LED epitaxial structure, manufacturing method thereof and LED device

Abstract

The present application relates to a LED epitaxial structure, a manufacturing method thereof and a LED device. The LED epitaxial structure comprises an N-type confinement layer, an active layer stacked on the N-type confinement layer, and a P-type confinement layer comprising a non-doped layer and a P-type doped layer stacked on the active layer in sequence, wherein the P-type doped layer comprises a first doped layer and a second doped layer stacked on the non-doped layer in turn, and the P-type doping concentration of the first doped layer is greater than that of the second doped layer. The present application improves the light emitting efficiency of the LED.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to an LED epitaxial structure, its manufacturing method, and an LED device. Background Technology

[0002] A light-emitting diode (LED) is an electronic device that directly converts electrical energy into light energy by generating photons through the radiative recombination of conduction band electrons and valence band holes in a semiconductor material.

[0003] Therefore, improving the luminous efficiency of LEDs is an urgent problem to be solved. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide an LED epitaxial structure and its manufacturing method, as well as an LED device, in order to solve the problem of improving the luminous efficiency of LEDs.

[0005] An LED epitaxial structure, comprising:

[0006] N-type confinement layer;

[0007] An active layer is stacked on the N-type confinement layer; and

[0008] The P-type confinement layer includes an undoped layer and a P-type doped layer sequentially stacked on the active layer. The P-type doped layer includes a first doped layer and a second doped layer alternately stacked on the undoped layer. The P-type doping concentration of the first doped layer is greater than that of the second doped layer.

[0009] In the aforementioned LED epitaxial structure, an N-type confinement layer, an active layer, and a P-type confinement layer are stacked sequentially. The P-type confinement layer comprises an undoped layer and a P-type doped layer stacked sequentially. The P-type doped layer includes alternating first and second doped layers. The P-type doping concentration of the first doped layer is greater than that of the second doped layer. The higher P-type doping concentration of the first doped layer increases the potential barrier of the P-type confinement layer, effectively preventing fast-moving electrons from entering the P-type confinement layer and recombinating with holes. This reduces the number of electrons overflowing from the active layer, increases the recombination probability of electrons and holes in the active layer, improves the internal quantum efficiency of the LED, and thus improves the luminous efficiency of the LED. Furthermore, the higher P-type doping concentration of the first doped layer also increases the number of holes in the P-type confinement layer, which is beneficial for hole injection into the active layer and recombination with electrons, further increasing the recombination probability of electrons and holes in the active layer, ultimately improving the luminous efficiency of the LED. In addition, the second doped layer with a lower P-type doping concentration is stacked alternately with the first doped layer, and an undoped layer is provided between the P-type doped layer and the active layer. This can effectively prevent the P-type dopant from overflowing into the active layer and affecting the recombination of electrons and holes in the active layer.

[0010] Optionally, the P-type doping concentration of the first doped layer is 1.5 to 2.5 times that of the P-type doping concentration of the second doped layer.

[0011] The P-type doping concentration in the first doped layer is 0.5 to 1.5 times higher than that in the second doped layer, which significantly increases the P-type doping concentration. This increases the potential barrier of the P-type confinement layer, preventing electrons from entering it, and also increases the number of holes in the P-type confinement layer, which is beneficial for hole injection into the active layer. These two factors combined increase the recombination probability of electrons and holes in the active layer, thereby improving the internal quantum efficiency of the LED and ultimately its luminous efficiency. Furthermore, the P-type doping concentration is not increased indefinitely, thus preventing P-type dopant from overflowing into the active layer and causing adverse effects.

[0012] Optionally, the P-type doping concentration of the first doped layer is 5.1E+17 to 9E+17, and the P-type doping concentration of the second doped layer is 2.5E+17 to 4.5E+17.

[0013] The P-type doping concentration of the P-type confinement layer is typically 2.5E+17 to 4.5E+17. The P-type doping concentration of the first doped layer is higher than that of the P-type confinement layer. Increasing the P-type doping concentration increases the potential barrier of the P-type confinement layer, preventing electrons from entering, and also increases the number of holes in the P-type confinement layer, which is beneficial for hole injection into the active layer. These two aspects combined increase the recombination probability of electrons and holes in the active layer, thereby improving the internal quantum efficiency of the LED and ultimately its luminous efficiency. Furthermore, the P-type doping concentration of the second doped layer is consistent with that of the P-type confinement layer, allowing for improvements to the original structure of the P-type confinement layer, resulting in better overall matching.

