An LED epitaxial structure and its fabrication method

Abstract

This invention relates to the technical field of light-emitting diodes (LEDs), and discloses an LED epitaxial structure and its fabrication method. The LED epitaxial structure includes a substrate, a buffer layer, a three-dimensional GaN layer, an undoped GaN layer, an N-type semiconductor layer, a stress-relieving layer, a multi-quantum-well (MBU) emitting layer, an electron-blocking layer, and a P-type semiconductor layer, stacked sequentially. The MBU is a periodic structure, with each period comprising a sequentially stacked quantum well layer and a quantum barrier layer. The quantum well layer is an InGaN layer. Along the growth direction, the In content of the quantum well layer in the last period is less than that in any other period. Implementing this invention can reduce the quantum confinement Stark effect, improve hole injection balance, and optimize carrier distribution and interface matching, thereby reducing the operating voltage and increasing luminous brightness.

Description

Technical Field

[0001] This invention relates to the technical field of light-emitting diodes, and more particularly to an LED epitaxial structure and its fabrication method. Background Technology

[0002] LED chips, as light-emitting semiconductor electronic components, are widely used in lighting, backlighting, and display applications due to their small size, high brightness, and low energy consumption. A typical LED epitaxial wafer includes a substrate and an epitaxial layer grown on the substrate.

[0003] With the widespread adoption of LED technology in the lighting field, the market and industry have placed higher demands on the luminous efficiency of LED chips. Generally speaking, improving luminous efficiency requires first reducing the operating voltage without sacrificing the brightness of the LED chip. Therefore, further reducing the operating voltage while maintaining or even increasing brightness has become a key technical challenge that needs to be overcome. However, the existing structural design of LED chips makes it difficult to achieve this goal. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multi-LED epitaxial structure and its preparation method, which can significantly reduce the operating voltage and improve the luminous brightness.

[0005] To address the aforementioned technical problems, the first aspect of this invention provides an LED epitaxial structure, comprising a substrate, a buffer layer, a three-dimensional GaN layer, an undoped GaN layer, an N-type semiconductor layer, a stress-relieving layer, a multi-quantum-well light-emitting layer, an electron-blocking layer, and a P-type semiconductor layer, sequentially stacked; wherein... The multi-quantum-well light-emitting layer has a periodic structure, and each period of the multi-quantum-well light-emitting layer includes a quantum well layer and a quantum barrier layer stacked sequentially, wherein the quantum well layer is an InGaN layer; Along the growth direction, the proportion of In component in the quantum well layer in the last period is less than the proportion of In component in the quantum well layer in any other period.

[0006] As an improvement to the above scheme, the number of periods of the multi-quantum-well light-emitting layer is n, where n = 2-16. The proportion of In component in the quantum well layer in the first period is X1, and the proportion of In component in the quantum well layer in the last period is X. n X n = (0-0.8)X1.

[0007] As an improvement to the above scheme, X n = (0.3-0.5)X1.

[0008] As an improvement to the above scheme, in the final period, the proportion of In component in the quantum well layer remains unchanged along the growth direction.

[0009] As an improvement to the above scheme, from the first cycle to the (n-1)th cycle, the proportion of In component in the InGaN layer remains unchanged as the number of cycles increases.

[0010] As an improvement to the above scheme, in the first to (n-1)th cycles, the proportion of In component in the InGaN layer is 0.1-0.3.

[0011] As an improvement to the above scheme, the thickness of the quantum well layer is 2nm-4nm in each cycle; The thickness of the quantum barrier layer is 8nm-12nm; the quantum barrier layer is a GaN layer.

[0012] As an improvement to the above scheme, the stress relief layer has a periodic structure with 2-6 cycles, and each cycle of the stress relief layer includes InGaN layers and GaN layers stacked sequentially. The InGaN layer has an In content of 0.03-0.1% and a thickness of 1nm-3nm; the GaN layer has a thickness of 6nm-12nm.

