An LED epitaxial structure with an Al component inclined N-type graded electron blocking layer and a preparation method thereof

Abstract

The application discloses a GaN-based LED epitaxial structure with an Al component inclined N type graded electron blocking layer and a preparation method thereof, and belongs to the technical field of semiconductor optoelectronic devices. The epitaxial structure comprises, from bottom to top, a substrate, a buffer layer, an n-type semiconductor layer, a multi-quantum well active region, an Al component inclined N type graded AlGaN electron blocking layer, a p-type semiconductor layer and a p-type semiconductor contact layer. The Al component inclined N type graded AlGaN electron blocking layer can effectively inhibit electron leakage and improve hole injection efficiency, so that the light emitting performance of the LED is improved. The preparation method of the epitaxial structure is simple, low in cost and suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor optoelectronic device technology, specifically relating to a device with an Al composition tilt. N LED epitaxial structure with a gradient electron blocking layer and its preparation method. Background Technology

[0002] Light-emitting diodes (LEDs) made from III-V group semiconductor materials possess significant advantages such as high efficiency, energy saving, environmental friendliness, and long lifespan, and have been widely used in general lighting, displays, signal lights, and optical communications. However, GaN-based LEDs exhibit a sharp drop in efficiency under high current density driving, meaning that the external quantum efficiency of the device decreases significantly with increasing injection current. One of the main reasons for this efficiency drop is carrier leakage. Because the electron mobility in GaN material is much higher than that of holes, after electrons are injected from the n-type region into the multi-quantum-well active region, some electrons will cross the final quantum barrier layer into the p-type region and undergo non-radiative recombination with holes, thus significantly reducing the luminous efficiency of the LED. In addition, band tilt caused by polarization effects also exacerbates electron leakage. To suppress electron leakage, a p-AlGaN electron blocking layer with a large bandgap is usually inserted between the multi-quantum-well active region and the p-type hole injection layer. However, this conventional p-AlGaN layer, while blocking electron overflow, also hinders the effective injection of holes from the p-type region into the active region. Therefore, developing novel electron blocking layer structures that can suppress electron leakage while improving hole injection efficiency is key to enhancing the optoelectronic performance of GaN-based LED devices. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the present invention provides a method with an Al component tilted... N The LED epitaxial structure with a gradient electron blocking layer and its fabrication method can effectively suppress electron leakage, promote hole injection, and improve the photoelectric performance of LEDs.

[0004] According to one aspect of the present invention, a method is provided that has an Al component tilted N The LED epitaxial structure with a gradient electron blocking layer, from bottom to top, includes a substrate, a buffer layer, an n-type semiconductor layer, a multi-quantum-well active region, and an Al composition tilting layer. N The structure comprises a graded AlGaN electron blocking layer, a p-type semiconductor layer, and a p-type semiconductor contact layer; characterized in that: the Al composition is tilted. NThe gradient AlGaN electron blocking layer includes a first electron blocking layer, a second electron blocking layer, and a third electron blocking layer; the Al composition of the first electron blocking layer gradually increases from bottom to top, the Al composition of the second electron blocking layer gradually decreases from bottom to top, and the Al composition of the third electron blocking layer gradually increases from bottom to top; the average Al composition of the first electron blocking layer is not lower than the average Al composition of the third electron blocking layer; the thicknesses of the first electron blocking layer, the second electron blocking layer, and the third electron blocking layer are not exactly equal.

[0005] Optionally, the Al component of the first electron blocking layer is derived from... x 1 increases linearly to x 2. The Al composition of the second electron blocking layer from x 2 linearly decreasing to x 3. The Al composition of the third electron blocking layer from x 3 increases linearly to x 4, of which, x 1. x 2. x 3. x 4. The following conditions must be met: 0 < x 1< x 2<1, 0< x 3< x 4<1, x 3< x 2, x 4+ x 3≤ x 2+ x 1.

[0006] Optionally, x 1. x 2. x 3. x 4 also satisfies the following condition: 0 < x 3≤ x 1< x 2<1, 0< x 3< x 4≤ x 2 < 1.

[0007] Optionally, x 1. x 2. x 3. x 4 also satisfies the following condition: 0 < x 1< x 3< x 4< x 2 < 1.

