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

Abstract

The present invention discloses a light-emitting diode epitaxial wafer, a preparation method thereof, and a light-emitting diode, relating to the technical field of semiconductors. The light-emitting diode epitaxial wafer includes a substrate, a buffer layer, an N-type semiconductor layer, a low-temperature stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer; the multi-quantum well light-emitting layer includes a first sub-layer, a second sub-layer, a third sub-layer, and a fourth sub-layer which are sequentially stacked, and the first sub-layer, the second sub-layer, the third sub-layer, and the fourth sub-layer all include periodically and alternately stacked InGaN quantum well layers and GaN quantum barrier layers; an electron injection layer is inserted into at least one of the GaN quantum barrier layers of the first sub-layer, the GaN quantum barrier layer of the second sub-layer, and the GaN quantum barrier layer of the third sub-layer; a hole injection layer is inserted into the GaN quantum barrier layer of the fourth sub-layer. Implementing the present invention can improve the electron-hole matching degree of the multi-quantum well light-emitting layer, thereby improving the light efficiency of the light-emitting diode.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a light-emitting diode epitaxial wafer, a preparation method thereof, and a light-emitting diode. Background Art

[0002] The epitaxial structure of an LED generally includes a substrate and an N-type semiconductor layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer stacked in sequence. For GaN-based LEDs, the electron-hole concentration injected into the multi-quantum well light-emitting layer is extremely mismatched. Since the effective mass of electrons is less than that of holes, the moving speed of electrons in the semiconductor is much higher than that of holes. Therefore, electrons and holes usually recombine in several quantum wells close to the P-type semiconductor layer, and the quantum wells close to the N-type semiconductor layer hardly emit light. In addition, the electron blocking layer will also block the injection of holes into the multi-quantum well light-emitting layer, resulting in a more serious problem of mismatched electron-hole concentration in the multi-quantum well light-emitting layer, seriously affecting the light-emitting efficiency of the LED. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a light-emitting diode epitaxial wafer and a preparation method thereof, which can improve the matching degree of electron-hole concentration in the multi-quantum well light-emitting layer, thereby improving the light efficiency of the LED device.

[0004] The technical problem to be solved by the present invention is also to provide a light-emitting diode with high light-emitting efficiency.

[0005] To solve the above problems, the present invention discloses a light-emitting diode epitaxial wafer, which includes a substrate, and a buffer layer, an N-type semiconductor layer, a low-temperature stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer stacked in sequence on the substrate;

[0006] The multi-quantum well light-emitting layer includes a first sub-layer, a second sub-layer, a third sub-layer, and a fourth sub-layer stacked in sequence. The first sub-layer, the second sub-layer, the third sub-layer, and the fourth sub-layer each include periodically and alternately stacked InGaN quantum well layers and GaN quantum barrier layers;

[0007] An electron injection layer is inserted into the GaN quantum barrier layer of the first sub-layer, and / or an electron injection layer is inserted into the GaN quantum barrier layer of the second sub-layer, and / or an electron injection layer is inserted into the GaN quantum barrier layer of the third sub-layer; the electron injection layer includes a first AlGaN protection layer, a GaN electron injection layer, and a second AlGaN protection layer stacked in sequence;

[0008] A hole injection layer is inserted into the GaN quantum barrier layer of the fourth sub-layer, and the hole injection layer includes periodically and alternately stacked InGaN hole injection layers and AlGaN hole injection layers.

[0009] As an improvement to the above technical solution, the number of alternating stacking cycles of the hole injection layer is 2 to 5; the InGaN hole injection layer is a Mg-doped InGaN hole injection layer, the In component ratio is 0.01 to 0.08, and the Mg doping concentration is 2.5×10 18 cm -3 ~6.2×10 19 cm -3 , and the thickness is 0.5 nm to 2 nm; the Al component ratio of the AlGaN hole injection layer is 0.01 to 0.08, and the thickness is 0.5 nm to 2 nm.

[0010] As an improvement to the above technical solution, the number of alternating stacking cycles of the fourth sublayer is 2; in the first cycle, the In component ratio of the InGaN quantum well layer is 0.07 to 0.38, the thickness is 2.1 nm to 4.5 nm, and the thickness of the GaN quantum barrier layer is 6 nm to 15 nm; in the second cycle, the InGaN quantum well layer is a Mg-doped InGaN quantum well layer, the In component ratio is 0.07 to 0.38, and the Mg doping concentration is 3.5×10 18 cm -3 ~8.2×10 19 cm -3 , and the thickness is 2.1 nm to 4.5 nm, and the thickness of the GaN quantum barrier layer is 6 nm to 15 nm.

[0011] As an improvement to the above technical solution, the Al component ratio of the first AlGaN protection layer is 0.01 to 0.3, and the thickness is 0.5 nm to 2 nm; the GaN electron injection layer is a Si-doped GaN electron injection layer, and the Si doping concentration is 2.2×10 17 cm -3 ~9.7×10 17 cm -3 , and the thickness is 1 nm to 8 nm; the Al component ratio of the second AlGaN protection layer is 0.01 to 0.3, and the thickness is 0.5 nm to 2 nm.

[0012] As an improvement to the above technical solution, an electron injection layer is inserted into the GaN quantum barrier layer of the first sublayer, the second sublayer and the third sublayer; in each sublayer, the Al component ratio of the first AlGaN protection layer is equal to the Al component ratio of the second AlGaN protection layer;

[0013] From the first sublayer to the third sublayer, the Al component ratio of the first AlGaN protection layer decreases; from the first sublayer to the third sublayer, the Si doping concentration of the GaN electron injection layer decreases.

[0014] As an improvement of the above technical solution, in the electron injection layer of the first sub-layer, the Al component ratio of the first AlGaN protection layer is 0.05 to 0.3, and the Si doping concentration of the GaN electron injection layer is 3.5×10 17 cm -3 ~9.7×10 17 cm -3 , and the Al component ratio of the second AlGaN protection layer is 0.05 to 0.3;

[0015] In the electron injection layer of the second sub-layer, the Al component ratio of the first AlGaN protection layer is 0.03 to 0.23, and the Si doping concentration of the GaN electron injection layer is 2.8×10 17 cm -3 ~7.8×10 17 cm -3 , and the Al component ratio of the second AlGaN protection layer is 0.03 to 0.23;

[0016] In the electron injection layer of the third sub-layer, the Al component ratio of the first AlGaN protection layer is 0.01 to 0.15, and the Si doping concentration of the GaN electron injection layer is 2.2×10 17 cm -3 ~7×10 17 cm -3 , and the Al component ratio of the second AlGaN protection layer is 0.01 to 0.15.

