Composite Si / Al insertion layer structure and its preparation method and application

Abstract

The present invention discloses a composite Si / Al insertion layer structure, a preparation method thereof, and an application thereof. The composite Si / Al insertion layer structure comprises: a SiN film layer, an AlN filling layer, and an AlN film layer, wherein the AlN filling layer is spaced apart within the SiN film layer, and the AlN film layer is stacked on the SiN film layer and the AlN filling layer; and, a plurality of AlN microstructures are further provided within the SiN film layer, and a plurality of SiN microstructures are further provided within the AlN film layer. The present invention overcomes the problem of poor uniformity in the growth of large-scale Micro-LED epitaxial quantum wells, is suitable for large-scale long-wave emission, and greatly improves the brightness and luminous efficiency of Micro-LED epitaxial wafers.

Description

Technical Field

[0001] The present invention particularly relates to a composite Si / Al insertion layer structure and a preparation method and application thereof, belonging to the technical field of semiconductor devices. Background Art

[0002] Micro-LED is composed of an array of micron-scale semiconductor light-emitting units. The development of Micro-LED is considered to be one of the fastest-growing display technologies in the world. Due to its advantages such as small size, high resolution, low energy consumption and high reliability, it is widely used in various fields such as visible light communication applications, large flat-panel displays, virtual reality and wearable displays, televisions and lighting, optogenetics and neural interface light sources.

[0003] Despite its promising development prospects, Micro-LEDs still face several technical challenges that need to be addressed to achieve large-scale commercialization. Currently, III-nitride Micro-LEDs are typically fabricated using a combination of standard photolithography and dry etching. However, dry etching of the epitaxial structure inevitably causes surface damage to the Micro-LED chip, increasing the surface non-radiative recombination rate, reducing the internal quantum efficiency, and thus the chip's external quantum efficiency. Due to the small size of Micro-LEDs, which have a larger surface-to-volume ratio than large-scale LED chips, the surface damage caused by dry etching has a more significant impact on the chip's optoelectronic performance, severely impacting its luminous efficiency. Furthermore, with the development of markets such as semiconductor lighting and displays, demand for substrates is increasingly shifting towards larger sizes. Warping caused by residual stress in the epitaxial layer on large-scale substrates is a difficult problem to overcome with epitaxial technology. This poses a particular challenge to the high uniformity required for Micro-LED epitaxial wafers, which is crucial for achieving technological advancements and industrial applications.

[0004] Therefore, how to realize the preparation of Micro-LED epitaxial wafers on large-size substrates is of great significance to accelerating the industrial application of Micro-LED, and it is still a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] The main purpose of the present invention is to provide a composite Si / Al insertion layer structure and a preparation method and application thereof, thereby overcoming the deficiencies in the prior art.

[0006] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0007] A first aspect of the present invention provides a composite Si / Al insertion layer structure, comprising: a SiN film layer, an AlN filling layer, and an AlN film layer, wherein the AlN filling layer is spaced apart within the SiN film layer, and the AlN film layer is stacked on the SiN film layer and the AlN filling layer; and, a plurality of AlN microstructures are further disposed within the SiN film layer, and a plurality of SiN microstructures are further disposed within the AlN film layer.

[0008] A second aspect of the present invention provides a method for preparing a composite Si / Al insertion layer structure, comprising:

[0009] Providing a Si atom-rich SiN film layer, wherein a selected surface of the SiN film layer has a plurality of nanopore structures;

[0010] Growing AlN in the nanopore structure to form;

[0011] forming an Al layer on a selected surface of the SiN film layer, wherein the Al layer also covers the SiN film layer, thereby forming a composite Si / Al insertion layer structure precursor;

[0012] The composite Si / Al insertion layer structure precursor is heat-treated in an environment with a nitrogen source, so that part of the Al atoms in the Al layer and the surplus Si atoms in the SiN film layer are mutually dissolved and diffused, and the Al atoms and Si atoms in the composite Si / Al insertion layer structure precursor are respectively combined with the N atoms provided by the nitrogen source to form AlN and SiN, wherein a part of the AlN formed by the heat treatment is stacked on the upper surface of the SiN film layer to form an AlN film layer, and another part of the AlN is distributed inside the SiN film layer to form a plurality of AlN microstructures. The SiN formed by the heat treatment is distributed inside the AlN film layer to form a plurality of SiN microstructures, thereby forming a composite Si / Al insertion layer structure.

[0013] The third aspect of the present invention provides a quantum well structure, comprising at least one quantum well layer and at least one quantum barrier layer stacked in sequence along a selected direction, wherein the quantum barrier layer comprises at least two barrier layers stacked along the selected direction and at least one composite insertion layer, wherein at least one composite insertion layer is arranged between two adjacent barrier layers, and the composite insertion layer comprises the composite Si / Al insertion layer structure.

[0014] A fourth aspect of the present invention provides an epitaxial wafer, which includes the quantum well structure.

[0015] Compared with the existing technology, the advantages of the present invention include: the present invention overcomes the problem of poor growth uniformity of large-size Micro-LED epitaxial quantum wells, is suitable for large-size long-wave emission, and greatly improves the brightness and luminous efficiency of Micro-LED epitaxial wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic structural diagram of a nitride light-emitting layer provided in a typical embodiment of the present invention;

[0017] Figure 2 1 is a schematic structural diagram of a composite insert layer provided in a typical embodiment of the present invention;

[0018] Figure 3 This is an electron microscope image of a composite insertion layer provided in a typical embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of a preparation process of a nitride light-emitting layer provided in a typical embodiment of the present invention;

[0020] Figure 5 This is a schematic diagram of the preparation process of a composite insertion layer in a nitride light-emitting layer provided in a typical embodiment of the present invention;

[0021] Figure 6 This is a schematic structural diagram of the composite insertion layer in Comparative Example 1. DETAILED DESCRIPTION

[0022] In view of the shortcomings of the prior art, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of the present invention. The following will further explain this technical solution, its implementation process and principles.

[0023] A first aspect of the present invention provides a composite Si / Al insertion layer structure, comprising: a SiN film layer, an AlN filling layer, and an AlN film layer, wherein the AlN filling layer is spaced apart within the SiN film layer, and the AlN film layer is stacked on the SiN film layer and the AlN filling layer; and, a plurality of AlN microstructures are further disposed within the SiN film layer, and a plurality of SiN microstructures are further disposed within the AlN film layer.

[0024] Furthermore, the SiN film layer has a plurality of nanopore structures, and the AlN filling layer is arranged in the nanopore structures.

[0025] Furthermore, the nanopore structure is a through-hole structure that penetrates along the thickness direction of the SiN film layer, and the surface of the AlN filling layer is flush with the surface of the SiN film layer.

[0026] Furthermore, the AlN microstructure and the AlN film layer are integrated.

[0027] Furthermore, the SiN microstructure and the SiN film layer are integrated.

[0028] Furthermore, the thicknesses of the SiN film layer, the AlN filling layer and the AlN film layer are all in the nanometer scale.

[0029] Furthermore, the SiN film layer and the AlN filling layer have the same thickness.