[0013] As an improvement to the above scheme, the electron blocking layer has a periodic structure with 2-12 periods; each period of the electron blocking layer includes AlGaN layers and GaN layers stacked sequentially. The Al component in the AlGaN layer accounts for 0.1-0.3% of the total content. The thickness of the electron blocking layer is 10nm-60nm.

[0014] A second aspect of the present invention provides a method for preparing the aforementioned LED epitaxial structure, comprising the following steps: Provide a substrate; A buffer layer is sequentially grown on the substrate; A three-dimensional GaN layer is grown on the buffer layer; An undoped GaN layer is grown on the three-dimensional GaN layer; An N-type semiconductor layer is grown on the undoped GaN layer; A stress-relief layer is grown on the N-type semiconductor layer; A multi-quantum-well light-emitting layer is grown on the stress-relieving layer; An electron blocking layer is grown on the multi-quantum-well light-emitting layer; A P-type semiconductor layer is grown on the electron blocking layer; The multi-quantum-well light-emitting layer has a periodic structure, and each period of the multi-quantum-well light-emitting layer includes a quantum well layer and a quantum barrier layer stacked sequentially, wherein the quantum well layer is an InGaN layer; Along the growth direction, the proportion of In component in the quantum well layer in the last period is less than the proportion of In component in the quantum well layer in any other period.

[0015] Implementing this invention has the following beneficial effects: In this invention, by reducing the proportion of In component in the quantum well layer in the last period of the multi-quantum-well emitting layer, the quantum confinement Stark effect can be weakened, the hole injection balance can be improved, and the carrier distribution and interface matching can be optimized, thereby reducing the operating voltage and increasing the luminous brightness. Attached Figure Description

[0016] Figure 1 : A schematic diagram of an LED epitaxial structure in this invention; Figure 2 : Schematic diagram of the structure of the multi-quantum well light-emitting layer in this invention.

[0017] Figure label: 100 - Substrate; 200 - Buffer layer; 300 - Three-dimensional GaN layer; 400 - Undoped GaN layer; 500 - N-type semiconductor layer; 600 - Stress relief layer; 700 - Multi-quantum well light-emitting layer; 710 - Quantum well layer; 720 - Quantum barrier layer; 800 - Electron blocking layer; 900 - P-type semiconductor layer. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described in further detail below.

[0019] In the description of this application, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "inner", and "outer" are based on the orientation or positional relationship shown in the accompanying drawings. They are intended only to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the components referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0020] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. The range defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range.

[0021] To address the above problems, the first aspect of this invention provides an LED epitaxial structure, please refer to [link / reference]. Figure 1It includes a substrate 100, a buffer layer 200, a three-dimensional GaN layer 300, an undoped GaN layer 400, an N-type semiconductor layer 500, a stress relief layer 600, a multi-quantum-well light-emitting layer 700, an electron-blocking layer 800, and a P-type semiconductor layer 900, which are stacked sequentially; (See also...) Figure 2 The multi-quantum-well light-emitting layer 700 has a periodic structure. Each period of the multi-quantum-well light-emitting layer 700 includes a quantum well layer 710 and a quantum barrier layer 720 stacked sequentially. The quantum well layer 710 is an InGaN layer. Along the growth direction, the proportion of In component in the quantum well layer 710 in the last period is less than the proportion of In component in the quantum well layer 710 in any other period.

[0022] Due to the effect of polarization electric field accumulation, the band tilt angle of the multi-quantum well light-emitting layer 700 near the last period of the P-type semiconductor layer 900 reaches 15°-20°, which is much higher than that of the preceding well layer. Electrons are forced to be localized at the bottom of the well, while holes are repelled to the barrier layer interface. The spatial separation distance between the two exceeds 10nm, the wave function overlap integral drops to <1%, and the radiative recombination rate decays sharply. Therefore, the multi-quantum well light-emitting layer 700 near the last period of the P-type semiconductor layer 900 hardly emits light, but it has a significant impact on the operating voltage of the LED chip.

