Light emitting diode epitaxial wafer and method of manufacturing the same

Abstract

This invention discloses a light-emitting diode epitaxial wafer and its fabrication method, relating to the field of light-emitting diode technology. The light-emitting diode epitaxial wafer includes a substrate; a buffer layer, an undoped GaN layer, a defect blocking layer, an N-type GaN layer, a light-emitting layer, an electron blocking layer, a P-type GaN layer, and a contact layer are sequentially disposed on the substrate; wherein the defect blocking layer sequentially includes a first defect blocking layer, a second defect blocking layer, and a third defect blocking layer, and the first defect blocking layer is Al. a Ga 1‑a The first defect barrier layer is an N-type thin film, the second defect barrier layer is a BN-type thin film, and the third defect barrier layer is an Al-type thin film. a Ga 1‑a N-film layer. This invention solves the technical problem in the prior art where a large lattice mismatch between the substrate and the epitaxial layer leads to an increase in the dislocation density of the epitaxial layer, affecting the luminous efficiency and photoelectric performance of the LED epitaxial wafer.

Description

Technical Field

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

[0002] With the development of semiconductor technology, light-emitting diodes (LEDs) have made significant progress over the past 100 years. An LED is a photoelectric device that converts electrical energy into light energy. It boasts advantages such as energy efficiency, environmental friendliness, and long lifespan, and is widely used in various fields, including indicator lights, LED billboards, displays, and general lighting. Therefore, LEDs have a promising future.

[0003] Currently, the most common epitaxial structure for light-emitting diodes (LEDs) is heteroepitaxial growth on a sapphire substrate, where the substrate material and the epitaxial layer material are different. However, the lattice constant of the sapphire (Al2O3) substrate for LED epitaxial wafers is 0.4785, while the lattice constant of the epitaxial layer (GaN) is 0.3189, a significant difference. Due to the large lattice mismatch, the GaN epitaxial layer grown on the sapphire substrate will experience a decrease in crystal quality, an increase in dislocation density, and dislocations will extend along the growth direction of the epitaxial layer. This leads to a decrease in the crystal quality of the LED's light-emitting layer, an increase in non-radiative recombination, and a decline in luminous efficiency and photoelectric performance.

[0004] Therefore, existing LED epitaxial wafers generally suffer from a large lattice mismatch between the substrate and the epitaxial layer, resulting in an increased dislocation density in the epitaxial layer, which affects the luminous efficiency and photoelectric performance of the LED epitaxial wafer. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a light-emitting diode epitaxial wafer and its fabrication method, thereby solving the technical problem that a large lattice mismatch between the substrate and the epitaxial layer in the prior art leads to an increase in the dislocation density of the epitaxial layer, which affects the luminous efficiency and photoelectric performance of the light-emitting diode epitaxial wafer.

[0006] One aspect of the present invention is to provide a light-emitting diode epitaxial wafer, the light-emitting diode epitaxial wafer comprising:

[0007] Substrate;

[0008] A buffer layer, an undoped GaN layer, a defect blocking layer, an N-type GaN layer, a light-emitting layer, an electron blocking layer, a P-type GaN layer, and a contact layer are sequentially disposed on the substrate.

[0009] The defect barrier layer comprises, in sequence, a first defect barrier layer, a second defect barrier layer, and a third defect barrier layer, wherein the first defect barrier layer is Al. a Ga 1-aThe first defect barrier layer is an N-type thin film layer, the second defect barrier layer is a BN-type thin film layer, and the third defect barrier layer is an Al-type thin film layer. a Ga 1-a N thin film layer.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a light-emitting diode epitaxial wafer by inserting a three-layer defect blocking layer, which reduces the dislocation density of the light-emitting diode epitaxial wafer. Specifically, the defect blocking layer includes a first defect blocking layer, a second defect blocking layer, and a third defect blocking layer. The first and second defect blocking layers prevent dislocations and defects formed by lattice mismatch from extending and expanding towards the epitaxial layer growth direction, effectively suppressing the extension of dislocations and defects to the light-emitting layer, improving radiative recombination of the light-emitting layer, and enhancing the luminous efficiency of the light-emitting diode epitaxial wafer. The third defect blocking layer reduces the lattice mismatch between the second defect blocking layer and the N-type GaN layer, improving the crystal quality of the N-type GaN layer, thereby improving the crystal quality of the light-emitting diode epitaxial wafer, reducing dislocation and defect density, and improving the luminous efficiency and photoelectric performance of the light-emitting diode epitaxial wafer. This solves the technical problem that a large lattice mismatch between the substrate and the epitaxial layer leads to an increase in the dislocation density of the epitaxial layer, affecting the luminous efficiency and photoelectric performance of the light-emitting diode epitaxial wafer.

[0011] According to one aspect of the above technical solution, the Al component concentration of the first defect blocking layer and the second defect blocking layer is the same, and the Al component ratio is 0.005-0.1%.