[0030] A second aspect of the present invention provides a method for preparing a composite Si / Al insertion layer structure, comprising:

[0031] Providing a Si atom-rich SiN film layer, wherein a selected surface of the SiN film layer has a plurality of nanopore structures;

[0032] Growing AlN in the nanopore structure to form an AlN filling layer;

[0033] forming an Al layer on a selected surface of the SiN film layer, wherein the Al layer also covers the AlN filling layer, thereby forming a composite Si / Al insertion layer structure precursor;

[0034] The composite Si / Al insertion layer structure precursor is heat-treated in an environment with a nitrogen source, so that part of the Al atoms in the Al layer and the surplus Si atoms in the SiN film layer are mutually dissolved and diffused, and the Al atoms and Si atoms in the composite Si / Al insertion layer structure precursor are respectively combined with the N atoms provided by the nitrogen source to form AlN and SiN, wherein a part of the AlN formed by the heat treatment is stacked on the upper surface of the SiN film layer to form an AlN film layer, and another part of the AlN is distributed inside the SiN film layer to form a plurality of AlN microstructures. At least a part of the SiN formed by the heat treatment is distributed inside the AlN film layer to form a plurality of SiN microstructures, thereby forming a composite Si / Al insertion layer structure.

[0035] Furthermore, the surface is flush with the selected surface of the SiN film layer.

[0036] Furthermore, the thickness is the same as the thickness of the SiN film layer.

[0037] Furthermore, the nanopore structure is a through hole that penetrates along the thickness direction of the SiN film layer.

[0038] Furthermore, the nanopore structure is formed by the discontinuous membrane structure of the SiN membrane layer itself.

[0039] In a typical embodiment, the method for preparing the composite Si / Al insertion layer structure specifically includes:

[0040] Growing a SiN film rich in Si atoms under a first temperature and a first pressure, wherein a selected surface of the SiN film has a plurality of nanopore structures penetrating along the thickness direction of the SiN film;

[0041] Under second temperature and second pressure conditions, growing AlN in the nanopore structure of the SiN membrane layer, filling the nanopore structure with AlN, and forming an AlN filling layer, wherein the surface of the AlN filling layer is flush with the selected surface of the SiN membrane layer;

[0042] forming an Al layer on a selected surface of the SiN film layer under a third temperature and a third pressure condition, wherein the Al layer also covers the AlN filling layer, thereby forming a composite Si / Al insertion layer structure precursor;

[0043] Under fourth temperature and fourth pressure conditions, the composite Si / Al insertion layer structure precursor is heat-treated in an environment with a nitrogen source, so that part of the Al atoms in the Al layer and the surplus Si atoms in the SiN film layer are mutually dissolved and diffused, and the Al atoms and Si atoms in the composite Si / Al insertion layer structure precursor are respectively combined with the N atoms provided by the nitrogen source to form AlN and SiN, wherein a part of the AlN formed by the heat treatment is stacked on the upper surface of the SiN film layer to form an AlN film layer, and another part of the AlN is distributed inside the SiN film layer to form a plurality of AlN microstructures. At least a part of the SiN formed by the heat treatment is distributed inside the AlN film layer to form a plurality of SiN microstructures, thereby forming a composite Si / Al insertion layer structure.

[0044] Furthermore, the first temperature is 1000° C. to 1200° C., and the first pressure is 200 torr to 600 torr.

[0045] Furthermore, the second temperature is 1000° C. to 1200° C., and the second pressure is 100 torr to 300 torr.

[0046] Furthermore, the third temperature is 950° C. to 1000° C., and the third pressure is 50 torr to 200 torr.

[0047] Furthermore, the fourth temperature is 1000° C. to 1200° C., and the fourth pressure is 200 torr to 400 torr.

[0048] Furthermore, the heat treatment time is 5s~20s.

[0049] Furthermore, the thickness of the SiN film layer is 2nm~8nm.

[0050] Furthermore, the thickness of the AlN filling layer is 2nm~8nm.

[0051] Furthermore, the thickness of the Al layer is 2nm~5nm.

[0052] The third aspect of the present invention provides a quantum well structure, comprising at least one quantum well layer and at least one quantum barrier layer stacked in sequence along a selected direction, wherein the quantum barrier layer comprises at least two barrier layers stacked along the selected direction and at least one composite insertion layer, wherein at least one composite insertion layer is arranged between two adjacent barrier layers, and the composite insertion layer comprises the composite Si / Al insertion layer structure.

[0053] Furthermore, the composite insertion layer includes a plurality of composite Si / Al insertion layer structures periodically and repeatedly stacked along the selected direction.

[0054] Furthermore, the quantum barrier layer includes a first barrier layer, a second barrier layer, and a third barrier layer stacked along the selected direction, and the composite insertion layer is stacked between the second barrier layer and at least one of the first barrier layer and the third barrier layer.

[0055] Furthermore, the quantum well layer and the quantum barrier layer are periodically and repeatedly stacked.

[0056] Furthermore, the quantum well layer and the quantum barrier layer are both made of nitride.

[0057] Furthermore, the quantum well layer and the quantum barrier layer are both made of Group III nitride.

[0058] A fourth aspect of the present invention provides an epitaxial wafer, which includes the quantum well structure.

[0059] Furthermore, the epitaxial wafer includes a Micro-LED epitaxial wafer, and the quantum well structure serves as a light-emitting layer of the Micro-LED epitaxial wafer.

[0060] The technical solution, its implementation process and principles will be further explained below in conjunction with the accompanying drawings and specific implementation cases. Unless otherwise specified, the semiconductor epitaxial growth, metal deposition, nitrogen heat treatment processes and equipment used in the embodiments of the present invention are well known to those skilled in the art and are not specifically limited or described here.

[0061] In a more specific embodiment, see Figure 1 and Figure 2A nitride light-emitting layer includes at least one periodic nitride quantum well structure, each nitride quantum well structure includes a nitride quantum well layer, a first nitride quantum barrier layer, a second nitride quantum barrier layer and a third nitride quantum barrier layer stacked in sequence along a selected direction, and at least one composite insertion layer, the composite insertion layer is stacked along a selected direction between the first nitride quantum barrier layer and the second nitride quantum barrier layer and / or between the second nitride quantum and the third nitride quantum barrier layer, wherein the composite insertion layer includes at least one composite Si / Al insertion layer structure.

[0062] Figure 1 The nitride light-emitting layer shown in FIG includes a structural schematic diagram of a single-period nitride quantum well structure. When the nitride light-emitting layer includes multiple-period nitride quantum well structures, the multiple nitride quantum well structures are stacked in sequence along a selected direction. Figure 1 The composite insertion layer shown in the figure is arranged between the first nitride quantum barrier layer and the second nitride quantum barrier layer. Of course, the composite insertion layer can also be arranged between the second nitride quantum and the third nitride quantum barrier layer. Alternatively, the nitride quantum well structure can also include two composite insertion layers, which are respectively arranged between the first nitride quantum barrier layer and the second nitride quantum barrier layer and between the second nitride quantum and the third nitride quantum barrier layer. Figure 2 The composite insertion layer shown is a single composite Si / Al insertion layer structure. Of course, the composite insertion layer can also be a plurality of composite Si / Al insertion layer structures, and the plurality of composite Si / Al insertion layer structures are stacked along a selected direction.

[0063] For details, please refer to Figure 2 and Figure 3 The composite Si / Al insertion layer structure includes a SiN film layer, an AlN filling layer and an AlN film layer, wherein the AlN filling layer is spaced apart in the SiN film layer, and the AlN film layer is stacked on the SiN film layer and the AlN filling layer; and a plurality of AlN microstructures are also provided in the SiN film layer, and a plurality of SiN microstructures are also provided in the AlN film layer.

[0064] Specifically, the SiN membrane layer has multiple nanopore structures, and the AlN filling layer is disposed within the nanopore structures. More specifically, the nanopore structures within the SiN membrane layer are continuous along its thickness, and the AlN filling layer and the SiN membrane layer have the same thickness, and both have a flat surface.

