Semiconductor light-emitting elements and light-emitting devices

Abstract

The present invention provides a semiconductor light-emitting element and light-emitting device, wherein the semiconductor light-emitting element comprises at least an N-type semiconductor layer, a light-emitting layer, and a p-type hole injection layer stacked from bottom to top. The light-emitting layer contains an Al component, and the Al component has a concentration curve comprising multiple sets of alternating platform, peak, and trough, wherein the trough is located between the peak and the platform and has an asymmetric structure, wherein the curve near the peak comprises at least a first curve segment and a second curve segment, wherein the first curve segment connects to the second peak, the second curve segment connects to the first curve segment, and the slope of the second curve segment is less than the slope of the first curve segment. The semiconductor light-emitting element of the present invention can effectively improve photoelectric performance.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices and apparatus, and particularly to a semiconductor light-emitting element and light-emitting device. Background Technology

[0002] A semiconductor light-emitting element is an inorganic semiconductor device that emits light through the recombination of electrons and holes. Ultraviolet (UV) light-emitting elements emit UV light and can be used in various fields, including curing polymer materials, sterilizing medical equipment, device components, and light sources for generating white light. Therefore, UV light-emitting elements have been increasingly applied in various fields.

[0003] The photoelectric performance of existing ultraviolet (UV) light-emitting devices is directly related to the quality of the quantum well in the light-emitting layer, impurity concentration, interface defects, and V-shaped pits. For example, the well layer material in the light-emitting layer of a UV light-emitting device is AlInGaN (with different doping depending on the emission peak wavelength), while the barrier layer is mostly composed of AlGaN. Therefore, the large difference in their lattice constants often leads to a large number of interface defects at the material interface, which in turn affects the photoelectric properties of the product. Summary of the Invention

[0004] The purpose of this invention is to provide a semiconductor light-emitting element and a light-emitting device, which can effectively improve the photoelectric performance of the light-emitting element.

[0005] A first aspect of this application provides a semiconductor light-emitting element, comprising at least an N-type semiconductor layer, a light-emitting layer, and a p-type hole injection layer stacked from bottom to top. The light-emitting layer contains an Al component, which has a concentration curve comprising multiple sets of alternating plateaus, peaks, and troughs. The troughs are located between the peaks and the plateaus and have an asymmetrical structure. The curve near the peak comprises at least a first curve segment and a second curve segment, wherein the first curve segment connects to the second peak, the second curve segment connects to the first curve segment, and the slope of the second curve segment is less than the slope of the first curve segment.

[0006] In some embodiments, the light emission wavelength of the well layer is 340~425nm.

[0007] In some embodiments, the light-emitting layer includes at least two barrier layers and a well layer and a blocking layer located between the two barrier layers, wherein the barrier layer corresponds to the plateau of the curve, the blocking layer corresponds to the peak, and the well layer corresponds to the trough.

[0008] In some embodiments, the well layer includes a first layer and a second layer, wherein the band gap of the first layer is higher than the band gap of the second layer but lower than the band gap of the barrier layer.

[0009] In some embodiments, the Al composition of the barrier layer is gradient.

[0010] In some embodiments, the energy level band gap of the p-type hole injection layer is lower than that of the energy level band gap of the barrier layer.

[0011] In some embodiments, the p-type doping concentration of the well layer closest to the p-type hole injection layer in the light-emitting layer is less than or equal to 5 × 10¹⁷ Atoms / cm³.

[0012] In some embodiments, the p-type doping concentration of the barrier layer is less than or equal to 1 × 10¹⁷ Atoms / cm³.

[0013] In some embodiments, the doping concentration of the p-type hole injection layer is less than or equal to 1×1020 Atoms / cm3.

[0014] In some embodiments, the semiconductor light-emitting element further includes an electron blocking layer located between the light-emitting layer and the p-type hole injection layer.

[0015] In some embodiments, the second electron blocking layer has at least one V-shaped groove extending toward the light-emitting layer, and the p-type hole injection layer fills the V-shaped groove.

