Gallium nitride-based light emitting diode epitaxial structure and preparation method

Abstract

The application provides a gallium nitride-based light-emitting diode epitaxial structure and a preparation method, and relates to the technical field of semiconductor devices, and comprises a substrate, an AlN nucleation layer arranged on the substrate, a plurality of pores contained in the nucleation layer to form a light scattering structure, a N-type GaN layer arranged on the AlN nucleation layer in sequence, an active layer containing an indium component gradient quantum well, and an electron blocking layer and a P-type GaN layer. An edge termination layer is arranged on the lateral edge of the P-type GaN layer, the layer is gradiently doped with N ions, a gradually changed charge distribution is formed to smooth the edge electric field. The application significantly improves the light output efficiency through the light scattering structure and the optimized active layer design, and greatly improves the reverse breakdown voltage and working reliability of the device through the innovative edge termination layer structure.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and more specifically, to a gallium nitride-based light-emitting diode epitaxial structure and its fabrication method. Background Technology

[0002] Gallium nitride-based light-emitting diodes (GaN-based LEDs) are semiconductor light-emitting devices that use gallium nitride (GaN) material as their core. They are widely used in displays, lighting, and laser lighting. GaN material has a wide bandgap, high electron mobility, and good thermal stability, enabling it to emit high-brightness blue, green, and ultraviolet light. With continuous technological advancements, GaN-based LEDs are gradually surpassing other semiconductor materials in terms of luminous efficacy, high-temperature resistance, and high-voltage applications, making them an important choice for high-performance light sources.

[0003] Current gallium nitride (GaN)-based LEDs, due to their high refractive index, typically experience total internal reflection within the device, resulting in a significant amount of light failing to be effectively extracted. While some designs have employed surface roughening or other light-scattering structures to improve light extraction efficiency, these methods still fall short in certain situations. Furthermore, current GaN-based LEDs often exhibit electric field spikes at the device's edge regions under high voltages, particularly with unoptimized edge-termination designs. This can lead to premature breakdown and reduced voltage withstand capability. Such electric field congestion usually requires additional design optimization to mitigate, but many existing designs still cannot effectively address this issue. Summary of the Invention

[0004] The present invention provides an epitaxial structure and fabrication method for a gallium nitride-based light-emitting diode, which can solve the technical problems of total internal reflection of light in the device, resulting in a large amount of light that cannot be effectively extracted from the LED, and electric field spikes usually appearing in the edge region of the device under high voltage, especially when the edge termination design is not optimized, which can lead to premature breakdown.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a gallium nitride-based light-emitting diode epitaxial structure, comprising:

[0007] Substrate;

[0008] An AlN nucleation layer is disposed on the substrate, and the AlN nucleation layer has a plurality of pores for forming a light scattering structure;

[0009] An N-type GaN layer is disposed on the AlN nucleation layer;

[0010] An active layer is disposed on the N-type GaN layer, and the active layer includes multiple pairs of indium composition gradient sub-wells formed by alternating stacking of InGaN and GaN;

[0011] An electron blocking layer is disposed on the active layer;

[0012] A p-type GaN layer is disposed on the electron blocking layer;

[0013] An edge termination layer is disposed at the lateral edge of the P-type GaN layer. The edge termination layer has a concentration gradient of N-ion doping, which is such that the N-ion doping concentration on the side closer to the P-type GaN layer is greater than the N-ion doping concentration on the side farther away from the P-type GaN layer.

[0014] The electrodes form ohmic contacts with the N-type GaN layer and the P-type GaN layer, respectively.

[0015] In a second aspect, the present invention provides a method for preparing the gallium nitride-based light-emitting diode epitaxial structure described in the first aspect, comprising:

[0016] S1: Construct a simulation model of the epitaxial structure of a gallium nitride-based light-emitting diode;

[0017] S2: Using the simulation model, determine the reverse breakdown voltage of the gallium nitride-based light-emitting diode epitaxial structure under various structural parameters;

[0018] S3: Determine the optimal structural parameters of the gallium nitride-based light-emitting diode epitaxial structure based on the reverse breakdown voltage under various structural parameters;

[0019] S4: According to the optimal structural parameters, an AlN nucleation layer is deposited on the substrate by radio frequency sputtering;

[0020] S5: By selectively depositing argon ions into a portion of the region, multiple pores are generated on the AlN nucleation layer to form a light scattering structure.

