A light-emitting diode and a light-emitting device

Abstract

This invention relates to the field of semiconductor manufacturing technology, and particularly to a light-emitting diode (LED) and a light-emitting device. The LED comprises at least an epitaxial stack, including an N-type semiconductor layer, a P-type semiconductor layer, and an active layer located between the N-type and P-type semiconductor layers. The active layer includes a first type of quantum well (QW) layer and a second type of quantum well (QW) layer, with the first type of QW layer being closer to the N-type semiconductor layer than the second type of QW layer. The distance h1 between the first type of QW layer and the N-type semiconductor layer and the distance h2 between the second type of QW layer and the N-type semiconductor layer satisfy: h2 ≥ 2h1. Through this configuration, the luminous intensity ratio of the two types of quantum well layers can be effectively optimized under both high and low current driving conditions. This results in the device's color coordinates being closer to the preset target region in its native luminescent state without phosphor conversion, significantly improving the device's color rendering performance.

Description

[0001] This application is a divisional application of the invention patent application filed on October 23, 2025, with application number 202511516239.9 and invention title "A Light Emitting Diode and Light Emitting Device". Technical Field

[0002] This invention relates to the field of semiconductor manufacturing technology, and in particular to a light-emitting diode and a light-emitting device. Background Technology

[0003] Light-emitting diodes (LEDs) are semiconductor light-emitting elements, typically made of semiconductors such as GaN, GaAs, GaP, and GaAsP. With their significant advantages such as high luminous intensity, high efficiency, small size, and long lifespan, they have been widely used in various fields.

[0004] In the LED field, LED chips fabricated using a monolithic integrated structure of multiple quantum well layers with different luminescent properties have attracted widespread attention due to their ability to simultaneously emit light of multiple wavelengths, thus meeting diverse luminescence requirements. However, in practical applications, such multi-quantum well layer coexistence structures are still affected by the quantum confinement Stark effect (QCSE) and the uneven distribution of charge carriers in different quantum well layers. This leads to an imbalance in the luminescence intensity ratio of each quantum well layer, causing the color coordinates of the device to deviate from the preset target region in its native luminescence state without phosphor conversion, resulting in poor color rendering. Summary of the Invention

[0005] In view of at least one deficiency of the prior art, the purpose of this application is to provide a light-emitting diode that can effectively improve the ratio of luminous intensity of different quantum well layers, so that the color coordinates conform to the target region range, thereby ensuring the color rendering effect of the device.

[0006] In a first aspect, embodiments of this application provide a light-emitting diode (LED), the LED comprising an epitaxial stack, the epitaxial stack comprising an N-type semiconductor layer, a P-type semiconductor layer, and an active layer located between the N-type semiconductor layer and the P-type semiconductor layer; the active layer comprising a first type quantum well layer and a second type quantum well layer, wherein the first type quantum well layer is closer to the N-type semiconductor layer than the second type quantum well layer; the distance h1 between the first type quantum well layer and the N-type semiconductor layer and the distance h2 between the second type quantum well layer and the N-type semiconductor layer satisfy the following: .

[0007] This application also provides a light-emitting device that uses a light-emitting diode as described in the above embodiments.

[0008] The light-emitting diode provided in this application embodiment is configured such that the first type of quantum well layer is positioned closer to the N-type semiconductor layer than the second type of quantum well layer, and the configuration is limited. The distance design allows the first type of quantum well (CQB) layer, located close to the electron source, to capture only a small number of initially injected electrons. Most electrons, due to their higher initial kinetic energy, penetrate the potential barrier and accumulate in the second type of quantum well (CQB) layer, which is further away. Simultaneously, holes, due to their low migration rate, are less likely to diffuse into the CQB layer and instead accumulate more within the CQB layer, leading to increased recombination of holes and electrons within the CQB layer. This differentiated control of carrier distribution significantly widens the spatial gradient between the two CQB layers and the electron source. This allows the structure to effectively reduce the luminescence intensity of the CQB layer under both high and low current driving conditions, optimizing the luminescence intensity ratio between the two CQB layers. Consequently, in its native luminescence state without phosphor conversion, the device's color coordinates are closer to the predetermined target region, significantly improving the device's color rendering performance.

[0009] Other features and beneficial effects of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing this application. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of the present invention; Figure 2 , Figure 3 This is a schematic diagram of the structure of a light-emitting diode provided in other embodiments of the present invention; Figures 4-11 These are schematic diagrams of different variations of the active layer provided in the embodiments of the present invention; Figure 12 This is a SIMS diagram showing the distribution of different elements in the active layer along the depth direction, provided by an embodiment of the present invention.

[0012] Figure label: 10. Substrate; 20. Epitaxial stack; 21. N-type semiconductor layer; 211. Highly doped electron supply layer; 22. Active layer; 23. P-type semiconductor layer; 221. Type I quantum well layer; 221a. First barrier layer; 221b. First well layer; 222. Type II quantum well layer; 222a. Second barrier layer; 222b. Second well layer; 223. Transition layer; 24. Stress relief layer; 30. Electron blocking layer; 41. First electrode; 42. Second electrode. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings; the technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0014] It should also be noted that the dimensions and thicknesses in the accompanying drawings are merely examples and not intended to limit the specific technical solution of the present invention. The parameters such as length, width, height, thickness, angles, and relative dimensional proportions between components presented in the drawings are solely for the purpose of more clearly and intuitively illustrating the structural composition, connection relationships, and working principle of the present invention, facilitating understanding of the inventive concept by those skilled in the art, and not for limiting the scope of protection of the present invention to the dimensions shown in the examples. In actual implementation of this application, the dimensions and thicknesses shown in the drawings can be reasonably adjusted, optimized, or replaced according to the needs of specific application scenarios. As long as such adjustments do not deviate from the technical principles and core inventive points disclosed in this application, they should all fall within the scope of protection of this application.

