Light emitting diode and light emitting device

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a light-emitting diode and a light-emitting device. The light-emitting diode at least comprises an epitaxial laminated layer; the epitaxial laminated layer comprises an N-type semiconductor layer, an active layer and a P-type semiconductor layer which are laminated in sequence; the active layer comprises at least one first-class quantum well layer and at least one second-class quantum well layer, the In concentration of the first-class quantum well layer is larger than that of the second-class quantum well layer, and the first-class quantum well layer is not in direct contact with the surface of the N-type semiconductor layer. According to the light-emitting diode provided by the invention, through the position design of the first type of quantum well layer, the influence of the quantum limited stark effect on the first type of quantum well layer with relatively high In concentration can be effectively relieved, the regulation and control of the carrier injection level are improved, the luminous intensity proportion is effectively adjusted, and the color rendering property of a device is improved.

Description

Technical Field

[0001] 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

[0002] 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.

[0003] 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

[0004] 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 control the ratio of light emission 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.

[0005] In a first aspect, embodiments of this application provide a light-emitting diode, the light-emitting diode comprising an epitaxial stack; the epitaxial stack comprising a P-type semiconductor layer, an active layer and an N-type semiconductor layer stacked sequentially; the active layer comprising at least one first type quantum well layer and at least one second type quantum well layer, wherein the In concentration of the first type quantum well layer is greater than the In concentration of the second type quantum well layer, and the first type quantum well layer is not in direct contact with the surface of the N-type semiconductor layer.

[0006] This application also provides a light-emitting device that uses a light-emitting diode as described in the above embodiments.

[0007] The light-emitting diode provided in this application has a first type of quantum well layer with a high In concentration and a second type of quantum well layer with a low In concentration. The first type of quantum well layer is designed not to be in direct contact with the surface of the N-type semiconductor layer. This enables the emission of light of different wavelengths while reducing the lattice mismatch stress concentration induced by the direct interface between the N-type semiconductor layer and the first type of quantum well layer with a high In concentration. This helps to alleviate the quantum confinement Stark effect (QCSE), improve the distribution of charge carriers in the first type of quantum well layer, optimize the ratio of the luminous intensity of the two types of quantum well layers, and make the color coordinates of the device in the native luminous state closer to the target region, effectively improving color rendering.

[0008] 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

[0009] 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.

[0010] Figure 1 This is a schematic diagram of the structure of a light-emitting diode in one embodiment of the present invention; Figure 2 , Figure 3 This is a schematic diagram of the structure of a light-emitting diode in other embodiments provided by 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.

[0011] Figure label: 10. Substrate; 20. Epitaxial stack; 21. N-type semiconductor layer; 22. Active layer; 23. P-type semiconductor layer; 221. First type quantum well layer; 221a. First barrier layer; 221b. First well layer; 222. Second type quantum well layer; 222a. Second barrier layer; 222b. Second well layer; 22c. Transition barrier layer; 30. Electron blocking layer; 41. First electrode; 42. Second electrode. Detailed Implementation

[0012] 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.

[0013] This application provides a light-emitting diode, the light-emitting diode comprising: an epitaxial stack 20; the epitaxial stack 20 comprising an N-type semiconductor layer 21, an active layer 22 and a P-type semiconductor layer 23 stacked sequentially; The active layer 22 includes at least one first type quantum well layer 221 and at least one second type quantum well layer 222. 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 not in direct contact with the surface of the N-type semiconductor layer 21.

[0014] The above settings help to alleviate the quantum confinement Stark effect, improve the distribution of charge carriers in the first type of quantum well layer 221, optimize the ratio of luminescence intensity of the two types of quantum well layers, and make the color coordinates of the device in the native luminescence state closer to the target region, thus effectively improving color rendering.

[0015] Furthermore, at least one second-type quantum well layer 222 is located in the active layer 22 at the position closest to the N-type semiconductor layer 21.

[0016] Furthermore, at least one second-type quantum well layer 222 is located closer to the N-type semiconductor layer 21 in the active layer 22 than the first-type quantum well layer 221.

[0017] Furthermore, in at least one first-type quantum well layer 221, the Mg doping concentration is greater than the Si doping concentration; both the Mg doping concentration and the Si doping concentration in the at least one first-type quantum well layer 221 are greater than or equal to 10. 17 cm -3 .

[0018] Furthermore, the Si doping concentration in at least one of the first type of quantum well layers 221 is between 10⁻⁶ and 10⁻⁶. 17 cm -3 ~10 18 cm -3 .

