GAN-based micro led epitaxial wafer containing multi-aluminum-nitrogen composite electron balance layer and preparation method

Abstract

The application belongs to the technical field of LED semiconductors, and more particularly relates to a GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer and a preparation method thereof.The application comprises, from bottom to top, a substrate, a low-temperature buffer layer, an undoped GaN layer, an N-type GaN layer, a composite electron balance layer, a multi-quantum well light-emitting layer, and a P-type GaN layer; the composite electron balance layer is composed of any two material layers selected from ScAlN, YAlN, and InAlN and an AlGaN layer, which are alternately stacked.The application adds the ScAlN / YAlN / InAlN-AlGaN alternately stacked composite electron balance layer between the N-type GaN layer and the multi-quantum well light-emitting layer, so as to achieve the effects of improving the light-emitting power of the Micro LED, reducing non-radiative recombination, enhancing the static resistance of the device, and improving the stability of large-current operation.

Description

Technical Field

[0001] This invention belongs to the field of LED semiconductor technology, and more specifically, relates to a GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer and its preparation method. Background Technology

[0002] Micro LED is a next-generation semiconductor optoelectronic display technology. With its advantages of high resolution, fast response, low power consumption, and high stability, it is widely used in miniature high-definition displays, AR / VR terminals, and automotive displays. GaN-based materials, with their wide bandgap, high electron mobility, and good luminous stability, are the mainstream materials for fabricating epitaxial wafers for blue and green Micro LEDs. Existing conventional GaN-based Micro LEDs employ a multi-layer epitaxial stacked structure, relying on N-type and P-type layers to achieve carrier injection and emitting light through multi-quantum-well radiative recombination. However, in small-size, highly integrated applications, problems such as electron-hole injection imbalance, severe carrier leakage, numerous epitaxial dislocation defects, and weak optoelectronic stability are common, leading to low device luminous efficiency and limited lifespan.

[0003] Patent document CN121933144A discloses a method for preparing a light-emitting device based on the thermionic emission effect of a quantum well using MOCVD. This method improves the carrier transport characteristics of the quantum well by optimizing the epitaxial process, and slightly improves the stability of photoelectric response. However, it does not limit and control the excess electrons on the N-type side, resulting in excessively fast electron migration rate and poor carrier matching. It still suffers from defects such as quantum well recombination imbalance and significant light emission decay.

[0004] Patent document CN120640851A discloses a red light micro light-emitting diode epitaxial wafer and its preparation method. This scheme improves lattice matching and reduces some crystal defects by optimizing the epitaxial stacking structure and growth parameters. However, the functional layer structure is simple and no dedicated electronic balance structure is set, which makes it impossible to achieve precise matching of electrons and holes. Under high current, electron leakage is significant, and the device has insufficient light emission uniformity and anti-static performance, making it difficult to adapt to high-end and high-precision display scenarios.

[0005] In addition, existing conventional buffer layers are mostly monolayer structures with limited lattice mismatch and thermal stress mitigation capabilities. Epitaxial growth is prone to dislocations and interface impurities, exacerbating nonradiative recombination losses. Traditional electronic control structures are mostly monolayer thin films with limited bandgap control capabilities, only achieving simple electron blocking and unable to finely control carrier transport, making it difficult to fundamentally solve the problem of carrier injection imbalance. At the same time, existing processes lack precise control over key parameters such as buffer layer deposition temperature, sputtering power, and cavity pressure, resulting in poor interlayer growth matching and difficulty in guaranteeing epitaxial wafer crystal quality and device yield.

[0006] Existing improvement schemes can only optimize some issues of lattice defects or carrier transport, and cannot simultaneously address stress regulation, defect suppression, carrier balance, and antistatic performance improvement. They have strong technical limitations and cannot meet the current mass production application requirements of high brightness, high uniformity, and high stability Micro LEDs.

