A GaN-based light-emitting diode epitaxial wafer and its fabrication method

Abstract

This invention provides a GaN-based light-emitting diode epitaxial wafer and its fabrication method. The GaN-based light-emitting diode epitaxial wafer includes multiple quantum well layers, which are periodic structures of alternating quantum well layers, quantum well cap layers, and quantum barrier layers. The quantum well cap layer includes sequentially stacked BInGaN sublayers, composite sublayers, and BGaN sublayers. The composite sublayer is a periodic structure of alternating SiN and BN layers. The growth temperature gradient of the BInGaN sublayer, composite sublayer, and BGaN sublayer increases, and the In content of the BInGaN sublayer gradually decreases. This invention, through a special design of the cap layer in the multiple quantum well layers, effectively protects the In content of the quantum wells, reduces lattice mismatch in the well barrier, alleviates In segregation at the quantum well barrier interface, improves the interface crystal quality at the quantum well barrier, makes the well barrier interface steeper, which is beneficial for improving wavelength uniformity and obtaining better antistatic capabilities, and successfully improves the luminous efficiency of the light-emitting diode.

Description

Technical Field

[0001] This invention relates to the field of light-emitting diode technology, and in particular to a GaN-based light-emitting diode epitaxial wafer and its fabrication method. Background Technology

[0002] Currently, GaN-based light-emitting diodes (LEDs) are widely used due to their advantages such as high efficiency, energy saving, and environmental friendliness. The multiple quantum well structure, as the core region for light emission in blue-green LEDs, has received extensive research. Multiple quantum wells are generally composed of alternating layers of InGaN quantum wells and GaN quantum barriers. However, due to the lattice constant mismatch between the InGaN quantum well layers and the GaN quantum barrier layers, many defects are generated at the quantum well-barrier interface. Excessive defects in the multiple quantum wells cause In segregation and a significant increase in nonradiative complex nuclei, thus affecting their luminous efficiency.

[0003] To improve the crystal quality and reduce defects in multi-quantum-well layers, quantum barrier layers are typically grown at relatively high temperatures. However, InGaN quantum well layers are prone to decomposition at high temperatures. Therefore, excessively high quantum barrier growth temperatures can easily cause the desorption or decomposition of In atoms in the quantum well, affecting the incorporation of In into the quantum well layer and thus reducing luminescence efficiency. Therefore, a relatively low-temperature GaN cap layer is usually inserted between the quantum well layer and the quantum barrier layer as a protective layer for the quantum well.

[0004] However, while the introduction of the low-temperature GaN cap layer protects the In component in the quantum well and reduces the decomposition of In atoms, the low temperature also leads to insufficient ammonia cleavage, resulting in defects such as N vacancies. This causes more defects at the quantum well barrier interface, exacerbating In segregation and affecting the luminous efficiency of the LED, thus impacting its brightness. Summary of the Invention

[0005] Based on this, the purpose of this invention is to provide a GaN-based light-emitting diode epitaxial wafer and its fabrication method, aiming to solve at least one technical problem in the background art.

[0006] According to an embodiment of the present invention, a GaN-based light-emitting diode epitaxial wafer includes a multi-quantum-well layer, wherein the multi-quantum-well layer is a periodic structure in which quantum well layers, quantum well cap layers and quantum barrier layers are stacked alternately;

[0007] The quantum well cap layer comprises sequentially stacked BInGaN sublayers, composite sublayers, and BGaN sublayers. The composite sublayer is a periodic structure with alternating SiN and BN layers. The growth temperature gradient of the BInGaN sublayer, the composite sublayer, and the BGaN sublayer increases, and the In content of the BInGaN sublayer gradually decreases.

[0008] Preferably, the amount of H2 introduced during the growth of the BInGaN sublayer, the composite sublayer, and the BGaN sublayer increases.

[0009] Preferably, no H2 is introduced during the growth of the BInGaN sublayer, the amount of H2 introduced during the growth of the composite sublayer is 1-3L, and the amount of H2 introduced during the growth of the BGaN sublayer is 5-10L.

