Semiconductor light-emitting element and light-emitting device

Abstract

A semiconductor light-emitting element and a light-emitting device, where the semiconductor light-emitting element includes a semiconductor stack including an N-type semiconductor layer (120), a light-emitting layer (130) and a P-type semiconductor layer (140) stacked in sequence, where at least a portion of the N-type semiconductor layer contains n-type impurities having a concentration curve along a thickness direction, the concentration curve includes a first segment (L1) having a first concentration greater than 5 * 1018 atom / cm3 corresponding to a region of the N-type semiconductor layer (120) away from the light emitting layer (130), a second segment (L2) having a second concentration less than 1 * 1018 atom / cm3 corresponding to a region of the N-type semiconductor layer (120) close to the light emitting layer (130), and a third segment (L3) having a second concentration greater than 1 * 1018 atom / cm3 corresponding to a region of the N-type semiconductor layer (120) close to the light emitting layer (130). The second segment (L2) connects the first segment (L1) and the third segment (L3) and reduces the concentration of the n-type impurity from the first concentration to the second concentration, wherein the thickness of the third segment (L3) distributed in the semiconductor stack is greater than or equal to 10 nm. The semiconductor light-emitting element can effectively improve the photoelectric performance.

Description

Semiconductor light-emitting element and light-emitting device Technical Field

[0001] The present invention relates to the technical field of semiconductor devices and apparatuses, and in particular to a semiconductor light-emitting element and a light-emitting apparatus. Background Art

[0002] Semiconductor light-emitting elements are inorganic semiconductor devices that emit light through the recombination of electrons and holes. Ultraviolet (UV) light-emitting elements have broad application prospects in areas such as sterilization, polymer curing, biochemical detection, non-line-of-sight communications, and specialty lighting.

[0003] Ultraviolet light-emitting devices often use AlGaN as the barrier layer for quantum wells, limiting the Al content in the layer. This increases the Al content in the device. For both n-type and p-type doped AlGaN materials, this increase in average Al content leads to decreased crystal quality and increased defect density. This manifests itself in increased leakage current in the device, leading to malfunctions. Technical Solutions

[0004] An object of the present invention is to provide a semiconductor light emitting element and a light emitting device, which can suppress the leakage problem of the light emitting element.

[0005] According to a first aspect of the present invention, a semiconductor light-emitting element is provided, comprising a semiconductor stack, the semiconductor stack comprising an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer stacked in sequence, wherein the N-type semiconductor layer has a first surface and a second surface opposite to each other, the second surface being adjacent to the light-emitting layer. Furthermore, at least a portion of the N-type semiconductor layer contains n-type impurities, the n-type impurities having a concentration profile along the thickness of the semiconductor stack, the concentration profile comprising a first segment, a second segment, and a third segment, wherein the first segment corresponds to a region of the N-type semiconductor layer away from the light-emitting layer, and has a concentration greater than or equal to 5×10 18 atom / cm 3 The first concentration, the third section corresponds to the region of the N-type semiconductor layer close to the light emitting layer, with a concentration of less than 1×10 18 atom / cm 3 The second segment connects the first segment and the third segment, and reduces the concentration of the n-type impurity from the first concentration to the second concentration, wherein the thickness of the three segments distributed in the semiconductor stack is greater than or equal to 10 nm.

[0006] According to a second aspect of the present invention, a semiconductor light emitting element is provided, comprising a semiconductor stack, wherein the semiconductor stack comprises an N-type semiconductor layer, a light emitting layer, and a P-type semiconductor layer stacked in sequence, wherein the N-type semiconductor layer has a first surface and a second surface opposite to each other, wherein the second surface is close to the light emitting layer, and the N-type semiconductor layer comprises a first layer, a second layer, and a third layer, wherein the first layer is Al x1 Ga 1-x1 N semiconductor layer, with a value greater than 5×10 18 atom / cm 3 The first n-type doping concentration is 1, and the third layer is composed of Al x3 Ga 1-x3 N superlattice structure, the third layer is adjacent to the light-emitting layer, and the portion close to the light-emitting layer has a thickness of less than 1×10 18 atom / cm 3 The second n-type doping concentration of the portion is greater than or equal to 10 nm, and the second layer is Al x2 Ga 1-x2 The N semiconductor layer is located between the first layer and the second layer, and has an n-type doping concentration that is less than the first n-type doping concentration and greater than the second n-type doping concentration.

[0007] According to a third aspect of the present invention, a semiconductor light-emitting element is provided, comprising a semiconductor stack, wherein the semiconductor stack comprises an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer stacked in sequence, wherein the emission wavelength of the light-emitting layer is 340 to 425 nm, and the semiconductor stack has an n-type impurity concentration profile that varies along the thickness direction of the semiconductor stack, wherein the n-type impurity concentration profile has a value of less than or equal to 5×10 16 atom / cm 3 The concentration of the semiconductor stack is greater than or equal to 50 nm and less than 300 nm.

[0008] In a fourth aspect of the present application, a light-emitting device is provided, which includes a substrate and a semiconductor light-emitting element mounted on the substrate, and the light-emitting element can be any one of the aforementioned ones. Beneficial effects

[0009] Other features and benefits of the present invention will be described in the following description and, in part, will become apparent from the description or be understood through practice of the present invention. The objectives and other benefits of the present invention can be achieved and obtained through the structures specifically pointed out in the description, claims, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction will be given below 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work. The positional relationships described in the drawings in the following description are based on the directions of the components drawn in the diagrams, unless otherwise specified.