[0008] Optionally, x 1. x 2.x 3. x 4 also satisfies the following condition: 0 < x 3< x 1< x 2< x 4<1.

[0009] Optionally, among the first electron blocking layer, the second electron blocking layer, and the third electron blocking layer, there is an electron blocking layer with the largest thickness, the thickness of which is 0.6 to 5 times the sum of the thicknesses of the other two electron blocking layers.

[0010] Optionally, the Al component is tilted. N The thickness of the gradient AlGaN electron blocking layer is 5~200 nm, and the average Al composition is 0.05~0.95.

[0011] Optionally, the Al component is tilted. N The hole concentration of the gradient AlGaN electron blocking layer is 10. 16 -10 19 cm -3 .

[0012] According to another aspect of the invention, the above-mentioned tilted Al component is provided. N A method for fabricating an LED epitaxial structure with a gradient electron blocking layer, characterized by comprising the following steps: A buffer layer is formed on the substrate; An n-type semiconductor layer is formed on the buffer layer; An active region is formed on the n-type semiconductor layer; Al composition tilting is formed in the active region. N Gradient AlGaN electron blocking layer; tilted in Al component N A p-type semiconductor layer is formed on a gradient AlGaN electron blocking layer; A p-type semiconductor contact layer is formed on the p-type semiconductor layer.

[0013] Optionally, the Al component is tilted. N The growth temperature of the gradient AlGaN electron blocking layer is 700℃-1300℃, and the pressure is 10-600 Torr. The composition of Al is controlled by adjusting the flow rates of the Al source and Ga source, and the doping concentration is controlled by adjusting the flow rate of the magnesium source.

[0014] As can be seen from the above technical solution, the beneficial effects of the present invention are as follows: 1. The present invention provides a tilted Al component. NThe LED epitaxial structure with a gradient electron blocking layer has an Al composition that first gradually increases, then gradually decreases, and finally gradually increases again, forming a tilted shape. N This structure not only reduces the polarization electric field in the active region, weakens the quantum confinement Stark effect, and increases the overlap rate of the spatial wave functions of electrons and holes, but also adjusts the band structure near the electron blocking layer. This increases the effective electron barrier height while decreasing the effective hole barrier height, thereby effectively suppressing electron leakage and improving hole injection efficiency. Therefore, the solution of this invention improves the radiative recombination efficiency, internal quantum efficiency, and light output power of LEDs.

[0015] 2. The present invention provides a tilted Al component. N The LED epitaxial structure with a gradient electron blocking layer can reduce crystal defects caused by lattice mismatch between different material layers and improve the luminous efficiency of the device by using a gradient design of the Al composition of the electron blocking layer.

[0016] 3. The present invention provides a tilted Al component. N The method for fabricating LED epitaxial structures with gradient electron blocking layers is simple to operate, has good repeatability, low cost, and is easy to implement. Attached Figure Description

[0017] To more clearly illustrate the structure of the present invention, a detailed description is provided below in conjunction with the accompanying drawings (the drawings are only schematic diagrams of the structure and do not represent actual dimensions to scale): Figure 1 shows an embodiment of the present invention with an Al component tilt. N A schematic diagram of the LED epitaxial structure with a gradient electron blocking layer.

[0018] Figure 2 shows the tilt of the Al component provided in the embodiment of the present invention. N A schematic diagram of the structure of a gradient AlGaN electron blocking layer.

[0019] Figure 3 shows an Al component tilting method provided in an embodiment of the present invention. N A schematic diagram of the Al composition distribution in a gradient AlGaN electron blocking layer.

[0020] Figure 4 shows another Al component tilt provided in an embodiment of the present invention. N A schematic diagram of the Al composition distribution in a gradient AlGaN electron blocking layer.

[0021] Figure 5 shows another Al component tilt provided in an embodiment of the present invention. N A schematic diagram of the Al composition distribution in a gradient AlGaN electron blocking layer.

[0022] Figure 6 shows another Al component tilt provided in an embodiment of the present invention.N A schematic diagram of the Al composition distribution in a gradient AlGaN electron blocking layer.

