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

Abstract

The invention discloses a light-emitting diode epitaxial wafer, a preparation method thereof and a light-emitting diode, and relates to the technical field of semiconductors. The light-emitting diode epitaxial wafer comprises 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 comprises a first sub-layer, a second sub-layer, a third sub-layer and a fourth sub-layer which are stacked in sequence, and each of the first sub-layer, the second sub-layer, the third sub-layer and the fourth sub-layer comprises an InGaN quantum well layer and a GaN quantum barrier layer which are periodically and alternately stacked; an electron injection layer is inserted into at least one of the GaN quantum barrier layer 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; and a hole injection layer is inserted into the GaN quantum barrier layer of the fourth sub-layer. By implementing the invention, the electron hole matching degree of the multi-quantum well light-emitting layer can be improved, so that the luminous efficiency of the light-emitting diode is improved.

Description

Technical Field

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

[0002] The epitaxial structure of LED generally includes a substrate and a sequentially stacked N-type semiconductor layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer. For GaN-based LEDs, the concentration of electrons and holes 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 movement speed of electrons in semiconductors 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 mismatch in the concentration of electrons and holes in the multi-quantum well light-emitting layer, which seriously affects the luminous 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 the 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] In order to solve the above problems, the present invention discloses a light-emitting diode epitaxial wafer, comprising 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 InGaN quantum well layers and GaN quantum barrier layers stacked alternately and periodically; 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.

[0006] As an improvement of the above technical solution, the number of cycles of the alternate stacking 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 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 , with a thickness of 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.

[0007] As an improvement of the above technical solution, the number of cycles of the alternating stacking of the fourth sublayer is 2; in the first cycle, 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 cycle, 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.

[0008] As an improvement of the above technical solution, the Al component ratio of the first AlGaN protective layer is 0.01-0.3, and the thickness is 0.5nm-2nm; 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 , with a thickness of 1nm~8nm; the Al component ratio of the second AlGaN protective layer is 0.01~0.3, and the thickness is 0.5nm~2nm.

[0009] As an improvement of 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 protective layer is equal to the Al component ratio of the second AlGaN protective layer; From the first sub-layer to the third sub-layer, the Al component ratio of the first AlGaN protective layer decreases; from the first sub-layer to the third sub-layer, the Si doping concentration of the GaN electron injection layer decreases.

[0010] 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 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.

[0011] As an improvement of the above technical solution, the number of periods of the alternating stacking of the first sublayer is 2-4, the number of periods of the alternating stacking of the second sublayer is 2-6, and the number of periods of the alternating stacking of the third sublayer is 2-5; 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.

[0012] Correspondingly, the present invention also discloses a method for preparing a light-emitting diode epitaxial wafer, which is used to prepare the light-emitting diode epitaxial wafer, and comprises the following steps: 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.

[0013] As an improvement of the above technical solution, in the first sublayer, the growth temperature of the InGaN quantum well layer is 668°C~913°C, the growth pressure is 30torr~350torr, and the growth temperature of the GaN quantum barrier layer is 815°C~935°C, the growth pressure is 30torr~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.

[0014] Correspondingly, the present invention also discloses a light emitting diode, which includes the light emitting diode epitaxial wafer mentioned above.