[0010] Preferably, the growth temperature of the BInGaN sublayer is 750–800°C, the growth temperature of the composite sublayer is 800–850°C, and the growth temperature of the BGaN sublayer is 850–900°C.

[0011] Preferably, the In component content in the BInGaN sublayer gradually decreases from 0.05-0.2 to 0, and the B component content in the BInGaN sublayer is 0.1-0.2.

[0012] Preferably, the Si component content in the SiN layer is 0.05-0.15, the B component content in the BN layer is 0.05-0.15, and the number of periods in the periodic structure of the composite sublayer is 1-5.

[0013] Preferably, the thickness of the BinGaN sublayer is 1-2 nm, the thickness of the composite sublayer is 1-3 nm, and the thickness of the BGaN sublayer is 3-5 nm.

[0014] Preferably, it further includes a substrate, a GaN low-temperature buffer layer, an undoped GaN layer, an N-type doped GaN layer, an electron blocking layer, and a p-type doped GaN layer;

[0015] The GaN low-temperature buffer layer, the undoped GaN layer, the N-type doped GaN layer, the multiple quantum well layer, the electron blocking layer, and the p-type doped GaN layer are sequentially grown on the substrate.

[0016] According to an embodiment of the present invention, a method for fabricating a GaN-based light-emitting diode epitaxial wafer is provided for fabricating the aforementioned GaN-based light-emitting diode epitaxial wafer. The fabrication method includes:

[0017] The quantum well layer, quantum well cap layer, and quantum barrier layer are periodically and alternately grown to prepare the multi-quantum well layer of the GaN-based light-emitting diode epitaxial wafer.

[0018] In the process of growing the quantum well layer, the source required for growing the quantum well layer is introduced into an atmosphere in which pure N2 is used as the carrier gas to grow the quantum well layer.

[0019] During the growth of the quantum well cap layer, in an atmosphere with pure N2 as the carrier gas, the source required for growing the BInGaN sublayer is first introduced to grow the BInGaN sublayer on the quantum well layer. Then, in an atmosphere with H2 and N2 as the carrier gas, the sources required for the SiN layer and BN layer are introduced to periodically and alternately grow the SiN layer and BN layer on the BInGaN sublayer to prepare a composite sublayer. Finally, in an atmosphere with H2 and N2 as the carrier gas, the source required for the BGaN sublayer is introduced to grow the BInGaN sublayer on the composite sublayer.

[0020] During the growth of the quantum barrier layer, a source required for the growth of the quantum barrier layer is introduced in an atmosphere in which H2 and N2 are used as carrier gases, so as to grow the quantum barrier layer on the quantum well cap layer.

[0021] Preferably, before periodically alternating the growth of quantum well layers, quantum well cap layers, and quantum barrier layers to prepare the multi-quantum well layer of the GaN-based light-emitting diode epitaxial wafer, the method further includes:

[0022] Provide a substrate required for epitaxial growth;

[0023] A GaN low-temperature buffer layer, an undoped GaN layer, and an N-type doped GaN layer are epitaxially grown sequentially on the substrate, and the multiple quantum well layer is grown on the N-type doped GaN layer;

[0024] After periodically growing alternating quantum well layers, quantum well cap layers, and quantum barrier layers to prepare the multi-quantum well layer of the GaN-based light-emitting diode epitaxial wafer, the process further includes:

[0025] An electron blocking layer and a p-type doped GaN layer are epitaxially grown sequentially on the multi-quantum-well layer.