[0015] This application provides a light-emitting diode (LED) comprising: an epitaxial stack 20 and a transition layer 223; the epitaxial stack 20 includes an N-type semiconductor layer 21, a P-type semiconductor layer 23, and an active layer 22 located between the N-type semiconductor layer 21 and the P-type semiconductor layer 23; the active layer 22 includes a first type quantum well layer 221 and a second type quantum well layer 222, wherein the In concentration of the first type quantum well layer 221 is greater than the In concentration of the second type quantum well layer 222, and the first type quantum well layer 221 is closer to the N-type semiconductor layer 21 than the second type quantum well layer 222; the transition layer 223 is located between the first type quantum well layer 221 and the second type quantum well layer 222.

[0016] Furthermore, the first type of quantum well layer 221 is located in the active layer 22 at the position closest to the N-type semiconductor layer 21.

[0017] Furthermore, the second type of quantum well layer 222 is located at the position of the active layer 22 closest to the P-type semiconductor layer 23.

[0018] Further, the distance h1 between the first type of quantum well layer 221 and the N-type semiconductor layer 21 is less than or equal to 2000 angstroms; or, the N-type semiconductor layer 21 includes a highly doped electron supply layer 211, and the distance h3 between the first type of quantum well layer 221 and the highly doped electron supply layer 211 is less than or equal to 2000 angstroms.

[0019] Further, the distance h2 between the second type of quantum well layer 222 and the N-type semiconductor layer 21 is greater than or equal to 4000 angstroms; or, the N-type semiconductor layer 21 includes a highly doped electron supply layer 211, and the distance h4 between the second type of quantum well layer 222 and the highly doped electron supply layer 211 is greater than or equal to 4000 angstroms.

[0020] Furthermore, the distance h1 between the first type of quantum well layer 221 and the N-type semiconductor layer 21 and the distance h2 between the second type of quantum well layer 222 and the N-type semiconductor layer 21 satisfy the following: Alternatively, the N-type semiconductor layer 21 includes a highly doped electron supply layer 211, and the distance h3 between the first type quantum well layer 221 and the highly doped electron supply layer 211 and the distance h4 between the second type quantum well layer 222 and the highly doped electron supply layer 211 satisfy the following: .

[0021] Furthermore, the thickness of the transition layer 223 is between 4000 angstroms and 8000 angstroms.

[0022] Furthermore, the transition layer 223 is an unintentionally doped P-type layer structure, and the P-type doping concentration is lower than […]. .

[0023] Furthermore, the transition layer 223 is an N-type doped transition layer or an unintentionally doped transition layer; when the transition layer 223 is an N-type doped transition layer, the N-type doping concentration of the N-type doped transition layer is between Or, the N-type doping concentration of the N-type doped transition layer is between .

[0024] Furthermore, the first type of quantum well layer 221 includes a periodic structure formed by alternating stacking of a first well layer 221b and a first barrier layer 221a, and the second type of quantum well layer 222 includes a periodic structure formed by alternating stacking of a second well layer 222b and a second barrier layer 222a; both the first barrier layer 221a and the second barrier layer 222a are doped with Al, and the Al doping concentration of the first barrier layer 221a is lower than the Al doping concentration of the second barrier layer 222a; or, the first barrier layer 221a is not doped with Al or is unintentionally doped with Al.

[0025] Furthermore, the total thickness of the first type of quantum well layer 221 in the active layer 22 is less than or equal to the total thickness of the second type of quantum well layer 222 in the active layer 22.

[0026] Furthermore, the first type of quantum well layer 221 includes a periodic structure formed by alternating stacking of a first well layer 221b and a first barrier layer 221a, and the second type of quantum well layer 222 includes a periodic structure formed by alternating stacking of a second well layer 222b and a second barrier layer 222a; the thickness of the first well layer 221b is less than the thickness of the second well layer 222b, and / or the thickness of the first barrier layer 221a is greater than the thickness of the second barrier layer 222a.

[0027] Further, the thickness of the first well layer 221b is between 10 angstroms and 40 angstroms; and / or, the thickness of the first barrier layer 221a is between 80 angstroms and 150 angstroms; and / or, the thickness of the second well layer 222b is between 10 angstroms and 50 angstroms; and / or, the thickness of the second barrier layer 222a is between 80 angstroms and 150 angstroms.

[0028] Furthermore, the first type of quantum well layer 221 includes a periodic structure formed by alternating stacking of a first well layer 221b and a first barrier layer 221a, and the second type of quantum well layer 222 includes a periodic structure formed by alternating stacking of a second well layer 222b and a second barrier layer 222a; the total number of periods in the first type of quantum well layer 221 is 1 to 15, and the total number of periods in the second type of quantum well layer 222 is 1 to 15.

[0029] Furthermore, the first type of quantum well layer 221 includes a periodic structure formed by alternating stacking of a first well layer 221b and a first barrier layer 221a, and the second type of quantum well layer 222 includes a periodic structure formed by alternating stacking of a second well layer 222b and a second barrier layer 222a; the Si doping concentration of the first barrier layer 221a is greater than the Si doping concentration of the second barrier layer 222a.

[0030] Furthermore, the ratio of the Si doping concentration of the first barrier layer 221a to the Si doping concentration of the second barrier layer 222a is greater than 1.05.

[0031] Furthermore, the Si doping concentration in the first type of quantum well layer 221 is lower than the Si doping concentration in the N-type semiconductor layer 21.

[0032] Furthermore, the transition layer 223 is an N-type doped transition layer or an unintentionally doped transition layer; when the transition layer 223 is an N-type doped transition layer, the Si doping concentration in at least a portion of the N-type doped transition layer is greater than or equal to... ; and / or, the Si doping concentration in the N-type doped transition layer is less than the Si doping concentration in the N-type semiconductor layer 21.

[0033] Furthermore, the first type of quantum well layer 221 is a green light quantum well layer, and the second type of quantum well layer 222 is a blue light quantum well layer.

[0034] This application also provides a light-emitting device that employs a light-emitting diode as described in any of the above embodiments to effectively improve the color rendering performance of the light-emitting device.

[0035] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application and through various specific implementation methods.

[0036] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a light-emitting diode in one embodiment of this application. To achieve at least one or more of the aforementioned advantages, one embodiment of this application provides a light-emitting diode that includes at least an epitaxial stack 20 and a transition layer 223.

