Light emitting diode with enhanced lateral light extraction and method of making the same

Abstract

This disclosure provides a light-emitting diode (LED) with improved lateral light emission and its fabrication method, belonging to the field of optoelectronic manufacturing technology. The LED includes a substrate and a light-emitting structure. The light-emitting structure is located on a first surface of the substrate, and a refractive structure is disposed on a second surface of the substrate. The refractive structure is used to refract light incident from the second surface towards the refractive structure in a direction away from the normal. The first surface and the second surface are two opposite surfaces on the substrate. This disclosure can increase the lateral light emission of the LED and improve the light emission uniformity of the LED.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light-emitting diode with improved lateral light emission and its fabrication method. Background Technology

[0002] Light-emitting diodes (LEDs) are highly influential new products in the optoelectronics industry. They are characterized by their small size, long lifespan, rich and colorful colors, and low energy consumption. They are widely used in lighting, displays, signal lights, backlights, toys, and other fields.

[0003] In related technologies, light-emitting diodes typically include a substrate, an epitaxial layer, and electrodes stacked sequentially. Light emitted from the epitaxial layer is usually emitted through a transparent substrate.

[0004] Because LEDs emit light in a Lambertian pattern, with strong axial light and weak lateral light, this can easily lead to poor light emission uniformity. Summary of the Invention

[0005] This disclosure provides a method for enhancing the lateral light emission of a light-emitting diode (LED), thereby increasing the lateral light emission amount and improving the light emission uniformity of the LED. The technical solution is as follows:

[0006] This disclosure provides a light-emitting diode, which includes a substrate and a light-emitting structure. The light-emitting structure is located on a first surface of the substrate, and a refractive structure is provided on a second surface of the substrate. The refractive structure is used to bend light incident from the second surface toward the refractive structure in a direction away from the normal. The first surface and the second surface are two opposite surfaces on the substrate.

[0007] In one implementation of this disclosure, the refractive structure includes a first film layer and a second film layer sequentially stacked on the second surface, wherein the refractive index of the first film layer is higher than that of the second film layer, and the refractive index of the first film layer is not higher than that of the substrate.

[0008] In another implementation of the present disclosure, the second surface has a plurality of spaced grooves, the refractive structure corresponds one-to-one with the grooves, the first film layer is located on the inner wall of the groove, and the second film layer is located on the surface of the first film layer away from the groove.

[0009] In another implementation of this disclosure, the cross-section of the groove and the cross-section of the second film layer are both triangular in the direction perpendicular to the first surface.

[0010] In another implementation of the present disclosure, the second film layer includes a plurality of sub-film layers stacked sequentially, and the refractive index of each sub-film layer decreases sequentially in the direction away from the first film layer.

[0011] In another implementation of the present disclosure, the orthographic projection of the first film layer onto the second surface coincides with the second surface.

[0012] In another implementation of the present disclosure, the first film layer is an Al2O3 layer, and the second film layer is a SiO2 layer or a SiN layer.

[0013] This disclosure provides a method for fabricating a light-emitting diode, comprising: providing a substrate; forming a light-emitting structure on a first surface of the substrate; and fabricating a refractive structure on a second surface of the substrate, the refractive structure being used to cause light incident from the second surface to bend away from the normal when refracted, wherein the first surface and the second surface are two opposite surfaces on the substrate.

[0014] In another implementation of the present disclosure, forming a light-emitting structure on the first surface of the substrate includes: etching a plurality of spaced grooves on the second surface; forming a first film layer in each of the grooves, the first film layer covering the bottom of the groove; forming a second film layer on the surface of the first film layer in each of the grooves to obtain the refractive structure, wherein the refractive index of the first film layer is higher than the refractive index of the second film layer.

[0015] In another implementation of this disclosure, forming a light-emitting structure on the first surface of the substrate includes: forming a first film layer on the second surface, the first film layer covering the second surface; sequentially forming a plurality of stacked sub-film layers on the surface of the first film layer to obtain a second film layer, wherein when forming the sub-film layer, the flow ratio of SiH4 to NO2 in the nth sub-film layer is SiH4:NO2=[a+(1000-n)]:b, where 0<a<5000Sccm, 0<b<5000Sccm, 0<n<1000.

