Light emitting diode and light emitting device

Abstract

The application provides a light emitting diode and a light emitting device. An active layer in an epitaxial structure of the light emitting diode of the application comprises a first sequence and a second sequence, the In content in the first sequence and the second sequence is different, specifically, the first In content difference of the first potential well layer and the first potential barrier layer in the first sequence, and the second In content difference of the second potential well layer and the second potential barrier layer in the second sequence, the second In content difference is greater than the first In content difference. By setting the active layer to comprise two sequences with different In content, the electric field and the compressive stress in the quantum well are changed, so that the highest point and the lowest point of the electric potential in the quantum well are inhibited, which is helpful to obtain a lower wavelength half-width characteristic after the free carrier is injected into the quantum well, when the current fluctuates within a certain range, the degree of wavelength shift of the light radiated by the active layer (quantum well) is obviously reduced, and the display effect of the light emitting diode is obviously improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a light-emitting diode and a light-emitting device. Background Technology

[0002] Light-emitting diodes (LEDs) have advantages such as high luminous intensity, high efficiency, small size, and long lifespan, and are considered to be one of the most promising light sources today.

[0003] Light-emitting diodes (LEDs) utilize semiconductor materials to form a light-emitting epitaxial layer, converting electrical energy into light energy. Gallium nitride (GaN)-based materials possess excellent properties such as a wide direct bandgap, strong chemical bonds, high temperature resistance, and corrosion resistance, making them considered the most promising light source today. They are gradually replacing traditional lighting sources and are increasingly widely used in full-color large-screen displays, LCD (Liquid Crystal Display) backlights, signal lights, and other lighting applications. With the gradual maturation of LEDs, especially Micro-LEDs, the demand for the half-width at half-width (WWHM) emission wavelength characteristics of LEDs will further increase in fields with high display requirements.

[0004] When forming the light-emitting epitaxial layer, the active layer is usually a stack of single components. This makes it impossible to control the half-width at half-maximum (WWHM) of the emission wavelength of the light-emitting diode (LED), resulting in large fluctuations in the WWHM and affecting the display effect in subsequent applications. Therefore, to address the above technical problem, it is necessary to provide a structure that can control the WWHM of the light-emitting diode. Summary of the Invention

[0005] In view of the defects and deficiencies existing in the prior art, the purpose of this application is to provide a light-emitting diode and a light-emitting device, which effectively controls the wavelength half-width characteristics of the light-emitting diode and improves the light-emitting effect by designing the active layer to include a first sequence and a second sequence with different In component contents.

[0006] According to one aspect of this application, a light-emitting diode is provided, comprising at least an epitaxial structure, wherein the epitaxial structure includes at least a first semiconductor layer, an active layer, and a second semiconductor layer sequentially stacked; wherein...

[0007] The active layer includes multiple periodic quantum well structures. In the direction from the first semiconductor layer to the second semiconductor layer, the active layer includes a first sequence and a second sequence formed on the first sequence. The first sequence includes a periodically stacked first potential well layer and a first potential barrier layer, and the second sequence includes a periodically stacked second potential well layer and a second potential barrier layer.

[0008] The first potential well layer and the second potential well layer are In-containing nitride material layers. The first potential well layer and the first barrier layer have a first In content difference, and the second potential well layer and the second barrier layer have a second In content difference, and the second In content difference is greater than the first In content difference.

[0009] According to one aspect of this application, a light-emitting diode is also provided, which includes at least an epitaxial structure, the epitaxial structure comprising at least a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially; wherein,

[0010] The active layer includes multiple periodic quantum well structures. In the direction from the first semiconductor layer to the second semiconductor layer, the active layer includes a first sequence and a second sequence formed on the first sequence. The first sequence includes a periodically stacked first potential well layer and a first potential barrier layer, and the second sequence includes a periodically stacked second potential well layer and a second potential barrier layer.

[0011] The first potential well layer and the first potential barrier layer have a first bandgap difference, the second potential well layer and the second potential barrier layer have a second bandgap difference, and the second bandgap difference is greater than the first bandgap difference.

[0012] According to one aspect of this application, a display device is also provided, the display device including a light source, the light source being a light-emitting diode provided in this application.

[0013] Compared with the prior art, the light-emitting diode and light-emitting device provided in this application have at least the following beneficial effects:

[0014] The active layer in the epitaxial structure of this application includes a first sequence and a second sequence, with different In content in the first and second sequences. Specifically, the first sequence has a first In content difference between the first potential well layer and the first barrier layer, while the second sequence has a second In content difference between the second potential well layer and the second barrier layer, and the second In content difference is greater than the first In content difference. By setting the active layer to include two sets of sequences with different In content, the electric field and compressive stress within the quantum well are changed. In particular, by setting the first sequence with a smaller In content difference between the potential well layer and the barrier layer near the first semiconductor layer, the highest and lowest points of the potential within the quantum well are suppressed. This helps to obtain a lower wavelength half-width characteristic after free carrier injection into the quantum well. When the current fluctuates within a certain range, the wavelength shift of the light emitted by the active layer (quantum well) is significantly reduced, and the display effect of the light-emitting diode is significantly improved. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships in the drawings described below are based on the direction in which the components are drawn in the figures.

[0016] For convenience or clarity, the thickness and dimensions of each layer shown in the figure may be exaggerated, omitted, or drawn approximations. Additionally, the dimensions of the light-emitting devices do not perfectly reflect their actual dimensions.

[0017] Figure 1 The diagram shown is a schematic diagram of the epitaxial structure of the light-emitting diode provided in Embodiment 1 of this application.