[0021] S6: An N-type GaN layer is deposited on the AlN nucleation layer by chemical vapor deposition;

[0022] S7: By chemical vapor deposition, InGaN and GaN are alternately stacked and deposited on the N-type GaN layer to form an active layer with an indium composition gradient quantum well;

[0023] S8: An electron blocking layer is deposited on the active layer by chemical vapor deposition;

[0024] S9: A P-type GaN layer is deposited on the electron blocking layer by chemical vapor deposition;

[0025] S10: N ions are doped into the edge of the P-type GaN layer, and the N ion doping concentration on the side closer to the P-type GaN layer is greater than the N ion doping concentration on the side farther away from the P-type GaN layer, forming an edge termination layer with a gradually changing charge distribution.

[0026] S11: Connect electrodes on the N-type GaN layer and the P-type GaN layer.

[0027] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0028] (1) Multiple pores are set on the AlN nucleation layer to form a light scattering structure, which can effectively scatter and reflect light, increase the effective light emitted from the LED chip, and thus improve the overall brightness and efficiency of the LED.

[0029] (2) The active layer adopts an indium-component gradient quantum well design formed by alternating stacks of InGaN and GaN. This design can effectively reduce lattice mismatch and stress problems caused by excessive indium content, while improving carrier injection efficiency and enhancing light emission efficiency. Compared with traditional quantum well structures, the gradient quantum well design can provide higher luminous efficiency, especially in high-brightness applications.

[0030] (3) By doping the edge termination layer with nitrogen ions, the doping concentration is high on the side closer to the P-type GaN layer and low on the side farther away from the P-type GaN layer, forming a gradually changing charge distribution. This reduces electric field spikes and electric field congestion, optimizes the electric field distribution of the device, and avoids the electric field from concentrating at the edge of the device. This not only improves the breakdown voltage of the device, but also improves the withstand voltage performance of the device and extends its service life.

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, embodiments of the present invention are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of a gallium nitride-based light-emitting diode epitaxial structure provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the band structure variation of an indium-component gradient sub-well provided in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of an edge termination layer provided in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of an edge termination layer provided in an embodiment of the present invention, which illustrates one implementation of a partial compensation layer;

[0037] Figure 5 This is a schematic flowchart of a preparation method provided in an embodiment of the present invention.

[0038] Figure reference numerals: 1-Sapphire substrate; 2-AlN nucleation layer; 3-N-type GaN layer; 4-Active layer; 5-Electron blocking layer; 6-P-type GaN layer; 7-Edge termination layer; 71-Full compensation layer; 72-Partial compensation layer; 721-First region; 722-Second region; 723-Third region; 8-Electrode. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0040] Reference manual attached Figure 1 This invention provides a gallium nitride-based light-emitting diode epitaxial structure, comprising: a sapphire substrate 1, an AlN nucleation layer 2, an N-type GaN layer 3, an active layer 4, an electron blocking layer 5, a P-type GaN layer 6, an edge termination layer 7, and an electrode 8.

[0041] The sapphire substrate 1 forms the basis of the epitaxial structure. Serving as a growth platform for gallium nitride (GaN) thin films, it provides mechanical support and a starting point for crystal growth. Sapphire is commonly used for GaN epitaxial growth due to its excellent physical properties, such as good thermal conductivity and high transparency. However, due to the lattice mismatch between sapphire and GaN, certain growth techniques are required to improve the interface quality.

[0042] AlN nucleation layer 2 is disposed on sapphire substrate 1 as the bottom layer for GaN epitaxial growth. This layer helps to alleviate the lattice mismatch between sapphire and GaN. The introduction of the AlN layer helps to reduce the defect density of the GaN layer and improve the quality of the epitaxial layer. The AlN nucleation layer 2 has multiple pores, which form a light scattering structure, effectively enhancing light scattering and improving light extraction efficiency.

[0043] An N-type GaN layer 3 is disposed on the AlN nucleation layer 2, serving as the conductive layer for gallium nitride-based LEDs. By incorporating an appropriate amount of electron donor such as Si, the N-type GaN layer provides electron flow and supports efficient current injection into the active layer. The thickness and doping concentration of this layer are key factors in LED performance, affecting carrier injection efficiency and material conductivity.

