Light emitting diode epitaxial wafer and preparation method thereof, LED

Abstract

This invention relates to the field of optoelectronic technology, and discloses a light-emitting diode epitaxial wafer and its fabrication method, as well as an LED. The light-emitting diode epitaxial wafer includes a substrate, on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed. The stress relief layer includes sequentially stacked In... x Ga 1‑x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1‑z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1‑y The invention comprises an N-layer and a first GaN layer, wherein the values ​​of x range from 0.01 to 0.2, y range from 0.1 to 0.5, and z range from 0.01 to 0.2. The epitaxial wafer for a light-emitting diode provided by this invention improves the luminous efficiency of the diode and reduces forward and reverse leakage current.

Description

Technical Field

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

[0002] With the improvement of various performance aspects of light-emitting diodes (LEDs), LEDs have gradually replaced incandescent lamps as the next generation of lighting products, and are widely used in smart lighting, architectural lighting, communications, and security. GaN-based LEDs with a multi-quantum-well structure as the main light-emitting layer have high radiative recombination efficiency, becoming a core technology in the semiconductor field in recent years. Their growth method mainly involves the periodic alternation of two materials with different bandgap widths, InGaN and GaN. InGaN has a smaller bandgap than GaN, making it easier for electrons to be confined in the smaller bandgap quantum well layer during the transport of electrons from N-type to P-type semiconductors, leading to radiative recombination with holes. Therefore, the InGaN / GaN multi-quantum-well structure plays a role in confining charge carriers and improving radiative recombination efficiency. However, due to the poor lattice constant matching between InGaN and GaN, a large strain-polarized electric field is generated, resulting in severe bandgap tilt and a significant overflow phenomenon that exacerbates luminous efficiency degradation.

[0003] To reduce the piezoelectric polarization effect caused by lattice mismatch and effectively release stress in the quantum well region, a low-In-content InGaN / GaN quantum well preparation layer or an InGaN / GaN superlattice preparation layer is typically grown before the quantum well layer. However, a simple InGaN / GaN quantum well preparation layer or InGaN / GaN superlattice preparation layer suffers from severe In segregation due to factors such as the extension of underlying defects or growth temperature mismatch, resulting in degraded crystal quality. Simultaneously, the uneven stress-relieving layer further degrades the crystal quality of the subsequently grown quantum well layer, with defects penetrating into multiple quantum well layers, increasing the probability of nonradiative recombination in these layers and ultimately leading to a decrease in internal quantum efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an epitaxial wafer for a light-emitting diode that improves the luminous efficiency of the diode and reduces forward and reverse leakage current.

[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 has a simple process and can stably produce an epitaxial wafer of a light-emitting diode with good luminous efficiency.

[0006] To solve the above-mentioned technical problems, the present invention provides a light-emitting diode epitaxial wafer, including a substrate, wherein a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed on the substrate.

[0007] The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, wherein the value of x ranges from 0.01 to 0.2, the value of y ranges from 0.1 to 0.5, and the value of z ranges from 0.01 to 0.2.

[0008] In some embodiments, the thickness of the stress relief layer is 100 nm to 800 nm.

[0009] In some implementations, the In x Ga 1-x Thickness of N / GaN superlattice layer: Thickness of highly doped N-type GaN layer: Thickness of multi-quantum-well structure layer: Thickness of undoped Al z Ga 1-z The thickness of layer N = (4-6):1:(2-4):1.

[0010] In some implementations, the In x Ga 1-x The N / GaN superlattice layer consists of alternating layers of In. x Ga 1-x The N-layer and the second GaN-layer have a period number of 10 to 50.

[0011] In some implementations, the In x Ga 1-x The thickness difference between the N layer and the second GaN layer does not exceed 5 nm.

[0012] In some embodiments, the multi-quantum-well structure layer comprises alternating layers of In y Ga 1-y The N-layer and the first GaN layer have a period number of 2 to 10.

