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

Abstract

The invention relates to the technical field of photoelectricity, and discloses a light-emitting diode epitaxial wafer and a preparation method thereof, and an LED, the light-emitting diode epitaxial wafer comprises a substrate, and the substrate is sequentially provided with a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer; the stress release layer comprises an In < x > Ga < 1-x > N / GaN superlattice layer, a highly-doped N-type GaN layer, a multi-quantum well structure layer and an undoped Al < z > Ga < 1-z > N layer which are stacked in sequence, the multi-quantum well structure layer comprises In < y > Ga < 1-y > N layers and first GaN layers which are stacked alternately, the value range of x is 0.01-0.2, the value range of y is 0.1-0.5, and the value range of z is 0.01-0.2. The light-emitting diode epitaxial wafer provided by the invention improves the light-emitting efficiency of the diode and reduces the forward and reverse electric leakage phenomenon.

Description

Technical Field

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

[0002] With the improvement of various aspects of the performance of light-emitting diodes, light-emitting diodes have gradually replaced incandescent lamps as a new generation of lighting products, and are widely used in intelligent lighting, architectural lighting, communications, security and other aspects. GaN-based light-emitting diodes with multi-quantum well structure as the main light-emitting layer have a high radiative recombination efficiency and have become the core technology in the semiconductor field in recent years. Its growth method is mainly based on the alternating growth of two materials with different bandgap widths, InGaN / GaN. The bandgap width of InGaN is smaller than that of GaN. During the transmission process of electrons from N-type semiconductors to P-type semiconductors, it is easier to be confined to the quantum well layer with a small bandgap width to radiate and recombine with holes. Therefore, the InGaN / GaN multi-quantum well structure plays a role in limiting carriers and improving the radiative recombination efficiency. However, due to the poor matching of the lattice constants of InGaN and GaN, a large strain polarization electric field is generated, resulting in severe energy band tilting, and the overflow phenomenon seriously exacerbates the light efficiency attenuation.

[0003] In order to reduce the piezoelectric polarization effect caused by lattice mismatch and effectively release the stress in the quantum well region, a low-In component InGaN / GaN quantum well preparation layer or InGaN / GaN superlattice preparation layer is usually grown before the quantum well layer. The simple InGaN / GaN quantum well preparation layer or InGaN / GaN superlattice preparation layer is affected by the extension of the underlying defects or the mismatch of the growth temperature, resulting in serious In segregation and poor crystal quality; at the same time, the uneven stress release layer deteriorates the crystal quality of the subsequently grown quantum well layer, and the defects penetrate into the multi-quantum well layer, increasing the probability of non-radiative recombination in the multi-quantum well layer, 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 a light emitting diode epitaxial wafer, which improves the light emitting efficiency of the diode and reduces the forward and reverse leakage phenomenon.

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a light emitting diode epitaxial wafer, which has a simple process and can stably prepare a light emitting diode epitaxial wafer with good luminous efficiency.

[0006] In order to solve the above technical problems, the present invention provides a light-emitting diode epitaxial wafer, comprising a substrate, on which a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially arranged;

[0007] The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and a first GaN layer, wherein the value range of x is 0.01 to 0.2, the value range of y is 0.1 to 0.5, and the value range of z is 0.01 to 0.2.

[0008] In some embodiments, the stress release layer has a thickness of 100 nm to 800 nm.

[0009] In some embodiments, 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: Undoped Al z Ga 1-z The thickness of the N layer = (4~6):1:(2~4):1.

[0010] In some embodiments, the In x Ga 1-x The N / GaN superlattice layer consists of alternately stacked In x Ga 1-x The number of periods of the N layer and the second GaN layer is 10 to 50.

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

[0012] In some embodiments, the multi-quantum well structure layer includes alternately stacked 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 17 atoms / cm 3 ~1×10 18 atoms / cm 3 ;

[0014] In y Ga 1-y The thickness of the N layer: the 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 18 atoms / cm 3 ~1×10 19 atoms / cm 3 .

