A multi-band LED chip and its preparation method, white light LED light source

Abstract

The present invention relates to the field of semiconductor technology, and specifically discloses a multi-band LED chip and a preparation method thereof, and a white light LED light source. The LED chip includes a light-emitting layer, and the light-emitting layer includes a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer, and a fourth violet multi-quantum well layer stacked in sequence along the epitaxial direction; the first cyan multi-quantum well layer to the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers, and the emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, and the band gap widths of the barrier layers decrease in sequence. The LED chip of the present invention can effectively improve the overall excitation efficiency, and the output full-spectrum white light LED light source has a higher color rendering index, better stability, less damage to the human eye, and high luminous efficiency.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a multi-band LED chip and a preparation method thereof, and a white light LED light source. Background Art

[0002] Currently, the mainstream technology for full-spectrum white LEDs utilizes a blue LED chip to excite a mixed red and green phosphor layer (containing red and green phosphors), thereby achieving full-spectrum white light output. However, the spectral curve of this type of full-spectrum white LED source exhibits significant fluctuations in the blue band and poor stability, impacting both luminous performance and operational safety.

[0003] From the perspective of the luminescence mechanism, the instability of the blue light spectrum makes it difficult to achieve the optimal match between the blue light energy and the absorption and conversion efficiency of the phosphor when exciting the phosphor to produce white light. The phosphor is difficult to be stably and fully excited by the blue light energy, and the emission intensity of the green and red light also fluctuates accordingly, resulting in a decrease in the overall luminous efficiency of the white light LED, affecting the stability of the light output, and causing a decrease in the color rendering index.

[0004] From a health risk perspective, the hazards of blue light should not be ignored. The unstable spectrum of blue light can cause flickering, which is imperceptible to the naked eye. Long-term exposure to this light source can easily cause symptoms such as eye fatigue and dryness, and may even damage vision. As early as 1966, Nell et al. found that blue light exposure (especially shortwave blue light) can easily damage retinal cells. Long-term exposure can lead to serious consequences such as decreased or even complete vision loss. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-band LED chip and a preparation method thereof, and a white light LED light source in response to the existing technical status.

[0006] The LED chip of the present invention can emit light of multiple different wavelengths, such as cyan light, long-wave blue light, short-wave blue light and violet light. The synergistic effect of light of multiple different wavelengths can more fully excite red phosphor and green phosphor, effectively improving the overall excitation efficiency. The output full-spectrum white light LED light source has a higher color rendering index, better stability, less damage to the human eye, and high luminous efficiency.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] First, the present invention provides a multi-band LED chip, comprising a substrate and an epitaxial layer arranged on the substrate, wherein the epitaxial layer comprises a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer arranged in sequence along the epitaxial direction;

[0009] The light-emitting layer comprises a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer stacked in sequence along the epitaxial direction;

[0010] The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers.

[0011] The emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence.

[0012] The bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease in sequence.

[0013] In some embodiments, the emission wavelength of the first cyan multi-quantum well layer is 490nm~500nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 460nm~480nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 445nm~460nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430nm~445nm.

[0014] In some embodiments, each barrier layer includes a front Si-doped GaN layer, an AlGaN layer not intentionally doped with Si, and a back Si-doped GaN layer sequentially stacked along the epitaxial direction.

[0015] Moreover, the Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth purple multi-quantum well layer decreases successively, and the total thickness of the single barrier layer decreases successively.

[0016] In some embodiments, the Al component contents of the AlGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth purple multi-quantum well layer are x1, x2, x3, and x4, respectively, wherein 0.03≤x1≤0.15, 0.02≤x2≤0.12, 0.01≤x3≤0.1, and 0<x4≤0.08.

[0017] In some embodiments, the growth temperatures of the Si-doped front GaN layer and the Si-doped back GaN layer of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer increase successively, the Si doping concentration decreases successively, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer decreases successively, and the single layer thickness of each of the AlGaN layers that are not intentionally doped with Si is the same and the growth temperature is the same.