[0018] Figure 2 Displayed as Figure 1 A schematic diagram of the active layer structure.

[0019] Figure 3 The diagram shows the In content of the active layer of the light-emitting diode provided in Example 1.

[0020] Figure 4 The diagram shows a comparison of the potential of the active layer of the light-emitting diode (sample) provided in Example 1 with that of a light-emitting diode with a quantum well having a single set of layers in the prior art (comparative example).

[0021] Figure 5 The graph shows a comparison of the quantum efficiency of the light-emitting diode (sample) provided in Example 1 with that of a light-emitting diode with a single-layer quantum well in the prior art (control example).

[0022] Figure 6 The diagram shows a comparison of the wavelength half-width characteristics of the light-emitting diode (sample) provided in Example 1 and a light-emitting diode with a single-layer quantum well in the prior art (control example).

[0023] Figure 7 The image shown is a blue shift comparison diagram of the light-emitting diode (sample) provided in Example 1 and a light-emitting diode with a single set of layers in the prior art (control example).

[0024] Figure 8 The diagram shown is a schematic diagram of the band gap between the potential well layer and the potential barrier layer in the active layer of the light-emitting diode provided in the embodiment of this application.

[0025] Figure 9 The diagram shown is a schematic diagram of the light-emitting device provided in Embodiment 3 of this application.

[0026] List of reference numerals in the attached diagram:

[0027] 10. Epitaxial structure; 11. First semiconductor layer; 111. Undoped GaN layer; 112. N-type GaN layer; 12. Active layer; 121. First sequence; 1211. First potential well layer; 1212. First barrier layer; 122. Second sequence; 1221. Second potential well layer; 1222. Second barrier layer; 13. Second semiconductor layer; 131. Electron blocking layer; 132. P-type GaN layer; 14. First surface; 15. Second surface.

[0028] 200. Light-emitting device; 201. Circuit board; 202. Light source. Detailed Implementation

[0029] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0030] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Although the illustrations only show components related to the present invention and are not drawn according to the actual number, shape and size of the components, the shape, quantity, positional relationship and proportion of each component can be arbitrarily changed under the premise of realizing the technical solution of this invention, and the layout of the components may also be more complex.

[0031] To address the shortcomings of existing light-emitting diodes (LEDs) in terms of wavelength half-width and blue shift, this application optimizes the epitaxial structure design of the LED. One embodiment of this application provides an LED comprising at least one epitaxial structure, which includes at least a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially.

[0032] The active layer includes a multi-period quantum well structure. In the direction from the first semiconductor layer to the second semiconductor layer, the active layer includes a first sequence and a second sequence formed on the first sequence. The first sequence includes a periodically stacked first potential well layer and a first potential barrier layer, and the second sequence includes a periodically stacked second potential well layer and a second potential barrier layer.

[0033] The first potential well layer and the second potential well layer are In-containing nitride material layers. The first potential well layer and the first barrier layer have a first In content difference, and the second potential well layer and the second barrier layer have a second In content difference, and the second In content difference is greater than the first In content difference.

[0034] By setting the active layer to include two sequences with different In content, the electric field and compressive stress in the quantum well are changed. In particular, the first sequence with a smaller difference in In content between the potential well layer and the barrier layer is set near the first semiconductor layer, so that the highest and lowest points of the potential in the quantum well are suppressed. This helps to obtain a lower wavelength half-width characteristic after free carriers are injected into the quantum well. When the current fluctuates within a certain range, the wavelength shift of the light emitted by the active layer (quantum well) is significantly reduced, and the display effect of the light-emitting diode is significantly improved.

[0035] Optionally, the first sequence includes a first potential well layer and a first potential barrier layer with x cycles, and the second sequence includes a second potential well layer and a second potential barrier layer with y cycles, where x and y are both integers greater than or equal to 1, and y ≥ x.

[0036] Since electron mobility is usually much higher than hole mobility, the light-emitting region of a light-emitting diode is mainly close to the active region on the side of the second semiconductor layer. By setting the second sequence, which is the main light-emitting region, to have a larger number of cycles and the first sequence, which is used to regulate the half-width characteristic of the emission wavelength, to have a smaller number of cycles, the luminous efficiency of the light-emitting diode can be improved without affecting the display performance.

[0037] Optionally, in the first sequence, 1 ≤ x ≤ 15, and in the second sequence, 1 ≤ y ≤ 20.

[0038] Appropriate period number restrictions on the first and second sequences in the active layer can ensure the carrier concentration distribution in the active layer while reducing wavelength changes, suppressing wavelength blue shift, and improving display performance.

[0039] Optionally, the first potential well layer is Al a1 In b1 Ga (1-a1-b1) N layers, the second potential well layer is Al a2 In b2 Ga (1-a2-b2) There are N layers, where 0 < a1, a2 < 0.05, 0 < b1 < 0.3, 0 < b2 ≤ 0.3, and b1 < b2.

[0040] Furthermore, optionally, the first potential well layer is Al a1 In b1 Ga (1-a1-b1) N, the second potential well layer is Al a2 In b2 Ga (1-a2-b2) There are N layers, where 0 < a1, a2 ≤ 0.02, 0 < b1 ≤ 0.27, 0 < b2 ≤ 0.3, and b1 < b2.

[0041] The limitations on the materials and In content of the first and second potential well layers ensure that the active layer can radiate light of the required wavelength. At the same time, the difference in In content between the first and second potential well layers can effectively suppress the polarization electric field and facilitate the change of compressive stress in the active layer. This reduces the compressive stress in the active layer, which is beneficial for improving the half-width characteristic of the wavelength and suppressing the blue shift of the wavelength.

