Full-spectrum LED epitaxial wafer, preparation method thereof and LED chip

Abstract

The invention relates to the technical field of photoelectricity, and discloses a full-spectrum LED epitaxial wafer, a preparation method thereof and an LED chip, the epitaxial wafer comprises a substrate, and the substrate is sequentially provided with a buffer layer, an N-type GaN layer, a multispectral light-emitting well layer and a P-type GaN layer; the multispectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer which are stacked in sequence, the first light-emitting well layer comprises a plurality of groups of InxGa (1-x) N quantum well layers, AlaGa (1-a) N interface layers and first GaN quantum barrier layers which are stacked in sequence, the second light-emitting well layer comprises a plurality of groups of InyGa (1-y) N quantum well layers, AlbGa (1-b) N interface layers and second GaN quantum barrier layers which are stacked in sequence, and the third light-emitting well layer comprises a plurality of groups of InzGa (1-z) N quantum well layers, AlcGa (1-c) N interface layers and third GaN quantum barrier layers which are stacked in sequence. According to the full-spectrum LED epitaxial wafer provided by the invention, the luminous efficiency and the color rendering index of a full-spectrum chip can be improved.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technology, and in particular to a full-spectrum LED epitaxial wafer and a preparation method thereof, and an LED chip. Background Art

[0002] Full-spectrum LEDs can cover a wider spectrum, including red, orange, yellow, green, blue and other color bands, enabling them to simulate the lighting effects of sunlight and provide a more natural and uniform lighting experience. The most common full-spectrum LEDs are composed of a combination of LED cores with multiple different wavelengths, and their production steps are complex and costly. Another method is to use fluorescent conversion materials, such as fluorescent phosphors or fluorescent dyes, to convert a single wavelength of light into other wavelengths of light to form full-spectrum light, but this method has poor conversion efficiency. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a full-spectrum LED epitaxial wafer, which improves the luminous efficiency and color rendering index of the full-spectrum chip.

[0004] The technical problem to be solved by the present invention is also to provide a method for preparing a full-spectrum LED epitaxial wafer, which has a simple process and can stably prepare a full-spectrum LED epitaxial wafer with good luminous performance.

[0005] In order to solve the above technical problems, the present invention provides a full-spectrum LED epitaxial wafer, comprising a substrate, on which a buffer layer, an N-type GaN layer, a multi-spectrum light-emitting well layer, and a P-type GaN layer are sequentially arranged;

[0006] The multi-spectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, wherein the first light-emitting well layer comprises several groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes several groups of sequentially stacked In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes several groups of sequentially stacked In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and a third GaN quantum barrier layer, the light emission wavelength of the first light emitting well layer is greater than the light emission wavelength of the second light emitting well layer and is greater than the light emission wavelength of the third light emitting well layer.

[0007] In some embodiments, x>y>z.

[0008] In some embodiments, 0.25≤x≤0.35, 0.15≤y≤0.25, and 0.05≤z≤0.15.

[0009] In some embodiments, a>b>c.

[0010] In some embodiments, 0.15≤a≤0.25, 0.1≤b≤0.2, and 0.05≤c≤0.15.

[0011] In some embodiments, the first light emitting well layer includes a L1 group of sequentially stacked In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and the first GaN quantum barrier layer, the second light emitting well layer includes L2 groups of In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes L3 group of In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and the third GaN quantum barrier layer, L3>L2>L1.

[0012] In some embodiments, the emission wavelength of the first light-emitting well layer is in the range of 462 nm to 480 nm;

[0013] The light emission wavelength range of the second light emitting well layer is 445nm to 461nm;

[0014] The light emitting wavelength of the third light emitting well layer is in the range of 428 nm to 444 nm.

[0015] In some embodiments, the thickness of the first GaN quantum barrier layer is greater than the thickness of the second GaN quantum barrier layer and greater than the thickness of the third GaN quantum barrier layer.