[0012] According to one aspect of the above technical solution, the thickness of the defect blocking layer is 10-50nm, and the thickness ratio of the first defect blocking layer, the second defect blocking layer and the third defect blocking layer is 1:1:1 to 1:10:1.

[0013] According to one aspect of the above technical solution, the buffer layer is an AlN thin film layer with a thickness of 10-20 nm.

[0014] According to one aspect of the above technical solution, the light-emitting layer is a multi-quantum-well structure, comprising several periods of InGaN quantum well layers and Al... b Ga 1-b N-quantum barrier layer.

[0015] According to one aspect of the above technical solution, the thickness of the InGaN quantum well layer is 2-3.5 nm, and the Al b Ga 1- b The thickness of the N quantum barrier layer is 9-12 nm, in which the Al component accounts for 0.05-0.2%.

[0016] According to one aspect of the above technical solution, the electron blocking layer is Al. c Ind Ga 1-c-d The N thin film layer has a thickness of 10-40 nm, in which the Al component accounts for 0.005-0.1% (c) and the In component accounts for 0.05-0.2% (d).

[0017] According to one aspect of the above technical solution, the contact layer is a MgGaN thin film with a thickness of 5-20 nm, and the dopant of the contact layer is magnesium with a doping concentration of 1E21cm⁻¹. -3 -5E21 cm -3 between.

[0018] Another aspect of the present invention is to provide a method for fabricating a light-emitting diode epitaxial wafer, the method comprising:

[0019] Provide a substrate;

[0020] A buffer layer and an undoped GaN layer are sequentially grown on the substrate.

[0021] A defect barrier layer is epitaxially grown on the undoped GaN layer, wherein the defect barrier layer sequentially comprises a first defect barrier layer, a second defect barrier layer, and a third defect barrier layer, wherein the first defect barrier layer is Al. a Ga 1-a The first defect barrier layer is an N-type thin film layer, the second defect barrier layer is a BN-type thin film layer, and the third defect barrier layer is an Al-type thin film layer. a Ga 1-a N thin film layer;

[0022] An N-type GaN layer, a light-emitting layer, an electron-blocking layer, a P-type GaN layer, and a contact layer are sequentially epitaxially grown on the defect blocking layer.

[0023] To further explain, the growth steps of the defect barrier layer include:

[0024] The temperature is heated to between 950-1150℃ and the pressure is adjusted to between 100-400 Torr, and the first defect barrier layer, the second defect barrier layer and the third defect barrier layer are epitaxially grown sequentially.

[0025] Wherein, the first defect barrier layer is Al a Ga 1-a The first defect barrier layer is an N-type thin film layer, the second defect barrier layer is a BN-type thin film layer, and the third defect barrier layer is an Al-type thin film layer. a Ga 1-a N thin film layer. Attached Figure Description

[0026] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0027] Figure 1 This is a schematic diagram of the structure of the epitaxial wafer of the light-emitting diode in the first embodiment of the present invention;

[0028] Figure 2 This is a flowchart illustrating the method for fabricating a light-emitting diode epitaxial wafer in the second embodiment of the present invention.

[0029] Component symbol explanation in the attached diagram:

[0030] Substrate 100, buffer layer 200, undoped GaN layer 300, defect blocking layer 400, first defect blocking layer 401, second defect blocking layer 402, third defect blocking layer 403, N-type GaN layer 500, light-emitting layer 600, electron blocking layer 700, P-type GaN layer 800, contact layer 900. Detailed Implementation

[0031] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0032] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0033] In this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0034] Example 1

[0035] Please see Figure 1The image shows a light-emitting diode epitaxial wafer provided in the first embodiment of the present invention. The light-emitting diode epitaxial wafer includes a substrate 100, a buffer layer 200, an undoped GaN layer 300, a defect blocking layer 400, an N-type GaN layer 500, a light-emitting layer 600, an electron blocking layer 700, a P-type GaN layer 800, and a contact layer 900.

[0036] The substrate 100 serves as the substrate for the growth and support of the epitaxial layer. Different substrate 100 materials determine different epitaxial growth techniques and chip fabrication techniques. Currently, the substrate 100 for light-emitting diode epitaxial wafers includes sapphire substrates, silicon substrates, silicon carbide substrates, gallium nitride substrates, and zinc oxide substrates. In this embodiment, the substrate 100 material is sapphire. Sapphire substrates are widely used in the production of light-emitting diode epitaxial wafers due to their simple and mature fabrication process, low cost, and good chemical and thermal stability.