[0007] In summary, there is an urgent need to provide a GaN-based Micro LED epitaxial wafer with a multi-element aluminum-nitrogen composite electron balance layer and its preparation method to solve the problems of electron-hole injection imbalance, severe electron leakage, numerous epitaxial defects, poor photoelectric stability, and insufficient process adaptability in the existing technology. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to add a composite electron balance layer of alternating stacked ScAlN / YAlN / InAlN-AlGaN between the N-type GaN layer and the multi-quantum-well light-emitting layer, so as to solve the problems of electron-hole injection mismatch, high dislocation density of epitaxial layer, serious device leakage, weak antistatic ability and fast light emission decay at high current in the above-mentioned background technology, thereby achieving the effects of improving the light emission power of Micro LED, reducing non-radiative recombination, enhancing the electrostatic tolerance of device and improving the stability of high current operation.

[0009] The technical terms related to this invention are explained as follows: Composite electronic balance layer: refers to a high-resistivity carrier-controlled thin film grown periodically with two of the three types of aluminum nitrides, ScAlN, YAlN, and InAlN, in combination with an AlGaN layer, and set between the N layer and the quantum well, which has multiple functions such as lattice matching, impurity adsorption, and electron current limiting.

[0010] Multi-quantum-well light-emitting layer: The core light-emitting active region of Micro LED is composed of InGaN quantum wells and GaN quantum barriers stacked alternately, where electrons and holes undergo radiative recombination to release photons.

[0011] MOCVD: Metal-Organic Chemical Vapor Deposition, the mainstream epitaxial wafer growth process, which deposits semiconductor thin films layer by layer through high-temperature reactions of metal-organic sources and nitrogen sources.

[0012] Dislocation density: an indicator of the number of lattice defects in epitaxial crystals. Defects can trap charge carriers and cause nonradiative recombination, reducing luminescence efficiency.

[0013] With carrier injection in equilibrium, the number of electrons and holes entering the quantum well tends to be equal, maximizing photon recombination efficiency.

[0014] The technical problem to be solved by this invention is achieved by the following technical solution: A GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer comprises, from bottom to top, a substrate, a low-temperature buffer layer, an undoped GaN layer, an N-type GaN layer, a composite electron balance layer, a multi-quantum-well light-emitting layer, and a P-type GaN layer, wherein: A composite electronic balance layer is disposed between the N-type GaN layer and the multi-quantum-well light-emitting layer; The composite electronic equilibrium layer is a periodic composite layer structure composed of any two functional layers selected from ScAlN, YAlN, and InAlN layers, alternately stacked with an AlGaN barrier layer. The total thickness of the composite electronic balance layer is 30nm~150nm; The thicknesses of the single-layer ScAlN layer, single-layer YAlN layer, and single-layer InAlN layer are all 5nm~30nm; The thickness of a single AlGaN layer is 10nm~40nm.

[0015] This technical solution addresses the core contradiction of excessive electrons and insufficient holes in traditional structures by embedding a composite electron balance layer between N-type GaN and the active region, thereby controlling the total amount of electron injection at the source. The lattice constants of the three aluminum nitrides, ScAlN, YAlN, and InAlN, are highly matched to the GaN substrate. During alternating growth, they can adsorb unintentional doping impurities at the epitaxial interface, preventing impurities from diffusing into the quantum well region, significantly reducing dislocation density and surface pit defects in the epitaxial film, and minimizing non-radiative recombination losses caused by defects. The alternating stacking of multi-element aluminum nitride materials and AlGaN forms a periodic high-impedance band structure, which can uniformly diffuse lateral electron current while simultaneously forming a barrier to intercept high-speed electron migration, limiting the influx of excessive electrons into the quantum well, matching the electron supply with the hole injection, and increasing the probability of carrier radiative recombination. The composite electron balance layer as a whole possesses capacitive current-limiting characteristics, suppressing electron overflow under high-current driving conditions and mitigating device light decay. Trace amounts of boron atoms fill the lattice dislocations within the thin film, stabilizing the cell structure, further reducing leakage probability, and simultaneously improving the chip's electrostatic discharge resistance. The overall structure, including the thickness and composition range of each film, has been optimized through multiple sets of comparative experiments, taking into account lattice stress release, electronic control effect and epitaxial growth efficiency, and is suitable for mass production of Micro LED chips with a size of 50μm and below.

