Light emitting diode epitaxial wafer and preparation method thereof, and light emitting diode

Abstract

The application discloses a light emitting diode epitaxial wafer and a preparation method thereof and a light emitting diode, and relates to the field of semiconductor photoelectric devices. The light emitting diode epitaxial wafer comprises a substrate and a buffer layer, a non-doped GaN layer, an N-type GaN layer, a multi-quantum well layer, an intercalation layer, an electron blocking layer and a P-type GaN layer arranged on the substrate in sequence; the intercalation layer comprises an AlN layer and a superlattice layer; the superlattice layer comprises P-AlN layers, P-InN layers and P-GaN layers which are stacked in sequence, and the number of periods is greater than or equal to 2. By implementing the application, the light emitting efficiency of the light emitting diode can be improved.

Description

LED epitaxial wafers and their fabrication methods, LEDs Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic devices, and more particularly to a light-emitting diode epitaxial wafer and its fabrication method, and a light-emitting diode. Background Technology

[0002] Obtaining p-type GaN is significantly more difficult than obtaining n-type GaN, severely hindering the development of GaN materials and devices. Although breakthroughs have been made in p-type doping of GaN, challenges remain, including low activation rates of p-type impurities and difficulty in achieving high hole concentrations (>10⁻⁶). 19 cm -3 This is mainly due to the low solubility of Mg in GaN. When the doping concentration reaches a certain level, further increases in the Mg impurity concentration will cause Mg to form Mg-N complexes instead of entering the GaN lattice, exhibiting donor characteristics and producing a severe self-compensation effect, which greatly reduces the concentration of activated Mg. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an epitaxial wafer for a light-emitting diode and a method for preparing the same, which can improve the luminous efficiency of the light-emitting diode.

[0004] Another technical problem that this invention aims to solve is to provide a light-emitting diode with high luminous efficiency.

[0005] To address the above problems, this invention discloses a light-emitting diode epitaxial wafer, which includes a substrate and a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an insertion layer, an electron blocking layer, and a P-type GaN layer sequentially disposed on the substrate.

[0006] The insertion layer includes an AlN layer and a superlattice layer stacked sequentially on the multi-quantum-well layer. The superlattice layer includes a P-AlN layer, a P-InN layer and a P-GaN layer stacked sequentially, with a period number ≥ 2.

[0007] As an improvement to the above technical solution, the thickness of the AlN layer is 1-10 nm, and the thickness of the superlattice layer is 1-20 nm.

[0008] As an improvement to the above technical solution, in the superlattice layer, the thickness ratio of the P-AlN layer, P-InN layer and P-GaN layer is 1:(1~5):(1~5).

[0009] As an improvement to the above technical solution, the doping concentration of the P-AlN layer is 1×10⁻⁶. 18 ~1×10 21 cm -3The doping concentration of the P-InN layer is 1×10⁻⁶. 18 ~1×10 21 cm -3 The doping concentration of the P-GaN layer is 1×10⁻⁶. 18 ~1×10 21 cm -3 .

[0010] As an improvement to the above technical solution, the number of periods of the superlattice layer is 3 to 10.

[0011] Accordingly, the present invention also discloses a method for fabricating a light-emitting diode (LED), used to fabricate the aforementioned LED epitaxial wafer, comprising:

[0012] A substrate is provided on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an insertion layer, an electron blocking layer and a P-type GaN layer are sequentially grown.

[0013] The insertion layer includes an AlN layer and a superlattice layer stacked sequentially on the multi-quantum-well layer. The superlattice layer includes a P-AlN layer, a P-InN layer and a P-GaN layer stacked sequentially, with a period number ≥ 2.

[0014] As an improvement to the above technical solution, the growth temperature of the AlN layer is 800-900℃, and the growth pressure is 50-300 torr;

[0015] The growth temperature of the superlattice layer is 700–800℃, and the growth pressure is 50–300 torr.

[0016] As an improvement to the above technical solution, the growth temperature of the P-GaN layer in the superlattice layer is higher than that of the P-AlN layer and the P-InN layer.

[0017] As an improvement to the above technical solution, the growth atmosphere of the AlN layer is a mixture of N2 and NH3, and the volume ratio of N2 to NH3 is (0.5~2):1.

[0018] The growth atmosphere of the superlattice layer is a mixture of N2, H2 and NH3, and the volume ratio of N2, H2 and NH3 is 1:(10~20):(5~10).

[0019] Accordingly, the present invention also discloses a light-emitting diode, which includes the above-mentioned light-emitting diode epitaxial wafer.

