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

Abstract

The application discloses a light-emitting diode epitaxial wafer and a preparation method thereof. The light-emitting diode epitaxial wafer comprises a substrate, a buffer layer, a U-GaN layer, an N-GaN layer, a light-emitting layer, an electron blocking layer and a P-GaN layer which are sequentially stacked on the substrate; the light-emitting layer comprises a first step layer and a second step layer which are sequentially stacked on the N-GaN layer; the first step layer is a periodic structure formed by alternately stacking an AlInGaN layer and a Si3N4 layer; and the second step layer is a periodic structure formed by alternately stacking an AlGaN barrier layer, an InGaN well layer and a GaN protective layer. The light-emitting diode prepared by the application has improved light-emitting efficiency and light-emitting wavelength uniformity.

Description

Technical Field

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

[0002] Light-emitting diodes (LEDs) have been widely used in various fields due to their advantages such as long lifespan and low power consumption. Especially with the significant improvement in their lighting performance, LEDs are commonly used as light-emitting devices in the lighting industry. Among them, III-V compound semiconductors, represented by GaN, and particularly GaN-based LEDs, have attracted widespread attention due to their wide bandgap, high luminous efficiency, high electron saturation drift velocity, and stable chemical properties, showing great application potential in optoelectronic devices such as high-brightness blue LEDs and blue lasers.

[0003] The quality of the epitaxial structure is a decisive factor affecting chip quality, especially by changing the crystal quality of the light-emitting layer and the incorporation rate of In, which can directly affect chip performance. Traditional methods to improve the performance of the light-emitting layer mostly involve optimizing the epitaxial materials and structure, such as optimizing the underlying structure. These methods involve many parameters, are complex to adjust, are time-consuming, and can easily affect other performance aspects of the LED chip. Furthermore, the uneven distribution of In leads to poor wavelength uniformity within the chip. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a light-emitting diode epitaxial wafer that can improve the crystal quality of the light-emitting layer, thereby improving the luminous efficiency.

[0005] The technical problem to be solved by the present invention is to provide a method for preparing an epitaxial wafer of a light-emitting diode, which produces an epitaxial wafer with high luminous efficiency.

[0006] To achieve the above-mentioned technical effects, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate, and a buffer layer, a U-GaN layer, an N-GaN layer, a light-emitting layer, an electron blocking layer and a P-GaN layer sequentially stacked on the substrate;

[0007] The light-emitting layer includes a first step layer and a second step layer sequentially stacked on the N-GaN layer;

[0008] The first step layer is a periodic structure formed by alternating AlInGaN layers and Si3N4 layers; the second step layer is a periodic structure formed by alternating AlGaN barrier layers, InGaN well layers and GaN protective layers.

[0009] As an improvement to the above technical solution, the number of cycles of the first step layer is 5 to 10; the number of cycles of the second step layer is 5 to 15.

[0010] As an improvement to the above technical solution, the Al composition ratio of the AlInGaN layer is 0.01 to 0.3, the In composition ratio is 0.01 to 0.1, and the thickness is 2 nm to 10 nm; along the epitaxial growth direction, the Al composition ratio of the AlInGaN layer in each cycle increases.

[0011] The thickness of the Si3N4 layer is 2nm to 10nm.

[0012] As an improvement to the above technical solution, the Al composition ratio of the AlGaN barrier layer is 0.01 to 0.3, and the thickness is 2 nm to 10 nm; along the epitaxial growth direction, the Al composition ratio of the AlGaN barrier layer in each cycle increases.

[0013] The InGaN well layer has an In composition ratio of 0.1 to 0.3 and a thickness of 1 nm to 10 nm.

[0014] The thickness of the GaN protective layer is 5nm to 15nm.

[0015] As an improvement to the above technical solution, the AlGaN barrier layer is a Si-doped AlGaN barrier layer with a Si doping concentration of 1×10⁻⁶. 13 cm -3 ~1×10 16 cm -3 ;

[0016] Along the epitaxial growth direction, the Si doping concentration of the AlGaN barrier layer decreases in each cycle.

