Anti-warpage gan red light led epitaxial structure

Abstract

The application relates to the technical field of semiconductor photoelectricity, and provides a warping-preventing GaN red light LED epitaxial structure. The warping-preventing GaN red light LED epitaxial structure comprises a substrate, a nucleation layer, a buffer layer, a stress releasing layer, an N-type GaN layer, a multi-quantum well light emitting layer, an electron blocking layer and a P-type GaN layer which are sequentially arranged on the substrate. A spherical cap-shaped protrusion is arranged on the substrate. Stress releasing grooves are arranged on at least part of the thicknesses of the N-type GaN layer, the multi-quantum well light emitting layer, the electron blocking layer and at least part of the thickness of the P-type GaN layer, and the stress releasing grooves are filled with filling parts. The warping-preventing GaN red light LED epitaxial structure can split the originally large-area continuous active layer into independent regions, each region can be elastically relaxed through the side wall, the accumulation of stress loses the continuity condition, and the warping and deformation of the red light LED epitaxial structure can be avoided.

Description

Technical Field

[0001] This application relates to the field of semiconductor optoelectronic technology, and in particular to an anti-warping GaN red LED epitaxial structure. Background Technology

[0002] Currently, GaN-based LED devices with InGaN quantum wells as the active layer are widely used in various fields. However, due to the lack of suitable homogeneous epitaxial substrates, GaN is usually grown on sapphire, silicon carbide, or silicon substrates with significant lattice mismatch. Therefore, traditional GaN-based red LEDs suffer from internal stress during the manufacturing process due to dislocation defects formed between GaN and the substrate, causing the entire epitaxial structure of the red LED to warp and deform. Summary of the Invention

[0003] In view of this, this application aims to propose an anti-warping GaN red LED epitaxial structure to avoid warping deformation of the red LED epitaxial structure.

[0004] To achieve the above objectives, the technical solution of this application is implemented as follows:

[0005] An anti-warping GaN red LED epitaxial structure includes a substrate, on which a nucleation layer, a buffer layer, a stress relief layer, an N-type GaN layer, a multi-quantum-well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed;

[0006] The substrate is provided with a spherical crown-shaped protrusion;

[0007] Stress relief grooves are formed on the N-type GaN layer, the multi-quantum-well light-emitting layer, the electron blocking layer, and the P-type GaN layer, which are at least partially thick, and the stress relief grooves are filled with filler portions.

[0008] The peak wavelength of the emission from the multi-quantum-well light-emitting layer is between 600nm and 620nm.

[0009] Furthermore, the stress relief groove includes a first groove extending along the length direction of the substrate and a second groove extending along the width direction of the substrate; a plurality of first grooves are provided, and the plurality of first grooves are spaced apart along the width direction of the substrate; a plurality of second grooves are provided, and the plurality of second grooves are spaced apart along the length direction of the substrate.

[0010] Furthermore, the widths of both the first and second grooves are between 1µm and 2µm.

[0011] Furthermore, the stress relief layer includes multiple stress relief sub-layers, with at least 10 stress relief sub-layers stacked sequentially; each stress relief sub-layer includes a lightly doped GaN layer and an n-type heavily doped GaN layer stacked together.

[0012] Furthermore, the thickness of the n-type heavily doped GaN layer is between 70 nm and 100 nm; the thickness of the lightly doped GaN layer is between 30 nm and 50 nm.

[0013] Furthermore, the stress relief layer has a hole covering layer disposed toward the multi-quantum-well light-emitting layer, the hole covering layer being used to cover the holes of the n-type heavily doped GaN layer.

[0014] Furthermore, the pore covering layer is made of GaN material, and the thickness of the pore covering layer is between 1μm and 2μm.

[0015] Furthermore, the filling portion includes a passivation layer disposed on both sides of the stress relief groove and the bottom of the groove, and an optical buffer layer and a planarization layer stacked sequentially on the passivation layer.

[0016] Furthermore, the multi-quantum-well light-emitting layer is composed of alternating InGaN potential well layers and AlGaN barrier layers.

[0017] Furthermore, the monolayer thickness of the InGaN potential well layer of the multi-quantum well light-emitting layer is between 2.4 nm and 2.6 nm; the monolayer thickness of the AlGaN barrier layer of the multi-quantum well light-emitting layer is between 10 nm and 16 nm.

[0018] Compared with related technologies, this application has the following advantages:

[0019] (1) The anti-warping GaN red LED epitaxial structure described in this application is provided with a substrate, on which a nucleation layer, a buffer layer, a stress relief layer, an N-type GaN layer, a multi-quantum-well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially provided. By providing a spherical crown-shaped protrusion on the substrate, some stress can be dissipated near the interface. The stress relief layer absorbs and buffers the lattice mismatch stress transmitted from the upper and lower sides. By opening a stress relief groove, the original large-area continuous active layer can be divided into independent regions. Each region can undergo slight elastic expansion through the sidewall, so that the accumulation of stress loses the continuity condition, which is beneficial to avoid warping deformation of the red LED epitaxial structure.