[0042] Optionally, the first barrier layer is Al. c1 In d1 Ga (1-c1-d1) N layers, the second barrier layer is Al c2 In d2 Ga (1-c2-d2) N layers, where 0≤c1≤1, 0≤d1≤1, 0≤c2≤1, 0≤d2≤1.

[0043] The choice of materials for the first and second barrier layers ensures that the active layer can radiate the desired wavelength.

[0044] Optionally, the first potential well layer and the second potential well layer are made of the same material.

[0045] Optionally, the first barrier layer and the second barrier layer are made of the same material.

[0046] Using the same materials for the potential well and barrier layers can reduce the difficulty of the process and also help improve the wavelength uniformity of the active layer radiation, achieving more consistent light emission characteristics, thereby improving the reliability and yield of the device.

[0047] Optionally, the thickness of the first sequence is less than or equal to the thickness of the second sequence.

[0048] By making the second sequence, which serves as the main light-emitting area, thicker, it is possible to improve display performance while ensuring the luminous efficiency of the light-emitting diodes.

[0049] Optionally, the thickness of the first sequence is between Between the ranges, the thickness of the second sequence is between Between ranges.

[0050] The thickness constraint of the first sequence ensures that it can significantly suppress the polarization electric field and stress of the active layer, which helps to improve the half-width characteristic of the wavelength and reduce the blue shift. The thickness constraint of the second sequence ensures the optical radiation of the active layer.

[0051] Optionally, the band gap of the first potential well layer is larger than the band gap of the second potential well layer.

[0052] The selection of materials for the potential well layers in the first and second sequences, as well as the limitation of the In content therein, can make the band gap of the first potential well layer in the first sequence larger than that of the second potential well layer in the second sequence. This can block hole injection into other non-light-emitting regions besides the second sequence, allowing more holes to be injected into the second sequence, which is the main light-emitting region, thereby improving the internal quantum efficiency of the light-emitting diode and increasing its brightness.

[0053] According to another embodiment of this application, a light-emitting diode is provided, which includes at least one epitaxial structure, the epitaxial structure comprising at least a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially; wherein...

[0054] The active layer includes multiple periodic quantum well structures. In the direction from the first semiconductor layer to the second semiconductor layer, the active layer includes a first sequence and a second sequence formed on the first sequence. The first sequence includes a periodically stacked first potential well layer and a first potential barrier layer, and the second sequence includes a periodically stacked second potential well layer and a second potential barrier layer.

[0055] The first potential well layer and the first potential barrier layer have a first bandgap difference, the second potential well layer and the second potential barrier layer have a second bandgap difference, and the second bandgap difference is greater than the first bandgap difference.

[0056] By setting the active layer to include two sets of sequences with different band gaps, the highest and lowest points of the potential in the quantum well are suppressed, which helps to obtain a lower wavelength half-width characteristic after free carriers are injected into the quantum well. When the current fluctuates within a certain range, the wavelength shift of the light emitted by the active layer (quantum well) is significantly reduced, and the display effect of the light-emitting diode is significantly improved.

[0057] Optionally, the first sequence includes a first potential well layer and a first potential barrier layer with x cycles, and the second sequence includes a second potential well layer and a second potential barrier layer with y cycles, where x and y are both integers greater than or equal to 1, and y ≥ x.

[0058] Appropriate period number restrictions on the first and second sequences in the active layer can ensure the carrier concentration distribution in the second sequence, which serves as the main light-emitting region in the active layer, while reducing wavelength changes, suppressing wavelength blue shift, and improving display performance.

[0059] Optionally, the first potential well layer is Al a1 In b1 Ga (1-a1-b1) N layers, the second potential well layer is Al a2 In b2 Ga (1-a2-b2) There are N layers, where 0 < a1, a2 < 0.05, 0 < b1 < 0.3, 0 < b2 ≤ 0.3, and b1 < b2.

[0060] Optionally, the first barrier layer is Al. c1 In d1 Ga (1-c1-d1) N layers, the second barrier layer is Al c2 In d2 Ga (1-c2-d2) N layers, where 0≤c1≤1, 0≤d1≤1, 0≤c2≤1, 0≤d2≤1.

[0061] The choice of materials for the potential well layer and the barrier layer can ensure that the active layer can radiate the desired wavelength. On the other hand, the difference in In content between the first and second potential well layers can effectively suppress the polarization electric field and facilitate the change of compressive stress in the active layer, thereby alleviating the compressive stress in the active layer, which is beneficial to improving the half-width characteristic of the wavelength and suppressing the blue shift of the wavelength.

[0062] Optionally, the thickness of the first sequence is less than or equal to the thickness of the second sequence.

[0063] By making the second sequence, which serves as the main light-emitting area, thicker, it is possible to improve display performance while ensuring the luminous efficiency of the light-emitting diodes.

[0064] Optionally, the band gap of the first potential well layer is larger than the band gap of the second potential well layer.

[0065] It can block hole injection into non-light-emitting regions other than the second sequence which is the main light-emitting region, thereby improving the internal quantum efficiency of the light-emitting diode and increasing the brightness of the light-emitting diode.

[0066] Optionally, the side length of the light-emitting diode is less than or equal to 100 μm.

[0067] Optionally, the emission wavelength of the active layer is between 500 nm and 570 nm.

[0068] Among the light-emitting diodes of the aforementioned size and radiating wavelength range, the requirement for the half-width characteristic of the emission wavelength of the light-emitting diode will be further increased.

