Algan / algan multiple quantum well based led structure with band tailoring for improving light emitting efficiency and preparation method thereof

Abstract

The application relates to an AlGaN / AlGaN multi-quantum well base LED structure with band tailoring for improving light emitting efficiency and a preparation method thereof, and belongs to the microelectronic technical field. z Ga 1‑z N layer, a pulse type AlGaN / Al y Ga 1‑y N multi-quantum well active region, a p-type AlGaN layer and a P-type GaN cap layer; each well layer of the multi-quantum well active region contains a plurality of in-well potential barriers Al a Ga 1‑a N with a certain thickness, wherein 0 The application can not only inhibit the spatial separation of carriers to reduce the quantum confinement Stark effect under low excitation, but also not intensify the carrier leakage under high excitation due to the weakening or disappearance of the in-well potential barrier effect, so that the light emitting efficiency of the ultraviolet LED is improved.

Description

Technical Field

[0001] This invention relates to an AlGaN / AlGaN multi-quantum-well LED structure with improved luminous efficiency through bandgap trimming and its fabrication method, belonging to the field of microelectronics technology. Background Technology

[0002] Because ultraviolet AlGaN-based LEDs have broad potential applications in air and water sterilization and purification, gas sensing, 3D printing, ultraviolet lithography, and biomedicine, and possess advantages such as small size, portability, durability, and adjustable bandgap, they have attracted significant attention from researchers. By changing the Al composition, the emission wavelength of AlGaN-based multiple quantum well (MQW) structures can cover the ultraviolet band from approximately 200 nm to 360 nm. However, for high-Al-content AlGaN-based deep ultraviolet (DUV) LEDs, the highest reported external quantum efficiency (EQE) is only 20.3%, far lower than that of mature InGaN-based blue LEDs (>80%). One significant reason for its low EQE is its low internal quantum efficiency (IQE). This stems from the spontaneous polarization of the AlGaN material itself and the piezoelectric polarization induced by well / barrier lattice mismatch, leading to spatial separation of electron and hole wave functions in MQWs and reducing radiative recombination efficiency—a phenomenon known as the quantum confinement Stark effect (QCSE). Additionally, it involves numerous defects caused by substrate-epitaxy layer lattice mismatch and difficulties in p-type doping. To address the low IQE, researchers have made various attempts. Some groups have proposed reducing the well width to mitigate the impact of QCSE and thus improve IQE. However, this method exacerbates the LED efficiency droop problem caused by electron leakage under high current injection. Summary of the Invention

[0003] To address the problems existing in the background technology, the present invention provides an AlGaN / AlGaN multi-quantum-well-based LED structure and its fabrication method that improve luminous efficiency by utilizing bandgap trimming. The present invention can not only suppress the spatial separation of charge carriers under low excitation, thereby reducing the quantum confinement Stark effect (QCSE), but also, under high excitation, the effect of the potential barrier in the well is weakened or disappears, thus not aggravating the leakage of charge carriers, thereby improving the luminous efficiency of ultraviolet LEDs.

[0004] The present invention adopts the following technical solution:

[0005] An AlGaN / AlGaN multi-quantum-well LED structure that utilizes bandgap trimming to improve luminous efficiency comprises, from bottom to top, a sapphire substrate, an AlN buffer layer, and an n-type Al... z Ga 1-z N-layer, pulsed AlGaN(well) / Aly Ga 1-y N(barrier) multi-quantum well active region, p-type AlGaN layer and p-type GaN capping layer;

[0006] The pulsed AlGaN(well) / Al y Ga 1-y The N(barrier) multi-quantum-well active region includes several cycles of pulsed AlGaN(well) / Al y Ga 1-y N-barrier quantum wells, each quantum well containing several AlGaN well layers with a certain thickness (0.5-4 nm) of internal barrier Al a Ga 1-a N, causing the AlGaN well layer to form similar to n Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure, similar to "Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x The pulse structure is N…, where 0 < n < 10, 0 < x < z < 1, and 0 < x < a < y ≤ 1.