[0037] A buffer layer 200 is provided on the sapphire substrate 100. The buffer layer 200 is used to alleviate the lattice mismatch between the epitaxial layer and the substrate 100, so as to facilitate the growth of subsequent epitaxial layers and improve the crystal quality of subsequent epitaxial layers. The buffer layer 200 is an AlN thin film layer, which is grown by physical vapor deposition (PVD) to form an AlN thin film layer with a thickness of 10-20 nm. Physical vapor deposition (PVD) technology refers to the technology of vaporizing the surface of a material source (solid or liquid) into gaseous atoms or molecules, or partially ionizing them into ions, under vacuum conditions using physical methods, and depositing a thin film with a certain special function on the surface of a substrate through a low-pressure gas (or plasma) process.

[0038] An undoped GaN layer 300 is provided on the AlN buffer layer 200. The undoped GaN layer 300 is epitaxially grown using metal-organic chemical vapor deposition (MOCVD). MOCVD uses organic compounds of group III and II elements and hydrides of group V and VI elements as crystal growth source materials, and performs vapor-phase epitaxy on the substrate 100 via thermal decomposition reactions to grow thin single-crystal materials of various group III-V and group II-VI compound semiconductors and their multi-component solid solutions. The presence of the undoped GaN layer 300 on the AlN buffer layer 200 improves the crystal quality of the undoped GaN layer 300 epitaxial growth, reduces through-dislocations caused by the poor crystal quality of the AlN buffer layer 200, and improves the performance of the light-emitting diode epitaxial wafer.

[0039] Specifically, the temperature is heated to between 1000-1200℃ and the pressure is adjusted to between 150-200 Torr, and an undoped GaN layer 300 with a thickness of 2-3 μm is epitaxially grown on the AlN buffer layer 200.

[0040] Additionally, a defect barrier layer 400 is provided on the undoped GaN layer 300. This defect barrier layer 400 includes a first defect barrier layer 401, a second defect barrier layer 402, and a third defect barrier layer 403. The first defect barrier layer 401 is Al. a Ga 1-a The second defect barrier layer 402 is a BN thin film layer, and the third defect barrier layer 403 is an Al thin film layer. a Ga 1-a N thin film layer. The first defect barrier layer 401 and the third defect barrier layer 403 have the same material, thickness, and Al composition ratio, which can reduce lattice mismatch between the epitaxial layer and the substrate 100. Simultaneously, the Al composition ratio 'a' of the first defect barrier layer 401 and the third defect barrier layer 403 is 0.005-0.1. Since the radius of Al atoms is smaller than that of Ga atoms, the surface diffusion length of Al atoms is smaller, leading to parasitic reactions during epitaxial growth and reducing Al content. a Ga 1-a The crystal quality of the N thin film layer is good, while the Al content of the first defect barrier layer 401 and the second defect barrier layer 402 is relatively low, which can effectively prevent Al a Ga 1-a Parasitic reactions during the epitaxial growth of the N thin film layer improve the crystal quality of the first defect barrier layer 401 and the second defect barrier layer 402.

[0041] The defect blocking layer 400 has a thickness of 10-50 nm. In order to reduce the lattice matching degree between the defect blocking layer 400 and the undoped GaN layer 300 and the N-type GaN layer 500, the thickness ratio of the first defect blocking layer 401, the second defect blocking layer 402 and the third defect blocking layer 403 is 1:1:1 to 1:10:1. The thickness ratio and design of the three layers of the defect blocking layer 400 can effectively adapt to the lattice constant of the undoped GaN layer 300 and the N-type GaN layer 500, and improve the crystal quality of the light-emitting diode epitaxial wafer.

[0042] In addition, the first defect barrier layer 401 is disposed on the undoped GaN layer 300, which is Al a Ga 1-aThe N-film layer effectively mitigates lattice mismatch with the undoped GaN layer 300, while simultaneously preventing dislocations and defects caused by the substrate 100, buffer layer 200, and undoped GaN from extending and expanding towards the subsequent epitaxial layer growth direction. Specifically, the temperature is adjusted to between 950-1150℃, and the pressure is adjusted to between 100-400 Torr, for epitaxial growth of Al on the undoped GaN layer 300. a Ga 1-a The N-film layer serves as the first defect barrier layer 401, and Al is epitaxially grown under higher temperature and lower pressure. a Ga 1-a The N thin film layer helps to increase the surface diffusion length of Al atoms, further reduce the parasitic reactions of Al atoms, and improve the crystal quality of the first defect barrier layer 401.

[0043] Naturally, the second defect blocking layer 402 is disposed on the first defect blocking layer 401. It is a BN thin film layer. Since the radius of a B atom is smaller than that of an Al atom, and the density and crystal quality of the BN thin film layer are better than those of Al, the BN thin film layer is suitable for this purpose. a Ga 1-a The N-type thin film layer and the BN-type thin film layer can effectively fill the dislocation and defect sites that cannot be blocked in the first defect blocking layer 401, further suppressing the extension of dislocations and defects to subsequent epitaxial layers, improving the crystal quality of subsequent epitaxial layers, and thus improving the luminous efficiency and photoelectric performance of the light-emitting diode epitaxial wafer. Specifically, the temperature is adjusted to between 950-1150℃ and the pressure is adjusted to between 100-400 Torr, and a BN thin film layer is epitaxially grown on the first defect blocking layer 401 as the second defect blocking layer 402.

