Light emitting diode and light emitting device

Abstract

The application belongs to the technical field of semiconductor manufacturing, and provides a light emitting diode and a light emitting device. The light emitting diode comprises an epitaxial structure, the epitaxial structure comprises a first semiconductor layer, a transition layer, an active layer and a second semiconductor layer which are sequentially stacked; the transition layer comprises a first superlattice layer and a second superlattice layer which are sequentially stacked, the first superlattice layer comprises a first potential well layer and a first potential barrier layer which are periodically stacked, and the second superlattice layer comprises a second potential well layer and a second potential barrier layer which are periodically stacked; wherein the well-barrier potential difference of the first superlattice layer is greater than the well-barrier potential difference of the second superlattice layer, the carrier in the active layer can be constrained, the carrier overflow can be reduced, the radiation recombination light emitting efficiency of the active layer can be ensured, the device has good stress modulation capacity, the restriction on the carrier can be reduced, the excessive localization of the superlattice region can be reduced, the carrier distribution uniformity can be improved, and the light emitting brightness of the device is enhanced.

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] A light-emitting diode (LED) is a semiconductor solid-state light-emitting device that uses a semiconductor PN junction as the light-emitting material to directly convert electrical energy into light energy. Gallium nitride (GaN) is a group III nitride material with a wide bandgap, possessing excellent properties such as high electron drift saturation velocity, good thermal conductivity, strong chemical bonds, and high temperature resistance. At room temperature, its emission wavelength covers the near-infrared, visible, and near-ultraviolet bands, making it widely used in the LED field.

[0003] Because GaN is a polar material, when an electric field is applied, its conduction and valence bands tilt. This tilt leads to spatial separation of the wave functions of holes and electrons, reducing electron-hole recombination and thus lowering the exciton binding energy, resulting in a decrease in luminescence intensity. This phenomenon is known as the quantum confinement Stark effect (QCSE). To mitigate QCSE, superlattice structures of varying logarithmic values ​​are typically introduced before the luminescent quantum well to release stress. However, the introduction of superlattice structures increases the thickness of the indium (In) composition grown at low temperatures. Furthermore, the superlattice enhances the localization effect of electrons, leading to uneven electron distribution within the luminescent quantum well. This is particularly problematic for green LEDs, where the large well-barrier potential difference creates strongly localized states for electrons, reducing luminescence brightness. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a light-emitting diode and a light-emitting device that can improve quantum efficiency and improve radiative recombination luminescence efficiency.

[0005] To achieve the above and other related objectives, in a first aspect, this application provides a light-emitting diode, including an epitaxial structure, wherein the epitaxial structure includes a first semiconductor layer, a transition layer, an active layer and a second semiconductor layer stacked sequentially; The transition layer includes a first superlattice layer and a second superlattice layer stacked together. The first superlattice layer is located on the side of the second superlattice layer close to the active layer. The first superlattice layer includes a first potential well layer and a first potential barrier layer stacked periodically. The second superlattice layer includes a second potential well layer and a second potential barrier layer stacked periodically. The well-barrier potential difference of the first superlattice layer is greater than that of the second superlattice layer.

[0006] Secondly, this application also provides another light-emitting diode, including an epitaxial structure, the epitaxial structure including a first semiconductor layer, a transition layer, an active layer and a second semiconductor layer stacked sequentially; The transition layer includes a first superlattice layer and a second superlattice layer stacked together. The first superlattice layer is located on the side of the second superlattice layer close to the active layer. The first superlattice layer includes a first potential well layer and a first potential barrier layer stacked periodically. The second superlattice layer includes a second potential well layer and a second potential barrier layer stacked periodically. Both the first superlattice layer and the second superlattice layer contain an In component. The In component has a concentration curve along the thickness direction of the epitaxial structure. In the concentration curve, the In concentration of the first superlattice layer has several first peaks and several first valleys, and the In concentration of the second superlattice layer has several second peaks and several second valleys. At least one of the In concentration differences between the first peak and the adjacent first valley is greater than the In concentration difference between the second peak and the adjacent second valley.

[0007] Thirdly, this application also provides a light-emitting device, including at least one light source, the light source including any of the light-emitting diodes in the foregoing embodiments.

[0008] As described above, compared with the prior art, the light-emitting diode and light-emitting device provided in this application have at least the following beneficial technical effects: In a light-emitting diode (LED), the first superlattice layer near the active layer has a larger well-barrier potential difference, which can effectively confine the carriers in the active layer, reduce carrier overflow, and improve the QCSE effect of the active layer. The second superlattice layer away from the active layer has a smaller well-barrier potential difference, which can reduce the confinement of carriers, improve carrier mobility and distribution uniformity, and reduce the localization of electrons in the superlattice region. By combining the first superlattice layer with a larger well-barrier potential difference with the second superlattice layer with a smaller well-barrier potential difference, the radiative recombination luminescence efficiency of the active layer can be improved, while also taking into account good stress modulation capability, thereby improving the luminous brightness of the final product. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 The diagram shown is a schematic diagram of the structure of a light-emitting diode provided in Embodiment 1 of this application.