[0019] Furthermore, the first type of quantum well layer 221 includes alternating layers of a first well layer 221b and a first barrier layer 221a, and the second type of quantum well layer 222 includes alternating layers of a second well layer 222b and a second barrier layer 222a; the Al doping concentration of at least one first barrier layer 221a is less than the Al doping concentration of at least one second barrier layer 222a.

[0020] Furthermore, the first type of quantum well layer 221 includes alternating layers of a first well layer 221b and a first barrier layer 221a, and the second type of quantum well layer 222 includes alternating layers of a second well layer 222b and a second barrier layer 222a; the thickness of the first well layer 221b and the thickness of the second well layer 222b differ by less than or equal to 20 angstroms, and / or the ratio of the thickness of the first well layer 221b to the thickness of the second well layer 222b is between 1 and 1.3.

[0021] Furthermore, the first type of quantum well layer 221 includes alternating layers of a first well layer 221b and a first barrier layer 221a, and the second type of quantum well layer 222 includes alternating layers of a second well layer 222b and a second barrier layer 222a; the Si concentration of the first barrier layer 221a is greater than the Si concentration of the second barrier layer 222a, and / or the ratio of the Si concentration of the first barrier layer 221a to the Si concentration of the second barrier layer 222a is greater than 1.05.

[0022] Further, the first type of quantum well layer 221 includes alternating layers of first well layer 221b and first barrier layer 221a, and the second type of quantum well layer 222 includes alternating layers of second well layer 222b and second barrier layer 222a; wherein, in the first type of quantum well layer 221 adjacent to the second type of quantum well layer 222, the thickness of the first barrier layer 221a directly adjacent to the second type of quantum well layer 222 is greater than the thickness of each of the other first barrier layers 221a; and / or, in the second type of quantum well layer 222 adjacent to the first type of quantum well layer 221, the thickness of the second barrier layer 222a directly adjacent to the first type of quantum well layer 221 is greater than the thickness of each of the other second barrier layers 222a.

[0023] Further, the first type of quantum well layer 221 includes alternating layers of first well layer 221b and first barrier layer 221a, and the second type of quantum well layer 222 includes alternating layers of second well layer 222b and second barrier layer 222a; a transition barrier layer 22c is provided between the first type of quantum well layer 221 and the second type of quantum well layer 222, the thickness of the transition barrier layer 22c being less than the thickness of each of the first barrier layer 221a in the active layer 22, or the thickness of the transition barrier layer 22c being less than the thickness of each of the second barrier layer 222a in the active layer 22.

[0024] Furthermore, the active layer 22 has at least one second type quantum well layer 222 located at the position closest to the P-type semiconductor layer 23, and the number of second type quantum well layers 222 located at the position closest to the P-type semiconductor layer 23 in the active layer 22 is less than or equal to the number of all first type quantum well layers 221 in the active layer 22.

[0025] Furthermore, the number of all first-type quantum well layers 221 in the active layer 22 accounts for 1 / 7 to 1 / 2 of the total number of quantum well layers in the entire active layer 22.

[0026] Furthermore, the total number of first-type quantum well layers 221 in the active layer 22 does not exceed 5 layers.

[0027] Furthermore, a transition barrier layer 22c is provided between the first type of quantum well layer 221 and the second type of quantum well layer 222, and the thickness of the transition barrier layer 22c is greater than the thickness of each barrier layer in the active layer 22.

[0028] Furthermore, in the active layer 22, when a plurality of second-type quantum well layers 222 are distributed on the side close to the N-type semiconductor layer 21 and a plurality of first-type quantum well layers 221 are distributed on the side close to the P-type semiconductor layer 23, the number of second-type quantum well layers 222 is between 5 and 15 layers, and the number of first-type quantum well layers 221 does not exceed 5 layers.

[0029] Furthermore, in the active layer 22, when a plurality of second-type quantum well layers 222 are distributed on the side near the N-type semiconductor layer 21, a plurality of second-type quantum well layers 222 are distributed on the side near the P-type semiconductor layer 23, and a plurality of first-type quantum well layers 221 are provided between the second-type quantum well layers 222 on the side near the N-type semiconductor layer 21 and the second-type quantum well layers 222 on the side near the P-type semiconductor layer 23, the number of second-type quantum well layers 222 on the side near the N-type semiconductor layer 21 is between 5 and 12 layers, the number of second-type quantum well layers 222 on the side near the P-type semiconductor layer 23 is between 0 and 3 layers, and the number of first-type quantum well layers 221 does not exceed 5 layers.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] Example 1 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.