[0044] An active layer 4 is disposed on the N-type GaN layer 3. The active layer 4 comprises multiple pairs of indium-concentrated gradient quantum wells formed by alternating stacks of InGaN and GaN. The indium-concentrated gradient quantum well is achieved by controlling the ratio of indium to gallium in the quantum well to gradually change the band gap. Different indium and gallium compositions can adjust the band gap of the quantum well, thereby affecting the emission wavelength of the light-emitting diode or laser. The gradually changing indium composition in the quantum well design can effectively reduce the stress caused by lattice mismatch and improve luminous efficiency.

[0045] Furthermore, the quantum well structure allows electrons and holes to combine in this region to form photons, thereby emitting light. The use of indium-gradient quantum well designs improves carrier injection efficiency, reduces stress caused by lattice mismatch, and simultaneously increases quantum efficiency. Gradient quantum wells can adjust the bandgap according to changes in indium concentration, enhancing the emission capability of light at different wavelengths, playing a particularly crucial role in blue and green LEDs.

[0046] An electron blocking layer 5 is disposed on the active layer 4. The main function of the electron blocking layer 5 is to prevent electrons from migrating into the p-type GaN layer, thereby enhancing the efficiency of the LED. By designing an appropriate band gap and doping concentration, this layer effectively controls the movement of charge carriers, ensuring that electrons only recombine within the active layer to generate photons, rather than being ineffectively carried away from the p-type GaN layer. This improves the light output efficiency of the LED.

[0047] A p-type GaN layer 6 is disposed on the electron blocking layer 5. By incorporating acceptor dopants such as Mg, a p-type conductive material is formed. The function of the p-type GaN layer is to provide holes, which recombine with electrons in the active layer to form photons, thereby achieving light emission. The doping concentration and quality of this layer directly affect the performance of the LED. The quality of the p-type GaN layer is generally difficult to control; therefore, its optimized design is crucial for improving the efficiency and stability of LEDs.

[0048] An edge-terminating layer 7 is disposed at the edge of the p-type GaN layer 6. By doping N ions into the edge-terminating layer 7, the N ion doping concentration is higher near the p-type GaN layer 6 than away, creating a gradually changing charge distribution. This design smooths the electric field distribution, preventing electric field concentration at the LED edge and mitigating the electric field congestion effect. Electric field congestion can lead to premature device breakdown; therefore, this design allows the LED to withstand higher reverse voltages, improving the device's breakdown voltage and enhancing overall stability.

[0049] The N-type GaN layer 3 and the P-type GaN layer 6 are in ohmic contact with electrode 8. Electrode 8 introduces external current into the diode, supporting normal device operation. Good electrode design is crucial for reducing contact resistance and improving device efficiency and stability.

[0050] In one possible implementation, the active layer comprises five pairs of indium-component gradient quantum wells formed by alternating stacks of InGaN and GaN.

[0051] In this embodiment of the invention, a gradient indium composition quantum well design, formed by alternating stacks of five pairs of InGaN and GaN cells in the active layer, effectively optimizes carrier injection efficiency and reduces stress problems caused by lattice mismatch. This gradient indium composition design modulates the band structure of the quantum well through gradual changes in indium composition, thereby improving light emission efficiency and quantum efficiency. Furthermore, the gradient indium composition helps improve the optical properties of the material, enabling the light-emitting diode to achieve efficient light emission across different wavelength ranges, thus improving overall light output and device performance.

[0052] In one possible implementation, the band structure of the indium-component gradient sub-well exhibits an asymmetric trapezoidal shape.

[0053] It should be noted that in semiconductor materials, the energy levels of electrons change with their spatial position. For indium-concentrated gradient quantum wells, the band structure change mainly manifests as a change in the energy bands within the quantum well, which is caused by the different indium content within the quantum well.

[0054] In this embodiment of the invention, the asymmetric trapezoidal indium-based gradient quantum well bandgap design helps optimize carrier injection and recombination processes. The trapezoidal bandgap structure effectively reduces carrier escape and increases the recombination probability within the quantum well, thereby improving light emission efficiency. Furthermore, the asymmetric bandgap allows electrons and holes to be better confined and recombine within the quantum well, further enhancing quantum efficiency and overall light output. This design helps reduce device efficiency degradation and improves the performance and stability of light-emitting diodes, particularly in high-power and high-brightness applications.