[0037] The epitaxial stack 20 is formed on the substrate 10, which can be a conductive substrate or a non-conductive substrate, or a transparent substrate or a non-transparent substrate. For example, the substrate 10 can be sapphire (Al2O3), silicon carbide (SiC), silicon (Si), magnesium oxide (MgO), aluminum gallium oxide (LiGaO2), or gallium nitride (GaN), and this embodiment is not limited thereto. In some embodiments, the substrate 10 can be thinned or removed in subsequent processes.

[0038] Furthermore, the upper and lower positions mentioned above in this specification are defined by the position of the substrate 10. It is assumed that the direction closer to the substrate 10 is lower, and the direction farther from the substrate 10 is upper. The upper and lower position settings in this specification are only for illustrating the positional relationship of the components in the illustrated embodiments and do not represent an indication or imply that they must have a specific orientation.

[0039] The epitaxial stack 20 can be formed on the substrate 10 by methods such as metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydride vapor deposition (HVPE), physical vapor deposition (PVD), or ion plating. A buffer layer can also be formed between the substrate 10 and the epitaxial stack 20. The buffer layer can be a single layer or a composite layer structure, and can be made of conductive material, or can be a transparent or opaque material.

[0040] The epitaxial stack 20 can provide light with a specific central emission wavelength, such as blue-green light. Figure 1In the illustrated embodiment, the epitaxial stack 20 includes an N-type semiconductor layer 21, a P-type semiconductor layer 23, and an active layer 22 located between the N-type semiconductor layer 21 and the P-type semiconductor layer 23. The stacking arrangement can be flexibly designed according to actual needs: it can be that the N-type semiconductor layer, the active layer 22, and the P-type semiconductor layer are formed sequentially on the substrate 10, or it can be that the P-type semiconductor layer, the active layer 22, and the N-type semiconductor layer are formed sequentially on the substrate 10. This application does not limit this arrangement.

[0041] The N-type semiconductor layer 21 can provide electrons to the active layer 22 under the influence of a power source. In some embodiments, the N-type semiconductor layer 21 can be N-type doped AlGaInP, AlGaAs, or other materials belonging to the same system as these two, such as an N-type GaN layer. The P-type semiconductor layer 23 can provide holes to the active layer 22 under the influence of a power source. In some embodiments, the P-type semiconductor layer 23 includes a P-type doped nitride layer, a phosphide layer, or an arsenide layer. The P-type doped nitride layer, phosphide layer, or arsenide layer may include one or more P-type impurities of group II elements. The P-type impurities may be one or a combination of Mg, Zn, and Be. Both the N-type semiconductor layer 21 and the P-type semiconductor layer 23 can be single-layer structures or multi-layer structures with different compositions.

[0042] The active layer 22 is a multiple quantum well (MQW) structure composed of periodically alternating well and barrier layers. In some embodiments, the active layer 22 may include a multiple quantum well structure composed of materials such as GaN, AlGaN, InAlGaN, InGaN, InGaAS, AlGaAs, GaInP, AlGaInP, and AlInP. To improve the luminescence efficiency of the active layer 22, the depth of the quantum wells, the number of paired quantum wells and quantum barriers, the thickness, and / or other characteristics can be changed in the active layer 22. As an example, the barrier layer is a GaN layer or an AlGaN layer, and the well layer is an InGaN layer.

[0043] Of course, the configuration of the epitaxial stack 20 is not limited to this. Other functional structural layers that optimize the performance of the light-emitting element can be selected according to actual needs, such as the stress relief layer 24 or the ohmic contact layer. For example, please refer to... Figure 2 The epitaxial stack 20 also includes an electron blocking layer 30 located between the P-type semiconductor layer 23 and the active layer 22 to effectively block electron overflow, forcing more electrons to remain in the active layer 22 to recombine with holes, optimizing the electron-to-hole concentration ratio in the active layer 22, reducing non-radiative recombination losses, thereby improving radiative recombination efficiency and enhancing the luminescence intensity of the device. For example, please refer to... Figure 4 , Figure 12The epitaxial stack 20 also includes a stress relief layer 24, wherein the stress relief layer 24 is located between the N-type semiconductor layer 21 and the first type quantum well layer 221 and / or between the transition layer 223 and the second type quantum well layer 222, so as to effectively alleviate the lattice mismatch stress between the active region and the adjacent semiconductor layer, reduce crystal defects caused by stress accumulation, and improve the structural stability and optoelectronic performance of the device.

[0044] Please see Figure 3 The light-emitting diode also includes a first electrode 41 and a second electrode 42, wherein the first electrode 41 is electrically connected to the N-type semiconductor layer 21; and the second electrode 42 is electrically connected to the P-type semiconductor layer 23. The first electrode 41 and the second electrode 42 may be one or a combination of materials such as chromium (Cr), titanium (Ti), tungsten (W), gold (Au), aluminum (Al), indium (In), tin (Sn), nickel (Ni), rhodium (Rh), platinum (Pt), germanium (Ge), beryllium (Be), gold-germanium (AuGe), gold-germanium-nickel (AuGeNi), beryllium gold (BeAu), and gold-zinc (AuZn).

[0045] In another embodiment, the light-emitting diode further includes an insulating protective layer (not shown in the figure), which at least covers the surface and sidewalls of the epitaxial stack 20 to provide insulation protection for the epitaxial stack 20, thereby ensuring the overall optical performance of the light-emitting diode. Optionally, the insulating protective layer is a transparent insulating layer, specifically made of the same or combined materials such as Al2O3, TiO2, SiO2, and SiN.

[0046] Based on the above structure, in this embodiment, the active layer 22 includes a first type of quantum well layer 221 and a second type of quantum well layer 222, and the In concentration of the first type of quantum well layer 221 is greater than the In concentration of the second type of quantum well layer 222, which can realize the emission of light of different wavelengths and meet the requirements of multicolor light emission. Specifically, the first type of quantum well layer 221 and the second type of quantum well layer 222 emit light of different colors.

[0047] However, due to the influence of the quantum confinement Stark effect (QCSE) and the uneven distribution of charge carriers in different quantum well layers, the design of these different quantum well layers results in an imbalance in the ratio of luminescence intensity of the two quantum well layers. This causes the color coordinates of the device to deviate from the target region in the native luminescence state without phosphor conversion, resulting in poor color rendering of the device.

