Light emitting diode and light emitting device

Abstract

The invention provides a light-emitting diode and a light-emitting device, the light-emitting diode comprises a semiconductor lamination layer, and the semiconductor lamination layer comprises a first semiconductor layer, an active layer and a second semiconductor layer which are laminated in sequence; wherein the active layer is of a quantum well structure and is provided with a plurality of pairs of potential barrier layers and potential well layers which are arranged alternately, and the potential barrier layers contain an Al component; along the growth direction of the semiconductor lamination, the average content of the Al component in at least part of the barrier layers is greater than the average content of the Al component in the next barrier layer adjacent to the barrier layers. According to the light-emitting diode with the changed Al component of the barrier layer, the violent change of an energy band close to the P-side semiconductor layer can be relieved, the constraint of two-dimensional electron gas to current carriers is avoided, holes are smoothly injected and uniformly distributed, the electron overflow phenomenon in the quantum well layer is effectively inhibited, and the light-emitting efficiency is improved. And finally, the carrier recombination efficiency and the product luminance are improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a light emitting diode and a light emitting device. Background Art

[0002] Light Emitting Diode (LED) is a semiconductor device whose basic structure includes a PN junction between a P-type semiconductor and an N-type semiconductor. When a forward voltage is applied to the LED, electrons and holes recombine at the junction of the PN junction to release energy, which is emitted in the form of photons to form light radiation.

[0003] In the prior art, the active layer of the LED is a quantum well structure, in which the barrier layer is usually doped with Al components to effectively limit the recombination and luminescence of carriers in the potential well layer. Usually, from the N-type semiconductor layer to the P-type semiconductor layer, the Al component content is evenly distributed or increases in the barrier layer of the active layer to reduce electron overflow. However, due to the difference in Al components between the electron blocking layer on the active layer and the P-type semiconductor layer side, the lattice constant mismatch between the semiconductor layers will cause stress concentration problems, resulting in a significant piezoelectric effect at the interface between the light-emitting layer and the electron blocking layer of the P-type semiconductor layer. The uneven distribution of carriers in the quantum well directly affects the radiation recombination process in the quantum well, reduces the photon generation efficiency, and leads to a decrease in the overall luminescence performance.

[0004] In the design and manufacturing process of LEDs, it is necessary to provide an improved technical solution for the above-mentioned deficiencies in the prior art to reduce or eliminate the piezoelectric effect and further improve the photoelectric conversion efficiency and / or luminous brightness of LED products. Summary of the invention

[0005] In view of the above defects and deficiencies in the prior art, the purpose of the present application is to provide a light emitting diode and a light emitting device to solve one or more of the above problems.

[0006] According to one aspect of the present application, a light emitting diode is provided, comprising a semiconductor stack, wherein the semiconductor stack comprises a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence; wherein:

[0007] The active layer is a quantum well structure having a plurality of pairs of alternately arranged barrier layers and well layers, wherein the barrier layers contain Al components; along the growth direction of the semiconductor stack, the average content of the Al component in at least part of the barrier layers is greater than the average content of the Al component in the next barrier layer adjacent thereto.

[0008] According to one aspect of the present application, the present application also provides a light emitting device, the light emitting device comprising:

[0009] Package substrate;

[0010] At least one light emitting diode is arranged on the surface of the packaging substrate, and the packaging substrate is electrically connected to the electrode structure of the light emitting diode; the light emitting diode is the light emitting diode described in the above technical solution.

[0011] Compared with the prior art, the light emitting diode and the light emitting device provided by the present application have at least the following beneficial effects:

[0012] In the technical solution of the present application, by regulating the change in the content of the Al component in the active layer, the average content of the Al component in at least part of the barrier layer is greater than the average content of the Al component in the next barrier layer adjacent thereto, so as to ensure that the average content of the Al component in the barrier layer in the active layer does not decrease continuously from the P side to the N side, so as to alleviate the drastic change of the conductive energy band close to the P side, avoid the formation of a two-dimensional electron gas-like binding of carriers, and holes can be smoothly injected in the valence band direction, and since the energy band piezoelectric field is alleviated, the hole distribution is more uniform; in addition, the electron overflow phenomenon in the quantum well layer is also effectively suppressed, and the carrier concentration and recombination efficiency in the active layer are significantly improved; in addition, the light-emitting device provided by the present application includes the light-emitting diode provided by the above technical solution, and therefore, the light-emitting device also has the above-mentioned good technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The positional relationships described in the drawings in the following description are based on the directions in which the components are drawn in the diagrams, unless otherwise specified.

[0014] For the purpose of convenience or clarity, the thickness and size of each layer shown in the drawings may be exaggerated, omitted or roughly drawn. In addition, the size of the light emitting diode does not completely reflect the actual size.

[0015] Figure 1 The figure shows the relationship between the Al component content and the depth in a part of the light emitting diode in the prior art;

[0016] Figure 2 Shown is a schematic cross-sectional structure diagram of a light emitting diode provided in one embodiment of the present application;

[0017] Figure 3 Shown is a schematic diagram of the cross-sectional structure of an active layer provided in one embodiment of the present application;

[0018] Figure 4A graph showing the relationship between the Al component content and the depth in a part of a light-emitting diode provided in an embodiment of the present application;

[0019] Figure 5 Shown is a schematic structural diagram of a light emitting device provided in one embodiment of the present application.