[0065] It should be noted that as the emission wavelength of the nitride light-emitting layer extends toward the long-wave direction, the lattice constant difference between the nitride quantum well layer and the nitride quantum barrier inside the nitride light-emitting layer is large, resulting in the internal stress of the nitride light-emitting layer being aggravated as the emission wavelength of the nitride light-emitting layer extends toward the long-wave direction. The AlN filling layer is subjected to tensile stress in the nitride light-emitting layer, which can compensate for the compressive stress of the nitride quantum well layer and reduce the stress distribution inside the nitride quantum well layer.

[0066] Specifically, on the one hand, the AlIn filling layer containing Al can effectively release the stress inside the AlIn filling layer through relaxation between the internal AlIn and SiN polycrystalline interface, thereby improving the crystal quality of the AlIn filling layer, reducing the absorption of light by defects, and greatly improving the brightness and leakage performance of the epitaxial wafer; on the other hand, the composite structure formed by the AlIn filling layer and the SiN film layer increases the longitudinal extension distance of Si atoms with small atomic radius in the thickness direction. The introduction of Si atoms can be used to modulate the lattice constant of the Al-containing nitride quantum barrier layer, further introducing tensile stress in the nitride quantum barrier layer, and better compensating for the compressive stress of the nitride quantum well layer, reducing the stress distribution inside the nitride quantum well layer, improving the crystal quality and composition uniformity of the nitride quantum well layer, and reducing non-radiative recombination.

[0067] Specifically, the AlN microstructure is integrated with the AlN film layer, and the SiN microstructure is integrated with the SiN film layer. More specifically, the thicknesses of the SiN film layer, the AlN filling layer, and the AlN film layer are all nanometer-scale.

[0068] See also Figure 4 , a method for preparing a nitride light-emitting layer, comprising the following steps:

[0069] (1) Growing a nitride quantum well layer with a thickness of 1 nm to 8 nm at a temperature of 700° C. to 1000° C. and a pressure of 100 torr to 500 torr. Specifically, the nitride quantum well layer may be a group III nitride quantum well layer, and illustratively, the nitride quantum well layer may be an InGaN quantum well layer, etc.

[0070] (2) Under the conditions of a temperature of 750°C to 1050°C and a pressure of 100 torr to 500 torr, a first nitride barrier layer (i.e., the aforementioned first barrier layer, the same below) with a thickness of 1 nm to 3 nm is grown on the nitride quantum well layer.

[0071] Specifically, the first nitride barrier layer is a group III nitride barrier layer. Exemplarily, the first nitride barrier layer can be a GaN layer, an AlGaN layer, an InGaN layer, etc.

[0072] It should be noted that the first nitride barrier layer grown on the nitride quantum well layer can serve as a contact layer of the nitride quantum well layer and also as a growth template for the subsequent composite insertion layer.

[0073] (3) Please also refer to Figure 5 , growing a composite insertion layer on the first nitride barrier layer, specifically comprising:

[0074] S31: epitaxially growing a Si-rich SiN film layer with a thickness of 2 nm to 8 nm on the first nitride barrier layer at a temperature of 1000° C. to 1200° C. and a pressure of 200 torr to 600 torr. It should be noted that the Si-rich SiN film layer is grown using an epitaxial growth process, and the SiN film layer has a micro-nanometer thickness, and the film itself has a discontinuous nanoporous layered film structure, that is, the SiN film layer has multiple nanopore structures;

[0075] S32: Under the conditions of a temperature of 1000°C to 1200°C and a pressure of 100 torr to 300 torr, an AlN filling layer with a thickness of 2nm to 8nm is grown in the nanopore structure in the SiN film layer. The AlN filling layer is filled in the nanopore structure of the SiN film layer, and the thickness of the AlN filling layer is the same as that of the SiN film layer, and the two form a flat surface as a whole.

[0076] Specifically, because the multiple nanopore structures within the SiN membrane are discontinuous, the AlN filling layer is also discontinuous. The AlN filling layer fills the multiple nanopore structures within the SiN membrane, thus forming a membrane structure in which the AlN is surrounded by SiN. The nanopore structures within the SiN membrane are continuous throughout its thickness.

[0077] It should be noted that as the emission wavelength of the nitride light-emitting layer extends toward the long-wave direction, the lattice constant difference between the nitride quantum well layer and the nitride quantum barrier inside the nitride light-emitting layer is large, resulting in the internal stress of the nitride light-emitting layer being aggravated as the emission wavelength of the nitride light-emitting layer extends toward the long-wave direction. The AlN filling layer is subjected to tensile stress in the nitride light-emitting layer, which can compensate for the compressive stress of the nitride quantum well layer and reduce the stress distribution inside the nitride quantum well layer.

[0078] Specifically, on the one hand, the AlIn filling layer containing Al can effectively release the stress inside the AlIn filling layer through relaxation between the internal AlIn and SiN polycrystalline interface, thereby improving the crystal quality of the AlIn filling layer, reducing the absorption of light by defects, and greatly improving the brightness and leakage performance of the epitaxial wafer; on the other hand, the composite structure formed by the AlIn filling layer and the SiN film layer increases the longitudinal extension distance of Si atoms with small atomic radius in the thickness direction. The introduction of Si atoms can be used to modulate the lattice constant of the Al-containing nitride quantum barrier layer, further introducing tensile stress in the nitride quantum barrier layer, and better compensating for the compressive stress of the nitride quantum well layer, reducing the stress distribution inside the nitride quantum well layer, improving the crystal quality and composition uniformity of the nitride quantum well layer, and reducing non-radiative recombination.

[0079] Specifically, due to the low mobility of Al atoms, Al atoms have poor activity when adsorbed on the growth surface, resulting in difficulty in obtaining a smooth surface for the growth of aluminum-containing nitride materials. In particular, as the growth surface increases, the distribution uniformity of Al atoms on the surface becomes worse, seriously affecting the crystal quality of the aluminum-containing nitride material. In step S32, the AlN filling layer is arranged inside the nanopore structure of the SiN film layer, which reduces the problem of poor Al distribution uniformity caused by the in-plane mobility difference of Al atoms. At the same time, since the Si-N bond energy is larger than that of AlN, AlN growth will not nucleate on the surrounding structure formed by the SiN film layer, and a flat surface with the same thickness as the SiN film layer can be obtained. This flat surface provides the basis for the subsequent growth of the Al-containing nitride barrier layer. An Al-containing nitride barrier layer with uniform composition and flat surface can be formed on this flat surface, thereby improving the crystal quality of the Al-containing nitride barrier layer, reducing non-radiative recombination in the nitride light-emitting layer, and improving the luminous brightness and efficiency of the nitride light-emitting layer.

[0080] S33: Under the conditions of a temperature of 950°C to 1000°C and a pressure of 50 torr to 200 torr, Al heat treatment is performed on the entire surface of the SiN film layer and the AlN filling layer to generate an Al metal covering layer (i.e., the aforementioned Al layer, the same below) with a thickness of 2nm to 5nm on the surface thereof. The Al metal covering layer continuously covers the surfaces of the AlN filling layer and the SiN film layer, thereby forming a composite insertion layer precursor.

[0081] S34: performing nitrogen heat treatment on the composite insertion layer precursor for 5s to 20s at a temperature of 1000° C. to 1200° C. and a pressure of 200 torr to 400 torr, thereby transforming the composite insertion layer precursor into a composite insertion layer.