[0048] Based on the above, this embodiment solves the aforementioned problem by defining the positions of the first type of quantum well layer 221, the second type of quantum well layer 222, and the transition layer 223. For details, please refer to [link / reference needed]. Figure 1The first type of quantum well layer 221 is closer to the N-type semiconductor layer 21 than the second type of quantum well layer 222. That is, the first type of quantum well layer 221 is closer to the electron supply end, while the second type of quantum well layer 222 is closer to the hole supply end.

[0049] In specific implementation, the distance between the first type of quantum well layer 221 and the N-type semiconductor layer 21 is smaller than the distance between the second type of quantum well layer 222 and the N-type semiconductor layer 21. This arrangement achieves precise control of luminescence intensity through the difference in carrier migration characteristics. Since the electron migration rate provided by the N-type semiconductor layer 21 is much higher than that provided by the P-type semiconductor layer 23, when the first type of quantum well layer 221 is close to the N-type semiconductor layer 21, the injected electrons, due to their fast migration speed, can easily pass through the potential barrier of the first type of quantum well layer 221 and diffuse deeper into the active layer 22 (i.e., move towards the second type of quantum well layer 222). In particular, when the N-type semiconductor layer 21 includes a highly doped electron supply layer 211, the proximity of the first type of quantum well layer 221 to the highly doped electron supply layer 211 can further enhance the rapid injection and penetration effect of electrons, enabling more electrons to cross the first type of quantum well layer 221 and migrate to the second type of quantum well layer 222. Holes, due to their slow migration speed, are difficult to diffuse into the first type of quantum well layer 221 and tend to remain in the second type of quantum well layer 222, which is closer to the P-type semiconductor layer 23.

[0050] This carrier distribution characteristic directly leads to a significant reduction in the recombination probability of electrons and holes in the first type of quantum well layer 221, resulting in a decrease in its luminescence brightness. The second type of quantum well layer 222, due to the accumulation of more holes and the reception of electrons diffused from the first type of quantum well layer 221, exhibits increased recombination efficiency and relatively enhanced luminescence brightness (such as blue light). This differentiated design of the near-N side layout effectively controls the luminescence intensity ratio of the two types of quantum well layers, avoiding color coordinate shifts caused by excessive luminescence from the first type of quantum well layer 221, and fundamentally improving the color rendering problem in the device's native luminescence state.

[0051] For example, please refer to Figure 5 , Figure 6 The distance h1 between the first type of quantum well layer 221 and the N-type semiconductor layer 21 is less than or equal to 2000 angstroms. That is, other semiconductor layers or functional layers can be inserted between the first type of quantum well layer 221 and the N-type semiconductor layer 21, or it can directly contact the surface of the N-type semiconductor layer 21; and by limiting the distance h1, the luminous brightness of the first type of quantum well layer 221 can be effectively reduced.

[0052] More preferably, the N-type semiconductor layer 21 includes a highly doped electron supply layer 211, and the distance h3 between the first quantum well layer 221 and the highly doped electron supply layer 211 is less than or equal to 2000 angstroms. The highly doped electron supply layer 211 can generate free electrons by high-concentration doping with donor impurities and is used to provide electrons to the active layer 22, wherein the donor impurity concentration of the highly doped electron supply layer 211 is ≥10⁻⁶. 19 cm -3 The donor impurity is selected from at least one of Si, P, As, Sb, Se, and Te. The highly doped electron supply layer 211 can be located in the middle layer of the N-type semiconductor layer 21 or at the side of the N-type semiconductor layer 21 closest to the active layer 22, depending on the actual requirements. In this embodiment, the donor impurity of the highly doped electron supply layer 211 is preferably Si. By limiting the distance h3, the transport path between the P-type semiconductor layer 23 and the N-type semiconductor layer 21 can be effectively shortened, reducing the residence time of electrons in the first type of quantum well layer 221.

[0053] For example, please refer to Figure 5 , Figure 6 The distance h2 between the second type quantum well layer 222 and the N-type semiconductor layer 21 is greater than or equal to 4000 angstroms, so that the second type quantum well layer 222 is far away from the N-type semiconductor layer 21, so that holes and electrons recombine more in the second type quantum well layer 222, thus ensuring the luminescence intensity of the second type quantum well layer 222.

[0054] More preferably, the N-type semiconductor layer 21 includes a highly doped electron supply layer 211, and the distance h4 between the second type quantum well layer 222 and the highly doped electron supply layer 211 is greater than or equal to 4000 angstroms. By limiting the distance h4, the difficulty of holes diffusing into the first type quantum well layer 221 can be further increased, so that more holes remain in the second type quantum well layer 222.

[0055] In other embodiments, the distance h1 between the first type of quantum well layer 221 and the N-type semiconductor layer 21 and the distance h2 between the second type of quantum well layer 222 and the N-type semiconductor layer 21 satisfy the following: Alternatively, the N-type semiconductor layer 21 includes a highly doped electron supply layer 211, and the distance h3 between the first type quantum well layer 221 and the highly doped electron supply layer 211 and the distance h4 between the second type quantum well layer 222 and the highly doped electron supply layer 211 satisfy the following: Through the above or The distance ratio limitation allows the first type of quantum well layer 221, which is close to the electron source, to capture only a small number of initially injected electrons. Most of the electrons will penetrate the potential barrier and gather in the second type of quantum well layer 222, which is far away, due to their higher initial kinetic energy. At the same time, holes will gather more in the second type of quantum well layer 222 due to their low migration rate. This significantly widens the spatial gradient between the two types of quantum well layers and the electron source, strengthens the differentiation of carrier distribution, and ultimately achieves reasonable control of the luminescence intensity ratio.

[0056] Based on the above, such as Figure 5 When the highly doped electron supply layer 211 is located on the side of the N-type semiconductor layer 21 closest to the active layer 22, h1=h3, h2=h4. For example... Figure 6 When the highly doped electron supply layer 211 is located in the middle layer of the N-type semiconductor layer 21, h1 < h3, h2 < h4.