[0011] Figure 2 The diagram shows the structure of the first superlattice layer and the second superlattice layer in the light-emitting diode provided in this application.

[0012] Figure 3 The diagram shown is a schematic diagram of the structure of a light-emitting diode with a stress buffer layer provided in this application.

[0013] Figure 4 The diagram shown is a schematic diagram of the structure of a light-emitting diode with a substrate and a buffer layer provided in this application.

[0014] Figure 5 The diagram shown is a schematic diagram of the concentration curves of each component in the light-emitting diode provided in Embodiment 2 of this application along the thickness direction of the epitaxial structure.

[0015] Explanation of reference numerals in the attached figures: 10. Substrate; 20. Epitaxial structure; 21. First semiconductor layer; 22. Transition layer; 221. First superlattice layer; 2211. First potential well layer; 2212. First potential barrier layer; 222. Second superlattice layer; 2221. Second potential well layer; 2222. Second potential barrier layer; 223. Stress relief layer; 23. Active layer; 24. Second semiconductor layer; 25. Electron blocking layer; 30. Buffer layer. Detailed Implementation

[0016] To make the technical objectives, technical solutions, and technical effects of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0018] In the description of this application, it should be noted that the terms "one embodiment," "some embodiments," "optional embodiments," and "example," etc., refer to specific features, structures, materials, or characteristics described in conjunction with implementation methods or examples, which are included in at least one implementation method or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same implementation method or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more implementation methods or examples.

[0019] To address the technical problems existing in the background art, in a first aspect, the present invention provides a light-emitting diode, the light-emitting diode comprising an epitaxial structure, the epitaxial structure comprising a first semiconductor layer, a transition layer, an active layer and a second semiconductor layer stacked sequentially; The transition layer includes a first superlattice layer and a second superlattice layer stacked together. The first superlattice layer is located on the side of the second superlattice layer close to the active layer. The first superlattice layer includes a first potential well layer and a first potential barrier layer stacked periodically. The second superlattice layer includes a second potential well layer and a second potential barrier layer stacked periodically. The well-barrier potential difference of the first superlattice layer is greater than that of the second superlattice layer.

[0020] By giving the first superlattice layer near the active layer a larger well-barrier potential difference, the carriers in the active layer can be effectively confined under stress release conditions, reducing carrier overflow, improving the QCSE effect of the active layer, and ensuring the radiative recombination luminescence efficiency of the active layer. By giving the second superlattice layer away from the active layer a smaller well-barrier potential difference, the confinement effect on carriers can be reduced, promoting lateral expansion and vertical migration of carriers, reducing excessive localization of electrons in the superlattice region, improving the uniformity of carrier distribution, and thus improving the luminescence brightness of the device.

[0021] In some embodiments, the first potential well layer is In a1 Ga (1-a1) N layers, the first barrier layer is Al b1 Ga (1-b1) For N layers, 0.15≤a1≤0.25, 0≤b1≤0.1.

[0022] By limiting the material and component content of the first potential well layer and the first potential barrier layer, a large potential difference between the first potential well layer and the first potential barrier layer can be ensured, thereby promoting stress release during the growth process and achieving the suppression effect of QCSE phenomenon in the active layer.

[0023] In some embodiments, the second potential well layer and the second potential barrier layer are made of the same material, and both are In-containing nitride material layers, wherein the In component content in the second potential well layer is greater than the In component content in the second potential barrier layer.

[0024] In some embodiments, the In concentration in the second barrier layer is 30% to 70% of the In concentration in the second well layer.

[0025] In some embodiments, the second potential well layer is In c1 Ga (1-c1) N layers, the second barrier layer is Ald1 In d2 Ga (1-d1-d2) N layers, where 0≤d1≤0.03, 0.01≤d2≤0.1, and 0.15≤c1≤0.25.

[0026] In some embodiments, the second barrier layer is In d2 Ga (1-d2) N layers, where 0.02≤d2≤0.1.

[0027] In some embodiments, the In concentration in the second potential well layer is 1.2E20cm³. -3 ~2E20cm -3 The In concentration in the second barrier layer is 5E19cm⁻¹ -3 ~1E20cm -3 .

[0028] In some embodiments, the In / Ga ratio in the second barrier layer is 5% to 50% of the In / Ga ratio in the second well layer.

[0029] By controlling the composition of the second well layer and the second barrier layer, as well as the In content, a certain potential difference between the two layers can be ensured, resulting in certain defects at the interface. This further promotes stress release during the growth process. At the same time, a relatively small potential difference between the two layers is maintained, avoiding excessive defects at the interface that could affect the growth quality of subsequent material layers and reduce the improvement effect on electron injection efficiency and distribution uniformity.