[0015] The implementation of the present invention has the following beneficial effects: The multi-quantum well light-emitting layer of the present invention comprises a first sublayer, a second sublayer, a third sublayer and a fourth sublayer stacked in sequence, a hole injection layer is inserted into the GaN quantum barrier layer of the fourth sublayer, and the hole injection layer comprises an InGaN hole injection layer and an AlGaN hole injection layer stacked periodically and alternately, and 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 to the multi-quantum well light-emitting layer, and allow the quantum well close to the N-type semiconductor layer to participate in light emission; an electron injection layer is inserted into the GaN quantum barrier layer of at least one of the first sublayer, the second sublayer and the third sublayer, and the electron injection layer can reduce the electron movement rate and effectively prevent the electron from overflowing to 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 the electron hole concentration in the light-emitting quantum well region, and improve the brightness and light efficiency of the LED device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of a light emitting diode epitaxial wafer provided by an embodiment of the present invention; Figure 2 is a schematic structural diagram of a multi-quantum well light-emitting layer provided in an embodiment of the present invention; Figure 3 is a schematic diagram of the structure of one period of the first sub-layer provided by an embodiment of the present invention; Figure 4 is a schematic structural diagram of one period of the second sub-layer provided by an embodiment of the present invention; Figure 5 is a schematic diagram of the structure of one period of the third sub-layer provided by an embodiment of the present invention; Figure 6 is a schematic structural diagram of one period of the fourth sublayer provided by an embodiment of the present invention; Figure 7 is a schematic structural diagram of the fourth sublayer provided in an embodiment of the present invention; Figure 8 It is a schematic diagram of the preparation process of a light-emitting diode epitaxial wafer provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0018] like Figure 1 to Figure 6As shown, the present invention provides a light-emitting diode epitaxial wafer, comprising 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 sequentially stacked on the substrate 100. The multi-quantum well light-emitting layer 500 comprises a first sublayer 510, a second sublayer 520, a third sublayer 530 and a fourth sublayer 540 stacked in sequence, and the first sublayer 510, the second sublayer 520, the third sublayer 530 and the fourth sublayer 540 all comprise periodically alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0019] An electron injection layer 10 is inserted into the GaN quantum barrier layer of the first sublayer 510. and / or, an electron injection layer 10 is inserted into the GaN quantum barrier layer of the second sublayer 520, And / or, the electron injection layer 10 is inserted into the GaN quantum barrier layer of the third sub-layer 530 .

[0020] 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 this order.

[0021] A hole injection layer 20 is inserted into the GaN quantum barrier layer of the fourth sublayer 540 . The hole injection layer 20 includes an InGaN hole injection layer 21 and an AlGaN hole injection layer 22 which are periodically and alternately stacked.

[0022] In some embodiments, the first sublayer 510, the second sublayer 520, the third sublayer 530 and the fourth sublayer 540 each include at least one InGaN quantum well layer and at least two GaN quantum barrier layers that are periodically alternately stacked, and an electron injection layer 10 is inserted between the GaN quantum barrier layers of the first sublayer 510, and / or, an electron injection layer 10 is inserted between the GaN quantum barrier layers of the second sublayer 520, and / or, an electron injection layer 10 is inserted between the GaN quantum barrier layers of the third sublayer 530.

[0023] A hole injection layer 20 is inserted between the GaN quantum barrier layers of the fourth sublayer 540 .

[0024] Among them, the fourth sublayer 540 is the sublayer closest to the P-type semiconductor layer 700 in the multi-quantum well light-emitting layer 500, and a hole injection layer 20 is inserted into the GaN quantum barrier layer of the fourth sublayer 540, and the hole injection layer 20 includes a periodically alternately stacked InGaN hole injection layer 21 and an AlGaN hole injection layer 22. The AlGaN material with a low bandgap width 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 to the multi-quantum well light-emitting layer 500, and allow the quantum wells close to the N-type semiconductor layer 300 to also participate in light emission.

[0025] In addition to inserting a hole injection layer 20 into the GaN quantum barrier layer of the fourth sublayer 540, an electron injection layer 10 is inserted into the GaN quantum barrier layer of at least one of the first sublayer 510, the second sublayer 520, and the third sublayer 530. 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 GaN electron injection layer 12 can provide electrons, and the first AlGaN protective layer 11 and the second AlGaN protective layer 13 can block electrons and reduce the electron mobility, thereby preventing electrons from overflowing to the P-type semiconductor layer 700 to cause electron leakage. The multi-quantum well light-emitting layer 500 structure provided by the present invention can significantly improve the matching degree of the electron-hole concentration in the light-emitting quantum well region, thereby improving the brightness and light efficiency of the LED device.

