Light emitting diode epitaxial wafer and preparation method thereof

Abstract

The invention discloses a light-emitting diode epitaxial wafer and a preparation method thereof, and relates to the technical field of semiconductors. The light-emitting diode epitaxial wafer comprises a substrate, and a buffer layer, a non-doped GaN layer, an N-type GaN layer, an electron dredging layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer which are stacked on the substrate in sequence, the electron dredging layer comprises a first sub-layer, a second sub-layer, a third sub-layer and a fourth sub-layer which are sequentially stacked, the first sub-layer is a Si3N4 layer, the second sub-layer comprises an AlGaN layer, a first InGaN layer and a first GaN layer which are periodically and alternately stacked, the third sub-layer comprises a second GaN layer and a second InGaN layer which are periodically and alternately stacked, and the fourth sub-layer is a Si3N4 layer. And the fourth sub-layer comprises an AlInGaN layer, a third InGaN layer and a third GaN layer which are periodically and alternately stacked. According to the invention, while the electronic expansibility is improved, excessive electrons are prevented from entering the multi-quantum well layer to generate electron overflow.

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. Background Art

[0002] III-V nitride materials, represented by GaN, have been extensively researched, developed, and applied over the past decade. High-efficiency GaN-based light-emitting diodes (LEDs), with their notable advantages of long life, energy efficiency, and environmental friendliness, have been widely used in lighting, large-screen displays, traffic signals, multimedia displays, and optical communications. However, the luminous efficiency of GaN-based LEDs is affected by numerous factors, resulting in low luminous efficiency and severely restricting their commercial application as high-brightness, high-power devices in lighting. P-type doping of GaN materials is relatively difficult, and the P-type doping concentration is much lower than the N-type doping concentration. Furthermore, the effective mass of holes is much greater than that of electrons, resulting in a much lower hole mobility than that of electrons. These two factors result in a much lower hole injection rate than that of electrons into the multi-quantum well region, leading to a mismatch between electron and hole injection and ultimately affecting 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 electronic extensibility while preventing excessive electrons from entering the multi-quantum well layer and causing electron overflow.

[0004] 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 undoped GaN layer, an N-type GaN layer, an electron dredging layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer sequentially stacked on the substrate; The electron pass layer includes a first sublayer, a second sublayer, a third sublayer and a fourth sublayer stacked in sequence, the first sublayer is a Si3N4 layer, the second sublayer includes a periodically alternately stacked AlGaN layer, a first InGaN layer and a first GaN layer, the third sublayer includes a periodically alternately stacked second GaN layer and a second InGaN layer, and the fourth sublayer includes a periodically alternately stacked AlInGaN layer, a third InGaN layer and a third GaN layer.

[0005] As an improvement of the above technical solution, the thickness of the Si3N4 layer is 1nm~10nm.

[0006] As an improvement to the above technical solution, the number of cycles of the alternating stacking of the second sub-layer is 3 to 8; the AlGaN layer is a Ga-polar AlGaN layer, the Al component ratio is 0.01 to 0.2, and the thickness is 1 nm to 10 nm; the In component ratio of the first InGaN layer is 0.01 to 0.1, and the thickness is 1 nm to 10 nm; the first GaN layer is a Si-doped GaN layer, and the Si doping concentration is 1×10 18 cm -3 ~1×10 19 cm -3 , thickness is 5nm~20nm.

[0007] As an improvement of the above technical solution, as the number of alternating stacking periods increases, the Al component ratio of the AlGaN layer increases, and the Si doping concentration of the first GaN layer increases.

[0008] As an improvement to the above technical solution, the number of cycles of the alternating stacking of the third sub-layer is 5 to 20; the second GaN layer is an N-polarity Si-doped GaN layer, and the Si doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 , with a thickness of 5nm~10nm; the In component ratio of the second InGaN layer is 0.01~0.1, and the thickness is 1nm~10nm.

[0009] As an improvement to the above technical solution, the number of cycles of the alternating stacking of the fourth sublayer is 5 to 20; the AlInGaN layer is a Ga-polar AlInGaN layer, the Al component ratio is 0.01 to 0.2, the In component ratio is 0.01 to 0.1, and the thickness is 1 nm to 10 nm; the In component ratio of the third InGaN layer is 0.01 to 0.1, and the thickness is 1 nm to 10 nm; the third GaN layer is a Si-doped GaN layer, and the Si doping concentration is 1×10 18 cm -3 ~1×10 19 cm -3 , thickness is 5nm~20nm.

[0010] As an improvement of the above technical solution, as the number of alternating stacking periods increases, the Al component ratio of the AlInGaN layer decreases, the In component ratio of the AlInGaN layer increases, and the Si doping concentration of the third GaN layer decreases.