[0016] In some embodiments, the upper part of the V-shaped groove begins at the upper surface of the second electron blocking layer, and the bottom is located within the light-emitting layer.

[0017] In some embodiments, the thickness ratio of the well layer to the barrier layer is between 1:1.7 and 1:2.

[0018] A second aspect of this application provides a light-emitting device comprising a substrate and a semiconductor light-emitting element mounted on the substrate, wherein the light-emitting element may be any of the aforementioned types.

[0019] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects of the invention and other beneficial effects may be realized and obtained by means of the structures particularly pointed out in the description, claims, etc. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0021] For convenience or clarity, the thickness and dimensions of each layer shown in the figure may be exaggerated, omitted, or drawn approximations. Additionally, the dimensions of the light-emitting devices do not perfectly reflect their actual dimensions.

[0022] Figure 1 A schematic diagram of the epitaxial structure of the light-emitting element according to the first embodiment of the present invention is shown.

[0023] Figure 2 A schematic diagram of the structure of the light-emitting layer of the light-emitting element according to the first embodiment of the present invention is shown.

[0024] Figure 3 The image shows a partial EDX curve of the light-emitting layer of the light-emitting element according to the first embodiment of the present invention.

[0025] Figure 4 A schematic diagram of the epitaxial structure of the light-emitting element according to a second embodiment of the present invention is shown.

[0026] Figure 5 A schematic diagram of the epitaxial structure of the light-emitting element according to a third embodiment of the present invention is shown.

[0027] Figure 6 A partial band diagram of the light-emitting element according to a third embodiment of the present invention is shown.

[0028] Figure 7 A schematic diagram of the structure of a light-emitting element according to a fourth embodiment of the present invention is shown.

[0029] Figure 8 A wavelength-brightness scatter plot of a light-emitting element according to an embodiment of the present invention is shown. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] The composition and dopants of each layer in the light-emitting element 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 element of the present invention can be analyzed by any suitable method, such as transmission electron microscopy (TEM) or scanning electron microscopy (SEM), in conjunction with, for example, the depth positions of each layer on a SIMS spectrum.

[0032] The relative intensities of group 3 elements such as Al, In, and Ga can be obtained from SIMS compositional profile analysis of general epitaxial structures or EDX elemental analysis in TEM. The intensity of Al and In elements can indicate the band gap; more Al results in a higher band gap, and more In results in a lower band gap.

[0033] The first preferred embodiment of the present invention is a gallium nitride-based light-emitting element, but it is not limited thereto. Alternatively, the semiconductor light-emitting element (also known as an LED, hereinafter referred to as a light-emitting diode) may have a conventional or flip-chip structure. Figure 1 A schematic diagram of the epitaxial structure used in the light-emitting diode is shown. From bottom to top, the epitaxial structure includes an n-type semiconductor layer 121, a superlattice layer 122, a light-emitting layer 123, an electron blocking layer 125, and a p-type hole injection layer 126. This epitaxial structure can be formed using methods such as 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), but is not limited to these methods. Furthermore, the light-emitting diode may include a growth substrate 110 or a supporting substrate.

[0034] In an optional embodiment, the epitaxial structure of the light-emitting diode is an AlGaInN-based semiconductor material. The n-type semiconductor layer 121, selected from materials with the chemical formula In, provides electrons to the light-emitting layer 123. x1 Al y1 Ga 1-x1-y1 Semiconductor materials of type N (0≤x1≤1, 0≤y1≤1, 0≤x1+y1≤1), such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc., may be doped with n-type dopants, such as Si, Ge, Sn, Se, or Te. In the case of UV light-emitting diodes, the n-type semiconductor layer may include AlGaN.