[0030] In some embodiments, the first superlattice layer includes a first potential well layer and a first potential barrier layer with x periods, and the second superlattice layer includes a second potential well layer and a second potential barrier layer with y periods, wherein 1≤x≤3, 1<y≤8, and y>x.

[0031] In some embodiments, the thickness of the second potential well layer is 5 Å to 25 Å, and the thickness of the second potential barrier layer is 50 Å to 100 Å.

[0032] By controlling the number of cycles in the first and second superlattice layers, as well as the thickness of their well and barrier layers, the first superlattice layer with a larger well-barrier potential difference can form an effective barrier to confine carriers in the active layer, prevent carrier overflow, and ensure stress release during growth. At the same time, it prevents the first superlattice layer from becoming too large and increasing localization, which would lead to a deterioration in electron injection. Furthermore, it ensures that the second superlattice layer with a larger number of cycles can improve the uniformity of electron injection, further promote stress release during growth, and improve luminescence.

[0033] In some embodiments, the transition layer further includes a stress relief layer located between the second superlattice layer and the first semiconductor layer. By providing a stress relief layer, the lattice mismatch stress during the growth process can be initially released, reducing the transmission of stress to subsequent superlattice layers and active layers, and avoiding epitaxial layer cracking or increased defects caused by stress accumulation.

[0034] In a second aspect, the present invention also provides another light-emitting diode, the light-emitting diode comprising an epitaxial structure, the epitaxial structure comprising a first semiconductor layer, a transition layer, an active layer and a second semiconductor layer stacked sequentially. The transition layer includes a first superlattice layer and a second superlattice layer stacked together. The first superlattice layer is located on the side of the second superlattice layer close to the active layer. The first superlattice layer includes a first potential well layer and a first potential barrier layer stacked periodically. The second superlattice layer includes a second potential well layer and a second potential barrier layer stacked periodically. Both the first superlattice layer and the second superlattice layer contain an In component. The In component has a concentration curve along the thickness direction of the epitaxial structure. In the concentration curve, the In concentration of the first superlattice layer has several first peaks and several first valleys, and the In concentration of the second superlattice layer has several second peaks and several second valleys. At least one of the In concentration differences between the first peak and the adjacent first valley is greater than the In concentration difference between the second peak and the adjacent second valley.

[0035] In the first and second superlattice layers, the concentration fluctuation of the In component along the thickness direction of the epitaxial structure causes the In component concentration to form several first peaks and first valleys, as well as several second peaks and second valleys in the concentration curve. Furthermore, the concentration distribution of the In component affects the well-barrier potential difference between the first and second superlattice layers. By controlling the In concentration difference between at least one first peak and an adjacent first valley to be greater than the In concentration difference between a second peak and an adjacent second valley, the first superlattice layer closer to the active layer has a relatively large well-barrier potential difference. This effectively confines the carriers in the active layer, reducing carrier overflow, while the second superlattice layer closer to the first semiconductor layer has a relatively small well-barrier potential difference. This reduces the confinement effect on carriers, improves the uniformity of carrier distribution, helps promote lateral carrier expansion, and enhances the device's luminous brightness.

[0036] In some embodiments, the first superlattice layer comprises a first potential well layer and a first potential barrier layer with x periods, and the second superlattice layer comprises a second potential well layer and a second potential barrier layer with y periods, where 1≤x≤3, 1<y≤8, and y>x.

[0037] By limiting the number of cycles of well and barrier layers in the first superlattice layer, an effective barrier can be formed in the first superlattice layer with a large well-barrier potential difference. This confines carriers in the active layer, preventing carrier overflow, and also ensures stress release during growth, improving the growth quality of the superlattice and active layer. Furthermore, it prevents excessive cycle number from leading to excessive size and enhanced localization. Similarly, by limiting the number of cycles of well and barrier layers in the second superlattice layer, electron uniform injection can be improved using a smaller well-barrier potential difference. This further promotes stress release during growth and improves the device's luminescence performance.

[0038] In some embodiments, the first potential well layer is In a1 Ga (1-a1) N layers, the first barrier layer is Al b1 Ga (1-b1) For N layers, 0.15≤a1≤0.25, 0≤b1≤0.1.

[0039] In some embodiments, the second potential well layer is In c1 Ga (1-c1) N layers, the second barrier layer is Al d1 In d2 Ga (1-d1-d2) N layers, where 0≤d1≤0.03, 0.01≤d2≤0.1, and 0.15≤c1≤0.25.

[0040] By controlling the materials and In composition of the second well layer and the second barrier layer, on the one hand, it is possible to ensure that there is a certain well-barrier potential difference between the second well layer and the second barrier layer, so that certain defects are formed at the interface, which further promotes stress release during the growth process. On the other hand, it is also possible to avoid the well-barrier potential difference being too large, which would reduce the improvement effect on electron injection efficiency and distribution uniformity, and lead to too many defects at the interface, thus affecting the growth quality of the superlattice and subsequent active layers.

[0041] In some embodiments, the In concentration in the second barrier layer is 30% to 70% of the In concentration in the second well layer.