[0057] In addition, please see Figures 4-11 A transition layer 223 is disposed between the first type of quantum well layer 221 and the second type of quantum well layer 222. The transition layer 223 can be made of any gallium nitride-based material, preferably GaN. If the transition layer 223 is intentionally p-type doped, the introduced holes can easily enter the first type of quantum well layer 221, leading to an increase in the brightness of the first type of quantum well layer 221. This, in turn, makes it easier for the color coordinates of the device to deviate from the preset target region in its native emission state without phosphor conversion. Therefore, in this embodiment, the transition layer 223 is preferably an unintentionally p-type doped layer structure, and the p-type doping concentration is lower than […]. .

[0058] Preferably, the transition layer 223 is an N-type doped transition layer or an unintentionally doped transition layer. Wherein, an N-type doped transition layer refers to a transition layer 223 in which the N-type doping concentration is higher than that of the N-type dopant layer. Unintentionally doped transition layers refer to transition layers 223 where the N-type doping concentration, P-type doping concentration, and Al doping concentration are all lower than [a certain value]. Compared to using an unintentionally doped transition layer, an N-type doped transition layer can reduce the forward conduction voltage of the device and has better ESD immunity. Therefore, this embodiment preferably uses an N-type doped transition layer.

[0059] When the transition layer 223 is an unintentionally doped transition layer, its specific thickness can extend the carrier migration path: holes have weak migration ability and are difficult to reach the first type of quantum well layer 221; while electrons have strong migration ability and are more likely to pass through the transition layer 223 to enter the second type of quantum well layer 222, which can realize differentiated control of the carrier recombination efficiency of the two types of quantum well layers.

[0060] When the transition layer 223 is an N-type doped transition layer, the electron enrichment characteristics of the N-type doped transition layer can be used to provide a "transmission channel" for electrons diffusing from the first type quantum well layer 221, making it easier for electrons to move towards the second type quantum well layer 222 under the guidance of the N-type doped transition layer. Furthermore, the potential barrier formed by the N-type doped transition layer can prevent holes from diffusing into the first type quantum well layer 221, making it easier for holes to accumulate in the second type quantum well layer 222. This reduces the probability of electron-hole recombination in the first type quantum well layer 221 while increasing the probability of electron-hole recombination in the second type quantum well layer 222, thereby strengthening the above-mentioned carrier distribution difference and ensuring the stability of the luminescence intensity ratio.

[0061] Based on the above-mentioned positional design of the transition layer 223, the first type of quantum well layer 221, and the second type of quantum well layer 222, the structure can effectively reduce the luminous brightness of the first type of quantum well layer 221 under both high and low current driving conditions, thereby optimizing the luminous intensity ratio of the two types of quantum well layers. This makes the color coordinates of the device closer to the preset target region in the native luminous state without phosphor conversion, significantly improving the color rendering performance of the device.

[0062] In this embodiment, the lattice constant of the transition layer 223 is preferably between that of the first type of quantum well layer 221 and the second type of quantum well layer 222, so as to alleviate the interfacial stress caused by the difference in lattice constant between the first type of quantum well layer 221 and the second type of quantum well layer 222, reduce the generation of defects such as dislocations and stress concentration, improve the overall crystal quality of the active layer 22, and ensure the stability of carrier recombination efficiency.

[0063] Preferably, the thickness of the transition layer 223 is between 4000 angstroms and 8000 angstroms. This thickness limitation allows for more effective electron guidance and hole blocking. On one hand, it avoids situations where the thickness of the transition layer 223 is less than 4000 angstroms, which weakens its electron guidance effect and leads to electrons becoming trapped near the first type of quantum well layer 221, resulting in excessively high luminescence intensity. Simultaneously, it avoids situations where a thin transition layer 223 results in excessively short hole migration paths, making it easier for holes to cross the potential barrier and enter the first type of quantum well layer 221 to participate in radiative recombination, causing excessive luminescence in the first type of quantum well layer 221 and disrupting the preset luminescence intensity ratio between different quantum well layers, thus affecting the final optical and color performance of the device. On the other hand, while a thickness exceeding 8000 angstroms allows for better control of the luminescence intensity ratio, it also increases the overall active resistance, affecting the electro-optical conversion efficiency. Therefore, by limiting the specific thickness of the transition layer 223, the optical and color performance of the device can be effectively balanced with the electro-optical conversion efficiency, thus achieving a synergistic balance between optical and color performance and electrical performance.

[0064] Furthermore, when the transition layer 223 is an N-type doped transition layer, in this embodiment, the N-type doping concentration of the N-type doped transition layer is preferably between [value missing]. More preferably, the N-type doping concentration of the N-type doped transition layer is between... The lower N-type doping concentration not only reduces the number of impurity atoms and decreases the interdiffusion between impurity atoms and In and Ga atoms in the quantum well layer, thereby effectively improving crystal quality and avoiding wavelength shift in the quantum well layer caused by compositional degradation, but also facilitates an effective transition between the lower-quality first-type quantum well layer 221 and the higher-quality second-type quantum well layer 222, reducing interference with the quantum well layer potential field.

[0065] In one embodiment, please refer to Figure 12 The Si doping concentration in at least a portion of the N-type doped transition layer is greater than or equal to... By designing a high Si doping concentration, the N-type doped transition layer becomes more defective, and V-pit structures are formed by defect induction. The V-pit structure can effectively change the propagation path of light in the active layer 22, causing the light to undergo multiple reflections and refractions at the V-pits. Some of the light that was originally confined inside the device due to total internal reflection can escape through the V-pit openings, thereby improving the light extraction efficiency of the device.

[0066] In another embodiment, while designing a high Si doping concentration in the N-type doped transition layer, it is also necessary to avoid excessive Si doping concentration. In this embodiment, it is preferred that the Si doping concentration in the N-type doped transition layer is lower than the Si doping concentration in the N-type semiconductor layer 21, so as to optimize the electron diffusion path, improve the crystal quality and barrier matching, and avoid excessive crystal defects caused by excessive Si doping concentration.