[0011] 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 device does not completely reflect the actual size.

[0012] FIG1 is a schematic cross-sectional view showing a light emitting element according to a first embodiment of the present invention.

[0013] FIG. 2 is a graph showing the relationship between the concentration or ion intensity of elements and the depth in a partial range of the semiconductor light emitting element according to the first embodiment of the present invention.

[0014] FIG3 is a schematic cross-sectional view showing a partial structure of a semiconductor light emitting element according to a first embodiment of the present invention.

[0015] FIG4 is a schematic cross-sectional view showing a light emitting element according to a second embodiment of the present invention.

[0016] FIG. 5 is a graph showing the relationship between the concentration or ion intensity of an element and the depth in a partial range of a semiconductor light emitting element according to the third embodiment of the present invention.

[0017] FIG. 6 is a graph showing the relationship between the concentration or ion intensity of an element and the depth in a partial range of the semiconductor light emitting element according to the fourth embodiment of the present invention.

[0018] FIG. 7 is a graph showing the relationship between the concentration or ion intensity of an element and the depth in a partial range of the semiconductor light emitting element according to the fifth embodiment of the present invention.

[0019] FIG8 is a schematic cross-sectional view showing a partial structure of a semiconductor light emitting element according to a fifth embodiment of the present invention.

[0020] FIG9 is a schematic cross-sectional view showing a light emitting element according to a sixth embodiment of the present invention. Modes for Carrying Out the Invention

[0021] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0022] The composition and dopant content of each layer in the light-emitting device of the present invention can be analyzed by any suitable method, such as secondary ion mass spectrometry (SIMS). The thickness of each layer in the light-emitting device of the present invention can be analyzed by any suitable method, such as transmission electron microscopy (TEM) or scanning electron microscopy (SEM), to coordinate the depth position of each layer on a SIMS map.

[0023] The relative intensities of the three group elements, such as Al / In / Ga, can be obtained from SIMS composition profile analysis of general epitaxial structures or EDX element analysis in TEM. The band gap can be determined by the intensity of the two elements Al / In. The higher the Al, the higher the band gap, and the higher the In, the lower the band gap.

[0024] In the present invention, unless otherwise specified, the term "peak shape" refers to a line profile consisting of two line segments with slopes of opposite signs, i.e., one segment has a positive slope and the other has a negative slope. "Peak concentration" refers to the highest concentration value between the two line segments of the peak shape with slopes of opposite signs.

[0025] Figure 1 is a cross-sectional view of a semiconductor light-emitting element according to the first embodiment of the present invention. Figure 2 is a graph showing the relationship between element concentration or ion intensity and depth for a portion of the semiconductor light-emitting element according to the first embodiment of the present invention. This graph can be obtained using a secondary ion mass spectrometer. The first embodiment of the present invention is a semiconductor light-emitting element with an upright structure, but is not limited thereto. Alternatively, the semiconductor light-emitting element (also known as an LED) can have a vertical or flip-chip structure. Figure 1 shows a schematic structural diagram of the light-emitting element, which comprises, from bottom to top, a semiconductor stack comprising an N-type semiconductor layer 120, a light-emitting layer 130, and a P-type semiconductor layer 140 deposited on a substrate 101. This series of semiconductor layers can be formed by, but is not limited to, metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), molecular beam epitaxy (MBE), and hydride vapor phase epitaxy (HVPE). In some embodiments, the substrate 101 may be thinned or removed. Furthermore, the semiconductor light emitting element may further include a first electrode 151 and a second electrode 152 . The first electrode 151 is electrically connected to the N-type semiconductor layer 120 , and the second electrode 152 is in ohmic contact with the P-type semiconductor layer 140 .

[0026] In an optional embodiment, the semiconductor stack of the light emitting element is an AlGaInN-based semiconductor material. The N-type semiconductor layer 120 is used to provide electrons to the light emitting layer 130 and is selected from a semiconductor material having a chemical formula In xAl y Ga 1-x-y N (0≤x≤1, 0≤y≤1, 0≤x1+y1≤1) semiconductor materials such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc., and may be doped with n-type dopants such as Si, Ge, Sn, Se, or Te. In the case of an ultraviolet light-emitting element, the N-type semiconductor layer may include AlGaN. Referring to FIG2 , the semiconductor stack contains the n-type impurity, and the n-type impurity has a concentration profile n1 along the thickness direction. The concentration profile n1 includes a first segment L1, a second segment L2, and a third segment L3, wherein the first segment L1 has a concentration greater than or equal to 5×10 18 atom / cm 3 The first concentration of the third segment L3 is less than 1×10 18 atom / cm 3 The second segment L2 connects the first segment L1 and the third segment L3 and reduces the concentration of the n-type impurities from the first concentration to the second concentration. Preferably, the N-type semiconductor layer 120 is mainly made of AlGaN material system, so the first concentration is preferably greater than or equal to 5×10 18 atom / cm 3 and less than 5×10 20 atom / cm 3 Controlling the concentration within this range can ensure a good ohmic contact interface and better control the crystal quality of the N-type semiconductor layer. When the concentration of the N-type doping is too high, it will affect the crystal quality of the semiconductor stack. The second concentration is preferably not higher than 5×10 17 atom / cm 3 , and the second concentration distribution thickness in the N-type semiconductor stack is greater than 10 nm. In a more preferred embodiment, the second concentration distribution thickness in the N-type semiconductor stack is greater than 20 nm and less than 250 nm, for example, can be 50 nm to 150 nm. Within this thickness range, the aging resistance and photoelectric characteristics of the light-emitting element can be better balanced.