[0014] Optionally, the thickness of the first doped layer is less than the thickness of the second doped layer.

[0015] The smaller thickness of the first doped layer is beneficial for increasing the P-type doping concentration, thereby ultimately improving the luminous efficiency of the LED. The larger thickness of the second doped layer effectively prevents the excessively high P-type doping concentration in the first doped layer from overflowing into the active layer.

[0016] Optionally, the thickness of the second doped layer is 1.5 to 2.5 times the thickness of the first doped layer.

[0017] With the P-type doping concentration of the first doped layer being 0.5 to 1.5 times higher than that of the second doped layer, and the thickness of the second doped layer being 0.5 to 1.5 times greater than that of the first doped layer, the two can work together.

[0018] Optionally, the thickness of the P-type doped layer is 3 to 5 times the thickness of the undoped layer.

[0019] The thickness of the P-type doped layer is 2 to 4 times greater than that of the undoped layer. The P-type confinement layer can provide a sufficient number of holes for injection into the active layer, while the undoped layer can prevent P-type dopants from overflowing into the active layer.

[0020] Optionally, the P-type doped layer includes multiple periods, each period including the first doped layer and the second doped layer stacked on the first doped layer.

[0021] In the same period, the first doped layer is closer to the undoped layer than the second doped layer. The first doped layer is located between the undoped layer and the second doped layer, which helps to prevent the P-type dopant from overflowing the P-type confinement layer.

[0022] Optionally, the P-type doped layer comprises at least two periods.

[0023] The P-type doped layer includes at least two periods, each period including a first doped layer and a second doped layer stacked on the first doped layer. The first and second doped layers are stacked alternately, which is beneficial for hole injection into the active layer and at the same time prevents the P-type dopant from overflowing from the active layer.

[0024] Based on the same inventive concept, this application also provides an LED device, including an N-type electrode, a P-type electrode and the above-mentioned LED epitaxial structure, wherein the N-type electrode is disposed on the N-type confinement layer and the P-type electrode is disposed on the P-type confinement layer.

[0025] Based on the same inventive concept, this application also provides a method for fabricating an LED epitaxial structure, comprising:

[0026] Provide substrate;

[0027] An N-type confinement layer and an active layer are sequentially grown on the substrate;

[0028] An undoped layer is grown on the active layer;

[0029] A first doped layer and a second doped layer are alternately grown on the undoped layer to form a P-type doped layer. The P-type doped layer and the undoped layer form a P-type confinement layer. The P-type doping concentration of the first doped layer is greater than that of the second doped layer. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the LED epitaxial structure in one embodiment of this application;

[0031] Figure 2 This is a schematic diagram of the structure of the P-type confinement layer in one embodiment of this application;

[0032] Figure 3 This is a schematic diagram of the barrier of a P-type doped layer in one embodiment of this application;

[0033] Figure 4 This is a schematic diagram of the active layer structure in one embodiment of this application;

[0034] Figure 5 This is a flowchart of a method for preparing an LED epitaxial structure according to an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures:

[0036] 10-N type confinement layer;

[0037] 20 - Active layer, 21 - Quantum well layer, 22 - Quantum barrier layer, 23 - First waveguide layer, 24 - Second waveguide layer;

[0038] 30 - P-type confinement layer, 31 - undoped layer, 32 - P-type doped layer, 321 - first doped layer, 322 - second doped layer;

[0039] 40-substrate;

[0040] 50-Buffer layer;

[0041] 60-Reflective layer;

[0042] 70-Current spreading layer;

[0043] 80 - Transition layer. Detailed Implementation

[0044] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0046] AlGaInP-based LEDs consist of sequentially stacked N-type confinement layers, an active layer, and a P-type confinement layer. The N-type confinement layer is an N-type doped AlInP layer used to generate electrons. The P-type confinement layer is a P-type doped AlInP layer used to generate holes. The active layer comprises alternating layers of quantum wells and quantum barriers, each made of AlGaInP with different compositional amounts. Electrons generated in the N-type confinement layer and holes generated in the P-type confinement layer migrate to the active layer and recombine radiatively to emit light in the desired wavelength range.