[0034] The epitaxial stack 20 is disposed 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.

[0035] 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.

[0036] 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.

[0037] The epitaxial stack 20 can provide light with a specific central emission wavelength, such as blue or green light. Figure 1 In the illustrated embodiment, the epitaxial stack 20 includes an N-type semiconductor layer 21, an active layer 22, and a P-type semiconductor layer 23 sequentially stacked on the substrate 10; wherein the N-type semiconductor layer 21 and the P-type semiconductor layer 23 have different conductivity types, electrical properties, polarities, or are doped with elements to provide electrons or holes.

[0038] In this embodiment, the N-type semiconductor layer 21 can provide electrons to the active layer 22 under the action 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 materials. For example, in this embodiment, an N-type GaN layer is preferably used.

[0039] 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.

[0040] Under power, the P-type semiconductor layer 23 can provide holes to the active layer 22. 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. The P-type semiconductor layer 23 may be a single-layer structure or a multilayer structure with different compositions.

[0041] 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 stress relief layers or ohmic contact layers. 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, force more electrons to remain in the active layer 22 to recombine with holes, optimize the concentration ratio of electrons and holes in the active layer 22, reduce non-radiative recombination loss, thereby improving radiative recombination efficiency and enhancing the luminous intensity of the device.

[0042] 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).

[0043] 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.

[0044] Based on the above structure, in this embodiment, the active layer 22 includes at least one first-type quantum well layer 221 and at least one second-type quantum well layer 222, and 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, which enables the emission of light of different wavelengths and meets the requirements for multicolor light emission. Specifically, the first-type quantum well layer 221 and the second-type quantum well layer 222 emit light of different colors.

[0045] 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.

[0046] Based on the above, this embodiment solves the aforementioned problem by defining the position of the first type of quantum well layer 221 with a high In concentration. For details, please refer to [link / reference needed]. Figure 1 The first type of quantum well layer 221 is not in direct contact with the surface of the N-type semiconductor layer 21. That is, other quantum well layers are disposed between the first type of quantum well layer 221 and the N-type semiconductor layer 21, and the other quantum well layers may include the second type of quantum well layer 222.

[0047] By distributing the first type quantum well layer 221 relatively far away from the N-type semiconductor layer 21, the direct influence of the N-type semiconductor layer 21 on the first type quantum well layer 221 can be reduced, which helps to alleviate the quantum confinement Stark effect (QCSE) and improve the distribution state of charge carriers in the first type quantum well layer 221.

[0048] Especially under low current driving, the light emission is mainly concentrated in the quantum well near the N-type semiconductor layer 21. By setting the first type quantum well layer 221 in a position that does not directly contact the surface of the N-type semiconductor layer 21, the light emission intensity of the first type quantum well layer 221 can be effectively reduced. The light emission intensity of the first type quantum well layer 221 and the second type quantum well layer 222 can be controlled to avoid the problem of the color coordinate deviating from the preset target area due to the first type quantum well layer 221 being too bright when driven by low current. This ensures that the color coordinate of the device in the native light emission state is closer to the target area, effectively improving the color rendering performance.

[0049] Please see Figure 4 At least one second-type quantum well layer 222 is located in the active layer 22 closest to the first semiconductor. That is, in the design of different quantum well layer positions, the second-type quantum well layer 222 with a lower In concentration is placed in the position closest to the N-type semiconductor layer 21.

[0050] In an alternative embodiment, please refer to Figure 5 At least one second-type quantum well layer 222 is located closer to the N-type semiconductor layer 21 in the active layer 22 than the first-type quantum well layer 221. That is, at least one second-type quantum well layer 222 is disposed between the N-type semiconductor layer 21 and the first-type quantum well layer 221.

[0051] By distributing at least one type-2 quantum well layer 222 closer to the N-type semiconductor layer 21, the effects of the quantum confinement Stark effect can be further mitigated, carrier distribution optimized, and luminescence efficiency improved. Specifically, due to the lower In concentration of the type-2 quantum well layer 222, its sensitivity to electric fields is relatively weak. Even in the strong electric field region close to the N-type semiconductor layer 21, the luminescence performance is less negatively affected by the electric field, maintaining stable luminescence intensity and mitigating the effects of the quantum confinement Stark effect. Simultaneously, the lower In concentration of the type-2 quantum well layer 222 results in a relatively higher potential barrier. Its design effectively prevents excessive diffusion of holes out of the active layer 22, guiding holes to be more uniformly distributed within the active layer 22. This avoids the problem of excessively strong or weak luminescence in some quantum well layers due to hole concentration in a certain area, thereby controlling the luminescence ratio between the type-1 and type-2 quantum well layers 221. This further effectively avoids color coordinate shift caused by excessively high light intensity in a certain wavelength band, making the CIE chromaticity coordinates of the device's native emission closer to the target region.