[0016] The beneficial effects of the technical solutions provided in this disclosure include at least the following:

[0017] The light-emitting diode (LED) provided in this embodiment includes a substrate and a light-emitting structure located on a first surface of the substrate. The light-emitting structure emits light and exits from the substrate. A refractive structure is also provided on a second surface of the substrate, wherein the refractive structure directs light incident perpendicularly to the first surface onto the refractive structure towards the edge of the substrate. Thus, when axial light emitted perpendicular to the substrate from the light-emitting structure is incident into the refractive structure, the refractive structure directs the light towards the edge of the substrate, converting more light into lateral light, thereby increasing the lateral light emission of the LED and improving the light emission uniformity of the LED. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of this disclosure;

[0020] Figure 2 This is a schematic diagram of the structure of a substrate according to an embodiment of this disclosure;

[0021] Figure 3 This is a schematic diagram of another light-emitting diode structure provided in an embodiment of this disclosure;

[0022] Figure 4 This is a flowchart of a method for fabricating a light-emitting diode provided in an embodiment of this disclosure.

[0023] The markings in the diagram are explained as follows:

[0024] 10. Substrate; 11. First surface; 110. Groove; 12. Second surface;

[0025] 20. Epitaxial layer; 21. First semiconductor layer; 22. Light-emitting layer; 23. Second semiconductor layer;

[0026] 30. Refractive structure; 31. First film layer; 32. Second film layer; 321. Sub-film layer;

[0027] 41. Passivation layer; 42. Transparent conductive layer; 43. Electrode; 44. Current blocking layer. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0029] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0030] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of this disclosure. Figure 1 As shown, the light-emitting diode includes a substrate 10 and a light-emitting structure. The light-emitting structure is located on the first surface 11 of the substrate 10. A refractive structure 30 is provided on the second surface 12 of the substrate 10. The refractive structure 30 is used to bend the light incident from the second surface 12 toward the refractive structure 30 in a direction away from the normal. The first surface 11 and the second surface 12 are two opposite surfaces on the substrate 10.

[0031] The light-emitting diode provided in this embodiment includes a substrate 10 and a light-emitting structure located on a first surface 11 of the substrate 10. The light-emitting structure emits light and exits from the substrate 10. A refractive structure 30 is also provided on a second surface 12 of the substrate 10. The refractive structure 30 is used to direct light from the light-emitting structure perpendicular to the first surface 11 to the edge of the substrate 10. Thus, when axial light emitted from the light-emitting structure perpendicular to the substrate 10 is incident into the refractive structure 30, the refractive structure 30 can direct the light to the edge of the substrate 10, allowing more light to be converted into lateral light, thereby increasing the lateral light emission of the light-emitting diode and improving the light emission uniformity of the light-emitting diode.

[0032] Alternatively, the substrate may be a sapphire substrate, a silicon substrate, or a silicon carbide substrate. The substrate may be a flat substrate or a patterned substrate.

[0033] As an example, in this embodiment of the disclosure, the substrate is a sapphire substrate. Sapphire substrates are a commonly used substrate, with mature technology and low cost. Specifically, it can be a patterned sapphire substrate or a flat sapphire substrate.

[0034] Optionally, the light-emitting structure may include an epitaxial layer 20 located on the first surface 11. The epitaxial layer 20 may include a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 stacked sequentially.

[0035] In this process, one of the first semiconductor layer 21 and the second semiconductor layer 23 can be the second semiconductor layer 23, and the other of the first semiconductor layer 21 and the second semiconductor layer 23 can be the first semiconductor layer 21.

[0036] For example, the first semiconductor layer 21 may be an n-type GaN layer.

[0037] For example, the light-emitting layer 22 may include alternately grown InGaN quantum well layers and GaN quantum barrier layers. The light-emitting layer 22 may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0038] For example, the second semiconductor layer 23 may be a p-type GaN layer.

[0039] Optionally, the first surface 11 of the substrate 10 may have multiple protrusions, forming a surface with multiple protrusions for the light-emitting structure. By providing multiple protrusions on the first surface 11 of the substrate 10 for growing the epitaxial layer 20, a patterned substrate 10 is formed, which is beneficial to improving the growth quality of the epitaxial layer 20.