[0011] Correspondingly, the present invention also discloses a method for preparing the above-mentioned light-emitting diode epitaxial wafer, comprising the following steps: Providing a substrate, and sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, an electron dredging layer, a multi-quantum well layer, an electron blocking layer, and a P-type GaN layer on the substrate; The electron pass layer includes a first sublayer, a second sublayer, a third sublayer and a fourth sublayer stacked in sequence, the first sublayer is a Si3N4 layer, the second sublayer includes a periodically alternately stacked AlGaN layer, a first InGaN layer and a first GaN layer, the third sublayer includes a periodically alternately stacked second GaN layer and a second InGaN layer, and the fourth sublayer includes a periodically alternately stacked AlInGaN layer, a third InGaN layer and a third GaN layer.

[0012] As an improvement of the above technical solution, the growth temperature of the second sub-layer is 800° C. to 900° C., the growth pressure is 50 torr to 500 torr, and the growth atmosphere is H2; The growth temperature of the third sub-layer is 800° C. to 900° C., the growth pressure is 50 torr to 500 torr, and the growth atmosphere is N2; The growth temperature of the fourth sub-layer is 800° C. to 900° C., the growth pressure is 50 torr to 500 torr, and the growth atmosphere is H 2 .

[0013] As an improvement to the above technical solution, after the growth of the first InGaN layer and the third InGaN layer is completed, a mixed gas is introduced for treatment, wherein the mixed gas includes N2, H2 and NH3, with a volume ratio of 1:1:1 to 1:20:10, and the introduction time is 5s to 15s.

[0014] The implementation of the present invention has the following beneficial effects: The light-emitting diode epitaxial wafer provided by the present invention includes an electron dredging layer disposed between an N-type GaN layer and a multi-quantum well layer. The electron dredging layer comprises a first sublayer, a second sublayer, a third sublayer, and a fourth sublayer stacked in sequence. The first sublayer is a Si3N4 layer, which can change the extension direction of underlying line defects, causing them to converge and annihilate, thereby reducing the number of dislocations. The second, third, and fourth sublayers all have a superlattice structure, which can continuously annihilate dislocations at the interface. Materials such as AlGaN, InGaN, and AlInGaN can improve electron expansion efficiency while preventing excessive electrons from entering the multi-quantum well layer and causing electron overflow, ultimately improving the luminous efficiency of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a schematic structural diagram of a light-emitting diode epitaxial wafer provided in an embodiment of the present invention; Figure 2 Schematic diagram of the structure of the electron dredging layer provided by an embodiment of the present invention; Figure 3It is a schematic flow chart of a method for preparing a light-emitting diode epitaxial wafer provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0017] like Figure 1 As shown, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate 100, and a buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, an electron-passing layer 500, a multi-quantum well layer 600, an electron blocking layer 700 and a P-type GaN layer 800 sequentially stacked on the substrate 100.

[0018] Among them, Figure 2 As shown, the electron pass layer 500 includes a first sublayer 510, a second sublayer 520, a third sublayer 530 and a fourth sublayer 540 stacked in sequence, the first sublayer 510 is a Si3N4 layer, the second sublayer 520 includes a periodically alternately stacked AlGaN layer 521, a first InGaN layer 522 and a first GaN layer 523, the third sublayer 530 includes a periodically alternately stacked second GaN layer 531 and a second InGaN layer 532, the fourth sublayer 540 includes a periodically alternately stacked AlInGaN layer 541, a third InGaN layer 542 and a third GaN layer 543.

[0019] The light-emitting diode epitaxial wafer provided by the present invention includes an electron dredging layer 500 disposed between an N-type GaN layer 400 and a multi-quantum well layer 600. The electron dredging layer 500 includes a first sublayer 510, a second sublayer 520, a third sublayer 530, and a fourth sublayer 540 stacked in sequence. The first sublayer 510 is a Si3N4 layer, which can change the extension direction of the underlying line defects, causing them to converge and annihilate, thereby reducing the number of dislocations. The second sublayer 520, the third sublayer 530, and the fourth sublayer 540 are each relatively thin and have a superlattice structure, which can continuously annihilate dislocations at the interface. Materials such as AlGaN, InGaN, and AlInGaN can improve electron expansion efficiency while preventing excessive electrons from entering the multi-quantum well layer 600 and causing electron overflow, ultimately improving the luminous efficiency of the light-emitting diode.

[0020] In one embodiment, the thickness of the Si3N4 layer is 1 nm to 10 nm, exemplified by, but not limited to, 2 nm, 4 nm, 5 nm, 6 nm, 8 nm, or 9 nm. The Si3N4 layer redirects most of the underlying line defects, causing them to converge and annihilate, thereby reducing the number of dislocations.