[0020] (2) The stress relief groove includes a first groove extending along the length direction of the substrate and a second groove extending along the width direction of the substrate. Multiple first grooves are provided and are spaced apart along the width direction of the substrate. Multiple second grooves are provided and are spaced apart along the length direction of the substrate. This can form a grid structure, which helps to make the stress release more uniform throughout the entire surface of the substrate, reduce local warping caused by uneven stress distribution, and further enhance the effect of preventing warping and uniformity.

[0021] (3) By limiting the width of the first and second grooves, the stress release effect can be ensured and the structural strength of each layer can be avoided. At the same time, it can also avoid the reduction of the light-emitting area due to the excessive width of the first or second groove, thus helping to ensure the light-emitting effect.

[0022] (4) The stress relief layer includes multiple sub-stress relief layers with stacked lightly doped GaN layers and n-type heavily doped GaN layers. The number of sub-stress relief layers is limited, which is beneficial to ensure that the stress relief layer has sufficient thickness and energy absorption capacity, thereby ensuring a good stress relief effect, while also facilitating the subsequent processing of porous energy absorption structures.

[0023] (5) By limiting the thickness of the n-type heavily doped GaN layer and the thickness of the lightly doped GaN layer, a nano-network with appropriate porosity can be formed after corrosion. While ensuring high stress release efficiency, the collapse of the layer structure or the difficulty of subsequent epitaxial growth caused by excessive porosity is avoided.

[0024] (6) By setting a hole capping layer facing the multi-quantum well light-emitting layer, the hole capping layer is used to cover the holes of the n-type heavily doped GaN layer, which can provide a continuous and relatively flat growth surface for the subsequent deposition of the multi-quantum well light-emitting layer, which helps to improve the processing quality of the light-emitting layer and also helps to reduce the risk of foreign impurities diffusing along the holes to the active region during subsequent processes or operations.

[0025] (7) By limiting the material and thickness of the pore capping layer, it is possible to avoid the introduction of new lattice mismatch interfaces and associated defects due to different materials, and also to provide sufficient deposition to cover the nanoscale pores on the surface of the stress relief layer, forming a continuous transition layer without through pinholes, providing a reliable growth substrate for the structure above.

[0026] (8) The filling portion includes passivation layers disposed on the side walls and bottom of the stress relief groove, and an optical buffer layer and a planarization layer stacked sequentially on the passivation layers. These layers can protect the side walls and bottom of the stress relief groove, thereby helping to suppress nonradiative recombination and leakage phenomena in the side wall region. The optical buffer layer can alleviate the total internal reflection effect when light exits from the GaN side wall, providing a smoother refractive index transition for light extraction. The planarization layer fills the remaining space of the groove, providing a relatively flat morphology for the chip surface to be compatible with subsequent processes.

[0027] (9) By making the multi-quantum well light-emitting layer alternately composed of InGaN potential well layer and AlGaN potential barrier layer, mutual stress compensation can be achieved in the active region, thereby reducing the net stress level in a single cycle and after multiple cycles, which helps to further alleviate the warping of the epitaxial structure of the epitaxial red LED.

[0028] (10) By limiting the thickness of the InGaN potential well layer of the multi-quantum well light-emitting layer, a strong quantum confinement effect can be formed in the quantum well, which is beneficial to the radiative recombination of charge carriers. By limiting the thickness of the AlGaN barrier layer of the quantum well light-emitting layer, sufficient tensile stress can be provided to compensate for the compressive stress of the potential well layer, while forming an effective barrier height to restrict the escape of charge carriers from the well layer, thus helping to maintain the luminous efficiency while relieving stress. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0030] Figure 1 This is a schematic diagram of the overall structure of the anti-warping GaN red LED epitaxial structure described in the embodiments of this application;

[0031] Figure 2 This is a cross-sectional view of the anti-warping GaN red LED epitaxial structure described in the embodiments of this application;

[0032] Figure 3 This is a schematic diagram of the stress relief groove described in an embodiment of this application;

[0033] Explanation of reference numerals in the attached figures:

[0034] 100. Substrate; 101. Spherical protrusion;

[0035] 200. Nucleation layer;

[0036] 300. Buffer layer;

[0037] 400, Stress relief layer; 401, Partial stress relief layer; 4011, Lightly doped GaN layer; 4012, n-type heavily doped GaN layer; 402, Void capping layer;