[0027] Specifically, the N-type semiconductor layer 120 includes a first layer 121, a second layer 122 and a third layer 123, wherein the first layer 121 is Al x1 Ga 1-x1 N semiconductor layer, with a thickness greater than or equal to 5×10 18 Atom / cm 3 The first layer 121 has a sufficient doping concentration and thickness (usually more than 500 nm) to provide electrons and form an ohmic contact with the first electrode 151. The second layer 122 is located on the first layer and is Al x2 Ga1-x2 N semiconductor layer. Preferably, the second 122 has an n-type doping concentration lower than the first n-type doping concentration and higher than the band gap of the first layer. By properly adjusting the n-type doping concentration and band gap of the second layer, on the one hand, the light absorption effect of the semiconductor stack can be reduced, which helps to improve the luminous efficiency of the light-emitting element (especially the light-emitting element that emits short wavelengths such as ultraviolet light). On the other hand, the doping concentration of the second layer 122 is controlled to be lower than the N-type doping concentration of the first layer. When the current is injected into the first layer 121 through the first electrode, the current can be expanded in the second layer 122 to form a two-dimensional electron gas, thereby improving the internal quantum efficiency of the light-emitting element. Preferably, the second layer 122 has a thickness of 20~100nm, which can better expand the current. The third layer 123 is located above the second layer 122 and is adjacent to the light-emitting layer 130, with a thickness of less than 1×10 18 Atom / cm 3 Preferably, the n-type doping concentration of the third layer 123 is lower than 1×10 18 Atom / cm 3 The third layer 123 is located between the second layer 122 and the light emitting layer 130 and has the function of adjusting stress. Preferably, the third layer 123 is composed of Al x3 Ga 1-x3 N superlattice layer, the superlattice layer includes a periodic structure, each periodic structure generally includes at least two thin layer structures of different materials, and the material is a nitride-based semiconductor layer. In one embodiment, the superlattice layer includes an AlGaN / GaN periodic structure. In a preferred embodiment, at least one periodic structure includes multiple stacked layers, for example, GaN / AlGaN / AlN, InGaN / AlGaN / AlN or InGaN / GaN / AlN can be used. The periodic structure with a high energy gap can adjust the radiation recombination area, thereby improving the recombination efficiency of the light-emitting layer and thus improving the brightness, and can prevent the leakage formed by high-temperature hot holes or electrons obtaining additional energy, thereby improving the brightness stability of hot operation, and its hot / cold factor (Hot / cold factor, H / C) value can reach more than 70%.

[0028] In this embodiment, the first layer 122 corresponds to the first segment L1 of the concentration curve n1 shown in FIG. 2 , the second layer 122 corresponds to the second segment L2 of the concentration curve n1 , and the third layer 123 corresponds to the third segment L3 ( 123 ) of the concentration curve n1 .

[0029] In a preferred embodiment, the second layer 122 has an n-type doping concentration that varies along the thickness direction of the semiconductor stack, specifically decreasing from a first concentration to a second concentration. By designing the varying concentration, the current spreading function of the second layer 122 can be ensured, while the thickness of the second n-type doping concentration distributed across the semiconductor stack can be better controlled. In this embodiment, the second concentration is preferably no greater than 5×10 17 atom / cm 3 , and the distribution thickness D1 of the second concentration in the N-type semiconductor stack 120 is greater than or equal to 20nm and less than 250nm, that is, the thickness of the third semiconductor layer 123 is greater than or equal to 20nm and less than 250nm. By controlling the third layer 123 adjacent to the light-emitting layer 130 to have a low N-type doping concentration, it is beneficial to suppress the reverse leakage of the light-emitting element. More preferably, the second concentration is not higher than 1×10 17 atom / cm 3 , and the thickness of the third sublayer is not greater than 200 nm, which can better balance the forward voltage characteristics of the light-emitting element and suppress reverse leakage.

[0030] Furthermore, FIG2 also shows a curve A of the ion intensity and depth of the Al element in a partial range of a light-emitting element according to this embodiment (hereinafter referred to as Al ion intensity curve A), which is obtained using a secondary ion mass spectrometer. In one embodiment, the Al ion intensity in the N-type semiconductor conductor 120 increases layer by layer in the direction of the semiconductor stack, specifically, the Al ion intensity of the third layer 123 is the largest, the Al ion intensity of the second layer 122 is the second, and the Al ion intensity of the first layer 121 is the smallest, that is, X3>X2>X1. The lower Al component X1 of the first layer 121 is conducive to forming a good ohmic contact and forming a higher concentration of N-type doping in the first layer 121, while the third layer 123 has the highest Al component, which can increase the band gap of the layer, which is conducive to confining the carriers to the light-emitting layer and thereby improving the internal quantum efficiency of the light-emitting element, and further controlling the N-type doping concentration of the third layer to be less than or equal to 5×10 17 atom / cm 3 , increasing the resistivity of the semiconductor layer, thereby reducing the occurrence of reverse leakage under large current.