[0035] The superlattice layer 122 is located between the n-type semiconductor layer 121 and the light-emitting layer 123, and has the functions of adjusting stress and current spreading. The superlattice layer 122 includes a periodic structure, and each periodic structure generally includes at least two thin-layer structures of different materials, and the materials are nitride-based semiconductor layers. In one embodiment, the superlattice layer 122 includes an AlGaN / GaN periodic structure. In a preferred embodiment, at least one periodic structure includes a first sub-layer, a second sub-layer and a third sub-layer, for example, InGaN / AlGaN / AlN, GaN / AlGaN / AlN or InGaN / GaN / AlN can be adopted. The periodic structure with a high energy gap can adjust the radiative recombination region, so as to improve the recombination efficiency of the light-emitting layer and further enhance the brightness, and can prevent the leakage formed by high-temperature hot holes or electrons obtaining extra energy, and improve the brightness stability of hot-state operation, and its hot / cold factor (H / C) value can reach more than 70%.

[0036] The light-emitting layer 123 is formed on the superlattice layer 122. The light-emitting layer 123 can be formed of a compound semiconductor material composed of group III-V elements into a single quantum well or multi-quantum well structure, a quantum wire structure, a quantum dot structure, etc. In the light-emitting diode of the present embodiment, the light-emitting layer 123 can have a quantum well structure and has the chemical formula In x2 Al y2 Ga 1-x2-y2 N (0≤x2≤1, 0≤y2≤1, 0≤x2 + y2≤1). The light-emitting layer 123 can have a single quantum well or multi-quantum well structure, for example, it can include a plurality of barrier layers 123A and a plurality of well layers 123B arranged between the barrier layers 123A. According to the embodiment, the well layer 123B and the barrier layer 123A can be arranged alternately. The number of the well layer 123B and the barrier layer 123A can be 3 to 8 layers. Each well layer 123B can be formed of a material having a smaller bandgap energy than each barrier layer 123A, that is, the relationship between the bandgap Eg1 of the well layer 123B and the bandgap Eg2 of the barrier layer is Eg1 < Eg2. As the Al content of the well layer 123B increases, the degree of freedom of the bandgap energy increases, the lattice constant increases, the light-emitting efficiency increases, and the wavelength of the emitted light shortens. In one embodiment, the p-type doping concentration of the well layer closest to the p-type hole injection layer in the light-emitting layer 123 is less than or equal to 5×10 17 Atoms / cm 3 , and the p-type doping concentration of the remaining well layers is less than or equal to 1×10 17 Atoms / cm 3 . Controlling the p-type doping concentration of each well layer in the light-emitting layer 123, especially the p-type doping concentration of the last well layer close to the p side, is beneficial to improving the anti-aging ability of the light-emitting element. When the p-type doping concentration of the last well layer exceeds 1×1018 Atoms / cm 3 This could accelerate the long-term light decay of the light-emitting element, especially under high current, which could lead to more severe light decay.

[0037] Furthermore, in this embodiment, a barrier layer 123C is provided between at least two cycles of the barrier layer 123A and the well layer 123B of the light-emitting layer 123. This barrier layer 123C has a band gap Eg6, which is larger than the band gap Eg3 of the electron-blocking layer. In a specific embodiment, the barrier layer 123C may be made of a material with the chemical formula Al. c Ga 1-c The structure is composed of semiconductor material N, where 0.95 ≤ c ≤ 1. In the embodiment, at least two periodic structures have an additional confinement layer (Eg6) with a higher bandgap than the barrier layer (Eg2) grown on each stacked barrier layer 123A. The additional barrier provides a better confinement effect. During device operation, the bandgap caused by the applied bias voltage, if the difference between the bandgap Eg6 of the barrier layer and the bandgap Eg2 of the barrier layer is at least 1.5 eV, will generate a potential barrier spike of high bandgap. The bandgap design can prevent carrier overflow and increase radiative recombination efficiency.