[0040] like Figure 1 As shown, the light-emitting structure also includes a passivation layer 41 and two electrodes. The surface of the second semiconductor layer 23 on the epitaxial layer 20 has a recessed structure that exposes the first semiconductor layer 21. One electrode is located on the surface of the second semiconductor layer 23, and the other electrode is located in the recessed structure and on the surface of the first semiconductor layer 21.

[0041] The passivation layer 41 is located at least on the surface of the second semiconductor layer 23, within the recessed structure, and on the surface of the first semiconductor layer 21. The surface of the passivation layer 41 also has two vias that expose the two electrodes respectively.

[0042] This exposes the two electrodes outside the passivation layer 41, facilitating connection with an external power source and allowing the epitaxial layer 20 to emit light when energized.

[0043] In the example system, the passivation layer 41 can be a distributed Bragg reflection (DBR layer), which consists of multiple periodically alternating layers of SiO2 and TiO2. The number of periods in the DBR layer can be between 20 and 50. For example, the number of periods in the DBR layer is 32.

[0044] The thickness of the SiO2 layer in the DBR layer can be from 800 angstroms to 1200 angstroms, and the thickness of the TiO2 layer can be from 500 angstroms to 900 angstroms.

[0045] In addition to its passivation function, the DBR layer also reflects light emitted from the light-emitting layer 22 toward the DBR layer back to the substrate, thereby improving the light emission effect.

[0046] For example, such as Figure 1 As shown, the light-emitting structure may also include a transparent conductive layer 42, which is located between the second semiconductor layer 23 and the electrode.

[0047] Optionally, the transparent conductive layer 42 can be an indium tin oxide (ITO) film. Indium tin oxide films have good transmittance and low resistivity. Using an indium tin oxide film as the transparent conductive layer 42 allows more light to pass through, thus ensuring optimal performance. Simultaneously, due to its low resistivity, it also facilitates carrier conduction, improving injection efficiency.

[0048] For example, when the transparent conductive layer 42 is an ITO layer, the thickness of the transparent conductive layer 42 can be from 50 angstroms to 5000 angstroms.

[0049] Optionally, the transparent conductive layer 42 can be a NiAu layer. The NiAu layer has good light transmittance, which not only facilitates carrier conduction but also effectively prevents the light from being blocked from the epitaxial layer 20.

[0050] For example, when the transparent conductive layer 42 is a NiAu layer, the thickness of the transparent conductive layer 42 may not exceed 20 angstroms.

[0051] For example, such as Figure 1 As shown, the light-emitting structure may further include a current-blocking layer 44, which is located between the transparent conductive layer 42 and the second semiconductor layer 23, and is positioned below the electrode 43. This prevents the current from directly extending to the region of the second semiconductor layer 23 below the electrode after the electrode is energized, thus facilitating the current to extend to other regions of the second semiconductor layer 23.

[0052] Figure 2 This is a schematic diagram of the structure of a substrate 10 according to an embodiment of this disclosure. For example... Figure 2 As shown, the refractive structure 30 includes a first film layer 31 and a second film layer 32 sequentially stacked on the second surface 12, wherein the refractive index of the first film layer 31 is higher than that of the second film layer 32.

[0053] See Figure 2The light path indicated by the middle arrow shows light rays perpendicular to the substrate 10 entering the substrate 10 from the light-emitting structure and exiting from the second surface 12 into the refractive structure 30. In the refractive structure 30, the refractive index of the first film layer 31 is higher than that of the second film layer 32. Because light rays with an incident angle less than 60° will experience large-angle exits in the low-refractive-index medium when entering from a high-refractive-index medium, light rays will exit at a large angle in the low-refractive-index medium. Figure 1 As shown in the diagram, θ2 > θ1; similarly, when light enters air from the second film layer 32, it travels from a high-refractive-index medium to a low-refractive-index medium, and the angle of refraction in air is also larger than the angle of incidence in the second film layer 32. Figure 1 As shown, θ3 > θ2. In this way, the refractive structure 30 directs the light towards the edge of the substrate 10, allowing more light to be converted into lateral light, thereby increasing the lateral light output of the light-emitting diode and improving the light output uniformity of the light-emitting diode.