[0017] Accordingly, the present invention also discloses a method for preparing a light-emitting diode epitaxial wafer, which includes the following steps:

[0018] A substrate is provided on which a buffer layer, a U-GaN layer, an N-GaN layer, a light-emitting layer, an electron-blocking layer and a P-GaN layer are sequentially grown.

[0019] The light-emitting layer includes a first step layer and a second step layer sequentially stacked on the N-GaN layer;

[0020] The first step layer is a periodic structure formed by alternating AlInGaN layers and Si3N4 layers; the second step layer is a periodic structure formed by alternating AlGaN barrier layers, InGaN well layers and GaN protective layers.

[0021] As an improvement to the above technical solution, the growth temperature of the AlInGaN layer is 800℃~1000℃, and the growth pressure is 100Torr~500Torr;

[0022] The growth temperature of the Si3N4 layer is 800℃~1000℃, and the growth pressure is 100Torr~500Torr.

[0023] As an improvement to the above technical solution, the growth temperature of the AlGaN barrier layer is 800℃~900℃, and the growth pressure is 150Torr~500Torr;

[0024] The growth temperature of the InGaN well layer is 750–850℃, and the growth pressure is 150 Torr–500 Torr.

[0025] The growth temperature of the GaN protective layer is 800℃~900℃, and the growth pressure is 150Torr~500Torr.

[0026] As an improvement to the above technical solution, after the InGaN well layer is grown in each cycle, the MO source is interrupted and N2 is introduced for processing, with a processing time of 20s to 30s.

[0027] Accordingly, the present invention also discloses a light-emitting diode, including the above-mentioned light-emitting diode epitaxial wafer.

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

[0029] The luminescent layer of this invention comprises a first-step layer and a second-step layer stacked sequentially. The first-step layer is a periodic structure formed by alternating layers of AlInGaN and Si3N4 layers, and the second-step layer is a periodic structure formed by alternating layers of AlGaN barrier layer, InGaN well layer, and GaN protective layer. The formation of the superlattice microstrips in the first-step layer can buffer the compressive stress from the underlying layer, reduce the electron migration velocity, and block dislocation propagation. During the growth of the second-step layer, the growth temperature and growth atmosphere of the barrier and well layers are controlled to improve the interface clarity between the barrier and well layers, increase the effective emission peak, and simultaneously improve the uniform distribution of In, thus improving wavelength uniformity. After the well layer is grown, a protective layer is grown to protect the well layer and further reduce In precipitation. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the light-emitting diode epitaxial wafer in Embodiment 1 of the present invention;

[0031] Figure 2 This is a flowchart of the method for preparing the epitaxial wafer of a light-emitting diode in Embodiment 1 of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0033] like Figure 1 As shown, an embodiment of the present invention provides a light-emitting diode epitaxial wafer, including a substrate 1, and a buffer layer 2, a U-GaN layer 3, an N-GaN layer 4, a light-emitting layer 5, an electron blocking layer 6 and a P-GaN layer 7 sequentially stacked on the substrate 1.

[0034] The light-emitting layer 5 comprises a first stepped layer and a second stepped layer sequentially stacked on the N-GaN layer 4. The first stepped layer is a periodic structure formed by alternating layers of AlInGaN and Si3N4 layers. The formation of superlattice microstrips after the AlInGaN and Si3N4 layers form a superlattice structure can buffer the compressive stress from the underlying layer. Since the AlInGaN and Si3N4 layers have different band gaps, electron migration speed is reduced and dislocation propagation is blocked at the interface between the AlInGaN and Si3N4 layers. The second stepped layer is a periodic structure formed by alternating layers of AlGaN barrier layer, InGaN well layer, and GaN protective layer. Controlling the growth temperature and atmosphere of the AlGaN barrier layer and InGaN well layer improves the interface clarity between them, increases the effective emission peak, and improves the uniform distribution of In, thus enhancing wavelength uniformity. Furthermore, a GaN protective layer is grown after the InGaN well layer to protect it and further reduce In precipitation.

[0035] In one embodiment, the number of cycles in the first step layer is 5 to 10. The number of cycles in the second step layer is 5 to 15.