[0082] Specifically, during the nitrogen heat treatment process, the Al metal covering layer is nitrided to form an AlN film layer, and the AlN film layer is combined with the AlN filling layer into one. On the other hand, the excess Si atoms in the SiN film layer and at least part of the Al atoms in the Al metal covering layer form mutual diffusion, Si atoms diffuse into the Al metal covering layer, and at the same time, Al atoms diffuse into the Si-rich SiN film layer. During the nitrogen heat treatment process, Al atoms diffuse downward to form an AlN microstructure, and Si atoms diffuse upward to form a SiN microstructure, and finally form a composite insertion layer with a mixed distribution of AlN microstructure and SiN microstructure, wherein the AlN film layer formed by nitridation serves as the AlN film layer, and the SiN film layer forms the SiN film layer. This not only reduces the absorption problem caused by the Si-rich atoms in the SiN insertion layer in the carrier transport process in the nitride light-emitting layer, but also improves the uniformity of carrier injection, thereby improving the luminous brightness and efficiency of the nitride light-emitting layer.

[0083] (4) Under the conditions of a temperature of 1000°C to 1200°C and a pressure of 50 torr to 300 torr, a second nitride barrier layer (i.e., the aforementioned second barrier layer, the same below) with a thickness of 6 nm to 12 nm is grown on the composite insertion layer.

[0084] Specifically, the second nitride barrier layer is an Al-doped nitride layer, the Al component content of the second nitride barrier layer is 0.1-0.5, and the doping concentration is 2×10 17 cm -3 ~8×10 17 cm -3 .

[0085] It should be noted that the functions of the aluminum-doped nitride barrier layer include: due to the difference in lattice constants, the aluminum-doped nitride barrier layer is subjected to tensile stress in the nitride light-emitting layer, which can compensate for the compressive stress of the nitride quantum well layer, reduce the stress distribution inside the nitride quantum well layer, improve the crystal quality and composition uniformity of the nitride quantum well layer, and reduce non-radiative recombination. At the same time, the aluminum-doped nitride quantum barrier layer has a high potential barrier, which can improve the limiting effect of electron injection into the light-emitting layer and reduce electron leakage. Furthermore, the aluminum-doped nitride barrier layer can use doping to reduce the polarization electric field in the nitride light-emitting layer, increase the overlap of electron and hole wave functions in the nitride light-emitting layer, and improve the luminous brightness and efficiency of the nitride light-emitting layer.

[0086] Specifically, as the emission wavelength of the nitride light-emitting layer extends toward the long-wave direction, the lattice constant difference between the nitride quantum well layer and the nitride quantum barrier inside the nitride light-emitting layer is large, resulting in the internal stress of the nitride light-emitting layer being aggravated as the emission wavelength of the nitride light-emitting layer extends toward the long-wave direction. Because the aluminum-doped nitride barrier layer is subjected to tensile stress in the nitride light-emitting layer, it can compensate for the compressive stress of the nitride quantum well layer and reduce the stress distribution inside the nitride quantum well layer. Therefore, the aluminum-doped nitride barrier layer can improve the crystal quality and composition uniformity of the nitride quantum well layer and reduce non-radiative recombination. At the same time, the aluminum-doped nitride barrier layer has a high potential barrier, which can improve the limiting effect of electron injection into the light-emitting layer, reduce electron leakage, and improve the luminous brightness and efficiency of the nitride light-emitting layer.

[0087] (5) Growing a third nitride barrier layer with a thickness of 1 nm to 3 nm on the second nitride barrier layer at a temperature of 1000° C. to 1200° C. and a pressure of 100 torr to 500 torr.

[0088] Specifically, the third nitride barrier layer is a Group III nitride barrier layer. Exemplarily, the third nitride barrier layer can be a GaN layer, an AlGaN layer, an InGaN layer, etc.

[0089] Specifically, the third nitride barrier layer is mainly used to provide a growth template for the nitride quantum well layer during the periodic overlapping growth process, thereby improving the interface quality of the nitride quantum well layer, thereby improving the uniformity of the internal composition and thickness of the nitride quantum well layer, and improving the luminous brightness and efficiency of the nitride light-emitting layer.

[0090] (6) Periodically repeating steps (1) to (5) for more than 0 times to form a nitride quantum well structure. For example, steps (1) to (5) may be periodically repeated for a total of 1 to 8 cycles.

[0091] (7) Under the conditions of temperature of 700℃~1000℃ and pressure of 100torr~500torr, a post-nitride quantum well layer with a thickness of 2nm~10nm is grown on the nitride quantum barrier layer.

[0092] Specifically, the post-nitride quantum well layer is a Group III nitride quantum well layer. Exemplarily, the post-nitride quantum well layer may be an InGaN layer or the like.

[0093] (8) Under the conditions of a temperature of 950°C to 1050°C and a pressure of 100 torr to 500 torr, a post-nitride quantum barrier layer with a thickness of 3 nm to 10 nm is grown on the post-nitride quantum well layer.

[0094] Specifically, the post-nitride quantum barrier layer is a group III nitride well layer. Exemplarily, the post-nitride quantum well layer can be a GaN layer, an AlGaN layer, an InGaN layer, etc.

[0095] It should be noted that steps (7) and (8) are preferred processes. The relatively thick post-nitride quantum well layer in step (7) can improve the carrier injection capability of the quantum well layer serving as the main light-emitting layer, and the relatively thin post-nitride quantum barrier layer in step (8) can improve the hole transmission capability to the nitride light-emitting layer, thereby improving the hole distribution in the nitride quantum well layer within the periodic overlapping period, and thus improving the luminous brightness and efficiency of the nitride light-emitting layer.

[0096] Specifically, on the one hand, the present invention utilizes the Al metal covering layer and the diffusion of Si-rich atoms to increase the longitudinal extension distance of Si atoms with small atomic radius in the thickness direction, and can utilize the introduction of Si atoms to modulate the lattice constant of the aluminum-doped nitride barrier layer, further introducing tensile stress in the aluminum-doped nitride barrier layer, which can better compensate for the compressive stress of the nitride quantum well layer, reduce the stress distribution inside the nitride quantum well layer, improve the crystal quality and composition uniformity of the nitride quantum well layer, and reduce non-radiative recombination. On the other hand, the AlIn filling layer containing Al can effectively release the stress inside the AlIn filling layer through relaxation between the internal AlIn and SiN polycrystalline interface, thereby improving the crystal quality of the AlIn filling layer, reducing the absorption of light by defects, and greatly improving the brightness and leakage performance of the epitaxial wafer.

[0097] More specifically, due to the low mobility of Al atoms, Al atoms have poor activity when adsorbed on the growth surface, which makes it difficult to obtain a flat surface when growing aluminum-containing nitride materials. In particular, when the aluminum-containing nitride material is grown on a graphic structure layer with an uneven surface, the crystal quality of the aluminum-containing nitride material is seriously affected. When used in a nitride quantum barrier layer, high dislocation centers will be formed in the nitride light-emitting layer, reducing the non-radiative recombination efficiency. Moreover, due to the low mobility of Al atoms, Al atoms have poor activity when adsorbed on the growth surface, resulting in difficulty in obtaining a smooth surface when growing aluminum-containing nitride materials. In particular, as the growth surface increases, the distribution uniformity of Al atoms on the surface becomes worse, seriously affecting the crystal quality of the aluminum-containing nitride material. In step S32 of the present invention, the AlN filling layer is arranged inside the SiN nanopore structure, which reduces the problem of poor Al distribution uniformity caused by the in-plane mobility difference of Al atoms. At the same time, since the Si-N bond energy is larger than that of AlN, AlN growth will no longer nucleate on the surrounding structure formed by the SiN film layer, and a flat surface with the same thickness as the SiN film layer can be obtained. This flat surface provides the basis for the subsequent growth of an aluminum-doped nitride barrier layer. An aluminum-doped nitride barrier layer with uniform composition and a flat surface can be formed on this flat surface, thereby improving the crystal quality of the aluminum-doped nitride barrier layer, reducing non-radiative recombination in the nitride light-emitting layer, and improving the luminous brightness and efficiency of the nitride light-emitting layer.