[0023] Figure 7 shows another Al component tilt provided in an embodiment of the present invention. N A schematic diagram of the Al composition distribution in a gradient AlGaN electron blocking layer.

[0024] Figure 8 shows an embodiment of the present invention with an Al component tilt. N A comparison of the output light power of an LED with a gradient electron blocking layer and that of a conventional LED.

[0025] Figure label: 1 - Sapphire substrate, 2 - Buffer layer, 3 - n-type semiconductor layer, 4 - Active region, 5 - Al composition tilt N The structure consists of a gradient AlGaN electron blocking layer, a 6-p semiconductor layer, a 7-p semiconductor contact layer, an 8-n electrode, a 9-p electrode, a 51-first electron blocking layer, a 52-second electron blocking layer, and a 53-third electron blocking layer. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0027] like Figure 1 As shown, this is an embodiment of the invention with an Al component tilted. N A schematic diagram of an LED epitaxial structure with a gradient electron blocking layer, comprising, along the epitaxial growth direction: a substrate 1; a buffer layer 2 on the substrate 1; an n-type semiconductor layer 3 on the buffer layer 2; an active region 4 on the n-type semiconductor layer 3; and an Al composition tilting layer on the active region 4. N Type-gradient AlGaN electron blocking layer 5; located at the Al composition tilt N A p-type semiconductor layer 6 on a gradient AlGaN electron blocking layer 5; a p-type semiconductor contact layer 7 on the p-type semiconductor layer 6; an n-type electrode 8 on the n-type semiconductor layer 3; and a p-type electrode 9 on the p-type semiconductor contact layer 7.

[0028] Substrate 1 is selected from any one of sapphire substrate, GaN, SiC, Si, GaAs, and glass.

[0029] The buffer layer 2 is selected from one or more of AlN, AlGaN, and GaN.

[0030] The doping concentration of Si in the n-type semiconductor layer 3 is 5×10 16 cm -3 ~5×10 19 cm -3 . For example, the doping concentration is 5×10 16 cm -3 , 3×10 17 cm -3 , 8×10 17 cm -3 , 2×10 18 cm -3 , 5×10 18 cm -3 , 1×10 19 cm -3 , 5×10 19 cm -3 . The n-type semiconductor layer is selected from n-GaN and n-AlGaN layers.

[0031] The active region 4 can be composed of multiple periods of Al y1 Ga 1-y1 N quantum well layers and Al y2 Ga 1-y2 N quantum barrier layers stacked alternately, where 0.5 < y1 < y2 < 1, and the LED emits ultraviolet light. For example, 0.5 < y1 < 0.6, 0.6 < y2 < 0.7, and the LED emits ultraviolet light. The active region 4 can also be composed of multiple periods of InGaN quantum well layers and GaN quantum barrier layers stacked alternately. Depending on the In composition in the InGaN quantum wells, the LED can emit blue, green, or red light.

[0032] Al composition gradient N type graded AlGaN electron blocking layer 5 has a structure as Figure 2 shown, along the epitaxial growth direction, successively including: the first electron blocking layer 51, the second electron blocking layer 52, and the third electron blocking layer 53.

[0033] The Al composition of the first electron blocking layer 51 gradually increases successively along the epitaxial growth direction, the Al composition of the second electron blocking layer 52 gradually decreases successively along the epitaxial growth direction, and the Al composition of the third electron blocking layer 53 gradually increases successively along the epitaxial growth direction; the average Al composition of the first electron blocking layer is not lower than the average Al composition of the third electron blocking layer.

[0034] As Figures 3-7 shown, the thickness of the first electron blocking layer 51 is d 1, and the Al composition along the growth direction ranges from x1 increases linearly to x 2. The thickness of the second electron blocking layer 52 is d 2- d 1. The Al component grows along the direction from... x 2 linearly decreasing to x 3. The thickness of the third electron blocking layer is d 3- d 2. The Al component grows along the direction from... x 3 increases linearly to x 4, of which, x 1. x 2. x 3. x 4. The following conditions must be met: 0 < x 1< x 2<1, 0< x 3< x 4<1, x 3< x 2, x 4+ x 3≤ x 2+ x 1. In x 4+ x 3= x 2+ x At time 1, the average Al composition of the first electron blocking layer 51 is equal to the average Al composition of the third electron blocking layer 53. x 4+ x 3< x 2+ x At time 1, the average Al composition of the first electron blocking layer 51 is greater than the average Al composition of the third electron blocking layer 53.