[0054] The refractive index of the first film layer 31 is not higher than that of the substrate 10. In this way, when light enters the refractive structure from the substrate, the direction of the light will be bent once, which is conducive to the light exiting laterally towards the substrate.

[0055] Optionally, such as Figure 1 , 2 As shown, the second surface 12 has a plurality of spaced grooves 110, and the refractive structure 30 corresponds one-to-one with the grooves 110. The first film layer 31 is located on the inner wall of the groove 110, and the second film layer 32 is located on the surface of the first film layer 31 away from the groove 110.

[0056] The first film layer 31 covers the bottom of the entire groove 110, while the second film layer 32 is located on the first film layer 31. This prevents light from entering the groove 110 and directly entering the second film layer 32 in the refractive structure 30, so that the refractive structure 30 can refract the light towards the edge of the substrate 10.

[0057] Furthermore, by providing a groove 110 on the second surface 12 of the substrate 10 and placing the refractive structure 30 within the groove 110, the thickness of the substrate 10 is avoided, thus preventing an increase in the thickness of the light-emitting diode. Moreover, by placing the refractive structure 30 only within the groove 110, the amount of material used to fabricate the refractive structure 30 can be effectively reduced.

[0058] For example, such as Figure 1 , 2 As shown, in the direction perpendicular to the first surface 11, the cross-section of the groove 110 and the cross-section of the second film layer 32 are both triangular, and the first film layer 31 separates the groove 110 and the second film layer 32.

[0059] The groove 110 is set as a triangle so that vertically incident light is more easily reflected on the sidewalls of the groove 110, so as to refract the light toward the edge of the substrate 10.

[0060] Figure 3 This is a schematic diagram of another light-emitting diode structure provided in an embodiment of this disclosure. For example... Figure 3 As shown, the second film layer 32 includes a plurality of sub-film layers 321 stacked sequentially, and the refractive index of each sub-film layer 321 decreases sequentially in the direction away from the first film layer 31.

[0061] See Figure 3 As indicated by the middle arrow, light perpendicular to the substrate 10 enters the light-emitting structure from the substrate 10 and exits from the second surface 12 into the refractive structure 30. The refractive index of the first film layer 31 in the refractive structure 30 is higher than that of the second film layer 32, and the refractive index of each sub-film layer 321 in the second film layer 32 gradually decreases. When light enters a low-refractive-index medium from a high-refractive-index medium, light with an incident angle less than 60° will exit at a large angle in the low-refractive-index medium. Therefore, in addition to the increased exit angle when light travels from the first film layer 31 to the second film layer 32, the exit angle also gradually increases in the second film layer 32. This ensures that the refractive structure 30 directs light towards the edge of the substrate 10, allowing more light to be converted into lateral light, thereby increasing the lateral light output of the light-emitting diode and improving its light emission uniformity.

[0062] In this embodiment of the disclosure, such as Figure 3 As shown, the orthographic projection of the first film layer 31 onto the second surface 12 coincides with the second surface 12.

[0063] This way, the first film layer 31 and the second film layer 32 are completely covered on the first surface 11, ensuring that all vertically emitted light rays can be refracted towards the edge of the substrate 10 at the refractive structure 30, allowing more light to be converted into lateral light, thereby increasing the lateral light emission of the light-emitting diode and improving the light emission uniformity of the light-emitting diode.

[0064] Optionally, the first film layer 31 is an Al2O3 layer, and the second film layer 32 is a SiO2 layer or a SiN layer.

[0065] For example, the first film layer 31 is an Al2O3 layer with a refractive index of 1.76. The second film layer 32 is a SiO2 layer with a refractive index typically of 1.46. This creates a refractive structure 30 in which the refractive index of the first film layer 31 is higher than that of the second film layer 32.

[0066] Specifically, when the second film layer 32 consists of multiple sub-film layers 321, and the second film layer 32 is a SiO2 layer, each sub-film layer 321 is also a SiO2 layer. The refractive index of the SiO2 layer in each sub-film layer 321 can be adjusted by changing the process conditions.