[0026] It is understandable that if Figure 2~Figure 6 As shown, the first sublayer 510 includes a first InGaN quantum well layer 511 and a first GaN quantum barrier layer 512 that are periodically alternately stacked, the second sublayer 520 includes a second InGaN quantum well layer 521 and a second GaN quantum barrier layer 522 that are periodically alternately stacked, the third sublayer 530 includes a third InGaN quantum well layer 531 and a third GaN quantum barrier layer 532 that are periodically alternately stacked, and the fourth sublayer 540 includes a fourth InGaN quantum well layer 541 and a fourth GaN quantum barrier layer 542 that are periodically alternately stacked. 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 is inserted with an electron injection layer 10, and the fourth GaN quantum barrier layer 542 is inserted with a hole injection layer 20.

[0027] Specifically, Figure 3~Figure 5 As 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.

[0028] 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.

[0029] 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.

[0030] 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 to this, the thickness is 1nm~8nm, and exemplarily 2nm, 3nm, 5nm, 6nm or 7nm, but not limited to this. The Al component ratio of the second AlGaN protective layer 13 is 0.01~0.3, and exemplarily 0.05, 0.1, 0.15, 0.2 or 0.25, but not limited to this, and the thickness is 0.5nm~2nm, and exemplarily 0.8nm, 1nm, 1.2nm, 1.5nm or 1.8nm, but not limited to this. The GaN electron injection layer 12 is used to provide electrons, and the first AlGaN protective layer 11 and the second AlGaN protective layer 13 are used to protect the GaN electron injection layer 12 to prevent electron overflow from occurring in the GaN electron injection layer 12 and being injected into the P-type semiconductor layer 700 to cause electron leakage.

[0031] More preferably, the electron injection layer 10 is inserted into the GaN quantum barrier layers of the first sublayer 510, the second sublayer 520, and the third sublayer 530. In each sublayer, 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 sublayer 510 to the third sublayer 530, the Al component ratio of the first AlGaN protective layer 11 decreases, wherein the Al component ratio of the first AlGaN protective layer 11 and the second AlGaN protective layer 13 of the first sublayer 510 and the second sublayer 520 is relatively high, and the quantum barrier layer of the high Al component material has a high bandgap width, which can bind electrons in front of the first GaN quantum barrier layer 512 and the second GaN quantum barrier layer 522, play a role in blocking electrons and reducing the electron mobility, effectively prevent electron overflow, and even inject 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 sublayer 510 to the third sublayer 530 , the Si doping concentration of the GaN electron injection layer 12 decreases, which improves the matching degree of the electron-hole concentration in the light-emitting quantum well region and further avoids electron leakage caused by electron injection into the P-type semiconductor layer 700 .

[0032] In one embodiment, in the electron injection layer 10 of the first sublayer 510, the Al component ratio of the first AlGaN protective layer 11 is 0.05-0.3, exemplarily 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 , exemplarily 5×10 17 cm -3 , 5.5×10 17 cm -3 , 6×10 17 cm -3 ,7×10 17 cm -3 or 8×10 17 cm -3 , but not limited thereto; the Al component ratio of the second AlGaN protective layer 13 is 0.05~0.3, and exemplarily is 0.08, 0.1, 0.15, 0.2 or 0.25, but not limited thereto.

[0033] In the electron injection layer 10 of the second sublayer 520, the Al component ratio of the first AlGaN protective layer 11 is 0.03-0.23, exemplarily 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 , 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 Al component ratio of the second AlGaN protective layer 13 is 0.03~0.23, and exemplarily is 0.05, 0.08, 0.1, 0.15 or 0.2, but not limited thereto.

[0034] In the electron injection layer 10 of the third sublayer 530, the Al component ratio of the first AlGaN protective layer 11 is 0.01-0.15, exemplarily 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 , an exemplary value is 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 component ratio of the second AlGaN protective layer 13 is 0.01~0.15, and exemplarily is 0.02, 0.04, 0.06, 0.08 or 0.1, but not limited thereto.