[0016] In addition, the GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electronic balance layer proposed above according to the present invention may also have the following additional technical features: According to a preferred embodiment of the present invention, the substrate is selected from any one of sapphire substrate, Si substrate, and SiC substrate.

[0017] This technical solution utilizes three types of industry-standard substrate materials to meet the production needs of different application scenarios. Sapphire substrates are inexpensive and have excellent light transmittance, making them suitable for conventional Micro LED displays; Si substrates have outstanding thermal conductivity, making them suitable for high-power, high-current chips; and SiC substrates have the highest lattice matching degree and the lowest epitaxial layer defect density, making them suitable for high-end AR microdisplay chips.

[0018] According to a preferred embodiment of the present invention, the low-temperature buffer layer is a double-layer composite buffer structure, comprising a bottom AlN film and an upper low-temperature AlGaN buffer layer. The thickness of the underlying AlN film is 10nm~30nm; The underlying AlN film was prepared by PVD deposition at a temperature of 560℃~690℃, a sputtering power of 3100W~4500W, and a reaction pressure of 1 torr~10 torr. The upper low-temperature AlGaN buffer layer was prepared by MOCVD process.

[0019] This technical solution utilizes a dual-layer composite buffer structure. First, an ultrathin AlN film is deposited via PVD to passivate the substrate surface and prevent substrate impurities from diffusing upwards. Subsequently, an AlGaN layer is grown at low temperature via MOCVD to buffer lattice mismatch, alleviate thermal stress between the substrate and the GaN epitaxial layer, prevent film cracking and warping, and provide a flat, low-defect growth substrate for the upper undoped GaN layer.

[0020] According to a preferred embodiment of the present invention, the thickness of the undoped GaN layer is 1 μm to 3 μm, and it is grown on the upper surface of the low-temperature buffer layer.

[0021] This technical solution eliminates the interface barrier between the buffer layer and the N-type GaN layer by setting a micron-level undoped GaN transition layer, uniformizes the overall lattice quality of the epitaxial layer, prevents N-type doped Si elements from diffusing downwards and contaminating the buffer layer, ensures the integrity of the underlying crystal, and reduces the reverse leakage current of the chip.

[0022] According to a preferred embodiment of the present invention, the doping element of the N-type GaN layer is Si; The Si doping concentration is 1×10⁻⁶. 17 atoms / cm 3 ~1×10 20 atoms / cm 3 ; The thickness of the N-type GaN layer is 1 μm to 3 μm.

[0023] This technical solution balances electron supply capability and crystal quality by limiting the Si doping concentration range. Doping concentration below the lower limit leads to insufficient electron supply and low chip brightness; doping concentration above the upper limit introduces a large number of impurity defects, exacerbating nonradiative recombination. Micron-level thickness ensures uniform lateral current diffusion, avoiding current congestion in the tiny size of Micro LEDs.

[0024] According to a preferred embodiment of the present invention, the composite electron balance layer adopts a four-segment alternating stacking structure, and the specific stacking type is any one of the following: ScAlN / AlGaN / YAlN / AlGaN ScAlN / AlGaN / InAlN / AlGaN YAlN / AlGaN / InAlN / AlGaN.

[0025] This technical solution constructs a multi-level electron barrier through a four-segment alternating structure of two sets of aluminum nitride functional layers combined with an AlGaN barrier layer, which intercepts high-speed electrons in layers. Compared with a single-layer electron blocking layer, the electron control effect is significantly improved. The three stacking combinations can be flexibly switched according to the target emission wavelength and chip size. The blue Micro LED uses the ScAlN-InAlN combination, and the high-brightness display chip uses the ScAlN-YAlN combination.

[0026] According to a preferred embodiment of the present invention, the multi-quantum-well light-emitting layer is an In-type material grown in a periodically alternating manner. x Ga 1-x N-quantum well layer and GaN quantum barrier layer; The number of stacked periods of the multi-quantum-well light-emitting layers is 5 to 15; The total thickness of the multi-quantum-well light-emitting layer is 120nm~250nm.