[0017] As an improvement of the above technical solution, the number of alternating stacking cycles of the first sub-layer is 2 to 4, the number of alternating stacking cycles of the second sub-layer is 2 to 6, and the number of alternating stacking cycles of the third sub-layer is 2 to 5; the In component ratio of the InGaN quantum well layer of the first sub-layer, the second sub-layer and the third sub-layer is 0.07 to 0.38, and the thickness is 2.1 nm to 4.5 nm; the GaN quantum barrier layers of the first sub-layer, the second sub-layer and the third sub-layer are all Si-doped GaN quantum barrier layers, and the Si doping concentration is 1.2×10 17 cm -3 ~8.7×10 17 cm -3 , and the thickness is 6 nm to 15 nm.

[0018] Correspondingly, the present invention also discloses a method for preparing a light-emitting diode epitaxial wafer for preparing the above light-emitting diode epitaxial wafer, including the following steps:

[0019] Provide a substrate, and sequentially grow a buffer layer, an N-type semiconductor layer, a low-temperature stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer and a P-type semiconductor layer on the substrate;

[0020] Among them, the multi-quantum well light-emitting layer includes a first sub-layer, a second sub-layer, a third sub-layer, and a fourth sub-layer that are stacked in sequence. The first sub-layer, the second sub-layer, the third sub-layer, and the fourth sub-layer each include periodically alternating InGaN quantum well layers and GaN quantum barrier layers;

[0021] An electron injection layer is inserted into the GaN quantum barrier layer of the first sub-layer, and / or an electron injection layer is inserted into the GaN quantum barrier layer of the second sub-layer, and / or an electron injection layer is inserted into the GaN quantum barrier layer of the third sub-layer; the electron injection layer includes a first AlGaN protective layer, a GaN electron injection layer, and a second AlGaN protective layer that are stacked in sequence;

[0022] A hole injection layer is inserted into the GaN quantum barrier layer of the fourth sub-layer, and the hole injection layer includes periodically alternating InGaN hole injection layers and AlGaN hole injection layers.

[0023] As an improvement of the above technical solution, in the first sub-layer, the growth temperature of the InGaN quantum well layer is 668 °C to 913 °C, the growth pressure is 30 torr to 350 torr, the growth temperature of the GaN quantum barrier layer is 815 °C to 935 °C, and the growth pressure is 30 torr to 350 torr;

[0024] In the second sub-layer, the growth temperature of the InGaN quantum well layer is 668 °C to 913 °C, the growth pressure is 30 torr to 350 torr, the growth temperature of the GaN quantum barrier layer is 815 °C to 935 °C, and the growth pressure is 30 torr to 350 torr;

[0025] In the third sub-layer, the growth temperature of the InGaN quantum well layer is 668 °C to 913 °C, the growth pressure is 30 torr to 350 torr, the growth temperature of the GaN quantum barrier layer is 815 °C to 935 °C, and the growth pressure is 30 torr to 350 torr;

[0026] In the fourth sub-layer, the growth temperature of the InGaN quantum well layer is 668 °C to 913 °C, the growth pressure is 30 torr to 350 torr, the growth temperature of the GaN quantum barrier layer is 815 °C to 920 °C, and the growth pressure is 30 torr to 350 torr.

[0027] Correspondingly, the present invention also discloses a light-emitting diode, and the light-emitting diode includes the above-mentioned light-emitting diode epitaxial wafer.

[0028] Implementing the present invention has the following beneficial effects:

[0029] The multi - quantum - well light - emitting layer of the present invention includes a first sub - layer, a second sub - layer, a third sub - layer, and a fourth sub - layer stacked in sequence. A hole injection layer is inserted into the GaN quantum barrier layer of the fourth sub - layer. The hole injection layer includes periodically and alternately stacked InGaN hole injection layers and AlGaN hole injection layers. The hole injection layer can effectively reduce the blocking effect of the quantum barrier layer material on hole injection, increase the hole concentration injected from the P - type semiconductor layer into the multi - quantum - well light - emitting layer, and enable the quantum wells near the N - type semiconductor layer to also participate in light emission. An electron injection layer is inserted into the GaN quantum barrier layer of at least one of the first sub - layer, the second sub - layer, and the third sub - layer. The electron injection layer can reduce the electron movement rate and effectively prevent electrons from overflowing into the P - type semiconductor layer to cause electron leakage. The multi - quantum - well light - emitting layer structure of the present invention can significantly improve the matching degree of electron - hole concentration in the light - emitting quantum well region and increase the brightness and luminous efficiency of the LED device. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of a light - emitting diode epitaxial wafer provided by an embodiment of the present invention;

[0031] Figure 2 is a schematic structural diagram of a multi - quantum - well light - emitting layer provided by an embodiment of the present invention;

[0032] Figure 3 is a schematic structural diagram of one period of the first sub - layer provided by an embodiment of the present invention;

[0033] Figure 4 is a schematic structural diagram of one period of the second sub - layer provided by an embodiment of the present invention;

[0034] Figure 5 is a schematic structural diagram of one period of the third sub - layer provided by an embodiment of the present invention;

[0035] Figure 6 is a schematic structural diagram of one period of the fourth sub - layer provided by an embodiment of the present invention;

[0036] Figure 7 is a schematic structural diagram of the fourth sub - layer provided by an embodiment of the present invention;

[0037] Figure 8 is a schematic diagram of the preparation process of a light - emitting diode epitaxial wafer provided by an embodiment of the present invention. Detailed Embodiments

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below.

[0039] As Figures 1 to 6As shown, the present invention provides a light-emitting diode epitaxial wafer, including a substrate 100, and a buffer layer 200, an N-type semiconductor layer 300, a low-temperature stress release layer 400, a multi-quantum well light-emitting layer 500, an electron blocking layer 600, and a P-type semiconductor layer 700 that are sequentially stacked on the substrate 100. Among them, the multi-quantum well light-emitting layer 500 includes a first sub-layer 510, a second sub-layer 520, a third sub-layer 530, and a fourth sub-layer 540 that are sequentially stacked. The first sub-layer 510, the second sub-layer 520, the third sub-layer 530, and the fourth sub-layer 540 all include periodically and alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0040] An electron injection layer 10 is inserted into the GaN quantum barrier layer of the first sub-layer 510.

[0041] And / or, an electron injection layer 10 is inserted into the GaN quantum barrier layer of the second sub-layer 520.

[0042] And / or, an electron injection layer 10 is inserted into the GaN quantum barrier layer of the third sub-layer 530.

[0043] The electron injection layer 10 includes a first AlGaN protection layer 11, a GaN electron injection layer 12, and a second AlGaN protection layer 13 that are sequentially stacked.

[0044] A hole injection layer 20 is inserted into the GaN quantum barrier layer of the fourth sub-layer 540. The hole injection layer 20 includes periodically and alternately stacked InGaN hole injection layers 21 and AlGaN hole injection layers 22.

[0045] In some embodiments, the first sub-layer 510, the second sub-layer 520, the third sub-layer 530, and the fourth sub-layer 540 all include at least one InGaN quantum well layer and at least two GaN quantum barrier layers that are periodically and alternately stacked. An electron injection layer 10 is inserted between the GaN quantum barrier layers of the first sub-layer 510, and / or, an electron injection layer 10 is inserted between the GaN quantum barrier layers of the second sub-layer 520, and / or, an electron injection layer 10 is inserted between the GaN quantum barrier layers of the third sub-layer 530.