[0021] In one embodiment, the number of cycles of alternating stacking of the second sublayer 520 is 3 to 8, and exemplary cycles are 4, 5, 6, or 7. In each growth cycle, the AlGaN layer 521 is a Ga-polar AlGaN layer, and the Al component ratio is 0.01 to 0.2, and exemplary cycles are 0.05, 0.08, 0.1, 0.12, 0.16, or 0.18, but not limited thereto. The thickness of the AlGaN layer 521 is 1 nm to 10 nm, and exemplary cycles are 2 nm, 4 nm, 5 nm, 6 nm, 8 nm, or 9 nm, but not limited thereto. The Ga-polar AlGaN layer can reduce the incorporation of oxygen impurities and improve crystal quality. In each growth cycle, the In component ratio of the first InGaN layer 522 is 0.01-0.1, and is exemplarily 0.02, 0.03, 0.04, 0.05, 0.06 or 0.08, but not limited thereto. The thickness of the first InGaN layer 522 is 1 nm-10 nm, and is exemplarily 2 nm, 4 nm, 5 nm, 6 nm, 8 nm or 9 nm, but not limited thereto. In each growth cycle, the first GaN layer 523 is a Si-doped GaN layer with a Si doping concentration of 1×10 18 cm -3 ~1×10 19 cm -3 , for example 2×10 18 cm -3 , 4×10 18 cm -3 , 5×10 18 cm -3 , 6×10 18 cm -3 , 8×10 18 cm -3 or 9×10 18 cm -3 The thickness of the first GaN layer 523 is, but is not limited to, 5 nm to 20 nm, exemplified by, but not limited to, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, or 18 nm. The compressive stress of the AlGaN layer introduced into the superlattice structure of the second sublayer 520 can effectively balance the tensile stress of the GaN layer on the substrate 100, preventing cracks in the GaN epitaxial layer due to thermal stress and tensile stress on the substrate 100, thereby improving the uniformity and crystal quality of subsequent epitaxial wafers. A small amount of Si doping in the first GaN layer 523 can reduce resistivity and lower the operating voltage.

[0022] In a preferred embodiment, as the number of alternating stacking cycles increases, the Al component ratio of the AlGaN layer 521 increases, which can gradually reduce the electron migration speed and reduce electron overflow. As the number of alternating stacking cycles increases, the Si doping concentration of the first GaN layer 523 increases, which can evenly distribute electrons on the surface, reduce current congestion effects, and improve electron expansion efficiency.

[0023] In a preferred embodiment, after the growth of the first InGaN layer 522 is completed, a mixed gas is introduced for treatment. The mixed gas includes N2, H2 and NH3, and the volume ratio is 1:1:1~1:20:10. The introduction time is 5s~15s. This can reduce the number of interface In droplets, increase the interface crystal quality, and enhance the distribution uniformity of In after incorporation.

[0024] In one embodiment, the number of cycles of the alternating stacking of the third sub-layer 530 is 5 to 20, exemplified by 6, 8, 10, 12, 14 or 18, but not limited thereto. In each growth cycle, the second GaN layer 531 is an N-polarity Si-doped GaN layer, and the Si doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 , an exemplary value is 2.5×10 19 cm -3 , 5×10 19 cm -3 , 7.5×10 19 cm -3 , 1×10 20 cm -3 , 5×10 20 cm -3 or 7.5×10 20 cm -3 , but not limited to this, the thickness of the second GaN layer 531 is 5nm~10nm, and is exemplarily 5.5nm, 6nm, 7nm, 8nm, 9nm or 9.5nm, but not limited to this. N polarity can increase the efficiency of In incorporation, form a flat and smooth two-dimensional plane as quickly as possible, improve the crystal quality of the quantum well, and enhance the luminous efficiency of the light-emitting diode. In each growth cycle, the In component ratio of the second InGaN layer 532 is 0.01~0.1, and is exemplarily 0.02, 0.03, 0.04, 0.05, 0.06 or 0.08, but not limited to this. The thickness of the second InGaN layer 532 is 1nm~10nm, and is exemplarily 2nm, 4nm, 5nm, 6nm, 8nm or 9nm, but not limited to this.