[0023] In this invention, by reducing the proportion of In composition in the quantum well layer 710 in the last period of the multi-quantum well light-emitting layer 700, the quantum confinement Stark effect (QCSE) can be weakened and the hole injection balance can be improved. At the same time, the carrier distribution and interface matching can be optimized, thereby reducing the operating voltage and increasing the luminous brightness.

[0024] Furthermore, the number of periods of the multi-quantum-well light-emitting layer 700 is n, the proportion of In component in the quantum well layer 710 in the first period is X1, and the proportion of In component in the quantum well layer 710 in the last period is X. n X n = (0-0.8)X1, that is, compared to X1, X n This reduces the in content by 20%-100%. Higher inin content leads to more severe lattice mismatch in InGaN / GaN, resulting in enhanced piezoelectric polarization, band bending, and electron-hole wavefunction separation. In this application, X is modulated... n= (0-0.8)X1, which can significantly reduce the built-in electric field strength in this region, thereby suppressing QCSE, reducing the loss of radiative recombination efficiency, and reducing the band shift between it and the P-type layer, forming a smoother hole injection channel, reducing the hole injection barrier, lowering the operating voltage, and facilitating preferential hole injection and distribution into the deeper quantum well layer 710, achieving uniform carrier distribution among multiple wells, promoting synergistic luminescence of multiple quantum well layers 710, and further improving the overall luminescence intensity. It is understood that the In component ratio in the quantum well layer 710 in the final period can also be 0. For example, X n =0、X n =0.1X1、X n =0.2X1、X n =0.6X1、X n =0.7X1、X n =0.8X1, but not limited to this.

[0025] Better, X n = (0.3-0.5)X1, where the In composition is sufficient to significantly alleviate QCSE while maintaining the effective light-emitting capability of the quantum well in the last period. If the In composition in the last period is too high, strong band bending may still exist in the last period, the improvement in electron-hole recombination efficiency will be limited, and hole injection will still be concentrated in the first few quantum well layers 710, resulting in no significant improvement in luminous brightness and operating voltage. If the In composition in the last period is too low, a GaN-like structure layer will be formed, the band gap will widen, and it will be unable to effectively capture charge carriers, losing its light-emitting function. It may also cause defects at the interface between the last period and the other quantum well layers 710, affecting the reliability of the LED chip. For example, X n =0.3X1、X n =0.35X1, X n =0.4X1, X n =0.45X1, X n =0.5X1, but not limited to this.

[0026] In some specific and preferred embodiments, n = 2-16, and exemplary values ​​can be 2, 4, 6, 8, 10, 12, 14, 16, but are not limited thereto.

[0027] Preferably, in the final period, the proportion of In component in the quantum well layer 710 remains constant along the growth direction. Since the InGaN layer itself is relatively thin, the In component gradually decreases, and directly reducing the In component can more quickly weaken the quantum confinement Stark effect and improve luminous efficiency.

[0028] Furthermore, from the first period to the (n-1)th period, as the number of periods increases, the proportion of In component in the InGaN layer remains unchanged. The same In component in each period can ensure the consistency of the emission wavelength, which helps to obtain a higher peak intensity.

[0029] Understandably, the In composition in the quantum well layer 710 can be adjusted according to the emission color requirements, and the In composition ratio is generally 0.1-0.3. Specifically, when the LED epitaxial structure is a blue LED, the In composition ratio is 0.1-0.2 in the first to (n-1)th cycles; when the LED epitaxial structure is a green LED, the In composition ratio is 0.2-0.3 in the first to (n-1)th cycles.

[0030] Preferably, in each cycle, the thickness of the quantum well layer 710 is 2nm-4nm, and exemplary values ​​can be 2nm, 2.5nm, 3nm, 3.5nm, or 4nm, but are not limited thereto. The quantum barrier layer 720 is a GaN layer, and the thickness of the quantum barrier layer 720 is 8nm-12nm, and exemplary values ​​can be 8nm, 9nm, 10nm, 11nm, or 12nm, but are not limited thereto.