[0038] Although inserting a high-bandgap barrier layer 123C between the barrier layer 123A and the well layer is beneficial to increasing the recombination efficiency of the light-emitting layer, the large difference in lattice constants between the barrier layer and the well layer often generates a large number of interface defects at their material junctions, which in turn affects the photoelectric properties of the light-emitting element to some extent. Therefore, preferably, the well layer 123B of the quantum well structure of at least two periods of the light-emitting layer 123 includes a first layer 123B0 and a second layer 123B1, wherein the first layer 123B0 is located between the barrier layer 123C and the second layer 123B1, that is, a quantum well structure S of one period sequentially includes a barrier layer 123A, a barrier layer 123C, a first layer 123B0, and a second layer 123B1. Figure 2 As shown. In other words, the well layer located between the two barrier layers includes a first layer and a second layer. The first layer 123B0 mainly reduces the lattice difference between the barrier layer and the second layer, while the second layer is mainly used for light emission. Therefore, in this embodiment, the lattice constant of the first layer 123B0 is between that of the barrier layer 123C and the well layer 123B, which can mitigate the problem of lattice mismatch during the transition between different materials, thereby improving the photoelectric properties. In a preferred embodiment, the first layer 123B0 has a seventh level band gap Eg7 that is larger than the band gap Eg1 of the well layer 123B and smaller than the band gap Eg2 of the barrier layer. For example, the first layer 123B0 can be made of a material with the chemical formula Al. d Ga 1-dThe material is composed of N semiconductors with 0 ≤ c ≤ 0.5, which allows for better control of the emission wavelength of the light-emitting layer and promotes radiative recombination of holes and electrons in the second layer. This increases the radiative recombination efficiency of the light-emitting layer while avoiding severe light decay caused by numerous interface defects in the light-emitting element.

[0039] The emission wavelength of a light-emitting diode can be determined based on the composition and thickness of the light-emitting layer 123. In a specific embodiment, the thickness ratio of the well layer 123B to the barrier layer 123A is between 1:1.7 and 1:2. This can generate ultraviolet (UV) light in the wavelength range of 3240nm to 425nm, and also improve the internal quantum efficiency.

[0040] Figure 3 This diagram displays EDX concentration intensity curves of various components in a local portion of the light-emitting layer of a light-emitting element according to an embodiment of the present invention. Specifically, it includes a concentration curve showing the Al component, where the X-axis represents thickness and the Y-axis represents concentration intensity. The curve contains multiple alternating plateaus G, peaks P, and troughs T. Plateau G simply indicates that the fluctuations in this segment of the curve are smaller than those of peaks P and troughs T (this fluctuation may be due to test noise or intentional modulation of the Al content in this segment), and it has a certain width, with a concentration between peaks P and troughs T. In some embodiments, the Al component in this plateau segment may also be gradually increased, for example, gradually increasing from the side closer to the trough towards the side closer to the peak. In this embodiment, plateau G corresponds to barrier layer 123A, which has the greatest thickness; peak P represents blocking layer 123C, which has the smallest thickness; and trough corresponds to well layer 123B, whose thickness is between the peak and the plateau, i.e., the half-width of the trough is greater than the half-width of the peak. Furthermore, the trough T is not symmetrical. On the side closer to the platform G, curve T1 consists of a relatively smooth transition curve, while on the side closer to the peak P, curve T2 includes a first segment L1 and a second segment L2. The first segment L1 connects to the peak P, and the second segment L2 connects curves L1 and T1. In this embodiment, the second segment can be implemented by inserting a first layer with a bandgap between the blocking layer 123C and the well layer 123B1. For example, this could be a GaN layer or a low-Al content AlGaN layer, forming a buffer zone. In a preferred embodiment, the second segment L2 can form a small step. This small step reduces the abrupt change in Al content between the peak and trough, thus reducing the lattice difference between the blocking layer and the well layer. It also better confines the holes and electrons flowing into the luminescent layer within the second layer for radiative emission, increasing radiative recombination efficiency and wavelength consistency.

[0041] In some embodiments, the light-emitting layer 123 has a last barrier layer 123D, the thickness of which is not less than 3 nm and not more than 40 nm. A thickness less than 3 nm in the last barrier layer 123D would result in leakage current. The last barrier layer 123D 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 123D is the same as the material of one of the barrier layers 123A. In a specific embodiment, the thickness of the last barrier layer 123D is less than the thickness of one of the barrier layers 123A; preferably, the thickness of the last barrier layer 123D is less than the thickness of each of the other barrier layers 123A. In one embodiment, the p-type doping concentration of the last barrier layer is less than or equal to 1 × 10⁻⁶. 18 Atoms / cm 3 The p-type doping concentration of the remaining barrier layer 123A is less than or equal to 1 × 10⁻⁶. 17 Atoms / cm 3 Preferably, the p-type doping concentration of the last barrier layer 123D is less than or equal to 5 × 10⁻⁶. 17 Atoms / cm 3 Controlling the p-type doping concentration of each barrier layer in the light-emitting layer 123, especially the p-type doping concentration of the last barrier layer near the p-side, is beneficial to improving the anti-aging ability of the light-emitting device. When the p-type doping concentration of the last well layer exceeds 1×10 18 Atoms / cm 3 This could accelerate the long-term light decay of the light-emitting element, especially under high current, which could lead to severe light decay.