[0036] In one embodiment, the Al composition ratio of the AlInGaN layer is 0.01 to 0.3. For example, the Al composition ratio of the AlInGaN layer is 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3, but is not limited thereto. The In composition ratio of the AlInGaN layer is 0.01 to 0.1. For example, the In composition ratio of the AlInGaN layer is 0.01, 0.02, 0.05, 0.08, or 0.1, but is not limited thereto. The thickness of the AlInGaN layer is 2 nm to 10 nm. For example, the thickness of the AlInGaN layer is 2 nm, 4 nm, 5 nm, 6 nm, 8 nm, or 10 nm, but is not limited thereto. Preferably, along the epitaxial growth direction, the Al composition ratio of the AlInGaN layer increases in each cycle, which can continuously block electron overflow. The thickness of the Si3N4 layer is 2nm to 10nm. For example, the thickness of the Si3N4 layer is 2nm, 4nm, 5nm, 6nm, 8nm or 10nm, but is not limited thereto.

[0037] In one embodiment, the Al composition ratio of the AlGaN barrier layer is 0.01 to 0.3. For example, the Al composition ratio of the AlGaN barrier layer is 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3, but is not limited thereto. The thickness of the AlGaN barrier layer is 2 nm to 10 nm. For example, the thickness of the AlGaN barrier layer is 2 nm, 4 nm, 5 nm, 6 nm, 8 nm, or 10 nm, but is not limited thereto. Preferably, the Al composition ratio of the AlGaN barrier layer increases in each cycle along the epitaxial growth direction. The In composition ratio of the InGaN well layer is 0.1 to 0.3. For example, the In composition ratio of the InGaN well layer is 0.1, 0.15, 0.2, 0.25, or 0.3, but is not limited thereto. The thickness of the InGaN well layer is 1 nm to 10 nm. For example, the thickness of the InGaN well layer is 2 nm, 4 nm, 5 nm, 6 nm, 8 nm, or 10 nm, but is not limited thereto. The thickness of the GaN protective layer is 5 nm to 15 nm. For example, the thickness of the GaN protective layer is 5 nm, 6 nm, 8 nm, 10 nm, 12 nm, or 15 nm, but is not limited thereto.

[0038] In one embodiment, the AlGaN barrier layer is a Si-doped AlGaN barrier layer with a Si doping concentration of 1×10⁻⁶. 13 cm -3 ~1×10 16 cm -3 For example, the Si doping concentration is 1×10⁻⁶. 13 cm -3 5×10 13cm -3 1×10 14 cm -3 5×10 14 cm -3 1×10 15 cm -3 5×10 15 cm -3 Or 1×10 16 cm -3 However, this is not the only possibility. Preferably, the Si doping concentration of the AlGaN barrier layer decreases in each cycle along the epitaxial growth direction, which can reduce the resistivity of the AlGaN barrier layer.

[0039] In addition to the light-emitting layer mentioned above, the other features of the layered structure of the present invention are as follows:

[0040] The substrate 1 can be selected from one of the following: (0001) sapphire substrate, AlN substrate, Si(111) substrate, and SiC(0001) substrate. Preferably, the substrate 1 is a sapphire substrate.

[0041] The buffer layer 2 is an AlGaN buffer layer or an AlN buffer layer, with a thickness of 20 nm to 100 nm. Preferably, the buffer layer 2 is an AlN buffer layer. The AlN buffer layer provides nucleation centers aligned with the substrate, releasing stress caused by lattice mismatch between the epitaxial structure and the substrate, as well as thermal stress caused by thermal expansion coefficient mismatch. This provides a flat nucleation surface for the growth of the epitaxial structure, reducing its contact angle and enabling island-grown GaN grains to connect into a surface within a smaller thickness, transforming into two-dimensional epitaxial growth. This improves the crystal quality of the subsequently deposited GaN layer, reduces dislocation density, and increases the radiative recombination efficiency of the multi-quantum-well layer.

[0042] The thickness of the U-GaN layer 3 is 1μm to 3μm.