[0020] List of reference numerals:

[0021] 100 Substrate

[0022] 210 Buffer layer

[0023] 220 first semiconductor layer

[0024] 230 Stress relief layer

[0025] 300 Active layer

[0026] 310 Barrier layer

[0027] 320 Potential well layer

[0028] 410 Linking Layer

[0029] 420 Electron blocking layer

[0030] 430 hole supply layer

[0031] 440 Second semiconductor layer

[0032] 500 Insulation

[0033] 610 First Electrode

[0034] 620 Second Electrode

[0035] 10 Lighting device

[0036] 101 Package substrate

[0037] 102 Light-emitting element DETAILED DESCRIPTION

[0038] In the prior art, the active layer of LED is a quantum well structure, and its barrier layer usually has a higher band gap, so as to effectively limit the recombination of carriers in the potential well layer. Therefore, a certain amount of Al (such as AlGaN) is often added to the barrier layer to increase the band gap of the material. Figure 1As shown, the position of the highest peak of Al content on the left (the first Al peak on the left in the figure) is the P-type semiconductor electron blocking layer (P-EBL), which is usually doped with a large amount of Al components to suppress electron leakage and improve hole injection efficiency. There are 10 Al content peaks on the right, which are 10 quantum well layers, that is, 10 barrier layers. The horizontal axis represents the direction from the P-type layer to the N-type layer from left to right. According to this direction, the Al content of the barrier layers of different layers along the direction from the P-type layer to the N-type layer in the current quantum well structure is generally designed to be a gradient distribution from high to low, or the Al content of each barrier layer is controlled at a relatively close level to maintain the consistency of the product, that is, the Al component in the barrier layer closest to the N side must be the lowest Al component, and its Al component is too different from that of the P-type semiconductor electron blocking layer. The above design cannot alleviate the problem of stress concentration caused by lattice constant mismatch between semiconductor layers. There is a significant piezoelectric effect at the interface between the light-emitting layer and the electron blocking layer of the P-type semiconductor layer. The carrier distribution in the quantum well is uneven, which directly affects the radiation recombination process in the quantum well, reduces the efficiency of photon generation, and leads to a decrease in the overall luminescence performance.

[0039] Based on the background technology and the above technical defects, the present application provides a light-emitting diode, including a semiconductor stack, wherein the semiconductor stack includes a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence; wherein:

[0040] The active layer is a quantum well structure having a plurality of pairs of alternately arranged barrier layers and well layers, wherein the barrier layers contain Al components; along the growth direction of the semiconductor stack, i.e., the direction from the first semiconductor layer (N-type layer) to the second semiconductor layer (P-type layer), the average content of the Al component in at least part of the barrier layers is greater than the average content of the Al component in the next barrier layer adjacent thereto.

[0041] By adopting the above technical solution: in the direction from the first semiconductor layer to the second semiconductor layer, the average content of the Al component in at least part of the barrier layer is greater than the average content of the Al component in the next barrier layer adjacent to it, thereby avoiding the Al component of the barrier layers of different layers from constantly decreasing or remaining constant, so as to reduce the piezoelectric effect formed between the active layer and the electron blocking layer on the P side, so that the carriers can be more evenly distributed in the quantum well, thereby improving the carrier recombination efficiency.

[0042] In some embodiments, along the growth direction of the semiconductor stack, the average content of the Al component in each barrier layer is greater than the average content of the Al component in the next barrier layer adjacent thereto. From the barrier layer of the first pair of quantum well structures in the active layer to the last pair of barrier layers, the Al component has a gradient change, which optimizes the distribution of the Al component and further improves the piezoelectric effect.

[0043] In some embodiments, the active layer includes 2 to 20 quantum well structures arranged alternately in a periodic manner, and the material of the barrier layer includes Al x1 In y1 Ga 1-x1-y1 N, the material of the potential well layer includes Al x2 In y2 Ga 1-x2-y2 N, where 0≤x2<x1≤1, 0≤y1<y2≤1. By setting an appropriate number of quantum well periods to obtain a better threshold current, the quaternary material precisely controls the energy band gap of the barrier layer and the potential well layer, thereby optimizing the device's energy band structure and carrier transport characteristics.

[0044] In some embodiments, the Al component content at any point inside each barrier layer is 80% to 120% of the average Al component content of the barrier layer. The relatively uniform distribution of Al components in each layer helps to form a stable energy band structure, improve the distribution of carriers in the quantum well layer, and also helps to reduce lattice defects and impurities in the barrier layer, thereby improving the crystal growth quality of the active layer.

[0045] In some embodiments, along the growth direction of the semiconductor stack, the average Al component content difference of adjacent barrier layers is equal or unequal, that is, the Al component content of adjacent barrier layers may change uniformly or non-uniformly. Under the premise of maintaining the overall gradual change trend of the Al component in the active layer, the gradual change mode and degree of gradual change can be optimized according to demand to further improve the carrier distribution in the active layer.

[0046] In some embodiments, along the growth direction of the semiconductor stack, the barrier layer has a relative lower surface and upper surface, and from the lower surface to the upper surface, each barrier layer has an initial content and an end content of an Al component; wherein the end content is less than the initial content, and the end content of each barrier layer is greater than or equal to the initial content of the next barrier layer adjacent thereto. This helps to form a smooth energy band transition between adjacent layers, reduce the energy band discontinuity at the interface, thereby reducing the scattering and recombination loss of carriers at the interface, and reduce the lattice stress accumulation caused by the sudden change of the Al component, thereby improving the long-term stability and reliability of the device.