[0044] In addition, a third defect barrier layer 403 is disposed on the second defect barrier layer 402, and it is Al a Ga 1-a The N-type thin film layer mitigates the lattice mismatch between the second defect barrier layer 402 and the N-type GaN layer 500, i.e., it reduces the lattice mismatch between the BN thin film layer and the N-type GaN layer 500, thereby reducing dislocations and defects caused by lattice mismatch and improving the crystal quality of the N-type GaN layer 500, and thus improving the crystal quality of the LED epitaxial wafer. Specifically, the temperature is adjusted to between 950-1150℃ and the pressure is adjusted to between 100-400 Torr, and Al is epitaxially grown on the second defect barrier layer 402. a Ga 1-a The N-thickness thin film layer serves as the third defect barrier layer 403.

[0045] In this process, an N-type GaN layer 500 is provided on the defect blocking layer 400. This N-type GaN layer 500 has excess electrons, which are provided to the light-emitting layer 600, where radiative recombination of electrons and holes is achieved. Epitaxially growing the N-type GaN layer 500 on the defect blocking layer 400 can block dislocations and defects caused by lattice mismatch, effectively suppressing the extension of dislocations and defects into the N-type GaN layer 500, improving the crystal quality of the N-type GaN layer, thereby improving the effective radiative recombination of the light-emitting layer 600, and improving the luminous efficiency and photoelectric performance of the LED epitaxial wafer. Specifically, the temperature is heated to between 950-1150℃, and the pressure is adjusted to between 100-600 Torr, to epitaxially grow an N-type GaN layer 500 with a thickness of 2-3 μm on the defect blocking layer 400. The dopant of the N-type GaN layer 500 is silicon (Si), with a doping concentration of 1.6E19 cm⁻¹. -3 -5E19cm -3 between.

[0046] In addition, a light-emitting layer 600 is provided on the N-type GaN layer 500. The N-type GaN layer 500 provides electrons to the light-emitting layer 600, and the P-type GaN layer 800 provides holes to the light-emitting layer 600, so that electrons and holes can achieve radiative recombination and emission on the light-emitting layer 600. The light-emitting layer 600 has a multi-quantum-well structure, which includes several periodically stacked quantum well layers and quantum barrier layers, with a stacking period of 6-12. Among them, the quantum well layers are InGaN quantum well layers, with a growth temperature between 790-810℃ and a thickness of 2-3.5nm for a single InGaN quantum well layer, while the quantum barrier layer is Al. b Ga 1-b The N quantum barrier layer, with a growth temperature between 850-900℃, contains a single Al b Ga 1-b The thickness of the N quantum barrier layer is 9-12 nm, in which the Al component accounts for 0.05-0.2%.

[0047] An electron blocking layer 700 is provided on the N-type GaN layer 500. Since the electron migration rate is greater than the hole migration rate, electrons migrate to the P-type GaN layer 800, where non-radiative recombination occurs, reducing the luminous efficiency of the LED epitaxial wafer. The electron blocking layer 700 can block electrons from migrating from the N-type GaN layer 500 to the P-type GaN layer 800, thus blocking electrons in the light-emitting layer 600 region. This enhances the effective radiative recombination of electrons and holes in the multiple quantum well layers of the light-emitting layer 600, improving the luminous efficiency of the LED epitaxial wafer. This electron blocking layer 700 is an Al layer with a thickness of 10-40 nm. c In d Ga 1-c-dThe N thin film layer is grown at a temperature between 900-1000℃, wherein the component proportion of Al is c = 0.05-0.1 and the component proportion of In is d = 0.05-0.2.

[0048] Among them, in Al c In d Ga 1-c-d A p-type GaN layer 800 is disposed on the N-type electron blocking layer 700. The p-type GaN layer 800 has excess holes, which are provided to the light-emitting layer 600 to achieve radiative recombination luminescence of electrons and holes in the multiple quantum wells of the light-emitting layer 600. Specifically, the temperature is adjusted to between 900-1000℃ and the pressure is adjusted to between 100-600 Torr, in Al c In d Ga 1-c-d A p-type doped GaN layer is epitaxially grown on the N-electron blocking layer 700. The dopant in the p-type doped GaN layer is magnesium (Mg), and its doping concentration is 1E19cm⁻¹. -3 -1E20cm -3 between.