[0038] 500, N-type GaN layer;

[0039] 600. Multi-quantum-well light-emitting layer; 601. InGaN potential well layer; 602. AlGaN barrier layer;

[0040] 700, Electron blocking layer;

[0041] 800, P-type GaN layer; 801, First part; 802, Second part;

[0042] 900, Stress relief groove; 901, First groove; 902, Second groove;

[0043] 1000, Filler layer; 1001, Passivation layer; 1002, Optical buffer layer; 1003, Planarization layer. Detailed Implementation

[0044] To make the technical solution and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0046] Furthermore, it should be noted that in the description of this application, if terms such as "upper," "lower," "inner," or "outer" appear, indicating orientation or positional relationship, these are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, if terms such as "first" or "second" appear, they are also used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] Furthermore, in the description of this application, unless otherwise expressly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application in light of the specific circumstances.

[0048] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] The present application will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0050] An embodiment of the first aspect of this application provides an anti-warping GaN red LED epitaxial structure, which is commonly used in red LEDs. Furthermore, the anti-warping GaN red LED epitaxial structure of this application, through structural innovation, can prevent warping of the red LED epitaxial structure.

[0051] In related technologies, GaN-based LED devices with InGaN quantum wells as the active layer are widely used in various fields. However, due to the lack of suitable homogeneous epitaxial substrates, GaN is usually grown on sapphire, silicon carbide, or silicon substrates with significant lattice mismatch. Therefore, traditional GaN-based red LEDs suffer from internal stress during production due to dislocation defects formed between GaN and the substrate, causing warping and deformation of the entire red LED epitaxial structure.

[0052] In view of this, in order to overcome the shortcomings of related technologies, the anti-warping GaN red LED epitaxial structure of this embodiment combines... Figures 1 to 3 As shown, the overall design includes a substrate 100, on which a nucleation layer 200, a buffer layer 300, a stress relief layer 400, an N-type GaN layer 500, a multi-quantum-well light-emitting layer 600, an electron blocking layer 700, and a P-type GaN layer 800 are sequentially disposed.

[0053] The substrate 100 has a spherical protrusion 101. Stress relief grooves 900 are formed on at least a partially thick N-type GaN layer 500, a multi-quantum-well emitting layer 600, an electron-blocking layer 700, and a partially thick P-type GaN layer 800. The stress relief grooves 900 are filled with filler portions 1000. The emission peak wavelength of the multi-quantum-well emitting layer 600 is between 600 nm and 620 nm.

[0054] Therefore, by setting a substrate 100, on which a nucleation layer 200, a buffer layer 300, a stress relief layer 400, an N-type GaN layer 500, a multi-quantum-well light-emitting layer 600, an electron blocking layer 700, and a P-type GaN layer 800 are sequentially provided, and by setting a spherical protrusion 101 on the substrate 100, some stress can be dissipated near the interface, while the stress relief layer 400 absorbs and buffers the lattice mismatch stress transmitted from the upper and lower sides, and by opening a stress relief groove 900, the originally large-area continuous active layer can be divided into independent regions, and each region can undergo slight elastic expansion through the sidewalls, so that the accumulation of stress loses the continuous condition, which is beneficial to avoid warping and deformation of the epitaxial structure of the red LED.

[0055] Based on the above overview, specifically, the substrate 100 in this embodiment typically uses a sapphire substrate 100, which is well-known to those skilled in the art. This substrate possesses good light transmittance, a good crystal structure, and thermal stability, thereby ensuring the overall structural stability while maintaining the light emission performance of the LED. Furthermore, the sapphire substrate 100 also exhibits good chemical inertness and process compatibility, facilitating the growth of epitaxial structures.

[0056] The spherical protrusion 101 disposed on the sapphire substrate 100 preferably has a duty cycle of 50% to provide a better stress relief effect. Of course, it is not limited to this. The spherical protrusion 101 in this embodiment can also be selected in other shapes according to specific circumstances, such as spherical protrusion 101, hexagonal pyramid, micro pyramid array, etc., as long as it can meet the usage requirements.

[0057] The nucleation layer 200 mentioned above is typically made of GaN or AlN deposited at low temperature, with a thickness generally between 15nm and 50nm. A preferred thickness is, for example, 25nm, to facilitate the formation of a continuous and uniform nucleation layer 200 while avoiding its impact on the subsequent single crystal quality. Of course, its thickness can be adapted to meet specific requirements.

[0058] Furthermore, the aforementioned buffer layer 300 can be made of unintentionally doped GaN (u-GaN), as is well known to those skilled in the art, to provide a substrate with low dislocation density and high crystal quality for subsequent epitaxial layers. The thickness of the buffer layer 300 is generally between 1.5 μm and 4.0 μm, preferably 2 μm, to ensure sufficient thickness while facilitating manufacturing. Of course, its thickness can be adapted to meet specific requirements.