[0025] In one embodiment, the fourth sublayer 540 is alternately stacked for 5 to 20 cycles, typically 6, 8, 10, 12, 14, or 18, but not limited thereto. In each growth cycle, the AlInGaN layer 541 is a Ga-polar AlInGaN layer, with an Al component ratio of 0.01 to 0.2, typically 0.05, 0.08, 0.1, 0.12, 0.16, or 0.18, but not limited thereto, and an In component ratio of 0.01 to 0.1, typically 0.02, 0.03, 0.04, 0.05, 0.06, or 0.08, but not limited thereto. The thickness of the AlInGaN layer 541 is 1 nm to 10 nm, typically 2 nm, 4 nm, 5 nm, 6 nm, 8 nm, or 9 nm, but not limited thereto. The Ga-polar AlInGaN layer has a downward spontaneous polarization field, which, when superimposed with the piezoelectric polarization field, can further regulate the direction of the energy band bending, prevent excessive electron injection, and reduce the probability of non-radiative recombination in the multi-quantum well layer 600. In each growth cycle, the In component ratio of the third InGaN layer 542 is 0.01~0.1, and is exemplarily 0.02, 0.03, 0.04, 0.05, 0.06 or 0.08, but not limited thereto. The thickness of the third InGaN layer 542 is 1nm~10nm, and is exemplarily 2nm, 4nm, 5nm, 6nm, 8nm or 9nm, but not limited thereto. In each growth cycle, the third GaN layer 543 is a Si-doped GaN layer with a Si doping concentration of 1×10 18 cm -3 ~1×10 19 cm -3 , for example 2×10 18 cm -3 , 4×10 18 cm -3 , 5×10 18 cm -3 , 6×10 18 cm -3 , 8×10 18 cm -3 or 9×10 18 cm -3 , but not limited thereto, the thickness of the third GaN layer 543 is 5 nm to 20 nm, and exemplarily is 8 nm, 10 nm, 12 nm, 14 nm, 16 nm or 18 nm, but not limited thereto.

[0026] In a preferred embodiment, as the number of alternating stacking cycles increases, the Al content of the AlInGaN layer 541 decreases, while the In content of the AlInGaN layer 541 increases, effectively constructing a conduction band tilt barrier, significantly reducing electron overflow, and improving device efficiency and reliability. As the number of alternating stacking cycles increases, the Si doping concentration of the third GaN layer 543 decreases, improving electron extensibility while also preventing excessive electrons from rushing into the quantum well and causing electron overflow. More preferably, as the number of alternating stacking cycles increases, the In content of the third InGaN layer 542 decreases.

[0027] In a preferred embodiment, after the growth of the third InGaN layer 542 is completed, a mixed gas is introduced for treatment. The mixed gas includes N2, H2 and NH3, and the volume ratio is 1:1:1~1:20:10. The introduction time is 5s~15s. This can reduce the number of interface In droplets, increase the interface crystal quality, and enhance the distribution uniformity of In after incorporation.

[0028] In addition to the electron-passing layer 500, other characteristics of the layered structure of the present invention are as follows: 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, substrate 100 is a sapphire substrate. Sapphire is currently the most commonly used substrate material for GaN-based light-emitting diodes. Sapphire substrates have advantages such as mature preparation technology, low cost, easy cleaning and handling, and good stability at high temperatures.

[0029] The buffer layer 200 can be one or more of an AlN buffer layer, a GaN buffer layer, and an AlGaN buffer layer. In one embodiment, the buffer layer 200 is an AlN buffer layer with a thickness of 10 nm to 50 nm. The AlN buffer layer provides nucleation centers with the same orientation as the substrate 100, relieving the stress generated by the lattice mismatch between the GaN and the substrate 100 and the thermal stress generated by the mismatch in thermal expansion coefficients. It provides a flat nucleation surface for further growth, reduces the contact angle of its nucleation growth, and enables the island-like growth of GaN grains to connect into a surface within a smaller thickness, transforming to two-dimensional epitaxial growth.

[0030] The thickness of the undoped GaN layer 300 is 1 μm to 5 μm. As the thickness of the undoped GaN layer 300 increases, compressive stress is released through stacking faults, line defects are reduced, crystal quality is improved, and reverse leakage is reduced. However, increasing the thickness of the undoped GaN layer 300 consumes a large amount of Ga source material, greatly increasing the epitaxial cost of the LED. Therefore, the thickness of the undoped GaN layer 300 is preferably 2 μm to 3 μm, which not only saves production costs but also improves the crystal quality of the undoped GaN layer 300.

[0031] The N-type GaN layer 400 is a Si-doped GaN layer with a Si doping concentration of 1×10 19 cm -3 ~5×10 19 cm -3 , with a thickness of 2μm to 3μm. The N-type GaN layer 400 provides sufficient electrons for the light-emitting diode to emit light. Secondly, the resistivity of the N-type GaN layer 400 is higher than that of the transparent electrode on the P-type GaN layer 800. Therefore, sufficient Si doping can effectively reduce the resistivity of the N-type GaN layer 400. In addition, a sufficiently thick N-type GaN layer 400 can effectively relieve stress and improve the luminous efficiency of the light-emitting diode.

[0032] The multi-quantum well layer 600 comprises a periodic alternating stack of InGaN quantum well layers and AlGaN quantum barrier layers, with a growth period of 6 to 12. Within each period, the InGaN quantum well layer has a thickness of 2nm to 5nm, while the AlGaN quantum barrier layer has an Al content of 0.01 to 0.1 and a thickness of 5nm to 15nm. The multi-quantum well layer 600 is the region where electrons and holes recombine. A rational structural design can significantly increase the overlap of electron and hole wave functions, thereby improving the luminous efficiency of the LED device.