[0013] In some embodiments, the first GaN layer is an N-type doped GaN layer, and the doping concentration of the N-type dopant is 1×10⁻⁶. 17 atoms / cm 3 ~1×10 18 atoms / cm 3 ;

[0014] The In y Ga 1-y Thickness of N layer: Thickness of the first GaN layer = 1:(3~6).

[0015] In some embodiments, the doping concentration of the N-type dopant in the highly doped N-type GaN layer is 1 × 10⁻⁶. 18 atoms / cm 3 ~1×10 19 atoms / cm 3 .

[0016] To address the above problems, the present invention also provides a method for fabricating a light-emitting diode epitaxial wafer, comprising the following steps:

[0017] S1, Provide a substrate;

[0018] S2. Sequentially deposit a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer, and a P-type GaN layer on the substrate.

[0019] The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, wherein the value of x ranges from 0.01 to 0.2, the value of y ranges from 0.1 to 0.5, and the value of z ranges from 0.01 to 0.2.

[0020] Accordingly, the present invention also provides an LED, the LED comprising a light-emitting diode epitaxial wafer as described above, or comprising a light-emitting diode epitaxial wafer prepared by the method for preparing a light-emitting diode epitaxial wafer as described above.

[0021] Implementing this invention has the following beneficial effects:

[0022] The LED epitaxial wafer provided by this invention includes a superlattice structure and a multi-quantum well structure in its stress relief layer. This effectively avoids problems such as the deterioration of crystal quality due to underlying defects or severe In segregation caused by factors such as growth temperature mismatch. Specifically, In... x Ga 1-x Due to its lower In content, the N / GaN superlattice layer exhibits better crystal quality compared to multi-quantum wells, and effectively suppresses In segregation in subsequent multi-quantum well layers, providing a high-quality growth substrate for the multi-quantum well layer. The multi-quantum well structure layer comprises alternating layers of In... y Ga 1-yThe N-layer and the first GaN layer can provide favorable conditions for the epitaxial structure to form V-shaped defects, thereby increasing the efficiency of hole injection from the sidewalls of the V-shaped defects. On the other hand, the multi-quantum well structure layer is similar to the multi-quantum well light-emitting layer structure, which can release the compressive stress of the multi-quantum well light-emitting layer, reduce the band tilt caused by stress polarization, increase the probability of electron-hole overlap, and improve the light efficiency.

[0023] The present invention is described in In x Ga 1-x A highly doped N-type GaN layer is inserted after the N / GaN superlattice layer as a polarization modulation layer, and an undoped Al layer is inserted after the multi-quantum-well structure layer. z Ga 1-z The N-layer serves as a defect shielding layer. The N-type doping concentration of the highly doped N-type GaN layer is higher than that of the multi-quantum-well structure layer, allowing its built-in electric field to effectively counteract the QCSE effect caused by piezoelectric polarization and effectively eliminate In... x Ga 1-x The heterojunction barrier between the N / GaN superlattice layer and the multi-quantum-well structure layer reduces the operating voltage.

[0024] In addition, when the highly doped N-type GaN layer grows along the V-shaped sidewall, the thickness near the bottom of the V-shaped pit is greater than that of the V-shaped sidewall. The potential energy at the bottom of the V-shaped pit is higher than that of the sidewall, making it easier for holes to be injected into the light-emitting trap region from the V-shaped opening near the P side, thus improving the luminescence efficiency.

[0025] Furthermore, undoped Al z Ga 1-z In the N-layer, Al atoms, due to their small lattice constant and low mobility, can fully fill the deep-level defects caused by lattice mismatch in the multi-quantum-well light-emitting layer, reducing the forward leakage rate and increasing the turn-on voltage. Meanwhile, undoped Al atoms... z Ga 1-z The N-layer can effectively block the overshoot of electrons from the N-side into the multi-quantum-well light-emitting layer, which would lead to uneven carrier distribution and Auger recombination. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the light-emitting diode epitaxial wafer provided by the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Furthermore, it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "left", "right", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0032] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0033] In this invention, "preferred" and "more preferred" are merely descriptions of better implementation methods or embodiments, and should be understood as not constituting a limitation on the scope of protection of this invention. In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features. In this invention, numerical ranges are involved; unless otherwise specified, they include the two endpoints of the numerical range.