[0059] The aforementioned electron blocking layer 700 is typically made of magnesium-doped p-type AlGaN (p-AlGaN) to block carrier leakage, thereby improving luminous efficiency. The thickness of the electron blocking layer 700 is generally between 15 nm and 30 nm, with a preferred thickness of, for example, 20 nm. Of course, its thickness can be adapted to meet specific requirements.

[0060] Furthermore, for ease of description, the stress relief groove 900 provided on the N-type GaN layer 500 is the first stress relief groove 900, the stress relief groove 900 provided on the multi-quantum-well light-emitting layer 600 is the second stress relief groove 900, the stress relief groove 900 provided on the electron blocking layer 700 is the third stress relief groove 900, and the stress relief groove 900 provided on the P-type GaN layer 800 is the fourth stress relief groove 900. The aforementioned first stress relief groove 900, second stress relief groove 900, third stress relief groove 900, and fourth stress relief groove 900 are all provided in a one-to-one correspondence to facilitate production and processing.

[0061] The stress relief groove 900 formed on at least a portion of the thickness of the N-type GaN layer 500 can ensure the stress relief effect of the stress relief groove 900 while maintaining the lateral conductive continuity of the N-type GaN layer 500, so as to facilitate subsequent processes. The aforementioned P-type GaN layer 800 includes a first portion 801 and a second portion 802. The stress relief groove 900 is formed on the first portion 801 to ensure stress relief and facilitate processing, while the second portion 802 is used to maintain the lateral conductive continuity of the P-type GaN layer 800, so as to facilitate subsequent processes.

[0062] In addition, it is worth mentioning that any related structures not mentioned in this embodiment can be referred to as related structures well known to those skilled in the art, and will not be described in detail here.

[0063] Combination Figure 1 and Figure 3 As shown, in some exemplary embodiments, the stress relief groove 900 includes a first groove 901 extending along the length direction of the substrate 100 and a second groove 902 extending along the width direction of the substrate 100. A plurality of first grooves 901 are provided, and the plurality of first grooves 901 are spaced apart along the width direction of the substrate 100. A plurality of second grooves 902 are provided, and the plurality of second grooves 902 are spaced apart along the length direction of the substrate 100.

[0064] This configuration creates a mesh-like structure, which helps to distribute stress more evenly across the entire surface of the substrate 100, reducing local warping caused by uneven stress distribution and further enhancing the warping prevention effect and uniformity.

[0065] In specific implementation, the first groove 901 in this embodiment can be, for example, six spaced apart along its width, to ensure structural reliability while providing good stress relief. Of course, the specific number of the first groove 901 can be adjusted according to actual needs, as long as it meets the usage requirements; further details will not be elaborated here.

[0066] Furthermore, the first groove 901 and the second groove 902 in this embodiment can be, for example, five spaced apart along the length direction, to ensure structural reliability while providing good stress relief. Of course, the specific number of the second groove 902 can be adjusted adaptively according to actual needs, as long as it meets the usage requirements.

[0067] Combination Figure 2 As shown, in some exemplary embodiments, the widths of both the first groove 901 and the second groove 902 are between 1µm and 2µm. This arrangement ensures stress relief and avoids weakening the structural strength of each layer. Simultaneously, it also prevents a reduction in the light-emitting area due to excessive width of the first groove 901 or the second groove 902, thereby contributing to ensuring the light-emitting effect.

[0068] In practical implementation, the first groove 901 and the second groove 902 can be selected to have the same width, such as 1μm or 1.5μm, in order to reduce the weakening of structural strength while having sufficient stress release capability. At the same time, it can also facilitate the subsequent process.

[0069] Of course, the first groove 901 and the second groove 902 can be selected with different widths, such as the first groove 901 being 1μm wide or the second groove 902 being 2μm wide. This selection is suitable for scenarios where the stress release requirements in the two directions are asymmetrical. It should be noted that the widths of the first groove 901 and the second groove 902 can be adaptively adjusted according to the actual situation, as long as the usage requirements are met, which will not be elaborated further here.

[0070] Continue to combine Figure 2 As shown, in some exemplary embodiments, the stress relief layer 400 includes a plurality of sub-stress relief layers 401, with at least 10 sub-stress relief layers 401 stacked sequentially. Each sub-stress relief layer 401 includes a lightly doped GaN layer 4011 and an n-type heavily doped GaN layer 4012 stacked together.

[0071] The advantage of this design is that it ensures that the stress relief layer 400 has sufficient thickness and energy absorption capacity, thereby ensuring a good stress relief effect, while also facilitating the subsequent processing of porous energy absorption structures.