[0052] Preferably, in at least one first-type quantum well layer 221, the Mg doping concentration is greater than the Si doping concentration. By limiting the Mg and Si doping concentrations as described above, the mass of the first-type quantum well layer 221 can be effectively reduced, thereby reducing the luminous intensity of the first-type quantum well layer 221 and improving the CIE chromaticity coordinate range. As an example, the Mg doping concentration and Si doping concentration in at least one first-type quantum well layer 221 are both greater than or equal to 10. 17 cm -3 This allows for reasonable control of hole and electron concentrations, reducing crystal quality. More preferably, the Si doping concentration in at least one of the first-type quantum well layers 221 is between 10⁻⁶ and 10⁻⁶. 17 cm -3 ~10 18 cm -3This is to further reduce the crystal quality and the brightness of the first type quantum well layer 221, while also avoiding excessive damage to the crystal structure caused by excessive Si doping concentration.

[0053] Based on the above concept, in this embodiment, it is further preferred that the ratio of P-type dopant concentration to N-type dopant concentration in at least one first-type quantum well layer 221 is greater than 1.05. By limiting the ratio of P-type dopant concentration to N-type dopant concentration, the concentration of holes and electrons and the crystal quality can be further controlled, thereby reducing the luminescence brightness of the first-type quantum well layer 221.

[0054] Please see Figures 4-11 The first type of quantum well layer 221 includes alternating layers of first well layer 221b and first barrier layer 221a, and the second type of quantum well layer 222 includes alternating layers of second well layer 222b and second barrier layer 222a. That is, in this embodiment, a single layer of the first type of quantum well layer 221 is formed by stacking a first well layer 221b and a first barrier layer 221a; a single layer of the second type of quantum well layer 222 is formed by stacking a second well layer 222b and a second barrier layer 222a. It should be understood that in a single quantum well layer, well layers can be stacked on top of barrier layers or barrier layers can be stacked on top of well layers, depending on actual needs. This embodiment does not limit this specific configuration.

[0055] Preferably, the Al doping concentration of the first barrier layer 221a is lower than the Al doping concentration of the second barrier layer 222a. That is, the Al doping concentration of all single-layer barrier layers in the first type of quantum well layer 221 is lower than the Al doping concentration of all single-layer barrier layers in the second type of quantum well layer 222. This limitation allows the second type of quantum well layer 222 to have 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, and allowing fewer charge carriers to enter the first type of quantum well layer 221 to emit light, thus reducing the brightness of the first type of quantum well layer 221 and modulating the brightness of both layers. Furthermore, the reduced Al doping concentration in the first type of quantum well layer 221 allows for a better match between the energy bands of the barrier layer and the energy bands of the well layer, reducing the barrier height of the first type of quantum well layer 221 and resulting in a more uniform distribution of charge carriers.

[0056] Optionally, the thickness of the first well layer 221b differs from the thickness of the second well layer 222b by less than or equal to 20 angstroms. That is, the thickness of each individual first well layer 221b in the first type of quantum well layer 221 differs from the thickness of each individual second well layer 222b in the second type of quantum well by no more than 20 angstroms. By limiting the thicknesses of both layers, uneven current distribution and localized overheating caused by excessive thickness differences can be effectively avoided, ensuring device reliability. For example, Figure 1 The thickness of the first well layer 221b in the middle monolayer is equal to the thickness of the second well layer 222b in the middle monolayer. Figure 4 The thickness of the first well layer 221b in the middle monolayer is greater than the thickness of the second well layer 222b in the middle monolayer. Figure 5 The thickness of the first monolayer 221b is equal to the thickness of the second monolayer 222b. Preferably, in this embodiment, the thickness of each first monolayer 221b in the first type of quantum well layer 221 is greater than or equal to the thickness of each second monolayer 222b in the second type of quantum well layer 222; more preferably, the thickness of the first monolayer 221b is greater than the thickness of the second monolayer 222b. This thickness limitation appropriately compensates for the luminous brightness of the first type of quantum well layer 221, preventing it from becoming too dim. As an example, the ratio of the thickness of the first well layer 221b to the thickness of the second well layer 222b is between 1 and 1.3, for example, 1, 1.05, 1.1, 1.15, 1.2, 1.25, and 1.3. On the one hand, it can prevent the brightness of the first type of quantum well layer 221 from being too small, thus failing to achieve balanced light emission with the second type of quantum well layer 222; on the other hand, it can avoid the problem that the brightness of the first type of quantum well layer 221 is too high due to an excessively large ratio, thereby causing the overall color coordinates of the device to deviate from the target area, and ultimately achieve stable control of the light emission intensity ratio of the two types of quantum well layers.