[0033] The electron blocking layer 700 may be an AlInGaN electron blocking layer, with an Al component ratio of 0.01-0.1, an In component ratio of 0.01-0.2, and a thickness of 10 nm-40 nm.

[0034] The P-type GaN layer 800 is a Mg-doped GaN layer with a Mg doping concentration of 1×10 19 cm -3 ~1×10 21 cm -3 , thickness is 10nm~50nm.

[0035] Correspondingly, such as Figure 3 As shown, the present invention also discloses a method for preparing the above-mentioned light-emitting diode epitaxial wafer, comprising the following steps: S1. Provide a substrate.

[0036] In one embodiment, the substrate is a sapphire substrate.

[0037] S2, sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, an electron-passing layer, a multi-quantum well layer, an electron-blocking layer, and a P-type GaN layer on the substrate. It is understood that each layered structure can be grown by MOCVD, MBE, PVD, or VPE, but is not limited thereto. Specifically, S2 includes the following steps: S21. Grow a buffer layer.

[0038] An AlN buffer layer is grown using PVD. In one embodiment, a sapphire substrate coated with an AlN buffer layer is placed in an MOCVD process and pretreated in an H2 atmosphere for 1 to 10 minutes at a temperature of 1000°C to 1200°C. This improves the crystal quality of the AlN buffer layer and the subsequent GaN epitaxial layer.

[0039] S22. Grow an undoped GaN layer.

[0040] The non-doped GaN layer is grown by MOCVD, the temperature of the reaction chamber is controlled to be 1050℃~1200℃, the pressure is 100torr~600torr, and N source and Ga source are introduced.

[0041] S23 , growing an N-type GaN layer.

[0042] The N-type GaN layer is grown by MOCVD, the temperature of the reaction chamber is controlled to be 1050℃~1200℃, the pressure is 100torr~600torr, and N source, Ga source and N-type doping source are introduced.

[0043] S24, growing an electron-passing layer.

[0044] MOCVD and / or PECVD are used to sequentially grow the first sublayer, the second sublayer, the third sublayer, and the fourth sublayer. Specifically, S24 includes the following steps: S241 , growing a first sublayer.

[0045] The first sublayer is grown by PECVD, the temperature of the reaction chamber is controlled at 200℃~400℃, the pressure is 0.5torr~5torr, radio frequency or microwave excitation is used, silane (SiH4) or silicon tetrafluoride (SiF4) is introduced as the Si source, and ammonia (NH3) or nitrogen (N2) is introduced as the N source.

[0046] S242 , growing a second sublayer.

[0047] The second sublayer is grown by MOCVD, the temperature of the reaction chamber is controlled to be 800℃~900℃, the pressure is 50torr~500torr, the growth atmosphere is H2, N source, Ga source and Al source are introduced to grow the AlGaN layer, N source, Ga source and In source are introduced to grow the first InGaN layer, N source and Ga source are introduced to grow the first GaN layer, and the AlGaN layer, the first InGaN layer and the first GaN layer are repeatedly stacked to grow periodically.

[0048] In a preferred embodiment, an N source, a Ga source and an N-type doping source are introduced to grow the first GaN layer.

[0049] In a preferred embodiment, after the growth of the first InGaN layer is completed, a mixed gas is introduced for treatment, wherein the mixed gas includes N2, H2 and NH3 in a volume ratio of 1:1:1 to 1:20:10, and the introduction time is 5s to 15s.

[0050] S243. Grow the third sublayer.

[0051] The third sublayer is grown by MOCVD, the temperature of the reaction chamber is controlled to be 800℃~900℃, the pressure is 50torr~500torr, the growth atmosphere is N2, N source and Ga source are introduced to grow the second GaN layer, N source, Ga source and In source are introduced to grow the second InGaN layer, and the second GaN layer and the second InGaN layer are repeatedly stacked to grow periodically.

[0052] In a preferred embodiment, an N source, a Ga source and an N-type doping source are introduced to grow the second GaN layer.

[0053] S244, growing the fourth sublayer.

[0054] The fourth sublayer is grown by MOCVD, the temperature of the reaction chamber is controlled to be 800℃~900℃, the pressure is 50torr~500torr, the growth atmosphere is H2, N source, Ga source, In source and Al source are introduced to grow an AlInGaN layer, the N source, Ga source and In source are introduced to grow a third InGaN layer, the N source and Ga source are introduced to grow a third GaN layer, and the AlInGaN layer, the third InGaN layer and the third GaN layer are repeatedly stacked to grow periodically.

[0055] In a preferred embodiment, an N source, a Ga source and an N-type doping source are introduced to grow the third GaN layer.