[0047] In some embodiments, the Al component content in the barrier layer of the active layer is between 30% and 0%.

[0048] In some embodiments, the Al component content in the barrier layer of the active layer is between 5×10 19 atom / cm 3 ~ 0. This component content range can provide a certain band gap width without excessively affecting the carrier mobility and device reliability.

[0049] In some embodiments, the thickness of the barrier layer is between The appropriate thickness can form a sufficient barrier height to prevent carriers from leaking from the quantum well layer to the barrier layer or other regions, and avoid stress concentration problems between or within layers.

[0050] In some embodiments, the thickness of each barrier layer is equal or different. For different types of semiconductor devices, the thickness of certain barrier layers can be adjusted separately to obtain better product performance.

[0051] In some embodiments, a stress release layer is further included, and the stress release layer is located between the first semiconductor layer and the active layer.

[0052] In some embodiments, an electron blocking layer is further included, and the electron blocking layer is located between the active layer and the second semiconductor layer. By limiting the flow of electrons from the active layer to the P-type semiconductor layer, electron overflow is reduced, thereby improving carrier recombination efficiency.

[0053] In the above embodiment, a connection layer is further included, and the connection layer is located between the active layer and the electron blocking layer.

[0054] In some embodiments, the semiconductor stack has a first mesa exposing the first semiconductor layer, and the semiconductor stack adjacent to the first mesa forms a light emitting mesa, further comprising:

[0055] An insulating layer, located above and on the sidewalls of the semiconductor stack, the insulating layer having through holes penetrating the light emitting mesa of the first semiconductor layer and the first mesa of the second semiconductor layer respectively;

[0056] The pad electrode includes a first electrode and a second electrode, which are located on the insulating layer and fill the through holes respectively, wherein the first electrode forms an electrical contact with the first semiconductor layer, and the second electrode forms an electrical contact with the second semiconductor layer.

[0057] In some embodiments, the wavelength of the light radiated by the light emitting diode is between 400 nm and 760 nm. The above technical solution is particularly suitable for white light and blue-green light emitting diodes.

[0058] The present application also provides a light-emitting device, the light-emitting device comprising:

[0059] Package substrate;

[0060] At least one light emitting diode is disposed on the surface of the packaging substrate, and the packaging substrate is electrically connected to the electrode structure of the light emitting diode; the light emitting diode is the light emitting diode described in any one of the above technical solutions. The light emitting device includes the above light emitting diode, so it also has good photoelectric conversion efficiency and light brightness.

[0061] The composition and dopant of each layer included in the light-emitting diode of the present application can be analyzed by any suitable method, such as secondary ion mass spectrometer (SIMS). The thickness of each layer included in the light-emitting diode of the present application can be analyzed by any suitable method, such as transmission electron microscopy (TEM) or scanning electron microscopy (SEM), for example, to match the depth position of each layer on the SIMS map.

[0062] The following specific embodiments illustrate the implementation of the present application, and those familiar with the technology can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0063] For ease of description, the growth direction of the semiconductor stack is defined as upward, and the opposite direction is defined as downward, that is, the growth direction of the semiconductor stack is from the first semiconductor layer (ie, N-type layer) to the second semiconductor layer (P-type layer).

[0064] like Figure 2-3 As shown, this embodiment provides a light emitting diode, which includes a semiconductor stack formed on a substrate 100, and the semiconductor stack includes at least a first semiconductor layer 220, an active layer 300 and a second semiconductor layer 440 stacked in sequence.

[0065] The substrate 100 is a transparent substrate, including a sapphire substrate, a silicon carbide substrate, a silicon substrate, a gallium nitride substrate or an aluminum nitride substrate, etc., with a thickness ranging from 500 μm to 2000 μm. As an example, the substrate 100 is a sapphire substrate, which helps to improve the light efficiency and luminous intensity of blue-green light or white light LEDs. In some embodiments, the substrate 100 can also be a patterned sapphire substrate.

[0066] Continue to see Figure 2-3The N-side semiconductor layer can be set to a multilayer structure composed of nitride semiconductors such as GaN, InGaN, and AlGaN. The N-side semiconductor layer includes a buffer layer 210, a first semiconductor layer 220, and a stress release layer 230 stacked in sequence on the substrate 100. According to requirements, the N-side semiconductor layer can also be configured with other layers in addition to the above layers, and in addition, some layers can also be omitted.

[0067] In some embodiments, a buffer layer 210 is formed on the substrate 100, and the buffer layer 210 is located between the substrate 100 and the first semiconductor layer 220. The buffer layer 210 is an n-type material layer made of a GaN-based III-V nitride semiconductor, or an undoped material layer, such as an unintentionally doped GaN layer (undropped GaN, u-GaN), which is used to relieve stress caused by lattice constant mismatch between the substrate 100 and the first semiconductor layer 220, and can also optimize the process so that the semiconductor stack is better formed on the substrate 100.

[0068] In some embodiments, a first semiconductor layer 220 is formed on the buffer layer 210 as an N-type semiconductor layer to provide electrons. The N-type doped nitride layer in the first semiconductor layer 220 may include one or more N-type impurities of group IV elements. The N-type impurities may include one or a combination of Si, Ge, Sn.