[0042] Since the second well layer is generally grown at a relatively low temperature and the second barrier layer is generally grown at a relatively high temperature, doping with In reduces the compressive stress of the well and barrier, resulting in a decrease in the probability of electron tunneling. By controlling the In content in the well and barrier layers and coordinating with the size design, the difficulty of electron migration can be avoided, which helps to improve the electron injection efficiency and the uniformity of electron distribution.

[0043] Thirdly, the present invention also provides a light-emitting device, including at least one light source, the light source including any of the light-emitting diodes in the foregoing embodiments.

[0044] To provide a more detailed explanation of the solutions in this application, the following embodiments are provided. It should be noted that the technical features and solutions in the following embodiments can be combined with each other without conflict.

[0045] Example 1 This embodiment provides a light-emitting diode, as shown in the reference. Figure 1 The light-emitting diode includes at least one epitaxial structure 20, which includes a first semiconductor layer 21, a transition layer 22, an active layer 23, and a second semiconductor layer 24 stacked sequentially.

[0046] The first semiconductor layer 21 and the second semiconductor layer 24 have opposite conductivity types. Specifically, for example, the first semiconductor layer 21 can be an n-type semiconductor layer and the second semiconductor layer 24 can be a p-type semiconductor layer, or the first semiconductor layer 21 can be a p-type semiconductor layer and the second semiconductor layer 24 can be an n-type semiconductor layer. Electrons or holes can be provided through n-type doping or p-type doping, respectively. The n-type semiconductor layer can be doped with, for example, Si, Ge, Sn, Se, Te, and other suitable n-type impurities, and the p-type semiconductor layer can be doped with, for example, Mg, Zn, Ca, Sr, C, Ba, or other suitable p-type impurities. In this embodiment, the first semiconductor layer 21 is an n-type semiconductor layer as an example.

[0047] The first semiconductor layer 21, the active layer 23, and the second semiconductor layer 24 can be made of III-V compound semiconductor materials, specifically gallium nitride, aluminum gallium nitride, gallium arsenide, or other suitable materials. The first semiconductor layer 21 and the second semiconductor layer 24 can be single-layer or multi-layer structures. The active layer 23 can be formed by alternating stacked well layers and barrier layers to create a single-layer or multi-layer quantum well structure. Under the influence of current, electrons and holes provided by the first semiconductor layer 21 and the second semiconductor layer 24 recombine in the active layer 23 to generate light of a specific wavelength. By adjusting the content or composition of each component in the active layer 23, the wavelength of the light output by the epitaxial structure 20 can be adjusted.

[0048] The transition layer 22, as a non-light-emitting layer, is disposed between the first semiconductor layer 21 and the active layer 23. On the one hand, it is used to realize stress release during the growth process and improve the growth quality of the thin film. On the other hand, it can also form an effective barrier to confine the carriers in the active layer 23 and prevent carrier overflow from causing a decrease in luminous efficiency.

[0049] Reference Figure 2The transition layer 22 includes a first superlattice layer 221 and a second superlattice layer 222 stacked together. The first superlattice layer 221 is located on the side of the second superlattice layer 222 close to the active layer 23. The first superlattice layer 221 includes a first potential well layer 2211 and a first potential barrier layer 2212 stacked periodically. The second superlattice layer 222 includes a second potential well layer 2221 and a second potential barrier layer 2222 stacked periodically. The potential difference between the well and the barrier in the band structure of the first superlattice layer 221 is greater than the potential difference between the well and the barrier in the band structure of the second superlattice layer 222.

[0050] By giving the first superlattice layer 221 a large well-barrier potential difference, an effective barrier can be formed to confine the carriers in the active layer 23, reduce overflow, improve the QCSE effect of the active layer 23, and ensure the radiative recombination luminescence efficiency of the active layer 23. On the other hand, it can also achieve good stress release and improve growth quality. By giving the second superlattice layer 222 a small well-barrier potential difference, the confinement effect on the carriers can be reduced, promoting the lateral expansion and vertical migration of the carriers, reducing the excessive localization of the superlattice region. Together with the first superlattice layer 221, the uniformity of carrier distribution is effectively improved, and the luminous brightness of the device is increased.

[0051] In this embodiment, the potential difference refers to the energy difference between the energy bands of the two material layers in the light-emitting diode, used to characterize the size of the barrier height. Furthermore, it should be noted that the active layer 23 should avoid using two different potential differences to prevent different wavelength shifts when the current changes, which could lead to incompatibility with different current requirements and uneven carrier distribution, resulting in severe efficiency loss and color inconsistency.