[0098] It should be noted that, in another embodiment of the present invention, steps S31-S34 of growing a composite insertion layer can be performed after growing the second barrier layer and before growing the third barrier layer. Of course, in another embodiment of the present invention, steps S31-S34 of growing a composite insertion layer can be performed after growing the first barrier layer and before growing the second barrier layer, as well as after growing the second barrier layer and before growing the third barrier layer.

[0099] Example 1

[0100] A method for preparing a nitride light-emitting layer comprises the following steps:

[0101] (1) Grow an InGaN quantum well layer with a thickness of 4 nm at a temperature of 800°C and a pressure of 150 torr.

[0102] (2) Under the conditions of temperature of 750℃ and pressure of 100torr, an AlGaN barrier layer with a thickness of 1nm is grown on the InGaN quantum well layer. The Al component content of the AlGaN barrier layer is 0.1 and the doping concentration is 2×10 17 cm -3 .

[0103] (3) Growing a Si / Al composite insertion layer on the AlGaN barrier layer, specifically including:

[0104] S31: epitaxially growing a 2 nm thick SiN film rich in Si atoms on the AlGaN barrier layer at a temperature of 1000° C. and a pressure of 200 torr, wherein the SiN film has a plurality of nanopore structures formed due to its own discontinuity.

[0105] S32: Under the conditions of a temperature of 1000°C and a pressure of 100 torr, an AlN filling layer with a thickness of 2 nm is grown in the nanopore structure in the SiN film layer. The AlN filling layer is filled in the nanopore structure of the SiN film layer, and the thickness of the AlN filling layer is the same as that of the SiN film layer, and the two form a flat surface as a whole.

[0106] S33: Under the conditions of a temperature of 980°C and a pressure of 100 torr, Al heat treatment is performed on the entire surface of the SiN film layer and the AlN filling layer to generate an Al metal covering layer with a thickness of 3 nm on the surface thereof. The Al metal covering layer continuously covers the surfaces of the AlN filling layer and the SiN film layer, thereby forming a composite insertion layer precursor.

[0107] S34: performing nitrogen heat treatment on the composite insertion layer precursor for 5 seconds at a temperature of 1100° C. and a pressure of 300 torr, thereby transforming the composite insertion layer precursor into a composite insertion layer.

[0108] (4) Under the conditions of temperature of 1050℃ and pressure of 200torr, a 10nm thick AlGaN barrier layer was grown on the composite insertion layer. The Al component content of the AlGaN barrier layer was 0.2 and the doping concentration was 3×10 17 cm -3 .

[0109] (5) Under the conditions of temperature of 1050℃ and pressure of 200torr, an AlGaN barrier layer with a thickness of 2nm is grown on the AlGaN barrier layer. The Al component content of the AlGaN barrier layer is 0.3 and the doping concentration is 6×10 17 cm -3 , thus forming a nitride quantum well structure.

[0110] Example 2

[0111] A method for preparing a nitride light-emitting layer comprises the following steps:

[0112] (1) Grow an InGaN quantum well layer with a thickness of 3 nm at a temperature of 700°C and a pressure of 100 torr.

[0113] (2) Under the conditions of temperature of 950℃ and pressure of 300torr, a 2nm thick AlGaN barrier layer was grown on the InGaN quantum well layer. The Al component content of the AlGaN barrier layer was 0.1 and the doping concentration was 2×1017 cm -3 .

[0114] (3) Growing a Si / Al composite insertion layer on the AlGaN barrier layer, specifically including:

[0115] S31: epitaxially growing a SiN film layer rich in Si atoms with a thickness of 5 nm on the AlGaN barrier layer at a temperature of 1050° C. and a pressure of 300 torr, wherein the SiN film layer has a plurality of nanopore structures formed due to its own discontinuity.

[0116] S32: Under the conditions of a temperature of 1050°C and a pressure of 150 torr, an AlN filling layer with a thickness of 5 nm is grown in the nanopore structure in the SiN membrane layer. The AlN filling layer is filled in the nanopore structure of the SiN membrane layer, and the thickness of the AlN filling layer is the same as that of the SiN membrane layer, and the two form a flat surface as a whole.

[0117] S33: Under the conditions of a temperature of 950°C and a pressure of 50 torr, Al heat treatment is performed on the entire surface of the SiN film layer and the AlN filling layer to generate an Al metal covering layer with a thickness of 2 nm on the surface thereof. The Al metal covering layer continuously covers the surfaces of the AlN filling layer and the SiN film layer, thereby forming a composite insertion layer precursor.

[0118] S34: performing nitrogen heat treatment on the composite insertion layer precursor at a temperature of 1000° C. and a pressure of 200 torr for 8 seconds, thereby transforming the composite insertion layer precursor into a composite insertion layer.

[0119] (4) Under the conditions of temperature of 1000℃ and pressure of 50torr, a 6nm thick AlGaN barrier layer was grown on the composite insertion layer. The Al component content of the AlGaN barrier layer was 0.1 and the doping concentration was 2×10 17 cm -3 .

[0120] (5) Under the conditions of temperature of 1000℃ and pressure of 100torr, an AlGaN barrier layer with a thickness of 1nm is grown on the AlGaN barrier layer. The Al component content of the AlGaN barrier layer is 0.2 and the doping concentration is 6×10 17 cm -3 , thus forming a nitride quantum well structure.

[0121] Example 3

[0122] A method for preparing a nitride light-emitting layer comprises the following steps:

[0123] (1) Grow an 8nm thick InGaN quantum well layer at a temperature of 1000°C and a pressure of 500 torr.

[0124] (2) Under the conditions of temperature of 1050℃ and pressure of 500torr, a 3nm thick AlGaN barrier layer was grown on the InGaN quantum well layer. The Al component content of the AlGaN barrier layer was 0.2 and the doping concentration was 2×10 17 cm -3 .

[0125] (3) Growing a Si / Al composite insertion layer on the AlGaN barrier layer, specifically including:

[0126] S31: epitaxially growing an 8 nm thick SiN film rich in Si atoms on the AlGaN barrier layer at a temperature of 1200° C. and a pressure of 600 torr, wherein the SiN film has a plurality of nanopore structures formed due to its own discontinuity.

[0127] S32: Under the conditions of a temperature of 1200°C and a pressure of 300 torr, an AlN filling layer with a thickness of 8 nm is grown in the nanopore structure in the SiN film layer. The AlN filling layer is filled in the nanopore structure of the SiN film layer, and the thickness of the AlN filling layer is the same as that of the SiN film layer, and the two form a flat surface as a whole.

[0128] S33: Under the conditions of a temperature of 1000°C and a pressure of 200 torr, Al heat treatment is performed on the entire surface of the SiN film layer and the AlN filling layer to generate an Al metal covering layer with a thickness of 5 nm on the surface thereof. The Al metal covering layer continuously covers the surfaces of the AlN filling layer and the SiN film layer, thereby forming a composite insertion layer precursor.

[0129] S34: performing nitrogen heat treatment on the composite insertion layer precursor at a temperature of 1200° C. and a pressure of 300 torr for 20 seconds, thereby transforming the composite insertion layer precursor into a composite insertion layer.