[0069] In some embodiments, a stress release layer 230 is formed on the first semiconductor layer 220. The stress release layer 230 is located between the first semiconductor layer 220 and the active layer 300 and has a thickness between 1000 and 2000. The stress release layer 230 contains an In component, such as InGaN, to reduce lattice defects caused by lattice constant mismatch, effectively transfer the lattice constant from the first semiconductor layer 220 to the InGaN quantum well layer in the active layer 300, improve the interface flatness of the active layer 300, reduce the generation of V-pits, and provide a better growth environment for the quantum well layer, thereby improving the crystal quality of the active layer 300.

[0070] In some embodiments, an active layer 300 is formed on the stress release layer 230. The active layer 300 is a quantum well structure having a plurality of pairs of alternately arranged barrier layers 310 and well layers 320. The barrier layer 310 contains an Al component. The material of the barrier layer includes Al x1 In y1 Ga 1-x1-y1 N, the material of the potential well layer includes Al x2 In y2 Ga 1-x2-y2N, where 0≤x2<x1≤1, 0≤y1<y2≤1, by setting an appropriate number of quantum well periods to obtain a better threshold current, the quaternary material accurately controls the energy band gap of the barrier layer and the well layer, thereby optimizing the energy band structure and carrier transport characteristics of the device. The barrier layer 310 can be a nitride semiconductor with a lower In content than the well layer 320 but a higher Al content than the well layer 320, such as AlInGaN or AlGaN. If the well layer 320 and the barrier layer 310 are alternately stacked, the first and last layers can be either well layers or barrier layers.

[0071] Along the growth direction of the semiconductor stack, the average Al content in at least part of the barrier layer 310 is greater than the average Al content in the next barrier layer 310 adjacent thereto. That is, for the active layer 300 having two pairs of quantum well structures, the Al content of the barrier layer 310 close to the N side is greater than the Al content of the barrier layer 310 close to the P side, so that the Al content in the barrier layer 310 close to the P side semiconductor layer is lower than the Al content of the layer in the existing product, so as to reduce the composition difference between the active layer 300 and the P side electron blocking layer 420, reduce the piezoelectric effect between the active layer 300 and the electron blocking layer 420, and improve the product performance stability. For a quantum well structure having more than two pairs, the Al component of part of the barrier layer 310 can be selectively set to a gradient distribution from high to low.

[0072] Table 1 is a barrier layer Al component distribution design provided by this embodiment. From bottom to top, the barrier layers 310 are defined as the first barrier layer, the second barrier layer...the kth barrier layer, and correspondingly, the potential well layer 320 is defined as the first well layer, the second well layer...the jth well layer, k>2 and an integer, j>2 and an integer. As an example, the active layer of the product provided by this embodiment has 10 pairs of quantum wells, that is, ten barrier layers, and the Al component content in the barrier layers is between 20% and 30%. The Al component in the first five barrier layers is uniformly distributed, and the Al component content in the first barrier layer to the fifth barrier layer is 30%, and the Al doping concentration is 5×10 19 atom / cm 3 The Al content in the sixth to tenth barrier layers is 20%, and the Al doping concentration is 3.3×10 19 atom / cm 3 , the Al content in the last five barrier layers is evenly distributed and lower than that in the first five barrier layers. Compared with the high Al content in the first five layers, the Al content in the last five layers close to the P-type semiconductor layer, especially the last barrier layer, is reduced, which reduces the composition difference between this layer and the P-side electron blocking layer 420, and the interlayer piezoelectric effect is correspondingly reduced, thereby improving product stability.

[0073] Table 1 Al component content and doping concentration parameters of the barrier layer in sample 1

[0074] Barrier layer number Al component content (%) Al doping concentration (E19) 1 30 5 2 30 5 3 30 5 4 30 5 5 30 5 6 20 3.3 7 20 3.3 8 20 3.3 9 20 3.3 10 20 3.3

[0075] In an optional embodiment, the Al component content of the first barrier layer close to the N-side semiconductor layer is the layer with the highest Al component content of all barrier layers 310 in the active layer 300, and the Al component content decreases from the second barrier layer to the i-th barrier layer, i<k, and the Al component content from the i+1-th barrier layer to the k-th barrier layer remains unchanged. In an optional embodiment, the Al component content of several barrier layers close to the N-side semiconductor layer is the same and they are all the layers with the highest Al component content of all barrier layers 310 in the active layer 300, and the Al content decreases from a certain barrier layer to the k-th barrier layer.

[0076] In an optional embodiment, certain barrier layers are arranged in groups with a decreasing content in one group or a constant content in another group, so as to achieve a decreasing trend of the overall Al content of the active layer 300 from high to low, and ensure that the Al content of the last barrier layer close to the P-side semiconductor layer is the lowest value of the barrier layer 310 in the active layer 300.

[0077] In an optional embodiment, the Al component content at any point inside each barrier layer 310 is 80% to 120% of the average Al component content in the barrier layer 310, and a relatively constant Al component content is maintained to form a relatively stable energy band structure and reduce crystal defects in the active layer 300. In an optional embodiment, the specific difference in the Al content inside each barrier layer 310 is not limited to a gradual trend from high to low, and can also be in the form of from low to high, from high to low, or multiple doping peaks or irregular component distribution, as long as the Al component content at any point inside each barrier layer 310 is 80% to 120% of the average Al component content in the barrier layer 310, which will not be elaborated here.