[0007] A method for fabricating the AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency through bandgap trimming, comprising the following steps:

[0008] (1) An AlN buffer layer and an n-type Al2O3 layer are sequentially grown on a sapphire substrate. z Ga 1-z N layers;

[0009] (2) In n-type Al z Ga 1-z Pulsed AlGaN (well) / Al layers with several cycles grown on the N-layer y Ga 1-y N(barrier) multi-quantum-well active region, i.e., in n-type Al z Ga 1-z Several cycles of pulsed AlGaN (well) / Al are grown on the N-layer. y Ga 1-y N (barrier) quantum wells, each quantum well containing an AlGaN well layer with several Al atoms. x Ga 1-x N / Al a Ga 1-a N / Al x Ga1-x N-pulse structure;

[0010] (3) In pulsed AlGaN(well) / Al y Ga 1-y An LED structure is obtained by sequentially growing a p-type AlGaN layer and a p-type GaN capping layer on the N(barrier) multi-quantum well active region.

[0011] Preferably, in step (2), when pulsed AlGaN(well) / Al y Ga 1-y The N(barrier) quantum well contains only one Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x For N-pulse structures, one cycle of pulsed AlGaN(well) / Al is grown. y Ga 1-y The process of N(barrier) quantum well is as follows:

[0012] A. Growth has an Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x The N-pulse structure well layer, the steps include:

[0013] ①The first part of the growth pulse structure Al x Ga 1-x N-well layer: Trimethylgallium and trimethylaluminum are introduced at 900℃~1300℃, with trimethylgallium and trimethylaluminum introduction rates of 8 sccm and 17 sccm, respectively, to grow Al. x Ga 1-x N-well layer;

[0014] ②The second part of the growth pulse structure Al a Ga 1-a N-structure: Trimethylgallium and trimethylaluminum are introduced at 900℃~1300℃, while Al is grown with a reduced trimethylgallium flow rate compared to step ①. a Ga 1-a With the N-structure, the flow rate of trimethylaluminum remains unchanged, satisfying the condition: 0 < x < a < 1;

[0015] ③ The third part of the growth pulse structure, Al x Ga 1-x N-well layer: Growth conditions are the same as in step ①;

[0016] B. Growth Al y Ga1-y N-layer.

[0017] Preferably, when the growth contains multiple Al cycles x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure of pulsed AlGaN(well) / Al y Ga 1-y In the case of N (barrier) quantum wells, the growth process of the well layer involves repeating steps ①, ②, ③, ②, ③, ②, ③… until a well layer with a predetermined period is obtained, and then Al is grown. y Ga 1-y N-layer.

[0018] Preferably, in step A, the growth thickness of the well layer is 2-5 nm; in step B, Al... y Ga 1-y The growth thickness of the N-barrier layer is 8-15 nm.

[0019] Preferably, pulsed AlGaN(trap) / Al y Ga 1-y The period of an N(barrier) quantum well is 3 to 15, preferably 5 at 1000°C. Too many periods will lead to poor crystal quality in the later stage of growth, while too few periods will lead to a weakening of the confinement effect of the active region.

[0020] Preferably, in step (2), each pulse structure is evenly spaced and arranged at equal intervals, and the number of pulse structures is 0 ≤ n < 10.

[0021] A uniformly spaced pulse structure improves luminous efficiency more than a random arrangement. Furthermore, excessive Al... x Ga 1- x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structures lead to more complex manufacturing processes, and an excessive number of them will occupy more of the light-emitting volume.

[0022] Preferably, step (1) consists of the following steps:

[0023] First, place the c-side sapphire substrate in a hydrogen atmosphere at 1000-1200℃ for 3-10 minutes, and then grow sequentially on the c-side sapphire substrate;

[0024] First, a 10-50 nm low-temperature AlN layer is grown at 550-950℃, followed by a 1-4 μm high-temperature AlN layer grown at 1000-1300℃. The low-temperature-then-high-temperature growth method can reduce the dislocation density originating from the substrate, thereby improving the structural quality of the subsequent epitaxial layer.