[0020] Implementing this invention has the following beneficial effects:

[0021] 1. The light-emitting diode epitaxial wafer of the present invention has an insertion layer between a multi-quantum-well layer and an electron blocking layer. This insertion layer includes an AlN layer and a superlattice layer. The superlattice layer comprises multiple sequentially stacked P-AlN layers, P-InN layers, and P-GaN layers. The AlN layer reduces electron overflow into the superlattice layer and reduces non-radiative recombination between electrons and holes. The large bandgap of the P-AlN layer in the superlattice layer forms a barrier layer, further blocking electron overflow. The relatively low bandgap of the P-InN layer forms a potential well layer, temporarily storing generated holes. Furthermore, the introduction of In into the P-InN layer lowers the activation energy of Mg, increases the concentration of activated Mg, and increases the number of generated holes. The P-GaN layer in the superlattice layer provides a large number of holes. The superlattice layer composed of these three elements ensures uniform hole injection into the multi-quantum-well layer, improves electron-hole recombination efficiency, and enhances luminous efficiency.

[0022] 2. In the light-emitting diode of the present invention, the growth temperature of the superlattice layer is relatively low, which can increase the Mg doping concentration. Simultaneously, by controlling the growth atmosphere to be a mixed gas of N2, NH3, and H2, Mg-H composites are formed at low temperatures, further increasing the Mg doping concentration. Furthermore, by increasing the growth temperature of the P-GaN layer, the Mg-H activation doping of Mg can be interrupted, thereby increasing the Mg doping concentration. Attached Figure Description

[0023] Figure 1 is a schematic diagram of the structure of a light-emitting diode epitaxial wafer in one embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of the structure of the insertion layer in one embodiment of the present invention;

[0025] Figure 3 is a flowchart of a method for fabricating an epitaxial wafer of a light-emitting diode according to an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0027] Referring to Figures 1 and 2, this invention discloses a light-emitting diode epitaxial wafer, comprising a substrate 1 and a buffer layer 2, an undoped GaN layer 3, an N-type GaN layer 4, a multiple quantum well layer 5, an insertion layer 6, an electron blocking layer 7, and a P-type GaN layer 8 sequentially disposed on the substrate 1. The insertion layer 6 comprises an AlN layer 61 and a superlattice layer 62 sequentially stacked on the multiple quantum well layer 5. The superlattice layer 62 comprises multiple sequentially stacked P-AlN layers 621, P-InN layers 622, and P-GaN layers 623, with a period number ≥ 2. Based on this structure, the AlN layer 61 reduces electron overflow to the superlattice layer and reduces nonradiative recombination of electrons and holes. The large bandgap of the P-AlN layer 621 in the superlattice layer 62 forms a barrier layer, further blocking electron overflow. Simultaneously, because the P-AlN layer 621 is doped with Mg, it increases the number of holes generated. The P-InN layer 622 in the superlattice layer 62 has a low bandgap, forming a potential well layer to temporarily store holes. Furthermore, the introduction of In into the P-InN layer 622 lowers the activation energy of Mg, increases the concentration of activated Mg, and further increases the number of holes generated. The P-GaN layer 623 in the superlattice layer 62 provides a greater number of holes. The superlattice layer composed of these three elements ensures uniform hole injection into the multi-quantum-well layer, improving electron-hole recombination efficiency and thus enhancing luminescence efficiency.

[0028] The AlN layer 61 has a thickness of 0.5–15 nm. When its thickness is less than 0.5 nm, it is difficult to effectively block electron overflow; when its thickness is greater than 15 nm, the efficiency of hole injection into the multi-quantum well layer 5 decreases, thus reducing the luminous efficiency. For example, the thickness of the AlN layer 61 can be 0.8 nm, 1.4 nm, 3 nm, 4.5 nm, 6 nm, 10 nm, 11 nm, 12.4 nm, or 13 nm, but is not limited to these. Preferably, it is 1–10 nm.

[0029] The thickness of the superlattice layer 62 is 0.5–30 nm, and exemplary examples are 1.5 nm, 5 nm, 12 nm, 18 nm, 20 nm, 24 nm, or 28 nm, but it is not limited thereto. Preferably, the thickness of the superlattice layer 62 is 1–20 nm.