[0049] Naturally, a contact layer 900 is provided on the p-type GaN layer 800 to form an ohmic contact with the electrode, effectively reducing voltage and improving brightness. Specifically, the temperature is heated to between 850-950℃ and the pressure is adjusted to between 100-400 Torr to epitaxially grow a contact layer 900 with a thickness of 5-20 nm on the p-type GaN layer 800. The dopant of the contact layer 900 is magnesium (Mg), and its doping concentration is 1E21cm⁻¹. -3 -5E21cm -3 between.

[0050] It should be noted that when an external electric field is applied to both ends of the LED epitaxial wafer, with the N-type GaN layer 500 as the negative electrode and the P-type GaN layer 800 as the positive electrode, the N-type GaN layer 500 has excess electrons and the P-type GaN layer 800 has excess holes. Electrons in the N-type GaN layer 500 migrate towards the positive electrode P-type GaN layer 800, while holes in the P-type GaN layer 800 migrate towards the negative electrode N-type GaN layer 500. The migrated electrons and holes at both ends meet in the light-emitting layer 600, that is, electron-hole radiative recombination occurs in the multiple quantum wells, thereby realizing the light emission of the LED epitaxial wafer.

[0051] In this embodiment, two samples were fabricated using the same process and conditions to create 10mil*24mil chips. One sample did not have the defect blocking layer 400 inserted, while the other sample had the defect blocking layer 400 inserted. 300 LED epitaxial wafer chips were randomly selected from each sample and tested at 120mA / 60mA currents. The sample with the defect blocking layer 400 inserted showed a 0.5%-5% increase in brightness, a 0.5%-5% increase in Ir yield (leakage yield), and a 1%-5% increase in ESD yield (electrostatic discharge breakdown yield) compared to the sample without the defect blocking layer 400 inserted. Other electrical properties were also good.

[0052] Compared to existing technologies, the LED epitaxial wafer provided in this embodiment has the following advantages: By inserting a three-layer defect blocking layer, the dislocation density of the LED epitaxial wafer is reduced. Specifically, the defect blocking layer includes a first defect blocking layer, a second defect blocking layer, and a third defect blocking layer. The first and second defect blocking layers prevent dislocations and defects caused by lattice mismatch from extending and expanding towards the epitaxial layer growth direction, effectively suppressing the extension of dislocations and defects to the light-emitting layer, improving radiative recombination of the light-emitting layer, and enhancing the luminous efficiency of the LED epitaxial wafer. The third defect blocking layer reduces the lattice mismatch between the second defect blocking layer and the N-type GaN layer, improving the crystal quality of the N-type GaN layer, thereby improving the crystal quality of the LED epitaxial wafer, reducing dislocation and defect density, and enhancing the luminous efficiency and photoelectric performance of the LED epitaxial wafer. This solves the common technical problem of large lattice mismatch between the substrate and the epitaxial layer, leading to increased dislocation density in the epitaxial layer and affecting the luminous efficiency and photoelectric performance of the LED epitaxial wafer.

[0053] Example 2

[0054] Please see Figure 2 The image shows a method for fabricating a light-emitting diode epitaxial wafer according to a second embodiment of the present invention, the method comprising steps S10-S13:

[0055] Step S10: Provide a substrate;

[0056] The substrate is the base material on which the epitaxial layer grows and is supported. Different substrate materials determine different epitaxial growth techniques and chip fabrication techniques. Currently, substrates for light-emitting diode (LED) epitaxial wafers include sapphire substrates, silicon substrates, silicon carbide substrates, gallium nitride substrates, and zinc oxide substrates. In this embodiment, the substrate material is sapphire. Sapphire substrates are widely used in the production of LED epitaxial wafers due to their simple and mature fabrication process, low cost, and good chemical and thermal stability.

[0057] Step S11: A buffer layer and an undoped GaN layer are sequentially grown on the substrate;

[0058] In this process, a buffer layer, which is an AlN thin film, is epitaxially grown on a sapphire substrate. The buffer layer is used to alleviate the lattice mismatch between the epitaxial layer and the substrate, so as to facilitate the growth of subsequent epitaxial layers and improve the crystal quality of the subsequent epitaxial layers.

[0059] Specifically, an AlN thin film with a thickness of 10-20 nm is grown on a sapphire substrate using PVD sputtering as a buffer layer.

[0060] In addition, an undoped GaN layer is epitaxially grown on the AlN buffer layer. The presence of an undoped GaN layer on the AlN buffer layer improves the crystal quality of the epitaxial growth of the undoped GaN layer, reduces through-dislocations caused by the poor crystal quality of the AlN buffer layer, and improves the performance of the LED epitaxial wafer.

[0061] Specifically, the temperature is heated to between 1000-1200℃ and the pressure is adjusted to between 150-200 Torr, and an undoped GaN layer with a thickness of 2-3 μm is epitaxially grown on the AlN buffer layer.