[0016] To solve the above problems, the present invention also provides a method for preparing a full-spectrum LED epitaxial wafer, comprising the following steps:

[0017] S1. providing a substrate;

[0018] S2, depositing a buffer layer, an N-type GaN layer, a multi-spectral light-emitting well layer, and a P-type GaN layer on the substrate in sequence;

[0019] The multi-spectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, wherein the first light-emitting well layer comprises several groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes several groups of sequentially stacked In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes several groups of sequentially stacked In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and a third GaN quantum barrier layer, the light emission wavelength of the first light emitting well layer is greater than the light emission wavelength of the second light emitting well layer and is greater than the light emission wavelength of the third light emitting well layer.

[0020] Correspondingly, the present invention further provides an LED chip, wherein the LED chip comprises the full-spectrum LED epitaxial wafer as described above.

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

[0022] In the full-spectrum LED epitaxial wafer provided by the present invention, the multi-spectrum light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, and the first light-emitting well layer comprises a plurality of groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes several groups of sequentially stacked In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes several groups of sequentially stacked In z Ga (1-z) N quantum well layer, Al c Ga (1-c)N interface layer and the third GaN quantum barrier layer, the emission wavelength of the first light-emitting well layer is greater than the emission wavelength of the second light-emitting well layer and greater than the emission wavelength of the third light-emitting well layer. The emission wavelength of the light-emitting well layer close to the N-type GaN layer is longer, and the emission wavelength of the light-emitting well layer close to the P-type GaN layer is shorter. The ground state energy level gradually changes from low to high from the long-wave light-emitting well to the short-wave light-emitting well, and the carriers will preferentially fill the low ground state energy level interval close to the N side, fully improving the distribution uniformity of the carriers from the N side to the P side light-emitting well, while improving the effective radiation recombination efficiency of the long-wave band, making the peak intensity of the three-band spectrum closer, improving the excitation efficiency of the mixed phosphor, and thus improving the color rendering index of the full-spectrum chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of a full-spectrum LED epitaxial wafer provided by the present invention;

[0024] Figure 2 A schematic diagram of the structure of the first light-emitting well layer of the full-spectrum LED epitaxial wafer provided by the present invention;

[0025] Figure 3 A schematic diagram of the structure of the second light-emitting well layer of the full-spectrum LED epitaxial wafer provided by the present invention;

[0026] Figure 4 This is a schematic structural diagram of the third light-emitting well layer of the full-spectrum LED 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 full-spectrum LED epitaxial wafer, such as Figure 1 As shown, it includes a substrate 100, on which a buffer layer 200, an N-type GaN layer 300, a multi-spectral light-emitting well layer 400, and a P-type GaN layer 500 are sequentially arranged;

[0035] The multi-spectral light-emitting well layer 400 includes a first light-emitting well layer 410, a second light-emitting well layer 420 and a third light-emitting well layer 430 stacked in sequence. The first light-emitting well layer 410 includes several groups of In x Ga (1-x) N quantum well layer 411, Al a Ga (1-a) N interface layer 412 and the first GaN quantum barrier layer 413, the second light emitting well layer 420 includes several groups of sequentially stacked In y Ga (1-y) N quantum well layer 421, Al b Ga (1-b) N interface layer 422 and second GaN quantum barrier layer 423, the third light emitting well layer 430 includes several groups of sequentially stacked In z Ga (1-z) N quantum well layer 431, Al c Ga (1-c) N interface layer 432 and third GaN quantum barrier layer 433 , the light emission wavelength of the first light emitting well layer 410 is greater than the light emission wavelength of the second light emitting well layer 420 and is greater than the light emission wavelength of the third light emitting well layer 430 .

[0036] In the full-spectrum LED epitaxial wafer provided by the present invention, the luminescent wavelength of the luminescent well layer close to the N-type GaN layer is longer, and the luminescent wavelength of the luminescent well layer close to the P-type GaN layer is shorter. The ground state energy level gradually changes from low to high from the long-wave luminescent well to the short-wave luminescent well, and the carriers will preferentially fill the low ground state energy level interval close to the N side, fully improving the distribution uniformity of the carriers from the N side to the P side luminescent well, while improving the effective radiation recombination efficiency of the long-wave band, making the peak intensity of the three-band spectrum closer, improving the excitation efficiency of the mixed phosphor, and thus improving the color rendering index of the full-spectrum chip.