[0046] A hole injection layer 20 is inserted between the GaN quantum barrier layers of the fourth sub-layer 540.

[0047] Among them, the fourth sub-layer 540 is the sub-layer closest to the P-type semiconductor layer 700 in the multi-quantum well light-emitting layer 500. A hole injection layer 20 is inserted into the GaN quantum barrier layer of the fourth sub-layer 540. The hole injection layer 20 includes periodically and alternately stacked InGaN hole injection layers 21 and AlGaN hole injection layers 22. The AlGaN material with a low bandgap can effectively reduce the blocking effect of the quantum barrier layer material on hole injection, increase the hole concentration injected from the P-type semiconductor layer 700 into the multi-quantum well light-emitting layer 500, and enable the quantum wells close to the N-type semiconductor layer 300 to also participate in light emission.

[0048] In addition to inserting the hole injection layer 20 into the GaN quantum barrier layer of the fourth sub-layer 540, an electron injection layer 10 is inserted into the GaN quantum barrier layer of at least one of the first sub-layer 510, the second sub-layer 520, and the third sub-layer 530. The electron injection layer 10 includes a first AlGaN protection layer 11, a GaN electron injection layer 12, and a second AlGaN protection layer 13 stacked in sequence. The GaN electron injection layer 12 can provide electrons, and the first AlGaN protection layer 11 and the second AlGaN protection layer 13 can block electrons and reduce the electron movement rate, preventing electrons from overflowing into the P-type semiconductor layer 700 and causing electron leakage. By adopting the structure of the multi-quantum well light-emitting layer 500 provided by the present invention, the matching degree of electron-hole concentration in the light-emitting quantum well region can be significantly improved, and the brightness and light efficiency of the LED device can be increased.

[0049] It can be understood that, as Figures 2 to 6 shown, the first sub-layer 510 includes periodically and alternately stacked first InGaN quantum well layers 511 and first GaN quantum barrier layers 512, the second sub-layer 520 includes periodically and alternately stacked second InGaN quantum well layers 521 and second GaN quantum barrier layers 522, the third sub-layer 530 includes periodically and alternately stacked third InGaN quantum well layers 531 and third GaN quantum barrier layers 532, and the fourth sub-layer 540 includes periodically and alternately stacked fourth InGaN quantum well layers 541 and fourth GaN quantum barrier layers 542. An electron injection layer 10 is inserted into at least one of the first GaN quantum barrier layer 512, the second GaN quantum barrier layer 522, and the third GaN quantum barrier layer 532, and a hole injection layer 20 is inserted into the fourth GaN quantum barrier layer 542.

[0050] Specifically, as Figures 3 to 5As shown, in one embodiment, an electron injection layer 10 is inserted into the first GaN quantum barrier layer 512, that is, one period of the first sublayer 510 includes a first InGaN quantum well layer 511, a first GaN quantum barrier first sublayer 512a, an electron injection layer 10 and a first GaN quantum barrier second sublayer 512b stacked in sequence. The growth conditions of the first GaN quantum barrier first sublayer 512a and the first GaN quantum barrier second sublayer 512b are the same, and the thicknesses can be the same or different.

[0051] An electron injection layer 10 is inserted into the second GaN quantum barrier layer 522, that is, one period of the second sublayer 520 includes a second InGaN quantum well layer 521, a second GaN quantum barrier first sublayer 522a, an electron injection layer 10, and a second GaN quantum barrier second sublayer 522b stacked in sequence. The growth conditions of the second GaN quantum barrier first sublayer 522a and the second GaN quantum barrier second sublayer 522b are the same, and the thicknesses can be the same or different.

[0052] The electron injection layer 10 is inserted into the third GaN quantum barrier layer 532, that is, one period of the third sublayer 530 includes a third InGaN quantum well layer 531, a third GaN quantum barrier first sublayer 532a, an electron injection layer 10 and a third GaN quantum barrier second sublayer 532b stacked in sequence. The growth conditions of the third GaN quantum barrier first sublayer 532a and the third GaN quantum barrier second sublayer 532b are the same, and the thicknesses can be the same or different.

[0053] The electron injection layer 10 includes a first AlGaN protective layer 11, a GaN electron injection layer 12, and a second AlGaN protective layer 13 stacked in sequence. The Al component ratio of the first AlGaN protective layer 11 is 0.01-0.3, and is 0.05, 0.1, 0.15, 0.2, or 0.25, but not limited thereto, and the thickness is 0.5 nm-2 nm, and is 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, or 1.8 nm, but not limited thereto. The GaN electron injection layer 12 is a Si-doped GaN electron injection layer, and the Si doping concentration is 2.2×10 17 cm -3 ~9.7×10 17 cm -3 , an exemplary value is 2.5×10 17 cm -3 , 3×10 17 cm -3 , 3.5×10 17 cm -3 , 5×10 17 cm -3 or 7×10 17 cm -3, but not limited thereto, the thickness is 1 nm to 8 nm, and exemplary values are 2 nm, 3 nm, 5 nm, 6 nm or 7 nm, but not limited thereto. The Al component ratio of the second AlGaN protective layer 13 is 0.01 to 0.3, and exemplary values are 0.05, 0.1, 0.15, 0.2 or 0.25, but not limited thereto. The thickness is 0.5 nm to 2 nm, and exemplary values are 0.8 nm, 1 nm, 1.2 nm, 1.5 nm or 1.8 nm, but not limited thereto. The GaN electron injection layer 12 is used to provide electrons. The first AlGaN protective layer 11 and the second AlGaN protective layer 13 are used to protect the GaN electron injection layer 12, preventing electron overflow in the GaN electron injection layer 12 and injecting into the P-type semiconductor layer 700 to cause electron leakage.

[0054] More preferably, an electron injection layer 10 is inserted into the GaN quantum barrier layers of the first sub-layer 510, the second sub-layer 520 and the third sub-layer 530. In each sub-layer, the Al component ratio of the first AlGaN protective layer 11 is equal to the Al component ratio of the second AlGaN protective layer 13. From the first sub-layer 510 to the third sub-layer 530, the Al component ratio of the first AlGaN protective layer 11 decreases. Among them, the Al component ratios of the first AlGaN protective layer 11 and the second AlGaN protective layer 13 in the first sub-layer 510 and the second sub-layer 520 are relatively high. The energy band gap of the quantum barrier layer of the high-Al component material is high, which can confine electrons in front of the first GaN quantum barrier layer 512 and the second GaN quantum barrier layer 522, playing a role in blocking electrons and reducing the electron movement rate, effectively preventing electron overflow and even injecting into the P-type semiconductor layer 700 to cause electron leakage, thereby improving the performance of the LED device such as the yield. From the first sub-layer 510 to the third sub-layer 530, the Si doping concentration of the GaN electron injection layer 12 decreases, while improving the matching degree of the electron-hole concentration in the light-emitting quantum well region, further avoiding electron injection into the P-type semiconductor layer 700 to cause electron leakage.