[0027] This technical solution balances luminous efficiency and stress level by limiting the number of quantum well periods and the total thickness. Too few periods result in insufficient active area for light emission and low brightness; too many periods accumulate lattice stress, generating numerous dislocation defects and shortening device lifespan. The total thickness range is adapted to Micro LED thin epitaxial processes.

[0028] According to a preferred embodiment of the present invention, the In x Ga 1-x In the N quantum well layer, the In component x takes values ​​of 0.2 to 0.3; In x Ga 1-x The thickness of a single N-quantum well layer is 2nm~3nm; The thickness of a single GaN quantum barrier layer is 8nm~12nm.

[0029] This technical solution achieves blue light emission by precisely controlling the In composition and the thickness of the well barrier, thereby regulating the band gap; the ultrathin quantum well layer enhances the quantum confinement effect, binding electrons and holes to recombine within the well; and the relatively thick GaN barrier layer isolates carrier crosstalk between adjacent quantum wells, improving radiative recombination efficiency.

[0030] According to a preferred embodiment of the present invention, the doping element of the P-type GaN layer is Mg; Mg doping concentration is 2×10 18 atoms / cm 3 ~7×10 20 atoms / cm 3 ; The thickness of the p-type GaN layer is 30nm~180nm.

[0031] This technical solution increases the hole supply by high-concentration Mg doping, matching the total number of electrons after the electron balance layer is regulated; the lower limit of the thickness ensures ohmic contact performance, while the upper limit avoids the light absorption loss caused by the thick P layer, thus balancing the luminous brightness and electrode conductivity.

[0032] In another aspect, the present invention also provides a method for preparing a GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electronic balance layer.

[0033] A method for fabricating a GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electronic equilibrium layer includes the following steps: S1. Provide a substrate and perform surface pretreatment on the substrate; S2. An AlN thin film with a thickness of 10nm~30nm is deposited on the substrate surface using PVD process, with a deposition temperature of 560℃~690℃, a sputtering power of 3100W~4500W, and a reaction pressure of 1torr~10torr; then a low-temperature AlGaN buffer layer is grown using MOCVD process to complete the preparation of the low-temperature buffer layer. S3. Grow an undoped GaN layer with a thickness of 1μm~3μm above the low-temperature buffer layer; S4. Grow a Si-doped N-type GaN layer on top of the undoped GaN layer, with a Si doping concentration of 1×10¹. 7 atoms / cm³ ~ 1×10² 0 atoms / cm³, with a thickness of 1μm~3μm; S5. Alternately grow any two types of multi-element aluminum nitride functional layers and AlGaN barrier layers on the surface of the N-type GaN layer to prepare a composite electronic balance layer with a total thickness of 30nm~150nm. S6. In with 5-15 cycles and a total thickness of 120nm-250nm is grown above the composite electron equilibrium layer. x Ga1-x N / GaN multi-quantum-well light-emitting layer; S7. A Mg-doped P-type GaN layer is grown on the surface of the multi-quantum-well light-emitting layer, with a Mg doping concentration of 2 × 10⁻⁶. 18 atoms / cm 3 ~7×10 20 atoms / cm 3 The thickness ranges from 30nm to 180nm; S8. Anneal the entire epitaxial wafer under a nitrogen atmosphere at a temperature of 600℃~850℃ for 1min~10min. After cooling to room temperature, the preparation is complete.

[0034] This technical solution employs a composite MOCVD and PVD process to complete the deposition of each epitaxial thin film stepwise. The process parameters are within a mild range, and the equipment is highly compatible, requiring no modification to existing production equipment. The process involves segmented growth of a low-temperature buffer layer, medium-temperature deposition of a composite electron equilibrium layer, low-temperature growth of a quantum well, and high-temperature activation and doping of the P-type layer. Stepwise temperature control avoids problems such as high-temperature decomposition and lattice mismatch. The annealing step activates Mg doping in the P-type layer, increasing the hole concentration. The entire process can be continuously mass-produced, achieving production efficiency comparable to traditional epitaxial processes.