[0031] The light emitting layer 130 is formed on the N-type semiconductor layer 120. The light emitting layer 130 can be formed into a single quantum well or multiple quantum well structure, a quantum wire structure, a quantum dot structure, etc. using a compound semiconductor material composed of group III-V elements. In the light emitting diode of this embodiment, the light emitting layer 130 can have a quantum well structure and have a chemical formula In m Al n Ga 1-m-nN (0 ≤ m ≤ 1, 0 ≤ n ≤ 1, 0 ≤ m + n ≤ 1). The light-emitting layer 130 may have a single quantum well or a multi-quantum well structure. For example, it may include a plurality of barrier layers 131 and a plurality of well layers 132 arranged between the barrier layers. As shown in FIG. 3, according to an embodiment, the well layers 132 and the barrier layers 131 may be alternately arranged, and the number of well layers and barrier layers may be 3 to 8 layers. Each well layer may be formed of a material having a smaller bandgap energy than each barrier layer, that is, the relationship between the bandgap Eg1 of the well layer and the bandgap Eg2 of the barrier layer is Eg1 < Eg2. As the Al content of the well layer increases, the degree of freedom of the bandgap energy increases, the lattice constant increases, the luminous efficiency increases, and the wavelength of the emitted light shortens. In this embodiment, the N-type doping concentration of the light-emitting layer 130 is less than or equal to 5×10 17 atom / cm 3 ,More preferably, the N-type doping concentration of the light-emitting layer 130 is less than 1×10 17 atom / cm 3 . Controlling the N-type doping concentration of the light-emitting layer 130 is beneficial to further improving the anti-aging ability of the light-emitting element. When the N-type doping concentration of the light-emitting layer 130 exceeds 5×10 17 Atoms / cm 3 , it may accelerate the light decay of the light-emitting element at this time, especially severe light decay may occur under a large current.

[0032] The emission wavelength of the light-emitting diode can be determined according to the composition and thickness of the light-emitting layer 130. In a specific embodiment, the thickness ratio of the well layer 132 to the barrier layer 131 is between 1:1.7 and 1:2. On the one hand, it can generate light in the ultraviolet (UV) range with wavelengths of 3240 nm to 425 nm, and on the other hand, it can improve the internal quantum efficiency.

[0033] In some embodiments, the light-emitting layer 130 has a last barrier layer 133, and the thickness of the last barrier layer 133 is not less than 3 nm and not greater than 40 nm. If the thickness of the last barrier layer 133 is less than 3 nm, it is likely to cause leakage current. The last barrier layer 133 contains In j Al k Ga (1-j-k) N, where 0 ≤ j ≤ 1, 0 ≤ k ≤ 1. In one embodiment, the material of the last barrier layer 133 is the same as that of one of the barrier layers 123A. In a specific embodiment, the thickness of the last barrier layer 133 is greater than the thickness of one of the barrier layers 123A. More preferably, the thickness of the last barrier layer 133 is greater than the thickness of each of the other barrier layers 123A.

[0034] The P-type semiconductor layer 140 is located above the light-emitting layer 120 and includes an electron blocking layer 141 and a hole injection layer 142. The electron blocking layer 141 is located between the light-emitting layer 130 and the hole injection layer 142 and is formed of a semiconductor material with the chemical formula In z Al w Ga 1-z-w N (0 ≤ z ≤ 1, 0 ≤ w ≤ 1, 0 ≤ z + w ≤ 1) and has a lattice constant larger than that of the hole injection layer 142. In an ultraviolet light-emitting device, the electron blocking layer includes AlGaN. The electron blocking layer 141 may have a bandgap energy larger than that of the light-emitting layer 130. When a high current is applied, the electron blocking layer 141 prevents electrons injected from the N-type semiconductor layer 121 into the light-emitting layer 130 from recombining again in the active layer 123 and flowing into the hole injection layer 142, thereby increasing the probability of recombination between electrons and holes in the light-emitting layer 130 and thus preventing current leakage.

[0035] In a preferred embodiment, the electron blocking layer 141 includes In a Al b Ga 1-a-b N, where 0 ≤ a ≤ 0.05, 0 < b ≤ 1. If b is less than 0.05, the electrostatic discharge protection ability of the semiconductor light-emitting device will deteriorate. The electron blocking layer 141 is combined with the first electron blocking layer 124, which can further increase the light-emitting efficiency of the semiconductor device. In a preferred embodiment, the p-doping concentration of the electron blocking layer 141 is less than or equal to 5×10 19 Atoms / cm 3 Preferably, it is less than or equal to 2×10 19 Atoms / cm 3 and greater than or equal to 5×10 17 Atoms / cm 3 . When the p-type doping concentration of the electron blocking layer is less than or equal to 5×10 17 Atoms / cm 3 , it may cause the voltage of the light-emitting device to increase. In a preferred embodiment, the p-type doping concentration of the electron blocking layer is controlled to be between 2×10 19 Atoms / cm 3 and 1×10 18 Atoms / cm 3 . On the one hand, it is beneficial to control the voltage of the light-emitting device, and on the other hand, it can better control the p-type doping level of the light-emitting layer, making the light-emitting device have excellent anti-aging ability.