[0026] Compared to existing technologies, this approach employs a composite quantum well cap layer composed of sequentially stacked BInGaN sublayers, composite sublayers, and BGaN sublayers. First, a BInGaN sublayer is grown on the quantum well layer. Due to the small size of B atoms, it can fill vacancies in the lattice, improving the crystal quality of this layer and reducing defect generation. Simultaneously, the In composition gradually decreases, primarily to achieve better lattice matching with the quantum well layer, forming a smooth transition of In composition and reducing In segregation. Then, a superlattice periodic structure (i.e., a composite sublayer) with overlapping BN and SiN layers is grown on the BInGaN sublayer. The smaller lattice size of SiN and BN materials repairs and shields dislocations and V-type defects, and also partially blocks In diffusion. Furthermore, the BN and SiN heterojunction generates a two-dimensional electron gas, which helps improve carrier mobility, thereby promoting electron-hole recombination within the quantum well and improving luminescence efficiency. The buffer provided by the BInGaN sublayer allows for a higher growth temperature, further contributing to improved lattice quality. Finally, a BGaN sublayer is grown on the composite sublayer, and the growth temperature is increased again. It has good lattice quality, tends to be two-dimensional, and has high flatness.

[0027] In summary, this invention, through a special design of the cap layer in the multi-quantum-well layer, not only effectively protects the In composition of the quantum well, but also helps reduce lattice mismatch of the well barrier, alleviates In segregation at the quantum well barrier interface, improves the interface crystal quality at the quantum well barrier, makes the well barrier interface steeper, which is conducive to improving wavelength uniformity and obtaining better antistatic ability, and successfully improves the luminous efficiency of the light-emitting diode, ultimately successfully improving the luminous brightness of the light-emitting diode. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the GaN-based light-emitting diode epitaxial wafer in Embodiment 1 of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the multi-quantum well layer in Embodiment 1 of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure of the quantum well cap layer in Embodiment 1 of the present invention.

[0031] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0032] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0033] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] Example 1

[0036] Please see Figures 1-3 The image shows a GaN-based light-emitting diode epitaxial wafer according to Embodiment 1 of the present invention, including a substrate 1, and a GaN low-temperature buffer layer 2, an undoped GaN layer 3, an N-type doped GaN layer 4, a multiple quantum well layer 5, an electron blocking layer 6, and a p-type doped GaN layer 7 sequentially epitaxially grown on the substrate 1.

[0037] In this embodiment, as Figure 2 As shown, the multiple quantum well layer 5 is a periodic structure consisting of alternating layers of quantum well layer 51, quantum well cap layer 52, and quantum barrier layer 53. The quantum well layer 51 can be an InGaN quantum well layer, and the quantum barrier layer 53 can be a GaN quantum barrier layer. The quantum well cap layer 52 is inserted between the quantum well layer 51 and the quantum barrier layer 53, primarily for protecting the In composition of the quantum wells and reducing lattice defects in the well barrier. Specifically, in this embodiment, as... Figure 3As shown, the quantum well cap layer 52 is a composite quantum well cap layer, comprising sequentially stacked BInGaN sublayer 521, composite sublayer 522, and BGaN sublayer 523. The composite sublayer 522 has a periodic structure with alternating SiN and BN layers. The growth temperature gradient of the BInGaN sublayer 521, composite sublayer 522, and BGaN sublayer 523 increases. Specifically, in this embodiment, the growth temperature of the BInGaN sublayer 521 is 750°C, the growth temperature of the composite sublayer 522 is 800°C, and the growth temperature of the BGaN sublayer 523 is 850°C. Furthermore, the In content of the BInGaN sublayer 521 gradually decreases, specifically, the In content in the BInGaN sublayer 521 gradually decreases from 0.05 to 0, and the B content in the BInGaN sublayer 521 is 0.1.