[0062] Step S12: A defect barrier layer is epitaxially grown on the undoped GaN layer, wherein the defect barrier layer sequentially comprises a first defect barrier layer, a second defect barrier layer, and a third defect barrier layer, and the first defect barrier layer is Al. a Ga 1-a The first defect barrier layer is an N-type thin film layer, the second defect barrier layer is a BN-type thin film layer, and the third defect barrier layer is an Al-type thin film layer. a Ga 1-a N thin film layer;

[0063] In this process, a defect barrier layer is epitaxially grown on an undoped GaN layer. This defect barrier layer includes a first defect barrier layer, a second defect barrier layer, and a third defect barrier layer. The first defect barrier layer is Al. a Ga 1-a The first defect barrier layer is an N-type thin film, the second defect barrier layer is a BN-type thin film, and the third defect barrier layer is an Al-type thin film. a Ga 1-a N thin film layer. The first and third defect blocking layers have the same material, thickness, and Al composition ratio, which reduces lattice mismatch between the epitaxial layer and the substrate. Because the radius of an Al atom is smaller than that of a Ga atom, the surface diffusion length of Al atoms is shorter, leading to parasitic reactions during epitaxial growth and reducing Al content. a Ga 1-a The crystal quality of the N thin film layer is important, while the Al composition ratio (a) of the first and third defect barrier layers is 0.005-0.1, which is relatively low and can effectively prevent Al from entering the thin film. a Ga 1-aParasitic reactions during the epitaxial growth of N thin film layers improve the crystal quality of the first and second defect blocking layers.

[0064] It should be noted that the thickness of the defect blocking layer is 10-50nm. In order to reduce the lattice matching degree between the defect blocking layer and the undoped GaN layer and the N-type GaN layer, the thickness ratio of the first defect blocking layer, the second defect blocking layer and the third defect blocking layer is 1:1:1 to 1:10:1. The thickness ratio and design of the three-layer defect blocking layer can effectively adapt to the lattice constant of the undoped GaN layer and the N-type GaN layer, and improve the crystal quality of the LED epitaxial wafer.

[0065] First, a first defect barrier layer, which is Al, is epitaxially grown on the undoped GaN layer. a Ga 1-a The N thin film layer can effectively mitigate the lattice mismatch with the undoped GaN layer, while preventing dislocations and defects caused by the substrate, buffer layer and undoped GaN from extending and expanding toward the growth direction of the subsequent epitaxial layer.

[0066] Specifically, the temperature was adjusted to between 950-1150℃ and the pressure to between 100-400 Torr, and Al was epitaxially grown on the undoped GaN layer. a Ga 1-a The N-film layer serves as the first defect barrier layer, allowing for the epitaxial growth of Al at higher temperatures and lower pressures. a Ga 1-a The N thin film layer helps to increase the surface diffusion length of Al atoms, further reduce the parasitic reactions of Al atoms, and improve the crystal quality of the first defect barrier layer.

[0067] Secondly, a second defect-blocking layer, a BN thin film, is epitaxially grown on the first defect-blocking layer. Since the radius of a B atom is smaller than that of an Al atom, and the density and crystal quality of the BN thin film are superior to those of Al, this method is suitable for applications where the radius of a B atom is smaller than that of an Al atom. a Ga 1-a The N-film layer and the BN-film layer can effectively fill the dislocation and defect positions that cannot be blocked in the first defect blocking layer, further suppress the extension of dislocations and defects to the subsequent epitaxial layer, improve the crystal quality of the subsequent epitaxial layer, and thus improve the luminous efficiency and photoelectric performance of the LED epitaxial wafer.

[0068] Specifically, the temperature is adjusted to between 950-1150℃ and the pressure is adjusted to between 100-400 Torr, and a BN thin film layer is epitaxially grown on the first defect barrier layer as a second defect barrier layer.

[0069] Finally, a third defect barrier layer, which is Al, is epitaxially grown on the second defect barrier layer. a Ga 1-aThe N-type thin film layer mitigates the lattice mismatch between the second defect barrier layer and the N-type GaN layer, i.e., it mitigates the lattice mismatch between the BN thin film layer and the N-type GaN layer, reduces dislocations and defects caused by lattice mismatch, improves the crystal quality of the N-type GaN layer, and thus improves the crystal quality of the LED epitaxial wafer.

[0070] Specifically, the temperature is adjusted to between 950-1150℃ and the pressure to between 100-400 Torr, and Al is epitaxially grown on the second defect barrier layer. a Ga 1-a The N-film layer serves as the third defect barrier layer.

[0071] Step S13: An N-type GaN layer, a light-emitting layer, an electron-blocking layer, a P-type GaN layer, and a contact layer are epitaxially grown sequentially on the defect blocking layer.