[0031] Preferably, the stress relief layer 600 has a periodic structure, and each period of the stress relief layer 600 includes InGaN layers and GaN layers stacked sequentially, with a period number of 2-6. A controllable tensile stress or compensating stress is pre-introduced below the multi-quantum well light-emitting layer 700 to partially offset the compressive stress generated during the subsequent growth of the multi-quantum well light-emitting layer 700, making the energy band in the quantum well flatter, thereby improving the radiative recombination efficiency, reducing the penetration dislocation density, and improving the crystal quality.

[0032] The InGaN layer has an In content of 0.03-0.1% and a thickness of 1nm-3nm; the GaN layer has a thickness of 6nm-12nm.

[0033] Preferably, the electron blocking layer 800 has a periodic structure with 2-12 periods; each period of the electron blocking layer 800 includes sequentially stacked AlGaN and GaN layers, which can form a higher effective barrier, significantly suppress electron overflow, reduce non-radiative recombination, and significantly reduce the activation energy of holes, improve hole injection efficiency, and reduce the operating voltage of the LED device. The Al composition in the AlGaN layer accounts for 0.1-0.3%.

[0034] Furthermore, the thickness of the electron blocking layer 800 is 10nm-60nm, and can be, for example, 10nm, 20nm, 30nm, 40nm, 50nm, or 60nm, but is not limited thereto.

[0035] In some specific and preferred embodiments, the thickness of the AlGaN layer in the electron blocking layer 800 is 1nm-10nm, and the thickness of the GaN layer is 1nm-10nm.

[0036] Accordingly, a second aspect of the present invention provides a method for preparing the LED epitaxial structure, comprising the following steps: (1) Provide a substrate 100; (2) A buffer layer 200 is sequentially grown on the substrate 100; (3) A three-dimensional GaN layer 300 is grown on the buffer layer 200; (4) An undoped GaN layer 400 is grown on the three-dimensional GaN layer 300; (5) An N-type semiconductor layer 500 is grown on the undoped GaN layer 400; (6) A stress relief layer 600 is grown on the N-type semiconductor layer 500; (7) A multi-quantum-well light-emitting layer 700 is grown on the stress-relieving layer 600; (8) An electron blocking layer 800 is grown on the multi-quantum-well light-emitting layer 700; (9) A P-type semiconductor layer 900 is grown on the electron blocking layer 800; The multi-quantum-well light-emitting layer 700 has a periodic structure. Each period of the multi-quantum-well light-emitting layer 700 includes a quantum well layer 710 and a quantum barrier layer 720 stacked sequentially. The quantum well layer 710 is an InGaN layer. Along the growth direction, the proportion of In component in the quantum well layer 710 in the last period is less than the proportion of In component in the quantum well layer 710 in any other period.

[0037] Preferably, in step (1), the substrate 100 may include a sapphire substrate, a silicon carbide substrate or a silicon substrate; more preferably, the substrate 100 is a sapphire substrate.

[0038] Preferably, in step (2), the buffer layer 200 can be a GaN layer, and the growth thickness of the buffer layer 200 is 15nm-35nm.

[0039] Preferably, in step (3), the growth thickness of the three-dimensional GaN layer 300 is 500nm-2000nm.

[0040] Furthermore, the growth temperature of the three-dimensional GaN layer 300 is 1000℃-2000℃, and the growth pressure is 100 torr-300 torr. Specifically, the temperature of the reaction chamber is adjusted to 1000℃-2000℃, the pressure is 100 torr-300 torr, a MO source (metal-organic source) is introduced, and N2, H2, and NH3 are introduced, wherein NH3 is used as the reaction gas, and N2 and H2 are used as carrier gases, to grow a three-dimensional GaN layer 300 of a predetermined thickness.

[0041] Preferably, in step (4), the growth thickness of the undoped GaN layer 400 is 800nm-1200nm.

[0042] Preferably, in step (5), the N-type semiconductor layer 500 has a growth thickness of 1000nm-3000nm, which can provide electrons.

[0043] Preferably, in step (9), the P-type semiconductor layer 900 can be a P-type doped GaN layer, and the growth thickness of the P-type semiconductor layer 900 is 5nm-100nm, which can provide holes.