[0056] In a preferred embodiment, after the third InGaN layer is grown, a mixed gas is introduced for treatment, wherein the mixed gas includes N2, H2 and NH3 in a volume ratio of 1:1:1 to 1:20:10, and the introduction time is 5s to 15s.

[0057] S25. Growing a multi-quantum well layer.

[0058] MOCVD is used to grow multiple quantum well layers, and the temperature of the reaction chamber is controlled to be 790℃~810℃ and the pressure is 50torr~300torr. N source, Ga source and In source are introduced to grow InGaN quantum well layers. The temperature of the reaction chamber is controlled to be 800℃~900℃ and the pressure is 50torr~300torr. N source, Ga source and Al source are introduced to grow AlGaN quantum barrier layers. InGaN quantum well layers and AlGaN quantum barrier layers are repeatedly stacked to grow periodically.

[0059] S26. Grow an electron blocking layer.

[0060] The electron blocking layer is grown by MOCVD, the temperature of the reaction chamber is controlled to be 900℃~1000℃, the pressure is 100torr~300torr, and N source, Ga source, Al source and In source are introduced.

[0061] S27. Grow a P-type GaN layer.

[0062] The P-type GaN layer is grown by MOCVD, the temperature of the reaction chamber is controlled to be 900℃~1050℃, the pressure is 100torr~600torr, and N source, Ga source and P-type doping source are introduced.

[0063] During the MOCVD growth process, the N source may be NH3, the Ga source may be TMGa and / or TEGa, the Al source may be TMAl, the In source may be TMIn, the N-type doping source may be SiH4, and the P-type doping source may be CP2Mg, but are not limited thereto.

[0064] 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 undoped GaN layer, an N-type GaN layer, an electron-passing layer, a multi-quantum well layer, an electron blocking layer, and a P-type GaN layer stacked sequentially on the substrate.

[0065] The electron-passing layer includes a first sublayer, a second sublayer, a third sublayer and a fourth sublayer stacked in sequence.

[0066] The first sublayer is a Si3N4 layer with a thickness of 5 nm.

[0067] The second sublayer includes a periodically alternating stack of AlGaN layers, a first InGaN layer, and a first GaN layer, with the number of alternating stacking cycles being 6. In each growth cycle, the AlGaN layer is a Ga-polar AlGaN layer with an Al component ratio of 0.1 and a thickness of 5 nm. The first InGaN layer has an In component ratio of 0.05 and a thickness of 5 nm. The first GaN layer is a Si-doped GaN layer with a Si doping concentration of 5×10 18 cm -3 , with a thickness of 10nm.

[0068] The third sublayer includes a second GaN layer and a second InGaN layer that are periodically alternately stacked, and the number of cycles of the alternating stacking is 12. In each growth cycle, the second GaN layer is an N-polarity Si-doped GaN layer, and the Si doping concentration is 1×10 20 cm -3, with a thickness of 6nm, the In component ratio of the second InGaN layer is 0.05, and the thickness is 5nm.

[0069] The fourth sublayer includes a periodically alternating stack of AlInGaN layers, a third InGaN layer, and a third GaN layer, with the number of alternating stacking cycles being 12. In each growth cycle, the AlInGaN layer is a Ga-polar AlInGaN layer with an Al component ratio of 0.1 and a thickness of 5 nm. The third InGaN layer has an In component ratio of 0.05 and a thickness of 5 nm. The third GaN layer is a Si-doped GaN layer with a Si doping concentration of 5×10 18 cm -3 , with a thickness of 10nm.

[0070] A method for preparing a light-emitting diode epitaxial wafer comprises the following steps: S1. Provide a substrate.

[0071] The substrate is a sapphire substrate.

[0072] S2, sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, an electron-passing layer, a multi-quantum well layer, an electron-blocking layer, and a P-type GaN layer on the substrate. Specifically, S2 includes the following steps: S21. Grow a buffer layer.

[0073] The AlN buffer layer was grown by PVD, and the sapphire substrate coated with the AlN buffer layer was transferred to MOCVD and pretreated in H2 atmosphere for 5 minutes at a treatment temperature of 1100°C.

[0074] S22. Grow an undoped GaN layer.

[0075] The non-doped GaN layer was grown by MOCVD, the temperature of the reaction chamber was controlled to be 1100° C., the pressure was controlled to be 150 Torr, and N source and Ga source were introduced.

[0076] S23 , growing an N-type GaN layer.

[0077] The N-type GaN layer is grown by MOCVD, the temperature of the reaction chamber is controlled to be 1120° C., the pressure is 100 torr, and an N source, a Ga source and an N-type doping source are introduced.

[0078] S24, growing an electron-passing layer.

[0079] The first sublayer, the second sublayer, the third sublayer and the fourth sublayer are grown in sequence. Specifically, S24 includes the following steps: S241 , growing a first sublayer.

