Deep ultraviolet LED device and epitaxial growth method thereof

Abstract

According to the deep ultraviolet LED device provided by the invention, a first stress regulation and control layer and a second stress regulation and control layer are sequentially arranged between an electron injection layer and a quantum well active layer, and the Al component content x2 of the first stress regulation and control layer and the Al component content x3 of the second stress regulation and control layer meet the following relations: x3 < = (x4 + x5) / 2, x2 > = (x1 + x3) / 2, x4 > x3 > x5; according to the invention, by regulating and controlling the Al component content of each layer, the lattice mismatch between the second stress regulation and control layer and the quantum well active layer is reduced, and the lattice mismatch among the electron injection layer, the first stress regulation and control layer and the second stress regulation and control layer is reduced, so that the tensile stress can be applied to the quantum well active layer, and the performance of the device is improved. Therefore, the pressure stress generated by the bottom epitaxial structure on the quantum well active layer is compensated, and the light-emitting efficiency of the deep ultraviolet LED device is finally improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor optoelectronics, and in particular to a deep ultraviolet LED device and an epitaxial growth method thereof. Background Art

[0002] In ultraviolet light, light with a wavelength of 200 nanometers to 350 nanometers is called deep ultraviolet light. Deep ultraviolet light-emitting diodes have great application value in lighting, sterilization, medical treatment, printing, biochemical detection, high-density information storage and confidential communication due to their advantages such as high efficiency, environmental protection, energy saving and reliability. These advantages are unmatched by ordinary ultraviolet light-emitting diodes. However, in the currently used high-Al component AlGaN-based deep ultraviolet LED devices, their quantum well active layers are usually subjected to large compressive stress from the underlying AlGaN layer, resulting in reduced luminous efficiency.

[0003] Therefore, it is necessary to propose a new deep ultraviolet LED device and its epitaxial growth method to solve the above problems existing in the prior art. Summary of the invention

[0004] The object of the present invention is to provide a deep ultraviolet LED device and an epitaxial growth method thereof, so as to improve the technical problem of low luminous efficiency of the deep ultraviolet LED device in the prior art.

[0005] In order to solve the above technical problems, the present invention provides a deep ultraviolet LED device, comprising a substrate, a buffer layer, an intrinsic layer, an electron injection layer, a first stress regulation layer, a second stress regulation layer, a quantum well active layer, an electron blocking layer, a hole injection layer and an ohmic contact layer which are sequentially stacked along a growth direction, wherein the quantum well active layer comprises at least one potential well layer and at least two potential barrier layers which are alternately arranged; Among them, the Al component contents in the electron injection layer, the first stress regulation layer, the second stress regulation layer, the barrier layer and the potential well layer are x1, x2, x3, x4 and x5 respectively, and satisfy the following relationship: x3≤(x4+x5) / 2, x2≥(x1+x3) / 2, x4>x3>x5.

[0006] Preferably, the first stress regulation layer is a single-layer AlGaN structure, the Al component content of the first stress regulation layer is 20% to 90%, and the thickness of the first stress regulation layer is 10 nm to 1000 nm.

[0007] Preferably, the first stress regulating layer includes a plurality of periodic structures, each of which includes a first sublayer and a second sublayer stacked in sequence along the growth direction, and the material of the first sublayer is Al a Ga 1-a N, the material of the second sublayer is Al b Ga 1-b N, a is the Al component content of the first sublayer, b is the Al component content of the second sublayer, and a and b satisfy the following relationship: 20%≤b≤a≤90%; The thickness of the first sublayer is 1 nm to 20 nm, the thickness of the second sublayer is 2 nm to 20 nm, and the number of periods of the first stress regulation layer is 2 to 50.

[0008] Preferably, the first stress regulating layer is a whole layer of N-type doped AlGaN material, and the doping concentration of the first stress regulating layer is 5E17cm -3 ~1E20cm -3 .

[0009] Preferably, the second stress regulation layer is a single-layer AlGaN structure, the Al component content of the second stress regulation layer is 10% to 80%, and the thickness of the second stress regulation layer is 2nm to 1000nm.

[0010] Preferably, the second stress regulating layer is a whole layer of N-type doped AlGaN material, and the doping concentration of the second stress regulating layer is 5E17cm -3 ~1E20cm -3 .