[0067] Please see Figure 8 The first type of quantum well layer 221 is located in the active layer 22, closest to the N-type semiconductor layer 21. That is, in the design of different quantum well layer positions, the first type of quantum well layer 221 with a higher In concentration is placed in the position closest to the N-type semiconductor layer 21.

[0068] This design allows electrons injected into the N-type semiconductor layer to preferentially enter the nearby first-type quantum well layer 221 and then rapidly diffuse into the active layer 22 due to their high migration speed, reducing their residence time in the first-type quantum well layer 221. At the same time, since the first-type quantum well layer 221 is far from the P-type semiconductor layer, holes need to cross more structural layers to reach it, further reducing the recombination probability of electrons and holes in the first-type quantum well layer 221, thereby suppressing its luminescence intensity and avoiding color coordinate shift caused by excessive luminescence from the high-In-concentration quantum well layer.

[0069] In another implementation, please refer to Figure 9The second type of quantum well layer 222 is closer to the p-type semiconductor layer 23 in the active layer 22 than the first type of quantum well layer 221. That is, in the design of the positions of different quantum well layers, the second type of quantum well layer 222 with a lower In concentration is placed at the position closest to the p-type semiconductor layer 23.

[0070] Through this design, holes injected into the P-type semiconductor layer 23, due to their slow migration speed, are difficult to diffuse deep into the active layer 22 and tend to accumulate more in the region near the P-type semiconductor layer 23. Meanwhile, the second type of quantum well layer 222, with its low In concentration, has a better-suited hole trapping barrier, allowing for efficient recombination of the accumulated holes with electrons diffused from the first type of quantum well layer 221, thus enhancing its luminescence intensity. Simultaneously, the second type of quantum well layer 222, with its lower In concentration, is less affected by the quantum confinement Stark effect (QCSE), maintaining stable luminescence even in the strong electric field region near the P-type semiconductor layer 23, further ensuring effective control of the luminescence intensity ratio between the two types of quantum well layers.

[0071] The above two positional designs can be implemented individually or in combination. By matching the carrier migration characteristics with the In concentration difference of the quantum well layer, the luminescence intensity of the first type of quantum well layer 221 and the second type of quantum well layer 222 can be directionally controlled, so that the color coordinates of the device in the native luminescence state are stabilized in the preset target region (such as reducing the CIE chromaticity Y value to below 0.3).

[0072] Please continue reading. Figures 4-11 The first type of quantum well layer 221 includes a periodic structure formed by alternating layers of first well layers 221b and first barrier layers 221a, and the second type of quantum well layer 222 includes a periodic structure formed by alternating layers of second well layers 222b and second barrier layers 222a. That is, in this embodiment, the first type of quantum well layer 221 is formed by alternating stacking of one or more first well layers 221b and one or more first barrier layers 221a; the second type of quantum well layer 222 is formed by alternating stacking of one or more second well layers 222b and one or more second barrier layers 222a. It should be understood that the quantum well layer can be stacked on top of the barrier layer or vice versa, depending on actual needs, and this embodiment does not limit this.

[0073] Optionally, both the first barrier layer 221a and the second barrier layer 222a are doped with Al, and the Al doping concentration of the first barrier layer 221a is lower than that of the second barrier layer 222a; or, the first barrier layer 221a is not doped with Al or is unintentionally doped with Al. Unintentional Al doping refers to an Al doping concentration below the detection limit, typically ≤ .For example Figure 12In the diagram, the blue line represents the Al doping concentration. The blue line located at the second type of quantum well layer 222 is higher than the blue line located at the first type of quantum well layer 221, indicating the difference in Al doping concentration between the two.

[0074] By differentiating the Al doping concentration as described above, the second type of quantum well layer 222 has a barrier layer with a higher Al concentration, thereby increasing the barrier height. This is beneficial for confining charge carriers within the well to emit light, increasing the brightness of the second type of quantum well layer 222. Furthermore, it allows fewer charge carriers to enter the first type of quantum well layer 221 to emit light, reducing the brightness of the first type of quantum well layer 221 and improving the ratio of their luminescence intensities. Moreover, reducing the Al doping concentration in the first type of quantum well layer 221 or unintentionally doping it with Al can reduce lattice mismatch and make the energy bands of the barrier layer and the well layer more closely match, reducing the barrier height of the first type of quantum well layer 221 and thus resulting in a more uniform distribution of charge carriers.

[0075] In one implementation, such as Figure 7 As shown, the thickness of the first well layer 221b is less than the thickness of the second well layer 222b, and / or the thickness of the first barrier layer 221a is greater than the thickness of the second barrier layer 222a.

[0076] In specific implementation, the first well layer 221b of the first type of quantum well layer 221 with a higher In concentration is relatively thin, which can reduce the carrier trapping capacity, decrease recombination luminescence, and further suppress the excessive luminescence of the first type of quantum well layer 221. Conversely, the second well layer 222b of the second type of quantum well layer 222 is relatively thick, which can expand the carrier recombination region, increase the recombination probability, effectively enhance the luminescence stability of the second type of quantum well layer 222, and effectively regulate the luminescence ratio of the two types of quantum well layers. Furthermore, the relatively thick first barrier layer 221a can guide electrons to diffuse further into the second type of quantum well layer 222, optimizing the carrier injection efficiency of the second type of quantum well layer 222.

[0077] As an example, the thickness of the first well layer 221b is between 10 angstroms and 40 angstroms, and / or the thickness of the first barrier layer 221a is between 80 angstroms and 150 angstroms, and / or the thickness of the second well layer 222b is between 10 angstroms and 50 angstroms, and / or the thickness of the second barrier layer 222a is between 80 angstroms and 150 angstroms.

[0078] In another embodiment, the total number of periods in the first type of quantum well layer 221 is 1 to 15, and the total number of periods in the second type of quantum well layer 222 is 1 to 15. Here, "number of periods" refers to the number of complete repeating units formed by alternating stacked well and barrier layers (i.e., 1 period = 1 well layer + 1 barrier layer). By flexibly configuring the number of periods in the two types of quantum well layers, different light color requirements and device power levels can be accommodated. For example... Figure 10In the example, the number of periods in both the first type quantum well layer 221 and the second type quantum well layer 222 is 1. Figure 11 As shown, the first type of quantum well layer 221 has 6 periods, and the second type of quantum well layer 222 has 8 periods. Of course, the specific number of periods can be reasonably designed according to actual needs, and this embodiment does not limit it.