[0052] In this embodiment, the first potential well layer 2211 and the first potential barrier layer 2212 are each formed of a combination of one or more materials with a relatively large potential difference between the well and the barrier. Optionally, the first potential well layer 2211 is, for example, In. a1 Ga (1-a1) For layer N, 0.04 ≤ a1 ≤ 0.25. The specific value of a1 can be set according to actual needs. For example, when the emission wavelength of the active layer is in the green light band, the value of a1 can be 0.15~0.25; when the emission wavelength of the active layer 23 is in the blue light band, the value of a1 can be 0.04~0.15. The first barrier layer 2212 is, for example, Al. b1 Ga (1-b1) For N layers, 0 ≤ b1 ≤ 0.1. Specifically, a1 and b1 can be, for example, 0.15 and 0, or 0.18 and 0.04, or 0.22 and 0.08, or 0.25 or 0.1, or other suitable values.

[0053] By limiting the composition of the first well layer 2211 and the first barrier layer 2212 and the content of each component, a large well-barrier potential difference can be formed between the first well layer 2211 and the first barrier layer 2212, thereby improving the stress release effect during the growth process and suppressing the QCSE phenomenon.

[0054] In this embodiment, the second potential well layer 2221 and the second potential barrier layer 2222 are respectively formed by a combination of one or more materials with relatively small potential difference between the well and the barrier. Specifically, for example, the second potential well layer 2221 and the second potential barrier layer 2222 can be made of the same material with different component contents, or the second potential well layer 2221 and the second potential barrier layer 2222 can also be formed by a combination of two or more different materials.

[0055] In some embodiments, the second potential well layer 2221 and the second potential barrier layer 2222 are made of the same material, and both are In-containing nitride material layers. The In content of the second potential well layer 2221 is greater than the In content of the second potential barrier layer 2222, which enables the second potential well layer 2221 and the second potential barrier layer 2222 to have a potential difference between them, so that the second superlattice layer 222 can achieve stress relief.

[0056] In some embodiments, the second potential well layer 2221 is In c1 Ga (1-c1) For layer N, 0.04 ≤ c1 ≤ 0.25, where c1 can be, for example, 0.15, 0.18, 0.22, 0.25, or other suitable values. The specific value range can be set according to design requirements. Specifically, when the emission wavelength of the active layer 23 is in the green light band, for example, 495nm~570nm, the value of c1 can be 0.15~0.25; when the emission wavelength of the active layer 23 is in the blue light band, for example, 400nm~495nm, the value of c1 can be 0.04~0.15. The second barrier layer 2222 is Al. d1 In d2 Ga (1-d1-d2) N layers, where 0≤d1≤0.03, d1 can be, for example, 0, 0.01, 0.02, 0.03 or other suitable values, 0.01≤d2≤0.1, d2 can be, for example, 0.01, 0.04, 0.06, 0.08, 0.1 or other suitable values.

[0057] By controlling the material composition and content of each component in the second potential well layer 2221 and the second barrier layer 2222, a certain potential difference between the two layers is ensured. This allows the second superlattice layer 222 to have a certain ability to block charge carriers and creates certain defects at the interface, further promoting stress release during growth. Furthermore, by making this potential difference relatively small, compared to traditional superlattice structures, the confinement of electrons is reduced, which helps improve electron injection efficiency and distribution uniformity. Simultaneously, excessive defects at the interface are prevented from affecting the growth quality of subsequent material layers, effectively improving the luminous efficiency of the final product. In addition, since the transition layer 22 is not a light-emitting layer, controlling the In content also prevents excessive In concentration from affecting growth quality and the luminous brightness of the active layer 23.

[0058] Furthermore, the second barrier layer 2222 is In d2 Ga (1-d2) N layers, where 0.02≤d2≤0.1.

[0059] In this embodiment, the first superlattice layer 221 includes a first potential well layer 2211 and a first barrier layer 2212 with x periods, and the second superlattice layer 222 includes a second potential well layer 2221 and a second barrier layer 2222 with y periods, wherein 1≤x≤3 to prevent the electron injection effect from deteriorating due to an excessive number of periods in the first superlattice layer 221, and 1<y≤8. Specifically, x and y can be, for example, 1 and 2, or 1 and 4, or 2 and 6, or 3 and 8, which can be set according to actual needs.

[0060] Preferably, x and y also satisfy the following relationship: x / (x+y)≤1 / 3.

[0061] In an optional embodiment, the thickness of the second potential well layer 2221 is 5 Å to 25 Å, specifically, for example, 5 Å, 10 Å, 15 Å, 20 Å, 25 Å or other suitable dimensions, and the thickness of the second potential barrier layer 2222 is 50 Å to 100 Å, specifically, for example, 50 Å, 70 Å, 90 Å, 100 Å or other suitable dimensions.

[0062] By controlling the number of cycles of the first superlattice layer 221 and the second superlattice layer 222, as well as the thickness of their well and barrier layers, the first superlattice layer 221, with its large well-barrier potential difference, can form an effective barrier to confine the carriers in the active layer 23, prevent carrier overflow, and ensure stress release during growth. At the same time, it prevents the size from becoming too large and thus increasing localization. Furthermore, it ensures that the second superlattice layer 222, with its smaller well-barrier potential difference, can achieve improved uniform electron injection and promote stress release during growth.