[0035] In some embodiments, the Al component is tilted. N Al composition distribution of type graded AlGaN electron blocking layer 5 x 1. x 2. x 3. x 4 also satisfies the following condition: 0 < x 3< x 1< x 2<1, 0< x 3< x 4< x 2<1, x 4+ x 3< x 2+ x 1; x 1 and x The relationship between 4 can be as follows: Figure 3 The following conditions are met. x 1< x4, or it can be like this Figure 4 As shown x 1> x 4, it can also be x 1= x 4. In this case, the average Al composition of the first electron blocking layer is higher than that of the third electron blocking layer.

[0036] In some embodiments, the Al component is tilted. N The Al composition distribution of the gradient AlGaN electron blocking layer 5 is as follows: Figure 5 As shown, the x 1. x 2. x 3. x 4 also satisfies the following condition: 0 < x 3= x 1< x 2<1, 0< x 3< x 4< x 2<1, x 4+ x 3< x 2+ x 1. In this case, the average Al composition of the first electron blocking layer is higher than that of the third electron blocking layer.

[0037] In some embodiments, the Al component is tilted. N Al composition distribution of type graded AlGaN electron blocking layer 5 x 1. x 2. x 3. x 4 also satisfies the following condition: 0 < x 3< x 1< x 4= x If 2 < 1, then x 4+ x 3< x 2+ x 1. In this case, the average Al composition of the first electron blocking layer is higher than that of the third electron blocking layer.

[0038] In some embodiments, the Al component is tilted. N Al composition distribution of type graded AlGaN electron blocking layer 5 x 1. x 2. x 3. x 4 also satisfies the following condition: 0 < x 3= x 1< x 4= x If 2 < 1, then x4+ x 3= x 2+ x 1. In this case, the average Al composition of the first electron blocking layer is equal to the average Al composition of the third electron blocking layer.

[0039] In some embodiments, the Al component is tilted. N The Al composition distribution of the gradient AlGaN electron blocking layer 5 is as follows: Figure 6 As shown, the x 1. x 2. x 3. x 4 also satisfies the following condition: 0 < x 1< x 3< x 4< x 2<1, x 4+ x 3≤ x 2+ x 1.

[0040] In some embodiments, the Al component is tilted. N The Al composition distribution of the gradient AlGaN electron blocking layer 5 is as follows: Figure 7 As shown, the x 1. x 2. x 3. x 4 also satisfies the following condition: 0 < x 3< x 1< x 2< x 4<1, x 4+ x 3≤ x 2+ x 1.

[0041] The AlGaN electron blocking layer with the above-mentioned Al composition distribution can not only effectively reduce the polarization electric field in the active region and increase the overlap rate of the electron-hole wave function in the quantum well, but also effectively suppress electron leakage and improve hole injection efficiency by adjusting the band structure, thereby increasing the concentration of electrons and holes in the quantum well and ultimately improving the photoelectric performance of LEDs.