[0069] Another embodiment of this application provides a light-emitting device, which includes a light-emitting light source, wherein the light-emitting light source is a light-emitting diode provided in this application.

[0070] The light-emitting device has the aforementioned light-emitting diode improved in this application, and therefore also has a good light-emitting effect.

[0071] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0072] The composition and dopants of each layer of the LED in this application can be analyzed using any suitable method, such as secondary ion mass spectrometry (SIMS). The thickness of each layer of the LED in this application can be analyzed using any suitable method, such as transmission electron microscopy (TEM) or scanning electron microscopy (SEM), in conjunction with, for example, the depth positions of each layer on a SIMS image.

[0073] Example 1

[0074] This embodiment provides a light-emitting diode (LED) that includes at least one epitaxial structure, which radiates light of a certain wavelength under the influence of an electric current. For example... Figure 1 As shown, the epitaxial structure 10 has a first surface 14 and a second surface 15 opposite to each other. In the direction from the first surface 14 to the second surface 15, the epitaxial structure 10 includes a first semiconductor layer 11, an active layer 12 and a second semiconductor layer 13 stacked sequentially.

[0075] See also Figure 1 The first semiconductor layer 11 and the second semiconductor layer 13 are semiconductor layers with opposite conductivity types. For example, they can provide electrons or holes by n-type doping or p-type doping, respectively. The n-type semiconductor layer can be doped with n-type dopants such as Si, Ge, or Sn, and the p-type semiconductor layer can be doped with p-type dopants such as Mg, Zn, Ca, Sr, C, or Ba. When the first semiconductor layer 11 is an n-type semiconductor, the second semiconductor layer 13 is a p-type semiconductor layer; when the first semiconductor layer 11 is a p-type semiconductor layer, the second semiconductor layer 13 is correspondingly an n-type semiconductor layer. The first semiconductor layer 11, the active layer 12, and the second semiconductor layer 13 can be formed from materials such as gallium nitride, aluminum gallium nitride, aluminum indium phosphide, aluminum gallium indium phosphide, gallium arsenide, or aluminum gallium arsenide. This embodiment uses an n-type semiconductor layer as an example for detailed description.

[0076] Each material layer in the epitaxial structure 10 can be formed using methods such as Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), Epitaxy Growth Technology, and Atomic Layer Deposition (ALD). The epitaxial structure 10 is a semiconductor material capable of providing conventional radiation such as ultraviolet, blue, green, yellow, red, and infrared light. By adjusting the composition ratio of the semiconductor material in the active layer 12, light of the target wavelength is emitted. For example, a gallium nitride-based epitaxial structure doped with elements such as aluminum and indium mainly provides radiation in the 200nm–570nm wavelength range; or an aluminum gallium indium phosphide-based or aluminum gallium arsenide-based epitaxial structure mainly provides radiation in the 550nm–950nm wavelength range. This embodiment provides an example of a GaN-based epitaxial structure 10 doped with elements such as aluminum and indium, with an emission wavelength between 200nm and 600nm, and further between 500nm and 570nm. In an optional embodiment, the side length of the light-emitting diode 100 is less than or equal to 100 μm. For light-emitting diodes of the above dimensions and radiating wavelength ranges, the requirement for the emission wavelength half-width characteristic of the light-emitting diode is further increased.

[0077] Reference Figure 1 The first semiconductor layer 11 includes a stacked undoped GaN layer 111 and an N-type GaN layer 112. During the growth of the epitaxial structure 10, the undoped GaN layer 1110 can reduce the lattice mismatch caused by the difference in lattice constants between the growth substrate and the N-type GaN layer 112, and the undoped GaN layer 111 can enhance the crystallinity of the epitaxially grown semiconductor layer, which is beneficial to improving the crystal quality of the epitaxial structure 10. Preferably, the growth temperature of the undoped GaN layer 111 and the N-type GaN layer 112 can be between 1000°C and 1200°C, the thickness of the first semiconductor layer 11 is between 1.5 μm and 4.5 μm, wherein the thickness of the N-type GaN layer 112 can be between 1.0 μm and 3.0 μm, and the N-type dopant in the N-type GaN layer 112 is, for example, Si, wherein the Si doping concentration is 1e18 cm⁻¹. -3 ~3e19cm -3 .

[0078] like Figure 1 As shown, the active layer 12 is formed above the N-type GaN layer of the first semiconductor layer 11. In this embodiment, the active layer 12 includes a first sequence 121 formed above the first semiconductor layer 11 and a second sequence 122 formed above the first sequence 121. Each sequence includes a periodically stacked potential well layer and a potential barrier layer. Figure 2As shown, the first sequence 121 includes a periodically stacked first potential well layer 1211 and a first potential barrier layer 1212, and the second sequence 122 includes a periodically stacked second potential well layer 1221 and a second potential barrier layer 1222. In this embodiment, the first potential well layer 1211 and the second potential well layer 1221 are In-containing nitride material layers, such as... Figure 3 As shown, the first potential well layer 1211 and the first barrier layer 1212 have a first In content difference, and the second potential well layer 1221 and the second barrier layer 1222 have a second In content difference, and the second In content difference is greater than the first In content difference. By setting the active layer to include two sets of sequences with different In contents, especially setting the first sequence with a smaller In content difference between the potential well layer and the barrier layer near the first semiconductor layer, the highest and lowest points of the potential in the quantum well are suppressed. This helps to obtain a lower wavelength half-width characteristic after free carriers are injected into the quantum well. When the current fluctuates within a certain range, the wavelength shift of the light emitted by the active layer (quantum well) is significantly reduced, and the display effect of the light-emitting diode is significantly improved.