[0035] Specifically, Figure 6 As 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 sublayer 540 includes a fourth InGaN quantum well layer 541, a fourth GaN quantum barrier first sublayer 542a, a hole injection layer 20 and a fourth GaN quantum barrier second sublayer 542b stacked in sequence. The growth conditions of the fourth GaN quantum barrier first sublayer 542a and the fourth GaN quantum barrier second sublayer 542b are the same, and the thicknesses may be the same or different.

[0036] The hole injection layer 20 includes an InGaN hole injection layer 21 and an AlGaN hole injection layer 22 that are periodically alternately stacked. The number of cycles of the hole injection layer 20 alternately stacked is 2 to 5, and is 3 or 4 for example. The InGaN hole injection layer 21 is a Mg-doped InGaN hole injection layer, and the In component ratio is 0.01 to 0.08, and is 0.02, 0.03, 0.05, 0.06 or 0.07 for example, but not limited thereto. The Mg doping concentration is 2.5×10 18 cm -3 ~6.2×10 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, the thickness is 0.5nm~2nm, exemplarily 0.8nm, 1nm, 1.2nm, 1.5nm or 1.8nm, but not limited thereto. The Al component ratio of the AlGaN hole injection layer 22 is 0.01~0.08, exemplarily 0.02, 0.03, 0.05, 0.06 or 0.07, but not limited thereto, the thickness is 0.5nm~2nm, exemplarily 0.8nm, 1nm, 1.2nm, 1.5nm or 1.8nm, but not limited thereto. The InGaN hole injection layer 21 is a Mg-doped InGaN hole injection layer, which can provide part of the holes to the light-emitting quantum well region to participate in the radiation recombination luminescence, so as to improve the matching degree of the electron-hole concentration in the light-emitting quantum well region. The Al component ratio of the AlGaN hole injection layer 22 is low, which can reduce the blocking effect of the fourth sublayer 540 on hole injection.

[0037] like Figure 7As shown, in a preferred embodiment, the number of cycles of the alternating stacking of the fourth sublayer 540 is 2. Specifically, in the first cycle, the In component ratio of the fourth InGaN quantum well layer 541A is 0.07-0.38, and is exemplarily 0.1, 0.15, 0.2, 0.3 or 0.35, but not limited thereto, and the thickness is 2.1nm-4.5nm, and is exemplarily 2.5nm, 3nm, 3.2nm, 3.6nm or 4nm, but not limited thereto, and the thickness of the fourth GaN quantum barrier layer 542A is 6nm-15nm, and is exemplarily 8nm, 9nm, 10nm, 12nm or 14nm, but not limited thereto. In the second period, the fourth InGaN quantum well layer 541B is a Mg-doped InGaN quantum well layer, the In component ratio is 0.07-0.38, 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, the thickness is 2.1nm~4.5nm, exemplarily 2.5nm, 3nm, 3.2nm, 3.6nm or 4nm, but not limited thereto, the thickness of the fourth GaN quantum barrier layer 542B is 6nm~15nm, exemplarily 8nm, 9nm, 10nm, 12nm or 14nm, but not limited thereto. In the fourth sublayer 540, the fourth InGaN quantum well layer 541A of the first period is not intentionally doped, and the fourth InGaN quantum well layer 541B of the second period is doped with low concentration of Mg, which can provide a certain amount of holes while ensuring the luminous efficiency of the multi-quantum well light-emitting area close to the P-type semiconductor layer 700, and the holes move to the side of the N-type semiconductor 300, thereby improving the matching degree of the hole-electron concentration in the multi-quantum well light-emitting layer 500.

[0038] 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.

[0039] 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 -3From the first sublayer 510 to the third sublayer 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 gradually, thereby preventing electron leakage caused by electron injection into the P-type semiconductor layer 700 .

[0040] In addition to the multi-quantum well light-emitting layer 500, other layered structures of the present invention have the following characteristics: The substrate 100 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. In one embodiment, the substrate 100 is a sapphire substrate.

[0041] The buffer layer 200 may 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.

[0042] 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 .