[0044] It is understood that the buffer layer 200, the undoped GaN layer 400, the N-type semiconductor layer 500, the stress relief layer 600, the multi-quantum-well light-emitting layer 700, the electron blocking layer 800, and the P-type semiconductor layer 900 are all grown using existing processes and materials, and will not be further described in this invention.

[0045] The present invention will be further described below with reference to specific embodiments: Example 1 This embodiment provides an LED epitaxial structure, comprising a substrate, a buffer layer, a three-dimensional GaN layer, an undoped GaN layer, an N-type semiconductor layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer, which are sequentially stacked. The multi-quantum-well emitting layer has a periodic structure with 10 periods. Each period of the multi-quantum-well emitting layer consists of sequentially stacked quantum well layers and quantum barrier layers. The quantum well layers are InGaN layers. The In composition percentage is 0.15 in the first to ninth periods (X1=0.15); in the tenth period, the In composition percentage decreases by 10%, i.e., X... 10 =0.9X1; the quantum barrier layer is a GaN layer.

[0046] The stress relief layer has a periodic structure with 3 periods. Each period of the stress relief layer includes InGaN layer and GaN layer stacked sequentially. The InGaN layer has an In content of 0.05% and a thickness of 2nm. The GaN layer has a thickness of 10nm. The electron blocking layer has a periodic structure with 5 periods. Each period of the electron blocking layer includes AlGaN and GaN layers stacked sequentially. The Al content in the AlGaN layer is 0.2%. The thickness of the AlGaN layer is 4 nm and the thickness of the GaN layer is 3 nm.

[0047] Accordingly, this embodiment also provides a method for fabricating an LED epitaxial structure, including the following steps: (1) Provide a substrate; (2) Buffer layers are grown sequentially on the substrate; (3) A three-dimensional GaN layer is grown on the buffer layer; (4) Growing undoped GaN layers on three-dimensional GaN layers; (5) An N-type semiconductor layer is grown on an undoped GaN layer; (6) A stress-relieving layer is grown on the N-type semiconductor layer; (7) A multi-quantum-well light-emitting layer is grown on the stress-relieving layer; (8) An electron blocking layer is grown on the multi-quantum-well light-emitting layer; (9) Grow a P-type semiconductor layer on the electron blocking layer.

[0048] Example 2 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreases by 20%, i.e., X 10 =0.8X1.

[0049] Example 3 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreases by 30%, i.e., X 10 =0.7X1.

[0050] Example 4 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreases by 40%, i.e., X 10 =0.6X1.

[0051] Example 5 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreases by 50%, i.e., X 10 =0.5X1.

[0052] Example 6 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreases by 60%, i.e., X 10 =0.4X1.

[0053] Example 7 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreases by 70%, i.e., X 10 =0.3X1.

[0054] Example 8 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreases by 80%, i.e., X 10 =0.2X1.

[0055] Example 9 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreased by 90%, i.e., X 10 =0.1X1.

[0056] Example 10 This embodiment provides an LED epitaxial structure, which is basically the same as that in Embodiment 1, except that: The proportion of In component in the 10th cycle decreases by 100%, i.e., X 10 =0, the quantum well layer in the 10th period is a GaN layer.

[0057] Comparative Example 1 This comparative example provides an LED epitaxial structure that is basically the same as that in Example 1, except that: The multi-quantum-well light-emitting layer has a periodic structure with 10 periods. Each period of the multi-quantum-well light-emitting layer includes sequentially stacked quantum well layers and quantum barrier layers. The quantum well layers are InGaN layers with an In composition ratio of 0.15; the quantum barrier layers are GaN layers.

[0058] Performance testing The LED epitaxial structures obtained in the examples and comparative examples were fabricated into 10mil×24mil chips using the same chip process conditions. 300 LED chips were selected from each example and tested at a current of 120mA. The operating voltage, luminous brightness and luminous efficiency of the obtained chips were tested, and the luminous efficiency was calculated based on Comparative Example 1.