[0063] In an optional embodiment, during the growth of the second superlattice layer 222, the growth temperature of the second potential well layer 2221 is lower than the growth temperature of the second barrier layer 2222. Further, the growth temperature of the second potential well layer 2221 is 700°C to 830°C, specifically, for example, 730°C, 750°C, 780°C, 800°C, 830°C, or other suitable temperatures; the growth temperature of the second barrier layer 2222 is 760°C to 880°C, specifically, for example, 760°C, 780°C, 830°C, 850°C, 880°C, or other suitable temperatures.

[0064] A low-temperature growth atmosphere helps suppress indium atom volatilization and reduce indium atom desorption, while a high-temperature growth atmosphere helps improve growth quality. By controlling the growth temperature and thickness of the second well layer 2221 and the second barrier layer 2222, the growth quality of the superlattice region can be improved while maintaining stress release during growth, ensuring the improvement effect on electron injection efficiency and electron distribution uniformity. In addition, since the growth temperature of the second barrier layer 2222 is relatively high, the compressive stress of the well will be reduced when In is doped, resulting in a decrease in the electron tunneling probability. By further limiting the In composition content of the second barrier layer 2222, combined with limiting the thickness of the second well layer 2221 and the second barrier layer 2222, the difficulty of electron migration can be avoided, preventing a reduction in the improvement effect on electron injection efficiency and distribution uniformity. Furthermore, it can also prevent excessive differences in In composition at the interface from leading to an increase in defects that would affect the growth quality of the superlattice and the subsequent active layer 23.

[0065] In this embodiment, refer to Figure 3 The transition layer 22 also includes a stress relief layer 223, which is located between the second superlattice layer 222 and the first semiconductor layer 21. The stress relief layer 223 is used to release the lattice mismatch stress between the first semiconductor layer 21 and the second superlattice layer 222, reduce the stress transmission to subsequent superlattice layers and active layers, and avoid epitaxial layer cracking or increased defects caused by stress accumulation.

[0066] In some embodiments, the stress relief layer 223 is a multilayer structure formed by sequentially stacking or alternatingly stacking one or more materials such as GaN, InGaN, and AlGaN. Specifically, the stress relief layer 223 can be, for example, a superlattice structure. There is a large potential difference between adjacent material layers in the stress relief layer 223 to facilitate stress release.

[0067] Reference Figure 4 The epitaxial structure 20 may also include an electron blocking layer 25, which is located between the active layer 23 and the second semiconductor layer 24. The electron blocking layer 25 is used to block the overflow of charge carriers to the second semiconductor layer 24, increase the recombination probability of electrons and holes in the active layer 23, and improve the luminous efficiency. The electron blocking layer 25 may be an AlGaN layer or other suitable material layer.

[0068] Similarly, refer to Figure 4 The light-emitting diode in this embodiment may further include a substrate 10 and an electrode structure. The electrode structure includes a first electrode and a second electrode. The first electrode is electrically connected to the first semiconductor layer 21, and the second electrode is electrically connected to the second semiconductor layer 24. The substrate 10 may be a growth substrate suitable for growing the epitaxial structure 20, such as a sapphire substrate or a silicon carbide substrate. Optionally, a buffer layer 30 may be formed between the substrate 10 and the epitaxial structure 20 to reduce defects such as dislocations between the substrate 10 and the epitaxial structure 20 and improve the crystal growth quality. The buffer layer 30 may, for example, include a first buffer layer, a nucleation layer, and a leveling layer stacked sequentially.

[0069] Example 2 This embodiment provides another light-emitting diode, which also includes an epitaxial structure 20 that radiates light of a certain wavelength under the influence of current. The similarities to Embodiment 1 will not be repeated here; the differences are as follows.

[0070] The epitaxial structure 20 includes a first semiconductor layer 21, a transition layer 22, an active layer 23, and a second semiconductor layer 24 stacked sequentially. The transition layer 22 includes a first superlattice layer 221 and a second superlattice layer 222 stacked together. The first superlattice layer 221 is located on the side of the second superlattice layer 222 close to the active layer 23. The first superlattice layer 221 includes a first potential well layer 2211 and a first potential barrier layer 2212 stacked periodically. The second superlattice layer 222 includes a second potential well layer 2221 and a second potential barrier layer 2222 stacked periodically.

[0071] Figure 5 The concentration curves of Ga and In in a light-emitting diode along the thickness direction of the epitaxial structure 20 are shown. The first superlattice layer 221 and the second superlattice layer 222 both contain In components. The In components have a concentration curve along the thickness direction of the epitaxial structure 20. In the concentration curve, the In concentration of the first superlattice layer 221 has several first peaks and several first valleys, and the In concentration of the second superlattice layer 222 has several second peaks and several second valleys. The In concentration difference between at least one first peak and an adjacent first valley is greater than the In concentration difference between a second peak and an adjacent second valley.

[0072] In this embodiment, the active layer 23 should avoid using two different In concentration differences as much as possible to prevent the active layer 23 from having two different potential differences, which would lead to uneven carrier distribution.