[0043] The N-GaN layer 4 can be Si-doped, with a Si doping concentration of 1×10⁴. 19 cm -3 ~5×10 20 cm -3 The thickness of the N-GaN layer 4 is 1μm to 5μm. The N-GaN layer provides sufficient electrons for LED light emission; secondly, the resistivity of the N-GaN layer is higher than that of the transparent electrode on the P-GaN layer, so sufficient Si doping can effectively reduce the resistivity of the N-GaN layer; finally, sufficient thickness of the N-GaN layer can effectively release stress and improve the luminous efficiency of the light-emitting diode.

[0044] The electron blocking layer 6 can be an AlGaN electron blocking layer with an Al composition of 0.4–0.8% and a thickness of 10 nm–100 nm. The AlGaN electron blocking layer can effectively limit electron overflow and reduce the blocking of holes, thereby improving the injection efficiency of holes into the electron well, reducing carrier Auger recombination, and improving the luminous efficiency of the light-emitting diode.

[0045] The P-GaN layer 7 can be Mg-doped, with a Mg doping concentration of 1×10⁻⁶. 19 cm -3 ~5×10 20 cm -3 Excessive Mg doping concentration can damage crystal quality, while low Mg doping concentration can affect hole concentration. The thickness of the P-GaN layer 7 is 20 nm to 200 nm.

[0046] like Figure 2 As shown, this invention also discloses a method for fabricating a light-emitting diode epitaxial wafer, comprising the following steps:

[0047] S100 provides a substrate

[0048] A sapphire substrate was selected, and the reaction chamber temperature was controlled at 1000℃~1200℃ and the pressure at 200Torr~600Torr. The sapphire substrate was subjected to high-temperature annealing for 5min~8min in H2 atmosphere to clean the particles and oxides on the surface of the sapphire substrate.

[0049] S200 growth buffer layer

[0050] The reaction chamber temperature is controlled at 500℃~700℃, the pressure at 200Torr~400Torr, NH3 is introduced as the N source, N2 and H2 are introduced as the carrier gas, TMGa is introduced as the Ga source, and TMAl is introduced as the Al source.

[0051] S300 grows U-GaN layer

[0052] The reaction chamber temperature was controlled at 1100℃~1150℃, the pressure at 100Torr~500Torr, NH3 was introduced as the N source, N2 and H2 were introduced as the carrier gas, and TMGa was introduced as the Ga source.

[0053] S400 growth of N-GaN layer

[0054] The reaction chamber temperature was controlled at 1000℃~1300℃, the pressure at 50Torr~300Torr, NH3 was introduced as the N source, N2 and H2 were introduced as the carrier gas, TMGa was introduced as the Ga source, and SiH4 was introduced as the doping source.

[0055] The S500 light-emitting layer is grown, specifically, in one embodiment, including the following steps:

[0056] S501 growth first step

[0057] The reaction chamber temperature was controlled at 800℃~1000℃ and the pressure at 100Torr~500Torr. NH3 was introduced as the N source, N2 and H2 as the carrier gas, TEGa was introduced as the Ga source, TMIn as the In source, and TMAl as the Al source to grow an AlInGaN layer. The reaction chamber temperature was controlled at 800℃~1000℃ and the pressure at 100Torr~500Torr. NH3 was introduced as the N source, N2 and H2 as the carrier gas, and SiH4 as the Si source to grow a Si3N4 layer. The AlInGaN and Si3N4 layers were then repeatedly stacked and periodically grown.

[0058] S502 grows the second tier.

[0059] The reaction chamber temperature was controlled at 800℃~900℃ and the pressure at 150Torr~500Torr. NH3 was introduced as the N source, N2 and H2 as the carrier gas, TEGa as the Ga source, TMAl as the Al source, and SiH4 as the doping source to grow an AlGaN barrier layer. The reaction chamber temperature was controlled at 750℃~850℃ and the pressure at 100Torr~500Torr. NH3 was introduced as the N source, N2 as the carrier gas, TEGa as the Ga source, and TMIn as the In source to grow an InGaN well layer. The reaction chamber temperature was controlled at 800℃~900℃ and the pressure at 150Torr~500Torr. NH3 was introduced as the N source, H2 as the carrier gas, and TEGa as the Ga source to grow a GaN protective layer. The AlGaN barrier layer, InGaN well layer, and GaN protective layer were repeatedly stacked and periodically grown. When growing the AlGaN barrier layer, increasing the temperature to a range of 50°C to 100°C different from the InGaN well layer, and introducing H2 and N2 as carrier gases, can continuously improve the interface clarity between the AlGaN barrier layer and the InGaN well layer, increase the generation of effective emission peaks, and improve the uniform distribution of the In component, thereby improving wavelength uniformity.