[0072] In specific implementation, for example, 12 stress relief layers 401 can be selected to achieve better stress absorption efficiency and structural stability. This also allows for better control of process time. Of course, the specific number of stress relief layers 401 in this embodiment can be adjusted according to actual needs, which will not be elaborated further here.

[0073] Furthermore, the Si doping concentration of the aforementioned n-type heavily doped GaN layer 4012 is 1×10¹. 9 atoms / cm³ - 5×10¹ 9 The Si doping concentration is set at atoms / cm³ to achieve good processing performance while avoiding lattice distortion that could introduce additional internal stress. A preferred Si doping concentration is, for example, 3 × 10¹. 9 atoms / cm³, of course, the specific value can be adjusted according to the actual situation, as long as it can meet the usage requirements.

[0074] The lightly doped GaN layer 4011 mentioned above has a Si doping concentration of 1×10¹. 7 atoms / cm³ - 3×10¹ 7 The Si doping concentration is set at atoms / cm³ to achieve both good processability and stability. For example, a Si doping concentration of 2 × 10¹ is preferably preferred. 9 atoms / cm³, of course, the specific value can be adjusted according to the actual situation, as long as it can meet the usage requirements, and will not be elaborated here.

[0075] Combination Figure 2 As shown, in some exemplary embodiments, the thickness of the heavily doped n-type GaN layer 4012 is between 70 nm and 100 nm. The thickness of the lightly doped GaN layer 4011 is between 30 nm and 50 nm. This allows for the formation of a nanonetwork with appropriate porosity after etching, ensuring high stress release efficiency while avoiding layer structure collapse or difficulties in subsequent epitaxial growth due to excessive porosity.

[0076] In practical implementation, the thickness of the aforementioned heavily doped n-type GaN layer 4012 is preferably 80nm, 100nm, or 70nm, to achieve both good stress relief efficiency and good structural integrity. Of course, the thickness of the heavily doped n-type GaN layer 4012 can also be adjusted adaptively according to actual needs, as long as the requirements are met.

[0077] Furthermore, corresponding to the thickness of the heavily doped n-type GaN layer 4012 mentioned above, the thickness of the lightly doped GaN layer 4011 can preferably be 40 nm, 50 nm, or 50 nm. That is, when the thickness of the heavily doped n-type GaN layer 4012 is 80 nm, the thickness of the lightly doped GaN layer 4011 is selected as 40 nm. This maintains a continuous and dense single-crystal framework, thereby ensuring support reliability. Of course, the thickness of the lightly doped GaN layer 4011 can also be adjusted adaptively according to actual conditions, as long as the usage requirements are met.

[0078] Similarly combined Figures 1 to 2 As shown, in some exemplary embodiments, the stress relief layer 400 has a hole capping layer 402 disposed toward the multi-quantum-well light-emitting layer 600, the hole capping layer 402 being used to cover the holes of the n-type heavily doped GaN layer 4012.

[0079] This provides a continuous and relatively flat growth surface for the subsequent deposition of the multi-quantum-well light-emitting layer 600, which helps improve the processing quality of the light-emitting layer and also helps reduce the risk of foreign impurities diffusing along the holes into the active region during subsequent processes or operations.

[0080] Continue to combine Figures 1 to 3 As shown, in some exemplary embodiments, the hole capping layer 402 is made of GaN material, and the thickness of the hole capping layer 402 is between 1 μm and 2 μm.

[0081] In this way, new lattice mismatch interfaces and associated defects caused by the introduction of different materials can be avoided, and sufficient deposition can be provided to cover the pores on the surface of the stress relief layer 400, forming a continuous transition layer without through pinholes, providing a reliable growth substrate for the structure above.

[0082] In specific implementation, the thickness of the aforementioned pore capping layer 402 is preferably 1 μm to provide sufficient deposition to cover the nanoscale pores on the surface of the stress relief layer 400 while avoiding the introduction of additional film stress. Of course, the thickness of the pore capping layer 402 can also be adjusted adaptively according to actual conditions, as long as the usage requirements are met.

[0083] Combination Figure 3 As shown, in some exemplary embodiments, the filling portion 1000 includes a passivation layer 1001 disposed on both side walls and the bottom of the stress relief groove 900, and an optical buffer layer 1002 and a planarization layer 1003 sequentially stacked on the passivation layer 1001.

[0084] This design protects the sidewalls and bottom of the stress relief groove 900, helping to suppress nonradiative recombination and leakage in the sidewall region. The optical buffer layer 1002 alleviates the total internal reflection effect when light exits from the GaN sidewalls, providing a smoother refractive index transition for light extraction. The planarization layer 1003 fills the remaining space of the groove, providing a relatively flat morphology for the chip surface to be compatible with subsequent processes.