[0047] However, electrons have a smaller effective mass and a greater mobility than holes. Some electrons migrate to the p-type confinement layer and recombine with holes, reducing the number of charge carriers (including electrons and holes) that emit radiation through recombination in the active layer. This lowers the probability of electron-hole recombination in the active layer. Since electron-hole recombination in the p-type confinement layer cannot produce light of the required wavelength, it affects the internal quantum efficiency of the LED, resulting in lower luminous efficiency.

[0048] Therefore, this application aims to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in subsequent embodiments.

[0049] See Figure 1 This application provides an LED epitaxial structure, which includes an N-type confinement layer 10, an active layer 20, and a P-type confinement layer 30 stacked sequentially. (See reference...) Figure 2 The P-type confinement layer 30 includes an undoped layer 31 and a P-type doped layer 32 sequentially stacked on the active layer 20. The P-type doped layer 32 includes a first doped layer 321 and a second doped layer 322 alternately stacked on the undoped layer 31, wherein the P-type doping concentration of the first doped layer 321 is greater than the P-type doping concentration of the second doped layer 322.

[0050] See Figure 3 The barrier height of the P-type doped layer 30 is positively correlated with the P-type doping concentration. The P-type doping concentration of the first doped layer 321 is greater than that of the second doped layer 322. Therefore, the barrier of the first doped layer 321 is higher than that of the second doped layer 322.

[0051] In the aforementioned LED epitaxial structure, an N-type confinement layer 10, an active layer 20, and a P-type confinement layer 30 are stacked sequentially. The P-type confinement layer 30 includes an undoped layer 31 and a P-type doped layer 32 stacked sequentially. The P-type doped layer 32 includes an alternately stacked first doped layer 321 and a second doped layer 322. The P-type doping concentration of the first doped layer 321 is greater than that of the second doped layer 322. The higher P-type doping concentration of the first doped layer 321 can increase the potential barrier of the P-type confinement layer 30, effectively preventing fast-moving electrons from entering the P-type confinement layer 30 and recombinating with holes. This reduces the number of electrons overflowing from the active layer 20, increases the recombination probability of electrons and holes in the active layer 20, improves the internal quantum efficiency of the LED, and thus improves the luminous efficiency of the LED. Furthermore, the high P-type doping concentration of the first doped layer 321 increases the number of holes in the P-type confinement layer 30, which is beneficial for hole injection into the active layer 20 and recombination with electrons, further increasing the recombination probability of electrons and holes in the active layer 20, and ultimately improving the luminous efficiency of the LED. In addition, the second doped layer 322 with a lower P-type doping concentration is alternately stacked with the first doped layer 321, and an undoped layer 31 is provided between the P-type doped layer 32 and the active layer 20, which can effectively prevent P-type dopant from overflowing into the active layer 20 and affecting the recombination of electrons and holes in the active layer 20.

[0052] In some embodiments, the P-type doping concentration of the first doped layer 321 is 1.5 to 2.5 times that of the P-type doping concentration of the second doped layer 322.

[0053] Specifically, the P-type doping concentration of the first doped layer 321 can be 1.5 times, 1.8 times, 2 times, 2.2 times, or 2.5 times the P-type doping concentration of the second doped layer 322.

[0054] In the above embodiments, the P-type doping concentration of the first doped layer 321 is 0.5 to 1.5 times higher than that of the second doped layer 322, which can significantly increase the P-type doping concentration. On the one hand, this increases the potential barrier of the P-type confinement layer 30, preventing electrons from entering the P-type confinement layer 30; on the other hand, it increases the number of holes in the P-type confinement layer 30, which is beneficial for hole injection into the active layer 20. The two aspects combined increase the recombination probability of electrons and holes in the active layer 20, thereby improving the internal quantum efficiency of the LED and thus the luminous efficiency of the LED. Moreover, the P-type doping concentration is not increased indefinitely, which can prevent the P-type dopant from overflowing into the active layer 20 and causing adverse effects.

[0055] For example, the P-type doping concentration of the first doped layer 321 is 5.1E+17 to 9E+17, and the P-type doping concentration of the second doped layer 322 is 2.5E+17 to 4.5E+17.