[0078] In some embodiments, along the growth direction of the semiconductor stack, the average content of the Al component in each barrier layer is greater than the average content of the Al component in the next barrier layer adjacent thereto. That is, the Al content in the barrier layer of the active layer is designed to have a gradually decreasing trend from the N side to the P side, with the lowest Al content in the barrier layer close to the P side semiconductor layer and gradually increasing close to the N side, so as to alleviate the drastic change of the conductive energy band close to the P side, avoid the formation of a two-dimensional electron gas-like binding of carriers, and in the valence band direction, holes can be smoothly injected, and because the energy band piezoelectric field is alleviated, the hole distribution is also more uniform.

[0079] In some embodiments, along the growth direction of the semiconductor stack, the average content difference of the Al component of adjacent barrier layers 310 is equal or unequal. Under the premise of maintaining the overall gradual change trend of the Al component of the barrier layer 310 in the active layer 300, the gradual change mode and degree of gradual change are optimized to further improve the carrier distribution in the active layer. That is, the Al content gradual change trend of the barrier layer 310 in the active layer 300 can be arithmetic or non-arithmetic, for example, the difference in Al content in several barrier layers 310 close to the N-side or P-side semiconductor layer can be lower than the difference in Al content in several barrier layers 310 in the middle of the active layer 300. When the Al content in adjacent barrier layers is designed to be arithmetic and gradual from high to low, the Al content of the i-th barrier layer is [xx(i-1) / (k-1)]%, x is the maximum value of the Al content, and k is the number of periods of the barrier layer 310.

[0080] Along the growth direction of the semiconductor stack, the barrier layer 310 has a relative lower surface and upper surface. From the lower surface to the upper surface, each barrier layer 310 has an initial content and an ending content of an Al component, and the ending content of each barrier layer 310 is greater than or equal to the initial content of the next barrier layer 310 adjacent to it. The above component distribution helps to form a smooth energy band transition between adjacent layers, reduce the energy band discontinuity at the interface, thereby reducing the scattering and recombination losses of carriers at the interface, and reduce the lattice stress accumulation caused by the sudden change of the Al component, thereby improving the long-term stability and reliability of the device.

[0081] In some embodiments, the active layer 300 includes a quantum well structure with 2 to 20 periods arranged alternately, and the maximum value of the Al component content in the barrier layer 310 is 30%, that is, the maximum starting content is 30%, and the minimum value is 0, that is, the minimum ending content is 0. As an example, the starting content and the ending content of the barrier layer 310 can be 30% and 5%, or 25% and 5%, or 25% and 10%, or 20% and 10%, or 15% and 10%, etc. It can be understood that when the starting content of the barrier layer 310 is lower than 20%, its ending content should not be too low to avoid the situation where the barrier height is insufficient and the carrier leakage cannot be effectively blocked, thereby reducing the internal quantum efficiency of the LED. For example, the ending content of the barrier layer 310 can be in the range of 5% to 15%, so as to ensure that the total amount of Al element in the active layer 300 is appropriate. It can be understood that when the initial content of the barrier layer 310 is higher than 20%, its termination content can be reduced accordingly until the last barrier layer is not doped with Al components, so as to reduce the interlayer lattice mismatch and stress concentration, or reduce the defect or impurity concentration, thereby avoiding the problem of causing the crystal quality to deteriorate. For example, the termination content of the barrier layer 310 can be in the range of 0 to 15%.

[0082] In an optional embodiment, the Al component content in the barrier layer 310 is between 30% and 0%, and the Al content between adjacent barrier layers 310 is arithmetic decreasing, that is, uniform change. As an example, the Al content of the first barrier layer is 30% and the Al content of the kth barrier layer is 0 (k=20), and the Al content in the adjacent barrier layers is designed to be arithmetic gradient from high to low, the Al content of the second barrier layer is [30-30 / (20-1)]2%=28.4%, the Al content of the third barrier layer is 26.8%, and so on, until the Al content of the last barrier layer is reduced to 0.

[0083] Table 2 shows a barrier layer Al component distribution design provided in this embodiment. It can be seen that the active layer of the product provided in the table below has 10 pairs of quantum wells, including 10 barrier layers, the Al component content in the barrier layer is between 3% and 30%, and the doping concentration is between 0.5×10 19 atom / cm 3 ~5×10 19 atom / cm 3 The Al content of the first barrier layer is 30%, and the Al doping concentration is 5×10 19 atom / cm 3 The Al content decreases evenly from the first barrier layer, so that the carriers can be more evenly distributed in the quantum well, until the Al content of the tenth barrier layer is reduced to 3%, and the Al doping concentration is reduced to 0.5×10 19 atom / cm 3 The uniformly decreasing Al component distribution of the barrier layer can alleviate the drastic change of the conductive energy band near the P-type semiconductor layer, avoid the formation of a two-dimensional electron gas to bind the carriers, and allow holes to be smoothly injected into the active layer and recombine with electrons. In addition, since the energy band piezoelectric field is alleviated, the hole distribution is also more uniform.