[0042] The thicknesses of the first electron blocking layer 51, the second electron blocking layer 52, and the third electron blocking layer 53 are not exactly equal. In some embodiments, two of the thicknesses of the first electron blocking layer 51, the second electron blocking layer 52, and the third electron blocking layer 53 may be unequal, with the thickness of the third electron blocking layer being equal to the thickness of the smaller one. For example, as... Figure 3 As shown, the thickness of the second electron blocking layer 52 is ( d 2-d 1) Thickness greater than that of the first electron blocking layer 51 d 1. Thickness of the first electron blocking layer 51 d 1 equals the thickness of the third electron blocking layer 53 ( d 3- d 2) For example, d 1 is 5 nm. d 2- d 1 is 10 nm. d 3- d 2 is 5 nm. For example, the thickness of the first electron blocking layer 51 is greater than the thickness of the second electron blocking layer 52, and the thickness of the second electron blocking layer 52 is equal to the thickness of the third electron blocking layer 53. For example, as... Figure 4 As shown, the thickness of the third electron blocking layer 53 is greater than the thickness of the first electron blocking layer 51, and the thickness of the first electron blocking layer 51 is equal to the thickness of the second electron blocking layer 52. In other embodiments, the thicknesses of the first electron blocking layer 51, the second electron blocking layer 52, and the third electron blocking layer 53 may all be unequal. For example, as... Figure 5 As shown, the thickness of the second electron blocking layer 52 is greater than the thickness of the first electron blocking layer 51, and the thickness of the first electron blocking layer 51 is greater than the thickness of the third electron blocking layer 53; for example, d 1 is 10 nm. d 2- d 1 is 20nm. d 3- d 2 is 6 nm. For example, as... Figure 6 As shown, the thickness of the first electron blocking layer 51 is greater than the thickness of the second electron blocking layer 52, and the thickness of the second electron blocking layer 52 is greater than the thickness of the third electron blocking layer 53; for example, d 1 is 50 nm. d 2- d 1 is 30nm. d 3- d 2 is 25 nm. For example, the thickness of the first electron blocking layer 51 is 15 nm, the thickness of the second electron blocking layer 52 is 10 nm, and the thickness of the third electron blocking layer 53 is 20 nm.

[0043] Among the first electron blocking layer 51, the second electron blocking layer 52, and the third electron blocking layer 53, there is an electron blocking layer with the largest thickness. The thickness of this electron blocking layer with the largest thickness is 0.6 to 5 times, preferably 0.6, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5 times, the sum of the thicknesses of the other two electron blocking layers. For example, the thickness of the first electron blocking layer 51 is 10 nm, the thickness of the second electron blocking layer 52 is 50 nm, and the thickness of the third electron blocking layer 53 is 10 nm. Another example is that the thickness of the first electron blocking layer 51 is 10 nm, the thickness of the second electron blocking layer 52 is 20 nm, and the thickness of the third electron blocking layer 53 is 5 nm. This structural design is beneficial to suppressing electron leakage, promoting hole injection, and improving the optoelectronic performance of the device.

[0044] Al composition gradient N The thickness of the Al composition gradient type AlGaN electron blocking layer 5 is 5 to 200 nm. For example, the thickness is 5, 10, 20, 30, 40, 50, 60, 80, 100, 120, 150, 180, 200 nm. Here, the thickness refers to the total thickness of the first electron blocking layer 51, the second electron blocking layer 52, and the third electron blocking layer 53.

[0045] Al composition gradient N The average Al composition of the Al composition gradient type AlGaN electron blocking layer 5 is 0.05 to 0.95. The average Al compositions of the first electron blocking layer 51, the second electron blocking layer 52, and the third electron blocking layer 53 are all in the range of 0.05 to 0.95, and the total average Al composition of the three electron blocking layers is also in the range of 0.05 to 0.95; for example x 1 = 0.7, x 2 = 0.8, x 3 = 0.6, x 4 = 0.7, the thickness of the first electron blocking layer 51 is 5 nm, the thickness of the second electron blocking layer 52 is 10 nm, and the thickness of the third electron blocking layer 53 is 5 nm. Due to the linear change of the Al composition, the average Al composition of the first electron blocking layer 51 is 0.75, the average Al composition of the second electron blocking layer 52 is 0.7, and the average Al composition of the third electron blocking layer 53 is 0.65, Al composition gradient N The average Al composition of the Al composition gradient type AlGaN electron blocking layer 5 is 0.7. Using Al y1 Ga 1-y1 N / Al y2 Ga 1-y2 N multiple quantum wells (0.5 < y1 < y2 < 1) as the active region, Al composition gradient NThe average Al composition of the graded AlGaN electron blocking layer 5 of the p-type is 0.45 to 0.95. When an InGaN / GaN multi-quantum well active region is adopted, the Al composition is inclined. N The average Al composition of the graded AlGaN electron blocking layer 5 of the p-type is 0.05 to 0.65.