[0042] The electron blocking layer is located between the light-emitting layer 123 and the p-type hole injection layer 126, and is composed of an In-type electron blocking layer. z Al w Ga 1-z- w A semiconductor material of type N (0≤z≤1, 0≤w≤1, 0≤z+w≤1) is formed, and it has a larger lattice constant than the p-type hole injection layer 126. In the UV light-emitting diode, the electron blocking layer includes AlGaN. The electron blocking layer 126 can have a larger bandgap energy than the light-emitting layer 123. When a high current is applied, the electron blocking layer 126 prevents electrons injected from the n-type semiconductor layer 121 into the light-emitting layer 123 from recombinating in the active layer 123 and flowing to the p-type hole injection layer 126, thereby increasing the probability of recombination between electrons and holes in the light-emitting layer 123 and thus preventing current leakage.

[0043] In a preferred embodiment, the electron blocking layer 125 contains 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 125 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 125 is less than or equal to 5×10 19 Atoms / cm 3 , more preferably, 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, so that the light-emitting device has excellent anti-light decay ability.

[0044] The p-type hole injection layer 126 is formed on the electron blocking layer 125 and can be formed of a semiconductor compound for injecting holes into the light-emitting layer 123. The p-type hole injection layer 126 is, for example, formed of a semiconductor material having the chemical formula In x2 Al y2 Ga 1-x2-y2 N (0 ≤ x2 ≤ 1, 0 ≤ y2 ≤ 1, 0 ≤ x2 + y2 ≤ 1), for example, selected from GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc., and doped with a p-type dopant such as Mg, Zn, Ca, Sr or Ba. In a UV light-emitting device, the second semiconductor layer may include AlGaN. In one embodiment, the doping concentration of the p-type hole injection layer 126 is less than or equal to 1×10 20 Atoms / cm 3 . Further, 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, a p-type doping concentration greater than 1×10 20 Atoms / cm3 The p-type AlGaN layer is beneficial for forming good ohmic contact with the electrode.

[0045] Please refer to Figure 4 This illustrates the epitaxial structure of a light-emitting diode disclosed in the second preferred embodiment of the present invention. Figure 1 Unlike the epitaxial structure shown elsewhere, in this embodiment, the electron blocking layer has at least one V-shaped groove 140 extending toward the light-emitting layer 123, and the p-type hole injection layer 126 fills the V-shaped groove 140. This V-shaped groove extends toward and is formed within the light-emitting layer 123, thus preventing electrons or holes injected into the light-emitting layer from reaching penetrating dislocations, thereby suppressing non-luminescent recombination in the light-emitting layer. Furthermore, the V-shaped groove 140 has a bottom A, the position of which is not lower than the initial position of the light-emitting layer 123 (i.e., the bottom surface of the first well layer near the n-type semiconductor layer). Preferably, the bottom A is located within the light-emitting layer 123, thereby reducing the leakage path 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 within 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 for controlling the concentration level of p-type impurities in the light-emitting layer 123. 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 allows for better control of the concentration of p-type impurities in the light-emitting layer to be below 5 × 10⁻⁶. 17 Atoms / cm 3 .