[0011] Preferably, the N-type doping concentrations in the electron injection layer, the first stress regulation layer, the second stress regulation layer and the barrier layer are y1, y2, y3 and y4 respectively, and satisfy the following relationship: y4≥y3 and y1≥y2>y3.

[0012] Accordingly, the present invention also provides an epitaxial growth method of the above deep ultraviolet LED device, the epitaxial growth method comprising: S10, epitaxially growing a buffer layer, an intrinsic layer and an electron injection layer on the substrate in sequence; S20, epitaxially growing a first stress regulating layer on the electron injection layer; S30, epitaxially growing a second stress regulating layer on the first stress regulating layer; S40, epitaxially growing a quantum well active layer, an electron blocking layer, a hole injection layer and an ohmic contact layer on the second stress regulating layer in sequence, wherein the quantum well active layer comprises at least one potential well layer and at least two potential barrier layers which are alternately arranged; Among them, the Al component contents in the electron injection layer, the first stress regulation layer, the second stress regulation layer, the barrier layer and the potential well layer are x1, x2, x3, x4 and x5 respectively, and satisfy the following relationship: x3≤(x4+x5) / 2, x2≥(x1+x3) / 2, x4>x3>x5.

[0013] Preferably, in step S20: the growth temperature of the first stress regulation layer is 800°C~1200°C, the first stress regulation layer is N-type doped AlGaN material, the Al component content of the first stress regulation layer is 20%~90%, and the thickness of the first stress regulation layer is 10nm~1000nm.

[0014] Preferably, in step S30: the growth temperature of the second stress regulation layer is 800°C~1200°C, the second stress regulation layer is N-type doped AlGaN material, the Al component content of the second stress regulation layer is 10%~80%, and the thickness of the second stress regulation layer is 2nm~1000nm.

[0015] The beneficial effects of the present invention are as follows: different from the prior art, the present invention sequentially arranges a first stress regulation layer and a second stress regulation layer between the electron injection layer and the quantum well active layer, and the Al component content x2 of the first stress regulation layer and the Al component content x3 of the second stress regulation layer satisfy the following relationship: x3≤(x4+x5) / 2, x2≥(x1+x3) / 2, x4>x3>x5; the present invention regulates the Al component content of the above-mentioned layers to reduce the lattice mismatch between the second stress regulation layer and the quantum well active layer, and at the same time reduces the lattice mismatch between the electron injection layer, the first stress regulation layer and the second stress regulation layer, so that tensile stress can be applied to the quantum well active layer, thereby compensating for the compressive stress generated by the underlying epitaxial structure on the quantum well active layer, and ultimately improving the luminous efficiency of the deep ultraviolet LED device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the cross-sectional structure of a deep ultraviolet LED device provided by an embodiment of the present invention; Figure 2 This is a process flow chart of the epitaxial growth method of a deep ultraviolet LED device provided in an embodiment of the present invention.

[0017] In the figure: 100 - deep ultraviolet LED device; 101 - substrate; 102 - buffer layer; 103 - intrinsic layer; 104 - electron injection layer; 105 - first stress regulation layer; 106 - second stress regulation layer; 107 - quantum well active layer; 108 - electron blocking layer; 109 - hole injection layer; 110 - ohmic contact layer; 111 - N-type electrode; 112 - P-type electrode. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In view of the technical problem of low luminous efficiency of the deep ultraviolet LED device 100 in the prior art, the present invention proposes a special deep ultraviolet LED device 100, which controls the Al component content of each epitaxial layer, applies tensile stress to the quantum well active layer 107, compensates for the compressive stress of the underlying epitaxial structure, and ultimately improves the luminous efficiency of the deep ultraviolet LED device 100.