[0060] In one embodiment, after the InGaN well layer growth is completed in each cycle, the MO source is interrupted and N2 is introduced for treatment. The treatment time is 20s to 30s, which can reduce the precipitation of In components and the precipitation of C impurities, improve the crystal quality of the well layer, and improve the recombination efficiency of electrons and holes.

[0061] S600 growth electron barrier layer

[0062] The reaction chamber temperature is controlled at 1000℃~1100℃, the pressure at 100Torr~500Torr, NH3 is introduced as the N source, N2 and H2 are introduced as the carrier gas, TMGa is introduced as the Ga source, and TMAl is introduced as the Al source.

[0063] S700 growth of P-GaN layer

[0064] The reaction chamber temperature was controlled at 1000℃~1100℃, the pressure at 100Torr~600Torr, NH3 was introduced as the N source, TMGa was introduced as the Ga source, and CP2Mg was introduced as the doping source.

[0065] The present invention will be further illustrated below with specific embodiments.

[0066] Example 1

[0067] This embodiment provides a light-emitting diode epitaxial wafer, including a substrate and a buffer layer, a U-GaN layer, an N-GaN layer, a light-emitting layer, an electron blocking layer and a P-GaN layer sequentially stacked on the substrate.

[0068] The substrate is a sapphire substrate.

[0069] The buffer layer is an AlN buffer layer with a thickness of 50nm.

[0070] The thickness of the U-GaN layer is 2 μm.

[0071] The Si doping concentration in the N-GaN layer is 2.5 × 10⁻⁶. 19 cm -3 The thickness is 2μm.

[0072] The light-emitting layer comprises a first-step layer and a second-step layer stacked sequentially. The first-step layer is a periodic structure consisting of alternating AlInGaN and Si3N4 layers, with a period number of 5. The AlInGaN layer has an Al content of 0.05% and an In content of 0.02%, with a thickness of 5 nm; the Si3N4 layer also has a thickness of 5 nm.

[0073] The second-step layer is a periodic structure formed by alternating layers of AlGaN barrier layer, InGaN well layer and GaN protective layer, with a period number of 5. The Al content of the AlGaN barrier layer is 0.01 and the thickness is 5 nm; the In content of the InGaN well layer is 0.1 and the thickness is 5 nm; the thickness of the GaN protective layer is 5 nm.

[0074] The electron blocking layer is an AlGaN electron blocking layer with an Al content of 0.75% and a thickness of 30 nm.

[0075] The Mg doping concentration in the P-GaN layer is 5 × 10⁻⁶.19 cm -3 The thickness is 100nm.

[0076] The above-mentioned method for fabricating an epitaxial wafer of a light-emitting diode includes the following steps:

[0077] S100 provides a substrate

[0078] A sapphire substrate was selected, and the reaction chamber temperature was controlled at 1000℃ and the pressure at 400 Torr. The sapphire substrate was subjected to high-temperature annealing for 6 minutes in an H2 atmosphere.

[0079] S200 nucleation layer

[0080] The reaction chamber temperature was controlled at 600℃ and the pressure at 250 Torr. NH3 was introduced as the N source, N2 and H2 were introduced as the carrier gas, and TMAl was introduced as the Al source.

[0081] S300 grows U-GaN layer

[0082] The reaction chamber temperature was controlled at 1100℃ and the pressure at 300 Torr. NH3 was introduced as the N source, N2 and H2 were introduced as the carrier gas, and TMGa was introduced as the Ga source.

[0083] S400 growth of N-GaN layer

[0084] The reaction chamber temperature was controlled at 1200℃ and the pressure at 100 Torr. NH3 was introduced as the N source, N2 and H2 were introduced as the carrier gas, TMGa was introduced as the Ga source, and SiH4 was introduced as the doping source.