[0037] like Figure 2 to Figure 4 As shown, the multi-spectrum light emitting well layer 400 will be described in detail below.

[0038] In some embodiments, the emission wavelength range of the first light-emitting well layer 410 is 462nm to 480nm; the emission wavelength range of the second light-emitting well layer 420 is 445nm to 461nm; the emission wavelength range of the third light-emitting well layer 430 is 428nm to 444nm. Preferably, the emission wavelength range of the first light-emitting well layer 410 is 465nm to 480nm; the emission wavelength range of the second light-emitting well layer 420 is 450nm to 460nm; the emission wavelength range of the third light-emitting well layer 430 is 430nm to 440nm. In some embodiments, by controlling the wavelength range and peak wavelength interval of the light-emitting well layer, the ability to excite the phosphor can be improved, so that the spectrum coverage after final packaging is wider and closer to the full spectrum of sunlight.

[0039] In some embodiments, the first light emitting well layer 410 includes a group L1 of In x Ga (1-x) N quantum well layer 411, Al a Ga (1-a) N interface layer 412 and first GaN quantum barrier layer 413, the second light emitting well layer 420 includes L2 group of sequentially stacked In y Ga (1-y) N quantum well layer 421, Al b Ga (1-b) The N interface layer 422 and the second GaN quantum barrier layer 423, the third light emitting well layer 430 includes L3 groups of In z Ga (1-z) N quantum well layer 431, Al c Ga (1-c) N interface layer 432 and third GaN quantum barrier layer 433, L3>L2>L1. Preferably, 10>L3>L2>L1>1. By controlling the values ​​of L3, L2, and L1, the peak intensities of the three bands are adjusted, the proportion of short-wave blue light peak is improved, and the blue light spectrum intensity in the packaged spectrum is reduced, effectively reducing the blue light damage.

[0040] In some embodiments, x>y>z. Preferably, 0.25≤x≤0.35, 0.15≤y≤0.25, 0.05≤z≤0.15. More preferably, 0.26≤x≤0.35, 0.15≤y≤0.25, 0.05≤z≤0.14. The In composition of the quantum well layers of the three groups of light-emitting well layers along the growth direction gradually changes from large to small. By regulating the In composition, the distribution of the central wavelengths of the three groups of light-emitting well layers is controlled.

[0041] In some embodiments, a>b>c. Preferably, 0.15≤a≤0.25, 0.1≤b≤0.2, 0.05≤c≤0.15. More preferably, 0.15≤a≤0.25, 0.1≤b≤0.14, 0.05≤c≤0.09. The present invention inserts an interface treatment layer AlGaN layer between the quantum well and the quantum barrier, wherein Al atoms can fill the deep energy level defects caused by the excessive In component, thereby improving the product yield.

[0042] In some embodiments, the thickness of the first GaN quantum barrier layer 413 is greater than the thickness of the second GaN quantum barrier layer 423 and greater than the thickness of the third GaN quantum barrier layer 433. The thickness of the GaN quantum barrier layers of the three groups of light-emitting well layers gradually changes from high to low along the growth direction. By regulating the thickness of the barrier, a thick barrier is grown in the quantum well region with a larger In component, which can improve the problem of poor crystal quality caused by In segregation and improve product yield.

[0043] Accordingly, the present invention provides a method for preparing a full-spectrum LED epitaxial wafer, comprising the following steps:

[0044] S1, providing a substrate 100;

[0045] 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.