[0046] Al composition inclination N The hole concentration of the graded AlGaN electron blocking layer 5 of the p-type is 10 16 -10 19 cm -3 ; The hole concentrations of the first electron blocking layer 51, the second electron blocking layer 52 and the third electron blocking layer 53 are all 10 16 -10 19 cm -3 . The hole concentrations of the first electron blocking layer 51, the second electron blocking layer 52 and the third electron blocking layer 53 may be equal or may not be equal.

[0047] The p-type semiconductor layer is selected from p-GaN, p-AlGaN, p-AlInGaN.

[0048] The p-type semiconductor contact layer 7 can be p-GaN or other semiconductor materials.

[0049] The n electrode layer 8 is a Ti / Al / Ni / Au alloy structure, the p electrode layer 9 is a Ni / Au alloy structure, and the n electrode layer 8 and the p electrode layer 9 can also be composed of other materials.

[0050] Figure 8 Shown is a comparison chart of the light output power of an LED with a graded electron blocking layer with an Al composition inclination according to an embodiment of the present invention and the light output power of an LED with a conventional structure. The active region of the LED structure is composed of multiple periods of Al N Ga y1 Ga 1-y1 N quantum well layers and Al y2 Ga 1-y2 N quantum barrier layers are alternately stacked, where 0.5 < y1 < 0.6 and 0.6 < y2 < 0.7. The p-AlGaN electron blocking layer of the conventional structure adopts a single Al composition. Al composition inclination N Al composition distribution of the graded AlGaN electron blocking x 1, x 2, x 3, x 4 satisfy the following conditions: 0.4 < x 3 < x 1 < x 2 < 1, 0.4 < x 3 < x 4 < x2<1, x 4+ x 3< x 2+ x 1; The thickness of the second electron blocking layer is greater than the thickness of the first electron blocking layer, and the thickness of the first electron blocking layer is equal to the thickness of the third electron blocking layer. The thickness of the electron blocking layers and the average Al composition are the same in both structures. From Figure 8 As can be seen, at an injection current density of 100 A / cm 2 At that time, the AL component was tilted. N The LED light output power of the gradient AlGaN electron blocking layer is 24 W / cm². 2 Compared to conventional LED structures, the light output power is increased by 34%.

[0051] The embodiments of the present invention also provide the above-mentioned tilted Al component. N The fabrication method of LED epitaxial structure with gradient electron blocking layer, combined with Figure 1 and Figure 2 The explanation includes the following steps: S1: A buffer layer 2 is formed on substrate 1; S2: An n-type semiconductor layer 3 is formed on the buffer layer 2; S3: An active region 4 is formed on the n-type semiconductor layer 3; S4: Al composition tilting is formed on active region 4. N Gradient AlGaN electron blocking layer 5; S5: Inclined on Al component N A p-type semiconductor layer 6 is formed on a gradient AlGaN electron blocking layer 5; S6: A p-type semiconductor contact layer 7 is formed on the p-type semiconductor layer 6.

[0052] Furthermore, the Al component is tilted. N The growth temperature of the gradient AlGaN electron blocking layer is 700℃-1300℃, and the pressure is 10-600 Torr. The doping concentration is controlled by adjusting the flow rate of the magnesium source (Cp2Mg), and the composition of Al is controlled by adjusting the flow rates of the Al source (TMA) and Ga source (TMG). The first electron blocking layer 51, the second electron blocking layer 52, and the third electron blocking layer 53 are grown sequentially.

[0053] Furthermore, a surface is etched onto the surface of the n-type semiconductor layer 3 to expose a portion of the n-type semiconductor layer 3. Then, an n-type electrode 8 is fabricated on the n-type semiconductor layer 3 and a p-type electrode 9 is fabricated on the p-type semiconductor contact layer 7.

[0054] The present invention provides a tilted Al component NA method for fabricating an LED epitaxial structure with an n-type gradient electron blocking layer, wherein the n-type semiconductor layer, the active region, and the Al composition are tilted. N The p-type gradient AlGaN electron blocking layer, p-type semiconductor layer, and p-type semiconductor contact layer are grown using MOCVD or MBE processes. The fabrication process is simple, reproducible, and low-cost, making it suitable for industrial production.

[0055] The above description is only used to illustrate the present invention and is not intended to limit the implementation method of the present invention in any way. Therefore, any modifications or alterations made to the present invention based on the shape, structure, features and basic ideas described herein should fall within the scope of intellectual property rights intended to be protected by the present invention.