[0059] The specific test results are shown in Table 1.

[0060] Table 1. Test results of the examples and comparative examples

[0061] The results above show that by reducing the proportion of In component in the last period of the multi-quantum-well emitting layer, the quantum confinement Stark effect can be weakened and the hole injection balance can be improved. At the same time, the carrier distribution and interface matching can be optimized, thereby reducing the operating voltage and increasing the luminous brightness.

[0062] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. An LED epitaxial structure, characterized in that, It includes a substrate, a buffer layer, a three-dimensional GaN layer, an undoped GaN layer, an N-type semiconductor layer, a stress-relieving layer, a multiple quantum well light-emitting layer, an electron-blocking layer, and a P-type semiconductor layer, which are stacked sequentially; among them, The multi-quantum-well light-emitting layer has a periodic structure, and each period of the multi-quantum-well light-emitting layer includes a quantum well layer and a quantum barrier layer stacked sequentially, wherein the quantum well layer is an InGaN layer; Along the growth direction, the proportion of In component in the quantum well layer in the last period is less than the proportion of In component in the quantum well layer in any other period.

2. The LED epitaxial structure as described in claim 1, characterized in that, The number of periods of the multi-quantum-well light-emitting layer is n, where n = 2-16. The proportion of In component in the quantum well layer in the first period is X1, and the proportion of In component in the quantum well layer in the last period is X. n X n = (0-0.8)X1.

3. The LED epitaxial structure as described in claim 2, characterized in that, X n = (0.3-0.5) X1.

4. The LED epitaxial structure as described in claim 1, characterized in that, In the final period, the proportion of In component in the quantum well layer remains constant along the growth direction.

5. The LED epitaxial structure according to any one of claims 2-4, characterized in that, From the first cycle to the (n-1)th cycle, the proportion of In component in the InGaN layer remains constant as the number of cycles increases.

6. The LED epitaxial structure as described in claim 5, characterized in that, In the first to the (n-1)th cycle, the proportion of In component in the InGaN layer is 0.1-0.

3.

7. The LED epitaxial structure as described in claim 1, characterized in that, In each cycle, the thickness of the quantum well layer is 2nm-4nm; The thickness of the quantum barrier layer is 8nm-12nm; the quantum barrier layer is a GaN layer.

8. The LED epitaxial structure as described in claim 1, characterized in that, The stress relief layer has a periodic structure with 2-6 periods. Each period of the stress relief layer includes InGaN layers and GaN layers stacked sequentially. The InGaN layer has an In content of 0.03-0.1% and a thickness of 1nm-3nm; the GaN layer has a thickness of 6nm-12nm.

9. The LED epitaxial structure as described in claim 1, characterized in that, The electron blocking layer has a periodic structure with 2-12 periods; each period of the electron blocking layer includes AlGaN layers and GaN layers stacked sequentially. The Al component in the AlGaN layer accounts for 0.1-0.3% of the total content. The thickness of the electron blocking layer is 10nm-60nm.

10. A method for preparing an LED epitaxial structure as described in any one of claims 1-9, characterized in that, Includes the following steps: Provide a substrate; A buffer layer is sequentially grown on the substrate; A three-dimensional GaN layer is grown on the buffer layer; An undoped GaN layer is grown on the three-dimensional GaN layer; An N-type semiconductor layer is grown on the undoped GaN layer; A stress-relief layer is grown on the N-type semiconductor layer; A multi-quantum-well light-emitting layer is grown on the stress-relieving layer; An electron blocking layer is grown on the multi-quantum-well light-emitting layer; A P-type semiconductor layer is grown on the electron blocking layer; The multi-quantum-well light-emitting layer has a periodic structure, and each period of the multi-quantum-well light-emitting layer includes a quantum well layer and a quantum barrier layer stacked sequentially, wherein the quantum well layer is an InGaN layer; Along the growth direction, the proportion of In component in the quantum well layer in the last period is less than the proportion of In component in the quantum well layer in any other period.

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