[0034] To address the above problems, the present invention provides a light-emitting diode epitaxial wafer, such as... Figure 1 As shown, the substrate includes a substrate 100, on which a buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, a stress relief layer 500, a multi-quantum-well light-emitting layer 600, an electron blocking layer 700, and a P-type GaN layer 800 are sequentially disposed.

[0035] The stress relief layer 500 comprises In layers stacked sequentially. x Ga 1-x The structure consists of an N / GaN superlattice layer 510, a highly doped N-type GaN layer 520, a multi-quantum-well structure layer 530, and an undoped Al layer. z Ga 1-z N-layer 540, the multi-quantum-well structure layer 530 includes alternating layers of In y Ga 1-y The N layer and the first GaN layer, wherein the value of x ranges from 0.01 to 0.2, the value of y ranges from 0.1 to 0.5, and the value of z ranges from 0.01 to 0.2.

[0036] The specific structure of the stress relief layer 500 provided by the present invention is as follows:

[0037] In some embodiments, the thickness of the stress relief layer 500 is 100nm to 800nm. Exemplary thicknesses of the stress relief layer 500 are 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, and 750nm, but are not limited to the above examples. In some embodiments, the In... x Ga 1-x Thickness of N / GaN superlattice layer 510: Thickness of highly doped N-type GaN layer 520: Thickness of multi-quantum-well structure layer 530: Thickness of undoped Al z Ga 1-z The thickness of layer N (540) is (4-6):1:(2-4):1. For example, the In... x Ga 1-x Thickness of N / GaN superlattice layer 510: Thickness of highly doped N-type GaN layer 520: Thickness of multi-quantum-well structure layer 530: Thickness of undoped Al z Ga 1-z The thickness of layer N (540) is (4:1:2:1), (4:1:3:1), (4:1:4:1), (5:1:2:1), (5:1:3:1), (5:1:4:1), (6:1:2:1), (6:1:3:1), (6:1:4:1), and is not limited to the above list.

[0038] In some embodiments, the In x Ga 1-x The N / GaN superlattice layer 510 includes alternating layers of In. x Ga 1-x The N-layer and the second GaN layer have a period number of 10 to 50; exemplary period numbers are 15, 20, 25, 30, 35, 40, and 45, but are not limited to the above examples. Preferably, the In... x Ga 1-x The thickness difference between the N-layer and the second GaN-layer does not exceed 5 nm. x Ga 1-x Due to its lower In content, the N / GaN superlattice layer has better crystal quality than the multi-quantum well layer and effectively suppresses the In segregation phenomenon in the subsequent multi-quantum well layer, providing a growth substrate with better crystal quality for the multi-quantum well layer.

[0039] In some embodiments, the doping concentration of the N-type dopant in the highly doped N-type GaN layer 520 is 1 × 10⁻⁶. 18 atoms / cm 3 ~1×10 19 atoms / cm 3The exemplary N-type dopant concentration of the highly doped N-type GaN layer 520 is 2 × 10⁻⁶. 18 atoms / cm 3 3×10 18 atoms / cm 3 4×10 18 atoms / cm 3 5×10 18 atoms / cm 3 6×10 18 atoms / cm 3 7×10 18 atoms / cm 3 8×10 18 atoms / cm 3 9×10 18 atoms / cm 3 However, it is not limited to the examples listed above. In the In x Ga 1-x A highly doped N-type GaN layer 520 is inserted after the N / GaN superlattice layer 510 as a polarization modulation layer. The N-type doping concentration of the highly doped N-type GaN layer 520 is higher than that of the subsequent multi-quantum-well structure layer 530, which allows its built-in electric field strength to fully counteract the QCSE effect caused by piezoelectric polarization and effectively eliminate the In x Ga 1-x The heterojunction barrier between the N / GaN superlattice layer 510 and the multi-quantum-well structure layer 530 reduces the operating voltage. Furthermore, when the highly doped N-type GaN layer 520 grows along the V-shaped sidewalls, its thickness near the bottom of the V-shaped pit is greater than that of the sidewalls. The potential energy at the bottom of the V-shaped pit is higher than that of the sidewalls, making it easier for holes to be injected into the light-emitting well region from the V-shaped opening near the P-side, thus improving luminous efficiency.