[0130] (4) Under the conditions of temperature of 1200℃ and pressure of 300torr, a 12nm thick AlGaN barrier layer was grown on the composite insertion layer. The Al component content of the AlGaN barrier layer was 0.5 and the doping concentration was 8×10 17 cm -3 .

[0131] (5) Under the conditions of temperature of 1200℃ and pressure of 500torr, an AlGaN barrier layer with a thickness of 3nm is grown on the AlGaN barrier layer. The Al component content of the AlGaN barrier layer is 0.4 and the doping concentration is 6×10 17 cm -3 , thus forming a nitride quantum well structure.

[0132] Example 4

[0133] A method for preparing a nitride light-emitting layer comprises the following steps:

[0134] (1) Grow an InGaN quantum well layer with a thickness of 4 nm at a temperature of 800°C and a pressure of 150 torr.

[0135] (2) Under the conditions of temperature of 750℃ and pressure of 100torr, an AlGaN barrier layer with a thickness of 1nm is grown on the InGaN quantum well layer. The Al component content of the AlGaN barrier layer is 0.1 and the doping concentration is 2×10 17 cm -3 .

[0136] (3) Growing a Si / Al composite insertion layer on the AlGaN barrier layer, specifically including:

[0137] S31: epitaxially growing a 2 nm thick SiN film rich in Si atoms on the AlGaN barrier layer at a temperature of 1000° C. and a pressure of 200 torr, wherein the SiN film has a plurality of nanopore structures formed due to its own discontinuity.

[0138] S32: Under the conditions of a temperature of 1000°C and a pressure of 100 torr, an AlN filling layer with a thickness of 2 nm is grown in the nanopore structure in the SiN film layer. The AlN filling layer is filled in the nanopore structure of the SiN film layer, and the thickness of the AlN filling layer is the same as that of the SiN film layer, and the two form a flat surface as a whole.

[0139] S33: Under the conditions of a temperature of 980°C and a pressure of 100 torr, Al heat treatment is performed on the entire surface of the SiN film layer and the AlN filling layer to generate an Al metal covering layer with a thickness of 3 nm on the surface thereof. The Al metal covering layer continuously covers the surfaces of the AlN filling layer and the SiN film layer, thereby forming a composite insertion layer precursor.

[0140] S34: performing nitrogen heat treatment on the composite insertion layer precursor for 5 seconds at a temperature of 1100° C. and a pressure of 300 torr, thereby transforming the composite insertion layer precursor into a composite insertion layer.

[0141] (4) Under the conditions of temperature of 1050℃ and pressure of 200torr, a 10nm thick AlGaN barrier layer was grown on the composite insertion layer. The Al component content of the AlGaN barrier layer was 0.2 and the doping concentration was 3×10 17 cm -3 .

[0142] (5) Under the conditions of temperature of 1050℃ and pressure of 200torr, an AlGaN barrier layer with a thickness of 2nm is grown on the AlGaN barrier layer. The Al component content of the AlGaN barrier layer is 0.3 and the doping concentration is 6×10 17 cm -3 .

[0143] (6) Repeat steps (1) to (5) 2 times periodically and alternately to form a nitride quantum well structure.

[0144] Example 5

[0145] A method for preparing a nitride light-emitting layer comprises the following steps:

[0146] (1) Grow an InGaN quantum well layer with a thickness of 4 nm at a temperature of 800°C and a pressure of 150 torr.

[0147] (2) Under the conditions of temperature of 750℃ and pressure of 100torr, an AlGaN barrier layer with a thickness of 1nm is grown on the GaN quantum well layer. The Al component content of the AlGaN barrier layer is 0.1 and the doping concentration is 2×10 17 cm -3 .

[0148] (3) Growing a Si / Al composite insertion layer on the AlGaN barrier layer, specifically including:

[0149] S31: epitaxially growing a 2 nm thick SiN film rich in Si atoms on the AlGaN barrier layer at a temperature of 1000° C. and a pressure of 200 torr, wherein the SiN film has a plurality of nanopore structures formed due to its own discontinuity.

[0150] S32: Under the conditions of a temperature of 1000°C and a pressure of 100 torr, an AlN filling layer with a thickness of 2 nm is grown in the nanopore structure in the SiN film layer. The AlN filling layer is filled in the nanopore structure of the SiN film layer, and the thickness of the AlN filling layer is the same as that of the SiN film layer, and the two form a flat surface as a whole.

[0151] S33: Under the conditions of a temperature of 980°C and a pressure of 100 torr, Al heat treatment is performed on the entire surface of the SiN film layer and the AlN filling layer to generate an Al metal covering layer with a thickness of 3 nm on the surface thereof. The Al metal covering layer continuously covers the surfaces of the AlN filling layer and the SiN film layer, thereby forming a composite insertion layer precursor.

[0152] S34: performing nitrogen heat treatment on the composite insertion layer precursor for 5 seconds at a temperature of 1100° C. and a pressure of 300 torr, thereby transforming the composite insertion layer precursor into a composite insertion layer.

[0153] (4) Under the conditions of temperature of 1050℃ and pressure of 200torr, a 10nm thick AlGaN barrier layer was grown on the composite insertion layer. The Al component content of the AlGaN barrier layer was 0.2 and the doping concentration was 3×10 17 cm -3 .

[0154] (5) Under the conditions of temperature of 1050℃ and pressure of 200torr, an AlGaN barrier layer with a thickness of 2nm is grown on the AlGaN barrier layer. The Al component content of the AlGaN barrier layer is 0.3 and the doping concentration is 6×10 17 cm -3 , thus forming a nitride quantum well structure.

[0155] (6) A post-InGaN quantum well layer with a thickness of 2 nm was grown on the nitride quantum well structure at a temperature of 700°C and a pressure of 100 torr.

[0156] (7) A post-GaN quantum barrier layer with a thickness of 3 nm is grown on the post-InGaN quantum well layer at a temperature of 950°C and a pressure of 100 torr.

[0157] Comparative Example 1

[0158] A method for preparing a nitride light-emitting layer comprises the following steps:

[0159] (1) Grow an InGaN quantum well layer with a thickness of 4 nm at a temperature of 800°C and a pressure of 150 torr.

[0160] (2) Under the conditions of temperature of 750℃ and pressure of 100torr, an AlGaN barrier layer with a thickness of 1nm is grown on the InGaN quantum well layer. The Al component content of the AlGaN barrier layer is 0.1 and the doping concentration is 2×10 17 cm -3 .

[0161] (3) Growing a Si / Al composite insertion layer on the AlGaN barrier layer, specifically including:

[0162] S31: epitaxially growing a SiN film layer with a thickness of 2 nm on the AlGaN barrier layer at a temperature of 1000° C. and a pressure of 200 torr, wherein the SiN film layer has a plurality of nanopore structures formed due to its own discontinuity.

[0163] S32: Under the conditions of a temperature of 1000°C and a pressure of 100 torr, an AlN filling layer with a thickness of 2 nm is grown in the nanopore structure in the SiN film layer, the AlN filling layer is filled in the nanopore structure of the SiN film layer, and the AlN filling layer and the SiN film layer form a flat surface as a whole.

[0164] S33: Under the conditions of a temperature of 1000°C and a pressure of 100 torr, an AlN film layer with a thickness of 3 nm is formed on the entire surface of the SiN film layer and the AlN filling layer. The AlN film layer continuously covers the surface of the AlN filling layer and the SiN film layer, thereby forming a composite insertion layer, such as Figure 6 shown.

