200℃, the evaporation rate is set to 5-20 A / s, and the evaporation thickness on the epitaxial layer is [missing information]. The SiO2 thin film layer is used as the first reflective sublayer.

[0099] Set the temperature between 100-200℃, the evaporation rate to 1-10 A / s, and the evaporation thickness on the first reflective sublayer to be [missing value]. The TiO2 thin film layer is used as the second reflective sublayer.

[0100] The first reflective sublayer and the second reflective sublayer are grown alternately in sequence according to the first preset cycle of 1-13.

[0101] Evaporation is a method of obtaining thin film materials by heating materials in a vacuum environment, causing them to vaporize and deposit them onto a substrate.

[0102] Subsequently, a second Bragg reflector layer is grown on the first Bragg reflector layer to reflect the light emitted from the epitaxial layer.

[0103] Set the temperature between 100-200℃ and the evaporation rate between 5-20 A / s. The thickness of the first Bragg reflective layer after growth is [missing value]. The SiO2 thin film layer is used as the third reflective sublayer.

[0104] Set the temperature between 100-200℃, the evaporation rate to 1-10 A / s, and the evaporation thickness on the third reflective sublayer to be [missing value]. The TiO2 thin film layer is used as the fourth reflective sublayer.

[0105] The third and fourth reflective sublayers are grown alternately in sequence according to the second preset cycle of 10-25.

[0106] When the Bragg reflector is only the second Bragg reflector, the second Bragg reflector includes a second preset period of alternately stacked third and fourth reflector sub-layers.

[0107] Specifically, the temperature is set between 100-200℃, the evaporation rate is set to 5-20 A / s, and the evaporation thickness on the epitaxial layer is [missing information]. The SiO2 thin film layer is used as the third reflective sublayer.

[0108] Set the temperature between 100-200℃, the evaporation rate to 1-10 A / s, and the evaporation thickness on the third reflective sublayer to be [missing value]. The TiO2 thin film layer is used as the fourth reflective sublayer.

[0109] The third and fourth reflective sublayers are grown alternately in sequence according to the second preset cycle of 10-25.

[0110] Step S12: Coat a photoresist layer on the second Bragg reflector layer, and expose, develop, harden and etch the photoresist layer so that the length of the second Bragg reflector layer is less than the length of the first Bragg reflector layer or the epitaxial layer.

[0111] Photoresist is a photoresist-resistant thin film material whose solubility changes upon exposure to specific light or radiation. Photoresists are classified into two main categories based on the image they form: positive and negative. In semiconductor processes, after exposure and development, the exposed portion of the photoresist dissolves, while the unexposed portion remains; in this case, the photoresist is positive. If the exposed portion remains while the unexposed portion dissolves, the photoresist is negative. In this embodiment, the photoresist layer is either positive or negative.

[0112] Furthermore, the angle at which the photoresist layer is formed can be varied by controlling the temperature of the photoresist hardening film. A higher hardening temperature results in a smaller photoresist angle, leading to a smaller morphology angle after etching. In this embodiment, the edge of the second Bragg reflective layer can be either a vertical edge or a beveled edge.

[0113] Specifically, a photoresist layer with a thickness of 2-15 μm is coated on the grown second Bragg reflector layer. The photoresist layer is exposed at an energy of 200-1200 MJ. A developer is sprayed to develop the photoresist layer. After development, the temperature is set between 20-150℃, and the photoresist is hardened for 50-200 seconds to form the photoresist pattern at the desired edge.

[0114] Ar, BCl3 and CF4 are introduced into the reaction chamber. The second Bragg reflective layer is etched according to the photoresist pattern of the required edge. The two ends of the second Bragg reflective layer are recessed into the two ends of the epitaxial layer, and the difference at one end is 2-4 μm.

[0115] It should be noted that the length of the first Bragg reflector or epitaxial layer is greater than the length of the second Bragg reflector. The edge of the first Bragg reflector or epitaxial layer is not covered by the edge of the second Bragg reflector. The light refracted to the edge by the first Bragg reflector or epitaxial layer will be emitted from the edge of the uncovered second Bragg reflector, changing the light emission path of the light-emitting diode edge, thereby enhancing lateral light emission and increasing the light emission angle of the light-emitting diode.

[0116] Step S13: Etch the second Bragg reflector layer so that the length of the third reflector sublayer is less than that of the fourth reflector sublayer.

[0117] In this design, the length of the third reflective sublayer is shorter than that of the fourth reflective sublayer. Light trapped within the second Bragg emitting layer is redirected through the extended fourth reflective sublayer, further increasing the emission angle of the light-emitting diodes (LEDs) and reducing the number of LEDs per unit emission area in the display device. This achieves the desired thinness and power efficiency for the display.

[0118] Specifically, the second Bragg reflector layer is placed in a hydrofluoric acid solution with a concentration of 3%-20% and etched for 50-200 seconds to etch the third reflector layer so that the length of the third reflector layer etched away is 2-10 times the thickness of the third reflector layer.

[0119] After etching, the second Bragg reflector layer is stripped of its photoresist. The photoresist layer covering the second Bragg reflector layer is dissolved with photoresist solvent to obtain a light-emitting diode that can increase the light emission angle.