[0030] Specifically, the thickness ratio of the P-AlN layer 621, P-InN layer 622, and P-GaN layer 623 in the superlattice layer 62 is (1-2):(1-5):(1-5). By controlling the thickness ratio of these three layers, the overall crystal quality of the superlattice layer 62 can be guaranteed; the concentration of activated Mg can be effectively increased, thereby enhancing the radiative recombination of holes and electrons and improving luminescence efficiency. For example, the thickness ratio of the P-AlN layer 621, P-InN layer 622, and P-GaN layer 623 in the superlattice layer 62 is 1:2:3, 2:1:1.5, 1.5:3:4, 1.8:3:2, or 1:3:4, but is not limited to these. Preferably, the thickness ratio of the P-AlN layer 621, P-InN layer 622, and P-GaN layer 623 is 1:(1-5):(1-5).

[0031] Specifically, the p-type dopant element of the P-AlN layer 621 in the superlattice layer 62 is Mg or Be, but is not limited to these. Mg is preferred, and its doping concentration is 1 × 10⁻⁶. 18 ~1×10 21 cm -3 By introducing a p-type doped AlN layer, residual electrons can be blocked while holes can be provided, increasing the number of holes. Preferably, the doping concentration of the p-AlN layer 621 is 1×10⁻⁶. 18 ~3×10 19 cm -3 Furthermore, its doping concentration is lower than that of the P-InN layer 622 and the P-GaN layer 623. Based on this configuration, the P-AlN layer 621 can also accelerate holes, thereby improving the efficiency of hole injection into the multi-quantum-well layer 5.

[0032] Specifically, the p-type dopant element of the P-InN layer 622 in the superlattice layer 62 is Mg or Be, but is not limited to these. Mg is preferred, and its doping concentration is 1 × 10⁻⁶. 18 ~1×10 21 cm -3 In the p-type InN layer 63, In is introduced, which can further increase the Mg doping concentration. Preferably, the doping concentration of the p-type InN layer 63 is 5 × 10⁻⁶. 19 ~5×10 20 cm -3 .

[0033] Specifically, the p-type dopant element of the P-GaN layer 623 in the superlattice layer 62 is Mg or Be, but is not limited to these. Mg is preferred, and its doping concentration is 1 × 10⁻⁶. 18 ~1×10 21 cm -3 The preferred size is 8×10. 19 ~1×10 21 cm -3 .

[0034] The superlattice layer 62 has 2 to 15 periods. By controlling the number of periods, the uniformity of the hole injection quantum well can be improved, thereby increasing the uniformity of light emission. For example, the number of periods of the superlattice layer 62 is 3, 4, 5, 7, 9, 11, or 14, but is not limited to these. Preferably, the number of periods of the superlattice layer 62 is 3 to 10.

[0035] The substrate 1 may be a sapphire substrate, a SiO2-sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, or a zinc oxide substrate, but is not limited to these.

[0036] The buffer layer 2 can be an AlN layer and / or an AlGaN layer, but is not limited thereto. The thickness of the buffer layer 2 is 10–50 nm, exemplarily 13 nm, 17 nm, 21 nm, 36 nm, 39 nm, 43 nm, or 48 nm, but is not limited thereto. The buffer layer 2 provides nucleation centers with the same orientation as the substrate 1, releasing the stress caused by the lattice mismatch between GaN and the substrate 1, as well as the thermal stress caused by the mismatch in the coefficient of thermal expansion. Further growth provides a flat nucleation surface, reducing the contact angle of its nucleation growth, allowing the island-shaped GaN grains to connect into a surface within a smaller thickness, transforming into two-dimensional epitaxial growth.

[0037] The thickness of the undoped GaN layer 3 is 1–5 μm, with exemplary thicknesses of 1.2 μm, 1.6 μm, 2.2 μm, 2.8 μm, 3.5 μm, 4.2 μm, or 4.7 μm, but not limited to these. The undoped GaN layer exhibits superior crystal quality. As the GaN thickness increases, compressive stress is released through stacking faults, line defects are reduced, crystal quality is improved, and reverse leakage current is decreased.

[0038] The N-type GaN layer 4 is doped with Si, but is not limited to Si. The doping concentration of the N-type GaN layer 4 is 1×10⁻⁶. 19 ~5×10 19 cm -3 The thickness is 2-3 μm.

[0039] Among them, the multi-quantum well layer 5 consists of alternating stacked InGaN well layers and AlGaN barrier layers, with a stacking period of 6–12. The thickness of a single InGaN well layer is 2–5 nm. The thickness of a single AlGaN barrier layer is 5–15 nm.