[0084] Table 2 Al component content and doping concentration parameters of the barrier layer in sample 2

[0085] Barrier layer number Al component content (%) Al doping concentration (E19) 1 30 5 2 27 4.5 3 24 4 4 21 3.5 5 18 3 6 15 2.5 7 12 2 8 9 1.5 9 6 1 10 3 0.5

[0086] In an optional embodiment, the Al component content in the barrier layer 310 is between 30% and 0%, and the Al component content in the barrier layer 310 shows a non-equilibrium decreasing trend. As an example, the Al content range of the first barrier layer can be any parameter in [30%, 25%], the Al content range of the second barrier layer can be any parameter in [25%, 20%]... The Al content range of the last barrier layer can be any parameter in [5%, 0%], so that the active layer 300 as a whole shows a trend of Al content variation from high to low. Furthermore, the Al component content in different barrier layers 310 is adjusted according to the thickness of the layer, and the thickness of the barrier layer 310 is between A relatively thicker barrier layer 310 may have a lower Al content parameter, and a relatively thinner barrier layer 310 may have a higher Al content parameter, so as to meet the bandgap width requirement and play an effective blocking role.

[0087] Table 3 shows a barrier layer Al component distribution design provided in this embodiment. It can be seen that the active layer of the product provided in the table below has 10 barrier layers, the Al component content in the barrier layer is between 0% and 30%, and the doping concentration is between 0% and 5×10 19 atom / cm 3 The Al content of the first barrier layer is 30%, and the Al doping concentration is 5×10 19 atom / cm 3 , the Al content decreases non-uniformly from the first barrier layer until the Al content of the tenth barrier layer decreases to 0. After testing, sample 3 with non-uniform decrease of Al content in the barrier layer also has better photoelectric performance, and the luminous brightness is significantly improved compared with the existing products.

[0088] Table 3 Al component content and doping concentration parameters of the barrier layer in sample 3

[0089] Barrier layer number Al component content (%) Al doping concentration (E19) 1 30 5 2 25 4.17 3 22 3.67 4 18 3 5 17 2.83 6 15 2.5 7 12 2 8 9 1.5 9 5 0.83 10 0 0

[0090] Furthermore, the active layer 300 includes 4 to 16 quantum well structures arranged alternately in periods. As an example, the number of periods of the quantum well structure of the active layer can be 6, 8, 10, 12 or 14. Quantum well layer designs with different structures are selected according to different device performance requirements. Figure 4 The ion concentration curve of the quantum well structure with 10 alternating periods is shown. The first peak on the left is the P-type electron blocking layer. The S1 segment is the thickness region where the active layer 300 is located, and its Al content is between 5×10 18 atom / cm 3 ~1×10 19 atom / cm 3 The Al content in each adjacent barrier layer 310 decreases almost in an arithmetic progression. Compared with the control samples with the same average Al content, after testing, Figure 4 The luminous efficiency of the product shown is increased from 1.752 to 1.841, the brightness is increased by 5.08%, and the operating voltage remains the same.

[0091] In an optional embodiment, the Al component content in the barrier layer 310 is between 5×10 19 atom / cm 3 ~0. This corresponds to the content parameter that the Al component content in the barrier layer 310 is between 30% and 0%, which will not be described in detail here.

[0092] In an optional embodiment, the thickness of each barrier layer in the active layer 300 may be the same or different, and the thickness of each well layer may be the same or different. For different types of semiconductor devices, the thickness of certain barrier layers 310 may be adjusted separately to obtain better product performance. According to the thickness difference of different barrier layers 310 and well layers 320, the Al component content in the corresponding layer is adjusted to achieve better carrier recombination efficiency and light output brightness.

[0093] It can be understood that in the active layer 300 of the multi-quantum well structure, the barrier layer in the two well layers is not particularly limited to one layer (well layer / barrier layer / well layer), and two or more barrier layers can be arranged in the form of well layer / barrier layer a / barrier layer b / … / well layer, and multiple barrier layers with different composition and impurity content can be arranged. For the design of the continuous barrier layer, the Al content design scheme in the above embodiment is still followed, so that the Al components in the contacting continuous barrier layers are respectively arranged to decrease from high to low. See Figure 4 In this embodiment, the number of well layers is set to 10, and the number of barrier layers is set to 10, but it is not limited thereto. For example, the number of well layers may be increased to 12 layers or reduced to a smaller number such as 8 layers instead of 10 layers; the number of barrier layers may be increased to 16 layers or reduced to a smaller number such as 4 layers instead of 10 layers.

[0094] In some embodiments, along the growth direction of the semiconductor stack, the average content of the Al component in each barrier layer 310 is greater than the average content of the Al component in the next barrier layer 310 adjacent thereto. That is, under the premise that the Al component inside each barrier layer 310 remains constant, in order to make the active layer 300 present a decreasing trend of the overall Al content, the Al content of any point in the i-th barrier layer is greater than or equal to the Al content in the i+1-th barrier layer. The uniformly distributed Al component in each layer helps to form a stable energy band structure, improves the distribution of carriers in the quantum well layer, and also helps to reduce lattice defects and impurities in the barrier layer 310, thereby improving the overall crystal growth quality of the active layer 300.