[0067] Figure 4 This is a flowchart illustrating a method for fabricating a light-emitting diode (LED) according to an embodiment of this disclosure. Figure 4 As shown, the preparation method includes:

[0068] S11: Provide a substrate 10.

[0069] S12: A light-emitting structure is formed on the first surface 11 of the substrate 10.

[0070] S13: A refractive structure 30 is fabricated on the second surface 12 of the substrate 10.

[0071] The refractive structure 30 is used to bend light from the second surface 12 toward the refractive structure in a direction away from the normal. The first surface 11 and the second surface 12 are two opposite surfaces on the substrate 10.

[0072] The light-emitting diode (LED) fabricated by this method includes a substrate and a light-emitting structure located on a first surface of the substrate. The light-emitting structure emits light and exits from the substrate. A refractive structure is also present on a second surface of the substrate. This refractive structure directs light emitted from the light-emitting structure perpendicular to the first surface to the edge of the substrate. Thus, when axial light emitted from the light-emitting structure perpendicular to the substrate is incident into the refractive structure, the refractive structure directs the light towards the edge of the substrate, converting more light into lateral light. This increases the lateral light emission of the LED and improves its light emission uniformity.

[0073] In step S11, the substrate can be a sapphire substrate, a silicon substrate, or a silicon carbide substrate. The substrate can be a flat substrate or a patterned substrate.

[0074] As an example, in this embodiment of the disclosure, the substrate is a sapphire substrate. Sapphire substrates are a commonly used substrate, with mature technology and low cost. Specifically, it can be a patterned sapphire substrate or a flat sapphire substrate.

[0075] In this embodiment of the disclosure, the light-emitting structure may include an epitaxial layer 20, a transparent conductive layer 42, a passivation layer 41, and two electrodes 43.

[0076] like Figure 1 As shown, the epitaxial layer 20 is located on the first surface 11. The epitaxial layer 20 may include a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 stacked sequentially.

[0077] In this process, one of the first semiconductor layer 21 and the second semiconductor layer 23 can be the second semiconductor layer 23, and the other of the first semiconductor layer 21 and the second semiconductor layer 23 can be the first semiconductor layer 21.

[0078] For example, the first semiconductor layer 21 may be an n-type GaN layer.

[0079] For example, the light-emitting layer 22 may include alternately grown InGaN quantum well layers and GaN quantum barrier layers. The light-emitting layer 22 may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0080] For example, the second semiconductor layer 23 may be a p-type GaN layer.

[0081] like Figure 1 As shown, the light-emitting structure also includes a passivation layer 41 and two electrodes 43. The surface of the second semiconductor layer 23 on the epitaxial layer 20 has a recessed structure that exposes the first semiconductor layer 21. One electrode 43 is located on the surface of the second semiconductor layer 23, and the other electrode 43 is located in the recessed structure and on the surface of the first semiconductor layer 21.

[0082] The passivation layer 41 is located at least on the surface of the second semiconductor layer 23, within the recessed structure, and on the surface of the first semiconductor layer 21. The surface of the passivation layer 41 also has two vias that expose the two electrodes 43 respectively.

[0083] The process of preparing the light-emitting structure in step S12 may include the following steps:

[0084] In the first step, a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 are sequentially grown in the light-emitting region of the substrate 10 to form an epitaxial layer 20.

[0085] The first semiconductor layer 21 can be an n-type GaN layer.

[0086] For example, the thickness of the first semiconductor layer 21 can be from 1 μm to 5 μm, for example, the thickness of the first semiconductor layer 21 is 3 μm.

[0087] For example, the doping concentration of the n-type dopant in the first semiconductor layer 21 can be 10. 18 / cm 3 Up to 10 19 / cm 3 For example, a doping concentration of 5 × 10 18 / cm 3 .

[0088] The light-emitting layer 22 may include alternating InGaN quantum well layers and GaN quantum barrier layers. The light-emitting layer 22 may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0089] For example, the thickness of the InGaN quantum well can be from 2.5 nm to 3.5 nm, for example, the thickness of the InGaN quantum well is 3 nm; the thickness of the GaN quantum barrier can be from 9 nm to 20 nm, for example, the thickness of the GaN quantum barrier is 15 nm.