[0085] In specific implementation, the passivation layer 1001 mentioned above can be made of aluminum oxide (Al2O3), which is well known to those skilled in the art. It is dense and free of pinholes, and chemically inert, which is beneficial for protecting the two side walls and the bottom of the stress relief groove 900.

[0086] Furthermore, the aforementioned optical buffer layer 1002 can be made of silicon dioxide (SiO2), which is well known to those skilled in the art. The amorphous silicon dioxide thin film deposited by PECVD (Plasma-Enhanced Chemical Vapor Deposition) can play a role in the refractive index gradient transition, effectively reducing the total internal reflection angle when light is emitted from GaN and improving the light extraction efficiency.

[0087] In addition, the planarization layer 1003 mentioned above can be made of benzocyclobutene (BCB), i.e. (C8H8). n The polymer base possesses both good leveling properties and good flexibility, thus facilitating processing and molding while also exhibiting good stress absorption capabilities. Simultaneously, it also possesses good light transmittance, which helps ensure light extraction efficiency.

[0088] It should be noted that the passivation layer 1001, the optical buffer layer 1002, and the planarization layer 1003 can all be made of other materials known to those skilled in the art, as long as they meet the usage requirements.

[0089] Combination Figure 2 As shown, in some exemplary embodiments, the multi-quantum-well light-emitting layer 600 is composed of alternating InGaN potential well layers 601 and AlGaN barrier layers 602. The advantage of this arrangement is that it enables mutual stress compensation within the active region, reducing the net stress level within a single cycle and after accumulation over multiple cycles, thereby helping to further mitigate the warpage of the epitaxial structure of the epitaxial red LED.

[0090] In practical implementation, specifically, the InGaN well layer 601 mentioned above is made of InGaN (indium gallium nitride), which is a mixed crystal of GaN and InN. To make the LED emit red light at 600-620 nm, the indium content in InGaN needs to be increased to 30%-40%. The lattice constant of high indium content InGaN is larger than that of GaN. When it is grown as a thin film on the GaN lattice, its atomic spacing is forced to compress to fit the underlying lattice, thereby accumulating compressive stress inside the active region.

[0091] In contrast, the AlGaN barrier layer has a smaller lattice constant than GaN and is subjected to tensile stress during growth. When the multi-quantum-well light-emitting layer 600 is composed of alternating InGaN potential well layers 601 and AlGaN barrier layers 602, the stress directions of the two layers are opposite, thereby enabling control of the stress in the multi-quantum-well light-emitting layer 600.

[0092] In some exemplary embodiments, the monolayer thickness of the InGaN potential well layer 601 of the multi-quantum-well emitting layer 600 is between 2.4 nm and 2.6 nm. The monolayer thickness of the AlGaN barrier layer 602 of the multi-quantum-well emitting layer 600 is between 10 nm and 16 nm. Thus, by limiting the monolayer thickness of the InGaN potential well layer 601 of the multi-quantum-well emitting layer 600, a strong quantum confinement effect can be formed in the quantum well, which is beneficial to the radiative recombination of charge carriers. By limiting the monolayer thickness of the AlGaN barrier layer 602 of the quantum well emitting layer, sufficient tensile stress can be provided to compensate for the compressive stress of the potential well layer, while forming an effective barrier height to restrict the escape of charge carriers from the well layer, thereby helping to maintain luminescence efficiency while relieving stress.

[0093] In specific implementation, the thickness of a single InGaN potential well layer 601 of the multi-quantum well light-emitting layer 600 in this embodiment is preferably 2.5 nm, 2.6 nm, or 2.4 nm to ensure the emission peak wavelength and improve luminous efficiency. Of course, the thickness of a single InGaN potential well layer 601 can also be adjusted adaptively according to actual conditions, which will not be elaborated here.

[0094] Furthermore, the thickness of the AlGaN barrier layer 602 is preferably 12 nm, 14 nm, or 11 nm to provide sufficient tensile stress in the AlGaN barrier, thereby effectively neutralizing the pressure of the well layer. Of course, the thickness of the AlGaN barrier layer 602 can also be adjusted adaptively according to actual conditions, as long as the application requirements are met.

[0095] It is worth noting that, regarding the anti-warpage GaN red LED epitaxial structure of this embodiment, based on the above exemplary embodiments, in specific implementation, as a preferred embodiment, it is still composed of... Figures 1 to 3 As shown, it may include, for example, a substrate 100, on which a nucleation layer 200, a buffer layer 300, a stress relief layer 400, an N-type GaN layer 500, a multi-quantum-well light-emitting layer 600, an electron blocking layer 700, and a P-type GaN layer 800 are sequentially disposed.