[0020] See also Figure 1 , Figure 1 A schematic diagram of the cross-sectional structure of a deep ultraviolet LED device 100 provided in an embodiment of the present invention; wherein the present invention first provides a deep ultraviolet LED device 100, wherein the deep ultraviolet LED device 100 comprises a substrate 101, a buffer layer 102, an intrinsic layer 103, an electron injection layer 104, a first stress regulation layer 105, a second stress regulation layer 106, a quantum well active layer 107, an electron blocking layer 108, a hole injection layer 109 and an ohmic contact layer 110 which are sequentially stacked along a growth direction, wherein the quantum well active layer 107 comprises at least one potential well layer and at least two potential barrier layers which are alternately arranged; Among them, the Al component contents in the electron injection layer 104, the first stress regulation layer 105, the second stress regulation layer 106, the barrier layer and the potential well layer are x1, x2, x3, x4 and x5 respectively, and satisfy the following relationship: x3≤(x4+x5) / 2, x2≥(x1+x3) / 2, x4>x3>x5.

[0021] In the embodiment of the present invention, the substrate 101 is made of sapphire material. Sapphire material has many advantages: first, the production technology of sapphire material is mature and the device quality is good; second, sapphire has good stability and can be used in high-temperature growth processes; finally, sapphire has high mechanical strength and is easy to handle and clean. Therefore, most processes generally use sapphire as the substrate 101.

[0022] In the embodiment of the present invention, the material of the buffer layer 102 is AlN, the growth temperature thereof is in the range of 400° C. to 800° C., and the thickness thereof is in the range of 10 nm to 50 nm.

[0023] In the embodiment of the present invention, the material of the intrinsic layer 103 is AlN, the growth temperature thereof is in the range of 1200° C. to 1400° C., and the thickness thereof is in the range of 500 nm to 4000 nm.

[0024] In an embodiment of the present invention, the material of the electron injection layer 104 is Si-doped AlGaN material, and the dopant is SiH4; wherein the Al component content of the electron injection layer 104 is between 20% and 90%, the thickness of the electron injection layer 104 is between 500nm and 4000nm, and the growth temperature of the electron injection layer 104103 is between 800°C and 1200°C.

[0025] In the embodiment of the present invention, the first stress regulating layer 105 is disposed on the electron injection layer 104 , and the growth temperature of the first stress regulating layer 105 is in a range of 800° C. to 1200° C.

[0026] In the first embodiment, the first stress regulation layer 105 is a single-layer AlGaN structure, the Al component content of the first stress regulation layer 105 is 20% to 90%, and the thickness of the first stress regulation layer is 10 nm to 1000 nm.

[0027] In the second embodiment, the first stress regulating layer 105 includes a plurality of periodic structures, each of which includes a first sublayer and a second sublayer stacked in sequence along the growth direction. The material of the first sublayer is Al a Ga 1-a N, the material of the second sublayer is Al b Ga 1-b N, a is the Al component content of the first sublayer, b is the Al component content of the second sublayer, and a and b satisfy the following relationship: 20%≤b<a≤90%; The thickness of the first sub-layer is 1 nm to 20 nm, the thickness of the second sub-layer is 2 nm to 20 nm, and the number of periods of the first stress regulation layer 105 is 2 to 50.

[0028] Furthermore, multiple periodic structures can achieve more precise control of the performance of the first stress regulation layer 105. By adjusting the material parameters and thickness of the first sublayer and the second sublayer in each period, the characteristics such as the band structure and lattice matching can be precisely controlled; the periodic structure can be designed to have a specific band arrangement to form a quantum well or superlattice structure, which helps to improve the confinement ability of electrons and holes and improve the transport and recombination efficiency of carriers.

[0029] Furthermore, the relationship of 20%≤b<a≤90% ensures that the Al composition of the second sublayer does not exceed that of the first sublayer, forming a gradually changing Al composition distribution. This distribution can reduce lattice mismatch and interface stress, while providing a transition from low Al composition to high Al composition, which is beneficial to the absorption of impurities and the limitation of carriers.

[0030] Preferably, the first stress regulating layer 105 of the first embodiment and / or the second embodiment is a whole layer of N-type doped AlGaN material, and the doping concentration of the first stress regulating layer is 5E17cm -3 ~1E20cm -3 ; The first stress regulating layer 105 can control the stress state of the layer by adjusting the Al composition, thereby applying tensile stress to the quantum well active layer 107 to compensate for the stress effect of the bottom layer and improve the luminous efficiency of the deep ultraviolet LED device 100. The specific doping concentration range (5E17cm -3 ~1E20cm -3 ) can provide suitable electron concentration to ensure good conductivity and electron injection efficiency.