Claims

1. A type of aluminum component tilted N The LED epitaxial structure with a gradient electron blocking layer, from bottom to top, includes a substrate, a buffer layer, an n-type semiconductor layer, a multi-quantum-well active region, and an Al composition tilting layer. N The structure comprises a graded AlGaN electron blocking layer, a p-type semiconductor layer, and a p-type semiconductor contact layer; characterized in that: The Al component is tilted N The gradient AlGaN electron blocking layer includes a first electron blocking layer, a second electron blocking layer, and a third electron blocking layer; the Al composition of the first electron blocking layer gradually increases from bottom to top, the Al composition of the second electron blocking layer gradually decreases from bottom to top, and the Al composition of the third electron blocking layer gradually increases from bottom to top. The average Al composition of the first electron blocking layer is not lower than the average Al composition of the third electron blocking layer; the thicknesses of the first electron blocking layer, the second electron blocking layer, and the third electron blocking layer are not completely equal.

2. The Al component tilting according to claim 1 N The LED epitaxial structure with a gradient electron blocking layer is characterized by: The Al component of the first electron blocking layer from x 1 increases linearly to x 2. The Al component of the second electron blocking layer from x 2 linearly decreasing to x 3, the Al component of the third electron blocking layer from x 3 increases linearly to x 4, the aforementioned x 1. x 2. x 3. x 4. The following conditions must be met: 0 < x 1< x 2<1, 0< x 3< x 4<1, x 3< x 2, x 4+ x 3≤ x 2+ x 1.

3. The Al component tilting according to claim 2 N The LED epitaxial structure with a gradient electron blocking layer is characterized by: The x 1. x 2. x 3. x 4. It also meets the following conditions: x 3≤ x 1, x 4≤ x 2.

4. The Al component tilting according to claim 2 N The LED epitaxial structure with a gradient electron blocking layer is characterized by: The x 1. x 2. x 3. x 4. It also meets the following conditions: x 1< x 3, x 4< x 2.

5. The Al component tilting method according to claim 2 N The LED epitaxial structure with a gradient electron blocking layer is characterized by: The x 1. x 2. x 3. x 4. It also meets the following conditions: x 3< x 1, x 2< x 4.

6. The Al component tilting according to claim 1 N The LED epitaxial structure with a gradient electron blocking layer is characterized by: Among the first electron blocking layer, the second electron blocking layer, and the third electron blocking layer, there is an electron blocking layer with the largest thickness, the thickness of which is 0.6 to 5 times the sum of the thicknesses of the other two electron blocking layers.

7. The Al component tilting according to claim 1 N The LED epitaxial structure with a gradient electron blocking layer is characterized by: The Al component is tilted N The thickness of the gradient AlGaN electron blocking layer is 5~200 nm, and the average Al composition is 0.05~0.

95.

8. The Al component tilting according to claim 1 N The LED epitaxial structure with a gradient electron blocking layer is characterized by: The Al component is tilted N The hole concentration of the gradient AlGaN electron blocking layer is 10. 16 -10 19 cm -3 .

9. The Al component tilting as described in any one of claims 1-8 N The method for fabricating an LED epitaxial structure with a gradient electron blocking layer is characterized by, Includes the following steps: A buffer layer is formed on the substrate; An n-type semiconductor layer is formed on the buffer layer; An active region is formed on the n-type semiconductor layer; Al component tilt is formed on the active region. N Gradient AlGaN electron blocking layer; The Al component is tilted N A p-type semiconductor layer is formed on a gradient AlGaN electron blocking layer; A p-type semiconductor contact layer is formed on the p-type semiconductor layer.

10. The Al component tilting according to claim 9 N The method for fabricating an LED epitaxial structure with a gradient electron blocking layer is characterized by: The Al component is tilted N The growth temperature of the gradient AlGaN electron blocking layer is 700℃-1300℃, and the pressure is 10-600 Torr. The composition of Al is controlled by adjusting the flow rates of the Al source and Ga source, and the doping concentration is controlled by adjusting the flow rate of the magnesium source.

Images