[0038] In this embodiment, a BInGaN sublayer 521 is first grown at a low temperature on the quantum well layer 51. Due to the small size of B atoms, they can fill the vacancies between the crystal lattice, improving the crystal quality of this layer and reducing the generation of defects. At the same time, the In composition gradually decreases, mainly to achieve better lattice matching with the quantum well layer 51, forming a smooth transition of In composition and reducing In segregation. Then, a superlattice periodic structure of overlapping BN and SiN layers (i.e., composite sublayer 522) is grown on the BInGaN sublayer 521. The small-sized SiN and BN materials have the effect of repairing and shielding the dislocations and V-type defects, and also have a certain blocking effect on the diffusion of In composition. At the same time, the BN and SiN heterojunction generates a two-dimensional electron gas, which helps to improve the carrier mobility, thereby promoting the recombination of electron-hole pairs in the quantum well and improving the luminescence efficiency. Because of the buffer provided by the BInGaN sublayer 521, the growth temperature of this layer is selected to be higher, which helps to improve the lattice quality. Finally, a BGaN sublayer 523 is grown on the composite sublayer 522, and the growth temperature is increased again. It has good lattice quality and high flatness.

[0039] In addition, in some preferred embodiments of this example, the amount of H2 introduced during the growth of the BInGaN sublayer 521, the composite sublayer 522, and the BGaN sublayer 523 is increased in a gradient. More specifically, no H2 is introduced during the growth of the BInGaN sublayer 521, the amount of H2 introduced during the growth of the composite sublayer 522 is 1L, and the amount of H2 introduced during the growth of the BGaN sublayer 523 is 5L. The purpose of not introducing H2 during the growth of the BInGaN sublayer 521 is that, since H2 has a certain etching effect, it will affect the incorporation of In in the quantum well, thereby causing a decrease in luminous efficiency. At the same time, it avoids the reduction of In composition in the quantum well layer 51 caused by direct contact between H2 and the quantum well layer 51, which would affect the luminous efficiency of the light-emitting diode. The purpose of introducing a small amount of H2 during the growth of the composite sublayer 522 is that it helps to improve the lattice quality, and the etching effect of H2 can also prevent the diffusion of In composition and reduce In "clusters". The purpose of introducing more H2 during the growth of the BGaN sublayer 523 is to further improve the lattice quality and make it more inclined to two-dimensional growth.

[0040] In addition, in some cases of this embodiment, the number of periods in the periodic structure of the composite sublayer 522 is 1-5, and each period consists of a SiN layer and a BN layer stacked sequentially. The Si content in the SiN layer is 0.05-0.15%, and the B content in the BN layer is 0.05-0.15%. Furthermore, the thickness of the BinGaN sublayer 521 is 1-2 nm, the thickness of the composite sublayer 522 is 1-3 nm, and the thickness of the BGaN sublayer 523 is 3-5 nm.

[0041] On the other hand, this embodiment also proposes a method for fabricating a GaN-based light-emitting diode epitaxial wafer, used to fabricate the GaN-based light-emitting diode epitaxial wafer in this embodiment. The fabrication method includes the following steps:

[0042] Step S11: Provide a substrate required for epitaxial growth, and perform high-temperature annealing treatment on the substrate at a temperature of 1050-1200℃ in an H2 atmosphere for 3-6 minutes.

[0043] The substrate is preferably a sapphire substrate.

[0044] Step 202: Grow a GaN low-temperature buffer layer on the substrate at a growth temperature of 500℃~700℃ and a growth pressure of 200~400 Torr.

[0045] For example, the thickness of the GaN low-temperature buffer layer can be 10–30 nm.

[0046] Step 203: Grow an undoped GaN layer on the GaN low-temperature buffer layer at a growth temperature of 1000–1150 °C and a pressure of 200–400 Torr.

[0047] For example, the thickness of the undoped GaN layer is about 1 to 5 μm.

[0048] Step 204: Grow an N-type doped GaN layer on the undoped GaN layer at a growth temperature of 1000–1150 °C and a growth pressure of 200–400 Torr.

[0049] For example, the N-type doped GaN layer is a Si-doped GaN layer with a thickness of about 1 to 3 μm.

[0050] Step 205: Periodically and alternately grow quantum well layers, quantum well cap layers, and quantum barrier layers on the N-type doped GaN layer to grow multiple quantum well layers on the N-type doped GaN layer.