[0031] In an embodiment of the present invention, the growth temperature range of the second stress regulation layer 106 is between 800°C and 1200°C; the second stress regulation layer 106 is a single-layer AlGaN structure, the Al component content of the second stress regulation layer is 10% to 80%, and the thickness of the second stress regulation layer is 2nm to 1000nm.

[0032] Specifically, the second stress regulation layer 106 is a whole layer of N-type doped AlGaN material, and the doping concentration of the second stress regulation layer is 5E17cm -3 ~1E20cm -3 .

[0033] In the embodiment of the present invention, the quantum well active layer 107 is disposed on the second stress regulating layer 106, and the growth temperature range of the quantum well active layer 107 is between 700° C. and 1100° C. Specifically, the quantum well active layer 107 includes at least one potential well layer and at least two potential barrier layers that are alternately disposed, and each potential well layer is inserted between two adjacent potential barrier layers; wherein the potential well layer and the potential barrier layer both include AlGaN material, and the total content of aluminum components in each potential well layer is lower than the total content of aluminum components in each potential barrier layer, so as to ensure that the carriers in the quantum well active layer 107 are confined in the potential well layer.

[0034] Furthermore, the material of the potential well layer is Al x1 Ga y1 N, where 0<x1<80%, and x1+y1=1; the material of the barrier layer is Al x2 Ga y2 N, where 20%<x2<100%, and x2+y2=1.

[0035] Furthermore, the thickness of the potential well layer ranges from 0.1 nm to 5 nm, and the thickness of the barrier layer ranges from 5 nm to 30 nm; the period number of the quantum well active layer 107 is greater than or equal to 1 and less than or equal to 10, and the period number is a positive integer.

[0036] In an embodiment of the present invention, the Al component contents in the electron injection layer 104, the first stress regulation layer 105, the second stress regulation layer 106, the barrier layer and the potential well layer are x1, x2, x3, x4 and x5 respectively, and satisfy the following relationship: x3≤(x4+x5) / 2, x2≥(x1+x3) / 2, x4>x3>x5.

[0037] Specifically, the Al component content x3 of the second stress regulation layer 106 is less than half of the sum of the Al component contents of the barrier layer (x4) and the potential well layer (x5). This allows the second stress regulation layer 106 to play a transitional role near the quantum well active layer 107, which helps to optimize the energy band structure near the quantum well active layer 107. This avoids lattice mismatch and stress problems caused by excessive changes in the Al component, thereby improving the transmission efficiency of carriers in the quantum well active layer 107 and having a positive impact on the luminous efficiency.

[0038] Specifically, since x2≥(x1+x3) / 2, the first stress regulation layer 105 has a relatively high Al component content, which can block electron leakage and guide electron injection into the quantum well active layer 107. A larger x2 value may reduce the lattice constant of the first stress regulation layer 105, increase the lattice mismatch between the second stress regulation layer 106 and the quantum well active layer 107, and thus generate greater stress.

[0039] Specifically, due to x4>x3>x5, the Al component content of the second stress regulation layer 106 is at an intermediate level, which plays the role of connecting the electron injection layer 104 and the quantum well active layer 107, and also helps to optimize the energy band structure and stress distribution; the low Al component of the potential well layer provides a lower energy band, which is conducive to the recombination of electrons and holes.

[0040] Furthermore, the electron injection layer 104, the first stress regulation layer 105, and the second stress regulation layer 106 together constitute the surrounding environment of the quantum well active layer 107. By controlling the size of x1, x2, and x3, the lattice constant and stress state of the three layers of materials can be adjusted, thereby applying tensile stress to the quantum well active layer to compensate for the compressive stress of the underlying AlGaN material, thereby improving the luminous efficiency of the deep ultraviolet LED device 100.

[0041] In the embodiment of the present invention, the N-type doping concentrations in the electron injection layer 105 , the first stress regulation layer 106 , the second stress regulation layer 107 and the barrier layer 108 are y1, y2, y3 and y4 respectively, and satisfy the following relationship: y4≥y3 and y1≥y2>y3.