[0056] Specifically, the P-type doping concentration of the first doped layer 321 is 5.1E+17, and the P-type doping concentration of the second doped layer 322 is 2.5E+17; or, the P-type doping concentration of the first doped layer 321 is 6E+17, and the P-type doping concentration of the second doped layer 322 is 3E+17; or, the P-type doping concentration of the first doped layer 321 is 7E+17, and the P-type doping concentration of the second doped layer 322 is 3.5E+17; or, the P-type doping concentration of the first doped layer 321 is 8E+17, and the P-type doping concentration of the second doped layer 322 is 4E+17; or, the P-type doping concentration of the first doped layer 321 is 9E+17, and the P-type doping concentration of the second doped layer 322 is 4.5E+17.

[0057] In practical applications, the P-type doping concentration of the P-type confinement layer 30 is typically 2.5E+17 to 4.5E+17. The P-type doping concentration of the first doped layer 321 is greater than that of the P-type confinement layer 30. Increasing the P-type doping concentration can, on the one hand, increase the potential barrier of the P-type confinement layer 30, preventing electrons from entering the P-type confinement layer 30, and on the other hand, increase the number of holes in the P-type confinement layer 30, which is beneficial for hole injection into the active layer 20. These two aspects combined improve the recombination probability of electrons and holes in the active layer 20, thereby improving the internal quantum efficiency of the LED and thus the luminous efficiency of the LED. Moreover, the P-type doping concentration of the second doped layer 322 is consistent with that of the P-type confinement layer 30, allowing for improvements based on the original structure of the P-type confinement layer 30. This improvement results in a better overall matching.

[0058] In some embodiments, the thickness of the first doped layer 321 is less than the thickness of the second doped layer 322.

[0059] In the above embodiments, the thickness of the first doped layer 321 is relatively small, which is beneficial to increasing the P-type doping concentration of the first doped layer 321, thereby ultimately improving the luminous efficiency of the LED by increasing the P-type doping concentration. The thickness of the second doped layer 322 is relatively large, which can effectively prevent the P-type doping concentration of the first doped layer 321 from being too high and overflowing into the active layer 20.

[0060] For example, the thickness ratio of the first doped layer 321 and the second doped layer 322 is equal to the P-type doping concentration ratio of the second doped layer 322 and the first doped layer 321.

[0061] In the above embodiment, the thickness ratio of the first doped layer 321 and the second doped layer 322 is equal to the P-type doping concentration ratio of the second doped layer 322 and the first doped layer 321. The P-type dopant in the P-type doped layer 32 is relatively stable, which makes it easy to control the P-type dopant in the P-type confinement layer 30 and avoid overflowing into the active layer 20.

[0062] For example, the thickness of the second doped layer 322 is 1.5 to 2.5 times the thickness of the first doped layer 321.

[0063] Specifically, the thickness of the second doped layer 322 can be 1.5 times, 1.8 times, 2 times, 2.2 times, or 2.5 times the thickness of the first doped layer 321.

[0064] With the P-type doping concentration of the first doped layer 321 being 0.5 to 1.5 times higher than that of the second doped layer 322, and the thickness of the second doped layer 322 being 0.5 to 1.5 times greater than that of the first doped layer 321, the two can work together.

[0065] Specifically, the P-type doping concentration of the first doped layer 321 is 1.5 times the P-type doping concentration of the second doped layer 322, and the thickness of the second doped layer 322 is 1.5 times the thickness of the first doped layer 321; or, the P-type doping concentration of the first doped layer 321 is twice the P-type doping concentration of the second doped layer 322, and the thickness of the second doped layer 322 is twice the thickness of the first doped layer 321; or, the P-type doping concentration of the first doped layer 321 is 2.5 times the P-type doping concentration of the second doped layer 322, and the thickness of the second doped layer 322 is 2.5 times the thickness of the first doped layer 321.

[0066] In some embodiments, the thickness of the undoped layer 31 is less than the thickness of the p-type doped layer 32.

[0067] In the above embodiments, the P-type doped layer 32 has a larger thickness and provides a greater number of holes, which is beneficial for the recombination of holes with electrons in the active layer 20, ensuring the recombination probability of electrons and holes in the active layer 20, and ultimately improving the luminous efficiency of the LED.