[0165] (4) Under the conditions of temperature of 1050℃ and pressure of 200torr, a 10nm thick AlGaN barrier layer was grown on the composite insertion layer. The Al component content of the AlGaN barrier layer was 0.2 and the doping concentration was 3×10 17 cm -3 .

[0166] (5) Under the conditions of temperature of 1050℃ and pressure of 200torr, an AlGaN barrier layer with a thickness of 2nm is grown on the AlGaN barrier layer. The Al component content of the AlGaN barrier layer is 0.3 and the doping concentration is 6×10 17 cm -3 .

[0167] Comparative Example 2

[0168] A method for preparing a nitride light-emitting layer comprises the following steps:

[0169] (1) Grow an InGaN quantum well layer with a thickness of 4 nm at a temperature of 800°C and a pressure of 150 torr.

[0170] (2) Under the conditions of temperature of 750℃ and pressure of 100torr, an AlGaN barrier layer with a thickness of 1nm is grown on the InGaN quantum well layer. The Al component content of the AlGaN barrier layer is 0.1 and the doping concentration is 2×10 17 cm -3 .

[0171] (3) Growing a Si / Al composite insertion layer on the AlGaN barrier layer, specifically including:

[0172] S31: growing an AlN filling layer with a thickness of 2 nm on the AlGaN barrier layer under the conditions of a temperature of 1000° C. and a pressure of 100 Torr.

[0173] S32: Under the conditions of a temperature of 980°C and a pressure of 100 torr, Al heat treatment is performed on the entire surface of the SiN film layer and the AlN filling layer to generate an Al metal covering layer with a thickness of 3 nm on the surface thereof. The Al metal covering layer continuously covers the surfaces of the AlN filling layer and the SiN film layer, thereby forming a composite insertion layer precursor.

[0174] S33: performing nitrogen heat treatment on the composite insertion layer precursor for 5 seconds at a temperature of 1100° C. and a pressure of 300 torr, thereby transforming the composite insertion layer precursor into a composite insertion layer.

[0175] (4) Under the conditions of temperature of 1050℃ and pressure of 200torr, a 10nm thick AlGaN barrier layer was grown on the composite insertion layer. The Al component content of the AlGaN barrier layer was 0.2 and the doping concentration was 3×10 17 cm -3 .

[0176] (5) Under the conditions of temperature of 1050℃ and pressure of 200torr, an AlGaN barrier layer with a thickness of 2nm is grown on the AlGaN barrier layer. The Al component content of the AlGaN barrier layer is 0.3 and the doping concentration is 6×10 17 cm -3 .

[0177] Comparative Example 3

[0178] A method for preparing a nitride light-emitting layer comprises the following steps:

[0179] (1) Grow an InGaN quantum well layer with a thickness of 4 nm at a temperature of 800°C and a pressure of 150 torr.

[0180] (2) Under the conditions of temperature of 750℃ and pressure of 100torr, an AlGaN barrier layer with a thickness of 1nm is grown on the InGaN quantum well layer. The Al component content of the AlGaN barrier layer is 0.1 and the doping concentration is 2×10 17 cm -3 .

[0181] (3) Growing a Si / Al composite insertion layer on the AlGaN barrier layer, specifically including:

[0182] S31: epitaxially growing a 2 nm thick SiN film rich in Si atoms on the AlGaN barrier layer at a temperature of 1000° C. and a pressure of 200 torr, wherein the SiN film has a plurality of nanopore structures formed due to its own discontinuity.

[0183] S32: Under the conditions of a temperature of 1000°C and a pressure of 100 torr, an AlN filling layer with a thickness of 2 nm is grown in the nanopore structure in the SiN membrane layer. The AlN filling layer is filled in the nanopore structure of the SiN membrane layer, and the AlN filling layer and the SiN membrane layer form a flat surface as a whole, thereby forming a composite insertion layer.

[0184] (4) Under the conditions of temperature of 1050℃ and pressure of 200torr, a 10nm thick AlGaN barrier layer was grown on the composite insertion layer. The Al component content of the AlGaN barrier layer was 0.2 and the doping concentration was 3×10 17 cm -3 .

[0185] (5) Under the conditions of temperature of 1050℃ and pressure of 200torr, an AlGaN barrier layer with a thickness of 2nm is grown on the AlGaN barrier layer. The Al component content of the AlGaN barrier layer is 0.3 and the doping concentration is 6×10 17 cm -3 .

[0186] Ten epitaxial wafers were prepared using 8-inch sapphire substrates according to Examples 1-5 and Comparative Examples 1-3, and the wavelength std of the epitaxial wafers was tested using a photoluminescence spectrometer. The (102) half-peak width was tested using an X-ray diffractometer (XRD), and the statistical epitaxial yield of the epitaxial wafers was calculated (the number of substrate wafers minus the number of substrate cracks and epitaxial wafer surface cracks / the number of substrate wafers). Then, the same chip processing technology was used to process the nitride light-emitting layers obtained in Examples 1-5 and Comparative Examples 1-3 to obtain Micro-LED chips with a size of 3 mil*5 mil. The obtained Micro-LED chips were tested, and the results are shown in Table 1.

[0187] It should be noted that the current mainstream size of nitride light-emitting layers in the industry has shifted from the early 2-inch to 4-inch. A few leading companies have already achieved mass production of 6-inch mass production processes, while 8-inch is still in the development stage. The present invention uses the preparation of nitride light-emitting layers on large-size 8-inch sapphire substrates as an example to illustrate.

[0188] Table 1 Performance test results of Micro-LED chips obtained based on Examples 1-5 and Comparative Examples 1-3

[0189] Epitaxial yield （102） std / nm Brightness / mW Quantum efficiency / % Leakage yield / % Example 1 100 195 0.45 12.9 31.2 100 Example 2 100 193 0.52 12.1 33.4 99 Example 3 100 190 0.44 13.1 30.5 99 Example 4 100 191 0.61 12.8 31.8 100 Example 5 100 197 0.47 13.5 37.1 98 Comparative Example 1 80 238 1.45 11.2 26 96 Comparative Example 2 0 315 1.82 \ \ \ Comparative Example 3 20 256 1.57 9.6 15 89

[0190] It can be seen from Table 1 that the Micro-LED chips obtained based on Examples 1-5 have high epitaxial yield, low (102) crystal plane half-width, lower wavelength std, high brightness and quantum efficiency, and excellent leakage performance. On the one hand, the relaxation between the internal AIN and SiN polycrystalline interface can effectively release the stress inside the AIN filling layer, improve the crystal quality of the AIN filling layer, reduce the absorption of light by defects, and greatly improve the brightness and leakage performance of the epitaxial wafer; on the other hand, the composite structure formed by the AIN filling layer and the SiN film layer modulates the lattice constant of the Al-containing nitride quantum barrier layer in the thickness direction, reduces the stress distribution inside the nitride quantum well layer, improves the crystal quality and composition uniformity of the nitride quantum well layer, and reduces non-radiative recombination.

[0191] The present invention overcomes the problem of poor growth uniformity of large-size Micro-LED epitaxial quantum wells, is suitable for large-size long-wave emission, and greatly improves the brightness and luminous efficiency of Micro-LED epitaxial wafers.

[0192] It should be understood that the above embodiments are merely illustrative of the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent variations or modifications made in accordance with the spirit and substance of the present invention are intended to be encompassed within the scope of protection of the present invention.

Claims

1. A composite Si / Al insertion layer structure, arranged between two adjacent barrier layers of a quantum well structure, characterized in that: The composite Si / Al insertion layer structure comprises: a SiN film layer, an AlN filling layer and an AlN film layer, wherein the AlN filling layer is spaced apart in the SiN film layer, and the AlN film layer is stacked on the SiN film layer and the AlN filling layer; Furthermore, a plurality of AlN microstructures are provided in the SiN film layer, and a plurality of SiN microstructures are provided in the AlN film layer.