[0055] Reference manual attached Figure 2 This invention provides a band structure variation method for an indium-component gradient sub-well.

[0056] In one possible implementation, the band gradient thickness of the indium composition gradient subwell near the N-type GaN layer 3 is 0.5 nm, the band maintenance thickness in the middle of the indium composition gradient subwell is 1.1 nm, and the band gradient thickness of the indium composition gradient subwell near the P-type GaN layer 6 is 1.3 nm.

[0057] In this embodiment of the invention, different regions of the indium-component gradient quantum well have different band gradient thicknesses, which can effectively regulate the distribution and recombination process of charge carriers. A thin band gradient of 0.5 nm near the N-type GaN layer helps enhance electron injection efficiency, ensuring that electrons can more easily enter the quantum well; while a thicker band gradient of 1.1 nm in the middle region maintains a high electron-hole recombination probability, improving light emission efficiency; a thicker band gradient of 1.3 nm near the P-type GaN layer helps slow down hole loss, ensuring that holes can fully recombine within the quantum well. Overall, this design improves quantum efficiency, enhances luminescence intensity, and improves device performance and stability by optimizing the band structure in different regions.

[0058] Reference manual attached Figure 3 This invention provides a structure for an edge termination layer 7, comprising a fully compensated layer 71 and a partially compensated layer 72. The fully compensated layer 71 is doped with N ions to balance the concentrations of P-type and N-type dopants, resulting in a net charge of zero in the fully compensated layer 71. In the partially compensated layer 72, the N ion doping concentration near the P-type GaN layer 6 is greater than the N ion doping concentration away from the P-type GaN layer 6, creating a gradually varying charge distribution in the partially compensated layer 72.

[0059] In this embodiment of the invention, the design of a fully compensated layer 71 and a partially compensated layer 72 in the edge termination layer can effectively optimize the electric field distribution and improve the stability and breakdown voltage of the device. The fully compensated layer 71, by balancing the concentrations of P-type and N-type dopants, achieves a net charge of zero, smoothing the electric field, avoiding electric field concentration, reducing electric field spikes, and thus improving the device's high-voltage withstand capability. The partially compensated layer 72, by introducing a higher N-ion doping concentration near the P-type GaN layer and a lower doping concentration away from the P-type GaN layer, forms a gradually changing charge distribution. This gradient doping design effectively alleviates electric field congestion, further optimizes the electric field distribution of the device, improves the device's breakdown voltage, and enhances its stability during high-voltage operation.

[0060] In one possible implementation, the N-ion doping concentration at each location in the partial compensation layer 72 is specifically as follows:

[0061]

[0062] in, N x This indicates the N-ion doping concentration at the current location. N 0 indicates the initial doping concentration. e Let α represent the natural constant and α represent the decay factor. x This indicates the distance between the current location and the P-type GaN layer.

[0063] In this embodiment of the invention, by introducing exponential decay, the doping concentration is higher near the P-type GaN layer and gradually decreases further away. This design enables a gradual change in charge distribution, effectively smoothing the electric field distribution, avoiding electric field concentration at the edges, reducing electric field spikes, and improving the breakdown voltage of the device. The exponential decay doping concentration design ensures that the partial compensation layer 72 optimizes the electric field while improving the stability of the device at high voltages, reducing breakdown caused by electric field congestion, and thus improving the LED's withstand voltage and long-term operating stability.

[0064] Reference manual attached Figure 4 This invention provides one possible implementation of a partial compensation layer 72, which includes a first region 721, a second region 722, and a third region 723. The first region 721 is located near the p-type GaN layer 6, the second region 722 is located in the middle, and the third region 723 is located away from the p-type GaN layer 6. The N-ion doping concentration in the first region 721 is greater than that in the second region 722, and the N-ion doping concentration in the second region 722 is greater than that in the third region 723.