[0051] During the growth of the quantum well layer, a source required for growing the quantum well layer is introduced under a pure N2 carrier gas atmosphere to grow the quantum well layer. During the growth of the quantum well cap layer, no H2 is introduced. Under a pure N2 carrier gas atmosphere and a growth temperature of 750°C, a source required for growing the BinGaN sublayer is first introduced, and the amount of In component introduced is gradually reduced to grow the BinGaN sublayer on the quantum well layer. Then, 1L of H2 is introduced, and the growth temperature is increased to 800°C. Under an atmosphere using both H2 and N2 as carrier gases, a source is introduced... The required sources for the SiN and BN layers are used to periodically and alternately grow SiN and BN layers on the BinGaN sublayer to prepare a composite sublayer. Finally, the H2 injection rate is increased to 5L, and the growth temperature is increased to 850℃. In an atmosphere with H2 and N2 as carrier gases, the source required for the BGaN sublayer is introduced to grow the BinGaN sublayer on the composite sublayer. When growing the quantum barrier layer, in an atmosphere with H2 and N2 as carrier gases, the source required for the growth of the quantum barrier layer is introduced to grow the quantum barrier layer on the quantum well cap layer.

[0052] For example, the growth temperature of the quantum well layers in the multi-quantum well layer can be 700-800°C, the period of the multi-quantum well can be 3-15 layers, and the growth pressure is 100-500 Torr; the thickness of each period of the quantum well layer is about 2-4 nm; the thickness of each period of the quantum barrier layer is 5-15 nm, and the growth temperature is 850-950°C.

[0053] Step 206: Grow an electron blocking layer on the multi-quantum well layer at a growth temperature of 800–1000 °C and a growth pressure of 100–300 Torr.

[0054] For example, the electron blocking layer may be a superlattice structure of GaN and ALGaN;

[0055] Step 207: Grow a P-type doped GaN layer on the electron blocking layer at a growth temperature of approximately 800–1000 °C and a growth pressure of 100–300 torr.

[0056] For example, the P-type doped GaN layer can be a Mg-doped GaN layer with a thickness of about 50 to 300 nm.

[0057] Example 2

[0058] Embodiment 2 of the present invention also proposes a GaN-based light-emitting diode epitaxial wafer and its preparation method. The difference between the GaN-based light-emitting diode epitaxial wafer and its preparation method in this embodiment and those in Embodiment 1 is as follows:

[0059] No H2 is introduced during BInGaN sublayer growth, while 2L of H2 is introduced during composite sublayer growth and 8L of H2 is introduced during BGaN sublayer growth.

[0060] Example 3

[0061] Embodiment 3 of the present invention also proposes a GaN-based light-emitting diode epitaxial wafer and its preparation method. The difference between the GaN-based light-emitting diode epitaxial wafer and its preparation method in this embodiment and those in Embodiment 1 is as follows:

[0062] No H2 is introduced during BInGaN sublayer growth, while 3L of H2 is introduced during composite sublayer growth and 10L of H2 is introduced during BGaN sublayer growth.

[0063] Example 4

[0064] Embodiment 4 of this invention also proposes a GaN-based light-emitting diode epitaxial wafer and its fabrication method. The difference between the GaN-based light-emitting diode epitaxial wafer and its fabrication method in this embodiment and those in Embodiment 1 is as follows:

[0065] The growth temperature of the BInGaN sublayer is 780℃, the growth temperature of the composite sublayer is 830℃, and the growth temperature of the BGaN sublayer is 880℃.

[0066] Example 5

[0067] Embodiment 5 of the present invention also proposes a GaN-based light-emitting diode epitaxial wafer and its preparation method. The difference between the GaN-based light-emitting diode epitaxial wafer and its preparation method in this embodiment and those in Embodiment 1 is as follows:

[0068] The growth temperature for the BInGaN sublayer is 800℃, the growth temperature for the composite sublayer is 850℃, and the growth temperature for the BGaN sublayer is 900℃.