[0068] For example, the thickness of the P-type doped layer 32 is 3 to 5 times the thickness of the undoped layer 31.

[0069] Specifically, the thickness of the P-type doped layer 32 can be 3 times, 3.5 times, 4 times, 4.5 times, or 5 times the thickness of the undoped layer 31.

[0070] In the above embodiments, the thickness of the P-type doped layer 32 is 2 to 4 times greater than the thickness of the undoped layer 31. The P-type confinement layer 30 as a whole can provide a sufficient number of holes for injection into the active layer 20, while the undoped layer 31 can prevent the P-type dopant from overflowing into the active layer 20.

[0071] For example, the thickness of the undoped layer 31 is 0.05 μm to 0.2 μm, and the thickness of the p-type doped layer 32 is 0.25 μm to 0.8 μm.

[0072] Specifically, the thickness of the undoped layer 31 is 0.1 μm and the thickness of the p-type doped layer 32 is 0.4 μm; or, the thickness of the undoped layer 31 is 0.12 μm and the thickness of the p-type doped layer 32 is 0.48 μm; or, the thickness of the undoped layer 31 is 0.14 μm and the thickness of the p-type doped layer 32 is 0.56 μm; or, the thickness of the undoped layer 31 is 0.16 μm and the thickness of the p-type doped layer 32 is 0.64 μm; or, the thickness of the undoped layer 31 is 0.18 μm and the thickness of the p-type doped layer 32 is 0.72 μm; or, the thickness of the undoped layer 31 is 0.2 μm and the thickness of the p-type doped layer 32 is 0.8 μm.

[0073] In the above embodiments, the thickness of the undoped layer 31 is 0.05 μm to 0.2 μm, the thickness of the P-type doped layer 32 is 0.25 μm to 0.8 μm, and the thickness of the P-type confinement layer 30 is 0.3 μm to 1 μm.

[0074] In some embodiments, the P-type doped layer 32 includes a plurality of periods, each period including a first doped layer 321 and a second doped layer 322 stacked on the first doped layer 321.

[0075] In the above embodiment, the first doped layer 321 of the same period is closer to the undoped layer 31 than the second doped layer 322. The first doped layer 321 is located between the undoped layer 31 and the second doped layer 322, which helps to prevent the P-type dopant from overflowing the P-type confinement layer 30.

[0076] For example, the P-type doped layer 32 includes at least two periods.

[0077] Specifically, the P-type doped layer 32 may include 2 periods, 3 periods, 4 periods, 5 periods, 6 periods, 7 periods, or 8 periods.

[0078] In the above embodiments, the P-type doped layer 32 includes at least two periods, each period including a first doped layer 321 and a second doped layer 322 stacked on the first doped layer 321. The first doped layer 321 and the second doped layer 322 are stacked alternately, which is beneficial for hole injection into the active layer 20, while avoiding the overflow of P-type dopant from the active layer 20.

[0079] Specifically, the undoped layer 31 is an undoped AlGaP layer, specifically Al 0.5 Ga 0.5 P-layer. The first doped layer 321 and the second doped layer 322 are P-type doped AlGaP layers, specifically Al 0.5 Ga 0.5 P-layer. The P-type dopant is Mg.

[0080] The N-type confinement layer 10 is an N-type doped AlGaP layer, specifically Al0.5 Ga 0.5 The thickness of the P-layer and the N-type confinement layer 10 is 0.25 μm to 0.45 μm, such as 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, and 0.45 μm.

[0081] See Figure 4 In some embodiments, the active layer 20 includes a quantum well layer 21 and a quantum barrier layer 22 alternately stacked on the N-type confinement layer 10.

[0082] Specifically, both quantum well layer 21 and quantum barrier layer 22 are undoped AlGaInP layers, and the composition contents of quantum well layer 21 and quantum barrier layer 22 are different. For example, the content of Al component in quantum well layer 21 is less than the content of Al component in quantum barrier layer 22, and the content of Ga component in quantum well layer 21 is less than the content of Ga component in quantum barrier layer 22.