[0079] In an optional embodiment, the first sequence 121 comprises a first potential well layer 1211 and a first potential barrier layer 1212 with x periods, and the second sequence 122 comprises a second potential well layer 1221 and a second potential barrier layer 1222 with y periods, where x and y are both integers greater than or equal to 1, and y ≥ x. Further, in the first sequence 121, 1 ≤ x ≤ 15, and further, 2 ≤ x ≤ 14. In the second sequence 122, 1 ≤ y ≤ 20, and further, 5 ≤ y ≤ 15. Further, for example, the first sequence 121 comprises a first potential well layer 1211 and a first potential barrier layer 1212 with 10 periods, and the second sequence 122 comprises a second potential well layer 1221 and a second potential barrier layer 1222 with 15 periods.

[0080] Since electron mobility is typically much higher than hole mobility, the light-emitting region of a light-emitting diode (LED) is mainly located near the active region on the side of the second semiconductor layer 12. By setting the second sequence 122, which serves as the main light-emitting region, to have a larger number of cycles, and setting the first sequence 121, which controls the half-width characteristic of the emission wavelength, to have a smaller number of cycles, the luminous efficiency of the LED is not affected while improving display performance. Appropriately limiting the number of cycles of the first sequence 121 and the second sequence 122 in the active layer 12 ensures the carrier concentration distribution in the active layer 12 while reducing wavelength variations, suppressing blue shift, and improving display quality.

[0081] In an optional embodiment, the thickness of the first sequence 121 is less than or equal to the thickness of the second sequence 122. By making the second sequence 122, which serves as the main light-emitting area, thicker, it is possible to improve display performance while ensuring the luminous efficiency of the light-emitting diode. In a specific embodiment, the thickness of the first sequence 121 is between... Between ranges, and further, between Between the ranges; the thickness of the second sequence 122 is between Between ranges, and further, between Within the range. The thickness constraint of the first sequence 121 ensures that it can significantly suppress the polarization electric field and stress of the active layer, which helps to improve the half-width characteristic of the wavelength and reduce the blue shift. The thickness constraint of the second sequence 122 ensures the optical radiation of the active layer.

[0082] In an optional embodiment, the first potential well layer 1211 is Al a1 In b1 Ga (1-a1-b1) N layers, the second potential well layer 1221 is Al a2 In b2 Ga (1-a2-b2) N layers, where 0 < a1, a2 < 0.05, 0 < b1 < 0.3, 0 < b2 ≤ 0.3, and b1 < b2. Further, 0 < a1, a2 ≤ 0.02; 0 < b2 ≤ 0.3; 0 < b1 ≤ 0.27, or 0.05 ≤ b1 ≤ 0.27, or 0.1 ≤ b1 ≤ 0.27.

[0083] The limitations on the materials and In content of the first potential well layer 1211 and the second potential well layer 1221 ensure that the active layer 12 can radiate light of the required wavelength. At the same time, the difference in In content between the first potential well layer 1211 and the second potential well layer 1221 can effectively suppress the polarization electric field and facilitate the change of compressive stress in the active layer 12, thereby alleviating the compressive stress in the active layer 12, which is beneficial to improving the half-width characteristic of the wavelength and suppressing the blue shift of the wavelength.

[0084] In an optional embodiment, the first barrier layer 1212 is Al c1 In d1 Ga (1-c1-d1) N layers, the second barrier layer 1222 is Al c2 In d2 Ga (1-c2-d2) N layers, where 0≤c1≤1, 0≤d1≤1, 0≤c2≤1, 0≤d2≤1. The material selection of the first barrier layer 1212 and the second barrier layer 1222 ensures that the active layer 12 can radiate the desired wavelength.

[0085] In an optional embodiment, the first potential well layer 1211 and the second potential well layer 1221 are made of the same material.

[0086] In an optional embodiment, the first barrier layer 1212 and the second barrier layer 1222 are made of the same material.

[0087] Using the same materials for the potential well and barrier layers can reduce the difficulty of the process and also help improve the wavelength uniformity of the active layer radiation, achieving more consistent light emission characteristics, thereby improving the reliability and yield of the device.

[0088] In an optional embodiment, the first well layer 1211 and the second well layer 1221 have the same material composition but different In content, while the first barrier layer 1212 and the second barrier layer 1222 have the same material composition and In content. For example, in one example, both the first well layer 1211 and the second well layer 1221 are InGaN layers, wherein the In content of the second well layer 1221 is higher than that of the first well layer 1211. In another example, both the first well layer 1211 and the second well layer 1221 are AlInGaN layers, wherein the In content of the second well layer 1221 is higher than that of the first well layer 1211.

[0089] In an optional embodiment, the first well layer 1211 and the second well layer 1221 have the same material composition but different In contents; the first barrier layer 1212 and the second barrier layer 1222 have the same material composition but also different In contents. For example, in one example, the first well layer 1211 and the second well layer 1221 are both InGaN layers, wherein the In content of the second well layer 1221 is higher than that of the first well layer 1211; the first barrier layer 1212 and the second barrier layer 1222 are both AlInGaN layers, wherein the In content of the second barrier layer 1222 is lower than that of the first barrier layer 1212. In another example, the first well layer 1211 and the second well layer 1221 are both InGaN layers, wherein the In content of the second well layer 1221 is higher than that of the first well layer 1211; the first barrier layer 1212 and the second barrier layer 1222 are both AlInGaN layers, wherein the In content of the second barrier layer 1222 is also higher than that of the first barrier layer 1212, but the difference in In content between the second barrier layer 1222 and the first barrier layer 1212 is smaller than the difference in In content between the second well layer 1221 and the first well layer 1211.