[0040] Among them, electron blocking layer 7 is Al α In βThe GaN layer has an α value of 0.005–0.1 and a β value of 0.01–0.2. The electron blocking layer 7 has a thickness of 10–40 nm. This electron blocking layer 7 can effectively limit electron overflow and reduce the blocking of holes, thereby improving the injection efficiency of holes into the quantum well, reducing carrier Auger recombination, and improving the luminous efficiency of the light-emitting diode.

[0041] The doping element in the p-type GaN layer 8 is Mg or Be, but is not limited to these. Mg is preferred. The doping concentration of the p-type GaN layer 8 is 2 × 10⁸. 19 ~1×10 21 cm -3 The thickness of the p-type GaN layer 8 is 10–50 nm.

[0042] Accordingly, referring to Figure 3, the present invention also discloses a method for preparing a light-emitting diode epitaxial wafer, which is used to prepare the above-mentioned light-emitting diode epitaxial wafer, and includes the following steps:

[0043] S1: Provides a substrate;

[0044] S2: Grow a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an insertion layer, an electron blocking layer, and a P-type GaN layer on the substrate;

[0045] Specifically, S2 includes:

[0046] S21: Grow a buffer layer on the substrate;

[0047] Specifically, an AlGaN layer grown by MOCVD or an AlN layer grown by PVD can be used as a buffer layer, but this is not the only option. Preferably, an AlN layer grown by PVD is used as a buffer layer. After growth, the substrate is loaded into an MOCVD chamber and pretreated for 1–10 min in an H2 atmosphere at 1000–1200 °C and valence adjusted by 100–300 torr, followed by nitriding treatment.

[0048] S22: Growing an undoped GaN layer on the buffer layer;

[0049] Specifically, in one embodiment of the present invention, an undoped GaN layer is grown in MOCVD at a growth temperature of 1050–1200°C and a growth pressure of 50–500 torr.

[0050] S23: Growing an N-type GaN layer on an undoped GaN layer;

[0051] Specifically, in one embodiment of the present invention, an N-type GaN layer is grown in MOCVD at a growth temperature of 1050–1200°C and a growth pressure of 50–500 torr.

[0052] S24: Growth of multiple quantum well layers on N-type GaN layers;

[0053] Specifically, in one embodiment of the present invention, InGaN well layers and AlGaN barrier layers are periodically grown in MOCVD to form a multi-quantum-well layer. The growth temperature of the InGaN well layer is 790–810°C, and the growth pressure is 50–300 torr. The growth temperature of the AlGaN barrier layer is 800–900°C, and the growth pressure is 50–300 torr.

[0054] S25: Growing an insertion layer on a multi-quantum-well layer;

[0055] Specifically, S25 includes:

[0056] S251: Growing AlN layers on multi-quantum-well layers;

[0057] Specifically, an AlGaN layer can be grown using MOCVD or PVD as a buffer layer, but is not limited to these methods. Preferably, in one embodiment of the present invention, the AlN layer is grown using MOCVD at a growth temperature of 800–900°C and a growth pressure of 50–300 torr. The AlN layer grown under these conditions has high crystal quality and can effectively block electrons.

[0058] More preferably, in one embodiment of the present invention, the growth atmosphere of the AlN layer is a mixture of N2 and NH3, and the volume ratio of N2 to NH3 is (0.5 to 2):1, exemplarily 0.7:1, 1:1, 1.2:1, 1.5:1 or 1.8:1, but not limited thereto. By controlling the growth atmosphere of the AlN layer, the crystal quality of the AlN layer can be further improved.

[0059] S252: A superlattice layer is grown on an AlN layer;

[0060] Specifically, in one embodiment of the present invention, P-AlN, P-InN, and P-GaN layers are periodically grown using MOCVD. The growth temperature for all three is 700–800°C, and the growth pressure is 50–300 torr. Using a lower growth temperature can increase the Mg doping concentration. Preferably, in one embodiment of the present invention, the growth temperature of the P-GaN layer 623 in the superlattice layer 62 is higher than that of the P-AlN layer 621 and the P-InN layer 622, in order to anneal the Mg-H bonds formed during the early growth process, thereby breaking the Mg-H bonds and activating the doped Mg.

[0061] Preferably, in one embodiment of the present invention, the growth atmosphere of the superlattice layer is a mixture of N2, H2 and NH3, and the volume ratio of N2, H2 and NH3 is 1:(10-20):(5-10). Introducing H2 can form Mg-H bonds, and the bonding energy of Mg-H at low temperatures is much lower than that of Mg-N. Therefore, introducing H2 during low-temperature growth can increase the doping concentration of Mg.