[0096] The substrate 100 has a spherical protrusion 101. Stress relief grooves 900 are formed on at least a portion of the thickness of the N-type GaN layer 500, the multi-quantum-well light-emitting layer 600, the electron-blocking layer 700, and the at least a portion of the thickness of the P-type GaN layer 800. The stress relief grooves 900 are filled with filler portions 1000. The emission peak wavelength of the multi-quantum-well light-emitting layer 600 is between 600 nm and 620 nm.

[0097] The stress relief groove 900 includes a first groove 901 extending along the length direction of the substrate 100 and a second groove 902 extending along the width direction of the substrate 100. Multiple first grooves 901 are provided, and the multiple first grooves 901 are spaced apart along the width direction of the substrate 100. Multiple second grooves 902 are provided, and the multiple second grooves 902 are spaced apart along the length direction of the substrate 100. The width of both the first groove 901 and the second groove 902 is 1µm.

[0098] The stress relief layer 400 includes multiple stress relief sub-layers 401, with at least 10 stress relief sub-layers 401 stacked sequentially. Each stress relief sub-layer 401 includes a lightly doped GaN layer 4011 and an n-type heavily doped GaN layer 4012 stacked together. The thickness of the n-type heavily doped GaN layer 4012 is 80 nm. The thickness of the lightly doped GaN layer 4011 is 40 nm. The stress relief layer 400 has a hole capping layer 402 disposed towards the multi-quantum well light-emitting layer 600, which covers the holes in the n-type heavily doped GaN layer 4012.

[0099] The perforated layer 402 is made of GaN material, and its thickness is between 1 μm. The filling portion 1000 includes a passivation layer 1001 disposed on both side walls and the bottom of the stress relief groove 900, and an optical buffer layer 1002 and a planarization layer 1003 sequentially stacked on the passivation layer 1001. The multi-quantum-well light-emitting layer 600 is composed of alternating InGaN potential well layers 601 and AlGaN barrier layers 602. The single-layer thickness of the InGaN potential well layer 601 in the multi-quantum-well light-emitting layer 600 is 2.5 nm. The single-layer thickness of the AlGaN barrier layer 602 in the multi-quantum-well light-emitting layer 600 is 12 nm.

[0100] In the preferred embodiment of the above anti-warping GaN red LED epitaxial structure, the specific settings and arrangements of the stress relief layer 400, the multi-quantum well light-emitting layer 600, the stress relief groove 900, etc., can still be referred to the descriptions in the above exemplary embodiments. Furthermore, in this preferred embodiment, the beneficial effects brought about by the design of the stress relief layer 400 and the stress relief groove 900, etc., can also be referred to the descriptions in the above exemplary embodiments.

[0101] The anti-warpage GaN red LED epitaxial structure of this application is specifically formed as follows: First, a sapphire substrate 100 is provided, and periodically arranged spherical protrusions 101 are formed on the surface of the substrate 100 by photolithography and ICP dry etching. Then, a nucleation layer 200 and a buffer layer 300 are sequentially grown on the substrate 100 in MOCVD. The nucleation layer 200 is low-temperature GaN or AlN. The buffer layer 300 is unintentionally doped GaN, with dislocation density reduced through high-temperature lateral merging.

[0102] Next, a stress-relieving layer 400 is grown on the buffer layer 300. This layer consists of 10 pairs of alternately stacked n-type heavily doped GaN layers 4012 and lightly doped GaN layers 4011. The heavily doped layers are selectively removed by electrochemical etching to form a nanoporous structure. The lightly doped layers are retained as a dense single-crystal framework. Subsequently, a GaN pore capping layer 402 is grown on the stress-relieving layer 400 to seal surface pores and provide a flat growth substrate.

[0103] Then, an N-type GaN layer 500 is grown on the hole capping layer 402 as an electron injection layer and a common conductive channel. A multi-quantum-well emitting layer 600, consisting of alternating InGaN potential well layers 601 and AlGaN barrier layers 602, is grown on the N-type GaN layer 500. A high indium composition ensures the emission peak wavelength falls within the 600-620 nm range. An electron blocking layer 700 and a P-type GaN layer 800 are then sequentially grown on the multi-quantum-well emitting layer 600.

[0104] Finally, through photolithography and ICP dry etching, a grid-like stress relief trench 900 is formed downwards from the surface of the P-type GaN layer 800, sequentially penetrating the P-type GaN layer 800, the electron blocking layer 700, the multi-quantum-well light-emitting layer 600, and extending into the interior of the N-type GaN layer 500. After repairing the trench sidewalls, a passivation layer 1001 and an optical buffer layer 1002 are sequentially deposited and planarized. The second portion 802 of the P-type GaN layer 800 is deposited on the planarized surface to facilitate the uniform formation of P-electrode interconnects or common anode driving structures, and can also serve as a current spreading layer for uniformly injecting holes.