[0055] In one embodiment, in the electron injection layer 10 of the first sub-layer 510, the Al component ratio of the first AlGaN protective layer 11 is 0.05 to 0.3, and exemplary values are 0.08, 0.1, 0.15, 0.2 or 0.25, but not limited thereto; the Si doping concentration of the GaN electron injection layer 12 is 3.5×10 17 cm -3 ~9.7×10 17 cm -3 , and exemplary values are 5×10 17 cm -3 、5.5×10 17 cm -3 、6×10 17 cm -3 、7×1017 cm -3 or 8×10 17 cm -3 , but not limited thereto; the Al composition ratio of the second AlGaN protection layer 13 is 0.05 to 0.3, and exemplary values are 0.08, 0.1, 0.15, 0.2, or 0.25, but not limited thereto.

[0056] In the electron injection layer 10 of the second sublayer 520, the Al composition ratio of the first AlGaN protection layer 11 is 0.03 to 0.23, and exemplary values are 0.05, 0.08, 0.1, 0.15, or 0.2, but not limited thereto; the Si doping concentration of the GaN electron injection layer 12 is 2.8×10 17 cm -3 ~7.8×10 17 cm -3 , and exemplary values are 3×10 17 cm -3 , 4×10 17 cm -3 , 5×10 17 cm -3 , 6×10 17 cm -3 or 7×10 17 cm -3 , but not limited thereto; the Al composition ratio of the second AlGaN protection layer 13 is 0.03 to 0.23, and exemplary values are 0.05, 0.08, 0.1, 0.15, or 0.2, but not limited thereto.

[0057] In the electron injection layer 10 of the third sublayer 530, the Al composition ratio of the first AlGaN protection layer 11 is 0.01 to 0.15, and exemplary values are 0.02, 0.04, 0.06, 0.08, or 0.1, but not limited thereto; the Si doping concentration of the GaN electron injection layer 12 is 2.2×10 17 cm -3 ~7×10 17 cm -3 , and exemplary values are 2.5×10 17 cm -3 , 3×10 17 cm -3 , 4×10 17 cm -3 , 5×10 17 cm -3 or 6×10 17 cm -3 , but not limited thereto; the Al composition ratio of the second AlGaN protection layer 13 is 0.01 to 0.15, and exemplary values are 0.02, 0.04, 0.06, 0.08, or 0.1, but not limited thereto.

[0058] Specifically, as Figure 6 shown, in one embodiment, a hole injection layer 20 is inserted into the fourth GaN quantum barrier layer 542, that is, one period of the fourth sub-layer 540 includes a fourth InGaN quantum well layer 541, a first sub-layer 542a of the fourth GaN quantum barrier, a hole injection layer 20, and a second sub-layer 542b of the fourth GaN quantum barrier, which are stacked in sequence. The growth conditions of the first sub-layer 542a and the second sub-layer 542b of the fourth GaN quantum barrier are the same, and the thicknesses can be the same or different.

[0059] The hole injection layer 20 includes periodically and alternately stacked InGaN hole injection layers 21 and AlGaN hole injection layers 22. The number of alternating stacking periods of the hole injection layer 20 is 2 to 5, and exemplary values are 3 or 4. The InGaN hole injection layer 21 is a Mg-doped InGaN hole injection layer, and the In component accounts for 0.01 to 0.08, and exemplary values are 0.02, 0.03, 0.05, 0.06, or 0.07, but not limited thereto. The Mg doping concentration is 2.5×10 18 cm -3 ~6.2×10 19 cm -3 Exemplary values are 5×10 18 cm -3 、7.5×10 18 cm -3 、1×10 19 cm -3 、2.5×10 19 cm -3 or 5×10 19 cm -3 but not limited thereto, and the thickness is 0.5 nm to 2 nm, and exemplary values are 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, or 1.8 nm, but not limited thereto. The Al component of the AlGaN hole injection layer 22 accounts for 0.01 to 0.08, and exemplary values are 0.02, 0.03, 0.05, 0.06, or 0.07, but not limited thereto, and the thickness is 0.5 nm to 2 nm, and exemplary values are 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, or 1.8 nm, but not limited thereto. The InGaN hole injection layer 21 is a Mg-doped InGaN hole injection layer, which can provide some holes to participate in radiative recombination luminescence in the luminescent quantum well region to improve the matching degree of the electron-hole concentration in the luminescent quantum well region. The Al component of the AlGaN hole injection layer 22 has a relatively low proportion, which can reduce the blocking effect of the fourth sub-layer 540 on hole injection.

[0060] As Figure 7As shown, in a preferred embodiment, the number of alternating stacking cycles of the fourth sub-layer 540 is 2. Specifically, in the first cycle, the In composition ratio of the fourth InGaN quantum well layer 541A is 0.07 to 0.38, exemplarily 0.1, 0.15, 0.2, 0.3 or 0.35, but not limited thereto, and the thickness is 2.1 nm to 4.5 nm, exemplarily 2.5 nm, 3 nm, 3.2 nm, 3.6 nm or 4 nm, but not limited thereto. The thickness of the fourth GaN quantum barrier layer 542A is 6 nm to 15 nm, exemplarily 8 nm, 9 nm, 10 nm, 12 nm or 14 nm, but not limited thereto. In the second cycle, the fourth InGaN quantum well layer 541B is a Mg-doped InGaN quantum well layer, the In composition ratio is 0.07 to 0.38, exemplarily 0.1, 0.15, 0.2, 0.3 or 0.35, but not limited thereto, and the Mg doping concentration is 3.5×10 18 cm -3 ~8.2×10 19 cm -3 exemplarily 5×10 18 cm -3 、7.5×10 18 cm -3 、1×10 19 cm -3 、2.5×10 19 cm -3 or 5×10 19 cm -3 but not limited thereto, and the thickness is 2.1 nm to 4.5 nm, exemplarily 2.5 nm, 3 nm, 3.2 nm, 3.6 nm or 4 nm, but not limited thereto. The thickness of the fourth GaN quantum barrier layer 542B is 6 nm to 15 nm, exemplarily 8 nm, 9 nm, 10 nm, 12 nm or 14 nm, but not limited thereto. In the fourth sub-layer 540, the fourth InGaN quantum well layer 541A in the first cycle is not intentionally doped, and the fourth InGaN quantum well layer 541B in the second cycle is doped with a low concentration of Mg, which can provide a certain number of holes while ensuring the luminous efficiency of the multi-quantum well light-emitting region close to the P-type semiconductor layer 700. The holes move towards the N-type semiconductor 300 side, thereby improving the matching degree of the hole-electron concentration in the multi-quantum well light-emitting layer 500.