[0042] Specifically, the N-type doping concentration of the barrier layer is not lower than the N-type doping concentration of the second stress regulation layer 106. This relationship enables the barrier layer to have a relatively high electron concentration, which helps to enhance the electron confinement effect. The barrier layer serves as a blocking structure around the potential well layer. A higher N-type doping concentration can improve its conductivity and better prevent electrons from leaking out of the quantum well active layer 107, thereby improving the recombination efficiency of carriers in the quantum well and improving the luminous efficiency.

[0043] Specifically, the electron injection layer 104 requires a higher doping concentration to promote the effective injection of electrons from the external circuit into the deep ultraviolet LED device 100, and a higher y1 value can ensure good conductivity and electron injection efficiency; the doping concentration of the first stress regulation layer 105 is relatively moderate, which can not only cooperate with the electron injection layer 104 to improve the electron transmission efficiency, but also will not increase defects due to excessively high doping concentration; the lower doping concentration of the second stress regulation layer 106 may be to avoid the adverse effects of excessive doping concentration on other properties while regulating stress. For example, excessively high doping concentration may cause lattice distortion, increase scattering centers, etc., thereby reducing the carrier mobility and lifetime.

[0044] In the embodiment of the present invention, the electron blocking layer 108 is disposed on the quantum well active layer 107, and the growth temperature of the electron blocking layer 108 ranges from 700°C to 1100°C; wherein the electron blocking layer 108 is a single-layer Mg-doped AlGaN structure, which uses bismuthocene magnesium as a dopant.

[0045] In an embodiment of the present invention, the hole injection layer 109 is arranged on the electron blocking layer 108, and the growth temperature range of the hole injection layer 109 is between 700°C and 1100°C; wherein, the material of the hole injection layer 109 is P-type doped AlGaN material, the percentage of the aluminum component content in the hole injection layer 109 is between 0 and 100%, the thickness range of the hole injection layer 109 is between 1nm and 50nm, and the hole injection layer 109 uses dicyclopentadienyl magnesium as a dopant.

[0046] Preferably, the hole injection layer 109 is a whole layer of Mg doped with a doping concentration of 1E17 cm -3 ~1E19cm -3 .

[0047] In an embodiment of the present invention, the ohmic contact layer 110 is disposed on the hole injection layer 109, and the growth temperature range of the ohmic contact layer 110 is between 650°C and 950°C; wherein, the material of the ohmic contact layer 110 is P-type doped GaN material, the percentage of the aluminum component content in the ohmic contact layer 110 is between 0 and 100%, the thickness range of the ohmic contact layer 110 is between 1nm and 20nm, and the ohmic contact layer 110 uses dicyclopentadienyl magnesium as a dopant.

[0048] Furthermore, in an embodiment of the present invention, the deep ultraviolet LED device 100 also includes an N-type electrode 111 and a P-type electrode 112; wherein a step-like structure is formed between the first stress regulation layer 105 and the electron injection layer 104, and the area of ​​the first stress regulation layer 105 is smaller than the area of ​​the electron injection layer 104, the P-type electrode 112 is arranged on the ohmic contact layer 110, and the N-type electrode 111 is arranged at the step structure of the electron injection layer 104.

[0049] Accordingly, the present invention also provides a method for preparing a deep ultraviolet LED device 100, which is performed in a MOCVD (Metal-organic Chemical Vapor Deposition) device. Figure 1 as well as Figure 2 , Figure 2 for Figure 2 The process flow chart of the epitaxial growth method of the deep ultraviolet LED device 100 provided in the embodiment of the present invention; specifically, the epitaxial growth method includes: S10 , epitaxially growing a buffer layer 102 , an intrinsic layer 103 and an electron injection layer 104 in sequence on the substrate 101 .

[0050] Specifically, step S10 also includes: First, a substrate 101 is provided, and the substrate 101 is made of sapphire material; Secondly, at a growth temperature of 400° C. to 800° C., an AlN buffer layer 102 is epitaxially grown on the substrate 101 , with a thickness of 10 nm to 50 nm; Then, the temperature is raised to 1200° C. to 1400° C., and an intrinsic layer 103 made of AlN is epitaxially grown on the buffer layer 102 , with a thickness of 500 nm to 4000 nm; Finally, the temperature is lowered to 800° C. to 1200° C., and an electron injection layer 104 made of Si-doped AlGaN is epitaxially grown on the intrinsic layer 103 , wherein the Al component content is 20% to 90% and the thickness is 500 nm to 4000 nm.