[0062] S26: An electron blocking layer is grown on the insertion layer;

[0063] Specifically, in one embodiment of the present invention, an electron blocking layer is grown in MOCVD. The growth temperature is 900–1000°C, and the growth pressure is 100–300 torr.

[0064] S27: Grow a P-type GaN layer on an electron blocking layer;

[0065] Specifically, in one embodiment of the present invention, a P-type GaN layer is grown in MOCVD at a growth temperature of 900–1100°C and a growth pressure of 100–600 torr.

[0066] The present invention will be further described below with reference to specific embodiments:

[0067] Example 1

[0068] This embodiment provides a light-emitting diode epitaxial wafer, referring to Figures 1 and 2, which includes a substrate 1 and a buffer layer 2, an undoped GaN layer 3, an N-type GaN layer 4, a multiple quantum well layer 5, an insertion layer 6, an electron blocking layer 7, and a P-type GaN layer 8 sequentially disposed on the substrate 1.

[0069] In this design, substrate 1 is a sapphire substrate; buffer layer 2 is an AlN layer with a thickness of 15 nm; undoped GaN layer 3 has a thickness of 2.2 μm; and the Si doping concentration in N-type GaN layer 4 is 2.5 × 10⁻⁶. 19 cm -3 Its thickness is 2.5μm.

[0070] Among them, the multi-quantum well layer 5 is a periodic structure formed by alternating stacked InGaN well layers and AlGaN barrier layers, with a stacking period of 10, a thickness of 3.5 nm for a single InGaN well layer, and a thickness of 9.8 nm for a single AlGaN barrier layer.

[0071] The insertion layer 6 comprises sequentially stacked AlN layers 61 and a superlattice layer 62. The superlattice layer 62 includes multiple sequentially stacked P-AlN layers 621, P-InN layers 622, and P-GaN layers 623, with a period number of 8. The AlN layer 61 has a thickness of 2 nm, the superlattice layer 62 has a thickness of 5 nm, and the thickness ratio of the P-AlN layers 621, P-InN layers 622, and P-GaN layers 623 is 1:1:1. The dopant element in the P-AlN layers 621, P-InN layers 622, and P-GaN layers 623 is Mg, with a doping concentration of 5 × 10⁻⁶. 18 cm -3 .

[0072] Among them, electron blocking layer 7 is Al α In β The GaN layer (α = 0.04, β = 0.01) has a thickness of 15 nm. The p-type GaN layer 8 is doped with Mg at a doping concentration of 2 × 10⁸. 20 cm -3 The thickness is 15nm.

[0073] The method for fabricating the epitaxial wafer of the light-emitting diode in this embodiment includes the following steps:

[0074] (1) Provide a substrate;

[0075] (2) Grow a buffer layer on the substrate;

[0076] Specifically, an AlN layer is grown by PVD, then the substrate is loaded into MOCVD, annealed at 1150℃, 200 torr, and H2 atmosphere for 6 min, and then nitrided.

[0077] (3) Grow an undoped GaN layer on the buffer layer;

[0078] Specifically, an undoped GaN layer was grown in MOCVD at a growth temperature of 1100℃ and a growth pressure of 150 torr.

[0079] (4) An N-type GaN layer is grown on an undoped GaN layer;

[0080] Specifically, an N-type GaN layer was grown in MOCVD at a temperature of 1120℃ and a growth pressure of 100 torr.

[0081] (5) Growth of multiple quantum well layers on N-type GaN layers;

[0082] Specifically, InGaN well layers and AlGaN barrier layers are periodically grown in MOCVD to form a multi-quantum-well layer. The InGaN well layer is grown at a temperature of 795℃ and a growth pressure of 200 torr. The AlGaN barrier layer is grown at a temperature of 855℃ and a growth pressure of 200 torr.

[0083] (6) Growing AlN layers on multi-quantum-well layers;

[0084] Specifically, the AlN layer was grown using MOCVD at a growth temperature of 840℃ and a growth pressure of 100 torr. The growth atmosphere was a mixture of N2 and NH3 with a volume ratio of 1.5:1.

[0085] (7) Growth of a superlattice layer on an AlN layer;

[0086] Specifically, P-AlN, P-InN, and P-GaN layers were periodically grown using MOCVD. The growth temperature for all three was 760℃, and the growth pressure was 150 torr. The growth atmosphere for all three was a mixture of N2 and NH3, with a volume ratio of N2 to NH3 of 1.5:1.