[0040] In some embodiments, the multi-quantum-well structure layer 530 includes alternating layers of In y Ga 1-y The N layer and the first GaN layer have a period number of 2 to 10; exemplary period numbers are 3, 4, 5, 6, 7, 8, and 9, but are not limited to the above list.

[0041] In some embodiments, the first GaN layer is an N-type doped GaN layer, and the doping concentration of the N-type dopant is 1×10⁻⁶. 17 atoms / cm 3 ~1×10 18 atoms / cm 3 The exemplary N-type dopant concentration of the first GaN layer is 2 × 10⁻⁶. 17 atoms / cm 3 3×1017 atoms / cm 3 4×10 17 atoms / cm 3 5×10 17 atoms / cm 3 6×10 17 atoms / cm 3 7×10 17 atoms / cm 3 8×10 17 atoms / cm 3 9×10 17 atoms / cm 3 However, this is not limited to the examples listed above. The N-type doping concentration of the first GaN layer is lower than that of the highly doped N-type GaN layer 520, which allows its built-in electric field strength to fully counteract the QCSE effect caused by piezoelectric polarization, and effectively eliminates In... x Ga 1-x The heterojunction barrier between the N / GaN superlattice layer 510 and the multi-quantum well structure layer 530 reduces the operating voltage.

[0042] In some implementations, the In y Ga 1-y The thickness of the N layer: the thickness of the first GaN layer = 1:(3~6). For example, the In... y Ga 1-y The thickness of the N layer: The thickness of the first GaN layer = (1:3), (1:4), (1:5), (1:6), but not limited to the above examples. The multi-quantum-well structure layer 530 includes alternating layers of In. y Ga 1-y The N-layer and the first GaN layer can provide favorable conditions for the epitaxial structure to form V-shaped defects, thereby increasing the efficiency of hole injection from the sidewalls of the V-shaped defects. On the other hand, the multi-quantum well structure layer is similar to the multi-quantum well light-emitting layer structure, which can release the compressive stress of the multi-quantum well light-emitting layer, reduce the band tilt caused by stress polarization, increase the probability of electron-hole overlap, and improve the light efficiency.

[0043] Finally, undoped Al was inserted after the multi-quantum-well structure layer 530. z Ga 1-z N-layer 540 serves as a defect shielding layer. Undoped Al z Ga 1-z In the N-layer, Al atoms, due to their small lattice constant and low mobility, can fully fill the deep-level defects caused by lattice mismatch in the multi-quantum-well light-emitting layer, reducing the forward leakage rate and increasing the turn-on voltage. Meanwhile, undoped Al atoms... z Ga 1-zThe N-layer can effectively block the overshoot of electrons from the N-side into the multi-quantum-well light-emitting layer, which would lead to uneven carrier distribution and Auger recombination.

[0044] In summary, the stress relief layer of the light-emitting diode epitaxial wafer provided by this invention includes a superlattice structure and a multi-quantum-well structure, which can effectively avoid the problems of deterioration in crystal quality due to underlying defects or severe In segregation caused by factors such as growth temperature mismatch. Furthermore, in the In... x Ga 1-x A highly doped N-type GaN layer is inserted after the N / GaN superlattice layer as a polarization modulation layer, and an undoped Al layer is inserted after the multi-quantum-well structure layer. z Ga 1-z The N-layer acts as a defect shielding layer. The combined effect of these four sub-layers improves the diode's luminous efficiency and reduces forward and reverse leakage current.