[0051] S20, epitaxially growing a first stress regulating layer on the electron injection layer.

[0052] Specifically, step S20 also includes: The temperature is maintained at 800° C. to 1200° C., and a first stress regulation layer 105 is epitaxially grown on the electron injection layer 104; wherein the first stress regulation layer is an N-type doped AlGaN material, the Al component content of the first stress regulation layer 105 is 20% to 90%, and the thickness of the first stress regulation layer 105 is 10nm to 1000nm.

[0053] S30 , epitaxially growing a second stress regulating layer 106 on the first stress regulating layer 105 .

[0054] Specifically, step S30 also includes: The temperature is maintained at 800° C. to 1200° C., and a second stress regulation layer 106 is epitaxially grown on the first stress regulation layer 105; wherein the second stress regulation layer 106 is an N-type doped AlGaN material, the Al component content of the second stress regulation layer 106 is 10% to 80%, and the thickness of the second stress regulation layer 106 is 2nm to 1000nm.

[0055] S40, epitaxially growing a quantum well active layer 107, an electron blocking layer 108, a hole injection layer 109 and an ohmic contact layer 110 in sequence on the second stress regulating layer 106, wherein the quantum well active layer 107 includes at least one potential well layer and at least two potential barrier layers which are alternately arranged.

[0056] Specifically, step S40 also includes: First, the temperature is lowered to 700°C-1100°C, and a quantum well active layer 107 is epitaxially grown on the second stress regulation layer 106. The quantum well active layer 107 includes at least one potential well layer and at least two potential well layers alternately arranged. Each potential well layer is inserted between two adjacent potential barrier layers, and the materials of the potential well layer and the potential well layer are both AlGaN.

[0057] Secondly, the temperature is kept constant at 700° C. to 1100° C., and an electron blocking layer 108 is epitaxially grown on the quantum well active layer 107; Afterwards, the temperature is kept constant, and a hole injection layer 109 is epitaxially grown on the electron blocking layer 108; Afterwards, the temperature is lowered to 650° C. to 950° C., and an ohmic contact layer 110 is epitaxially grown on the hole injection layer 109 .

[0058] Then, an N-type electrode 111 is disposed at the step structure of the first electron injection layer 104 , and the N-type electrode 111 is disposed opposite to and spaced from the first stress regulation layer 105 ; finally, a P-type electrode 112 is formed on the ohmic contact layer 110 .

[0059] The technical solution of the present application is now described in conjunction with specific embodiments.

[0060] Embodiment 1 of the present invention: The film structure of the deep ultraviolet LED device 100 provided in Example 1 of the present invention is as follows along the growth direction: Substrate 101, made of sapphire material; The buffer layer 102 is made of AlN and has a thickness of 20 nm; The intrinsic layer 103 is made of AlN and has a thickness of 2000 nm; The electron injection layer 104 is made of Si-doped AlGaN material with an Al content of 70%, a thickness of 1500nm, and a Si doping concentration of 1E19cm -3 ; The first stress regulating layer 105 is a single-layer AlGaN structure with an Al component content of 63%, a thickness of 500 nm, and a Si doping concentration of 5E18 cm -3 ; The second stress regulating layer 106 is a single-layer AlGaN structure with an Al component content of 55%, a thickness of 500 nm, and a Si doping concentration of 2E18 cm -3 ; The quantum well active layer 107 includes at least one potential well layer and at least two potential barrier layers which are alternately arranged, each potential well layer is inserted between two adjacent potential barrier layers, and the number of cycles is 10; the material of the potential barrier layer is aluminum gallium nitride, the Al component content is 75%, and the thickness of the potential barrier layer is 10nm; the material of the potential well layer is aluminum gallium nitride, the Al component content is 50%, and the thickness of the potential well layer is 2nm; The electron blocking layer 108 is a single-layer Mg-doped AlGaN structure with a thickness of 10 nm; The hole injection layer 109 is made of Mg-doped AlGaN material, with an Al component content of 40% and a thickness of 20 nm, and uses bismuthocene magnesium as a P-type dopant; The ohmic contact layer 110 is made of Mg-doped GaN material and has a thickness of 10 nm.