[0085] The S500 light-emitting layer is grown, specifically including the following steps:

[0086] S501 growth first step

[0087] The reaction chamber temperature was controlled at 900℃ and the pressure at 200 Torr. NH3 was introduced as the N source, N2 and H2 as the carrier gas, TEGa was introduced as the Ga source, TMIn as the In source, and TMAl as the Al source to grow an AlInGaN layer. The reaction chamber temperature was controlled at 850℃ and the pressure at 120 Torr. NH3 was introduced as the N source, N2 and H2 as the carrier gas, and SiH4 as the Si source to grow a Si3N4 layer. The AlInGaN and Si3N4 layers were then repeatedly stacked and periodically grown.

[0088] S502 grows the second tier.

[0089] The reaction chamber temperature was controlled at 850℃ and the pressure at 200 Torr. NH3 was introduced as the N source, N2 and H2 as the carrier gas, TEGa as the Ga source, TMAl as the Al source, and SiH4 as the doping source to grow an AlGaN barrier layer. The reaction chamber temperature was controlled at 780℃ and the pressure at 200 Torr. NH3 was introduced as the N source, N2 as the carrier gas, TEGa as the Ga source, and TMIn as the In source to grow an InGaN well layer. The reaction chamber temperature was controlled at 830℃ and the pressure at 200 Torr. NH3 was introduced as the N source, H2 as the carrier gas, and TEGa as the Ga source to grow a GaN protective layer. The AlGaN barrier layer, InGaN well layer, and GaN protective layer were repeatedly stacked and periodically grown.

[0090] S600 growth electron barrier layer

[0091] The reaction chamber temperature was controlled at 1050℃ and the pressure at 200 Torr. NH3 was introduced as the N source, N2 and H2 were introduced as the carrier gas, TMGa was introduced as the Ga source, and TMAl was introduced as the Al source.

[0092] S800 growth of P-GaN layer

[0093] The reaction chamber temperature was controlled at 1050℃ and the pressure at 200 Torr. NH3 was introduced as the N source, TMGa was introduced as the Ga source, and CP2Mg was introduced as the doping source.

[0094] Example 2

[0095] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 1 in that the AlGaN barrier layer is a Si-doped AlGaN barrier layer with a Si doping concentration of 5 × 10⁻⁶. 15 cm -3 Everything else is the same as in Example 1.

[0096] Example 3

[0097] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 1 in that the AlGaN barrier layer is a Si-doped AlGaN barrier layer, and the Si doping concentration of the AlGaN barrier layer decreases in each cycle along the epitaxial growth direction, from 1×10⁻⁶. 16 cm -3 Reduced to 1×10 13 cm -3 Everything else is the same as in Example 1.

[0098] Example 4

[0099] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 3 in that, along the epitaxial growth direction, the Al composition ratio of the AlGaN barrier layer in each cycle increases from 0.02 to 0.06. All other aspects are the same as in Embodiment 3.

[0100] Example 5

[0101] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 4 in that the Al composition ratio of the AlInGaN barrier layer in each cycle increases from 0.02 to 0.06 along the epitaxial growth direction. All other aspects are the same as in Embodiment 4.

[0102] Example 6

[0103] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 5 in that, after the InGaN well layer growth is completed in each cycle, the MO source is interrupted, and N2 is introduced for processing, with a processing time of 25 seconds. All other aspects are the same as in Embodiment 5.

[0104] Comparative Example 1

[0105] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that the light-emitting layer is a periodic structure formed by alternating AlGaN barrier layers and InGaN well layers. Correspondingly, the fabrication method does not include the preparation of the first step layer and the GaN protective layer. Everything else is the same as in Example 1.

[0106] Comparative Example 2

[0107] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that the light-emitting layer is a periodic structure formed by alternating layers of AlGaN barrier layer, InGaN well layer, and GaN protective layer. Correspondingly, the fabrication method does not include the preparation of the first step layer. All other aspects are the same as in Example 1.