[0045] Accordingly, the present invention provides a method for fabricating a light-emitting diode epitaxial wafer, comprising the following steps:

[0046] S1. Provide substrate 100;

[0047] In some embodiments, the substrate 100 may be selected from one of the following: sapphire substrate, SiO2-sapphire composite substrate, silicon substrate, silicon carbide substrate, gallium nitride substrate, and zinc oxide substrate. Preferably, the substrate 100 is a sapphire substrate. Sapphire is a commonly used GaN-based LED substrate material. Sapphire substrates have mature manufacturing processes, low prices, are easy to clean and process, and have good stability at high temperatures.

[0048] S2. A buffer layer 200, an undoped GaN layer 300, an N-type GaN layer 400, a stress relief layer 500, a multi-quantum-well light-emitting layer 600, an electron blocking layer 700, and a P-type GaN layer 800 are sequentially deposited on the substrate 100.

[0049] The stress relief layer 500 comprises In layers stacked sequentially. x Ga 1-x The structure consists of an N / GaN superlattice layer 510, a highly doped N-type GaN layer 520, a multi-quantum-well structure layer 530, and an undoped Al layer. z Ga 1-z N-layer 540, the multi-quantum-well structure layer 530 includes alternating layers of In y Ga 1-y The N layer and the first GaN layer, wherein the value of x ranges from 0.01 to 0.2, the value of y ranges from 0.1 to 0.5, and the value of z ranges from 0.01 to 0.2.

[0050] Specifically, step S2 above includes the following steps:

[0051] S21. Deposit the buffer layer 200 on the substrate 100.

[0052] In some embodiments, the buffer layer 200 is an AlN buffer layer.

[0053] S22. Deposit the undoped GaN layer 300 on the buffer layer 200.

[0054] In some embodiments, the temperature of the reaction chamber is controlled at 1000℃~1200℃, the pressure is controlled at 100torr~600torr, and an N source and a Ga source are introduced to grow an undoped GaN layer with a thickness of 1μm~5μm.

[0055] S23. Deposit the N-type GaN layer 400 on the undoped GaN layer 300.

[0056] In some embodiments, the temperature of the reaction chamber is controlled at 1000℃~1200℃, the pressure is controlled at 100torr~600torr, and an N source, a Ga source, and a Si source are introduced to grow the N-type GaN layer.

[0057] S24. Deposit the stress relief layer 500 on the N-type GaN layer 400.

[0058] In some embodiments, the In x Ga 1-x The growth rate of the N / GaN superlattice layer 510 is greater than that of the multi-quantum-well structure layer 530. This effectively controls the morphology of large V-shaped pits and reduces the number of small V-shaped pits that affect crystal quality. x Ga 1-x The N / GaN superlattice layer 510 is a fast-growing layer. This rapid growth makes it easier for dislocations to evolve into V-shaped defects, thus becoming the starting point for V-shaped pits. These V-shaped pits can then extend throughout the entire light-emitting layer, and larger V-shaped pits can effectively shield dislocations and improve hole injection efficiency. The decelerated growth of the multi-quantum-well structure layer 530 effectively avoids the formation of small defects in the GaN layer, reducing leakage channels and improving product yield.

[0059] S25. Deposit the multi-quantum-well light-emitting layer 600 on the stress-relieving layer 500.

[0060] In some embodiments, the multi-quantum-well light-emitting layer is an alternating stack of InGaN quantum well layers and AlGaN quantum barrier layers, with a stacking period of 1 to 20. The growth temperature of the InGaN quantum well layer is 750°C to 880°C, the thickness is 2nm to 5nm, and the growth pressure is 50 torr to 300 torr. The growth temperature of the AlGaN quantum barrier layer is 800°C to 900°C, the thickness is 5nm to 15nm, and the growth pressure is 50 torr to 300 torr.