[0095] Along the growth direction of the semiconductor stack, the barrier layer 310 has a relative lower surface and an upper surface, and from the lower surface to the upper surface, each barrier layer 310 has an initial content and an ending content of an Al component; wherein the ending content of each layer is less than the initial content of the layer, that is, the Al component content inside each barrier layer 310 also maintains a decreasing trend from high to low, and the ending content of each barrier layer 310 is greater than or equal to the starting content of the next barrier layer 310 adjacent to it. Compared with the gradient decreasing distribution of the Al component between layers, the above technical solution can form a smoother energy band transition, reduce the energy band discontinuity at the interface, thereby reducing the scattering and recombination loss of carriers at the interface, and reduce the lattice stress accumulation caused by the sudden change of the Al component, thereby improving the long-term stability and reliability of the device. As an example, for a quantum well structure with 20 periods, the Al component content in the barrier layer 310 is between 30% and 0%, and the Al component between adjacent barrier layers 310 and inside each barrier layer 310 changes uniformly. The Al content of the first barrier layer gradually decreases from 30% to 28.4%, and the Al content of the second barrier layer gradually decreases from 28.4% to 26.8%, and so on, until the Al content of the last barrier layer is reduced to 0.

[0096] Table 4 shows the Al component distribution design of the first barrier layer of a barrier layer provided in this embodiment. The thickness of the first barrier layer of this sample is The initial Al content of the first barrier layer is 30%, and the doping concentration is 5×10 19 atom / cm 3 The Al component termination content of the first barrier layer is 25%, and the doping concentration is 4.17×10 19 atom / cm 3 . Inside the first barrier layer, the Al component is distributed in a decreasing manner from bottom to top. The initial Al component content of the second barrier layer is less than or equal to 25%, and there is a concentration gradient inside each barrier layer from the second barrier layer to the last barrier layer, forming a smoother energy band transition, thereby improving the long-term stability and reliability of the device.

[0097] Table 4 Al component content and doping concentration parameters of the first barrier layer of the barrier layer in sample 4

[0098] depth Al component content (%) Al doping concentration (E19) 0 30 5 10 29 4.83 20 28 4.67 30 27 4.5 40 26 4.33 50 25 4.17

[0099] In the above embodiment, the thicknesses of different barrier layers 310 may be the same or different, for example, Or set it to other thickness as required. or In an optional embodiment, the thickness of the barrier layer 310 close to the N-side semiconductor layer is smaller to enable effective electron injection. For barrier layers 310 of different thicknesses, the rate of change of the Al component content in the layer is also different, but the range of change of the Al component content in the layer, that is, the difference in the Al content in the layer remains the same. In an optional embodiment, in order to ensure the continuity of the energy band at the interface and the crystal quality at the interface, for barrier layers 310 of different thicknesses, the rate of change of the Al component content in the layer remains the same, and the change in element content changes arithmetic with the change in thickness. Although the difference between the initial content and the final content of the Al component of barrier layers 310 of different thicknesses is different, the composition and structural stability of the barrier layer 310 can be improved.

[0100] In some embodiments, the thickness of the barrier layer 310 is between The appropriate thickness can form a sufficient barrier height to prevent carriers from leaking from the quantum well layer to other areas, and avoid interlayer or intralayer stress concentration problems. In an optional embodiment, the thickness of each barrier layer 310 is the same to optimize the process. In an optional embodiment, the thickness of each barrier layer 310 may also be partially different. For example, the barrier layer 310 close to the N-side semiconductor layer is relatively thinner, and several barrier layers located in the middle of the active layer 300 have the same thickness. The barrier layer 310 located close to the P-side semiconductor is relatively thicker. For the thinner barrier layer 310, the variation of the Al component content within the layer should be relatively small or set to be uniformly distributed to reduce the process difficulty and improve the distribution accuracy of the Al component. It can be understood that the thickness design of the barrier layer 310 at different positions can be individually designed according to actual needs, and the variation of the Al component content is also individually designed according to the actual thickness, which is not listed here. Furthermore, the thickness of the barrier layer 310 is between between.

[0101] In some embodiments, a P-side semiconductor layer is formed on the active layer 300, and can be formed as a single layer or a multilayer structure formed of a nitride semiconductor layer containing p-type impurities such as Mg, Zn, and Be. The P-side semiconductor layer includes a connecting layer 410, an electron blocking layer 420, a hole supply layer 430, and a second semiconductor layer 440 stacked in sequence. The P-side semiconductor layer can also be configured with other layers in addition to the above layers, and a part of the layers can also be omitted.

[0102] In some embodiments, a connecting layer 410 is first formed on the active layer 300. The connecting layer 410 is located between the active layer 300 and the electron blocking layer 420. The material of the connecting layer 410 is AlGaN or GaN, so that the P-side semiconductor layer can be well grown on the active layer 300, reducing the structural and quality defects caused by the interlayer lattice mismatch. By adjusting the doping elements and doping concentrations, the band structure can also be adjusted to better achieve energy level matching, thereby improving the carrier recombination efficiency and luminescence performance.

[0103] In some implementations, an electron blocking layer 420 is first formed on the connection layer 410 to confine electrons within the active layer 300 to prevent electron overflow, and the electron blocking layer 420 may be composed of P-type doped AlGaN.

[0104] In some embodiments, a hole supply layer 430 and a second semiconductor layer 440 are formed on the electron blocking layer 420. The hole supply layer 430 is used to inject holes into the active layer 300, reduce the recombination loss of electrons and holes during the transmission process, and improve the carrier recombination efficiency. The Al component content of the hole supply layer 430 is lower than the average Al component content of the barrier layer 310, and the second semiconductor layer 440 can be p-GaN.