[0036] The hole injection layer 142 is formed on the electron blocking layer 141 and can be formed of a semiconductor compound for injecting holes into the light emitting layer 130. The hole injection layer 142 can be formed of a compound having a chemical formula of In c Al d Ga 1-c-d N (0≤c≤1, 0≤d≤1, 0≤c+d≤1), for example, selected from GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc., and doped with p-type dopants such as Mg, Zn, Ca, Sr or Ba. In UV light-emitting devices, the second semiconductor layer may include AlGaN. In one embodiment, the doping concentration of the hole injection layer 142 is less than or equal to 1×10 20 Atoms / cm 3 Furthermore, a contact layer (not shown in the figure) can be formed on the p-type hole layer 126. The p-type contact layer can be a highly doped p-type GaN layer or a p-type AlGaN layer. For example, the p-type doping concentration can be greater than 1×10 20 Atoms / cm 3 The p-type AlGaN layer is conducive to forming a good ohmic contact with the electrode.

[0037] In the light-emitting element described in this embodiment, the doping concentration of the third layer 123 and the light-emitting layer 130 is controlled to be lower than 5×10 17 Atoms / cm 3 , so that the depletion region formed between the N-type semiconductor layer and the P-type semiconductor layer has no redundant doping, thereby reducing the chance of leakage.

[0038] Please refer to Figure 4, which shows a cross-sectional view of a light-emitting element according to a second embodiment of the present invention. Unlike the light-emitting element shown in Figure 1, the electron blocking layer of this embodiment includes at least one V-shaped groove 160 extending toward the light-emitting layer 130, and the hole injection layer 142 fills this V-shaped groove 140. This V-shaped groove extends toward and forms within the light-emitting layer 130, preventing electrons or holes injected into the light-emitting layer from reaching threading dislocations, thereby effectively suppressing non-luminescent recombination within the light-emitting layer. Furthermore, the V-shaped groove 140 has a bottom portion A, which is located no lower than the starting point of the light-emitting layer 130 (i.e., the bottom surface of the first well layer near the N-type semiconductor layer). Preferably, this bottom portion A is preferably located within the light-emitting layer 130, thereby reducing leakage paths in the epitaxial structure and improving the luminous efficiency of the light-emitting element. Since at least a portion of the V-shaped groove is located in the light-emitting layer and the V-shaped groove 140 is filled by the p-type hole injection layer, controlling the depth of the V-shaped groove is beneficial to controlling the concentration level of the p-type impurities in the light-emitting layer 130. In one embodiment, the diameter of the top opening of the V-shaped groove is preferably less than or equal to 160 μm and the depth is less than 120 μm. This can better control the concentration of the p-type impurities in the light-emitting layer to be less than 5×10 17 Atoms / cm 3 , which is conducive to further improving the optoelectronic performance of light-emitting components.

[0039] In a preferred embodiment, the hole injection layer 142 has a fifth energy band gap Eg5 that is higher than the energy band gap Eg1 of the well layer 123B. Preferably, the fifth energy band gap Eg5 is lower than the energy band gap Eg2 of the barrier layer 131. In ultraviolet light-emitting elements, it is usually adopted to increase the energy band gap of the semiconductor layer to reduce the light absorption of the semiconductor layer. The band gap of the material can be adjusted by adjusting the Al component in the semiconductor layer. However, the semiconductor layer with a high Al component is not conducive to filling the V-shaped groove. In this embodiment, by controlling the energy band gap of the hole injection layer 142 to be higher than the energy band gap of the well layer and lower than the energy band gap of the barrier layer, it is ensured that the hole injection layer 142 can better fill the V-shaped groove, thereby reducing the leakage current of the light-emitting element and improving the pit aging ability of the light-emitting element.

[0040] In this embodiment, a V-shaped groove is formed in the semiconductor stack, which is beneficial to improving the hole-electron recombination efficiency of the light-emitting layer, controlling the bottom position and depth of the V-shaped groove, and adjusting the band gap of the p-type filling layer to be lower than the band gap of the barrier layer, so as to better fill the V-shaped groove, which can effectively limit the doping concentration of the p-type dopant in the light-emitting layer, thereby improving the aging performance of the light-emitting element.

[0041] FIG5 shows a graph showing the relationship between the concentration or ion intensity of an element and depth in a portion of a semiconductor light-emitting element according to another embodiment of the present invention. Unlike the first embodiment shown in FIG2 , the n-type impurity concentration curve n2 of the light-emitting element of this embodiment includes a peak P and a fourth segment L4. The peak P corresponds to the region between the third layer 123 and the light-emitting layer 130 in the semiconductor stack. By forming an N-type highly doped region between the light-emitting layer 130 and the third layer 123, the antistatic capability of the light-emitting element is improved. Preferably, the peak concentration of the peak P is less than 1×10 19 atom / cm 3 and greater than 5×10 17 atom / cm 3 In this embodiment, the peak concentration is about 2×10 18 atom / cm 3 In addition, the peak shape P includes a half-height width between 5 nm and 50 nm, and preferably between 5 nm and 20 nm. The fourth segment L4 corresponds to the light-emitting layer 130 in the semiconductor stack, and its concentration is preferably lower than the second concentration, and preferably, is lower than 1×10 17 atom / cm 3 , within this concentration range it helps to better suppress leakage.

[0042] This embodiment forms an n-type impurity concentration peak P between the third layer and the light-emitting layer, and controls the full width at half maximum of this peak P, thereby narrowing the depletion region between the N-type semiconductor layer and the P-type semiconductor layer, effectively improving the anti-static capability of the light-emitting element. Furthermore, when a V-shaped groove is formed in the light-emitting layer, the n-type impurity concentration in the light-emitting layer 130 is controlled to be lower than the second concentration, reducing the possibility of carrier leakage through the sidewalls of the V-shaped groove.