[0083] The thickness of the active layer 20 is 0.2μm to 0.3μm, such as 0.2μm, 0.22μm, 0.24μm, 0.26μm, 0.28μm, and 0.3μm.

[0084] like Figure 4 As shown, in one implementation, when the quantum well layer 21 in the active layer 20 is in contact with the N-type confinement layer 10, the LED epitaxial structure further includes a first waveguide layer 23, which is disposed between the N-type confinement layer 10 and the active layer 20.

[0085] Specifically, the first waveguide layer 23 is an undoped AlGaInP layer, and the thickness of the first waveguide layer 23 is 0.06μm to 0.1μm, such as 0.06μm, 0.07μm, 0.08μm, 0.09μm, or 0.1μm.

[0086] like Figure 4 As shown, in another implementation, when the quantum well layer 21 in the active layer 20 contacts the P-type confinement layer 30, the LED epitaxial structure also includes a second waveguide layer 24, which is disposed between the active layer 20 and the P-type confinement layer 30.

[0087] Specifically, the second waveguide layer 24 is an undoped AlGaInP layer, and the thickness of the second waveguide layer 24 is 0.07μm to 0.1μm, such as 0.07μm, 0.08μm, 0.09μm, and 0.1μm.

[0088] like Figure 1As shown, in some embodiments, the LED epitaxial structure further includes a substrate 40, with an N-type confinement layer 10, an active layer 20, and a P-type confinement layer 30 sequentially stacked on the substrate 40. The substrate 40 provides a growth surface for the N-type confinement layer 10, the active layer 20, and the P-type confinement layer 30, and also serves as a support.

[0089] Specifically, substrate 40 is a GaAs substrate.

[0090] like Figure 1 As shown, in some embodiments, the LED epitaxial structure further includes a buffer layer 50 disposed between the substrate 40 and the N-type confinement layer 10. The buffer layer 50 facilitates the growth of a high-quality N-type confinement layer 10 on the substrate 40.

[0091] Specifically, the buffer layer 50 is a GaAs layer with a thickness of 0.4μm to 0.6μm, such as 0.4μm, 0.45μm, 0.5μm, 0.55μm, or 0.6μm.

[0092] like Figure 1 As shown, in some embodiments, the LED epitaxial structure further includes a reflective layer 60, which is disposed between the buffer layer 50 and the N-type confinement layer 10. The reflective layer 60 can reflect light incident on the substrate 40, thereby improving the front-side light emission efficiency of the LED.

[0093] Specifically, the reflective layer 60 is a distributed Bragg reflector (DBR). The reflective layer 60 includes a first reflective layer and a second reflective layer alternately stacked on the buffer layer 50, where the reflectivity of the first reflective layer is less than that of the second reflective layer. For example, the first reflective layer is an AlAs layer, and the second reflective layer is an AlGaAs layer. Optionally, the reflective layer 60 includes multiple periodic structures stacked sequentially, each periodic structure including a first reflective layer and a second reflective layer stacked on top of the first reflective layer.

[0094] The thickness of the reflective layer 60 is 2μm to 4μm, such as 2μm, 2.5μm, 3μm, 3.5μm, and ~4μm.

[0095] like Figure 1 As shown, in some embodiments, the LED epitaxial structure further includes a current spreading layer 70, which is disposed on the surface of the P-type confinement layer 30 away from the active layer 20. The current spreading layer 70 facilitates uniform current injection into the P-type confinement layer 30.

[0096] Specifically, the current spreading layer 70 is a P-type doped GaP layer, and the thickness of the current spreading layer 70 is 5μm to 6μm, such as 5μm, 5.2μm, 5.4μm, 5.6μm, 5.8μm, and 6μm.

[0097] like Figure 1 As shown, in some embodiments, the LED epitaxial structure further includes a transition layer 80, which is disposed between the P-type confinement layer 30 and the current spreading layer 70.

[0098] Specifically, the material of the transition layer 80 transitions from AlGaInP to GaInP, and the thickness of the transition layer 80 is 0.04μm to 0.08μm, such as 0.04μm, 0.05μm, 0.06μm, 0.07μm, and 0.08μm.

[0099] Based on the same inventive concept, this application also provides an LED device (not shown in the figure), which includes an N-type electrode, a P-type electrode, and the LED epitaxial structure provided in the above embodiments. The N-type electrode is disposed on an N-type confinement layer, and the P-type electrode is disposed on a P-type confinement layer.