[0065] In this embodiment of the invention, the partial compensation layer 72 forms a gradually decreasing doping concentration gradient by dividing the N-ion doping concentration into a first region 721, a second region 722, and a third region 723. The doping concentration is higher on the side closer to the P-type GaN layer, gradually decreasing to the region farther away from the P-type GaN layer. This design helps to smooth the electric field distribution, reduce electric field spikes and electric field congestion, thereby optimizing the electric field structure of the device. By using different doping concentrations in different regions, the breakdown voltage and stability of the device can be effectively improved, breakdown caused by electric field concentration can be avoided, and the reliability of the LED under high voltage operation can be enhanced. In addition, the gradient doping design can also improve the tolerance of the manufacturing process and reduce the impact of doping inhomogeneity on device performance.

[0066] Reference manual attached Figure 5The diagram shows a flow chart of a preparation method provided by an embodiment of the present invention.

[0067] This invention provides a fabrication method for preparing the above-mentioned gallium nitride-based light-emitting diode epitaxial structure. The fabrication method includes:

[0068] S1: Construct a simulation model of the epitaxial structure of a gallium nitride-based light-emitting diode.

[0069] Specifically, the simulation model of the epitaxial structure of gallium nitride-based light-emitting diodes is described by the Poisson equation, the continuity equation of electrons and holes, and the drift-diffusion current equation of electrons and holes.

[0070] The Poisson equation is used to calculate the potential distribution within a semiconductor device, and its expression is:

[0071]

[0072] in, ε This represents the dielectric constant of a semiconductor. This represents gradient operation. Represents electric potential, q Represents the fundamental charge of an electron. p Represents hole density. n Represents electron density, N D Indicates the donor concentration of ionized donors. N A This indicates the concentration of ionized acceptors.

[0073] The continuity equations for electrons and holes describe the conservation of charge, as follows:

[0074]

[0075] in, J n This represents the current density of electrons. J p This represents the current density of holes. R n Indicates the recombination rate of electrons. R p This represents the recombination rate of holes. G n Indicates the rate of electron generation. G p This represents the hole generation rate. This represents the partial derivative operation. t Indicates time.

[0076] The drift-diffusion current equations for electrons and holes are as follows:

[0077]

[0078] in, μ n Indicates electron mobility. μ p This represents the hole mobility. D n The diffusion coefficient of electrons is represented by... D p This represents the diffusion coefficient of holes.

[0079] S2: Determine the reverse breakdown voltage of the gallium nitride-based light-emitting diode epitaxial structure under various structural parameters through simulation models.

[0080] The reverse breakdown voltage refers to the maximum voltage that a semiconductor device, such as a diode or light-emitting diode, can withstand under reverse bias conditions. When the reverse bias voltage exceeds this voltage, the device current increases sharply, causing it to enter a breakdown state and lose its normal operating capability. As the reverse voltage increases, the electric field in the depletion region gradually increases until it reaches a critical value, causing a strong avalanche effect or breakdown effect of charge carriers, resulting in a sharp increase in current. At this point, the reverse breakdown voltage of the device is reached, and the equipment may be damaged or fail.

[0081] S3: Determine the optimal structural parameters of the gallium nitride-based light-emitting diode epitaxial structure based on the reverse breakdown voltage under various structural parameters.

[0082] Optionally, the structural parameters include: the thickness of the N-type GaN layer 3, the thickness of the active layer 4, the band change shape of the indium composition gradient sub-well, the thickness of the P-type GaN layer 6, the thickness of the edge termination layer 7, and the N-ion doping concentration in each region of the edge termination layer 7.

[0083] In one possible implementation, S3 specifically involves determining the optimal structural parameters of the gallium nitride-based light-emitting diode epitaxial structure using the Seagull optimization algorithm based on the reverse breakdown voltage under various structural parameters.

[0084] Specifically, the reverse breakdown voltage can be used as the fitness function of the Seagull optimization algorithm.

[0085] Initialize seagull individuals. Each seagull individual represents a feasible set of structural parameters. Each seagull individual consists of multiple dimensional components, and each component represents a structural parameter.

[0086] During the global search phase, collisions are avoided and the movement proceeds towards the optimal individual:

[0087]

[0088] in, Indicates the first t During the nth iteration i The location of an individual seagull after the global search phase. Indicates the first t During the nth iteration i The positions of individual seagulls after collision protection treatment A Indicates control factor. Indicates the first t During the nth iteration i The location of each individual seagull Indicates the first t During the nth iteration i The displacement of each seagull towards the optimal individual. B Indicates the search balance factor. Indicates the first t The optimal individual position in the next iteration.