[0079] Furthermore, such as Figure 10 As shown, in this embodiment, the total thickness of the first type of quantum well layer 221 in the active layer 22 is preferably less than or equal to the total thickness of the second type of quantum well layer 222 in the active layer 22. Specifically, the thickness difference can be achieved by setting the total number of periods of the first type of quantum well layer 221 to be less than or equal to the total number of periods of the second type of quantum well layer 222. Alternatively, the thickness difference can be achieved by setting the thickness of a single period of the first quantum well layer to be less than or equal to the thickness of a single period of the second type of quantum well layer 222, combined with the number of periods. The specific thickness can be reasonably limited according to actual needs. By limiting the thickness, the luminous intensity ratio is improved, the color coordinates are optimized, and the crystal quality and carrier utilization efficiency of the active layer 22 are enhanced.

[0080] Preferably, the Si doping concentration of the first barrier layer 221a is greater than the Si doping concentration of the second barrier layer 222a. In this embodiment, it is more preferable that the ratio of the Si doping concentration of the first barrier layer 221a to the Si doping concentration of the second barrier layer 222a is greater than 1.05. For example... Figure 12 In the diagram, the yellow line represents the Si doping concentration. The yellow line located at the first type of quantum well layer 221 is higher than the yellow line located at the second type of quantum well layer 222, indicating that the Si doping concentration in the first type of quantum well layer 221 is greater than the Si doping concentration in the second type of quantum well layer 222.

[0081] In specific implementation, the first barrier layer 221a has a relatively high Si doping concentration, which effectively reduces resistivity. Especially when the first barrier layer 221a is preferably thicker, the design combined with a higher Si doping concentration can significantly reduce the resistivity of the barrier layer, allowing the current to spread more uniformly laterally within the barrier layer and then be vertically injected into each quantum well, achieving a more uniform current distribution. The second barrier layer 222a has a relatively low Si doping concentration, which reduces the obstruction to carrier injection and ensures effective carrier injection into the well layer. In this embodiment, the ratio of the two Si doping concentrations is preferably greater than 1.05 to ensure a differentiated combination of electrical performance between the first barrier layer 221a and the second barrier layer 222a. The high Si concentration of the first barrier layer 221a optimizes the current spreading capability, while the low Si concentration of the second barrier layer 222a ensures carrier injection efficiency. The synergistic effect of these two layers can further improve the luminescence intensity ratio of the two types of quantum well layers, reduce color coordinate shifts caused by uneven current distribution or carrier injection imbalance, and improve the device's luminescence stability.

[0082] Preferably, the Si doping concentration in the first type of quantum well layer 221 is lower than the Si doping concentration in the N-type semiconductor layer 21. For example Figure 12 In the diagram, the yellow line representing the Si doping concentration is at a higher height at the N-type semiconductor layer 21 than at the first-type quantum well layer 221.

[0083] In practice, the N-type semiconductor layer mainly provides electrons through a highly doped electron supply layer 211 with high Si doping to achieve high conductivity. However, its lattice constant will be slightly distorted due to the introduction of Si atoms. Therefore, designing the Si doping concentration in the first-type quantum well layer 221 to be lower than the Si doping concentration in the N-type semiconductor layer 21 can effectively reduce lattice defects, optimize the crystal integrity of the active layer 22, improve interface quality, and reduce the adverse effects of defects on light emission performance.

[0084] Based on the above concept, in this embodiment, the first type of quantum well layer 221 is preferably a green quantum well layer, and the second type of quantum well layer 222 is a blue quantum well layer. The wavelength range of the green quantum well layer is between 510 nm and 570 nm, and the wavelength range of the blue quantum well layer is between 430 nm and 485 nm.

[0085] By limiting the various implementation methods described above, the luminous intensity of green light under low current is reduced, effectively alleviating the problem of imbalance in the ratio of luminous intensity of blue and green light caused by the quantum confinement Stark effect and uneven distribution of charge carriers in different quantum wells in light-emitting diodes where blue and green light coexist. This avoids excessively large x and y values ​​in the CIE chromaticity coordinates, resulting in a green color, and ensures that the entire light-emitting diode reaches the preset CIE coordinate range.

[0086] To effectively illustrate the technical effects of the above embodiments, this embodiment takes the first type of quantum well layer 221 as a green light quantum well layer, the second type of quantum well layer 222 as a blue light quantum well layer, and the transition layer 223 as an N-type doped transition layer as an example. Tests were conducted on quantum well layers with different stacking methods under a current condition of 30mA, and the results are shown in the following table:

[0087] As shown in the table above, the first group of experiments represents a structure without an N-type doped transition layer in existing conventional designs. In this structure, the Y-value of the CIE chromaticity coordinates is high (0.69), and the ratio of blue to green light intensity is very low (0.09). That is, the first group of experiments exhibits an excessively high proportion of green light under low current driving, causing the chromaticity coordinates to deviate from the preset target region, resulting in poor color rendering. This clearly demonstrates the problem of unbalanced luminescence intensity ratios in existing multi-quantum-well layer structures due to the quantum confinement Stark effect (QCSE) and uneven carrier distribution.

[0088] In the second group of experiments, the green quantum well layer in this application's embodiment is closer to the N-type semiconductor layer 21 than the blue quantum well layer, and an N-type doped transition layer is provided between the two green quantum well layers. In this structure, the Y-value of the CIE set coordinate is significantly reduced compared to the first group, and the blue-green light intensity ratio is greatly increased. It is evident that by coordinating the positions of the N-type doped transition layer and the green and blue quantum well layers, blue light emission is effectively enhanced, green light emission is reduced, and the blue-green light intensity ratio is significantly increased. In the native emission state, it is easier to approach the target color coordinate, thus improving color rendering. Similarly, the third and fourth groups of experiments differ from the second group in the number of green and blue quantum well layers. Even with an increase in the number, a significant difference in the number, or a small difference in the number, the Y-value of the CIE set coordinate is effectively reduced compared to the first group, and the blue-green light intensity ratio is effectively increased, improving blue-green light emission. Therefore, this also highlights the importance of the design of the transition layer 223. This design not only does not limit the number of green and blue quantum well layers, but also ensures a high ratio of blue and green light intensity while making the color coordinates more closely match the preset target, effectively mitigating the adverse effects of quantum confinement Stark effect (QCSE) and uneven carrier distribution.