[0087] (8) Grow an electron blocking layer on a superlattice layer;

[0088] Specifically, an electron blocking layer is grown in MOCVD. The growth temperature is 965℃ and the growth pressure is 200 torr.

[0089] (9) Grow a P-type GaN layer on the electron blocking layer;

[0090] Specifically, a p-type GaN layer was grown using MOCVD. The growth temperature was 985℃, and the growth pressure was 200 torr.

[0091] Example 2

[0092] This embodiment provides a light-emitting diode epitaxial wafer, referring to Figures 1 and 2, which includes a substrate 1 and a buffer layer 2, an undoped GaN layer 3, an N-type GaN layer 4, a multiple quantum well layer 5, an insertion layer 6, an electron blocking layer 7, and a P-type GaN layer 8 sequentially disposed on the substrate 1.

[0093] In this design, substrate 1 is a sapphire substrate; buffer layer 2 is an AlN layer with a thickness of 15 nm; undoped GaN layer 3 has a thickness of 2.2 μm; and the Si doping concentration in N-type GaN layer 4 is 2.5 × 10⁻⁶. 19 cm -3 Its thickness is 2.5μm.

[0094] Among them, the multi-quantum well layer 5 is a periodic structure formed by alternating stacked InGaN well layers and AlGaN barrier layers, with a stacking period of 10, a thickness of 3.5 nm for a single InGaN well layer, and a thickness of 9.8 nm for a single AlGaN barrier layer.

[0095] The insertion layer 6 comprises sequentially stacked AlN layers 61 and a superlattice layer 62. The superlattice layer 62 includes multiple sequentially stacked P-AlN layers 621, P-InN layers 622, and P-GaN layers 623, with a period number of 8. The AlN layer 61 has a thickness of 2 nm, the superlattice layer 62 has a thickness of 5 nm, and the thickness ratio of the P-AlN layers 621, P-InN layers 622, and P-GaN layers 623 is 1:2:3. The dopant element in the P-AlN layers 621, P-InN layers 622, and P-GaN layers 623 is Mg, with a doping concentration of 5 × 10⁻⁶. 18 cm -3 .

[0096] Among them, electron blocking layer 7 is Al α In β The GaN layer (α = 0.04, β = 0.01) has a thickness of 15 nm. The p-type GaN layer 8 is doped with Mg at a doping concentration of 2 × 10⁸. 20 cm -3 The thickness is 15nm.

[0097] The method for fabricating the epitaxial wafer of the light-emitting diode in this embodiment includes the following steps:

[0098] (1) Provide a substrate;

[0099] (2) Grow a buffer layer on the substrate;

[0100] Specifically, an AlN layer is grown by PVD, then the substrate is loaded into MOCVD, annealed at 1150℃, 200 torr, and H2 atmosphere for 6 min, and then nitrided.

[0101] (3) Grow an undoped GaN layer on the buffer layer;

[0102] Specifically, an undoped GaN layer was grown in MOCVD at a growth temperature of 1100℃ and a growth pressure of 150 torr.

[0103] (4) An N-type GaN layer is grown on an undoped GaN layer;

[0104] Specifically, an N-type GaN layer was grown in MOCVD at a temperature of 1120℃ and a growth pressure of 100 torr.

[0105] (5) Growth of multiple quantum well layers on N-type GaN layers;

[0106] Specifically, InGaN well layers and AlGaN barrier layers are periodically grown in MOCVD to form a multi-quantum-well layer. The InGaN well layer is grown at a temperature of 795℃ and a growth pressure of 200 torr. The AlGaN barrier layer is grown at a temperature of 855℃ and a growth pressure of 200 torr.

[0107] (6) Growing AlN layers on multi-quantum-well layers;

[0108] Specifically, the AlN layer was grown using MOCVD at a growth temperature of 840℃ and a growth pressure of 100 torr. The growth atmosphere was a mixture of N2 and NH3 with a volume ratio of 1.5:1.

[0109] (7) Growth of a superlattice layer on an AlN layer;

[0110] Specifically, P-AlN, P-InN, and P-GaN layers were periodically grown using MOCVD. The growth temperature for all three was 760℃, and the growth pressure was 150 torr. The growth atmosphere for all three was a mixture of N2 and NH3, with a volume ratio of N2 to NH3 of 1.5:1.

[0111] (8) Grow an electron blocking layer on a superlattice layer;

[0112] Specifically, an electron blocking layer is grown in MOCVD. The growth temperature is 965℃ and the growth pressure is 200 torr.