[0090] For example, the number of InGaN quantum well layers is the same as the number of GaN quantum barrier layers. The number of InGaN quantum well layers can be from 3 to 8, for example, the number of InGaN quantum well layers is 7.

[0091] The second semiconductor layer 23 can be a p-type GaN layer.

[0092] For example, the thickness of the second semiconductor layer 23 can be from 100 nm to 800 nm, for example, the thickness of the second semiconductor layer 23 is 450 nm.

[0093] For example, the doping concentration of the p-type dopant in the second semiconductor layer 23 can be 10. 18 / cm 3 Up to 10 20 / cm 3 For example, a doping concentration of 10 19 / cm 3 .

[0094] The second step is to etch a groove 110 on the surface of the second semiconductor layer 23 to expose the first semiconductor layer 21.

[0095] Specifically, this may include: forming a photoresist pattern on the second semiconductor layer 23 using photolithography; then, dry etching the second semiconductor layer 23 and the light-emitting layer 22 that are not covered by photoresist to form a groove 110 exposing the first semiconductor layer 21; and finally, removing the photoresist.

[0096] The third step is to sequentially form a current blocking layer 44 and a transparent conductive layer 42 on the surface of the second semiconductor layer 23.

[0097] The preparation of the transparent conductive layer 42 may include: first laying an indium tin oxide film, and then using photolithography and etching techniques to pattern the indium tin oxide film to obtain the transparent conductive layer 42.

[0098] The fourth step is to make two electrodes.

[0099] One electrode is connected to the transparent conductive layer 42, and the other electrode is located in the groove 110 and connected to the first semiconductor layer 21.

[0100] Optionally, both electrodes comprise one or more of the following metals: gold (Au), aluminum (Al), nickel (Ni), platinum (Pt), chromium (Cr), and titanium (Ti).

[0101] The fifth step is to form a passivation layer 41 in the second semiconductor layer 23, in the groove 110 and on the first semiconductor layer 21.

[0102] The passivation layer 41 is located at least on the surface of the second semiconductor layer 23, within the recessed structure, and on the surface of the first semiconductor layer 21. The surface of the passivation layer 41 also has two vias that expose the two electrodes respectively.

[0103] For example, the passivation layer 41 may be a SiO2 layer.

[0104] The process of forming the passivation layer 41 may include: first laying a SiO2 layer, and then using photolithography and etching techniques to pattern the SiO2 layer to obtain the passivation layer 41.

[0105] In preparation Figure 1 , Figure 2 When the light-emitting diode is shown, step S13 may include the following steps:

[0106] The first step is to etch a plurality of spaced grooves 110 on the second surface 12.

[0107] Specifically, a dry etching method can be used to form a groove 110 on the second surface 12.

[0108] The second step is to form a first film layer 31 in each groove 110, and the first film layer 31 covers the bottom of the groove 110.

[0109] The third step is to form a second film layer 32 on the surface of the first film layer 31 in each groove 110 to obtain the refractive structure 30.

[0110] The refractive index of the first film layer 31 is higher than that of the second film layer 32.

[0111] For example, the first film layer 31 is an Al2O3 layer, and the second film layer 32 is a SiO2 layer or a SiN layer.

[0112] In preparation Figure 3 When the light-emitting diode is shown, step S13 may include the following steps:

[0113] The first step is to form a first film layer 31 on the second surface 12.

[0114] The first film layer 31 covers the second surface 12.

[0115] The second step involves sequentially forming multiple stacked sub-film layers 321 on the surface of the first film layer 31 to obtain the second film layer 32.

[0116] In this embodiment of the disclosure, the second film layer may be a SiO2 layer.

[0117] When forming the sub-film layer, the flow ratio of SiH4 to NO2 in the nth sub-film layer is SiH4:NO2=[a+(1000-n)]:b, where 0<a<5000Sccm, 0<b<5000Sccm, and 0<n<1000.

[0118] This allows for the formation of sub-films with gradually decreasing refractive index by gradually reducing the proportion of SiH4.