[0057] In one embodiment, the Si concentration of the first barrier layer 221a is greater than the Si concentration of the second barrier layer 222a, and / or the ratio of the Si concentration of the first barrier layer 221a to the Si concentration of the second barrier layer 222a is greater than 1.05.

[0058] In specific implementations, the high Si concentration of the first barrier layer 221a in the first type of quantum well layer 221 effectively reduces resistivity. Especially when the first barrier layer 221a in the first type of quantum well layer 221 is preferably thicker, the combination with a higher Si concentration significantly reduces the resistivity of the barrier layer, allowing current to spread more uniformly laterally within the barrier layer before being vertically injected into each quantum well, achieving a more uniform current distribution. Conversely, the relatively low Si concentration of the second barrier layer 222a in the second type of quantum well layer 222 reduces obstacles to carrier injection, ensuring effective carrier injection into the well layer. In this embodiment, the ratio of Si concentration of the two layers is preferably greater than 1.05 to ensure that the two types of barrier layers form a differentiated combination in terms of electrical performance. The high Si concentration of the first barrier layer 221a optimizes the current spread capability, while the low Si concentration of the second barrier layer 222a ensures the carrier injection efficiency. The synergistic effect of the two layers can further regulate the luminescence intensity of the two types of quantum well layers, reduce the color coordinate shift caused by uneven current distribution or carrier injection imbalance, and improve the luminescence stability of the device.

[0059] Further, please refer to Figure 9 , Figure 10In the first type of quantum well layer 221 adjacent to the second type of quantum well layer 222, the thickness of the first barrier layer 221a directly adjacent to the second type of quantum well layer 222 is greater than the thickness of each of the other first barrier layers 221a; and / or, in the second type of quantum well layer 222 adjacent to the first type of quantum well layer 221, the thickness of the second barrier layer 222a directly adjacent to the first type of quantum well layer 221 is greater than the thickness of each of the other second barrier layers 222a.

[0060] In specific implementation, the thickness of the directly adjacent first barrier layer 221a and / or second barrier layer 222a (i.e., the barrier layer between the two types of quantum well layers) can be set to 8nm~18nm, while the thickness of the other first barrier layers 221a and second barrier layers 222a in the active layer 22 is set to 8nm~15nm. The first type of quantum well layer 221 and the second type of quantum well layer 222 have significantly different lattice constants due to the large difference in In concentration. When directly adjacent, they are prone to lattice mismatch stress at the interface. By designing the barrier layer between the two types of quantum well layers to be relatively thick, this interface stress concentration can be effectively alleviated, crystal defects reduced, and crystal quality improved. Simultaneously, a thicker barrier layer design can form a higher potential barrier, allowing more charge carriers to concentrate within the second quantum well layer, optimizing the charge carrier confinement capability, and thus improving the radiative recombination efficiency within the second quantum well layer. Especially for the first type of quantum well layer 221 with a higher In concentration, its emitted light is more easily absorbed by the surrounding material. In addition, a thicker spacer layer can enhance the structural buffering effect between the two types of quantum well layers, and better resist shock stress.

[0061] In an alternative implementation, please refer to Figure 11 A transition barrier layer 22c is provided between the first type of quantum well layer 221 and the second type of quantum well layer 222. The thickness of the transition barrier layer 22c is less than the thickness of each of the first barrier layers 221a in the active layer 22, or the thickness of the transition barrier layer 22c is less than the thickness of each of the second barrier layers 222a in the active layer 22. As an example, the thickness of the transition barrier layer 22c is no greater than 30 angstroms to ensure good performance. In this embodiment, the transition barrier layer 22c can be doped with a low concentration of Al. That is, compared with the above-mentioned scheme of thickening the barrier layers of adjacent first type of quantum well layers 221 or second type of quantum well layers 222, this embodiment can also directly insert a thinner transition barrier layer 22c between adjacent first type of quantum well layers 221 and second type of quantum well layers 222 to achieve the same effect of improving crystal quality, restricting carrier distribution, and enhancing structural buffering.