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

[0017] S1. providing a substrate;

[0018] S2, depositing a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer on the substrate in sequence;

[0019] The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and a first GaN layer, wherein the value range of x is 0.01 to 0.2, the value range of y is 0.1 to 0.5, and the value range of z is 0.01 to 0.2.

[0020] Correspondingly, the present invention further provides an LED, which includes the light-emitting diode epitaxial wafer as described above, or includes the light-emitting diode epitaxial wafer manufactured by the method for manufacturing the light-emitting diode epitaxial wafer as described above.

[0021] The implementation of the present invention has the following beneficial effects:

[0022] In the light-emitting diode epitaxial wafer provided by the present invention, the stress release layer includes a superlattice structure and a multi-quantum well structure, which can effectively avoid the problem of poor quality of the bottom layer defect extension crystal, or the problem of serious In segregation caused by factors such as growth temperature mismatch. Specifically, In x Ga 1-x The N / GaN superlattice layer has a lower In component content, so its crystal quality is better than that of the multi-quantum well layer, and it effectively suppresses the In segregation phenomenon of the subsequent multi-quantum well layer, providing a growth substrate with better crystal quality for the multi-quantum well layer. The multi-quantum well structure layer includes alternately stacked In y Ga 1-yOn the one hand, the N layer and the first GaN layer can provide favorable conditions for opening V-type defects in the epitaxial structure, thereby increasing the efficiency of hole injection from the side walls of the V-type 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 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 is used 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, so that its built-in electric field strength fully offsets the QCSE effect caused by piezoelectric polarization and effectively eliminates the 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 side wall, the thickness near the bottom of the V-shaped pit is thicker than the V-shaped side wall. The potential energy at the bottom of the V-shaped pit is higher than the potential energy of the side wall. Holes are more easily injected into the light-emitting well area from the V-shaped opening close to the P side, thereby improving the light-emitting efficiency.

[0025] Furthermore, undoped Al z Ga 1-z In the N layer, Al atoms have a small lattice constant and low mobility, which can fully fill the deep energy level defects caused by lattice mismatch in the multi-quantum well light-emitting layer, reduce the forward leakage rate, and increase the turn-on voltage. z Ga 1-z The N layer can effectively prevent the N-side electrons from overshooting into the multi-quantum well light-emitting layer, resulting in uneven distribution of carriers and Auger recombination. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of the light emitting diode epitaxial wafer provided by the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0032] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0033] In the present invention, "preferred" and "better" are only used to describe implementation methods or embodiments with better effects, and it should be understood that they do not constitute a limitation on the scope of protection of the present invention. In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features. In the present invention, when involving numerical ranges, unless otherwise specified, the two endpoints of the numerical range are included.

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

[0035] The stress release layer 500 includes In x Ga 1-x N / GaN superlattice layer 510, highly doped N-type GaN layer 520, multi-quantum well structure layer 530 and undoped Al z Ga 1-z N layer 540, the multi-quantum well structure layer 530 includes alternately stacked In y Ga 1-y N layer and a first GaN layer, wherein the value range of x is 0.01 to 0.2, the value range of y is 0.1 to 0.5, and the value range of z is 0.01 to 0.2.