[0089] In this embodiment of the invention, during the global search phase, the position update strategy of individual seagulls can be effectively optimized by avoiding collisions and moving towards the optimal individual. Guided by control factors and search balance factors, the seagulls avoid the trap of local optima during the search process, while ensuring the balance and diversity of the search. By combining the displacement of the current position with the movement towards the optimal individual position, this method allows the seagulls to gradually approach the optimal solution within a broad search space, effectively reducing collisions between different individuals, avoiding ineffective resource consumption, and ultimately achieving more efficient and accurate parameter optimization. This method helps improve overall search efficiency, accelerates the convergence process, and ensures that the optimal design solution is found.

[0090]

[0091] in, t Indicates the current iteration number. T Indicates the maximum number of iterations. f c This indicates the linearly decreasing frequency.

[0092] In this embodiment of the invention, the control factor gradually decreases with the increase of the number of iterations. This helps maintain a large search range in the early stages of the optimization process, encouraging individual seagulls to explore the solution space more extensively, thereby avoiding premature entrapment in local optima. As iterations proceed, the control factor gradually decreases, making the search process more refined, focusing on the vicinity of the optimal solution, improving convergence and accelerating the arrival at the optimal solution. This method balances exploration and development during the optimization process, effectively broadening the search while ensuring precise searching for the optimal solution.

[0093]

[0094] in, r 1 Represents a random number between 0 and 1.

[0095] In this embodiment of the invention, the speed and range at which an individual approaches the optimal solution during the search process can be dynamically adjusted. The introduction of random numbers introduces uncertainty, enabling the algorithm to maintain a balance between global and local searches, thus avoiding premature convergence. The balance factor decreases as the control factor decreases, thereby gradually reducing randomness in the search process, enhancing fine-grained search capabilities, and helping to accurately find the optimal solution. This method can maintain search breadth while avoiding excessive fluctuations during the search process, improving the stability and convergence efficiency of the algorithm.

[0096] During the local search phase, a random number is generated. r 2 According to random numbers r 2 The search strategy and the encirclement strategy are selected in parallel, and the displacement is performed in a spiral motion:

[0097]

[0098] in, Indicates the first t During the nth iteration i The position of an individual seagull after spiraling. x express x Directional spiral flight coefficient, y express y Directional spiral flight coefficient, z express z Directional spiral flight coefficient, r Indicates the radius of the spiral flight trajectory. θ Represents a random number between 0 and 2π. u , v Represents the helical constant. e Represents the natural constant.

[0099] In this embodiment of the invention, by introducing a combination of spiral search and encirclement strategies during the local search phase, and generating random numbers to determine which strategy to adopt, the diversity and flexibility of the search process can be effectively enhanced. The spiral movement allows individual seagulls to effectively explore in different directions during the search, forming a purposeful spiral trajectory in the search space, thus avoiding the predicament of local optima. By randomly selecting either a spiral search or encirclement strategy, the algorithm can adaptively adjust its search method according to the current search state. This enhances the ability to perform local searches, especially when approaching the optimal solution, enabling more refined optimization and improving the algorithm's convergence speed and accuracy.

[0100] Perform mutation operations on each individual seagull:

[0101]

[0102] in, Indicates the first t During the nth iteration i The location of the individual seagull after mutation. P r Represents a random individual. ω This represents the adaptive scaling factor.

[0103] In this embodiment of the invention, performing mutation operations introduces a degree of randomness and diversity into the search process, preventing the algorithm from getting trapped in local optima. This increases the ability of individuals to jump within the solution space, improves the flexibility of the search process, and enhances the algorithm's global search capability and convergence speed.

[0104]

[0105] in, ω max Indicates the maximum scaling factor. ω min This represents the minimum scaling factor.