[0046] In a preferred embodiment, the p-type hole injection layer 126 has a fifth band gap Eg5, which is higher than the band gap Eg1 of the well layer 123B. Preferably, the fifth band gap Eg5 is lower than the band gap Eg2 of its barrier layer 123A. In UV light-emitting devices, increasing the band gap of the semiconductor layer is typically used to reduce light absorption. The band gap of the material can be adjusted by changing the Al composition in the semiconductor layer; however, a semiconductor layer with a high Al composition is disadvantageous for filling V-shaped grooves. In this embodiment, by controlling the band gap of the p-type hole injection layer 126 to be higher than the band gap of the well layer and lower than the band gap of the barrier layer, it is ensured that the p-type hole injection layer 126 can fill the V-shaped grooves well, thereby reducing leakage current of the light-emitting device and improving the pit aging resistance of the light-emitting device.

[0047] In this embodiment, a V-shaped groove is formed in the epitaxial structure, which is beneficial to improving the hole-electron recombination efficiency of the light-emitting layer. The bottom position and depth of the V-shaped groove are controlled, and the bandgap of the p-type filling layer is adjusted to be lower than that of the barrier layer, so as to better fill the V-shaped groove, and the doping concentration of the p-type dopant in the light-emitting layer can be well restricted, thereby improving the aging performance of the light-emitting element.

[0048] Figure 5 shows the epitaxial structure of a light-emitting diode according to another preferred embodiment of the present invention. Different from Figure 4 Embodiment 2 shown, in this embodiment, the electron blocking layer includes a first electron blocking layer 124 and a second electron blocking layer 125.

[0049] In a preferred embodiment, the electron blocking layer includes a first electron blocking layer 124 and a second electron blocking layer 125, wherein the first electron blocking layer 124 directly contacts the last barrier layer 123D, as Figure 5 shown. The first electron blocking layer 124 has a third energy level bandgap Eg3, the second electron blocking layer 125 has a fourth energy level bandgap Eg4, and the third energy level bandgap Eg3 is greater than the fourth energy level bandgap Eg4. The first electron blocking layer 124 contains Al g Ga 1-g N, where 0.5 < g ≤ 1, and preferably, 0.7 < g ≤ 1. In a specific implementation mode, the first electron blocking layer 124 contains AlN. In this embodiment, the first electron blocking layer 124 has a thickness that is not less than 0.5 nm and not greater than 15 nm, more preferably, not greater than 5 nm. The thickness of the first electron blocking layer 124 is between 0.5 nm and 15 nm, and the thickness within this range can reduce the diffusion of p-type dopants into the light-emitting layer 123. If the thickness of the first electron blocking layer 124 is less than 0.5 nm, its ability to block the diffusion of p-type dopants into the light-emitting layer 123 will deteriorate and the electrostatic discharge protection ability of the semiconductor device will become poor. If the thickness of the first electron blocking layer 124 is greater than 15 nm, the electrical properties (such as forward voltage or leakage current) of the semiconductor light-emitting device will become poor. In a preferred embodiment, the p-type doping concentration of the first electron blocking layer 124 is less than or equal to 1×10 18 Atoms / cm 3 .

[0050] The fourth energy level bandgap Eg4 of the second electron blocking layer 125 is greater than the energy level bandgap Eg2 of one of the barrier layers 123A in the light-emitting layer 123. Preferably, the fourth energy level bandgap Eg4 of the second electron blocking layer 125 is greater than the energy level bandgap Eg2 of the first barrier layer 123A. The second electron blocking layer 125 contains In a Al b Ga 1-a-bN, 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 second electron blocking layer 125 and the first electron blocking layer 124 can be combined to further increase the light-emitting efficiency of the semiconductor device. In a preferred embodiment, the p-doping concentration of the second electron blocking layer 125 is less than or equal to 5×10 19 Atoms / cm 3 , more preferably, less than or equal to 2×10 19 Atoms / cm 3 .