[0043] FIG6 shows a graph showing the relationship between element concentration or ion intensity and depth over a portion of a semiconductor light-emitting element according to another embodiment of the present invention. Unlike the first embodiment shown in FIG2 , in the n-type impurity concentration curve n3 of the light-emitting element according to this embodiment, the second segment L2 includes a first subsegment L21 and a second subsegment, wherein the slope of the first subsegment L21 is smaller than that of the second subsegment L22, meaning that the rate of concentration decrease in the first subsegment L21 is smaller than that in the second subsegment L22. In this embodiment, the concentration in the first subsegment L21 is greater than or equal to 1×10 18 atom / cm 3 and less than 1×10 19 atom / cm 3, and the thickness of the first sub-layer L21 distributed in the thickness direction of the semiconductor stack is more than three times the thickness of the second sub-layer L22 distributed in the thickness direction of the semiconductor stack, preferably more than five times. In this embodiment, the first sub-segment L21 mainly corresponds to the second layer 122, and the second sub-segment L22 corresponds to the interface between the second layer 122 and the third layer. Preferably, the second concentration corresponding to the third segment L3 is less than or equal to 1×10 17 atom / cm 3 Preferably, the N-type impurity concentration curve n3 may further include a fourth segment L5 connected to the third segment, and the fourth segment L5 corresponds to the concentration of n-type impurities contained in the light-emitting layer. In this embodiment, preferably, the fourth segment L5 decreases linearly in the light-emitting layer 130 and finally maintains at 1×10 16 atom / cm 3 Around the level.

[0044] In this embodiment, firstly, the concentration of n-type impurities in the second sub-layer is controlled to a certain level, which can better expand the current and improve the photoelectric conversion efficiency of the light-emitting element. Secondly, the concentration of the third layer 123 is further reduced to be less than or equal to 1×10 17 atom / cm 3 , which can effectively suppress the leakage risk caused by increasing the concentration of n-type impurities in the second layer 122. By linearly reducing the N-type doping in the light-emitting layer 123 and ultimately maintaining it at 1×10 16 atom / cm 3 level, can further suppress the occurrence of leakage.

[0045] FIG7 shows a graph showing the relationship between element concentration or ion intensity and depth over a portion of a semiconductor light-emitting element according to another embodiment of the present invention. Unlike the first embodiment shown in FIG2 , in the n-type impurity concentration curve n4 of the light-emitting element according to this embodiment, the second segment L2 includes a third subsegment L23 and a fourth subsegment. The slope of the third subsegment L23 is less than that of the fourth subsegment L24, meaning that the rate of concentration decrease in the third subsegment L23 is less than that in the fourth subsegment L24. Preferably, the concentration in the third subsegment L23 is greater than or equal to 1×10 18 atom / cm 3 and less than 1×10 19 atom / cm 3 , which can better spread the current and improve the photoelectric conversion efficiency of the light-emitting element. Preferably, the fourth sub-segment L24 decreases linearly. This helps maintain the overall concentration of the second segment L2 at a relatively high level while maintaining the concentration of the third segment L3 at a lower level, thereby improving the photoelectric characteristics of the light-emitting element.

[0046] Referring to FIG. 8 , in this embodiment, the third layer 123 can be divided into at least a first sublayer 123A and a second sublayer 123B, wherein the first sublayer 123A and the second sublayer are adjacent to the second layer 122, and the second sublayer 123B is adjacent to the light-emitting layer 130. Specifically, the first sublayer 123A and the second sublayer 123B can have substantially the same composition, differing primarily in the concentration of n-type impurities. Referring to FIG. 7 and FIG. 8 , the third subsegment L23 of the n-type impurity concentration curve n4 corresponds to the n-type impurity concentration of the second layer 122 of the N-type semiconductor layer 120, the fourth subsegment L24 corresponds to the n-type impurity concentration of the first sublayer 123A of the third layer 123, and the third subsegment L3 corresponds to the n-type impurity concentration of the second sublayer 123B of the third layer 123.

[0047] In this embodiment, the second concentration corresponding to the third segment L3 is less than or equal to 5×10 16 atom / cm 3 The thickness of the third segment L3 in the N-type semiconductor layer is preferably greater than 10 nm, preferably 10 nm to 150 nm, that is, the thickness of the second sub-layer 123B is preferably greater than or equal to 10 nm and less than or equal to 150 nm. In this embodiment, the second layer 122 has a relatively high concentration of n-type impurities (preferably greater than or equal to 1×10 18 atom / cm 3 Therefore, when the thickness of the second sublayer 123B of the third layer 123 is less than 10 nm, the leakage current suppression effect will be relatively weak; at the same time, the concentration of the n-type impurities in the second sublayer 123B is preferably less than or equal to 5×10 16 atom / cm 3 , the corresponding resistance increases. When the thickness of the second sub-layer 123B exceeds 150nm, the forward voltage of the light-emitting element will increase significantly. In a preferred embodiment, the thickness of the second sub-layer 123B can be 30-80nm.

[0048] In this embodiment, the third segment L3 of the curve n4 extends to the region where the light emitting layer 130 is located, and the concentration of the n-type impurities in the light emitting layer 130 is less than or equal to 5×10 16 atom / cm 3 At this time, the thickness of the third segment distributed in the semiconductor stack is preferably greater than or equal to 50nm and less than 300nm, so as to suppress leakage while taking into account the forward voltage level of the light-emitting element. In a preferred embodiment, the concentration of n-type impurities in the second sublayer of the third layer 123 is linearly reduced, and the concentration of n-type impurities in the light-emitting layer is finally maintained at 1×10 16 atom / cm 3 level, can further suppress the occurrence of leakage.