[0105] The light emitting diode provided in the present application further includes an electrode structure. Specifically, the semiconductor stack has a first mesa exposing the N-side semiconductor layer, and the semiconductor stack adjacent to the first mesa forms a light emitting mesa, and further includes:

[0106] An insulating layer 500, located above and on the sidewalls of the semiconductor stack, the insulating layer 500 having through holes penetrating to the first mesa of the N-side semiconductor layer and the light-emitting mesa of the P-side semiconductor layer respectively;

[0107] The pad electrode, including a first electrode 610 and a second electrode 620 , is located on the insulating layer 500 and fills the through holes respectively. The first electrode 610 forms an electrical contact with the first semiconductor layer 220 , and the second electrode 620 forms an electrical contact with the second semiconductor layer 440 .

[0108] The wavelength of the radiated light of the light emitting diode provided in this embodiment is between 400nm and 760nm, and is particularly suitable for white light and blue-green light light emitting diodes.

[0109] This embodiment also provides a light emitting device 10, see Figure 5 The light emitting device 10 includes a package substrate 101; at least one light emitting diode is disposed on the surface of the package substrate 101, and the package substrate 101 is electrically connected to the electrode structure of the light emitting diode. The light emitting element 102 can be the light emitting diode provided in the above embodiment of the present application, and the light emitting diode is electrically connected to the package substrate 101 through the first electrode 610 and the second electrode 620. Therefore, the light emitting device 10 has good luminous brightness and good quality reliability as the light emitting diode.

[0110] In summary, the light emitting diode and the light emitting device provided by the present application effectively overcome various shortcomings in the prior art and have high industrial utilization value.

[0111] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A light emitting diode, characterized in that: The method comprises a semiconductor stack, wherein the semiconductor stack comprises a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence; wherein: The active layer is a quantum well structure having a plurality of pairs of alternately arranged barrier layers and well layers, wherein the barrier layers contain Al components; along the growth direction of the semiconductor stack, the average content of the Al component in at least part of the barrier layers is greater than the average content of the Al component in the next barrier layer adjacent thereto.

2. The light emitting diode according to claim 1, characterized in that: Along the growth direction of the semiconductor stack, the average content of Al components in each barrier layer is greater than the average content of Al components in the next barrier layer adjacent thereto.

3. The light emitting diode according to claim 1, characterized in that: The active layer includes 2 to 20 quantum well structures arranged alternately in cycles, and the material of the barrier layer includes Al x1 In y1 Ga 1-x1-y1 N, the material of the potential well layer includes Al x2 In y2 Ga 1-x2-y2 N, where 0≤x2<x1≤1, 0≤y1<y2≤1.

4. The light emitting diode according to claim 1, characterized in that: The Al component content at any location inside each barrier layer is 80% to 120% of the average Al component content of the barrier layer.

5. The light emitting diode according to claim 1, characterized in that: Along the growth direction of the semiconductor stack, the average Al component content differences of adjacent barrier layers are equal or different.

6. The light emitting diode according to claim 1, characterized in that: Along the growth direction of the semiconductor stack, the barrier layer has a relative lower surface and upper surface, and from the lower surface to the upper surface, each barrier layer has an initial content and an ending content of an Al component; wherein the ending content is less than the initial content, and the ending content of each barrier layer is greater than or equal to the starting content of the next barrier layer adjacent to it.

7. The light emitting diode according to claim 1, characterized in that: The Al component content in the barrier layer of the active layer is between 30% and 0%.

8. The light emitting diode according to claim 1, characterized in that: The Al content of the barrier layer of the active layer is between 5×10 19 atom / cm 3 ~0.

9. The light emitting diode according to claim 1, characterized in that: The thickness of the barrier layer is between between.

10. The light emitting diode according to claim 1, characterized in that: The thickness of each barrier layer is equal or different.

11. The light emitting diode according to claim 1, characterized in that: A stress release layer is also included, and the stress release layer is located between the first semiconductor layer and the active layer.

12. The light emitting diode according to claim 1, characterized in that: An electron blocking layer is also included, and the electron blocking layer is located between the active layer and the second semiconductor layer.

13. The light emitting diode according to claim 12, characterized in that: The invention also comprises a connecting layer, wherein the connecting layer is located between the active layer and the electron blocking layer.

14. The light emitting diode according to claim 1, characterized in that: The semiconductor stack has a first mesa exposing the first semiconductor layer, and the semiconductor stack adjacent to the first mesa forms a light emitting mesa, and further includes: An insulating layer, located above and on the sidewalls of the semiconductor stack, the insulating layer having through holes penetrating to the first mesa of the first semiconductor layer and the light-emitting mesa of the second semiconductor layer respectively; The pad electrode includes a first electrode and a second electrode, which are located on the insulating layer and fill the through holes respectively, wherein the first electrode forms an electrical contact with the first semiconductor layer, and the second electrode forms an electrical contact with the second semiconductor layer.

15. A light emitting device, characterized in that: The light emitting device comprises: Package substrate; At least one light emitting diode is disposed on the surface of the packaging substrate, and the packaging substrate is electrically connected to the electrode structure of the light emitting diode; the light emitting diode is the light emitting diode according to any one of claims 1 to 14.

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