[0073] In the first superlattice layer 221 and the second superlattice layer 222, the concentration fluctuation of the In component along the thickness direction of the epitaxial structure 20 causes the In component concentration curve to form several first peaks and first valleys, as well as several second peaks and second valleys. The concentration distribution of the In component affects the well-barrier potential difference of the first superlattice layer 221 and the second superlattice layer 222. In this embodiment, by controlling the In concentration difference between at least one first peak and an adjacent first valley to be greater than the In concentration difference between a second peak and an adjacent second valley, the first superlattice layer 221 near the active layer 23 has a relatively large well-barrier potential difference, thereby effectively confining the carriers in the active layer 23, reducing carrier overflow, and the second superlattice layer 222 near the first semiconductor layer 21 has a relatively small well-barrier potential difference, so as to reduce the confinement effect on the carriers, improve the carrier injection efficiency and distribution uniformity, and enhance the device luminous brightness.

[0074] In this embodiment, the first potential well layer 2211 is In a1 Ga (1-a1) N layers, the first barrier layer 2212 is Al b1 Ga (1-b1) N layers, where 0.15≤a1≤0.25, 0≤b1≤0.1. The second potential well layer 2221 is In. c1 Ga (1-c1) N layers, 0.04≤c1≤0.25, the second barrier layer 2222 is Al d1 In d2 Ga (1-d1-d2) For N layers, 0 ≤ d1 ≤ 0.03, 0.01 ≤ d2 ≤ 0.1.

[0075] In some embodiments, the In concentration in the second barrier layer 2222 is 30% to 70% of the In concentration in the second well layer 2221, and the concentration ratio can be, for example, 30%, 40%, 60%, 70% or other suitable ratios. Preferably, the In concentration in the second barrier layer 2222 is 50% to 70% of the In concentration in the second well layer 2221.

[0076] In some embodiments, the In concentration in the second potential well layer 2221 is 1.2E20cm³. -3 ~2E20cm -3 For example, 1.2E20cm -3 1.5E20cm -3 1.8E20cm -3 2E20cm -3 Or at other suitable concentrations, the In concentration in the second barrier layer 2222 is 5E19cm⁻¹. -3 ~1E20 / cm -3 For example, 5E19cm-3 6E19cm -3 8E19cm -3 10E19cm -3 Or other suitable concentrations.

[0077] In some embodiments, the In / Ga ratio in the second barrier layer 2222 is 5% to 50% of the In / Ga ratio in the second well layer 2221. Specifically, the In / Ga ratio can be, for example, 5%, 15%, 25%, 40%, 50%, or other suitable values. Since the growth temperature of the second barrier layer 2222 is relatively high, In doping reduces the compressive stress of the well, leading to a decrease in the electron tunneling probability. By further limiting the In content or concentration in the second barrier layer 2222, the final In concentration in the second barrier layer 2222 can be 30% to approximately 70% of the In concentration in the second well layer 2221, avoiding an increase in the difficulty of electron migration.

[0078] In this embodiment, by controlling the content and concentration of In components in the second potential well layer 2221 and the second potential barrier layer 2222, it is possible to ensure a certain potential difference between the second potential well layer 2221 and the second potential barrier layer 2222, thereby creating a certain concentration of defects at the interface and promoting stress release. Simultaneously, the second superlattice layer 222 has a certain blocking ability for charge carriers, and this potential difference is relatively small. Compared to traditional superlattice structures, this reduces the confinement of electrons, improves electron injection efficiency and distribution uniformity, and increases luminous efficiency. Furthermore, since the transition layer 22 is not a light-emitting layer, by controlling the maximum content and concentration of In components to be less than the In component content in the active layer 23 (e.g., ...), ... Figure 5 As shown in the figure, it can also prevent the In concentration in the trap layer from being too high, which would affect the growth quality and the luminescence brightness of the active layer 23.

[0079] To further illustrate the effects of the light-emitting diodes provided in Embodiment 1 and Embodiment 2, a pair of examples is provided. The epitaxial structure of the light-emitting diode in the comparative example is basically the same as that in Embodiment 1 or Embodiment 2. The difference is that in the comparative example, the transition layer of the epitaxial structure of the light-emitting diode includes a stress relief layer and a first superlattice layer stacked sequentially, but does not contain a second superlattice layer.

[0080] Tests conducted on the LEDs provided in Embodiment 1, Embodiment 2, and the comparative example revealed that the LEDs provided in Embodiment 1 or Embodiment 2 had a brightness of approximately 2.297 mW and a yield rate of approximately 97.6%, while the LEDs in the comparative example had a brightness of approximately 2.260 mW and a yield rate of approximately 97.0%. It is evident that, compared to traditional LEDs, the LEDs provided in Embodiment 1 and Embodiment 2 show effective improvements in both brightness and yield rate.