[0035] The one or more technical solutions provided by this invention have the following advantages compared with the prior art: (1) The present invention sets a composite electron balance layer between the N layer and the quantum well, intercepts excess electrons in advance, realizes electron-hole injection balance, significantly improves the radiative recombination efficiency in the quantum well, and increases the chip luminous power by more than 15% under the same current.

[0036] (2) The alternating structure of ScAlN / YAlN / InAlN adsorbs interface impurities and matches the lattice, reduces the dislocation density of the epitaxial layer, reduces non-radiative recombination of defects, and improves the chip's anti-static breakdown capability, thereby increasing the device yield by 8%~12%.

[0037] (3) The composite electronic balance layer has the characteristics of current limiting capacitor, which suppresses electron leakage under high current drive, alleviates light decay, extends the service life of Micro LED display screen, and is suitable for high brightness and high refresh rate display scenarios. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the GAN-based Micro LED epitaxial wafer of this invention.

[0039] Figure 2 This is a flowchart illustrating the preparation method of the present invention.

[0040] In the figure: 100, substrate; 200, low temperature buffer layer; 300, undoped GaN layer; 400, N-type GaN layer; 500, composite electron balance layer; 600, multi-quantum well light-emitting layer; 700, P-type GaN layer. Detailed Implementation

[0041] Example 1 This embodiment provides a GaN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electronic balance layer, such as... Figure 1 As shown, the epitaxial structure, from bottom to top, includes a substrate 100, a low-temperature buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, a composite electron balance layer 500, a multi-quantum-well light-emitting layer 600, and a P-type GaN layer 700.

[0042] Substrate 100 is selected from sapphire substrate; The low-temperature buffer layer 200 is a two-layer composite structure, including a bottom AlN film and an upper low-temperature AlGaN buffer layer. The bottom AlN film has a thickness of 25nm. The undoped GaN layer 300 is 1.8 μm thick and is grown on the upper surface of the low-temperature buffer layer 200; The N-type GaN layer 400 is a Si-doped GaN layer with a Si doping concentration of 3 × 10⁻⁶. 19 atoms / cm 3 Thickness 2.5μm; The composite electronic balance layer 500 has a four-segment alternating stacking structure, with the stacking order being ScAlN / AlGaN / InAlN / AlGaN. The thickness of a single ScAlN layer is 15nm, corresponding to an AlGaN thickness of 20nm. The thickness of a single InAlN layer is 20nm, corresponding to an AlGaN thickness of 30nm. The total thickness of the electronic balance layer is 85nm. The multi-quantum-well light-emitting layer 600 is an In-type layer that is periodically and alternately grown. x Ga 1-x The N quantum well layer and GaN quantum barrier layer have 11 cycles, an In composition of x=0.25, a single-layer quantum well thickness of 2.5nm, and a single-layer quantum barrier thickness of 10nm. The p-type GaN layer 700 is a Mg-doped GaN layer with a Mg doping concentration of 3 × 10⁻⁶. 20 atoms / cm 3 Thickness 150nm.