[0061] S26. Deposit the electron blocking layer 700 on the multi-quantum-well light-emitting layer 600;

[0062] In some embodiments, the temperature of the reaction chamber is controlled at 900°C to 1000°C, the pressure is controlled at 100 torr to 300 torr, and N source, Al source, Ga source, and In source are introduced to grow an AlInGaN electron blocking layer with a thickness of 10 nm to 40 nm.

[0063] S27. Deposit the P-type GaN layer 800 on the electron blocking layer 700.

[0064] In some embodiments, the temperature of the reaction chamber is controlled at 900°C to 1050°C, the pressure is controlled at 100 torr to 600 torr, and an N source, a Mg source, and a Ga source are introduced to grow the P-type GaN layer.

[0065] Accordingly, the present invention also provides an LED comprising the aforementioned light-emitting diode epitaxial wafer. The photoelectric efficiency of the LED is effectively improved, and other electrical properties are also excellent.

[0066] The present invention is further illustrated below with specific embodiments:

[0067] Example 1

[0068] This embodiment provides a light-emitting diode epitaxial wafer, including a substrate, on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed;

[0069] The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, where x takes the value of 0.015, y takes the value of 0.15, and z takes the value of 0.12.

[0070] The In x Ga 1-x Thickness of N / GaN superlattice layer: Thickness of highly doped N-type GaN layer: Thickness of multi-quantum-well structure layer: Thickness of undoped Al z Ga 1-z The thickness of layer N is 4:1:4:1.

[0071] The In x Ga 1-x The N / GaN superlattice layer consists of alternating layers of In. x Ga 1-x The N-layer and the second GaN-layer have a period number of 25.

[0072] The multi-quantum-well structure layer includes alternating layers of In y Ga 1-y The N-layer and the first GaN layer have a cycle number of 5.

[0073] The doping concentration of the N-type dopant in the highly doped N-type GaN layer is 1×10⁻⁶. 18 atoms / cm 3 The doping concentration of the N-type dopant in the first GaN layer is 1×10⁻⁶. 17 atoms / cm 3 .

[0074] Example 2

[0075] This embodiment provides a light-emitting diode epitaxial wafer, including a substrate, on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed;

[0076] The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, where x takes the value of 0.015, y takes the value of 0.15, and z takes the value of 0.12.

[0077] The In x Ga 1-x Thickness of N / GaN superlattice layer: Thickness of highly doped N-type GaN layer: Thickness of multi-quantum-well structure layer: Thickness of undoped Al z Ga 1-zThe thickness of layer N is 4:1:4:1.

[0078] The In x Ga 1-x The N / GaN superlattice layer consists of alternating layers of In. x Ga 1-x The N-layer and the second GaN-layer have a period number of 25.

[0079] The multi-quantum-well structure layer includes alternating layers of In y Ga 1-y The N-layer and the first GaN layer have a period of 6.

[0080] The doping concentration of the N-type dopant in the highly doped N-type GaN layer is 1×10⁻⁶. 18 atoms / cm 3 The doping concentration of the N-type dopant in the first GaN layer is 1×10⁻⁶. 17 atoms / cm 3 .

[0081] Example 3

[0082] This embodiment provides a light-emitting diode epitaxial wafer, including a substrate, on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed;

[0083] The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, where x takes the value of 0.018, y takes the value of 0.18, and z takes the value of 0.12.

[0084] The In x Ga 1-x Thickness of N / GaN superlattice layer: Thickness of highly doped N-type GaN layer: Thickness of multi-quantum-well structure layer: Thickness of undoped Al z Ga 1-z The thickness of layer N is 4:1:4:1.

[0085] The In x Ga 1-x The N / GaN superlattice layer consists of alternating layers of In. x Ga 1-x The N-layer and the second GaN-layer have a period number of 25.

[0086] The multi-quantum-well structure layer includes alternating layers of In y Ga 1-y The N-layer and the first GaN layer have a cycle number of 5.