[0049] Figure 9 is a schematic cross-sectional view of a semiconductor light-emitting element according to another embodiment of the present invention. Specifically, the light-emitting element is a vertically structured light-emitting diode. From bottom to top, the light-emitting element comprises a conductive substrate 400 and a semiconductor layer sequence disposed above the conductive substrate 400. In some embodiments, a bonding metal and / or insulating dielectric film may be disposed between the conductive substrate 400 and the semiconductor layer sequence as a connecting layer 200.

[0050] The semiconductor layer sequence has sidewalls and opposing first and second surfaces, with the first surface being the front side and the second surface being the back side. The sequence includes an N-type semiconductor layer 120, a light-emitting layer 130, a first electron blocking layer 124, a second electron blocking layer 141, and a hole injection layer 142, sequentially arranged between the first and second surfaces. The N-type semiconductor layer can employ the structure shown in FIG8 , and the concentration distribution of n-type impurities in the N-type semiconductor layer and the light-emitting layer can be configured with reference to the relationship diagram shown in FIG7 . The second surface of the semiconductor layer sequence has a single or multiple recesses G, which penetrate at least the P-type semiconductor layer 140, the light-emitting layer 130, and a portion of the first layer 121 of the N-type semiconductor layer. Furthermore, the light-emitting diode also includes a first electrical connection layer 210, a second electrical connection layer 220, and an insulating layer. The second electrical connection layer 220 includes a transparent conductive layer 221, a metal reflective layer 222, and a metal connection layer 223 for contacting the semiconductor layer sequence. The first electrical connection layer 210 forms a protrusion within the recess G and is electrically connected to the N-type semiconductor layer 121 through the recess G. The first electrical connection layer 210 and the second electrical connection layer 220 are electrically isolated by the second insulating layer 310 and the third insulating layer 320. The first electrical connection layer 210 and / or the second electrical connection layer 220 comprise metal. The conductive substrate 400 serves as a first electrode and is electrically connected to the first electrical connection layer 210. The second electrical connection layer 220 is provided with a second electrode 420 on its upper surface. The first and second electrodes 420 are used to connect to an external circuit. Furthermore, a first insulating layer 310 can be provided between the second electrical connection layer 220 and the semiconductor layer sequence to improve the optoelectronic performance of the light-emitting element.

[0051] As a preferred embodiment of the present invention, a light emitting device is provided, which includes a circuit substrate and a light emitting element arranged on the circuit substrate, wherein the light emitting element may be the light emitting diode provided in the first embodiment of the present application. The light emitting device has excellent aging characteristics.

[0052] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A semiconductor light emitting element, comprising a semiconductor stack, wherein the semiconductor stack comprises an N-type semiconductor layer, a light emitting layer and a P-type semiconductor layer stacked in sequence, wherein the N-type semiconductor layer has a first surface and a second surface opposite to each other, and the second surface is close to the light emitting layer, characterized in that: At least part of the N-type semiconductor layer contains n-type impurities, and the n-type impurities have a concentration curve along the thickness direction of the semiconductor stack, and the concentration curve includes a first section, a second section and a third section, wherein the first section corresponds to a region of the N-type semiconductor layer away from the light-emitting layer, and has a concentration greater than or equal to 5×10 18 atom / cm 3 The first concentration, the third section corresponds to the region of the N-type semiconductor layer close to the light-emitting layer, with a concentration less than 1×10 18 atom / cm 3 The second segment connects the first segment and the third segment and reduces the concentration of the n-type impurity from the first concentration to the second concentration, wherein the thickness of the three segments distributed in the N-type semiconductor layer is greater than or equal to 10 nm.

2. The semiconductor light emitting element according to claim 1, characterized in that: The third segment of the curve extends toward the light-emitting layer, and the concentration of the n-type impurities in the light-emitting region is less than or equal to 5×10 16 atom / cm 3 .

3. The semiconductor light emitting element according to claim 2, characterized in that: The thickness of the third segment distributed in the semiconductor stack is greater than or equal to 50 nm and less than 300 nm.

4. The semiconductor light emitting element according to claim 1, characterized in that: The third concentration is less than or equal to 5×10 16 atom / cm 3 .

5. The semiconductor light emitting element according to claim 1, characterized in that: The second segment includes a first subsegment connected to the first segment and a second subsegment connected to the third segment, wherein a slope of the second subsegment is greater than a slope of the first subsegment.

6. The semiconductor light emitting element according to claim 5, characterized in that: The concentration of the first sub-segment is greater than or equal to 1×10 18 atom / cm 3 and less than or equal to 1×10 19 atom / cm 3 .

7. The semiconductor light emitting element according to claim 5, characterized in that: The second subsection decreases linearly.

8. The semiconductor light emitting element according to claim 1, characterized in that: The curve also includes a peak shape and a fourth segment, the peak shape connects the third segment and the fourth segment, and the peak concentration of the peak shape is less than 1×10 19 atom / cm 3 and greater than 5×10 17 atoms / cm.

9. The semiconductor light emitting element according to claim 8, characterized in that: The peak shape includes a half-height width between 5 nm and 50 nm.