[0100] Based on the same inventive concept, see [link / reference] Figure 5 This application also provides a method for fabricating an LED epitaxial structure, the method comprising the following steps:

[0101] Step S502, provide a substrate.

[0102] Specifically, step S502 includes:

[0103] The temperature of the reaction chamber is controlled at 650℃~750℃, and hydrogen is used to purge the substrate to remove water vapor in the reaction chamber through high-temperature treatment.

[0104] Step S504: An N-type confinement layer and an active layer are sequentially grown on the substrate.

[0105] Specifically, step S504 includes:

[0106] An N-type confinement layer and an active layer are sequentially grown on a substrate using metal-organic chemical vapor deposition (MOCVD) technology.

[0107] Optionally, before step S504, the method further includes:

[0108] A buffer layer and a reflective layer are grown sequentially on the substrate.

[0109] Step S506: Grow an undoped layer on the active layer.

[0110] Specifically, step S506 includes:

[0111] Undoped layers are grown on active layers using MOCVD technology.

[0112] In step S508, a first doped layer and a second doped layer are alternately grown on the undoped layer to form a P-type doped layer. The P-type doped layer and the undoped layer form a P-type confinement layer. The P-type doping concentration of the first doped layer is greater than that of the second doped layer.

[0113] Specifically, step S508 includes:

[0114] The MOCVD technique is used to alternately grow the first doped layer and the second doped layer on the undoped layer.

[0115] Optionally, the concentration of P-type doping can be changed by altering the amount of Mg introduced into the reaction chamber.

[0116] Optionally, after step S508, the method further includes:

[0117] A transition layer and a current spreading layer are grown sequentially on the P-type confinement layer.

[0118] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An LED epitaxial structure, characterized in that, include: N-type confinement layer; An active layer is stacked on the N-type confinement layer; as well as The P-type confinement layer includes an undoped layer and a P-type doped layer sequentially stacked on the active layer. The P-type doped layer includes a first doped layer and a second doped layer alternately stacked on the undoped layer. The P-type doping concentration of the first doped layer is greater than that of the second doped layer. The barrier of the first doped layer is higher than that of the second doped layer to prevent fast-moving electrons from entering the P-type confinement layer and recombinating with holes; The thickness ratio of the first doped layer to the second doped layer is equal to the P-type doping concentration ratio of the second doped layer to the first doped layer; The P-type doped layer includes multiple periods, each period including the first doped layer and the second doped layer stacked on the first doped layer.

2. The LED epitaxial structure as described in claim 1, characterized in that, The P-type doping concentration of the first doped layer is 1.5 to 2.5 times that of the P-type doping concentration of the second doped layer.

3. The LED epitaxial structure as described in claim 2, characterized in that, The P-type doping concentration of the first doped layer is 5.1E+17 to 9E+17, and the P-type doping concentration of the second doped layer is 2.5E+17 to 4.5E+17.

4. The LED epitaxial structure according to any one of claims 1-3, characterized in that, The thickness of the first doped layer is less than the thickness of the second doped layer.

5. The LED epitaxial structure as described in claim 4, characterized in that, The thickness of the second doped layer is 1.5 to 2.5 times the thickness of the first doped layer.

6. The LED epitaxial structure according to any one of claims 1-3, characterized in that, The thickness of the P-type doped layer is 3 to 5 times the thickness of the undoped layer.

7. An LED device, characterized in that, It includes an N-type electrode, a P-type electrode, and an LED epitaxial structure as described in any one of claims 1-6, wherein the N-type electrode is disposed on the N-type confinement layer, and the P-type electrode is disposed on the P-type confinement layer.

8. A method for fabricating an LED epitaxial structure, characterized in that, The step of implementing an LED epitaxial structure as described in any one of claims 1-6 includes: Provide substrate; An N-type confinement layer and an active layer are sequentially grown on the substrate; An undoped layer is grown on the active layer; A first doped layer and a second doped layer are alternately grown on the undoped layer to form a P-type doped layer. The P-type doped layer and the undoped layer form a P-type confinement layer. The P-type doping concentration of the first doped layer is greater than that of the second doped layer.

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