[0081] Example 3 This embodiment provides a light-emitting device, including at least one light source, which includes any one of the light-emitting diodes in Embodiment 1 or Embodiment 2, and therefore also has the above-mentioned beneficial effects.

[0082] 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, alter, or combine 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 an epitaxial structure, which includes a first semiconductor layer, a transition layer, an active layer, and a second semiconductor layer stacked sequentially. The transition layer includes a first superlattice layer and a second superlattice layer stacked together. The first superlattice layer is located on the side of the second superlattice layer close to the active layer. The first superlattice layer includes a first potential well layer and a first potential barrier layer stacked periodically. The second superlattice layer includes a second potential well layer and a second potential barrier layer stacked periodically. The well-barrier potential difference of the first superlattice layer is greater than that of the second superlattice layer.

2. The light-emitting diode according to claim 1, characterized in that, The first potential well layer is In a1 Ga (1-a1) N layers, the first barrier layer is Al b1 Ga (1-b1) For N layers, 0.15≤a1≤0.25, 0≤b1≤0.

1.

3. The light-emitting diode according to claim 1, characterized in that, The second potential well layer and the second potential barrier layer are made of the same material, and both are In-containing nitride material layers, wherein the In component content of the second potential well layer is greater than the In component content of the second potential barrier layer.

4. The light-emitting diode according to claim 3, characterized in that, The In concentration in the second barrier layer is 30% to 70% of the In concentration in the second well layer.

5. The light-emitting diode according to claim 1, characterized in that, The second potential well layer is In c1 Ga (1-c1) N layers, the second barrier layer is Al d1 In d2 Ga (1-d1-d2) N layers, where 0≤d1≤0.03, 0.01≤d2≤0.1, and 0.15≤c1≤0.

25.

6. The light-emitting diode according to claim 5, characterized in that, The second barrier layer is In d2 Ga (1-d2) N layers, where 0.02≤d2≤0.

1.

7. The light-emitting diode according to claim 6, characterized in that, The In concentration in the second potential well layer is 1.2E20cm³. -3 ~2E20cm -3 The In concentration in the second barrier layer is 5E19cm⁻¹ -3 ~1E20cm -3 .

8. The light-emitting diode according to claim 5, characterized in that, The In / Ga ratio in the second barrier layer is 5% to 50% of the In / Ga ratio in the second well layer.

9. The light-emitting diode according to claim 1, characterized in that, The first superlattice layer comprises a first potential well layer and a first potential barrier layer with x periods, and the second superlattice layer comprises a second potential well layer and a second potential barrier layer with y periods, wherein 1≤x≤3, 1<y≤8, and y>x.

10. The light-emitting diode according to claim 1, characterized in that, The thickness of the second potential well layer is 5 Å to 25 Å, and the thickness of the second potential barrier layer is 50 Å to 100 Å.

11. The light-emitting diode according to claim 1, characterized in that, The transition layer further includes a stress relief layer located between the second superlattice layer and the first semiconductor layer.

12. A light-emitting diode, characterized in that, The light-emitting diode includes an epitaxial structure, which includes a first semiconductor layer, a transition layer, an active layer, and a second semiconductor layer stacked sequentially. The transition layer includes a first superlattice layer and a second superlattice layer stacked together. The first superlattice layer is located on the side of the second superlattice layer close to the active layer. The first superlattice layer includes a first potential well layer and a first potential barrier layer stacked periodically. The second superlattice layer includes a second potential well layer and a second potential barrier layer stacked periodically. Both the first superlattice layer and the second superlattice layer contain an In component. The In component has a concentration curve along the thickness direction of the epitaxial structure. In the concentration curve, the In concentration of the first superlattice layer has several first peaks and several first valleys, and the In concentration of the second superlattice layer has several second peaks and several second valleys. At least one of the In concentration differences between the first peak and the adjacent first valley is greater than the In concentration difference between the second peak and the adjacent second valley.

13. The light-emitting diode according to claim 12, characterized in that, The first superlattice layer comprises a first potential well layer and a first potential barrier layer with x periods, and the second superlattice layer comprises a second potential well layer and a second potential barrier layer with y periods, wherein 1≤x≤3, 1<y≤8, and y>x.

14. The light-emitting diode according to claim 13, characterized in that, The first potential well layer is In a1 Ga (1-a1) N layers, the first barrier layer is Al b1 Ga (1-b1) For N layers, 0.15≤a1≤0.25, 0≤b1≤0.

1.

15. The light-emitting diode according to claim 13, characterized in that, The second potential well layer is In c1 Ga (1-c1) N layers, the second barrier layer is Al d1 In d2 Ga (1-d1-d2) N layers, where 0≤d1≤0.03, 0.01≤d2≤0.1, and 0.15≤c1≤0.

25.

16. The light-emitting diode according to claim 15, characterized in that, The In concentration in the second barrier layer is 30% to 70% of the In concentration in the second well layer.

17. A light-emitting device, characterized in that, It includes at least one light source, said light source including any one of claims 1 to 16, of which a light-emitting diode is included.

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