[0062] In other embodiments, the active layer 22 has a plurality of second-type quantum well layers 222 located at the position closest to the N-type semiconductor layer 21, and the total number of the plurality of second-type quantum well layers 222 located at the position closest to the N-type semiconductor layer 21 in the active layer 22 is greater than the total number of all first-type quantum well layers 221 in the active layer 22.

[0063] In specific implementation, by combining the overall structural design of the active layer 22 with the ratio of more layers of second-type quantum well layers 222 with higher In concentration to fewer layers of first-type quantum well layers 221 with lower In concentration, the overall luminescence intensity of the second-type quantum well layer 222 can be increased, while the overall luminescence intensity of the first-type quantum well layer 221 can be reduced. This further modulates the luminescence intensity of the two types of quantum well layers, alleviates the negative impact of the quantum confinement Stark effect, and avoids color coordinate shift caused by excessive luminescence of the first-type quantum well layer 221.

[0064] As an example, the number of all first-type quantum well layers 221 in the active layer 22 accounts for 1 / 7 to 1 / 2 of the total number of quantum well layers in the active layer 22. In other words, the ratio of the number of first-type quantum well layers 221 consisting of one well layer and one barrier layer to the total number of quantum well layers consisting of one well layer and one barrier layer in the active layer 22 is between 1 / 7 and 1 / 2. That is, the number of first-type quantum well layers 221 should be less than or equal to the sum of the number of other quantum well layers. In this embodiment, it is preferred that the total number of first-type quantum well layers 221 in the active layer 22 does not exceed 5 layers. By controlling the number of first-type quantum well layers 221 as described above, the carrier injection level of the first-type quantum well layers 221 can be effectively and reasonably regulated, reducing the overall luminescence intensity of the first-type quantum well layers 221 under low current driving, while ensuring that the first-type quantum well layers 221 have their appropriate luminescence intensity.

[0065] Please see Figure 8 , Figure 11 The active layer 22 has at least one second type quantum well layer 222 located at the position closest to the P-type semiconductor layer 23, and the number of second type quantum well layers 222 located at the position closest to the P-type semiconductor layer 23 in the active layer 22 is less than or equal to the number of all first type quantum well layers 221 in the active layer 22.

[0066] In specific implementation, by setting a smaller number of second-type quantum well layers 222 closest to the P-type semiconductor layer 23, on the one hand, their barrier properties can be used to trap high-energy electrons, avoiding the distribution imbalance caused by electrons directly flooding into the active layer 22, and effectively regulating the electric field distribution; on the other hand, the lattice mismatch between the P-type semiconductor layer 23 and the second-type quantum well layer 222 is smaller than that with the first-type quantum well layer 221. This setting can effectively alleviate interface stress and improve lattice transition characteristics. At the same time, the controlled number of second-type quantum well layers 222 can avoid wavelength light over-emission, forming a complementary control with the luminescence intensity of the first-type quantum well layer 221, further ensuring that the device's primary color coordinates are stable in the target region.

[0067] 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.

[0068] 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.

[0069] Example 2 Based on the above embodiment one, please refer to Figures 6-8 In this second embodiment, the active layer 22 preferably includes only a second type quantum well layer 222 and a first type quantum well layer 221. The second type quantum well layer 222 is distributed on the side close to the N-type semiconductor layer 21, and the first type quantum well layer 221 is distributed on the side close to the P-type semiconductor layer 23, forming a "second type quantum well layer 222 / first type quantum well layer 221" structure.

[0070] In this structure, preferably, when a plurality of second-type quantum well layers 222 are distributed near the N-type semiconductor layer 21 and a plurality of first-type quantum well layers 221 are distributed near the P-type semiconductor layer 23, the number of second-type quantum well layers 222 is between 5 and 15, and the number of first-type quantum well layers 221 does not exceed 5. As an example, the number of second-type quantum well layers 222 can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, and the number of first-type quantum well layers 221 can be 1, 2, 3, 4, or 5. The specific configuration can be reasonably set according to actual needs, and this embodiment does not impose any limitations.