[0120] Compared to existing technologies, the method for fabricating a light-emitting diode (LED) with an increased light emission angle provided in this embodiment offers the following advantages: By etching away a fixed length from the edge of the second Bragg reflector layer, the edge of the first Bragg reflector layer or epitaxial layer is not covered by the edge of the second Bragg reflector layer. Light refracted to the edge by the first Bragg reflector layer or epitaxial layer will then exit through the edge of the uncovered second Bragg emitter layer, altering the light emission path at the LED edge and thus enhancing lateral light emission. Simultaneously, a fixed length is etched away from the edge of the third reflector layer, with the length of the third reflector layer being less than that of the fourth reflector layer. Light trapped within the second Bragg emitter layer is then emitted laterally through the extended fourth reflector layer, further increasing the LED emission angle and reducing the number of LEDs in the display device, thus achieving the requirements of a thinner and more energy-efficient display. This solves the common technical problem of the Bragg reflector layer restricting light emission from the LED edge and affecting the LED emission angle.

[0121] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0122] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A light-emitting diode with an increased light emission angle, comprising a substrate, characterized in that, The light-emitting diode also includes: An epitaxial layer and a Bragg reflector layer are sequentially stacked on the substrate; The Bragg reflector layer includes a first Bragg reflector layer and a second Bragg reflector layer or includes a second Bragg reflector layer. The first Bragg reflector layer is disposed on the epitaxial layer, and the second Bragg reflector layer is disposed on the first Bragg reflector layer or the epitaxial layer. The length of the first Bragg reflector layer or the epitaxial layer is greater than the length of the second Bragg reflector layer. The first Bragg reflector layer includes a first and second reflector sublayers stacked alternately for a first preset period. The second Bragg reflector layer includes a third and fourth reflector sublayers stacked alternately for a second preset period. The length of the third reflector sublayer is less than the length of the fourth reflector sublayer. The two ends of the first Bragg reflector layer or the epitaxial layer extend beyond the two ends of the second Bragg reflector layer, with a difference of 2-4 μm at one end. The two ends of the third reflector sublayer are recessed into the two ends of the fourth reflector sublayer, with a difference of 2-10 times the thickness of the third reflector sublayer at one end.

2. The light-emitting diode with increased light emission angle according to claim 1, characterized in that, Both the first reflective sublayer and the third reflective sublayer are SiO2 thin film layers with a thickness of [missing information]. Both the second reflective sublayer and the fourth reflective sublayer are TiO2 thin film layers with a thickness of [missing information].

3. The light-emitting diode with increased light emission angle according to claim 1, characterized in that, The first preset period is 1-13, and the second preset period is 10-25.

4. The light-emitting diode with increased light emission angle according to claim 1, characterized in that, The thickness of the first Bragg reflector is 0.1-3 μm, and the thickness of the second Bragg reflector is 2-5 μm.

5. The light-emitting diode with increased light emission angle according to claim 1, characterized in that, The length of the first Bragg reflector layer is the same as the length of the epitaxial layer.

6. The light-emitting diode with increased light emission angle according to claim 1, characterized in that, The substrate is a sapphire substrate.

7. A method for fabricating a light-emitting diode with an increased light emission angle, characterized in that, The preparation method is used to prepare the light-emitting diode with increased light emission angle according to any one of claims 1-6, and the preparation method includes: Provide a substrate; An epitaxial layer and a Bragg reflective layer are sequentially grown on the substrate. The Bragg reflective layer includes a first Bragg reflective layer and a second Bragg reflective layer, or includes a second Bragg reflective layer. The first Bragg reflective layer is grown on the epitaxial layer, and the second Bragg reflective layer is grown on the first Bragg reflective layer or the epitaxial layer. The first Bragg reflective layer includes a first reflective sublayer and a second reflective sublayer stacked alternately for a first preset period, and the second Bragg reflective layer includes a third reflective sublayer and a fourth reflective sublayer stacked alternately for a second preset period. A photoresist layer is coated on the second Bragg reflector layer. The photoresist layer is exposed, developed, hardened and etched so that the length of the second Bragg reflector layer is less than the length of the first Bragg reflector layer or the epitaxial layer. The two ends of the first Bragg reflector layer or the epitaxial layer extend beyond the two ends of the second Bragg reflector layer, and the difference at one end is 2-4 μm. The second Bragg reflector layer is etched so that the length of the third reflector sublayer is less than that of the fourth reflector sublayer. The two ends of the third reflector sublayer are recessed into the two ends of the fourth reflector sublayer, and the difference at one end is 2-10 times the thickness of the third reflector sublayer.

8. The method for preparing a light-emitting diode with an increased light emission angle according to claim 7, characterized in that, The growth steps of the second Bragg reflector layer include: The second Bragg reflector layer is deposited on the first Bragg reflector layer or the epitaxial layer by vapor deposition; A photoresist layer with a thickness of 2-15 μm is coated on the second Bragg reflector layer. The photoresist layer is exposed to an energy of 200-1200 MJ. A developer is sprayed to develop the photoresist layer. After development, the temperature is set between 20-150°C, and the photoresist is hardened for 50-200 seconds. Ar, BCl3 and CF4 are introduced into the reaction chamber to etch the second Bragg reflector layer so that the length of the second Bragg reflector layer is less than the length of the first Bragg reflector layer or the epitaxial layer. The second Bragg reflector layer is placed in a hydrofluoric acid solution with a concentration of 3%-20% and etched for 50-200 seconds to make the length of the third reflector layer smaller than that of the fourth reflector layer.

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