[0043] The low temperature stress release layer 400 may include an InGaN stress release layer and a GaN stress release layer that are periodically and alternately stacked, and the number of cycles of alternating growth is 2 to 10. The thickness of the InGaN stress release layer is 1 nm to 3 nm, and the thickness of the GaN stress release layer is 15 nm to 30 nm. The growth temperature of the low temperature stress release layer 400 is 800° C. to 900° C.

[0044] The electron blocking layer 600 may 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.

[0045] The P-type semiconductor layer 700 may be a P-type GaN layer with a thickness of 10 nm to 50 nm and a Mg doping concentration of 1×10 19 cm -3 ~5×10 20 cm -3 .

[0046] Correspondingly, such as Figure 8 As shown, the present invention also provides a method for preparing a light-emitting diode epitaxial wafer, which is used to prepare the above-mentioned light-emitting diode epitaxial wafer, comprising the following steps: S1. Provide a substrate 100.

[0047] S2 , sequentially growing 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 .

[0048] Specifically, the multi-quantum well light-emitting layer 500 includes a first sublayer 510, a second sublayer 520, a third sublayer 530 and a fourth sublayer 540 which are stacked in sequence.

[0049] In one embodiment, the preparation of the first sublayer 510 includes the following steps: controlling the growth temperature to 668°C~913°C, the growth pressure to 30torr~350torr, introducing In source, Ga source and N source, and growing the first InGaN quantum well layer 511; controlling the growth temperature to 815°C~935°C, the growth pressure to 30torr~350torr, introducing Ga source and N source, and growing the first GaN quantum barrier layer 512; repeating the periodic growth of the first InGaN quantum well layer 511 and the first GaN quantum barrier layer 512 by stacking.

[0050] In a preferred embodiment, the growth of the first sub-layer 510 in each cycle includes the following steps: The growth temperature is controlled to be 668°C to 913°C, the growth pressure is 30torr to 350torr, and In source, Ga source and N source are introduced to grow the first InGaN quantum well layer 511; the growth temperature is controlled to be 815°C to 920°C, the growth pressure is 30torr to 350torr, and Ga source, N source and Si source are introduced to grow the first GaN quantum barrier first sublayer 512a; the growth temperature is controlled to be 815°C to 920°C, the growth pressure is 30torr to 350torr, and Al source, Ga source and N source are introduced to grow the first AlGaN protective layer 1 1; control the growth temperature to 850°C~935°C, the growth pressure to 30torr~350torr, introduce Ga source, N source and Si source, and grow a GaN electron injection layer 12; control the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introduce Al source, Ga source and N source, and grow a second AlGaN protective layer 13; control the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introduce Ga source, N source and Si source, and grow the first GaN quantum barrier second sublayer 512b.

[0051] In one embodiment, the preparation of the second sublayer 520 includes the following steps: controlling the growth temperature to 668°C~913°C, the growth pressure to 30torr~350torr, introducing In source, Ga source and N source, and growing a second InGaN quantum well layer 521; controlling the growth temperature to 815°C~935°C, the growth pressure to 30torr~350torr, introducing Ga source and N source, and growing a second GaN quantum barrier layer 522; repeating the stacking periodic growth of the second InGaN quantum well layer 521 and the second GaN quantum barrier layer 522.

[0052] In a preferred embodiment, the growth of the second sub-layer 520 in each cycle includes the following steps: The growth temperature is controlled to be 668°C to 913°C, the growth pressure is 30torr to 350torr, and In source, Ga source and N source are introduced to grow the second InGaN quantum well layer 521; the growth temperature is controlled to be 815°C to 920°C, the growth pressure is 30torr to 350torr, and Ga source, N source and Si source are introduced to grow the first sublayer 522a of the second GaN quantum barrier; the growth temperature is controlled to be 815°C to 920°C, the growth pressure is 30torr to 350torr, and Al source, Ga source and N source are introduced to grow the first AlGaN protective layer 1 1; control the growth temperature to 850°C~935°C, the growth pressure to 30torr~350torr, introduce Ga source, N source and Si source, and grow a GaN electron injection layer 12; control the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introduce Al source, Ga source and N source, and grow a second AlGaN protective layer 13; control the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introduce Ga source, N source and Si source, and grow a second GaN quantum barrier second sublayer 522b.