[0071] Example 3 Based on the above embodiment one, please refer to Figures 9-11 In this embodiment, the active layer 22 preferably includes only the first type of quantum well layer 221 and the second type of quantum well layer 222, and the stacking method from bottom to top is a plurality of second type of quantum well layers 222, a plurality of first type of quantum well layers 221 and at least one second type of quantum well layer 222, forming "second type of quantum well layer 222 / first type of quantum well layer 221 / second type of quantum well layer 222".

[0072] In this structure, preferably, the number of second-type quantum well layers 222 located between the N-type semiconductor layer 21 and the first-type quantum well layer 221 is greater than the number of first-type quantum well layers 221, while the number of second-type quantum well layers 222 located between the first-type quantum well layer 221 and the P-type semiconductor layer 23 is less than or equal to the number of first-type quantum well layers 221. That is, a larger number of second-type quantum well layers 222 are placed closer to the N-type semiconductor layer 21 to fully aggregate holes for recombination and light emission, ensuring the luminous efficiency of the second-type quantum well layers 222. A smaller number of second-type quantum well layers 222 are placed closer to the P-type semiconductor layer 23 to initially capture high-energy electrons and avoid carrier imbalance. Simultaneously, a small number of second-type quantum well layers 222 can act as an "electron transition layer," controlling the diffusion rate of electrons to the first-type quantum well layer 221 and ensuring efficient recombination of electrons and holes within the first-type quantum well layer 221. Based on this, the smaller number of first-type quantum well layers 221 located between the second-type quantum well layers 222 can effectively regulate the luminous intensity of the two types of quantum well layers and stabilize the color coordinates.

[0073] To effectively illustrate the technical effects of Embodiments 1, 2, and 3 above, this embodiment takes the first type of quantum well layer 221 as a green light quantum well layer and the second type of quantum well layer 222 as a blue light quantum well 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 table below:

[0074] As shown in the table above, the first group of experiments uses a conventional design where the green quantum well layer is positioned close to the N-type semiconductor layer 21, and the number of green quantum well layers is equal to the number of blue quantum well layers. In this structure, the CIE chromaticity coordinate Y value is high, and the ratio of blue to green light intensity is low. That is, in the first group of experiments, the proportion of green light is too high under low current driving, the chromaticity coordinate deviates from the preset target region, and the color rendering is poor. This clearly demonstrates the problem of unbalanced luminous intensity ratios in existing multi-quantum well layer structures due to the quantum confinement Stark effect (QCSE) and uneven carrier distribution.

[0075] The second group of experiments involved a structure in Embodiment 2 of this application where the green quantum well layer did not directly contact the surface of the N-type semiconductor layer 21, and the number of blue quantum well layers was greater than that of the green quantum well layers. In this structure, the Y-value of the CIE set coordinates was significantly reduced compared to the first group, and the ratio of blue to green light intensity was greatly increased. It is evident that by controlling the arrangement and number of blue and green quantum well layers, blue light emission was effectively enhanced, green light emission was reduced, and the ratio of blue to green light intensity was significantly increased. This resulted in a greater approximation of the target color coordinates in the native emission state, thus improving color rendering. Similarly, the third group of experiments involved a structure in Embodiment 3 of this application with varying stacking order and number of "blue quantum well layer / green quantum well layer / blue quantum well layer". In this structure, the Y value of the CIE set coordinates is also effectively reduced compared to the first group, and the ratio of blue-green light intensity is effectively increased. The emission of blue-green light is controlled, which not only ensures a high ratio of blue-green light intensity, but also makes the color coordinates more in line with the preset target, effectively mitigating the adverse effects of QCSE and uneven carrier distribution.

[0076] Example 4 This embodiment 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.

[0077] 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 therein. Such 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, wherein the epitaxial stack comprises an N-type semiconductor layer, an active layer and a P-type semiconductor layer stacked sequentially; The active layer includes at least one first type quantum well layer and at least one second type quantum well layer. The In concentration of the first type quantum well layer is greater than the In concentration of the second type quantum well layer, and the first type quantum well layer is not in direct contact with the surface of the N-type semiconductor layer.

2. The light-emitting diode according to claim 1, characterized in that: At least one second-type 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: At least one second-type quantum well layer is located closer to the N-type semiconductor layer in the active layer than the first-type quantum well layer.

4. The light-emitting diode according to claim 1, characterized in that: In at least one type-1 quantum well layer, the Mg doping concentration is greater than the Si doping concentration; in at least one type-1 quantum well layer, both the Mg doping concentration and the Si doping concentration are greater than or equal to 10. 17 cm -3 .