[0046] S2, sequentially depositing a buffer layer 200, an N-type GaN layer 300, a multi-spectral light-emitting well layer 400, and a P-type GaN layer 500 on the substrate 100;

[0047] The multi-spectral light-emitting well layer 400 includes a first light-emitting well layer 410, a second light-emitting well layer 420 and a third light-emitting well layer 430 stacked in sequence. The first light-emitting well layer 410 includes several groups of In x Ga (1-x) N quantum well layer 411, Al a Ga (1-a) N interface layer 412 and the first GaN quantum barrier layer 413, the second light emitting well layer 420 includes several groups of sequentially stacked In y Ga (1-y) N quantum well layer 421, Al b Ga (1-b) N interface layer 422 and second GaN quantum barrier layer 423, the third light emitting well layer 430 includes several groups of sequentially stacked In z Ga(1-z) N quantum well layer 431, Al c Ga (1-c) N interface layer 432 and third GaN quantum barrier layer 433 , the light emission wavelength of the first light emitting well layer 410 is greater than the light emission wavelength of the second light emitting well layer 420 and is greater than the light emission wavelength of the third light emitting well layer 430 .

[0048] Specifically, the above step S2 specifically includes the following steps:

[0049] S21 , depositing the buffer layer 200 on the substrate 100 .

[0050] In some embodiments, an AlN buffer layer is deposited in an applied material PVD process. The AlN buffer layer provides nucleation centers with the same orientation as the substrate, releases the stress caused by the lattice mismatch between GaN and the substrate and the thermal stress caused by the mismatch in thermal expansion coefficients, provides a flat nucleation surface for further growth, reduces the contact angle of nucleation growth, and enables the island-like grown GaN grains to be connected into a surface within a smaller thickness, thus transforming into two-dimensional epitaxial growth.

[0051] S22 , depositing the N-type GaN layer 300 on the buffer layer 200 .

[0052] 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.

[0053] S23 , depositing the multi-spectrum light-emitting well layer 400 on the N-type GaN layer 300 .

[0054] In some embodiments, the multi-spectral light-emitting well layer is prepared by the following method:

[0055] The first light emitting well layer 410 , the second light emitting well layer 420 and the third light emitting well layer 430 are grown in sequence to obtain a multi-spectrum light emitting well layer.

[0056] In some embodiments, the first light-emitting well layer 410 is manufactured by the following method:

[0057] Keep the growth temperature of the reaction chamber at 820℃~935℃ and the growth pressure at 50torr~390torr, and grow several groups of In layers stacked in sequence. x Ga (1-x) N quantum well layer 411, Al a Ga (1-a) The N interface layer 412 and the first GaN quantum barrier layer 413 form a first light emitting well layer 410;

[0058] The second light-emitting well layer 420 is prepared by the following method:

[0059] Keep the growth temperature of the reaction chamber at 820℃~935℃ and the growth pressure at 50torr~390torr, and grow several groups of In layers stacked in sequence. y Ga (1-y) N quantum well layer 421, Al b Ga (1-b) The N interface layer 422 and the second GaN quantum barrier layer 423 are used to obtain the second light emitting well layer 420;

[0060] The third light-well layer 430 is manufactured by the following method:

[0061] Keep the growth temperature of the reaction chamber at 820℃~935℃ and the growth pressure at 50torr~390torr, and grow several groups of In layers stacked in sequence. z Ga (1-z) N quantum well layer 431, Al c Ga (1-c) The N interface layer 432 and the third GaN quantum barrier layer 433 form a third light emitting well layer 430 .

[0062] S24 , depositing the P-type GaN layer 500 on the multi-spectrum light-emitting well layer 400 .

[0063] 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.

[0064] Correspondingly, the present invention also provides an LED chip, which includes the above-mentioned full-spectrum LED epitaxial wafer. The full-spectrum LED epitaxial wafer is the basic material for the manufacture of LED chips, and the quality and characteristics of the full-spectrum LED epitaxial wafer directly affect the performance and output of the final LED chip. In some embodiments, the LED chip is made by the following method, and the full-spectrum LED epitaxial wafer is made into a core particle, encapsulated in a bracket, and coated with a mixed phosphor. Preferably, the full-spectrum LED epitaxial wafer is made into a 2235 model core particle, encapsulated in a 3528 bracket, and then coated with a mixed phosphor composed of three color phosphors of blue, green and red. The present invention utilizes the multi-spectrum design of the light-emitting well in the epitaxial structure layer to improve the luminous efficiency and color rendering index of the full-spectrum chip, improve the continuity of the full-spectrum spectrum, and effectively reduce the damage of blue light.