[0113] (9) Grow a P-type GaN layer on the electron blocking layer;

[0114] Specifically, a p-type GaN layer was grown using MOCVD. The growth temperature was 985℃, and the growth pressure was 200 torr.

[0115] Example 3

[0116] This embodiment provides a light-emitting diode epitaxial wafer, referring to Figures 1 and 2, which includes a substrate 1 and a buffer layer 2, an undoped GaN layer 3, an N-type GaN layer 4, a multiple quantum well layer 5, an insertion layer 6, an electron blocking layer 7, and a P-type GaN layer 8 sequentially disposed on the substrate 1.

[0117] In this design, substrate 1 is a sapphire substrate; buffer layer 2 is an AlN layer with a thickness of 15 nm; undoped GaN layer 3 has a thickness of 2.2 μm; and the Si doping concentration in N-type GaN layer 4 is 2.5 × 10⁻⁶. 19 cm -3 Its thickness is 2.5μm.

[0118] Among them, the multi-quantum well layer 5 is a periodic structure formed by alternating stacked InGaN well layers and AlGaN barrier layers, with a stacking period of 10, a thickness of 3.5 nm for a single InGaN well layer, and a thickness of 9.8 nm for a single AlGaN barrier layer.

[0119] The insertion layer 6 comprises sequentially stacked AlN layers 61 and a superlattice layer 62. The superlattice layer 62 comprises multiple sequentially stacked P-AlN layers 621, P-InN layers 622, and P-GaN layers 623, with a period number of 8. The AlN layer 61 has a thickness of 2 nm, the superlattice layer 62 has a thickness of 5 nm, and the thickness ratio of the P-AlN layers 621, P-InN layers 622, and P-GaN layers 623 is 1:2:3. The P-AlN layer 621 is doped with Mg at a concentration of 2.5 × 10⁻⁶. 18 cm -3 The P-InN layer 622 has a Mg doping concentration of 2.5 × 10⁻⁶. 19 cm -3 The doping concentration of the P-GaN layer 623 is Mg, with a doping concentration of 8 × 10⁻⁶. 20 cm -3 .

[0120] Among them, electron blocking layer 7 is Al α In β The GaN layer (α = 0.04, β = 0.01) has a thickness of 15 nm. The p-type GaN layer 8 is doped with Mg at a doping concentration of 2 × 10⁸. 20 cm -3 The thickness is 15nm.

[0121] The method for fabricating the epitaxial wafer of the light-emitting diode in this embodiment includes the following steps:

[0122] (1) Provide a substrate;

[0123] (2) Grow a buffer layer on the substrate;

[0124] Specifically, an AlN layer is grown by PVD, then the substrate is loaded into MOCVD, annealed at 1150℃, 200 torr, and H2 atmosphere for 6 min, and then nitrided.

[0125] (3) Grow an undoped GaN layer on the buffer layer;

[0126] Specifically, an undoped GaN layer was grown in MOCVD at a growth temperature of 1100℃ and a growth pressure of 150 torr.

[0127] (4) An N-type GaN layer is grown on an undoped GaN layer;

[0128] Specifically, an N-type GaN layer was grown in MOCVD at a temperature of 1120℃ and a growth pressure of 100 torr.

[0129] (5) Growth of multiple quantum well layers on N-type GaN layers;

[0130] Specifically, InGaN well layers and AlGaN barrier layers are periodically grown in MOCVD to form a multi-quantum-well layer. The InGaN well layer is grown at a temperature of 795℃ and a growth pressure of 200 torr. The AlGaN barrier layer is grown at a temperature of 855℃ and a growth pressure of 200 torr.

[0131] (6) Growing AlN layers on multi-quantum-well layers;

[0132] Specifically, the AlN layer was grown using MOCVD at a growth temperature of 840℃ and a growth pressure of 100 torr. The growth atmosphere was a mixture of N2 and NH3 with a volume ratio of 1.5:1.

[0133] (7) Growth of a superlattice layer on an AlN layer;

[0134] Specifically, P-AlN, P-InN, and P-GaN layers were periodically grown using MOCVD. The P-AlN layer was grown at 765℃ and 150 torr, using a mixture of N2, H2, and NH3 as the carrier gas, with a volume ratio of N2:12:6. The P-InN layer was grown at 765℃ and 150 torr, using the same mixture as the carrier gas. The P-GaN layer was grown at 785℃ and 150 torr, using the same mixture as the carrier gas.