[0069] Example 6

[0070] Embodiment Six of this invention also proposes a GaN-based light-emitting diode epitaxial wafer and its fabrication method. The difference between the GaN-based light-emitting diode epitaxial wafer and its fabrication method in this embodiment and those in Embodiment One is as follows:

[0071] The In content in the BInGaN sublayer gradually decreases from 0.1 to 0.

[0072] Example 7

[0073] Embodiment 7 of the present invention also proposes a GaN-based light-emitting diode epitaxial wafer and its preparation method. The difference between the GaN-based light-emitting diode epitaxial wafer and its preparation method in this embodiment and those in Embodiment 1 is as follows:

[0074] The In content in the BInGaN sublayer gradually decreases from 0.2 to 0.

[0075] Example 8

[0076] Embodiment 8 of the present invention also proposes a GaN-based light-emitting diode epitaxial wafer and its preparation method. The difference between the GaN-based light-emitting diode epitaxial wafer and its preparation method in this embodiment and those in Embodiment 1 is as follows:

[0077] The B component content in the BInGaN sublayer is 0.2%.

[0078] Comparative Example 1

[0079] In Comparative Example 1 of this invention, a GaN-based light-emitting diode epitaxial wafer and its fabrication method are also proposed. The difference between the GaN-based light-emitting diode epitaxial wafer and its fabrication method in this embodiment and the GaN-based light-emitting diode epitaxial wafer and its fabrication method in Example 1 is as follows:

[0080] In Comparative Example 1, no H2 was introduced during the entire growth process of the quantum well cap layer.

[0081] Comparative Example 2

[0082] In Comparative Example 2 of this invention, a GaN-based light-emitting diode epitaxial wafer and its fabrication method are also proposed. The difference between the GaN-based light-emitting diode epitaxial wafer and its fabrication method in this embodiment and the GaN-based light-emitting diode epitaxial wafer and its fabrication method in Example 1 is as follows:

[0083] In Comparative Example 1, 8L of H2 was introduced throughout the growth process of the quantum well cap layer.

[0084] Comparative Example 3

[0085] In Comparative Example 3 of this invention, a GaN-based light-emitting diode epitaxial wafer and its fabrication method are also proposed. The difference between the GaN-based light-emitting diode epitaxial wafer and its fabrication method in this embodiment and the GaN-based light-emitting diode epitaxial wafer and its fabrication method in Example 1 is as follows:

[0086] The In content in the BInGaN sublayer is fixed at 0.2 and does not decrease gradually.

[0087] Comparative Example 4

[0088] In Comparative Example 4 of this invention, a GaN-based light-emitting diode epitaxial wafer and its fabrication method are also proposed. The difference between the GaN-based light-emitting diode epitaxial wafer and its fabrication method in this embodiment and the GaN-based light-emitting diode epitaxial wafer and its fabrication method in Example 1 is as follows:

[0089] The quantum well cap layer in Comparative Example 4 is a traditional low-temperature GaN cap layer.

[0090] Please refer to Table 1 below, which shows the parameters corresponding to Embodiments 1-8 and Comparative Examples 1-4 of the present invention.

[0091] Table 1

[0092]

[0093] In Table 1 above, “→” represents a change. For example, 0.05→0 means that the In component content in the BInGaN sublayer gradually decreases from 0.05 to 0. Another example is 0→1→5, which means that the H2 injection rate of the quantum well cap layer changes from no H2 injection to 1L H2 injection and then to 5L H2 injection.

[0094] In practical applications, GaN-based light-emitting diode epitaxial wafers were prepared using the preparation methods and parameters corresponding to Examples 1-8 and Comparative Examples 1-4 of the present invention, respectively. The luminous brightness, wavelength uniformity, and electrostatic discharge (ESD) transmittance of the GaN-based light-emitting diode epitaxial wafers prepared in each example were tested, and the test data are shown in Table 2 below. It should be noted that, to ensure the reliability of the verification results, the preparation of epitaxial wafers for Examples 1-8 and Comparative Examples 1-4 of the present invention should be identical except for the aforementioned parameters. For example, the preparation processes and parameters of the other layers, except for the multi-quantum-well layer, should be kept consistent.