[0090] In optional embodiments, the first well layer 1211 and the second well layer 1221 have the same material composition but different In content, and the first barrier layer 1212 and the second barrier layer 1222 have different material compositions. For example, in one example, both the first well layer 1211 and the second well layer 1221 are InGaN layers, wherein the In content of the second well layer 1211 is higher than that of the first well layer 1221; the first barrier layer 1212 is an AlInGaN layer, and the second barrier layer 1222 is a GaN layer. In another example, both the first well layer 1211 and the second well layer 1221 are AlInGaN layers, wherein the In content of the second well layer 1221 is higher than that of the first well layer 1211; the first barrier layer 1212 is an InGaN layer, and the second barrier layer 1222 is a GaN layer. In another example, the first well layer 1211 and the second well layer 1221 are both InGaN layers, wherein the In content of the second well layer 1221 is higher than that of the first well layer 1211, the first barrier layer 1212 is an InGaN layer, and the second barrier layer 1222 is an AlInGaN layer.

[0091] In an optional embodiment, the first well layer 1211 and the second well layer 1221 have different material compositions and different In contents, while the first barrier layer 1212 and the second barrier layer 1222 have the same material composition and In content. For example, in one example, the first well layer 1211 is AlInGaN, the second well layer 1221 is InGaN, and the first barrier layer 1212 and the second barrier layer 1222 are AlInGaN layers with the same In content.

[0092] The limited In content in the first well layer 1211 and the second well layer 1221, compared to the active layers in the prior art, compresses the conduction band bottom and valence band top in the first well layer 121 of this embodiment. Therefore, the band gap of the first well layer 121 is larger than that of the second well layer 1221. Consequently, the first sequence 121 can block hole injection into non-light-emitting regions other than the second sequence 122, allowing more holes to be injected into the subsequent second sequence 122, thereby improving the internal quantum efficiency of the light-emitting diode (see reference). Figure 5 This increases the brightness of the LED.

[0093] See also Figure 1Above the active layer 12 is a second semiconductor layer 13, which includes a P-type GaN layer 132 that provides holes for the active layer 107. This P-type GaN layer 132 can be, for example, a Mg-doped AlGaN layer, an InAlGaN layer, or an AlGaN / GaN composite layer. To prevent electrons from diffusing from the first semiconductor layer 11 to the second semiconductor layer 13, an electron blocking layer 131 is formed between the P-type GaN layer 122 and the active layer 12. This electron blocking layer 131 can also be a P-type doped layer, such as at least one of a Mg-doped P-type AlGaN layer, a P-type InAlGaN layer, and a P-type AlGaN / GaN composite layer, and can be a superlattice structure. In an optional embodiment, the thickness of the P-type GaN layer is 30 nm to 500 nm, and the Mg doping concentration of the P-type GaN layer is 5e18 cm⁻¹. -3 ~5e20cm -3 The electron blocking layer 131 has a thickness of 30 nm to 80 nm and a Mg doping concentration of 5e18 cm⁻¹. -3 ~3.5e19cm -3 The second semiconductor layer 13 may also be configured with other layers besides those mentioned above; in addition, some layers may be omitted.

[0094] The above only exemplifies the layer structure of the epitaxial structure 10. It is understood that other functional layers can be formed during the actual epitaxial growth process.

[0095] The light-emitting diode in this embodiment also includes a substrate and an electrode structure. The electrode structure includes a first electrode electrically connected to the first semiconductor layer 11 and a second electrode electrically connected to the second semiconductor layer 13. The substrate can be a growth substrate suitable for growing epitaxial structures, such as a sapphire substrate, a silicon substrate, a germanium-silicon substrate, a silicon carbide substrate, etc. In an optional embodiment, in order to alleviate the problem of lattice quality degradation caused by defects such as lattice dislocations between the substrate and the epitaxial structure, a buffer layer is also formed between the substrate and the epitaxial structure 10 (specifically, the first semiconductor layer 11). The material of the buffer layer can be GaN, AlN, InAlGaN, or AlGaN, etc.

[0096] To verify the relevant features of the light-emitting diode in this embodiment, the light-emitting diode in this embodiment is compared with the light-emitting diodes in the prior art that form a single quantum well structure.

[0097] like Figure 4 As shown, the red dashed line represents the potential in the active layer 12 of the light-emitting diode in this embodiment, and the blue dashed line represents the potential in the active layer of a light-emitting diode in the prior art. Figure 4It is evident that, compared to the blue dashed line, the highest and lowest potential points shown by the red dashed line are suppressed. This contributes to obtaining a lower wavelength half-width characteristic after free carriers are injected into the active layer 12. Figure 5 As shown, the red line represents the current density and quantum efficiency curves of the light-emitting diode in this embodiment, while the blue line represents the current density and quantum efficiency curves of light-emitting diodes in the prior art. Compared to light-emitting diodes in the prior art, the light-emitting diode 100 of this embodiment has improved quantum efficiency within a specific current density range. That is, the light-emitting diode 100 of this application can have higher photoelectric efficiency, which helps to improve the brightness of the light-emitting diode 100.