[0025] Then, a 1-4 μm layer of n-type Al was grown at 900-1200℃. z Ga 1-z An N-layer structure, where 0 < x < z < 1, with silicon as the n-type dopant source and a doping concentration of 3 * 10⁻⁶. 18 / cm 3 ;

[0026] Further preferred method involves first treating the c-side sapphire substrate in a hydrogen atmosphere at 1080°C for 6 minutes.

[0027] Then, a 10-50 nm low-temperature AlN layer is grown at 600℃, followed by a 1-4 μm high-temperature AlN layer at 1200℃, and finally a 1 μm AlN layer is grown at 1000℃. z Ga 1-z The N-layer has an n-type dopant source of silane.

[0028] Preferably, the specific steps of step (3) are as follows:

[0029] First, a 20-100 nm p-type AlGaN layer is grown at 900-1200℃, with magnesium as the p-type dopant source and a doping concentration of 3*10. 19 / cm 3 ;

[0030] Then, a p-type GaN capping layer with a thickness of 150-400 nm is grown at 900-1200℃, with magnesium as the p-type doping source and a doping concentration of 8*10⁻⁶. 19 / cm 3 .

[0031] Preferably, in step (3), a 30nm p-type AlGaN layer is first grown at 1000℃, and the p-type doping source is magnesia-dicenocene.

[0032] Then, a 200 nm thick p-type GaN capping layer was grown at 950 °C.

[0033] For any details not covered in this invention, please refer to the prior art.

[0034] The beneficial effects of this invention are as follows:

[0035] The main advantage of this invention is that it can reduce QCSE even without reducing the well width (especially under weak excitation conditions), as detailed below:Figure 2 For the quantum well structure band diagram without considering QCSE, Figure 3 This is the energy band diagram of the quantum well structure considering QCSE. It can be observed that under the influence of QCSE, electrons and holes undergo significant spatial separation, thus leading to a decrease in their luminous efficiency. Some have proposed reducing the quantum well width to mitigate the effect of QCSE, but this is not conducive to overcoming the problem of LED efficiency drooping under high current injection. The present invention, a pulsed AlGaN(well) / Al... y Ga 1-y N(barrier) multi-quantum-well structure (see) Figure 4 , Figure 5 Al inside its trap layer x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x The N-pulse structure design allows for reduced electron-hole spatial separation without decreasing the well width, while the in-well barrier Al with adjustable thickness and composition a is also possible. a Ga 1-a N ensures that under high excitation, the effect of the potential barrier inside the well is weakened or eliminated, thus preventing the leakage of charge carriers and improving the luminous efficiency of ultraviolet LEDs. Attached Figure Description

[0036] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0037] Figure 1 This is a schematic diagram of the structure of the AlGaN / AlGaN multi-quantum-well LED of the present invention.

[0038] Figure 2 This is the band structure diagram of the quantum well without considering QCSE.

[0039] Figure 3 The energy band diagram of the quantum well structure considering QCSE.

[0040] Figure 4 As designed in this invention, each AlGaN well layer contains only one Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x A schematic diagram of the band structure of the N-pulse structure.

[0041] Figure 5As designed in this invention, each AlGaN well layer contains only 2 Al atoms. x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x A schematic diagram of the band structure of the N-pulse structure.

[0042] Figures 2-5 In the diagram, all solid dots represent electrons, and all hollow dots represent holes. Figure 4 , 5 The columnar protrusions refer to the potential barrier Al inside the well. a Ga 1-a N;

[0043] In the figure, 1 is the sapphire substrate, 2 is the AlN buffer layer, and 3 is the n-type AlN layer. z Ga 1-z N-layer, 4-layer pulsed AlGaN (well) / Al y Ga 1-y N (barrier) multi-quantum well active region, 5, p-type AlGaN layer, 6, p-type GaN capping layer. Detailed implementation method:

[0044] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. However, this is not the only description; all aspects not described in detail herein are based on conventional techniques in the field.