[0053] In one embodiment, the preparation of the third sublayer 530 includes the following steps: controlling the growth temperature to 668°C~913°C, the growth pressure to 30torr~350torr, introducing In source, Ga source and N source, and growing a third InGaN quantum well layer 531; controlling the growth temperature to 815°C~935°C, the growth pressure to 30torr~350torr, introducing Ga source and N source, and growing a third GaN quantum barrier layer 532; repeating the stacking periodically to grow the third InGaN quantum well layer 531 and the third GaN quantum barrier layer 532.

[0054] In a preferred embodiment, the growth of the third sub-layer 530 in each cycle includes the following steps: The growth temperature is controlled to be 668°C to 913°C, the growth pressure is 30torr to 350torr, and In source, Ga source and N source are introduced to grow the third InGaN quantum well layer 531; the growth temperature is controlled to be 815°C to 920°C, the growth pressure is 30torr to 350torr, and Ga source, N source and Si source are introduced to grow the first sublayer 532a of the third GaN quantum barrier; the growth temperature is controlled to be 815°C to 920°C, the growth pressure is 30torr to 350torr, and Al source, Ga source and N source are introduced to grow the first AlGaN protective layer 1 1; control the growth temperature to 850°C~935°C, the growth pressure to 30torr~350torr, introduce Ga source, N source and Si source, and grow a GaN electron injection layer 12; control the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introduce Al source, Ga source and N source, and grow a second AlGaN protective layer 13; control the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introduce Ga source, N source and Si source, and grow the third GaN quantum barrier second sublayer 532b.

[0055] In one embodiment, the preparation of the fourth sublayer 540 includes the following steps: controlling the growth temperature to 668°C~913°C, the growth pressure to 30torr~350torr, introducing In source, Ga source and N source, and growing a fourth InGaN quantum well layer 541; controlling the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introducing Ga source and N source, and growing a fourth GaN quantum barrier layer 542; repeating the stacking periodically to grow the fourth InGaN quantum well layer 541 and the fourth GaN quantum barrier layer 542.

[0056] In a preferred embodiment, the growth of the fourth sublayer 540 in each cycle includes the following steps: The growth temperature is controlled to be 668°C to 913°C, the growth pressure is 30torr to 350torr, and the In source, Ga source and N source are introduced to grow the fourth InGaN quantum well layer 541; the growth temperature is controlled to be 815°C to 920°C, the growth pressure is 30torr to 350torr, and the Ga source and N source are introduced to grow the first sublayer 542a of the fourth GaN quantum barrier; the growth temperature is controlled to be 815°C to 920°C, the growth pressure is 30torr to 350torr, and the In source, Ga source, N source and M source are introduced g source, grow InGaN hole injection layer 21; control the growth temperature to 815℃~920℃, the growth pressure to 30torr~350torr, introduce Al source, Ga source and N source, and grow AlGaN hole injection layer 22; repeat the stacking periodic growth of InGaN hole injection layer 21 and AlGaN hole injection layer 22; control the growth temperature to 815℃~920℃, the growth pressure to 30torr~350torr, introduce Ga source and N source, and grow the second sublayer 542b of the fourth GaN quantum barrier.

[0057] More preferably, the preparation of the fourth sublayer 540 includes the following steps: controlling the growth temperature to 668°C~913°C, the growth pressure to 30torr~350torr, introducing In source, Ga source and N source, and growing a fourth InGaN quantum well layer 541A; controlling the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introducing Ga source and N source, growing a fourth GaN quantum barrier layer 542A, and completing the first cycle of growth; controlling the growth temperature to 668°C~913°C, the growth pressure to 30torr~350torr, introducing In source, Ga source, N source and Mg source, and growing a fourth InGaN quantum well layer 541B; controlling the growth temperature to 815°C~920°C, the growth pressure to 30torr~350torr, introducing Ga source and N source, and growing a fourth GaN quantum barrier layer 542B, and completing the second cycle of growth, that is, growing for 2 cycles to obtain the fourth sublayer 540.