[0105] The anti-warping GaN red LED epitaxial structure of this embodiment adopts the above design. By setting a substrate 100, a nucleation layer 200, a buffer layer 300, a stress relief layer 400, an N-type GaN layer 500, a multi-quantum-well light-emitting layer 600, an electron blocking layer 700, and a P-type GaN layer 800 are sequentially provided on the substrate 100. By setting a spherical crown-shaped protrusion 101 on the substrate 100, some stress can be dissipated near the interface. The stress relief layer 400 absorbs and buffers the lattice mismatch stress transmitted from the upper and lower sides. By opening a stress relief groove 900, the originally large-area continuous active layer can be divided into independent regions. Each region can undergo slight elastic expansion through the sidewalls, so that the accumulation of stress loses the continuity condition, which helps to avoid warping deformation of the red LED epitaxial structure.

[0106] The above descriptions are merely some embodiments of this application and are not intended to limit this application. The technical features or structures in the foregoing different embodiments can be arbitrarily combined to form other specific technical solutions as needed. For those skilled in the art, this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of the claims of this application.

Claims

1. A warp-resistant GaN red LED epitaxial structure, characterized in that: Includes a substrate (100), on which a nucleation layer (200), a buffer layer (300), a stress relief layer (400), an N-type GaN layer (500), a multi-quantum-well light-emitting layer (600), an electron blocking layer (700), and a P-type GaN layer (800) are sequentially disposed. The substrate (100) is provided with a spherical protrusion (101). Stress relief grooves (900) are formed on the N-type GaN layer (500) with at least a partial thickness, the multi-quantum well light-emitting layer (600), the electron blocking layer (700), and the P-type GaN layer (800) with at least a partial thickness, and the stress relief grooves (900) are filled with filling portions (1000). The peak emission wavelength of the multi-quantum-well light-emitting layer (600) is between 600nm and 620nm.

2. The anti-warping GaN red LED epitaxial structure according to claim 1, characterized in that: The stress relief groove (900) includes a first groove (901) extending along the length direction of the substrate (100) and a second groove (902) extending along the width direction of the substrate (100). Multiple first grooves (901) are provided, and the multiple first grooves (901) are spaced apart along the width direction of the substrate (100); Multiple second grooves (902) are provided, and the multiple second grooves (902) are spaced apart along the length direction of the substrate (100).

3. The anti-warping GaN red LED epitaxial structure according to claim 2, characterized in that: The widths of the first groove (901) and the second groove (902) are both between 1µm and 2µm.

4. The anti-warping GaN red LED epitaxial structure according to claim 1, characterized in that: The stress relief layer (400) includes a plurality of sub-stress relief layers (401), and at least 10 of the sub-stress relief layers (401) are stacked sequentially; Each of the stress relief layers (401) comprises a lightly doped GaN layer (4011) and an n-type heavily doped GaN layer (4012) arranged in a stacked manner.

5. The anti-warping GaN red LED epitaxial structure according to claim 4, characterized in that: The thickness of the n-type heavily doped GaN layer (4012) is between 70 nm and 100 nm; The thickness of the lightly doped GaN layer (4011) is between 30 nm and 50 nm.

6. The anti-warping GaN red LED epitaxial structure according to claim 4, characterized in that: The stress relief layer (400) has a hole capping layer (402) disposed toward the multi-quantum well light-emitting layer (600), the hole capping layer (402) being used to cover the holes of the n-type heavily doped GaN layer (4012).

7. The anti-warping GaN red LED epitaxial structure according to claim 6, characterized in that: The pore covering layer (402) is made of GaN material, and the thickness of the pore covering layer (402) is between 1μm and 2μm.

8. The anti-warping GaN red LED epitaxial structure according to claim 1, characterized in that: The filling portion (1000) includes a passivation layer (1001) disposed on both sides of the stress relief groove (900) and the bottom of the groove, and an optical buffer layer (1002) and a planarization layer (1003) stacked sequentially on the passivation layer (1001).

9. The anti-warping GaN red LED epitaxial structure according to claim 1, characterized in that: The multi-quantum-well light-emitting layer (600) is composed of alternating InGaN potential well layers (601) and AlGaN potential barrier layers (602).

10. The anti-warping GaN red LED epitaxial structure according to claim 9, characterized in that: The thickness of the InGaN potential well layer (601) of the multi-quantum well light-emitting layer (600) is between 2.4 nm and 2.6 nm. The single-layer thickness of the AlGaN barrier layer (602) of the multi-quantum well light-emitting layer (600) is between 10 nm and 16 nm.

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