10. The semiconductor light emitting element according to claim 8, characterized in that: The concentration of the third segment is less than 5×10 17 atom / cm 3 , the concentration of the fourth segment is less than 1×10 17 atom / cm 3 .

11. The semiconductor light emitting device according to claim 1, characterized in that: The N-type semiconductor layer includes a first layer, a second layer and a third layer, wherein the first layer is Al x1 Ga 1-x1 N semiconductor layer, whose doping concentration is greater than or equal to 5×10 18 atom / cm 3 , the second sub is Al x2 Ga 1-x2 N, the third layer contains Al x3 Ga 1-x3 N superlattice structure, wherein the doping concentration of the first layer is greater than the doping concentration of the second layer, and X1 <X2<X3。 12. The semiconductor light emitting element according to claim 11, characterized in that: The band gap of the third layer is higher than the band gap of the light-emitting layer, and the emission wavelength of the light-emitting layer is 340-425 nm.

13. The semiconductor light emitting device according to claim 1, characterized in that: The P-type semiconductor layer comprises an electron blocking layer and a hole injection layer, wherein the electron blocking layer is located between the light-emitting layer and the hole injection layer, the electron blocking layer has at least one V-shaped groove extending toward the light-emitting layer, and the hole injection layer fills the V-shaped groove.

14. The semiconductor light emitting element according to claim 13, characterized in that: The light emitting layer has a quantum well structure consisting of a barrier layer and a well layer, and the band gap of the hole injection layer is lower than the band gap of the barrier layer.

15. A semiconductor light emitting element, comprising a semiconductor stack, the semiconductor stack comprising an N-type semiconductor layer, a light emitting layer and a P-type semiconductor layer stacked in sequence, wherein the N-type semiconductor layer has a first surface and a second surface opposite to each other, wherein the second surface is close to the light emitting layer, characterized in that: The N-type semiconductor layer includes a first layer, a second layer and a third layer, wherein the first layer is Al x1 Ga 1-x1 N semiconductor layer, with a value greater than 5×10 18 atom / cm 3 The first n-type doping concentration is 1.0, and the third layer is Al x3 Ga 1-x3 N superlattice structure, the third layer is adjacent to the light-emitting layer, and the portion close to the light-emitting layer has a 18 atom / cm 3 The second n-type doping concentration of the portion is greater than or equal to 10 nm, and the second layer is Al x2 Ga 1-x2 The N semiconductor layer is located between the first layer and the second layer, and has an n-type doping concentration that is less than the first n-type doping concentration and greater than the second n-type doping concentration.

16. The semiconductor light emitting element according to claim 15, characterized in that: X1 <X2<X3。 17. The semiconductor light emitting element according to claim 15, characterized in that: The second n-type doping concentration is less than or equal to 1×10 17 atom / cm 3 .

18. The semiconductor light emitting element according to claim 15, characterized in that: The concentration of the n-type doping in the light-emitting region is less than or equal to 5×10 16 atom / cm 3 .

19. The semiconductor light emitting device according to claim 15, characterized in that: The third layer includes a first portion and a second portion, wherein the first portion is close to the second layer and has a gradually decreasing n-type doping concentration.

20. The semiconductor light emitting element according to claim 19, characterized in that: The second layer has a varying n-type doping concentration, the rate of which is less than a decreasing rate of the first portion of the third layer.

21. The semiconductor light emitting device according to claim 15, characterized in that: The P-type semiconductor layer comprises an electron blocking layer and a hole injection layer, wherein the electron blocking layer is located between the light-emitting layer and the hole injection layer, and the electron blocking layer has at least one V-shaped groove extending toward the light-emitting layer, and the hole injection layer fills the V-shaped groove.

22. The semiconductor light emitting element according to claim 21, characterized in that: The emission wavelength of the light-emitting layer is 340-425 nm, and the band gap of the hole injection layer is lower than the band gap of the light-emitting layer.

23. A semiconductor light emitting element, comprising a semiconductor stack, the semiconductor stack comprising an N-type semiconductor layer, a light emitting layer and a P-type semiconductor layer stacked in sequence, wherein the emission wavelength of the light emitting layer is 340-425 nm, characterized in that: The semiconductor stack has an n-type impurity concentration curve that changes along the thickness direction of the semiconductor stack, and the n-type impurity concentration curve has a value less than or equal to 5×10 16 atom / cm 3 The concentration of the semiconductor stack is greater than or equal to 50 nm and less than 300 nm.

24. The semiconductor light emitting device according to claim 23, characterized in that: The P-type semiconductor comprises an electron blocking layer and a hole injection layer, wherein the electron blocking layer is located between the light-emitting layer and the hole injection layer, and the electron blocking layer has at least one V-shaped groove extending toward the light-emitting layer, and the hole injection layer fills the V-shaped groove.

25. The semiconductor light emitting element according to claim 23, characterized in that: The N-type semiconductor layer includes a first Al x1 Ga 1-x1 N semiconductor layer, with a value greater than 5×10 18 atom / cm 3 The first n-type doping concentration, the second Al x2 Ga 1-x2 N semiconductor layer and Al x3 Ga 1-x3 N superlattice structure, wherein the superlattice structure has an n-type doping concentration that varies along the thickness direction of the semiconductor layer and decreases to less than 5×10 16 atom / cm 3 .

26. A light emitting device, characterized in that: It comprises the semiconductor light emitting element according to claims 1 to 25.

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