[0045] Example 1

[0046] An AlGaN / AlGaN multi-quantum-well-based LED structure that utilizes bandgap trimming to improve luminous efficiency, such as Figure 1 As shown, the growth sequence from bottom to top includes: sapphire substrate 1, AlN buffer layer 2, n-type Al z Ga 1-z N-layer 3, Pulsed AlGaN (well) / Al y Ga 1-y 4. N(barrier) multi-quantum well active region, 5. p-type AlGaN layer and 6. P-type GaN capping layer;

[0047] Pulsed AlGaN(trap) / Al y Ga 1-y The N(barrier) multi-quantum-well active region 4 includes several cycles of pulsed AlGaN(well) / Al y Ga 1-y N-barrier quantum wells, each quantum well containing several AlGaN well layers with a certain thickness (0.5-4 nm) of internal barrier Ala Ga 1-a N, causing the AlGaN well layer to form similar to n Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure, similar to "Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x The pulse structure is N…, where 0 < n < 10, 0 < x < z < 1, and 0 < x < a < y ≤ 1.

[0048] Example 2

[0049] A method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure that utilizes bandgap trimming to improve luminous efficiency includes the following steps:

[0050] (1) An AlN buffer layer 2 and an n-type Al2O3 layer are sequentially grown on a sapphire substrate 1. z Ga 1-z N layers 3;

[0051] (2) In n-type Al z Ga 1-z Pulsed AlGaN (well) / Al layers were grown on layer N3 for several cycles. y Ga 1-y N(barrier) multi-quantum well active 4-region, i.e., in n-type Al z Ga 1-z Several cycles of pulsed AlGaN (well) / Al are grown on the N-layer. y Ga 1-y N (barrier) quantum wells, each quantum well containing an AlGaN well layer with several Al atoms. x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure;

[0052] Among them, when each pulsed quantum well layer contains only 1 Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x When using an N-pulse structure, a pulsed AlGaN(well) / Al structure is grown over one cycle. y Ga1-y N(barrier) quantum well (e.g.) Figure 4 The process is as follows:

[0053] A. Growth has an Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x The N-pulse structure well layer includes:

[0054] ①The first part of the growth pulse structure Al x Ga 1-x N-well layer: Al is grown by introducing trimethylgallium and trimethylaluminum at 900℃~1300℃. x Ga 1-x N-well layer;

[0055] ②The second part of the growth pulse structure Al a Ga 1-a N-structure: Trimethylgallium and trimethylaluminum are introduced at 900℃~1300℃, while Al is grown with a reduced trimethylgallium flow rate compared to step ①. a Ga 1-a With the N-structure, the flow rate of trimethylaluminum remains unchanged, satisfying the condition: 0 < x < a < 1;

[0056] ③The third part of the growth pulse structure Al x Ga 1-x N-well layer: The conditions are the same as in step ①;

[0057] like Figure 4 As shown, each pulsed AlGaN(well) / Al y Ga 1-y The AlGaN well layer of the N(barrier) quantum well all includes one Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure;

[0058] B. Growth Al y Ga 1-y N-layer.

[0059] (3) In pulsed AlGaN(well) / Al y Ga 1-y A p-type AlGaN layer 5 and a p-type GaN capping layer 6 are sequentially grown on the N(barrier) multi-quantum well active region to obtain an LED structure.

[0060] In this invention, the bandgap engineering is mainly reflected in the design of each pulsed AlGaN quantum well. This invention designs several Al... x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure. For example... Figure 4 , Figure 5 As shown, examples with 1 or 2 Al are demonstrated respectively. x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure of pulsed AlGaN(well) / Al y Ga 1-y N(barrier) quantum well structure.

[0061] Example 3

[0062] A method for fabricating an AlGaN / AlGaN multi-quantum-well LED structure with improved luminous efficiency by utilizing bandgap trimming is described in Example 2, except that in step (2), each pulsed AlGaN (well) / Al y Ga 1-y The AlGaN well layers of N(barrier) quantum wells all contain two Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure. For example... Figure 5 As shown.

[0063] Example 4

[0064] A method for fabricating an AlGaN / AlGaN multi-quantum-well LED structure that improves luminous efficiency by utilizing bandgap trimming is described in Example 2. The difference is that in step (2), each pulse structure is arranged at equal and uniform intervals. The equidistant and uniform arrangement of the pulse structures can improve the luminous efficiency more than the random arrangement.