[0095] Table 2:

[0096]

[0097] Combining the data in Tables 1 and 2 above, it is evident that the multilayer composite quantum well cap layer used in this embodiment of the invention significantly improves luminous brightness and wavelength uniformity, indicating that defects at the well-barrier interface are greatly reduced. Simultaneously, the antistatic capability is also significantly enhanced. This demonstrates that the invention effectively protects the In composition of the quantum well, reduces defects within the quantum well, reduces non-radiative recombination, and ensures luminous efficiency. Furthermore, it helps reduce lattice mismatch at the well-barrier, alleviates In segregation at the quantum well-barrier interface, improves the interface crystal quality at the quantum well-barrier, making the well-barrier interface steeper. This contributes to improved wavelength uniformity and better antistatic capability, and successfully enhances the luminous brightness of the light-emitting diode.

[0098] In summary, the GaN-based light-emitting diode epitaxial wafer and its fabrication method in this invention employ a composite quantum well cap layer composed of a BInGaN sublayer, a composite sublayer, and a BGaN sublayer stacked sequentially. A BInGaN sublayer is first grown on the quantum well layer. Due to the small size of B atoms, they can fill vacancies in the lattice, improving the crystal quality of this layer and reducing defect generation. Simultaneously, the In composition gradually decreases, primarily to achieve better lattice matching with the quantum well layer, forming a smooth transition in In composition and reducing In segregation. Then, a superlattice periodic structure (i.e., a composite sublayer) with overlapping BN and SiN layers is grown on the BInGaN sublayer. The smaller lattice size of the SiN and BN materials helps repair and shield the dislocations and V-type defects in the preceding layer, and also blocks the diffusion of In. At the same time, the BN and SiN heterojunction generates a two-dimensional electron gas, which helps to improve carrier mobility, thereby promoting electron-hole recombination in the quantum well and improving luminescence efficiency. Because of the buffer provided by the BInGaN sublayer, the growth temperature can be increased in this section, which helps to improve the lattice quality. Finally, a BGaN sublayer is grown on the composite sublayer, and the growth temperature is increased again. This structure itself has good lattice quality, is more inclined to two-dimensional growth, and has high flatness.

[0099] In summary, this invention, through a special design of the cap layer in the multi-quantum-well layer, not only effectively protects the In composition of the quantum well, but also helps reduce the lattice mismatch of the well barrier, alleviates the segregation of In at the quantum well barrier interface, improves the interface crystal quality at the quantum well barrier, makes the well barrier interface steeper, which is conducive to improving wavelength uniformity and obtaining better antistatic ability, and successfully improves the luminous efficiency of the light-emitting diode.

[0100] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A GaN-based light-emitting diode epitaxial wafer, characterized in that, It includes a multi-quantum-well layer, wherein the multi-quantum-well layer is a periodic structure in which quantum well layers, quantum well cap layers and quantum barrier layers are stacked alternately; The quantum well cap layer comprises a BInGaN sublayer, a composite sublayer, and a BGaN sublayer stacked sequentially. The composite sublayer is a periodic structure with alternating SiN and BN layers. The growth temperature of the BInGaN sublayer, the composite sublayer, and the BGaN sublayer increases in a gradient, and the In content of the BInGaN sublayer gradually decreases along its growth direction.

2. The GaN-based light-emitting diode epitaxial wafer according to claim 1, characterized in that, The amount of H2 introduced during the growth of the BInGaN sublayer, the amount of H2 introduced during the growth of the composite sublayer, and the amount of H2 introduced during the growth of the BGaN sublayer increase in a gradient order.