5. The light-emitting diode according to claim 1, characterized in that: The Si doping concentration in at least one of the first type of quantum well layers is between 10. 17 cm -3 ~10 18 cm -3 .

6. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer includes alternating layers of first well layer and first barrier layer, and the second type of quantum well layer includes alternating layers of second well layer and second barrier layer; the Al doping concentration of at least one first barrier layer is less than the Al doping concentration of at least one second barrier layer.

7. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer includes alternating stacked first well layers and first barrier layers, and the second type of quantum well layer includes alternating stacked second well layers and second barrier layers; the thickness of the first well layer and the thickness of the second well layer differ by less than or equal to 20 angstroms, and / or the ratio of the thickness of the first well layer to the thickness of the second well layer is between 1 and 1.

3.

8. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer includes alternating stacked first well layers and first barrier layers, and the second type of quantum well layer includes alternating stacked second well layers and second barrier layers; the Si concentration of the first barrier layer is greater than the Si concentration of the second barrier layer, and / or the ratio of the Si concentration of the first barrier layer to the Si concentration of the second barrier layer is greater than 1.

05.

9. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer includes alternating stacked first well layers and first barrier layers, and the second type of quantum well layer includes alternating stacked second well layers and second barrier layers; wherein, in the first type of quantum well layer adjacent to the second type of quantum well layer, the thickness of the first barrier layer directly adjacent to the second type of quantum well layer is greater than the thickness of each of the other first barrier layers; and / or, in the second type of quantum well layer adjacent to the first type of quantum well layer, the thickness of the second barrier layer directly adjacent to the first type of quantum well layer is greater than the thickness of each of the other second barrier layers.

10. The light-emitting diode according to claim 1, characterized in that: The first type of quantum well layer includes alternating stacked first well layers and first barrier layers, and the second type of quantum well layer includes alternating stacked second well layers and second barrier layers; there is a transition barrier layer between the first type of quantum well layer and the second type of quantum well layer, the thickness of the transition barrier layer being less than the thickness of each of the first barrier layers in the active layer, or the thickness of the transition barrier layer being less than the thickness of each of the second barrier layers in the active layer.

11. The light-emitting diode according to claim 1, characterized in that: The active layer has a plurality of second-type quantum well layers located at the position closest to the N-type semiconductor layer. The total number of the plurality of second-type quantum well layers located at the position closest to the N-type semiconductor layer in the active layer is greater than the total number of all first-type quantum well layers in the active layer.

12. The light-emitting diode according to claim 1, characterized in that: The active layer has at least one type II quantum well layer located at the position closest to the P-type semiconductor layer, and the number of type II quantum well layers located at the position closest to the P-type semiconductor layer in the active layer is less than or equal to the number of all type I quantum well layers in the active layer.

13. The light-emitting diode according to claim 1, characterized in that: The number of all type I quantum well layers in the active layer accounts for 1 / 7 to 1 / 2 of the total number of quantum well layers in the entire active layer.

14. The light-emitting diode according to claim 1, characterized in that: The total number of first-type quantum well layers in the active layer does not exceed 5.

15. The light-emitting diode according to claim 1, characterized in that: In the active layer, when several second-type quantum well layers are distributed near the N-type semiconductor layer and several first-type quantum well layers are distributed near the P-type semiconductor layer, the number of second-type quantum well layers is between 5 and 15, and the number of first-type quantum well layers does not exceed 5.

16. The light-emitting diode according to claim 1, characterized in that: In the active layer, when a plurality of second-type quantum well layers are distributed on the side near the N-type semiconductor layer, a plurality of second-type quantum well layers are distributed on the side near the P-type semiconductor layer, and a plurality of first-type quantum well layers are provided between the second-type quantum well layers on the side near the N-type semiconductor layer and the second-type quantum well layers on the side near the P-type semiconductor layer, the number of second-type quantum well layers on the side near the N-type semiconductor layer is between 5 and 12, the number of second-type quantum well layers on the side near the P-type semiconductor layer is between 0 and 3, and the number of first-type quantum well layers does not exceed 5.

17. The light-emitting diode according to any one of claims 1 to 16, characterized in that: The first type of quantum well layer is a green light quantum well layer, and the second type of quantum well layer is a blue light quantum well layer.

18. A light-emitting device, characterized in that: The light-emitting diode described in any one of claims 1-17 is used.

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