[0072] In this process, an N-type GaN layer is epitaxially grown on the defect blocking layer. This N-type GaN layer possesses excess electrons, which are then provided to the light-emitting layer, enabling radiative recombination of electrons and holes for luminescence. Epitaxial growth of the N-type GaN layer on the defect blocking layer blocks dislocations and defects caused by lattice mismatch, effectively suppressing the extension of dislocations and defects into the N-type GaN layer, improving the crystal quality of the N-type GaN layer, thereby enhancing the effective radiative recombination of the light-emitting layer and improving the luminous efficiency and photoelectric performance of the LED epitaxial wafer.

[0073] Specifically, the temperature is heated to between 950-1150℃ and the pressure is adjusted to between 100-600 Torr to epitaxially grow an N-type GaN layer with a thickness of 2-3 μm on the defect barrier layer. The dopant of the N-type GaN layer is silicon (Si), and the doping concentration is 1.6E19cm. -3 -5E19cm -3 between.

[0074] In addition, an emissive layer is epitaxially grown on an N-type GaN layer. The N-type GaN layer provides electrons to the emissive layer, and the P-type GaN layer provides holes to the emissive layer, enabling radiative recombination of electrons and holes on the emissive layer. This emissive layer has a multi-quantum-well structure, comprising several periodically alternating quantum well layers and quantum barrier layers, with a stacking period of 6-12. The quantum well layers are InGaN quantum well layers, with a growth temperature between 790-810℃ and a thickness of 2-3.5 nm for each individual InGaN quantum well layer. The quantum barrier layers are Al... b Ga 1-b The N quantum barrier layer, with a growth temperature between 850-900℃, contains a single Al b Ga 1-b The thickness of the N quantum barrier layer is 9-12 nm, in which the Al component accounts for 0.05-0.2%.

[0075] In this process, an electron blocking layer 700 is epitaxially grown on an N-type GaN layer. Since the electron migration rate is greater than the hole migration rate, electrons migrate to the P-type GaN layer, where non-radiative recombination occurs, reducing the luminous efficiency of the LED epitaxial wafer. The electron blocking layer 700 can block electrons from migrating from the N-type GaN layer to the P-type GaN layer, confining them to the luminescent layer region. This enhances the effective radiative recombination of electrons and holes in the multiple quantum well layers of the luminescent layer, thereby improving the luminous efficiency of the LED epitaxial wafer. This electron blocking layer 700 is an Al layer with a thickness of 10-40 nm. c In d Ga 1-c-d The N thin film layer is grown at a temperature between 900-1000℃, wherein the component proportion of Al is c 0.05-0.1 and the component proportion of In is d 0.05-0.2.

[0076] In Al c In d Ga 1-c-d A P-type GaN layer is epitaxially grown on the N-type electron blocking layer 700. The P-type GaN layer has excess holes, which provide holes to the light-emitting layer to achieve radiative recombination of electrons and holes in the multiple quantum wells of the light-emitting layer.

[0077] Specifically, the temperature is adjusted to between 900-1000℃, and the pressure is adjusted to between 100-600 Torr, in Al c In d Ga 1-c-d A p-type doped GaN layer is epitaxially grown on the N-electron blocking layer 700. The dopant in the p-type doped GaN layer is magnesium (Mg), and its doping concentration is 1E19cm⁻¹. -3 -1E20cm -3 between.

[0078] Naturally, a contact layer is epitaxially grown on the P-type GaN layer, which is used to form an ohmic contact with the electrode, effectively reducing voltage and improving brightness.

[0079] Specifically, the temperature is heated to between 850-950℃ and the pressure is adjusted to between 100-400 Torr to epitaxially grow a contact layer with a thickness of 5-20 nm on a p-type GaN layer. The dopant of the contact layer is magnesium (Mg), and its doping concentration is 1E21cm. -3 -5E21cm -3 between.

[0080] It should be noted that when an external electric field is applied to both ends of the epitaxial wafer of a light-emitting diode (LED), with the N-type GaN layer as the negative electrode and the P-type GaN layer as the positive electrode, the N-type GaN layer has excess electrons and the P-type GaN layer has excess holes. Electrons in the N-type GaN layer migrate towards the positive P-type GaN layer, and holes in the P-type GaN layer migrate towards the negative N-type GaN layer. The electrons and holes that migrate from both ends meet in the light-emitting layer, that is, electron-hole radiative recombination occurs in the multiple quantum wells, thereby realizing the light emission of the LED epitaxial wafer.