[0098] To further verify the wavelength half-width characteristic and blue shift phenomenon of the light-emitting diode of this embodiment, the light-emitting diode 100 of this embodiment was compared with light-emitting diodes in the prior art. Specifically, as shown... Figure 6 and Figure 7 As shown, the red circles represent the voltage versus wavelength half-width or blue-shift plot of the LED in this embodiment, while the blue lines represent the voltage versus wavelength half-width or blue-shift plot of LEDs in the prior art. Figure 6 It can be seen that under a certain operating voltage, the half-width characteristic of the wavelength decreases significantly; for example... Figure 7 As shown, under a certain operating voltage, the wavelength blue shift characteristic of the light-emitting diode in this embodiment decreases significantly. It is evident that both the wavelength half-width characteristic and the blue shift characteristic of the light-emitting diode in this embodiment are limited to a certain extent. Therefore, in practical applications, when voltage (or current) fluctuations occur, the light-emitting diode 100 can still radiate light within a specific wavelength range, and its brightness will be improved to a certain extent.

[0099] Example 2

[0100] This embodiment also provides a light-emitting diode, which also includes at least an epitaxial structure that radiates light of a certain wavelength under the action of current.

[0101] The similarities with Example 1 will not be repeated here; the differences are as follows:

[0102] In this embodiment of the light-emitting diode, the active layer 12 includes multiple periodic quantum well structures. From the first semiconductor layer 11 to the second semiconductor layer 13, the active layer 12 includes a first sequence 121 and a second sequence 122 formed above the first sequence 121. The first sequence 121 includes a periodically stacked first potential well layer 1211 and a first barrier layer 1212, and the second sequence 122 includes a periodically stacked second potential well layer 1221 and a second barrier layer 1222. Figure 8 As shown, the first potential well layer 1211 and the first potential barrier layer 1212 have a first bandgap difference ( Figure 8The height difference between the two red lines), the second potential well layer 1221 and the second potential barrier layer 1222 have a second bandgap difference ( Figure 8 The height difference between the two blue lines in the middle), and the second band gap difference is greater than the first band gap difference.

[0103] By setting the active layer 12 to include two sets of sequences with different bandgap differences, the highest and lowest points of the potential within the quantum well are suppressed (see also [reference]). Figure 3 This helps to obtain a lower wavelength half-width characteristic after free carriers are injected into the quantum well. When the current fluctuates within a certain range, the wavelength shift of the light emitted by the active layer (quantum well) 12 is significantly reduced, and the display effect of the light-emitting diode is significantly improved.

[0104] In an optional embodiment, the first sequence 121 includes a first potential well layer 1211 and a first barrier layer 1212 with x periods, and the second sequence 122 includes a second potential well layer 1221 and a second barrier layer 1222 with y periods, where x and y are integers greater than or equal to 1, and y ≥ x. Appropriate period limits for the first and second sequences in the active layer can ensure the carrier concentration distribution in the second sequence, which serves as the main light-emitting region in the active layer, while reducing wavelength variations, suppressing wavelength blue shift, and improving display performance.

[0105] In an optional embodiment, the first potential well layer 1211 is Al a1 In b1 Ga (1-a1-b1) N layers, the second potential well layer 1221 is Al a2 In b2 Ga (1-a2-b2) N layers, where 0 < a1, a2 < 0.05, 0 < b1 < 0.3, 0 < b2 ≤ 0.3, and b1 < b2. Further, in an optional embodiment, 0 < a1, a2 ≤ 0.02, 0 < b2 ≤ 0.3; 0 < b1 ≤ 0.27, or 0.05 ≤ b1 ≤ 0.27, or 0.1 ≤ b1 ≤ 0.27. The first barrier layer is Al. c1 In d1 Ga (1-c1-d1) N layers, the second barrier layer is Al c2 In d2 Ga (1-c2-d2) N layers, where 0≤c1≤1, 0≤d1≤1, 0≤c2≤1, 0≤d2≤1. The material selection of the potential well layer and the barrier layer can, on the one hand, ensure that the active layer 12 can radiate the desired wavelength; on the other hand, the difference in In content between the first potential well layer 1211 and the second potential well layer 1221 can effectively suppress the polarization electric field and facilitate the change of compressive stress in the active layer 12, thereby alleviating the compressive stress in the active layer 12, which is beneficial to improving the half-width characteristic of the wavelength and suppressing the blue shift of the wavelength.

[0106] In a further optional embodiment, the same reference is made. Figure 8 The band gap of the first potential well layer 121 is larger than that of the second potential well layer 122. The band gap settings of the first potential well layer 1211 and the second potential well layer 1221 can block hole injection into non-light-emitting regions other than the second sequence 122, which serves as the main light-emitting region, thereby improving the internal quantum efficiency of the light-emitting diode and increasing its brightness.

[0107] In addition to the optional embodiments identical to Embodiment 1, the material composition of each layer in the first sequence 121 and the second sequence 122 in this embodiment can also be: the first well layer 2111 and the second well layer 1221 are both InGaN layers, wherein the In content of the second well layer 1221 is higher than the In content of the first well layer 1211; the first barrier layer 1212 and the second barrier layer 1222 are both AlInGaN layers, wherein the Al content of the second barrier layer 1222 is higher than the Al content of the first barrier layer 1212.

[0108] In an optional embodiment, the thickness of the first sequence 121 is less than or equal to the thickness of the second sequence 122. By making the second sequence 122, which serves as the main light-emitting region, thicker, the luminous efficiency of the light-emitting diode can be maintained while improving display performance. The thickness limitation of the first sequence 121 ensures that it can significantly suppress the polarization electric field and stress of the active layer 12, which helps to improve the half-width characteristic of the wavelength and reduce blue shift. The thickness limitation of the second sequence 122 ensures the light radiation of the active layer.