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

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

[0038] In some embodiments, the In x Ga 1-x The N / GaN superlattice layer 510 includes In x Ga 1-x The number of periods of the N layer and the second GaN layer is 10 to 50; exemplary numbers of periods are 15, 20, 25, 30, 35, 40, 45, but are not limited to the above. x Ga 1-x The thickness difference between the N layer and the second GaN layer does not exceed 5nm. x Ga 1-x The N / GaN superlattice layer has a lower In component content, so its crystal quality is better than that of the multi-quantum well layer, and it effectively suppresses the In segregation phenomenon of 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 18 atoms / cm 3 ~1×10 19 atoms / cm 3The exemplary N-type dopant doping concentration of the highly doped N-type GaN layer 520 is 2×10 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 , but not limited to the above. 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 the N-type doping concentration of the subsequent multi-quantum well structure layer 530, so that its built-in electric field strength fully offsets the QCSE effect caused by piezoelectric polarization and effectively eliminates 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. In addition, when the highly doped N-type GaN layer 520 grows along the V-shaped sidewall, the thickness near the bottom of the V-shaped pit is thicker than the V-shaped sidewall. The potential energy at the bottom of the V-shaped pit is higher than the potential energy of the sidewall, and holes are more easily injected into the light-emitting well area from the V-shaped opening near the P side, thereby improving the light-emitting efficiency.

[0040] In some embodiments, the multi-quantum well structure layer 530 includes alternately stacked 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.

[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 17 atoms / cm 3 ~1×10 18 atoms / cm 3 The exemplary doping concentration of the N-type dopant of the first GaN layer is 2×10 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 , but not limited to the above. The N-type doping concentration of the first GaN layer is lower than the N-type doping concentration of the highly doped N-type GaN layer 520, so that its built-in electric field strength can fully offset 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.

[0042] In some embodiments, the In y Ga 1-y The thickness of the N layer: the thickness of the first GaN layer = 1: (3-6). 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. The multi-quantum well structure layer 530 includes alternately stacked In y Ga 1-y On the one hand, the N layer and the first GaN layer can provide favorable conditions for opening V-type defects in the epitaxial structure, thereby increasing the efficiency of hole injection from the side walls of the V-type 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, an undoped Al layer is inserted behind the multi-quantum well structure layer 530. z Ga 1-z The N layer 540 acts as a defect shielding layer. z Ga 1-z In the N layer, Al atoms have a small lattice constant and low mobility, which can fully fill the deep energy level defects caused by lattice mismatch in the multi-quantum well light-emitting layer, reduce the forward leakage rate, and increase the turn-on voltage. z Ga 1-zThe N layer can effectively prevent the N-side electrons from overshooting into the multi-quantum well light-emitting layer, resulting in uneven distribution of carriers and Auger recombination.

[0044] In summary, in the light-emitting diode epitaxial wafer provided by the present invention, the stress release layer includes a superlattice structure and a multi-quantum well structure, which can effectively avoid the problem of poor quality of the bottom layer defect extension crystal, or the problem of serious In segregation caused by factors such as growth temperature mismatch. 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 is used as a defect shielding layer. The combined effect of the above four sub-layers improves the luminous efficiency of the diode and reduces forward and reverse leakage.

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

[0046] S1, providing a substrate 100;

[0047] In some embodiments, the substrate 100 may be selected from one of a sapphire substrate, a SiO2 sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, and a zinc oxide substrate. Preferably, the substrate 100 is a sapphire substrate, which is a commonly used GaN-based LED substrate material. The sapphire substrate has a mature preparation process, a low price, is easy to clean and handle, and has good stability at high temperatures.

[0048] S2, sequentially depositing a buffer layer 200, a non-doped GaN layer 300, an N-type GaN layer 400, a stress release layer 500, a multi-quantum well light-emitting layer 600, an electron blocking layer 700, and a P-type GaN layer 800 on the substrate 100;

[0049] The stress release layer 500 includes In x Ga 1-x N / GaN superlattice layer 510, highly doped N-type GaN layer 520, multi-quantum well structure layer 530 and undoped Al z Ga 1-z N layer 540, the multi-quantum well structure layer 530 includes alternately stacked In y Ga 1-y N layer and a first GaN layer, wherein the value range of x is 0.01 to 0.2, the value range of y is 0.1 to 0.5, and the value range of z is 0.01 to 0.2.

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

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

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

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

[0054] In some embodiments, the temperature of the reaction chamber is controlled at 1000° C. to 1200° C., the pressure is controlled at 100 torr to 600 torr, N source and Ga source are introduced, and a non-doped GaN layer with a thickness of 1 μm to 5 μm is grown.