[0065] The present invention is further described below with specific embodiments:

[0066] Example 1

[0067] This embodiment provides a full-spectrum LED epitaxial wafer, including a substrate, on which a buffer layer, an N-type GaN layer, a multi-spectrum light-emitting well layer, and a P-type GaN layer are sequentially provided;

[0068] The multi-spectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, wherein the first light-emitting well layer comprises two groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes three groups of sequentially stacked In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes 5 groups of In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and a third GaN quantum barrier layer, the light emission wavelength of the first light emitting well layer is greater than the light emission wavelength of the second light emitting well layer and is greater than the light emission wavelength of the third light emitting well layer.

[0069] Among them, x is 0.3, y is 0.25, z is 0.1, a is 0.15, b is 0.1, and c is 0.05.

[0070] Example 2

[0071] This embodiment provides a full-spectrum LED epitaxial wafer, including a substrate, on which a buffer layer, an N-type GaN layer, a multi-spectrum light-emitting well layer, and a P-type GaN layer are sequentially provided;

[0072] The multi-spectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, wherein the first light-emitting well layer comprises two groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes three groups of sequentially stacked In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes 5 groups of In z Ga (1-z) N quantum well layer, Al c Ga (1-c)N interface layer and a third GaN quantum barrier layer, the light emission wavelength of the first light emitting well layer is greater than the light emission wavelength of the second light emitting well layer and is greater than the light emission wavelength of the third light emitting well layer.

[0073] Among them, x is 0.3, y is 0.25, z is 0.1, a is 0.25, b is 0.2, and c is 0.15.

[0074] Example 3

[0075] This embodiment provides a full-spectrum LED epitaxial wafer, including a substrate, on which a buffer layer, an N-type GaN layer, a multi-spectrum light-emitting well layer, and a P-type GaN layer are sequentially provided;

[0076] The multi-spectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, wherein the first light-emitting well layer comprises two groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes three groups of sequentially stacked In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes 5 groups of In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and a third GaN quantum barrier layer, the light emission wavelength of the first light emitting well layer is greater than the light emission wavelength of the second light emitting well layer and is greater than the light emission wavelength of the third light emitting well layer.

[0077] Among them, x is 0.25, y is 0.2, z is 0.15, a is 0.15, b is 0.1, and c is 0.05.

[0078] Example 4

[0079] This embodiment provides a full-spectrum LED epitaxial wafer, including a substrate, on which a buffer layer, an N-type GaN layer, a multi-spectrum light-emitting well layer, and a P-type GaN layer are sequentially provided;

[0080] The multi-spectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, wherein the first light-emitting well layer comprises two groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes 4 groups of sequentially stacked Iny Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes 5 groups of In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and a third GaN quantum barrier layer, the light emission wavelength of the first light emitting well layer is greater than the light emission wavelength of the second light emitting well layer and is greater than the light emission wavelength of the third light emitting well layer.

[0081] Among them, x is 0.3, y is 0.25, z is 0.1, a is 0.15, b is 0.1, and c is 0.05.

[0082] Comparative Example 1

[0083] The present comparative example provides a full-spectrum LED epitaxial wafer, including a substrate, on which a buffer layer, an N-type GaN layer, a light-emitting well layer, and a P-type GaN layer are sequentially provided; the light-emitting well layer includes In x Ga (1-x) N quantum well layer and GaN quantum barrier layer, wherein x is 0.3.

[0084] The full-spectrum LED epitaxial wafers prepared in Examples 1 to 4 and Comparative Example 1 were used to prepare LED chips using the same chip process conditions, specifically including: making a 2235 model core particle, encapsulating it in a 3528 bracket, and then coating it with a mixed phosphor composed of three color phosphors of blue, green, and red. Electrical tests were performed under a 2235 chip process @120mA test current, and the specific test results are shown in Table 1.