[0081] Compared to existing technologies, the method for fabricating a light-emitting diode epitaxial wafer provided in this embodiment has the following advantages: By epitaxially growing a three-layer defect-blocking layer, the dislocation and defect density of the light-emitting diode epitaxial wafer is reduced, improving the crystal quality of the epitaxial wafer and enhancing the luminous efficiency and photoelectric performance of the light-emitting diode. Specifically, the defect-blocking layer includes a first defect-blocking layer, a second defect-blocking layer, and a third defect-blocking layer. The first and second defect-blocking layers block dislocations and defects formed by lattice mismatch from oriented towards the epitaxial layer growth direction. The extension and expansion effectively suppress the extension of dislocations and defects to the light-emitting layer, improve the radiative recombination of the light-emitting layer, and enhance the luminous efficiency of the LED epitaxial wafer. The third defect blocking layer reduces the lattice mismatch between the second defect blocking layer and the N-type GaN layer, improves the crystal quality of the N-type GaN layer, thereby improving the crystal quality of the LED epitaxial wafer, reducing dislocation and defect density, and improving the luminous efficiency and photoelectric performance of the LED epitaxial wafer. This solves the technical problem that the large lattice mismatch between the substrate and the epitaxial layer leads to an increase in the dislocation density of the epitaxial layer, which affects the luminous efficiency and photoelectric performance of the LED epitaxial wafer.

[0082] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively 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 all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A light-emitting diode epitaxial wafer, characterized in that, The light-emitting diode epitaxial wafer includes: Substrate; A buffer layer, an undoped GaN layer, a defect blocking layer, an N-type GaN layer, a light-emitting layer, an electron blocking layer, a P-type GaN layer, and a contact layer are sequentially disposed on the substrate. The defect barrier layer comprises, in sequence, a first defect barrier layer, a second defect barrier layer, and a third defect barrier layer, wherein the first defect barrier layer is Al. a Ga 1-a The first defect barrier layer is an N-type thin film layer, the second defect barrier layer is a BN-type thin film layer, and the third defect barrier layer is an Al-type thin film layer. a Ga 1-a The N thin film layer has the same Al component concentration in the first defect blocking layer and the third defect blocking layer, with an Al component ratio a of 0.005-0.

1. The thickness of the defect blocking layer is 10-50 nm, and the thickness ratio of the first defect blocking layer, the second defect blocking layer and the third defect blocking layer is 1:1:1 to 1:10:

1.

2. The light-emitting diode epitaxial wafer according to claim 1, characterized in that, The buffer layer is an AlN thin film with a thickness of 10-20 nm.

3. The light-emitting diode epitaxial wafer according to claim 1, characterized in that, The light-emitting layer has a multi-quantum-well structure, including several periods of InGaN quantum well layers and Al. b Ga 1-b N-quantum barrier layer.

4. The light-emitting diode epitaxial wafer according to claim 3, characterized in that, The thickness of the InGaN quantum well layer is 2-3.5 nm, and the Al b Ga 1-b The thickness of the N quantum barrier layer is 9-12 nm, in which the Al component accounts for 0.05-0.2%.

5. The light-emitting diode epitaxial wafer according to claim 1, characterized in that, The electron blocking layer is Al. c In d Ga 1-c-d The N thin film layer has a thickness of 10-40 nm, in which the Al component accounts for 0.005-0.1% (c) and the In component accounts for 0.05-0.2% (d).

6. The light-emitting diode epitaxial wafer according to claim 1, characterized in that, The contact layer is a MgGaN thin film with a thickness of 5-20 nm, and the dopant in the contact layer is magnesium with a doping concentration of 1E21cm⁻¹. -3 -5E21 cm -3 between.

7. A method for fabricating a light-emitting diode epitaxial wafer, characterized in that, The preparation method is used to prepare the light-emitting diode epitaxial wafer according to claims 1 to 6, and the preparation method includes: Provide a substrate; A buffer layer and an undoped GaN layer are sequentially grown on the substrate; A defect barrier layer is epitaxially grown on the undoped GaN layer, wherein the defect barrier layer sequentially comprises a first defect barrier layer, a second defect barrier layer, and a third defect barrier layer, wherein the first defect barrier layer is Al. a Ga 1-a The first defect barrier layer is an N-type thin film layer, the second defect barrier layer is a BN-type thin film layer, and the third defect barrier layer is an Al-type thin film layer. a Ga 1-a N thin film layer, the first defect blocking layer and the third defect blocking layer have the same Al component concentration, the Al component ratio a is 0.005-0.1, the thickness of the defect blocking layer is 10-50nm, and the thickness ratio of the first defect blocking layer, the second defect blocking layer and the third defect blocking layer is 1:1:1-1:10:1; An N-type GaN layer, a light-emitting layer, an electron-blocking layer, a P-type GaN layer, and a contact layer are sequentially epitaxially grown on the defect blocking layer.

8. The method for fabricating a light-emitting diode epitaxial wafer according to claim 7, characterized in that, The growth steps of the defect barrier layer include: The temperature is heated to between 950-1150℃ and the pressure is adjusted to between 100-400 Torr, and the first defect barrier layer, the second defect barrier layer and the third defect barrier layer are epitaxially grown sequentially. Wherein, the first defect barrier layer is Al a Ga 1-a The first defect barrier layer is an N-type thin film layer, the second defect barrier layer is a BN-type thin film layer, and the third defect barrier layer is an Al-type thin film layer. a Ga 1-a N thin film layer.

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