[0108] Performance testing:

[0109] The light-emitting diode epitaxial wafers prepared in Examples 1 to 6, Comparative Example 1 and Comparative Example 2 were used to fabricate LED chips of 10mil × 24mil, and their photoelectric performance was tested.

[0110] (1) Luminous brightness: Tested at 120mA / 60mA current, and the photoelectric efficiency improvement of Examples 1 to 6 and Comparative Example 2 compared to Comparative Example 1 was calculated.

[0111] (2) Wavelength uniformity: PL spectroscopy was used to measure the peak wavelength at different positions of the chips prepared in Examples 1 to 6, Comparative Example 1 and Comparative Example 2, and the standard deviation of the peak wavelength of each chip was calculated.

[0112] The test results are shown in Table 1.

[0113] Table 1. Photoelectric performance test results of LED epitaxial wafers

[0114]

[0115] As shown in Table 1, the light-emitting layer structure of the present invention can significantly improve the brightness and wavelength uniformity of the light-emitting diode.

[0116] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and 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, a U-GaN layer, an N-GaN layer, a light-emitting layer, an electron-blocking layer and a P-GaN layer sequentially stacked on the substrate; The light-emitting layer includes a first step layer and a second step layer sequentially stacked on the N-GaN layer; The first step layer is a periodic structure formed by alternating layers of AlInGaN and Si3N4; the second step layer is a periodic structure formed by alternating layers of AlGaN barrier, InGaN well and GaN protective layer. The first step layer has 5 to 10 cycles; the second step layer has 5 to 15 cycles. The Al component of the AlInGaN layer is 0.01~0.3, the In component is 0.01~0.1, and the thickness is 2nm~10nm; along the epitaxial growth direction, the Al component of the AlInGaN layer increases in each cycle. The thickness of the Si3N4 layer is 2nm~10nm; The Al composition of the AlGaN barrier layer is 0.01~0.3, and the thickness is 2nm~10nm; along the epitaxial growth direction, the Al composition of the AlGaN barrier layer increases in each cycle. The InGaN well layer has an In composition ratio of 0.1~0.3 and a thickness of 1nm~10nm; The thickness of the GaN protective layer is 5nm~15nm.

2. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The AlGaN barrier layer is a Si-doped AlGaN barrier layer with a Si doping concentration of 1×10⁻⁶. 13 cm -3 ~1×10 16 cm -3 ; Along the epitaxial growth direction, the Si doping concentration of the AlGaN barrier layer decreases in each cycle.

3. A method for fabricating a light-emitting diode epitaxial wafer, used to fabricate the light-emitting diode epitaxial wafer as described in claim 1 or 2, characterized in that, Includes the following steps: A substrate is provided on which a buffer layer, a U-GaN layer, an N-GaN layer, a light-emitting layer, an electron-blocking layer and a P-GaN layer are sequentially grown. The light-emitting layer includes a first step layer and a second step layer sequentially stacked on the N-GaN layer; The first step layer is a periodic structure formed by alternating AlInGaN layers and Si3N4 layers; the second step layer is a periodic structure formed by alternating AlGaN barrier layers, InGaN well layers and GaN protective layers.

4. The method for fabricating a light-emitting diode epitaxial wafer as described in claim 3, characterized in that, The growth temperature of the AlInGaN layer is 800℃~1000℃, and the growth pressure is 100Torr~500Torr; The growth temperature of the Si3N4 layer is 800℃~1000℃, and the growth pressure is 100Torr~500Torr.

5. The method for fabricating a light-emitting diode epitaxial wafer as described in claim 3, characterized in that, The growth temperature of the AlGaN barrier layer is 800℃~900℃, and the growth pressure is 150Torr~500Torr; The growth temperature of the InGaN well layer is 750~850℃, and the growth pressure is 150Torr~500Torr. The growth temperature of the GaN protective layer is 800℃~900℃, and the growth pressure is 150Torr~500Torr.

6. The method for fabricating a light-emitting diode epitaxial wafer as described in claim 3, characterized in that, After the InGaN well layer is grown in each cycle, the MO source is interrupted and N2 is introduced for processing, which takes 20 to 30 seconds.

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

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