[0106] In this embodiment of the invention, in the early stages of the optimization process, a larger scaling factor can promote a broader search, helping individual seagulls explore the solution space and avoid getting trapped in local optima. As the number of iterations increases, the scaling factor gradually decreases, reducing the mutation amplitude and making the search more refined, focusing on the neighborhood of the optimal solution. This dynamic adjustment helps maintain a balance between global and local search, improving the algorithm's search efficiency and convergence speed, while also enhancing the algorithm's stability and adaptability.

[0107] Determine if the fitness value of the mutated position is greater than the fitness value of the original position. If so, replace the original position with the mutated position. Otherwise, leave the original position unchanged.

[0108] Update the fitness values ​​of each individual seagull and the globally optimal individual.

[0109] Determine if the current iteration count has reached the maximum iteration count. If yes, output the set of structure parameters represented by the seagull with the highest fitness. Otherwise, return to continue iterating.

[0110] In this embodiment of the invention, by using the Seagull optimization algorithm, the optimal parameter combination can be efficiently found in a multi-dimensional design space to optimize LED performance, particularly in improving reverse breakdown voltage, light extraction efficiency, and device stability. Compared with traditional empirical design methods, the Seagull optimization algorithm avoids getting trapped in local optima through global and local search strategies, and can take into account complex design constraints and performance requirements, providing a more accurate and reliable optimization scheme, thereby improving the overall performance and long-term reliability of the device.

[0111] S4: According to the optimal structural parameters, an AlN nucleation layer 2 is deposited on the sapphire substrate 1 by radio frequency sputtering.

[0112] S5: By selectively depositing argon ions into a portion of the region, multiple pores are generated on the AlN nucleation layer 2, and the pores form a light scattering structure.

[0113] S6: An N-type GaN layer 3 is deposited on the AlN nucleation layer 2 by chemical vapor deposition.

[0114] S7: InGaN and GaN are alternately stacked and deposited on the N-type GaN layer 3 by chemical vapor deposition to form an active layer 4 with an indium composition gradient quantum well.

[0115] S8: An electron blocking layer 5 is deposited on the active layer 4 by chemical vapor deposition.

[0116] S9: A P-type GaN layer 6 is deposited on the electron blocking layer 5 by chemical vapor deposition.

[0117] S10: N ions are doped at the edge of the P-type GaN layer 6. The N ion doping concentration on the side closer to the P-type GaN layer 6 is greater than that on the side farther away from the P-type GaN layer 6, forming an edge termination layer 7 with a gradually changing charge distribution.

[0118] S11: Connect electrode 8 on N-type GaN layer 3 and P-type GaN layer 6.

[0119] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gallium nitride-based light-emitting diode epitaxial structure, characterized in that, include: Substrate; An AlN nucleation layer is disposed on the substrate, and the AlN nucleation layer has a plurality of pores for forming a light scattering structure; An N-type GaN layer is disposed on the AlN nucleation layer; An active layer is disposed on the N-type GaN layer, and the active layer includes multiple pairs of indium composition gradient sub-wells formed by alternating stacking of InGaN and GaN; An electron blocking layer is disposed on the active layer; A p-type GaN layer is disposed on the electron blocking layer; An edge termination layer is disposed at the lateral edge of the P-type GaN layer. The edge termination layer has a concentration gradient of N-ion doping, which is such that the N-ion doping concentration on the side closer to the P-type GaN layer is greater than the N-ion doping concentration on the side farther away from the P-type GaN layer. The electrodes form ohmic contacts with the N-type GaN layer and the P-type GaN layer, respectively. The edge termination layer includes a full compensation layer and a partial compensation layer; the full compensation layer is doped with N ions to balance the concentrations of P-type and N-type dopants, so that the net charge in the full compensation layer is zero; the N ion doping concentration in the partial compensation layer is greater on the side closer to the P-type GaN layer than on the side farther from the P-type GaN layer, forming a gradually changing charge distribution in the partial compensation layer. The specific N-ion doping concentration at each location in the partial compensation layer is as follows: Where, N x The current position represents the N-ion doping concentration, N0 represents the initial doping concentration, e represents the natural constant, α represents the decay factor, and x represents the distance between the current position and the P-type GaN layer. The partial compensation layer includes a first region, a second region, and a third region arranged sequentially along a direction away from the P-type GaN layer, and the N-ion doping concentration of the first region, the second region, and the third region decreases sequentially.