[0051] Figure 6 shows the magnitude relationship of the energy band gaps of each layer in the epitaxial structure from the light-emitting layer 123 to the p-type hole injection layer 126 in a preferred embodiment of the present invention, specifically, Eg3 > Eg4 > Eg2 > Eg5 > Eg1, and Eg6 > Eg2 > Eg7 > Eg1. In this embodiment, by controlling the energy band gap of the p-type hole injection layer 126 to be lower than that of the barrier layer, it is ensured that the p-type hole injection layer 126 can better fill the V-shaped groove, thereby reducing the leakage current occurrence of the light-emitting device. Further, the structure of the first and second electron blocking layers can limit the p-type dopant doping concentration in the light-emitting layer, effectively improving the light efficiency and anti-aging ability of the light-emitting device. In a preferred embodiment, the Al group at one end of the barrier layer 123A close to the well layer can increase first and then remain unchanged, which is beneficial to reducing the lattice mutation at the interface between the well layer and the barrier layer and improving the internal quantum well efficiency of the light-emitting device.

[0052] Figure 7 shows a schematic structural diagram of a light-emitting diode implemented according to the present invention. Refer to Figure 7 , a vertical structure light-emitting diode is provided. From bottom to top, the light-emitting diode includes a conductive substrate 400, a semiconductor layer sequence disposed above the conductive substrate 400, and in some embodiments, a bonding metal and / or an insulating dielectric film can be disposed between the conductive substrate 400 and the semiconductor layer sequence as a connection layer 200.

[0053] The semiconductor layer sequence has sidewalls and opposite first and second surfaces. The first surface is the positive side, and the second surface is the back side, including an n-type semiconductor layer 121, a superlattice layer 122, a light-emitting layer 123, a first electron blocking layer 124, a second electron blocking layer 125, and a p-type hole injection layer 126 arranged in sequence between the first surface and the second surface. The structure of the light-emitting layer 123 can refer to Figure 2The structure shown has a second surface of the semiconductor layer sequence having one or more recesses G2, each recess G2 penetrating at least the p-type hole injection layer 126, the light-emitting layer 123, and a portion of the n-type semiconductor layer 121. Further, 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 100. The first electrical connection layer 210 forms a protrusion within the recess G2 and is electrically connected to the n-type semiconductor layer 121 through the recess G2. The first electrical connection layer 210 and the second electrical connection layer 220 are electrically isolated by a second insulating layer 310 and a 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 the first electrode and is electrically connected to the first electrical connection layer 210. A second electrode 420 is disposed on the upper surface of the second electrical connection layer 220. The first electrode and the second electrode 420 are used for connection to an external circuit. Furthermore, a first insulating layer 310 can be disposed between the second electrical connection layer 220 and the semiconductor layer sequence, which is beneficial to improving the photoelectric performance of the light-emitting element.

[0054] The following describes the fabrication of two types of ultraviolet LED vertical chip samples with a main emission wavelength of 365-370nm. Their specific structures can be found in [reference needed]. Figure 7 The structure shown uses a silicon substrate as the conductive substrate, and the chip size is 45mil × 45mil. In the epitaxial structures of Sample 1 and Sample 2, except for the light-emitting layer 123, the composition and thickness of the other semiconductor layers are identical. The N-type semiconductor layer is AlGaN, and the p-type hole injection layer is AlGaN. Specifically, the light-emitting layer 123 of Sample 1 uses AlGaN. z3 Ga 1-z3 N (z content 8 at, average layer thickness 12 nm) / AlN (average layer thickness 0.7 nm) / In x3 Ga 1-x3 Three N (x3 content of 0.5 at%, average layer thickness of 7 nm) layers are stacked alternately, with a period of 5. Sample 2 uses... Figure 5 The epitaxial structure shown has an emitting layer 123 specifically made of Al. z3 Ga 1-z3 N (z content 8 at%, average layer thickness 11 nm) / AlN (average layer thickness 0.7 nm) / GaN (average layer thickness approximately 2 nm) / In x3 Ga 1-x3 Four N layers (x3 content of 0.5 at, average layer thickness of about 5 nm) are stacked alternately, with a period of 5, and the other layers are the same as those in sample 1.

[0055] Figure 8The wavelength-brightness scatter plots of Sample 1 and Sample 2 at a current of 500mA are shown. Since the carrier disk used in MOCVD epitaxial wafer growth has a circular structure, epitaxial wafers at different positions on the carrier disk will result in different growth qualities. Therefore, two epitaxial wafer samples from Sample 1 and Sample 2 at the same position on the carrier disk are compared. Figure 8 As can be seen, the emission wavelengths of both samples are distributed in the band of 365-370nm. The luminescence brightness of the two samples of sample 2 is significantly higher than that of sample 3, that is, the brightness of sample 2 is significantly improved.