[0061] In one embodiment, the number of alternating stacking periods of the first sublayer 510 is 2 to 4, the number of alternating stacking periods of the second sublayer 520 is 2 to 6, and the number of alternating stacking periods of the third sublayer 530 is 2 to 5. The In component ratio of the InGaN quantum well layer (i.e., the first InGaN quantum well layer 511, the second InGaN quantum well layer 521, and the third InGaN quantum well layer 531) of the first sublayer 510, the second sublayer 520, and the third sublayer 530 is 0.07 to 0.38, exemplarily 0.1, 0.15, 0.2, 0.25, or 0.3, but not limited thereto, and the thickness is 2.1 nm to 4.5 nm, exemplarily 2.5 nm, 3 nm, 3.5 nm, 4 nm, or 4.2 nm, but not limited thereto. The GaN quantum barrier layers of the first sublayer 510, the second sublayer 520, and the third sublayer 530 (i.e., the first GaN quantum barrier layer 512, the second GaN quantum barrier layer 522, and the third GaN quantum barrier layer 532) are all Si-doped GaN quantum barrier layers, and the Si doping concentration is 1.2×10 17 cm -3 ~8.7×10 17 cm -3 , exemplarily 3×10 17 cm -3 , 4×10 17 cm -3 , 5×10 17 cm -3 , 6×10 17 cm -3 or 7×10 17 cm -3 , but not limited thereto, the thickness is 6nm~15nm, exemplarily 8nm, 9nm, 10nm, 12nm or 14nm, but not limited thereto.

[0062] In a preferred embodiment, the Si doping concentration of the first GaN quantum barrier layer 512 is 2.5×10 17 cm -3 ~8.7×10 17 cm -3 ; The Si doping concentration of the second GaN quantum barrier layer 522 is 1.8×10 17 cm -3 ~6.8×10 17 cm -3 ; The Si doping concentration of the third GaN quantum barrier layer 532 is 1.2×10 17 cm -3 ~6×10 17 cm -3, from the first sub-layer 510 to the third sub-layer 530, the Si doping concentrations of the first GaN quantum barrier layer 512, the second GaN quantum barrier layer 522, and the third GaN quantum barrier layer 532 decrease, avoiding electron leakage caused by electron injection into the P-type semiconductor layer 700.

[0063] Except for the multi-quantum well light-emitting layer 500, the characteristics of other layer structures of the present invention are as follows:

[0064] The substrate 100 can be one of a sapphire substrate, a sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, and a zinc oxide substrate. In one embodiment, the substrate 100 is a sapphire substrate. 2 a sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, and a zinc oxide substrate. In one embodiment, the substrate 100 is a sapphire substrate.

[0065] The buffer layer 200 can be an AlN buffer layer and / or an AlGaN buffer layer. In one embodiment, the buffer layer 200 is an AlN buffer layer with a thickness of 20 nm to 200 nm.

[0066] The N-type semiconductor layer 300 includes an undoped GaN layer and an N-type GaN layer. The thickness of the undoped GaN layer is 1 μm to 5 μm, the thickness of the N-type GaN layer is 2 μm to 3 μm, and the Si doping concentration is 1×10 19 cm -3 ~5×10 19 cm -3 .

[0067] The low-temperature stress relaxation layer 400 can include periodically alternating InGaN stress relaxation layers and GaN stress relaxation layers, and the number of alternating growth cycles is 2 to 10. The thickness of the InGaN stress relaxation layer is 1 nm to 3 nm, and the thickness of the GaN stress relaxation layer is 15 nm to 30 nm. The growth temperature of the low-temperature stress relaxation layer 400 is 800 °C to 900 °C.

[0068] The electron blocking layer 600 can be an AlGaN electron blocking layer with a thickness of 10 nm to 100 nm and an Al component ratio of 0.4 to 0.8.

[0069] The P-type semiconductor layer 700 can be a P-type GaN layer with a thickness of 10 nm to 50 nm and an Mg doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 .

[0070] Correspondingly, as Figure 8 shown, the present invention also provides a method for manufacturing a light-emitting diode epitaxial wafer for manufacturing the above-mentioned light-emitting diode epitaxial wafer, including the following steps:

[0071] S1. Provide a substrate 100.

[0072] S2. Sequentially grow a buffer layer 200, an N-type semiconductor layer 300, a low-temperature stress release layer 400, a multi-quantum well light-emitting layer 500, an electron blocking layer 600, and a P-type semiconductor layer 700 on the substrate 100.

[0073] Specifically, the multi-quantum well light-emitting layer 500 includes a first sub-layer 510, a second sub-layer 520, a third sub-layer 530, and a fourth sub-layer 540 stacked in sequence.

[0074] In one embodiment, the preparation of the first sub-layer 510 includes the following steps: control the growth temperature to be 668°C to 913°C, the growth pressure to be 30 torr to 350 torr, introduce an In source, a Ga source, and an N source, and grow a first InGaN quantum well layer 511; control the growth temperature to be 815°C to 935°C, the growth pressure to be 30 torr to 350 torr, introduce a Ga source and an N source, and grow a first GaN quantum barrier layer 512; repeat the periodic stacking and growth of the first InGaN quantum well layer 511 and the first GaN quantum barrier layer 512.

[0075] In a preferred embodiment, the growth of each cycle of the first sub-layer 510 includes the following steps:

[0076] Control the growth temperature to be 668°C to 913°C, the growth pressure to be 30 torr to 350 torr, introduce an In source, a Ga source, and an N source, and grow a first InGaN quantum well layer 511; control the growth temperature to be 815°C to 920°C, the growth pressure to be 30 torr to 350 torr, introduce a Ga source, an N source, and an Si source, and grow a first sub-layer 512a of the first GaN quantum barrier; control the growth temperature to be 815°C to 920°C, the growth pressure to be 30 torr to 350 torr, introduce an Al source, a Ga source, and an N source, and grow a first AlGaN protective layer 11; control the growth temperature to be 850°C to 935°C, the growth pressure to be 30 torr to 350 torr, introduce a Ga source, an N source, and an Si source, and grow a GaN electron injection layer 12; control the growth temperature to be 815°C to 920°C, the growth pressure to be 30 torr to 350 torr, introduce an Al source, a Ga source, and an N source, and grow a second AlGaN protective layer 13; control the growth temperature to be 815°C to 920°C, the growth pressure to be 30 torr to 350 torr, introduce a Ga source, an N source, and an Si source, and grow a second sub-layer 512b of the first GaN quantum barrier.

[0077] In one embodiment, the preparation of the second sub-layer 520 includes the following steps: controlling the growth temperature to be 668 °C to 913 °C, the growth pressure to be 30 torr to 350 torr, introducing an In source, a Ga source, and an N source, and growing the second InGaN quantum well layer 521; controlling the growth temperature to be 815 °C to 935 °C, the growth pressure to be 30 torr to 350 torr, introducing a Ga source and an N source, and growing the second GaN quantum barrier layer 522; repeating the periodic stacking and growing the second InGaN quantum well layer 521 and the second GaN quantum barrier layer 522.