[0055] S23 , depositing 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° C. to 1200° C., the pressure is controlled at 100 torr to 600 torr, and an N source, a Ga source, and a Si source are introduced to grow the N-type GaN layer.

[0057] S24 , depositing the stress release 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 the growth rate of the multi-quantum well structure layer 530. This can effectively control the morphology of large V-shaped pits and reduce the number of small V-shaped pits that affect the crystal quality. x Ga 1-x The N / GaN superlattice layer 510 is a fast-growing layer. The fast-growing method makes it easier for dislocations to evolve into V-shaped defects, that is, to become the starting point of the V-shaped pit, so that the V-shaped pit can penetrate the entire light-emitting layer. Larger V-shaped pits can effectively shield dislocations and improve hole injection efficiency. The multi-quantum well structure layer 530 slows down its growth to effectively avoid small defects in the GaN layer of the multi-quantum well structure layer 530, reduce leakage channels, and improve product yield.

[0059] S25 , depositing the multi-quantum well light-emitting layer 600 on the stress release layer 500 .

[0060] In some embodiments, the multi-quantum well light-emitting layer is an alternately stacked InGaN quantum well layer and an AlGaN quantum barrier layer, with a stacking period number 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 50torr to 300torr; 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 50torr to 300torr.

[0061] S26, depositing 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, 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 , depositing 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 further provides an LED, which comprises the above-mentioned light-emitting diode epitaxial wafer, wherein the photoelectric efficiency of the LED is effectively improved and other electrical properties are good.

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

[0067] Example 1

[0068] This embodiment provides a light-emitting diode epitaxial wafer, comprising a substrate, on which a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially provided;

[0069] The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, wherein the value of x is 0.015, the value of y is 0.15, and the value of z is 0.12.

[0070] 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: Undoped Al z Ga 1-z The thickness of N layer = 4:1:4:1.

[0071] In x Ga 1-x The N / GaN superlattice layer consists of alternately stacked In x Ga 1-x The number of periods of the N layer and the second GaN layer is 25.

[0072] The multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, the number of periods is 5.

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

[0074] Example 2

[0075] This embodiment provides a light-emitting diode epitaxial wafer, comprising a substrate, on which a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially provided;

[0076] The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, wherein the value of x is 0.015, the value of y is 0.15, and the value of z is 0.12.

[0077] 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: Undoped Al z Ga 1-zThe thickness of N layer = 4:1:4:1.

[0078] In x Ga 1-x The N / GaN superlattice layer consists of alternately stacked In x Ga 1-x The number of periods of the N layer and the second GaN layer is 25.

[0079] The multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, the number of periods is 6.

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

[0081] Example 3

[0082] This embodiment provides a light-emitting diode epitaxial wafer, comprising a substrate, on which a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially provided;

[0083] The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, wherein the value of x is 0.018, the value of y is 0.18, and the value of z is 0.12.

[0084] 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: Undoped Al z Ga 1-z The thickness of N layer = 4:1:4:1.

[0085] In x Ga 1-x The N / GaN superlattice layer consists of alternately stacked In x Ga 1-x The number of periods of the N layer and the second GaN layer is 25.

[0086] The multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, the number of periods is 5.

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

[0088] Example 4

[0089] This embodiment provides a light-emitting diode epitaxial wafer, comprising a substrate, on which a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially provided;

[0090] The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, wherein the value of x is 0.015, the value of y is 0.15, and the value of z is 0.15.

[0091] 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: Undoped Al z Ga 1-z The thickness of N layer = 4:1:4:1.

[0092] In x Ga 1-x The N / GaN superlattice layer consists of alternately stacked In x Ga 1-x The number of periods of the N layer and the second GaN layer is 25.

[0093] The multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, the number of periods is 5.