[0058] Correspondingly, the present invention further provides a light emitting diode, which includes the light emitting diode epitaxial wafer mentioned above.

[0059] The present invention will be further described below with specific embodiments: Example 1 This embodiment provides a light-emitting diode epitaxial wafer, including 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.

[0060] The multi-quantum well light-emitting layer includes a first sublayer, a second sublayer, a third sublayer and a fourth sublayer which are stacked in sequence.

[0061] The first sublayer includes a first InGaN quantum well layer and a first GaN quantum barrier layer that are periodically and alternately stacked. The number of cycles of the alternating stacking is 3. The In component ratio of the first InGaN quantum well layer is 0.2, and the thickness is 3nm. 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 , with a thickness of 12nm. An electron injection layer is also inserted into the first GaN quantum barrier layer, which includes a first AlGaN protective layer, a GaN electron injection layer, and a second AlGaN protective layer stacked in sequence. The Al component ratio of the first AlGaN protective layer is 0.15, and the thickness is 1.5nm. The GaN electron injection layer is a Si-doped GaN electron injection layer with a Si doping concentration of 5×10 17 cm -3 , with a thickness of 5nm, the Al component ratio of the second AlGaN protective layer is 0.15, and the thickness is 1.5nm.

[0062] The second sublayer includes a second InGaN quantum well layer and a second GaN quantum barrier layer that are periodically and alternately stacked. The number of cycles of the alternating stacking is 4. The In component ratio of the second InGaN quantum well layer is 0.2, and the thickness is 3nm. 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 , with a thickness of 12nm.

[0063] The third sublayer includes a third InGaN quantum well layer and a third GaN quantum barrier layer that are periodically and alternately stacked. The number of cycles of the alternating stacking is 3. The In component ratio of the third InGaN quantum well layer is 0.2, and the thickness is 3nm. 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 , with a thickness of 12nm.

[0064] The fourth sublayer includes a fourth InGaN quantum well layer and a fourth GaN quantum barrier layer that are periodically alternately stacked, the number of alternately stacked periods is 3, the In component ratio of the fourth InGaN quantum well layer is 0.2, the thickness is 3nm, and the thickness of the fourth GaN quantum barrier layer is 12nm. A hole injection layer is also inserted in the fourth GaN quantum barrier layer, and the hole injection layer includes a periodically alternately stacked InGaN hole injection layer and an AlGaN hole injection layer, the number of alternately stacked periods is 3, the InGaN hole injection layer is a Mg-doped InGaN hole injection layer, the In component ratio is 0.05, and the Mg doping concentration is 1×10 19 cm -3, thickness is 1.5nm, the Al component ratio of the AlGaN hole injection layer is 0.05, and the thickness is 1.5nm.

[0065] Example 2 This embodiment provides a light-emitting diode epitaxial wafer, which is different from the embodiment 1 in that the number of cycles of the fourth sublayer alternately stacked is 2, wherein the fourth InGaN quantum well layer of the first cycle has an In component ratio of 0.2 and a thickness of 3 nm, and the thickness of the fourth GaN quantum barrier layer is 12 nm, and the fourth InGaN quantum well layer of the second cycle is a Mg-doped InGaN quantum well layer, with an In component ratio of 0.2 and a Mg doping concentration of 7.5×10 18 cm -3 , with a thickness of 3nm, and the thickness of the fourth GaN quantum barrier layer is 12nm.

[0066] The rest are the same as in Example 1.

[0067] Example 3 This embodiment provides a light-emitting diode epitaxial wafer, which is different from the embodiment 2 in that an electron injection layer is inserted into the first GaN quantum barrier layer, the second GaN quantum barrier layer, and the third GaN quantum barrier layer. The electron injection layers in the first GaN quantum barrier layer, the second GaN quantum barrier layer, and the third GaN quantum barrier layer have the same structure, and all include a first AlGaN protective layer, a GaN electron injection layer, and a second AlGaN protective layer stacked in sequence. The Al component 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 , with a thickness of 5nm, the Al component ratio of the second AlGaN protective layer is 0.15, and the thickness is 1.5nm.