[0078] In a preferred embodiment, the growth of each period of the second sub-layer 520 includes the following steps:

[0079] Controlling the growth temperature to be 668 °C to 913 °C, the growth pressure to be 30 torr to 350 torr, introducing an In source, a Ga source, and an N source, and growing the second InGaN quantum well layer 521; controlling the growth temperature to be 815 °C to 920 °C, the growth pressure to be 30 torr to 350 torr, introducing a Ga source, an N source, and an Si source, and growing the first sub-layer 522a of the second GaN quantum barrier; controlling the growth temperature to be 815 °C to 920 °C, the growth pressure to be 30 torr to 350 torr, introducing an Al source, a Ga source, and an N source, and growing the first AlGaN protection layer 11; controlling the growth temperature to be 850 °C to 935 °C, the growth pressure to be 30 torr to 350 torr, introducing a Ga source, an N source, and an Si source, and growing the GaN electron injection layer 12; controlling the growth temperature to be 815 °C to 920 °C, the growth pressure to be 30 torr to 350 torr, introducing an Al source, a Ga source, and an N source, and growing the second AlGaN protection layer 13; controlling the growth temperature to be 815 °C to 920 °C, the growth pressure to be 30 torr to 350 torr, introducing a Ga source, an N source, and an Si source, and growing the second sub-layer 522b of the second GaN quantum barrier.

[0080] In one embodiment, the preparation of the third sub-layer 530 includes the following steps: controlling the growth temperature to be 668 °C to 913 °C, the growth pressure to be 30 torr to 350 torr, introducing an In source, a Ga source, and an N source, and growing the third InGaN quantum well layer 531; controlling the growth temperature to be 815 °C to 935 °C, the growth pressure to be 30 torr to 350 torr, introducing a Ga source and an N source, and growing the third GaN quantum barrier layer 532; repeating the periodic stacking and growing the third InGaN quantum well layer 531 and the third GaN quantum barrier layer 532.

[0081] In a preferred embodiment, the growth of each period of the third sub-layer 530 includes the following steps:

[0082] The growth temperature is controlled to be 668 °C to 913 °C, the growth pressure is 30 torr to 350 torr, an In source, a Ga source and an N source are introduced, and the third InGaN quantum well layer 531 is grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, a Ga source, an N source and a Si source are introduced, and the first sub-layer 532a of the third GaN quantum barrier is grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, an Al source, a Ga source and an N source are introduced, and the first AlGaN protection layer 11 is grown; the growth temperature is controlled to be 850 °C to 935 °C, the growth pressure is 30 torr to 350 torr, a Ga source, an N source and a Si source are introduced, and the GaN electron injection layer 12 is grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, an Al source, a Ga source and an N source are introduced, and the second AlGaN protection layer 13 is grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, a Ga source, an N source and a Si source are introduced, and the second sub-layer 532b of the third GaN quantum barrier is grown.

[0083] In an embodiment, the preparation of the fourth sub-layer 540 includes the following steps: the growth temperature is controlled to be 668 °C to 913 °C, the growth pressure is 30 torr to 350 torr, an In source, a Ga source and an N source are introduced, and the fourth InGaN quantum well layer 541 is grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, a Ga source and an N source are introduced, and the fourth GaN quantum barrier layer 542 is grown; the fourth InGaN quantum well layer 541 and the fourth GaN quantum barrier layer 542 are repeatedly stacked and periodically grown.

[0084] In a preferred embodiment, the growth of each period of the fourth sub-layer 540 includes the following steps:

[0085] The growth temperature is controlled to be 668 °C to 913 °C, the growth pressure is 30 torr to 350 torr, an In source, a Ga source, and an N source are introduced, and the fourth InGaN quantum well layer 541 is grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, a Ga source and an N source are introduced, and the first sub-layer 542a of the fourth GaN quantum barrier is grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, an In source, a Ga source, an N source, and an Mg source are introduced, and the InGaN hole injection layer 21 is grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, an Al source, a Ga source, and an N source are introduced, and the AlGaN hole injection layer 22 is grown; the InGaN hole injection layer 21 and the AlGaN hole injection layer 22 are repeatedly stacked and periodically grown; the growth temperature is controlled to be 815 °C to 920 °C, the growth pressure is 30 torr to 350 torr, a Ga source and an N source are introduced, and the second sub-layer 542b of the fourth GaN quantum barrier is grown.

[0086] Preferably, the preparation of the fourth sub-layer 540 includes the following steps: controlling the growth temperature to be 668 °C to 913 °C, the growth pressure to be 30 torr to 350 torr, introducing an In source, a Ga source, and an N source, and growing the fourth InGaN quantum well layer 541A; controlling the growth temperature to be 815 °C to 920 °C, the growth pressure to be 30 torr to 350 torr, introducing a Ga source and an N source, and growing the fourth GaN quantum barrier layer 542A to complete the growth of the first cycle; controlling the growth temperature to be 668 °C to 913 °C, the growth pressure to be 30 torr to 350 torr, introducing an In source, a Ga source, an N source, and an Mg source, and growing the fourth InGaN quantum well layer 541B; controlling the growth temperature to be 815 °C to 920 °C, the growth pressure to be 30 torr to 350 torr, introducing a Ga source and an N source, and growing the fourth GaN quantum barrier layer 542B to complete the growth of the second cycle, that is, growing 2 cycles to obtain the fourth sub-layer 540.

[0087] Correspondingly, the present invention also provides a light-emitting diode, which includes the above-mentioned light-emitting diode epitaxial wafer.

[0088] The present invention will be further described below with specific embodiments:

[0089] Embodiment 1

[0090] This embodiment provides a light-emitting diode epitaxial wafer, which includes a substrate, and a buffer layer, an N-type semiconductor layer, a low-temperature stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer that are sequentially stacked on the substrate.

[0091] The multi - quantum - well light - emitting layer includes a first sub - layer, a second sub - layer, a third sub - layer, and a fourth sub - layer stacked in sequence.

[0092] The first sub - layer includes a first InGaN quantum - well layer and a first GaN quantum - barrier layer stacked periodically and alternately. The number of alternating stacking periods is 3. The In composition ratio of the first InGaN quantum - well layer is 0.2, and the thickness is 3 nm. The first GaN quantum - barrier layer is a Si - doped GaN quantum - barrier layer, and the Si doping concentration is 2.5×10 17 cm -3 , and the thickness is 12 nm. An electron - injection layer is also inserted into the first GaN quantum - barrier layer. The electron - injection layer includes a first AlGaN protective layer, a GaN electron - injection layer, and a second AlGaN protective layer stacked in sequence. The Al composition ratio of the first AlGaN protective layer is 0.15, and the thickness is 1.5 nm. The GaN electron - injection layer is a Si - doped GaN electron - injection layer, and the Si doping concentration is 5×10 17 cm -3 , and the thickness is 5 nm. The Al composition ratio of the second AlGaN protective layer is 0.15, and the thickness is 1.5 nm.