[0080] The first sublayer was grown by PECVD, the temperature of the reaction chamber was controlled to be 300°C, the pressure was 2 torr, radio frequency excitation was used, SiH4 was introduced as the Si source, and NH3 was introduced as the N source.

[0081] S242 , growing a second sublayer.

[0082] The second sublayer is grown by MOCVD, the temperature of the reaction chamber is controlled at 850°C, the pressure is 150 torr, the growth atmosphere is H2, N source, Ga source and Al source are introduced to grow the AlGaN layer, N source, Ga source and In source are introduced to grow the first InGaN layer, N source, Ga source and N-type doping source are introduced to grow the first GaN layer, and the AlGaN layer, the first InGaN layer and the first GaN layer are repeatedly stacked to grow periodically.

[0083] S243. Grow the third sublayer.

[0084] The third sublayer is grown by MOCVD, the temperature of the reaction chamber is controlled at 850°C, the pressure is 150 torr, the growth atmosphere is N2, N source, Ga source and N-type doping source are introduced to grow the second GaN layer, N source, Ga source and In source are introduced to grow the second InGaN layer, and the second GaN layer and the second InGaN layer are repeatedly stacked and grown periodically.

[0085] S244, growing the fourth sublayer.

[0086] The fourth sublayer is grown by MOCVD, the temperature of the reaction chamber is controlled at 850°C, the pressure is 150 torr, the growth atmosphere is H2, N source, Ga source, In source and Al source are introduced to grow an AlInGaN layer, N source, Ga source and In source are introduced to grow a third InGaN layer, N source, Ga source and N-type doping source are introduced to grow a third GaN layer, and the AlInGaN layer, the third InGaN layer and the third GaN layer are repeatedly stacked to grow periodically.

[0087] S25. Growing a multi-quantum well layer.

[0088] MOCVD is used to grow multiple quantum well layers. The temperature of the reaction chamber is controlled at 795°C and the pressure is 200 torr. N source, Ga source and In source are introduced to grow InGaN quantum well layers. The temperature of the reaction chamber is controlled at 855°C and the pressure is 200 torr. N source, Ga source and Al source are introduced to grow AlGaN quantum barrier layers. InGaN quantum well layers and AlGaN quantum barrier layers are repeatedly stacked to grow periodically.

[0089] S26. Grow an electron blocking layer.

[0090] The electron blocking layer was grown by MOCVD, the temperature of the reaction chamber was controlled at 965° C., the pressure was controlled at 200 torr, and N source, Ga source, Al source and In source were introduced.

[0091] S27. Grow a P-type GaN layer.

[0092] The P-type GaN layer was grown by MOCVD, the temperature of the reaction chamber was controlled at 985°C, the pressure was controlled at 200 torr, and N source, Ga source and P-type doping source were introduced.

[0093] During the MOCVD growth process, the N source is NH3, the Ga source is TMGa, the Al source is TMAl, the In source is TMIn, the N-type doping source is SiH4, and the P-type doping source is CP2Mg.

[0094] Example 2 This embodiment provides a light-emitting diode epitaxial wafer, which differs from the embodiment 1 in that, as the number of alternating stacking cycles increases, the Al component ratio of the AlGaN layer increases from 0.05 to 0.15, and the Si doping concentration of the first GaN layer increases from 1×10 18 cm -3 Increase to 1×10 19 cm -3 .

[0095] The rest are the same as in Example 1.

[0096] Example 3 This embodiment provides a light-emitting diode epitaxial wafer, which differs from embodiment 2 in that after the first InGaN layer is grown, a mixed gas is introduced for treatment. The mixed gas includes N2, H2 and NH3 in a volume ratio of 1:1:1 and the introduction time is 10s.

[0097] The rest are the same as in Example 2.

[0098] Example 4 This embodiment provides a light-emitting diode epitaxial wafer, which differs from the third embodiment in that, as the number of alternating stacking cycles increases, the Al component of the AlInGaN layer decreases from 0.15 to 0.05, the In component ratio of the third InGaN layer increases from 0.02 to 0.08, and the Si doping concentration of the third GaN layer increases from 1×10 19 cm -3 Decrease to 1×10 18 cm -3 .

[0099] The rest are the same as in Example 3.

[0100] Example 5 This embodiment provides a light-emitting diode epitaxial wafer, which differs from embodiment 4 in that after the third InGaN layer is grown, a mixed gas is introduced for treatment. The mixed gas includes N2, H2 and NH3 in a volume ratio of 1:1:1 and the introduction time is 10s.

[0101] The rest are the same as in Example 4.

[0102] Comparative Example 1 This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that no electron-draining layer is provided. Accordingly, the preparation method does not include the preparation of the electron-draining layer.

[0103] The rest are the same as in Example 1.