[0094] The doping concentration of the N-type dopant in the highly doped N-type GaN layer is 1×1018 atoms / cm 3 The doping concentration of the N-type dopant in the first GaN layer is 1×10 17 atoms / cm 3 .

[0095] Example 5

[0096] This embodiment provides a light-emitting diode epitaxial wafer, comprising a substrate, on which a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially provided;

[0097] The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, wherein the value of x is 0.015, the value of y is 0.15, and the value of z is 0.12.

[0098] 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: Undoped Al z Ga 1-z The thickness of N layer = 4:1:4:1.

[0099] In x Ga 1-x The N / GaN superlattice layer consists of alternately stacked In x Ga 1-x The number of periods of the N layer and the second GaN layer is 25.

[0100] The multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, the number of periods is 5.

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

[0102] Example 6

[0103] This embodiment provides a light-emitting diode epitaxial wafer, comprising a substrate, on which a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially provided;

[0104] The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, wherein the value of x is 0.015, the value of y is 0.15, and the value of z is 0.12.

[0105] 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: Undoped Al z Ga 1-z The thickness of the N layer = 6:1:2:1.

[0106] In x Ga 1-x The N / GaN superlattice layer consists of alternately stacked In x Ga 1-x The number of periods of the N layer and the second GaN layer is 25.

[0107] The multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and the first GaN layer, the number of periods is 5.

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

[0109] Comparative Example 1

[0110] This comparative example provides a light emitting diode epitaxial wafer, which is different from the other embodiment 1 in that its stress release layer is alternately stacked GaN layers and InGaN layers, and the rest is the same as the embodiment 1.

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

[0112] Table 1 Performance test results of LEDs obtained in Example 1 and Comparative Example 1

[0113]

[0114] It can be seen from the above results that the light-emitting diode epitaxial wafer provided by the present invention improves the light-emitting efficiency of the diode and reduces the forward and reverse leakage phenomenon.

[0115] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0116] The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. These improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A light emitting diode epitaxial wafer, characterized in that: It comprises a substrate, on which a buffer layer, a non-doped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer are sequentially arranged; The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and a first GaN layer, wherein the value range of x is 0.01 to 0.2, the value range of y is 0.1 to 0.5, and the value range of z is 0.01 to 0.

2.

2. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The thickness of the stress release layer is 100nm-800nm.

3. The light emitting diode epitaxial wafer according to claim 1, characterized in that: 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: Undoped Al z Ga 1-z The thickness of the N layer = (4~6):1:(2~4):

1.

4. The light emitting diode epitaxial wafer according to claim 1, characterized in that: In x Ga 1-x The N / GaN superlattice layer consists of alternately stacked In x Ga 1-x The number of periods of the N layer and the second GaN layer is 10 to 50.

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

6. The light emitting diode epitaxial wafer according to claim 1, characterized in that: The multi-quantum well structure layer includes alternately stacked 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 according to claim 6, characterized in that: The first GaN layer is an N-type doped GaN layer, and the doping concentration of the N-type dopant is 1×10 17 atoms / cm 3 ~1×10 18 atoms / cm 3 ; In y Ga 1-y The thickness of the N layer: the thickness of the first GaN layer = 1: (3-6).

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

9. A method for preparing a light emitting diode epitaxial wafer according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. providing a substrate; S2, depositing a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type GaN layer on the substrate in sequence; The stress release layer includes 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 layer, the multi-quantum well structure layer includes alternately stacked In y Ga 1-y N layer and a first GaN layer, wherein the value range of x is 0.01 to 0.2, the value range of y is 0.1 to 0.5, and the value range of z is 0.01 to 0.

2.

10. An LED, characterized in that: The LED comprises the light emitting diode epitaxial wafer as claimed in any one of claims 1 to 8 or comprises a light emitting diode epitaxial wafer manufactured by the method for manufacturing a light emitting diode epitaxial wafer as claimed in claim 9.

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