[0093] The second sub - layer includes a second InGaN quantum - well layer and a second GaN quantum - barrier layer stacked periodically and alternately. The number of alternating stacking periods is 4. The In composition ratio of the second InGaN quantum - well layer is 0.2, and the thickness is 3 nm. The second GaN quantum - barrier layer is a Si - doped GaN quantum - barrier layer, and the Si doping concentration is 2.5×10 17 cm -3 , and the thickness is 12 nm.

[0094] The third sub - layer includes a third InGaN quantum - well layer and a third GaN quantum - barrier layer stacked periodically and alternately. The number of alternating stacking periods is 3. The In composition ratio of the third InGaN quantum - well layer is 0.2, and the thickness is 3 nm. The third GaN quantum - barrier layer is a Si - doped GaN quantum - barrier layer, and the Si doping concentration is 2.5×10 17 cm -3 , and the thickness is 12 nm.

[0095] The fourth sub - layer includes a fourth InGaN quantum - well layer and a fourth GaN quantum - barrier layer stacked periodically and alternately. The number of alternating stacking periods is 3. The In composition ratio of the fourth InGaN quantum - well layer is 0.2, and the thickness is 3 nm. The thickness of the fourth GaN quantum - barrier layer is 12 nm. A hole - injection layer is also inserted into the fourth GaN quantum - barrier layer. The hole - injection layer includes an InGaN hole - injection layer and an AlGaN hole - injection layer stacked periodically and alternately. The number of alternating stacking periods is 3. The InGaN hole - injection layer is a Mg - doped InGaN hole - injection layer, the In composition ratio is 0.05, and the Mg doping concentration is 1×1019 cm -3 The thickness is 1.5 nm, and the Al component ratio of the AlGaN hole injection layer is 0.05, with a thickness of 1.5 nm.

[0096] Example 2

[0097] This example provides a light-emitting diode epitaxial wafer, which is different from Example 1 in that the number of periods of the fourth sub-layer alternating stack is 2. For the fourth InGaN quantum well layer in the first period, the In component ratio is 0.2 and the thickness is 3 nm, the thickness of the fourth GaN quantum barrier layer is 12 nm. For the fourth InGaN quantum well layer in the second period, it is a Mg-doped InGaN quantum well layer, the In component ratio is 0.2, and the Mg doping concentration is 7.5×10 18 cm -3 The thickness is 3 nm, and the thickness of the fourth GaN quantum barrier layer is 12 nm.

[0098] The rest are the same as those in Example 1.

[0099] Example 3

[0100] This example provides a light-emitting diode epitaxial wafer, which is different from Example 2 in that electron injection layers are inserted into the first GaN quantum barrier layer, the second GaN quantum barrier layer, and the third GaN quantum barrier layer. The structures of the electron injection layers in the first GaN quantum barrier layer, the second GaN quantum barrier layer, and the third GaN quantum barrier layer are the same, and each includes a first AlGaN protection layer, a GaN electron injection layer, and a second AlGaN protection layer stacked in sequence. The Al component ratio of the first AlGaN protection layer is 0.15, and the thickness is 1.5 nm. The GaN electron injection layer is a Si-doped GaN electron injection layer, and the Si doping concentration is 5×10 17 cm -3 The thickness is 5 nm, the Al component ratio of the second AlGaN protection layer is 0.15, and the thickness is 1.5 nm.

[0101] The rest are the same as those in Example 2.

[0102] Example 4

[0103] This embodiment provides a light-emitting diode epitaxial wafer, which is different from that of Embodiment 3 in that in the electron injection layer of the first GaN quantum barrier layer, the Al component ratio of the first AlGaN protection layer is 0.25, and the Al component ratio of the second AlGaN protection layer is 0.25; in the electron injection layer of the second GaN quantum barrier layer, the Al component ratio of the first AlGaN protection layer is 0.15, and the Al component ratio of the second AlGaN protection layer is 0.15; in the electron injection layer of the third GaN quantum barrier layer, the Al component ratio of the first AlGaN protection layer is 0.05, and the Al component ratio of the second AlGaN protection layer is 0.05.

[0104] The rest are the same as those in Embodiment 3.

[0105] Embodiment 5

[0106] This embodiment provides a light-emitting diode epitaxial wafer, which is different from that of Embodiment 4 in that in the electron injection layer of the first GaN quantum barrier layer, the Si doping concentration of the GaN electron injection layer is 8×10 17 cm -3 ; in the electron injection layer of the second GaN quantum barrier layer, the Si doping concentration of the GaN electron injection layer is 6×10 17 cm -3 ; in the electron injection layer of the third GaN quantum barrier layer, the Si doping concentration of the GaN electron injection layer is 4×10 17 cm -3 .

[0107] The rest are the same as those in Embodiment 4.

[0108] Comparative Example 1

[0109] This comparative example provides a light-emitting diode epitaxial wafer, which is different from that of Embodiment 1 in that the multi-quantum well light-emitting layer includes periodically alternating stacked InGaN quantum well layers and AlGaN quantum barrier layers, and the number of alternating stacking periods is 12. Among them, the In component ratio in the InGaN quantum well layer is 0.2, the thickness is 3 nm, the Al component ratio in the AlGaN quantum barrier layer is 0.05, and the thickness is 12 nm.

[0110] The rest are the same as those in Embodiment 1.

[0111] Comparative Example 2

[0112] This comparative example provides a light-emitting diode epitaxial wafer, which is different from that of Embodiment 1 in that in the multi-quantum well light-emitting layer, a hole injection layer is not inserted in the fourth GaN quantum barrier layer of the fourth sub-layer.

[0113] The rest are the same as those in Embodiment 1.

[0114] Comparative Example 3

[0115] This comparative example provides a light-emitting diode epitaxial wafer, which is different from that of Example 1 in that an electron injection layer is not inserted into the first GaN quantum barrier layer of the first sublayer in the multi-quantum well light-emitting layer.

[0116] The rest are the same as those of Example 1.

[0117] The light-emitting diode epitaxial wafers prepared in Examples 1 to 5 and Comparative Examples 1 to 3 are made into 15 mil × 15 mil LED chips. On the same LED tester, their luminous efficiency is tested under a current of 120 mA / 60 mA, and the luminous efficiency improvement of Examples 1 to 5, Comparative Example 2, and Comparative Example 3 compared with Comparative Example 1 is calculated. The test results are shown in the following table.

[0118]

[0119] As can be seen from the above table, the light-emitting diode epitaxial wafer provided by the embodiment of the present invention can effectively improve the luminous efficiency of the chip.