2. The composite Si / Al insertion layer structure according to claim 1, characterized in that: The SiN film layer has a plurality of nanopore structures therein, and the AlN filling layer is arranged in the nanopore structures.

3. The composite Si / Al insertion layer structure according to claim 2, characterized in that: The nanopore structure is a through-hole structure that penetrates along the thickness direction of the SiN film layer, and the surface of the AlN filling layer is flush with the surface of the SiN film layer.

4. The composite Si / Al insertion layer structure according to claim 1, characterized in that: The AlN microstructure is integrated with the AlN film layer.

5. The composite Si / Al insertion layer structure according to claim 1, characterized in that: The SiN microstructure and the SiN film layer are integrated.

6. The composite Si / Al insertion layer structure according to claim 1, characterized in that: The thicknesses of the SiN film layer, the AlN filling layer and the AlN film layer are all in the nanometer scale.

7. The composite Si / Al insertion layer structure according to claim 1 or 6, characterized in that: The SiN film layer and the AlN filling layer have the same thickness.

8. A method for preparing a composite Si / Al insertion layer structure, wherein the composite Si / Al insertion layer structure is disposed between two adjacent barrier layers of a quantum well structure, characterized in that: The preparation method of the composite Si / Al insertion layer structure comprises: Providing a Si atom-rich SiN film layer, wherein a selected surface of the SiN film layer has a plurality of nanopore structures; Growing AlN in the nanopore structure to form an AlN filling layer; forming an Al layer on a selected surface of the SiN film layer, wherein the Al layer also covers the AlN filling layer, thereby forming a composite Si / Al insertion layer structure precursor; The composite Si / Al insertion layer structure precursor is heat-treated in an environment in the presence of a nitrogen source, so that part of the Al atoms in the Al layer and the surplus Si atoms in the SiN film layer are mutually dissolved and diffused, and the Al atoms and Si atoms in the composite Si / Al insertion layer structure precursor are respectively combined with the N atoms provided by the nitrogen source to form AlN and SiN, wherein a part of the AlN formed by the heat treatment is stacked on the upper surface of the SiN film layer to form an AlN film layer, and another part of the AlN is distributed inside the SiN film layer to form a plurality of AlN microstructures. At least a part of the SiN formed by the heat treatment is distributed inside the AlN film layer to form a plurality of SiN microstructures, thereby forming a composite Si / Al insertion layer structure.

9. The method for preparing the composite Si / Al insertion layer structure according to claim 8, characterized in that: The surface of the AlN filling layer is flush with the selected surface of the SiN film layer.

10. The method for preparing the composite Si / Al insertion layer structure according to claim 9, characterized in that: The thickness of the AlN filling layer is the same as the thickness of the SiN film layer.

11. The method for preparing the composite Si / Al insertion layer structure according to claim 8, characterized in that: The nanopore structure is a through hole that penetrates along the thickness direction of the SiN film layer.

12. The method for preparing the composite Si / Al insertion layer structure according to claim 8, characterized in that: The nanopore structure is formed by the discontinuity of the SiN film layer's own film structure.

13. The method for preparing the composite Si / Al insertion layer structure according to claim 8, characterized in that: Specifically include: Growing a SiN film rich in Si atoms under a first temperature and a first pressure, wherein a selected surface of the SiN film has a plurality of nanopore structures penetrating along the thickness direction of the SiN film; Under second temperature and second pressure conditions, growing AlN in the nanopore structure of the SiN membrane layer, filling the nanopore structure with AlN, and forming an AlN filling layer, wherein the surface of the AlN filling layer is flush with the selected surface of the SiN membrane layer; forming an Al layer on a selected surface of the SiN film layer under a third temperature and a third pressure condition, wherein the Al layer also covers the AlN filling layer, thereby forming a composite Si / Al insertion layer structure precursor; Under fourth temperature and fourth pressure conditions, the composite Si / Al insertion layer structure precursor is heat-treated in an environment with a nitrogen source, so that part of the Al atoms in the Al layer and the surplus Si atoms in the SiN film layer are mutually dissolved and diffused, and the Al atoms and Si atoms in the composite Si / Al insertion layer structure precursor are respectively combined with the N atoms provided by the nitrogen source to form AlN and SiN, wherein a part of the AlN formed by the heat treatment is stacked on the upper surface of the SiN film layer to form an AlN film layer, and another part of the AlN is distributed inside the SiN film layer to form a plurality of AlN microstructures. At least a part of the SiN formed by the heat treatment is distributed inside the AlN film layer to form a plurality of SiN microstructures, thereby forming a composite Si / Al insertion layer structure.

14. The method for preparing the composite Si / Al insertion layer structure according to claim 13, characterized in that: The first temperature is 1000° C. to 1200° C., and the first pressure is 200 torr to 600 torr.

15. The method for preparing the composite Si / Al insertion layer structure according to claim 13, characterized in that: The second temperature is 1000° C. to 1200° C., and the second pressure is 100 torr to 300 torr.

16. The method for preparing the composite Si / Al insertion layer structure according to claim 13, characterized in that: The third temperature is 950° C. to 1000° C., and the third pressure is 50 torr to 200 torr.

17. The method for preparing the composite Si / Al insertion layer structure according to claim 13, characterized in that: The fourth temperature is 1000° C. to 1200° C., and the fourth pressure is 200 torr to 400 torr.

18. The method for preparing the composite Si / Al insertion layer structure according to claim 13, characterized in that: The heat treatment time is 5s to 20s.

19. The method for preparing the composite Si / Al insertion layer structure according to claim 3, characterized in that: The thickness of the SiN film layer is 2nm~8nm.

20. The method for preparing a composite Si / Al insertion layer structure according to claim 13, characterized in that: The thickness of the AlN filling layer is 2nm-8nm.

21. The method for preparing a composite Si / Al insertion layer structure according to claim 13, characterized in that: The thickness of the Al layer is 2nm~5nm.

22. A quantum well structure comprising at least one quantum well layer and at least one quantum barrier layer stacked in sequence along a selected direction, characterized in that: The quantum barrier layer includes at least two barrier layers stacked along the selected direction and at least one composite insertion layer, wherein at least one composite insertion layer is arranged between two adjacent barrier layers, and the composite insertion layer includes the composite Si / Al insertion layer structure according to any one of claims 1 to 7.

23. The quantum well structure according to claim 22, characterized in that: The composite insertion layer includes a plurality of composite Si / Al insertion layer structures periodically and repeatedly stacked along the selected direction.

24. The quantum well structure according to claim 22, characterized in that: The quantum barrier layer includes a first barrier layer, a second barrier layer, and a third barrier layer stacked along the selected direction, and the composite insertion layer is stacked between the second barrier layer and at least one of the first barrier layer and the third barrier layer.

25. The quantum well structure according to claim 22 or 24, characterized in that: The quantum well layer and the quantum barrier layer are periodically and repeatedly stacked.

26. The quantum well structure according to claim 22, characterized in that: The materials of the quantum well layer and the quantum barrier layer are both nitride.

27. The quantum well structure according to claim 26, characterized in that: The materials of the quantum well layer and the quantum barrier layer are both group III nitride.

28. An epitaxial wafer, characterized in that: include: The quantum well structure according to any one of claims 22 to 27.

29. The epitaxial wafer according to claim 28, characterized in that: The epitaxial wafer includes a Micro-LED epitaxial wafer.

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