[0135] (8) Grow an electron blocking layer on a superlattice layer;

[0136] Specifically, an electron blocking layer is grown in MOCVD. The growth temperature is 965℃ and the growth pressure is 200 torr.

[0137] (9) Grow a P-type GaN layer on the electron blocking layer;

[0138] Specifically, a p-type GaN layer was grown using MOCVD. The growth temperature was 985℃, and the growth pressure was 200 torr.

[0139] Comparative Example 1

[0140] The difference between this comparative example and Example 1 is that no insert layer is provided in the epitaxial wafer. Correspondingly, the preparation method does not include the step of preparing the insert layer. Everything else is the same as in Example 1.

[0141] Comparative Example 2

[0142] The difference between this comparative example and Example 1 is that the inserted layer only includes an AlN layer and does not include a superlattice layer. Correspondingly, the preparation method does not include the step of preparing the superlattice layer. Everything else is the same as in Example 1.

[0143] Comparative Example 3

[0144] The difference between this comparative example and Example 1 is that the inserted layer only includes a superlattice layer and does not include an AlN layer. Correspondingly, the preparation method does not include the step of preparing the AlN layer. Everything else is the same as in Example 1.

[0145] Brightness tests were performed on the LED epitaxial wafers obtained in Examples 1-3 and Comparative Examples 1-3. Based on the data of Comparative Example 1, the luminous efficacy improvement rate of other examples and comparative examples was calculated.

[0146] The specific results are as follows:

[0147] Luminous efficacy improvement rate: Example 1 1.2%; Example 2 1.6%; Example 3 2.5%; Comparative Example 1 -; Comparative Example 2 - 0.5%; Comparative Example 3 0.3%. surface

[0148] As can be seen from the table, the luminous efficacy is significantly improved after inserting the insert layer of the present invention into the epitaxial wafer structure. A comparison of Example 1 with Comparative Examples 2 and 3 shows that changing the insert layer structure of the present invention does not effectively improve the luminous efficacy.

[0149] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A light-emitting diode epitaxial wafer, characterized in that, The system includes a substrate and a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an insertion layer, an electron blocking layer, and a P-type GaN layer sequentially disposed on the substrate. The insertion layer includes an AlN layer and a superlattice layer. The superlattice layer comprises sequentially stacked P-AlN, P-InN, and P-GaN layers with a period number ≥ 2. In the superlattice layer, the thickness ratio of the P-AlN, P-InN, and P-GaN layers is 1:(1~5):(1~5). The thickness of the AlN layer is 1~10 nm, and the thickness of the superlattice layer is 1~20 nm. The doping concentration of the P-AlN layer is 1×10⁻⁶. 18 ~1×10 21 cm -3 The doping concentration of the P-InN layer is 1×10⁻⁶. 18 ~1×10 21 cm -3 The doping concentration of the P-GaN layer is 1×10⁻⁶. 18 ~1×10 21 cm -3 .

2. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The number of periods in the superlattice layer is 3 to 10.

3. A method for fabricating a light-emitting diode, used to fabricate a light-emitting diode epitaxial wafer as described in claim 1 or 2, characterized in that, include: A substrate is provided on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a multiple quantum well layer, an insertion layer, an electron blocking layer, and a P-type GaN layer are sequentially grown. The insertion layer includes an AlN layer and a superlattice layer. The superlattice layer includes a P-AlN layer, a P-InN layer, and a P-GaN layer stacked sequentially, with a period number ≥ 2.

4. The method for fabricating a light-emitting diode as described in claim 3, characterized in that, The growth temperature of the AlN layer is 800~900℃ and the growth pressure is 50~300 torr; the growth temperature of the superlattice layer is 700~800℃ and the growth pressure is 50~300 torr.

5. The method for fabricating a light-emitting diode as described in claim 3 or 4, characterized in that, The growth temperature of the P-GaN layer in the superlattice layer is higher than that of the P-AlN layer and the P-InN layer.

6. The method for fabricating a light-emitting diode as described in claim 3, characterized in that, The growth atmosphere of the AlN layer is a mixture of N2 and NH3, and the volume ratio of N2 to NH3 is (0.5~2):1; the growth atmosphere of the superlattice layer is a mixture of N2, H2 and NH3, and the volume ratio of N2, H2 and NH3 is 1:(10~20):(5~10).

7. A light-emitting diode, characterized in that, Includes the light-emitting diode epitaxial wafer as described in claim 1 or 2.

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