[0109] Example 3

[0110] See Figure 9 This embodiment provides a light-emitting device 200, including a circuit board 201 and a plurality of light-emitting sources 202 arranged in an array on the circuit board 201. A driving circuit is provided in the circuit board 201, and the light-emitting sources 202 are electrically connected to the driving circuit so that they can be controlled by the driving circuit to light up or turn off. The light-emitting sources 202 include the light-emitting diodes provided in Embodiment 2. The light-emitting device 200 can be an automotive lamp, such as a brake light, turn signal, or ambient light, or it can be other lighting devices, such as a projector, stage light, or display screen. The light-emitting device 200 provided in this embodiment has a good and stable light-emitting effect.

[0111] In summary, the epitaxial structure, light-emitting diode, and light-emitting device provided in this application effectively overcome the various shortcomings of the prior art and have high industrial application value.

[0112] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A light-emitting diode, characterized in that, The light-emitting diode includes at least one epitaxial structure, which comprises at least a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially; wherein... The active layer includes multiple periodic quantum well structures. In the direction from the first semiconductor layer to the second semiconductor layer, the active layer includes a first sequence and a second sequence formed above the first sequence. The first sequence includes a periodically stacked first potential well layer and a first potential barrier layer, and the second sequence includes a periodically stacked second potential well layer and a second potential barrier layer. The first potential well layer and the second potential well layer are In-containing nitride material layers. The first potential well layer and the first barrier layer have a first In content difference, and the second potential well layer and the second barrier layer have a second In content difference, and the second In content difference is greater than the first In content difference.

2. The light-emitting diode according to claim 1, characterized in that, The first sequence comprises a first potential well layer and a first potential barrier layer with x cycles, and the second sequence comprises a second potential well layer and a second potential barrier layer with y cycles, where x and y are both integers greater than or equal to 1, and y ≥ x.

3. The light-emitting diode according to claim 2, characterized in that, In the first sequence, 1 ≤ x ≤ 15, and in the second sequence, 1 ≤ y ≤ 20.

4. The light-emitting diode according to claim 1, characterized in that, The first potential well layer is Al a1 In b1 Ga (1-a1-b1) N layers, the second potential well layer is Al a2 In b2 Ga (1-a2-b2) There are N layers, where 0 < a1, a2 < 0.05, 0 < b1 < 0.3, 0 < b2 ≤ 0.3, and b1 < b2.

5. The light-emitting diode according to claim 1, characterized in that, The first potential well layer is Al a1 In b1 Ga (1-a1-b1) N, where the second potential well layer is Al a2 In b2 Ga (1- a2-b2) There are N layers, where 0 < a1, a2 ≤ 0.02, 0 < b1 ≤ 0.27, 0 < b2 ≤ 0.3, and b1 < b2.

6. The light-emitting diode according to claim 1, characterized in that, The first barrier layer is Al c1 In d1 Ga (1-c1-d1) N layers, the second barrier layer is Al c2 In d2 Ga (1-c2-d2) N layers, where 0≤c1≤1, 0≤d1≤1, 0≤c2≤1, 0≤d2≤1.

7. The light-emitting diode according to claim 1, characterized in that, The first potential well layer and the second potential well layer are made of the same material.

8. The light-emitting diode according to claim 1, characterized in that, The first barrier layer and the second barrier layer are made of the same material.

9. The light-emitting diode according to claim 1, characterized in that, The thickness of the first sequence is less than or equal to the thickness of the second sequence.

10. The light-emitting diode according to claim 9, characterized in that, The thickness of the first sequence is between 100 Å and 3000 Å, and the thickness of the second sequence is between 100 Å and 4000 Å.

11. The light-emitting diode according to claim 1, characterized in that, The band gap of the first potential well layer is larger than that of the second potential well layer.

12. A light-emitting diode, characterized in that, The light-emitting diode includes at least one epitaxial structure, which comprises at least a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially; wherein... The active layer includes multiple periodic quantum well structures. In the direction from the first semiconductor layer to the second semiconductor layer, the active layer includes a first sequence and a second sequence formed above the first sequence. The first sequence includes a periodically stacked first potential well layer and a first potential barrier layer, and the second sequence includes a periodically stacked second potential well layer and a second potential barrier layer. The first potential well layer and the first potential barrier layer have a first bandgap difference, the second potential well layer and the second potential barrier layer have a second bandgap difference, and the second bandgap difference is greater than the first bandgap difference.

13. The light-emitting diode according to claim 12, characterized in that, The first sequence comprises a first potential well layer and a first potential barrier layer with x cycles, and the second sequence comprises a second potential well layer and a second potential barrier layer with y cycles, where x and y are both integers greater than or equal to 1, and y ≥ x.

14. The light-emitting diode according to claim 12, characterized in that, The first potential well layer is Al a1 In b1 Ga (1-a1-b1) N layers, the second potential well layer is Al a2 In b2 Ga (1-a2-b2) There are N layers, where 0 < a1, a2 < 0.05, 0 < b1 < 0.3, 0 < b2 ≤ 0.3, and b1 < b2.

15. The light-emitting diode according to claim 12, characterized in that, The first barrier layer is Al c1 In d1 Ga (1-c1-d1) N layers, the second barrier layer is Al c2 In d2 Ga (1-c2-d2) N layers, where 0≤c1≤1, 0≤d1≤1, 0≤c2≤1, 0≤d2≤1.

16. The light-emitting diode according to claim 12, characterized in that, The thickness of the first sequence is less than or equal to the thickness of the second sequence.

17. The light-emitting diode according to claim 12, characterized in that, The band gap of the first potential well layer is larger than that of the second potential well layer.

18. A light-emitting device, characterized in that, It includes a light source, wherein the light source is a light-emitting diode as described in any one of claims 1 to 17.

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