[0061] Furthermore, a conventional method is used to set an N-type electrode 111 on the electron injection layer 104, and a P-type electrode 112 made of the same material as the N-type electrode 111 is set on the ohmic contact layer 110 to form a complete epitaxial chip structure, and the specific process is not described here. Among them, the N-type electrode 111 and the P-type electrode 112 are both multi-layer composite metal materials.

[0062] Embodiment 2 of the present invention: The film structure of the deep ultraviolet LED device 100 provided in Example 2 of the present invention is substantially the same as that and material of Example 1 of the present invention, except that: the first stress regulation layer 105 includes a plurality of periodic structures, each periodic structure includes a first sublayer and a second sublayer stacked in sequence along the growth direction, and the material of the first sublayer is Ala Ga 1-a N, the material of the second sublayer is Al b Ga 1-b N, a is the Al component content of the first sublayer, b is the Al component content of the second sublayer, a is 0.68, b is 0.58; The thickness of the first sublayer is 15 nm, the thickness of the second sublayer is 10 nm, and the number of periods of the first stress regulation layer 105 is 20. At this time, the calculation formula (1) for the Al component content x2 of the first stress regulation layer 105 is as follows: x2= (1); Wherein, t1 is the thickness of the first sub-layer, and t2 is the thickness of the second sub-layer.

[0063] Therefore, according to formula (1), the Al component content x2 of the first stress regulation layer 105 is 0.64, and its value satisfies: x2≥(x1+x3) / 2.

[0064] Comparative Example: The deep ultraviolet LED device 100 prepared by conventional process, the film layer structure of the deep ultraviolet LED device 100 provided in the comparative example is roughly the same as the structure and material of Example 1 of the present invention, the only difference is that: the first stress regulation layer 105 and the second stress regulation layer 106 are not arranged between the electron injection layer 104 and the quantum well active layer 107.

[0065] Furthermore, the optical power of the deep ultraviolet LED device 100 prepared in Examples 1 and 2 of the present invention and the voltage of the deep ultraviolet LED device 100 prepared in the comparative example at a current of 100 mA and the test results are shown in Table 1 below: Table 1 Test results of Example 1 of the present invention and comparative example sample Optical power at 100mA Voltage at 100mA Example 1 34.8mW 5.98V Example 1 36.5mW 6.04V Comparative Example 27.2mW 6.23V Specifically, it can be seen from Table 1 above that under the test conditions of 100mA, the deep ultraviolet LED device 100 prepared in Examples 1~2 of the present invention has higher optical power and lower operating voltage than the control example, which proves that the introduction of the first stress regulation layer 105 and the second stress regulation layer 106 is beneficial to improving the luminous efficiency of the deep ultraviolet LED device 100.

[0066] Furthermore, it can be seen from Table 1 above that the deep ultraviolet LED device 100 prepared in Example 2 of the present invention has higher optical power and lower operating voltage than that in Example 1 of the present invention; this shows that the first stress regulation layer 105 is further designed as a periodic structure, which is beneficial to improving the luminous efficiency of the deep ultraviolet LED device 100.

[0067] In summary, different from the prior art, the present invention sequentially arranges a first stress regulation layer 105 and a second stress regulation layer 106 between the electron injection layer 104 and the quantum well active layer 107, and the Al component content x2 of the first stress regulation layer 105 and the Al component content x3 of the second stress regulation layer 106 satisfy the following relationship: x3≤(x4+x5) / 2, x2≥(x1+x3) / 2, x4>x3>x5; the present invention regulates the Al component content of the above-mentioned layers to reduce the lattice mismatch between the second stress regulation layer 106 and the quantum well active layer 107, and at the same time reduces the lattice mismatch between the electron injection layer 104, the first stress regulation layer 105 and the second stress regulation layer 106, so that tensile stress can be applied to the quantum well active layer 107, thereby compensating for the compressive stress generated by the underlying epitaxial structure on the quantum well active layer 107, and ultimately improving the luminous efficiency of the deep ultraviolet LED device 100.

[0068] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For matters that are not described in detail in some embodiments, reference may be made to the description in other embodiments.