3. The GaN-based light-emitting diode epitaxial wafer according to claim 2, characterized in that, No H2 is introduced during the growth of the BInGaN sublayer, the amount of H2 introduced during the growth of the composite sublayer is 1-3L, and the amount of H2 introduced during the growth of the BGaN sublayer is 5-10L.

4. The GaN-based light-emitting diode epitaxial wafer according to claim 1, characterized in that, The growth temperature of the BInGaN sublayer is 750-800℃, the growth temperature of the composite sublayer is 800-850℃, and the growth temperature of the BGaN sublayer is 850-900℃.

5. The GaN-based light-emitting diode epitaxial wafer according to claim 1, characterized in that, The In component content in the BInGaN sublayer gradually decreases from 0.05-0.2 to 0, and the B component content in the BInGaN sublayer is 0.1-0.

2.

6. The GaN-based light-emitting diode epitaxial wafer according to claim 1, characterized in that, The Si component content in the SiN layer is 0.05-0.15%, the B component content in the BN layer is 0.05-0.15%, and the period number of the periodic structure of the composite sublayer is 1-5.

7. The GaN-based light-emitting diode epitaxial wafer according to claim 1, characterized in that, The thickness of the BinGaN sublayer is 1-2 nm, the thickness of the composite sublayer is 1-3 nm, and the thickness of the BGaN sublayer is 3-5 nm.

8. The GaN-based light-emitting diode epitaxial wafer according to any one of claims 1-7, characterized in that, It also includes a substrate, a GaN low-temperature buffer layer, an undoped GaN layer, an N-type doped GaN layer, an electron blocking layer, and a p-type doped GaN layer; The GaN low-temperature buffer layer, the undoped GaN layer, the N-type doped GaN layer, the multiple quantum well layer, the electron blocking layer, and the p-type doped GaN layer are sequentially grown on the substrate.

9. A method for fabricating a GaN-based light-emitting diode epitaxial wafer, characterized in that, The method for preparing the GaN-based light-emitting diode epitaxial wafer according to any one of claims 1-8 comprises: The quantum well layer, quantum well cap layer, and quantum barrier layer are periodically and alternately grown to prepare the multi-quantum well layer of the GaN-based light-emitting diode epitaxial wafer. In the process of growing the quantum well layer, the source required for growing the quantum well layer is introduced into an atmosphere in which pure N2 is used as the carrier gas to grow the quantum well layer. During the growth of the quantum well cap layer, in an atmosphere with pure N2 as the carrier gas, the source required for growing the BInGaN sublayer is first introduced to grow the BInGaN sublayer on the quantum well layer. Then, in an atmosphere with H2 and N2 as the carrier gas, the sources required for the SiN layer and BN layer are introduced to periodically and alternately grow the SiN layer and BN layer on the BInGaN sublayer to prepare a composite sublayer. Finally, in an atmosphere with H2 and N2 as the carrier gas, the source required for the BGaN sublayer is introduced to grow the BInGaN sublayer on the composite sublayer. During the growth of the quantum barrier layer, a source required for the growth of the quantum barrier layer is introduced in an atmosphere in which H2 and N2 are used as carrier gases, so as to grow the quantum barrier layer on the quantum well cap layer.

10. The method for fabricating a GaN-based light-emitting diode epitaxial wafer according to claim 9, characterized in that, Before the periodic alternating growth of quantum well layers, quantum well cap layers, and quantum barrier layers to prepare the multi-quantum well layer of the GaN-based light-emitting diode epitaxial wafer, the process further includes: Provide a substrate required for epitaxial growth; A GaN low-temperature buffer layer, an undoped GaN layer, and an N-type doped GaN layer are epitaxially grown sequentially on the substrate, and the multiple quantum well layer is grown on the N-type doped GaN layer; After periodically growing alternating quantum well layers, quantum well cap layers, and quantum barrier layers to prepare the multi-quantum well layer of the GaN-based light-emitting diode epitaxial wafer, the process further includes: An electron blocking layer and a p-type doped GaN layer are epitaxially grown sequentially on the multi-quantum-well layer.

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