2. The gallium nitride-based light-emitting diode epitaxial structure according to claim 1, characterized in that, The band structure of the indium-component gradient sub-well is an asymmetric trapezoidal shape.

3. The gallium nitride-based light-emitting diode epitaxial structure according to claim 2, characterized in that, The band gradient thickness of the indium-component gradient quantum well near the N-type GaN layer is 0.5 nm, the band maintenance thickness in the middle is 1.1 nm, and the band gradient thickness near the P-type GaN layer is 1.3 nm.

4. A method for fabricating a gallium nitride-based light-emitting diode epitaxial structure, characterized in that, The method for fabricating the gallium nitride-based light-emitting diode epitaxial structure according to any one of claims 1 to 3 includes: S1: Construct a simulation model of the epitaxial structure of a gallium nitride-based light-emitting diode, and describe the simulation model using the Poisson equation, the continuity equation of electrons and holes, and the drift-diffusion current equation of electrons and holes; The Poisson equation is used to calculate the potential distribution within a semiconductor device, and its expression is: Where ε represents the dielectric constant of the semiconductor, This represents gradient operation. Let N represent electric potential, q represent the elementary charge of an electron, p represent the hole density, n represent the electron density, and N represent the electron density. D N represents the donor concentration of ionization. A Indicates the concentration of ionized acceptors; The continuity equations for electrons and holes describe the conservation of charge, as follows: in, This represents the current density of electrons. R represents the current density of holes. n R represents the recombination rate of electrons. p G represents the recombination rate of holes. n G represents the rate of electron formation. p This represents the hole generation rate. This represents the partial derivative operation, and t represents time. The drift-diffusion current equations for electrons and holes are as follows: Where, μ n μ represents the mobility of electrons. p D represents the hole mobility. n D represents the diffusion coefficient of electrons. p This represents the diffusion coefficient of holes; S2: Using the simulation model, determine the reverse breakdown voltage of the gallium nitride-based light-emitting diode epitaxial structure under various structural parameters; S3: Based on the reverse breakdown voltage under various structural parameters, the optimal structural parameters of the gallium nitride-based light-emitting diode epitaxial structure are determined using the Seagull optimization algorithm. Specifically, this includes: using the reverse breakdown voltage as the fitness function of the Seagull optimization algorithm; initializing Seagull individuals, each representing a feasible set of structural parameters; avoiding collisions and moving towards the optimal individual during the global search phase; generating a random number during the local search phase, and selecting between a spiral search strategy and an encirclement strategy in parallel based on the random number, moving in a spiral motion; performing mutation operations on each Seagull individual to prevent the algorithm from getting trapped in local optima; determining whether the fitness value of the mutated position is greater than the fitness value of the position before mutation; if so, replacing the position before mutation with the mutated position; updating the fitness values ​​of each Seagull individual and the global optimal individual; determining whether the current iteration count has reached the maximum iteration count; if so, outputting the set of structural parameters represented by the Seagull individual with the highest current fitness. S4: According to the optimal structural parameters, an AlN nucleation layer is deposited on the substrate by radio frequency sputtering; S5: By selectively depositing argon ions into a portion of the AlN nucleation layer, multiple pores are generated to form a light-scattering structure. S6: An N-type GaN layer is deposited on the AlN nucleation layer by chemical vapor deposition; S7: By chemical vapor deposition, InGaN and GaN are alternately stacked and deposited on the N-type GaN layer to form an active layer with an indium composition gradient quantum well; S8: An electron blocking layer is deposited on the active layer by chemical vapor deposition; S9: A P-type GaN layer is deposited on the electron blocking layer by chemical vapor deposition; S10: N ions are doped into the edge of the P-type GaN layer, and the N ion doping concentration on the side closer to the P-type GaN layer is greater than the N ion doping concentration on the side farther away from the P-type GaN layer, forming an edge termination layer with a gradually changing charge distribution. S11: Connect electrodes on the N-type GaN layer and the P-type GaN layer.

5. The preparation method according to claim 4, characterized in that, The structural parameters include: the thickness of the N-type GaN layer, the thickness of the active layer, the band change shape of the indium composition gradient sub-well, the thickness of the P-type GaN layer, the thickness of the edge-stopping layer, and the N-ion doping concentration in each region of the edge-stopping layer.

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