[0043] The preparation method of this embodiment, such as Figure 2 As shown, the process includes the following steps: S1. Provide a sapphire substrate and perform a high-temperature hydrogen purging pretreatment on the substrate; S2. A bottom AlN thin film is deposited on the surface of substrate 100 using PVD process at a deposition temperature of 560℃~690℃, a sputtering power of 3100W~4500W, a reaction pressure of 1 torr~10 torr, and a deposition thickness of 25nm. Then, it is transferred to an MOCVD equipment for hydrogen cleaning at a temperature of 1000℃~1150℃ and a pressure of 20 torr~250 torr. The temperature is then lowered to 500℃~680℃ and a pressure of 100 torr~650 torr to grow a low-temperature AlGaN buffer layer. Finally, it is annealed in situ at 1000℃~1200℃ and 100 torr~600 torr in a hydrogen atmosphere. S3. An undoped GaN layer 300 is grown above the low-temperature buffer layer 200 at a growth temperature of 900℃~1150℃, a pressure of 20 torr~550 torr, and a growth thickness of 1.8μm. S4. Grow an N-type GaN layer 400 above the undoped GaN layer 300 at a growth temperature of 1000℃~1200℃ and a pressure of 50 torr~500 torr. The Si doping concentration is 3×10⁻⁶. 19 atoms / cm 3 The growth thickness is 2.5 μm; S5. A composite electron equilibrium layer 500 is grown above the N-type GaN layer 400 at a growth temperature of 750℃~1000℃ and a pressure of 100 torr~500 torr. 15nm ScAlN, 20nm AlGaN, 20nm InAlN, and 30nm AlGaN are grown alternately in sequence. S6. A multi-quantum well light-emitting layer 600 is grown above the composite electronic balance layer 500. The well layer growth temperature is 745℃, the barrier layer growth temperature is 880℃, the reaction pressure is 80 torr~550 torr, and the number of cycles is 11. S7. Grow a P-type GaN layer 700 above the multi-quantum-well light-emitting layer 600 at a growth temperature of 850℃~1100℃ and a pressure of 100 torr~650 torr, with a Mg doping concentration of 3×10⁻⁶. 20 atoms / cm 3 Thickness 150nm; S8. After epitaxial growth is completed, annealing is performed under a nitrogen atmosphere at a temperature of 600℃~850℃ for 1min~10min. The temperature is then lowered to room temperature to complete the preparation of the epitaxial wafer.

[0044] Example 2 This embodiment provides a GaN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer. The overall structure, material of each layer and basic parameters are consistent with those of Embodiment 1, with only the stacking structure and single-layer thickness parameters of the composite electron balance layer 500 being adjusted.

[0045] In this embodiment, the stacking order of the composite electronic balance layer 500 is ScAlN / AlGaN / YAlN / AlGaN; The thickness of a single-layer ScAlN is 15nm, which corresponds to the thickness of AlGaN being 25nm. A single layer of YAlN has a thickness of 20nm, which corresponds to a thickness of 30nm for AlGaN. The total thickness of the electron balance layer is 90 nm.

[0046] The preparation process parameters in this embodiment are completely consistent with those in Example 1. The only difference is that the In source is switched to the Y source during the electron equilibrium layer growth stage. All other growth temperature, pressure, timing, and annealing parameters remain unchanged.

[0047] Example 3 This embodiment provides a GaN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electronic balance layer. The overall structure, material of each layer and basic parameters are consistent with those of Embodiment 1. The stacking order of the composite electronic balance layer 500 is YAlN / AlGaN / InAlN / AlGaN. A single layer of YAlN has a thickness of 15nm, which corresponds to a thickness of 25nm for AlGaN. A single layer of InAlN has a thickness of 20nm, which corresponds to a thickness of 30nm for AlGaN. The total thickness of the electron balance layer is 90 nm.

[0048] The preparation process in this embodiment is consistent with that in Embodiments 1 and 2, with only the type of metal-organic source being adjusted.

[0049] Example 4 This embodiment provides a GaN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer. The overall structure, material of each layer and basic parameters are consistent with those of Embodiment 1, with only the thickness parameter of the 500 single layer of the composite electron balance layer being adjusted.

[0050] The stacking order of the composite electronic equilibrium layer 500 is ScAlN / AlGaN / InAlN / AlGaN; A single layer of ScAlN has a thickness of 5nm, which corresponds to a thickness of 10nm for AlGaN. A single layer of InAlN has a thickness of 10nm, which corresponds to a thickness of 20nm for AlGaN. The total thickness of the electron balance layer is 45 nm.

[0051] The preparation process in this embodiment is the same as that in Example 1.

[0052] Example 5 This embodiment provides a GaN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer. The overall structure, material of each layer and basic parameters are consistent with those of Embodiment 1, with only the thickness parameter of the 500 single layer of the composite electron balance layer being adjusted.