[0120] The above is the preferred embodiment of the invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A light emitting diode epitaxial wafer, characterized in that: It includes a substrate, and a buffer layer, an N-type semiconductor layer, a low-temperature stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer and a P-type semiconductor layer sequentially stacked on the substrate; The multi-quantum well light-emitting layer comprises a first sublayer, a second sublayer, a third sublayer and a fourth sublayer stacked in sequence, wherein the first sublayer, the second sublayer, the third sublayer and the fourth sublayer all comprise periodically alternately stacked InGaN quantum well layers and GaN quantum barrier layers; the number of periods of the alternate stacking of the first sublayer is 2 to 4, the number of periods of the alternate stacking of the second sublayer is 2 to 6, the number of periods of the alternate stacking of the third sublayer is 2 to 5, and the number of periods of the alternate stacking of the fourth sublayer is 2; The GaN quantum barrier layers of the first sublayer, the second sublayer and the third sublayer are all inserted with electron injection layers; the electron injection layer comprises a first AlGaN protective layer, a GaN electron injection layer and a second AlGaN protective layer stacked in sequence; the GaN electron injection layer is a Si-doped GaN electron injection layer, and the Si doping concentration is 2.2×10 17 cm -3 ~ 9.7×10 17 cm -3 ; A hole injection layer is inserted into the GaN quantum barrier layer of the fourth sublayer, and the hole injection layer includes periodically alternately stacked InGaN hole injection layers and AlGaN hole injection layers, and the number of periods of the alternately stacked hole injection layers is 2 to 5; the InGaN hole injection layer is a Mg-doped InGaN hole injection layer, the In component accounts for 0.01 to 0.08, and the Mg doping concentration is 2.5×10 18 cm -3 ~6.2×10 19 cm -3 ; In each sublayer, the Al component ratio of the first AlGaN protective layer is equal to the Al component ratio of the second AlGaN protective layer; from the first sublayer to the third sublayer, the Al component ratio of the first AlGaN protective layer decreases; from the first sublayer to the third sublayer, the Si doping concentration of the GaN electron injection layer decreases.

2. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The thickness of the InGaN hole injection layer is 0.5nm~2nm; the Al component ratio of the AlGaN hole injection layer is 0.01~0.08, and the thickness is 0.5nm~2nm.

3. The light emitting diode epitaxial wafer according to claim 1, characterized in that: In the first period of the fourth sublayer, the In component ratio of the InGaN quantum well layer is 0.07-0.38, the thickness is 2.1nm-4.5nm, and the thickness of the GaN quantum barrier layer is 6nm-15nm; in the second period, the InGaN quantum well layer is a Mg-doped InGaN quantum well layer, the In component ratio is 0.07-0.38, and the Mg doping concentration is 3.5×10 18 cm -3 ~8.2×10 19 cm -3 , with a thickness of 2.1nm~4.5nm, and the thickness of the GaN quantum barrier layer is 6nm~15nm.

4. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The Al component ratio of the first AlGaN protective layer is 0.01-0.3, and the thickness is 0.5nm-2nm; the thickness of the GaN electron injection layer is 1nm-8nm; the Al component ratio of the second AlGaN protective layer is 0.01-0.3, and the thickness is 0.5nm-2nm.

5. The light emitting diode epitaxial wafer according to claim 1, characterized in that: In the electron injection layer of the first sub-layer, the Al component ratio of the first AlGaN protective layer is 0.05-0.3, and the Si doping concentration of the GaN electron injection layer is 3.5×10 17 cm -3 ~9.7×10 17 cm -3 , the Al component ratio of the second AlGaN protective layer is 0.05~0.3; In the electron injection layer of the second sub-layer, the Al component ratio of the first AlGaN protective layer is 0.03-0.23, and the Si doping concentration of the GaN electron injection layer is 2.8×10 17 cm -3 ~7.8×10 17 cm -3 , the Al component ratio of the second AlGaN protective layer is 0.03~0.23; In the electron injection layer of the third sub-layer, the Al component ratio of the first AlGaN protective layer is 0.01-0.15, and the Si doping concentration of the GaN electron injection layer is 2.2×10 17 cm -3 ~7×10 17 cm -3 , the Al component ratio of the second AlGaN protective layer is 0.01~0.

15.

6. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The In component ratio of the InGaN quantum well layer of the first sublayer, the second sublayer and the third sublayer is 0.07-0.38, and the thickness is 2.1nm-4.5nm; the GaN quantum barrier layers of the first sublayer, the second sublayer and the third sublayer are all Si-doped GaN quantum barrier layers, and the Si doping concentration is 1.2×10 17 cm -3 ~8.7×10 17 cm -3 , thickness is 6nm~15nm.

7. A method for preparing a light emitting diode epitaxial wafer, for preparing the light emitting diode epitaxial wafer according to any one of claims 1 to 6, characterized in that: The following steps are involved: Providing a substrate, and sequentially growing a buffer layer, an N-type semiconductor layer, a low-temperature stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer on the substrate; The multi-quantum well light-emitting layer comprises a first sublayer, a second sublayer, a third sublayer and a fourth sublayer stacked in sequence, wherein the first sublayer, the second sublayer, the third sublayer and the fourth sublayer all comprise periodically alternately stacked InGaN quantum well layers and GaN quantum barrier layers; An electron injection layer is inserted into the GaN quantum barrier layer of the first sublayer, and / or an electron injection layer is inserted into the GaN quantum barrier layer of the second sublayer, and / or an electron injection layer is inserted into the GaN quantum barrier layer of the third sublayer; the electron injection layer comprises a first AlGaN protective layer, a GaN electron injection layer and a second AlGaN protective layer stacked in sequence; A hole injection layer is inserted into the GaN quantum barrier layer of the fourth sub-layer, and the hole injection layer includes an InGaN hole injection layer and an AlGaN hole injection layer that are periodically and alternately stacked.

8. The method for preparing a light emitting diode epitaxial wafer according to claim 7, characterized in that: In the first sublayer, the growth temperature of the InGaN quantum well layer is 668°C to 913°C, the growth pressure is 30torr to 350torr, and the growth temperature of the GaN quantum barrier layer is 815°C to 935°C, the growth pressure is 30torr to 350torr; In the second sublayer, the growth temperature of the InGaN quantum well layer is 668°C to 913°C, the growth pressure is 30torr to 350torr, and the growth temperature of the GaN quantum barrier layer is 815°C to 935°C, the growth pressure is 30torr to 350torr; In the third sublayer, the growth temperature of the InGaN quantum well layer is 668° C. to 913° C., the growth pressure is 30 torr to 350 torr, and the growth temperature of the GaN quantum barrier layer is 815° C. to 935° C., the growth pressure is 30 torr to 350 torr; In the fourth sublayer, the growth temperature of the InGaN quantum well layer is 668° C. to 913° C., and the growth pressure is 30 torr to 350 torr; the growth temperature of the GaN quantum barrier layer is 815° C. to 920° C., and the growth pressure is 30 torr to 350 torr.

9. A light emitting diode, characterized in that: The light emitting diode comprises the light emitting diode epitaxial wafer as described in any one of claims 1 to 6.

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