[0087] The doping concentration of the N-type dopant in the highly doped N-type GaN layer is 1×10⁻⁶. 18 atoms / cm 3 The doping concentration of the N-type dopant in the first GaN layer is 1×10⁻⁶. 17 atoms / cm 3 .

[0088] Example 4

[0089] This embodiment provides a light-emitting diode epitaxial wafer, including a substrate, on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed;

[0090] The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, where x takes the value of 0.015, y takes the value of 0.15, and z takes the value of 0.15.

[0091] The In x Ga 1-x Thickness of N / GaN superlattice layer: Thickness of highly doped N-type GaN layer: Thickness of multi-quantum-well structure layer: Thickness of undoped Al z Ga 1-z The thickness of layer N is 4:1:4:1.

[0092] The In x Ga 1-x The N / GaN superlattice layer consists of alternating layers of In. x Ga 1-x The N-layer and the second GaN-layer have a period number of 25.

[0093] The multi-quantum-well structure layer includes alternating layers of In y Ga 1-y The N-layer and the first GaN layer have a cycle number of 5.

[0094] The doping concentration of the N-type dopant in the highly doped N-type GaN layer is 1×10⁻⁶.18 atoms / cm 3 The doping concentration of the N-type dopant in the first GaN layer is 1×10⁻⁶. 17 atoms / cm 3 .

[0095] Example 5

[0096] This embodiment provides a light-emitting diode epitaxial wafer, including a substrate, on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed;

[0097] The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, where x takes the value of 0.015, y takes the value of 0.15, and z takes the value of 0.12.

[0098] The In x Ga 1-x Thickness of N / GaN superlattice layer: Thickness of highly doped N-type GaN layer: Thickness of multi-quantum-well structure layer: Thickness of undoped Al z Ga 1-z The thickness of layer N is 4:1:4:1.

[0099] The In x Ga 1-x The N / GaN superlattice layer consists of alternating layers of In. x Ga 1-x The N-layer and the second GaN-layer have a period number of 25.

[0100] The multi-quantum-well structure layer includes alternating layers of In y Ga 1-y The N-layer and the first GaN layer have a cycle number of 5.

[0101] The doping concentration of the N-type dopant in the highly doped N-type GaN layer is 5 × 10⁻⁶. 18 atoms / cm 3 The doping concentration of the N-type dopant in the first GaN layer is 5 × 10⁻⁶. 17 atoms / cm 3 .

[0102] Example 6

[0103] This embodiment provides a light-emitting diode epitaxial wafer, including a substrate, on which a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multiple quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially disposed;

[0104] The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, where x takes the value of 0.015, y takes the value of 0.15, and z takes the value of 0.12.

[0105] The In x Ga 1-x Thickness of N / GaN superlattice layer: Thickness of highly doped N-type GaN layer: Thickness of multi-quantum-well structure layer: Thickness of undoped Al z Ga 1-z The thickness of layer N is 6:1:2:1.

[0106] The In x Ga 1-x The N / GaN superlattice layer consists of alternating layers of In. x Ga 1-x The N-layer and the second GaN-layer have a period number of 25.

[0107] The multi-quantum-well structure layer includes alternating layers of In y Ga 1-y The N-layer and the first GaN layer have a cycle number of 5.

[0108] The doping concentration of the N-type dopant in the highly doped N-type GaN layer is 1×10⁻⁶. 18 atoms / cm 3 The doping concentration of the N-type dopant in the first GaN layer is 1×10⁻⁶. 17 atoms / cm 3 .

[0109] Comparative Example 1

[0110] This comparative example provides a light-emitting diode epitaxial wafer, which differs from the rest of Example 1 in that its stress relief layer is an alternating stack of GaN and InGaN layers, while the rest is the same as Example 1.