[0053] The stacking order of the composite electronic equilibrium layer 500 is ScAlN / AlGaN / InAlN / AlGaN; The thickness of a single-layer ScAlN is 30nm, which corresponds to the thickness of AlGaN being 40nm. A single layer of InAlN has a thickness of 30nm, which corresponds to a thickness of 40nm for AlGaN. The total thickness of the electron balance layer is 140 nm.

[0054] The preparation process in this embodiment is the same as that in Example 1.

[0055] Comparative Example 1 This comparative example provides a Micro LED epitaxial wafer structure. The overall epitaxial layer stacking order, material, and growth process are the same as in Example 1. The difference is that the composite electronic balance layer 500 is removed, and a stress-relieving superlattice layer is set between the N-type GaN layer 400 and the multi-quantum well light-emitting layer 600. The stress-relieving superlattice layer is In x Ga 1-x The N / GaN alternating stacked structure has 14 cycles. Single layer In x Ga 1-x The thickness of N is 3nm, and the thickness of a single GaN layer is 3nm. In x Ga 1-x Nitrogen (N) growth temperature: 880℃; GaN growth temperature: 950℃.

[0056] Comparative Example 2 This comparative example provides a Micro LED epitaxial wafer structure. The overall structure, parameters, and process are the same as those in Example 1. The difference is that the composite electronic balance layer 500 retains only the ScAlN / AlGaN two-layer structure and removes the InAlN / AlGaN stacked structure.

[0057] Comparative Example 3 This comparative example provides a Micro LED epitaxial wafer structure. The overall structure, parameters, and process are the same as those in Example 1. The difference is that the composite electronic balance layer 500 retains only the InAlN / AlGaN two-layer structure and removes the ScAlN / AlGaN stacked structure.

[0058] The epitaxial wafers of Examples 1-5 and Comparative Examples 1-3 were uniformly fabricated into Micro LED chips with a specification of 50μm×50μm. Under the same test environment and driving current conditions, the luminous power and electrostatic discharge (ESD) withstand voltage performance of the devices were tested. The test results show that, compared to Comparative Example 1, Examples 1-3 with the complete composite structure exhibited a 16%-22% increase in luminous power and an ESD withstand voltage increase of over 30%; while Comparative Examples 2 and 3, which retained only a single-layer aluminum-nitrogen composite structure, showed performance improvements of less than 10%. Therefore, it can be concluded that the composite electron balance layer structure of this invention, which uses any two multi-element aluminum-nitrogen layers combined with alternating AlGaN stacks, is the core structural feature for improving the luminous efficiency and ESD withstand performance of Micro LEDs.

[0059] It should be noted that the present invention is not limited to the above-described embodiments. Any equivalent substitutions, parameter fine-tuning, or simple changes in stacking order made within the technical scope disclosed in the present invention are all within the protection scope of the present invention.

Claims

1. A GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer, characterized in that, The layers stacked from bottom to top include: a substrate (100), a low-temperature buffer layer (200), an undoped GaN layer (300), an N-type GaN layer (400), a composite electron balance layer (500), a multi-quantum-well light-emitting layer (600), and a P-type GaN layer (700), wherein: A composite electronic balance layer (500) is disposed between an N-type GaN layer (400) and a multi-quantum well light-emitting layer (600); The composite electronic equilibrium layer (500) is a periodic composite layer structure composed of any two functional layers selected from ScAlN, YAlN, and InAlN layers, and an AlGaN barrier layer, arranged alternately. The total thickness of the composite electronic balance layer (500) is 30nm~150nm; The thicknesses of the single-layer ScAlN layer, single-layer YAlN layer, and single-layer InAlN layer are all 5nm~30nm; The thickness of a single AlGaN layer is 10nm~40nm.

2. The GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in claim 1, characterized in that: The substrate (100) is selected from any one of sapphire substrate, Si substrate, and SiC substrate.