[0065] In step A, the growth thickness of the well layer is 2-5 nm. In step B, Al... y Ga 1-y The growth thickness of the N-barrier layer is 8-15 nm.

[0066] Pulsed AlGaN(well) / Al at 1000℃ y Ga 1-yThe N(barrier) quantum well has 5 periods; too many periods will lead to poor crystal quality in the later growth stage, while too few periods will weaken the confinement effect of the active region.

[0067] Example 5

[0068] A method for fabricating an AlGaN / AlGaN multi-quantum-well LED structure with improved luminous efficiency by utilizing bandgap trimming, as described in Example 4, except that step (1) specifically involves the following steps:

[0069] First, the c-side sapphire substrate is treated in a hydrogen atmosphere at 1080℃ for 6 minutes, and then growth is performed sequentially on the c-side sapphire substrate. This method can effectively remove oxides on the substrate surface and improve the growth quality of the sample.

[0070] A 25nm low-temperature AlN layer is first grown at 600℃, followed by a 1μm high-temperature AlN layer at 1200℃. This low-temperature-then-high-temperature growth method can reduce the dislocation density originating from the substrate, thereby improving the structural quality of the subsequent epitaxial layer. This method can grow a high-quality AlN buffer layer, laying the foundation for growing a high-quality LED structure.

[0071] Then, a 1 μm layer of n-type Al was grown at 1000℃. z Ga 1-z An N-layer structure, where 0 < x < z < 1, with an n-type dopant source of silane and a doping concentration of 3 * 10⁻⁶. 18 / cm 3 .

[0072] Example 6

[0073] A method for fabricating an AlGaN / AlGaN multi-quantum-well LED structure with improved luminous efficiency by utilizing bandgap trimming, as described in Example 5, except that the specific steps of step (3) are as follows:

[0074] First, a 30 nm p-type AlGaN layer is grown at 1000℃. The p-type doping source is magnesia-diocene, and the doping concentration is 3*10⁵. 19 / cm 3 ;

[0075] Then, a 200 nm thick p-type GaN capping layer 6 was grown at 950 °C, with magnesium as the p-type dopant source and a doping concentration of 8*10⁻⁶. 19 / cm 3 .

[0076] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An AlGaN / AlGaN multi-quantum-well-based LED structure that utilizes bandgap trimming to improve luminous efficiency, characterized in that, The growth sequence from bottom to top includes: sapphire substrate, AlN buffer layer, n-type Al... z Ga 1-z N-layer, pulsed AlGaN / Al y Ga 1-y N quantum well active regions, p-type AlGaN layers and p-type GaN capping layers; The pulsed AlGaN / Al y Ga 1-y The multiple quantum well active regions include several cycles of pulsed AlGaN / Al y Ga 1-y N quantum wells, each with an AlGaN well layer containing several Al atoms with a certain thickness within the well. a Ga 1-a N, causing the AlGaN well layer to form similar to n Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x The N-pulse structure is defined as follows: 0 < n < 10, 0 < x < z < 1, and 0 < x < a < y ≤ 1.

2. A method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by bandgap trimming as described in claim 1, characterized in that, Includes the following steps: (1) An AlN buffer layer and an n-type Al2O3 layer are sequentially grown on a sapphire substrate. z Ga 1-z N layers; (2) In n-type Al z Ga 1-z Pulsed AlGaN / Al grown on the N layer for several cycles y Ga 1-y N quantum well active regions, i.e., in n-type Al z Ga 1-z Several cycles of pulsed AlGaN / Al were grown on the N-layer. y Ga 1-y N quantum wells, each of which contains an AlGaN well layer containing several Al atoms. x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure; (3) In pulsed AlGaN / Al y Ga 1-y An LED structure is obtained by sequentially growing p-type AlGaN layers and p-type GaN capping layers on the active regions of multiple quantum wells.