[0089] This application also provides a light-emitting device, which uses the light-emitting diode provided in any of the above embodiments. Its specific structure and technical effects can be referred to the foregoing embodiments, and will not be repeated here.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light-emitting diode, characterized in that, The light-emitting diode includes: An epitaxial stack, the epitaxial stack comprising an N-type semiconductor layer, a P-type semiconductor layer, and an active layer located between the N-type semiconductor layer and the P-type semiconductor layer; The active layer includes a first type of quantum well layer and a second type of quantum well layer, and the first type of quantum well layer is closer to the N-type semiconductor layer than the second type of quantum well layer. The distance h1 between the first type of quantum well layer and the N-type semiconductor layer and the distance h2 between the second type of quantum well layer and the N-type semiconductor layer satisfy the following: .

2. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer is located in the active layer at the position closest to the N-type semiconductor layer.

3. The light-emitting diode according to claim 1, characterized in that: The second type of quantum well layer is located in the active layer at the position closest to the P-type semiconductor layer.

4. The light-emitting diode according to claim 1, characterized in that: The distance h1 between the first type of quantum well layer and the N-type semiconductor layer is less than or equal to 2000 angstroms; or, the N-type semiconductor layer includes a highly doped electron supply layer, and the distance h3 between the first type of quantum well layer and the highly doped electron supply layer is less than or equal to 2000 angstroms.

5. The light-emitting diode according to claim 1, characterized in that: The distance h2 between the second type of quantum well layer and the N-type semiconductor layer is greater than or equal to 4000 angstroms; or, the N-type semiconductor layer includes a highly doped electron supply layer, and the distance h4 between the second type of quantum well layer and the highly doped electron supply layer is greater than or equal to 4000 angstroms.

6. The light-emitting diode according to claim 1, characterized in that: The N-type semiconductor layer includes a highly doped electron supply layer, and the distance h3 between the first type of quantum well layer and the highly doped electron supply layer and the distance h4 between the second type of quantum well layer and the highly doped electron supply layer satisfy the following: .

7. The light-emitting diode according to claim 1, characterized in that: The In concentration of the first type of quantum well layer is greater than the In concentration of the second type of quantum well layer.

8. The light-emitting diode according to claim 1, characterized in that: It also includes a transition layer located between the first type of quantum well layer and the second type of quantum well layer; the transition layer is an N-type doped transition layer or an unintentionally doped transition layer.

9. The light-emitting diode according to claim 7, characterized in that: The thickness of the transition layer is between 4000 angstroms and 8000 angstroms.

10. The light-emitting diode according to claim 7, characterized in that: The transition layer is an unintentionally doped P-type layer structure, and the P-type doping concentration is lower than […]. .

11. The light-emitting diode according to claim 7, characterized in that: When the transition layer is an N-type doped transition layer, the N-type doping concentration of the N-type doped transition layer is between Or, the N-type doping concentration of the N-type doped transition layer is between .

12. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer includes a periodic structure formed by alternating stacking of a first well layer and a first barrier layer, and the second type of quantum well layer includes a periodic structure formed by alternating stacking of a second well layer and a second barrier layer; both the first barrier layer and the second barrier layer are doped with Al, and the Al doping concentration of the first barrier layer is lower than that of the second barrier layer; or, the first barrier layer is not doped with Al or is unintentionally doped with Al.

13. The light-emitting diode according to claim 1, characterized in that: The total thickness of the first type of quantum well layer in the active layer is less than or equal to the total thickness of the second type of quantum well layer in the active layer.

14. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer includes a periodic structure formed by alternating stacking of a first well layer and a first barrier layer, and the second type of quantum well layer includes a periodic structure formed by alternating stacking of a second well layer and a second barrier layer; the thickness of the first well layer is less than the thickness of the second well layer, and / or the thickness of the first barrier layer is greater than the thickness of the second barrier layer.

15. The light-emitting diode according to claim 14, characterized in that: The thickness of the first well layer is between 10 angstroms and 40 angstroms; and / or, the thickness of the first barrier layer is between 80 angstroms and 150 angstroms; and / or, the thickness of the second well layer is between 10 angstroms and 50 angstroms; and / or, the thickness of the second barrier layer is between 80 angstroms and 150 angstroms.

16. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer includes a periodic structure formed by alternating stacking of a first well layer and a first barrier layer, and the second type of quantum well layer includes a periodic structure formed by alternating stacking of a second well layer and a second barrier layer; the Si doping concentration of the first barrier layer is greater than the Si doping concentration of the second barrier layer, or the ratio of the Si doping concentration of the first barrier layer to the Si doping concentration of the second barrier layer is greater than 1.

05.

17. The light-emitting diode according to claim 1, characterized in that: The Si doping concentration in the first type of quantum well layer is lower than the Si doping concentration in the N-type semiconductor layer.

18. The light-emitting diode according to claim 8, characterized in that: When the transition layer is an N-type doped transition layer, the Si doping concentration in at least a portion of the N-type doped transition layer is greater than or equal to... And / or, the Si doping concentration in the N-type doped transition layer is less than the Si doping concentration in the N-type semiconductor layer.

19. The light-emitting diode according to any one of claims 1 to 18, characterized in that: The first type of quantum well layer is a green quantum well layer with a wavelength range of 510nm to 570nm, and the second type of quantum well layer is a blue quantum well layer with a wavelength range of 430nm to 485nm.

20. The light-emitting diode according to any one of claims 1 to 18, characterized in that: The epitaxial stack also includes an electron blocking layer, which is located between the P-type semiconductor layer and the active layer.

21. A light-emitting device, characterized in that: The light-emitting diode described in any one of claims 1 to 20 is used.

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