[0119] The above is not intended to limit this disclosure in any way. Although this disclosure has been disclosed above through embodiments, it is not intended to limit this disclosure. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this disclosure. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this disclosure without departing from the content of the technical solution of this disclosure shall still fall within the scope of the technical solution of this disclosure.

Claims

1. A light-emitting diode, characterized in that, The light-emitting diode includes a substrate (10) and a light-emitting structure. The light-emitting structure is located on the first surface (11) of the substrate (10). The light-emitting structure includes an epitaxial layer (20). The epitaxial layer (20) includes a first semiconductor layer (21), a light-emitting layer (22), and a second semiconductor layer (23) stacked sequentially on the first surface (11). A refractive structure (30) is provided on the second surface (12) of the substrate (10). The refractive structure (30) is used to bend light incident from the second surface (12) toward the refractive structure (30) in a direction away from the normal when refracted. The first surface (11) and the second surface (12) are two opposite surfaces on the substrate (10). The refractive structure (30) includes a first film layer (31) and a second film layer (32) sequentially stacked on the second surface (12). The refractive index of the first film layer (31) is higher than that of the second film layer (32), and the refractive index of the first film layer (31) is not higher than that of the substrate (10). The second surface (12) has a plurality of spaced grooves (110), the refractive structure (30) corresponds one-to-one with the grooves (110), the first film layer (31) is located on the inner wall of the groove (110) and covers the bottom of the groove (110), the first film layer (31) in adjacent grooves (110) is not connected, the second film layer (32) is located on the surface of the first film layer (31) away from the groove (110), the surface of the second film layer (32) away from the light-emitting structure is flush with the second surface (12), and the second film layer (32) in adjacent grooves (110) is not connected; The second film layer (32) includes a plurality of sub-film layers (321) stacked sequentially, and the refractive index of each sub-film layer (321) decreases sequentially in the direction away from the first film layer (31).

2. The light-emitting diode according to claim 1, characterized in that, In the direction perpendicular to the first surface (11), the cross-section of the groove (110) and the cross-section of the second film layer (32) are both triangular.

3. The light-emitting diode according to claim 2, characterized in that, The orthographic projection of the first film layer (31) onto the second surface (12) coincides with the second surface (12).

4. The light-emitting diode according to any one of claims 1 to 3, characterized in that, The first film layer (31) is an Al2O3 layer, and the second film layer (32) is a SiO2 layer or a SiN layer.

5. A method for fabricating a light-emitting diode, characterized in that, The preparation method includes: Provide a substrate; A light-emitting structure is formed on a first surface of the substrate. The light-emitting structure includes an epitaxial layer, which includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer sequentially stacked on the first surface. A refractive structure is formed on the second surface of the substrate. The refractive structure is used to bend light incident from the second surface toward the refractive structure away from the normal. The first surface and the second surface are two opposite surfaces on the substrate. Forming the refractive structure includes: etching a plurality of spaced grooves on the second surface; forming a first film layer in each groove, the first film layer covering the bottom of the groove; forming a second film layer on the surface of the first film layer in each groove to obtain the refractive structure. The refractive index of the first film layer is higher than that of the second film layer, and the refractive index of the first film layer is not higher than that of the substrate. The second surface has a plurality of spaced grooves, and the refractive structure corresponds one-to-one with the grooves. The first film layer is located on the inner wall of the groove and covers the bottom of the groove. The first film layers in adjacent grooves are not connected. The second film layer is located on the surface of the first film layer away from the groove. The surface of the second film layer away from the light-emitting structure is flush with the second surface, and the second film layers in adjacent grooves are not connected. The second film layer includes a plurality of sub-film layers stacked sequentially, and the refractive index of each sub-film layer decreases sequentially in the direction away from the first film layer.

6. The preparation method according to claim 5, characterized in that, The formation of the light-emitting structure on the first surface of the substrate includes: A first film layer is formed on the second surface, and the first film layer covers the second surface. Multiple stacked sub-membrane layers are sequentially formed on the surface of the first membrane layer to obtain the second membrane layer. When forming the sub-membrane layer, the flow ratio of SiH4 to NO2 in the nth sub-membrane layer is SiH4:NO2=[a+(1000-n)]:b, where 0<a<5000Sccm, 0<b<5000Sccm, and 0<n<1000.

Images