[0085] Table 1 Performance test results of LED chips prepared in Examples 1 to 4 and Comparative Example 1

[0086]

[0087] The luminous efficiency of the package made of the epitaxial wafer proposed by the present invention is improved by about 2%, the color rendering index is improved by about 1% to 2%, and the product yield is also improved. The present invention has a longer luminous wavelength in the luminescent well layer close to the N-type GaN layer, and a shorter luminescent wavelength in the luminescent well layer close to the P-type GaN layer. The ground state energy level gradually changes from low to high from the long-wave luminescent well to the short-wave luminescent well, and the carriers will preferentially fill the low ground state energy level interval close to the N side, fully improving the distribution uniformity of the carriers from the N side to the P side luminescent well, while improving the effective radiation recombination efficiency of the long-wave band, making the peak intensity of the three-band spectrum closer, improving the excitation efficiency of the mixed phosphor, and then improving the color rendering index of the full-spectrum chip.

[0088] 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.

[0089] 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 full-spectrum LED epitaxial wafer, characterized in that: It comprises a substrate, on which a buffer layer, an N-type GaN layer, a multi-spectral light-emitting well layer, and a P-type GaN layer are sequentially arranged; The multi-spectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, wherein the first light-emitting well layer comprises several groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes several groups of sequentially stacked In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes several groups of sequentially stacked In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and a third GaN quantum barrier layer, the light emission wavelength of the first light emitting well layer is greater than the light emission wavelength of the second light emitting well layer and is greater than the light emission wavelength of the third light emitting well layer.

2. The full-spectrum LED epitaxial wafer according to claim 1, characterized in that: x>y>z.

3. The full-spectrum LED epitaxial wafer according to claim 1, characterized in that: 0.25≤x≤0.35, 0.15≤y≤0.25, 0.05≤z≤0.

15.

4. The full-spectrum LED epitaxial wafer according to claim 1, characterized in that: a>b>c.

5. The full-spectrum LED epitaxial wafer according to claim 1, characterized in that: 0.15≤a≤0.25, 0.1≤b≤0.2, 0.05≤c≤0.

15.

6. The full-spectrum LED epitaxial wafer according to claim 1, characterized in that: The first light-emitting well layer includes a group L1 of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and the first GaN quantum barrier layer, the second light emitting well layer includes L2 groups of In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes L3 group of In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and the third GaN quantum barrier layer, L3>L2>L1.

7. The full-spectrum LED epitaxial wafer according to claim 1, characterized in that: The light emission wavelength range of the first light emitting well layer is 462nm to 480nm; The light emission wavelength range of the second light emitting well layer is 445nm to 461nm; The light emitting wavelength of the third light emitting well layer is in the range of 428 nm to 444 nm.

8. The full-spectrum LED epitaxial wafer according to claim 1, characterized in that: The thickness of the first GaN quantum barrier layer is greater than the thickness of the second GaN quantum barrier layer and greater than the thickness of the third GaN quantum barrier layer.

9. A method for preparing a full-spectrum LED epitaxial wafer as claimed in 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 N-type GaN layer, a multi-spectral light-emitting well layer, and a P-type GaN layer on the substrate in sequence; The multi-spectral light-emitting well layer comprises a first light-emitting well layer, a second light-emitting well layer and a third light-emitting well layer stacked in sequence, wherein the first light-emitting well layer comprises several groups of In x Ga (1-x) N quantum well layer, Al a Ga (1-a) N interface layer and a first GaN quantum barrier layer, the second light emitting well layer includes several groups of sequentially stacked In y Ga (1-y) N quantum well layer, Al b Ga (1-b) N interface layer and the second GaN quantum barrier layer, the third light emitting well layer includes several groups of sequentially stacked In z Ga (1-z) N quantum well layer, Al c Ga (1-c) N interface layer and a third GaN quantum barrier layer, the light emission wavelength of the first light emitting well layer is greater than the light emission wavelength of the second light emitting well layer and is greater than the light emission wavelength of the third light emitting well layer.

10. An LED chip, characterized in that: The LED chip comprises the full-spectrum LED epitaxial wafer as claimed in any one of claims 1 to 8.

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