[0069] The above embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A deep ultraviolet LED device, characterized in that: It comprises a substrate, a buffer layer, an intrinsic layer, an electron injection layer, a first stress regulation layer, a second stress regulation layer, a quantum well active layer, an electron blocking layer, a hole injection layer and an ohmic contact layer which are sequentially stacked along a growth direction, wherein the quantum well active layer comprises at least one potential well layer and at least two potential barrier layers which are alternately arranged; Among them, the Al component contents in the electron injection layer, the first stress regulation layer, the second stress regulation layer, the barrier layer and the potential well layer are x1, x2, x3, x4 and x5 respectively, and satisfy the following relationship: x3≤(x4+x5) / 2, x2≥(x1+x3) / 2, x4>x3>x5.

2. The deep ultraviolet LED device according to claim 1, characterized in that: The first stress regulation layer is a single-layer AlGaN structure, the Al component content of the first stress regulation layer is 20% to 90%, and the thickness of the first stress regulation layer is 10nm to 1000nm.

3. The deep ultraviolet LED device according to claim 1, characterized in that: The first stress regulating layer includes a plurality of periodic structures, each of which includes a first sublayer and a second sublayer stacked in sequence along the growth direction, and the material of the first sublayer is Al a Ga 1-a N, the material of the second sublayer is Al b Ga 1-b N, a is the Al component content of the first sub-layer, b is the Al component content of the second sub-layer, and a and b satisfy the following relationship: 20%≤b<a≤90%; The thickness of the first sub-layer is 1 nm to 20 nm, the thickness of the second sub-layer is 2 nm to 20 nm, and the number of periods of the first stress regulation layer is 2 to 50.

4. The deep ultraviolet LED device according to any one of claims 2 to 3, characterized in that: The first stress regulation layer is a whole layer of N-type doped AlGaN material, and the doping concentration of the first stress regulation layer is 5E17cm -3 ~1E20cm -3 .

5. The deep ultraviolet LED device according to claim 1, characterized in that: The second stress regulation layer is a single-layer AlGaN structure, the Al component content of the second stress regulation layer is 10% to 80%, and the thickness of the second stress regulation layer is 2nm to 1000nm.

6. The deep ultraviolet LED device according to claim 5, characterized in that: The second stress regulation layer is a whole layer of N-type doped AlGaN material, and the doping concentration of the second stress regulation layer is 5E17cm -3 ~1E20cm -3 .

7. The deep ultraviolet LED device according to claim 1, characterized in that: The N-type doping concentrations in the electron injection layer, the first stress regulation layer, the second stress regulation layer and the barrier layer are y1, y2, y3 and y4 respectively, and satisfy the following relationship: y4≥y3 and y1≥y2>y3.

8. An epitaxial growth method for a deep ultraviolet LED device as claimed in claim 1, characterized in that: The epitaxial growth method comprises: S10, epitaxially growing the buffer layer, the intrinsic layer and the electron injection layer on the substrate in sequence; S20, epitaxially growing the first stress regulating layer on the electron injection layer; S30, epitaxially growing the second stress regulating layer on the first stress regulating layer; S40, epitaxially growing the quantum well active layer, the electron blocking layer, the hole injection layer and the ohmic contact layer in sequence on the second stress regulating layer, wherein the quantum well active layer includes at least one potential well layer and at least two potential barrier layers which are alternately arranged; Among them, the Al component contents in the electron injection layer, the first stress regulation layer, the second stress regulation layer, the barrier layer and the potential well layer are x1, x2, x3, x4 and x5 respectively, and satisfy the following relationship: x3≤(x4+x5) / 2, x2≥(x1+x3) / 2, x4>x3>x5.

9. The epitaxial growth method of a deep ultraviolet LED device according to claim 8, characterized in that: In the step S20: the growth temperature of the first stress regulation layer is 800°C~1200°C, the first stress regulation layer is N-type doped AlGaN material, the Al component content of the first stress regulation layer is 20%~90%, and the thickness of the first stress regulation layer is 10nm~1000nm.

10. The epitaxial growth method of a deep ultraviolet LED device according to claim 8, characterized in that: In the step S30: the growth temperature of the second stress regulation layer is 800°C~1200°C, the second stress regulation layer is N-type doped AlGaN material, the Al component content of the second stress regulation layer is 10%~80%, and the thickness of the second stress regulation layer is 2nm~1000nm.

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