[0111] The light-emitting diode epitaxial wafers prepared in Example 1 and Comparative Example 1 were fabricated into 10mil×24mil chips using the same chip process conditions. 300 LED chips were extracted from each example and tested at a current of 120mA. The luminous efficiency improvement rate of each example was calculated compared with that of the LED prepared in Comparative Example 1. The specific test results are shown in Table 1.

[0112] Table 1. Performance test results of the LEDs prepared in Example 1 and Comparative Example 1

[0113]

[0114] As can be seen from the above results, the LED epitaxial wafer provided by the present invention improves the luminous efficiency of the diode and reduces forward and reverse leakage current.

[0115] In the description of this specification, the references to terms such as "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0116] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A light-emitting diode epitaxial wafer, characterized in that, The substrate includes a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer, and a P-type GaN layer, which are sequentially disposed on the substrate. The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N-layer and the first GaN layer, wherein the value of x ranges from 0.01 to 0.2, the value of y ranges from 0.1 to 0.5, and the value of z ranges from 0.01 to 0.2; The N-type doping concentration of the highly doped N-type GaN layer is higher than that of the multi-quantum-well structure layer; The In x Ga 1-x The growth rate of the N / GaN superlattice layer is greater than that of the multi-quantum-well structure layer, and the In x Ga 1-x The N / GaN superlattice layer is the starting point of the V-shaped pit, and the V-shaped pit extends through the entire multi-quantum-well light-emitting layer. When the highly doped N-type GaN layer grows along the V-shaped sidewall, the thickness near the bottom of the V-shaped pit is greater than that of the V-shaped sidewall, and the potential energy at the bottom of the V-shaped pit is higher than that of the sidewall.

2. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The thickness of the stress relief layer is 100nm~800nm.

3. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The In x Ga 1-x Thickness of N / GaN superlattice layer: Thickness of highly doped N-type GaN layer: Thickness of multi-quantum-well structure layer: Thickness of undoped Al z Ga 1-z The thickness of layer N = (4~6):1:(2~4):

1.

4. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The In x Ga 1-x The N / GaN superlattice layer consists of alternating layers of In. x Ga 1-x The N-layer and the second GaN-layer have a period number of 10 to 50.

5. The light-emitting diode epitaxial wafer as described in claim 4, characterized in that, The In x Ga 1-x The thickness difference between the N layer and the second GaN layer does not exceed 5 nm.

6. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The multi-quantum-well structure layer includes alternating layers of In y Ga 1-y The N-layer and the first GaN layer have a period number of 2 to 10.

7. The light-emitting diode epitaxial wafer as described in claim 6, characterized in that, The first GaN layer is an N-type doped GaN layer, and the doping concentration of its N-type dopant is 1×10⁻⁶. 17 atoms / cm 3 ~1×10 18 atoms / cm 3 ; The In y Ga 1-y The thickness of the N layer is equal to the thickness of the first GaN layer, which is 1:(3~6).

8. The light-emitting diode epitaxial wafer as described in claim 1, characterized in that, The doping concentration of the N-type dopant in the highly doped N-type GaN layer is 1×10⁻⁶. 18 atoms / cm 3 ~1×10 19 atoms / cm 3 .

9. A method for fabricating a light-emitting diode epitaxial wafer as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1, Provide a substrate; S2. Sequentially deposit a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer, and a P-type GaN layer on the substrate. The stress relief layer comprises sequentially stacked In x Ga 1-x N / GaN superlattice layer, highly doped N-type GaN layer, multi-quantum-well structure layer and undoped Al z Ga 1-z N layers, the multi-quantum-well structure layer comprising alternating stacked In y Ga 1-y The N layer and the first GaN layer, wherein the value of x ranges from 0.01 to 0.2, the value of y ranges from 0.1 to 0.5, and the value of z ranges from 0.01 to 0.

2.

10. An LED, characterized in that, The LED includes a light-emitting diode epitaxial wafer as described in any one of claims 1 to 8, or a light-emitting diode epitaxial wafer prepared by the method for preparing a light-emitting diode epitaxial wafer as described in claim 9.

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