[0056] The two samples were subjected to aging tests. The specific measurement conditions were an ambient temperature of 45℃ and an aging current of 3000mA. After 48 hours, the brightness of sample one decreased by 87.71%, and the brightness of sample two decreased by 90.91%. That is, under high current, the light decay of sample two is slower.

[0057] Furthermore, the two samples were tested for the hot / cold state factor H / C. The specific results are shown in the table below. It can be seen that sample two significantly improved the brightness stability during hot operation.

[0058]

[0059] As a preferred embodiment of the present invention, a light-emitting device is provided, which includes a circuit board and a light-emitting element disposed on the circuit board, wherein the light-emitting element may be a light-emitting diode provided in Embodiment 1 of this application. This light-emitting device has excellent aging characteristics.

[0060] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A semiconductor light-emitting element, comprising at least an N-type semiconductor layer, a light-emitting layer, and a p-type hole injection layer stacked from bottom to top, characterized in that: The light-emitting layer contains an Al component, which has a concentration curve. The curve includes multiple sets of alternating plateaus, peaks, and troughs. The troughs are located between the peaks and the plateaus and have an asymmetrical structure. The curve near the peak includes at least a first curve segment and a second curve segment. The first curve segment connects to the peak, and the second curve segment connects to the first curve segment. The slope of the second curve segment is less than the slope of the first curve segment. The light-emitting layer includes at least two barrier layers and a well layer and a blocking layer sandwiched between the two barrier layers. The barrier layer corresponds to the plateau of the curve, the blocking layer corresponds to the peak, and the well layer corresponds to the trough.

2. The semiconductor light-emitting element according to claim 1, characterized in that: The light emission wavelength of the well layer is 340~425nm.

3. The semiconductor light-emitting element according to claim 1, characterized in that: The well layer includes a first layer and a second layer, wherein the energy level band gap of the first layer is higher than that of the second layer but lower than that of the barrier layer.

4. The semiconductor light-emitting element according to claim 1, characterized in that: The Al composition of the barrier layer is gradually varied.

5. The semiconductor light-emitting element according to claim 1, characterized in that: The energy level band gap of the p-type hole injection layer is lower than that of the energy level band gap of the barrier layer.

6. The semiconductor light-emitting element according to claim 1, characterized in that: The p-type doping concentration of the well layer closest to the p-type hole injection layer in the light-emitting layer is less than or equal to 5 × 10⁻⁶. 17 Atoms / cm 3 .

7. The semiconductor light-emitting element according to claim 1, characterized in that: The p-type doping concentration of the barrier layer is less than or equal to 1 × 10⁻⁶. 17 Atoms / cm 3 .

8. The semiconductor light-emitting element according to claim 1, characterized in that: The doping concentration of the p-type hole injection layer is less than or equal to 1×10⁻⁶. 20 Atoms / cm 3 .

9. The semiconductor light-emitting element according to claim 1, characterized in that: It includes an electron blocking layer located between the light-emitting layer and the p-type hole injection layer.

10. The semiconductor light-emitting element according to claim 9, characterized in that: The electron blocking layer has at least one V-shaped groove extending toward the light-emitting layer, and the p-type hole injection layer fills the V-shaped groove.

11. The semiconductor light-emitting element according to claim 10, characterized in that: The upper part of the V-shaped groove starts from the upper surface of the electron blocking layer, and the bottom is located in the light-emitting layer.

12. The semiconductor light-emitting element according to claim 1, characterized in that: The thickness ratio of the well layer to the barrier layer is between 1:1.7 and 1:

2.

13. The semiconductor light-emitting element according to claim 1, characterized in that: The second curve segment forms a step.

14. A light-emitting device, characterized in that, It includes the semiconductor light-emitting element as described in any one of claims 1-13.

Images