[0068] The rest are the same as in Example 2.

[0069] Example 4 This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 3 in that, in the electron injection layer of the first GaN quantum barrier layer, the Al component proportion of the first AlGaN protective layer is 0.25, and the Al component proportion of the second AlGaN protective layer is 0.25; in the electron injection layer of the second GaN quantum barrier layer, the Al component proportion of the first AlGaN protective layer is 0.15, and the Al component proportion of the second AlGaN protective layer is 0.15; in the electron injection layer of the third GaN quantum barrier layer, the Al component proportion of the first AlGaN protective layer is 0.05, and the Al component proportion of the second AlGaN protective layer is 0.05.

[0070] The rest is the same as Example 3.

[0071] Example 5 This embodiment provides a light emitting diode epitaxial wafer, which is different from the embodiment 4 in that the Si doping concentration of the electron injection layer of the first GaN quantum barrier 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 .

[0072] The rest is the same as Example 4.

[0073] Comparative Example 1 This comparative example provides a light-emitting diode epitaxial wafer, which is different from Example 1 in that the multi-quantum well light-emitting layer includes periodically alternately stacked InGaN quantum well layers and AlGaN quantum barrier layers, and the number of alternately stacked periods is 12. Among them, the In component in the InGaN quantum well layer accounts for 0.2 and the thickness is 3nm, and the Al component in the AlGaN quantum barrier layer accounts for 0.05 and the thickness is 12nm.

[0074] The rest are the same as in Example 1.

[0075] Comparative Example 2 This comparative example provides a light-emitting diode epitaxial wafer, which is different from Example 1 in that in the multi-quantum well light-emitting layer, no hole injection layer is inserted into the fourth GaN quantum barrier layer of the fourth sublayer.

[0076] The rest are the same as in Example 1.

[0077] Comparative Example 3 This comparative example provides a light-emitting diode epitaxial wafer, which is different from Example 1 in that in the multi-quantum well light-emitting layer, no electron injection layer is inserted into the first GaN quantum barrier layer of the first sublayer.

[0078] The rest are the same as in Example 1.

[0079] The light-emitting diode epitaxial wafers obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were made into 15mil×15mil LED chips, and their luminous efficiency was tested at a current of 120mA / 60mA on the same LED spot tester. The luminous efficiency improvement of Examples 1 to 5, Comparative Examples 2 and 3 compared with Comparative Example 1 was calculated, and the test results are shown in the following table.

[0080]

[0081] It can be seen from the above table that the light-emitting diode epitaxial wafer provided by the embodiment of the present invention can effectively improve the light-emitting efficiency of the chip.

[0082] The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. 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: 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 InGaN quantum well layers and GaN quantum barrier layers stacked alternately and periodically; 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.

2. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The number of cycles 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 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 , with a thickness of 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: The number of cycles of the fourth sublayer being alternately stacked is 2; in the first cycle, 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 cycle, 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 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 , with a thickness of 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 4, characterized in that: An electron injection layer is inserted into the GaN quantum barrier layers of the first sublayer, the second sublayer and the third sublayer; 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 sub-layer to the third sub-layer, the Al component ratio of the first AlGaN protective layer decreases; from the first sub-layer to the third sub-layer, the Si doping concentration of the GaN electron injection layer decreases.

6. The light emitting diode epitaxial wafer according to claim 5, 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.

7. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The number of cycles of the alternating stacking of the first sublayer is 2-4, the number of cycles of the alternating stacking of the second sublayer is 2-6, and the number of cycles of the alternating stacking of the third sublayer is 2-5; 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.

8. 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 7, 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.

9. The method for preparing a light emitting diode epitaxial wafer according to claim 8, 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.

10. 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 7.

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