3. The GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in claim 1, characterized in that: The low-temperature buffer layer (200) is a double-layer composite buffer structure, comprising a bottom AlN film and an upper low-temperature AlGaN buffer layer; The thickness of the underlying AlN film is 10nm~30nm; The underlying AlN film was prepared by PVD deposition at temperatures of 560℃ and 690℃, sputtering power of 3100W and 4500W, and reaction pressure of 1 torr to 10 torr. The upper low-temperature AlGaN buffer layer was prepared by MOCVD process.

4. The GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in claim 1, characterized in that: The undoped GaN layer (300) has a thickness of 1 μm to 3 μm and is grown on the upper surface of the low-temperature buffer layer (200).

5. The GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in claim 1, characterized in that: The doping element of the N-type GaN layer (400) is Si; The Si doping concentration is 1×10⁻⁶. 17 atoms / cm³ ~1×10 20 atoms / cm 3 ; The thickness of the N-type GaN layer (400) is 1μm~3μm.

6. The GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in claim 1, characterized in that: The composite electron balance layer (500) adopts a four-segment alternating stacking structure, and the specific stacking type is any one of the following: ScAlN / AlGaN / YAlN / AlGaN ScAlN / AlGaN / InAlN / AlGaN YAlN / AlGaN / InAlN / AlGaN.

7. The GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in claim 1, characterized in that: The multi-quantum-well light-emitting layer (600) is an In-type layer that is periodically and alternately grown. x Ga 1-x N-quantum well layer and GaN quantum barrier layer; The number of stacked periods for the multi-quantum well light-emitting layer (600) is 5~15; The total thickness of the multi-quantum well light-emitting layer (600) is 120nm~250nm.

8. The GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in claim 7, characterized in that: The In x Ga 1-x In the N quantum well layer, the In component x takes values ​​of 0.2 to 0.3; In x Ga 1-x The thickness of a single N-quantum well layer is 2nm~3nm; The thickness of a single GaN quantum barrier layer is 8nm~12nm.

9. The GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in claim 1, characterized in that: The doping element of the P-type GaN layer (700) is Mg; Mg doping concentration is 2×10 18 atoms / cm 3 ~7×10 20 atoms / cm 3 ; The thickness of the P-type GaN layer (700) is 30nm~180nm.

10. A method for preparing a GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer, comprising the GAN-based Micro LED epitaxial wafer containing a multi-element aluminum-nitrogen composite electron balance layer as described in any one of claims 1 to 9, characterized in that: Includes the following steps: S1. Provide a substrate (100) and perform surface pretreatment on the substrate (100); S2. An AlN thin film with a thickness of 10 nm / 30 nm is deposited on the surface of the substrate (100) using PVD process. The deposition temperature is 560℃ / 690℃, the sputtering power is 3100W / 4500W, and the reaction pressure is 1 torr / 10 torr. Then, a low-temperature AlGaN buffer layer is grown using MOCVD process to form a low-temperature buffer layer (200). S3. An undoped GaN layer (300) with a thickness of 1 μm to 3 μm is grown above the low-temperature buffer layer (200); S4. A Si-doped N-type GaN layer (400) is grown above the undoped GaN layer (300), with a Si doping concentration of 1×10⁻⁶. 17 atoms / cm 3 1×10 20 atoms / cm 3 The thickness is 1μm / 3μm; S5. Two kinds of multi-element aluminum nitride functional layers and AlGaN barrier layers are alternately grown on the surface of the N-type GaN layer (400) to prepare a composite electronic balance layer (500) with a total thickness of 30nm~150nm. S6, In with 5 / 15 cycle numbers and a total thickness of 120nm / 250nm is grown above the composite electron equilibrium layer (500). x Ga 1-x N / GaN multi-quantum-well light-emitting layer (600); S7. A Mg-doped P-type GaN layer (700) is grown on the surface of the multi-quantum-well light-emitting layer (600), with a Mg doping concentration of 2 × 10⁻⁶. 18 atoms / cm 3 7×10 20 atoms / cm 3 The thickness is 30nm / 180nm; S8. Anneal the overall epitaxial structure under a nitrogen atmosphere at 600℃ / 850℃ for 1 min / 10 min, and then cool to room temperature to complete the preparation.

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