[0104] The light-emitting diode epitaxial wafers obtained in Examples 1 to 5 and Comparative Example 1 were fabricated into 10 mil × 24 mil LED chips using the same chip process conditions. 300 LED chips were extracted from each sample and tested at 120 mA / 60 mA currents. The improvement in photoelectric efficiency of Examples 1 to 5 relative to Comparative Example 1 was calculated. The specific results are as follows:

[0105] The above is a preferred embodiment of the invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A light-emitting diode epitaxial wafer, characterized in that: It includes a substrate, and a buffer layer, an undoped GaN layer, an N-type GaN layer, an electron dredging layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer sequentially stacked on the substrate; The electron pass layer includes a first sublayer, a second sublayer, a third sublayer and a fourth sublayer stacked in sequence, the first sublayer is a Si3N4 layer, the second sublayer includes a periodically alternately stacked AlGaN layer, a first InGaN layer and a first GaN layer, the third sublayer includes a periodically alternately stacked second GaN layer and a second InGaN layer, and the fourth sublayer includes a periodically alternately stacked AlInGaN layer, a third InGaN layer and a third GaN layer.

2. The light emitting diode epitaxial wafer according to claim 1, wherein: The thickness of the Si3N4 layer is 1nm~10nm.

3. The light emitting diode epitaxial wafer according to claim 1, wherein: The number of cycles of the alternating stacking of the second sublayer is 3 to 8; the AlGaN layer is a Ga-polar AlGaN layer, the Al component ratio is 0.01 to 0.2, and the thickness is 1 nm to 10 nm; the In component ratio of the first InGaN layer is 0.01 to 0.1, and the thickness is 1 nm to 10 nm; the first GaN layer is a Si-doped GaN layer, and the Si doping concentration is 1×10 18 cm -3 ~1×10 19 cm -3 , thickness is 5nm~20nm.

4. The light emitting diode epitaxial wafer according to claim 3, wherein: As the number of alternating stacking cycles increases, the Al component ratio of the AlGaN layer increases, and the Si doping concentration of the first GaN layer increases.

5. The light emitting diode epitaxial wafer according to claim 1, wherein: The number of cycles of the third sub-layer alternating stacking is 5 to 20; the second GaN layer is an N-polarity Si-doped GaN layer, and the Si doping concentration is 1×10 19 cm -3 ~1×10 21 cm -3 , with a thickness of 5nm~10nm; the In component ratio of the second InGaN layer is 0.01~0.1, and the thickness is 1nm~10nm.

6. The light emitting diode epitaxial wafer according to claim 1, wherein: The fourth sublayer has a period of 5 to 20 alternating layers. The AlInGaN layer is a Ga-polar AlInGaN layer with an Al component ratio of 0.01 to 0.2, an In component ratio of 0.01 to 0.1, and a thickness of 1 nm to 10 nm. The third InGaN layer has an In component ratio of 0.01 to 0.1 and a thickness of 1 nm to 10 nm. The third GaN layer is a Si-doped GaN layer with a Si doping concentration of 1×10 18 cm -3 ~1×10 19 cm -3 , thickness is 5nm~20nm.

7. The light emitting diode epitaxial wafer according to claim 6, wherein: As the number of alternating stacking cycles increases, the Al component ratio of the AlInGaN layer decreases, the In component ratio of the AlInGaN layer increases, and the Si doping concentration of the third GaN layer decreases.

8. A method for preparing a 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 undoped GaN layer, an N-type GaN layer, an electron dredging layer, a multi-quantum well layer, an electron blocking layer, and a P-type GaN layer on the substrate; The electron pass layer includes a first sublayer, a second sublayer, a third sublayer and a fourth sublayer stacked in sequence, the first sublayer is a Si3N4 layer, the second sublayer includes a periodically alternately stacked AlGaN layer, a first InGaN layer and a first GaN layer, the third sublayer includes a periodically alternately stacked second GaN layer and a second InGaN layer, and the fourth sublayer includes a periodically alternately stacked AlInGaN layer, a third InGaN layer and a third GaN layer.

9. The method for preparing a light emitting diode epitaxial wafer according to claim 8, wherein: The growth temperature of the second sub-layer is 800° C. to 900° C., the growth pressure is 50 torr to 500 torr, and the growth atmosphere is H2; The growth temperature of the third sub-layer is 800° C. to 900° C., the growth pressure is 50 torr to 500 torr, and the growth atmosphere is N2; The growth temperature of the fourth sub-layer is 800° C. to 900° C., the growth pressure is 50 torr to 500 torr, and the growth atmosphere is H 2 .

10. The method for preparing a light emitting diode epitaxial wafer according to claim 8, wherein: After the growth of the first InGaN layer and the third InGaN layer is completed, a mixed gas is introduced for treatment, wherein the mixed gas includes N2, H2 and NH3 in a volume ratio of 1:1:1 to 1:20:10, and the introduction time is 5s to 15s.

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