3. The method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by utilizing bandgap trimming as described in claim 2, characterized in that, In step (2), when pulsed AlGaN / Al y Ga 1-y The N quantum well contains only one Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x When using an N-pulse structure, a pulsed AlGaN / Al structure is grown over one cycle. y Ga 1-y The process of N-quantum wells is as follows: A. Growth has an Al x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x The N-pulse structure well layer, the steps include: ①The first part of the growth pulse structure Al x Ga 1-x N-well layer: Al is grown by introducing trimethylgallium and trimethylaluminum at 900℃~1300℃. x Ga 1-x N-well layer; ②The second part of the growth pulse structure Al a Ga 1-a N-structure: Trimethylgallium and trimethylaluminum are introduced at 900℃~1300℃, while Al is grown with a reduced trimethylgallium flow rate compared to step ①. a Ga 1-a The N-structure is configured to satisfy the condition: 0 < x < a < 1; ③ The third part of the growth pulse structure, Al x Ga 1-x N-well layer: Growth conditions are the same as in step ①; B. Growth Al y Ga 1-y N-layer.

4. The method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by utilizing bandgap trimming according to claim 3, characterized in that, When growth contains multiple Al cycles x Ga 1-x N / Al a Ga 1-a N / Al x Ga 1-x N-pulse structure of pulsed AlGaN / Al y Ga 1-y For N quantum wells, the growth process of the well layer involves repeating steps ①, ②, ③, ②, ③, ②, ③… until a well layer with a predetermined period is obtained, and then Al is grown. y Ga 1-y N-layer.

5. The method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by utilizing bandgap trimming according to claim 4, characterized in that, In step A, the growth thickness of the well layer is 2-5 nm. In step B, Al... y Ga 1-y The growth thickness of the N-barrier layer is 8-15 nm.

6. The method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by utilizing bandgap trimming according to claim 5, characterized in that, Pulsed AlGaN / Al y Ga 1-y The period of an N-quantum well is 3 to 15, preferably 5 at 1000°C.

7. The method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by utilizing bandgap trimming according to claim 6, characterized in that, In step (2), each pulse structure is arranged at equal and uniform intervals.

8. The method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by utilizing bandgap trimming according to claim 2, characterized in that, Step (1) The specific steps are as follows: First, place the c-side sapphire substrate in a hydrogen atmosphere at 1000-1200℃ for 3-10 minutes, and then grow sequentially on the c-side sapphire substrate; First, a 10-50 nm low-temperature AlN layer is grown at 550-950℃, followed by a 1-4 μm high-temperature AlN layer grown at 1000-1300℃. Then, a 1-4 μm layer of n-type Al was grown at 900-1200℃. z Ga 1-z An N-layer structure, where 0 < x < z < 1, with silicon as the n-type dopant source and a doping concentration of 3 * 10⁻⁶. 18 / cm 3 ; Further preferred method involves first treating the c-side sapphire substrate in a hydrogen atmosphere at 1080°C for 6 minutes. Then, a 10-50 nm low-temperature AlN layer is grown at 600℃, followed by a 1-4 μm high-temperature AlN layer at 1200℃, and finally a 1 μm AlN layer is grown at 1000℃. z Ga 1-z The N-layer has an n-type dopant source of silane.

9. The method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by utilizing bandgap trimming according to claim 2, characterized in that, The specific steps of step (3) are as follows: First, a 20-100 nm p-type AlGaN layer is grown at 900-1200℃, with magnesium as the p-type dopant source and a doping concentration of 3*10. 19 / cm 3 ; Then, a p-type GaN capping layer with a thickness of 150-400 nm is grown at 900-1200℃, with magnesium as the p-type doping source and a doping concentration of 8*10⁻⁶. 19 / cm 3 .

10. The method for fabricating an AlGaN / AlGaN multi-quantum-well-based LED structure with improved luminous efficiency by utilizing bandgap trimming according to claim 9, characterized in that, In step (3), a 30nm p-type AlGaN layer is first grown at 1000℃, and the p-type doping source is magnesia-dicenocene. Then, a 200 nm thick p-type GaN capping layer was grown at 950 °C.

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