[0018] In some embodiments, in the first cyan multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 820° C. to 913° C., and the Si doping concentration is 1.5×10 17 / cm 3 ~7.9×10 17 / cm 3 In the second long-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 825°C~918°C, and the Si doping concentration is 1.3×10 17 / cm 3 ~7.3×10 17 / cm 3 In the third short-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 830°C~923°C, and the Si doping concentration is 1.1×10 17 / cm 3 ~6.7×10 17 / cm 3 In the fourth purple multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 835°C~928°C, and the Si doping concentration is 0.9×10 17 / cm 3 ~6.3×10 17 / cm 3 and / or,

[0019] In the first cyan multi-quantum well layer, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 6 nm to 12 nm; in the second long-wave blue multi-quantum well layer, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 5.2 nm to 11.2 nm; in the third short-wave blue multi-quantum well layer, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4.6 nm to 10.6 nm; in the fourth violet multi-quantum well layer, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4 nm to 10 nm; and / or,

[0020] The thickness of each AlGaN layer not intentionally doped with Si is 1 nm to 5 nm, and the growth temperature is 780° C. to 928° C.

[0021] In some embodiments, each of the well layers includes an InGaN layer that is not intentionally doped with Si, and the In component content of the InGaN layer that is not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth purple multi-quantum well layer decreases successively, and the growth temperature increases successively.

[0022] Secondly, the present invention provides a method for preparing a multi-band LED chip, comprising:

[0023] providing a substrate;

[0024] Depositing an epitaxial layer on the substrate, wherein the epitaxial layer includes a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer sequentially arranged along an epitaxial direction;

[0025] The light-emitting layer comprises a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer stacked in sequence along the epitaxial direction;

[0026] The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers.

[0027] The emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence.

[0028] The bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease in sequence.

[0029] In some embodiments, the first cyan multi-quantum well layer has an emission wavelength of 490 nm to 500 nm, the second long-wave blue multi-quantum well layer has an emission wavelength of 460 nm to 480 nm, the third short-wave blue multi-quantum well layer has an emission wavelength of 445 nm to 460 nm, and the fourth violet multi-quantum well layer has an emission wavelength of 430 nm to 445 nm; and / or,

[0030] Each of the barrier layers includes a front Si-doped GaN layer, an AlGaN layer not intentionally doped with Si, and a back Si-doped GaN layer stacked sequentially along the epitaxial direction, and the Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases sequentially, and the total thickness of a single barrier layer decreases sequentially.

[0031] Furthermore, the present invention provides a white light LED light source, comprising a fluorescent adhesive layer and the above-mentioned LED chip, wherein the fluorescent adhesive layer comprises red fluorescent powder and green fluorescent powder.

[0032] The beneficial effects of the present invention are:

[0033] First, compared with the existing technical solution of using a single blue light as the excitation light source for the red and green mixed phosphor layer, the LED chip of the present invention can simultaneously emit excitation light of multiple different bands to cooperate with the red and green mixed phosphor layer to achieve full-spectrum white light. Specifically, the light-emitting layer of the present invention includes a first cyan light multi-quantum well layer, a second long-wave blue light multi-quantum well layer, a third short-wave blue light multi-quantum well layer and a fourth violet light multi-quantum well layer stacked in sequence along the epitaxial direction, and the light-emitting wavelength corresponding to each multi-quantum well layer decreases layer by layer from the first cyan light multi-quantum well layer to the fourth violet light multi-quantum well layer, so that the LED chip can emit cyan light, long-wave blue light, short-wave blue light and violet light. The excitation light source spans from cyan light to violet light, fully exciting the red phosphor and the green phosphor. Light of different wavelengths acts synergistically to enhance the luminous effect of the phosphor. When multiple wavelengths of light act together, the absorption spectrum of the phosphor can be more comprehensively matched. Moreover, since the light-emitting wavelength corresponding to each multi-quantum well layer of the present invention decreases layer by layer from the first cyan light multi-quantum well layer to the fourth violet light multi-quantum well layer, when the LED chip emits light along the epitaxial direction, the low-energy long-wave light emitted by the previous multi-quantum well layer is not easily absorbed by the subsequent short-wave multi-quantum well layer, effectively reducing the self-absorption loss of light, thereby effectively improving the overall excitation efficiency. At the same time, the spectral gaps left when stimulating the red and green phosphors are compensated. The resulting red and green light, along with the unabsorbed excitation light from all wavelengths that passes directly through, creates a more continuous, smoother spectrum closer to natural light, effectively improving the color rendering index. Furthermore, the proportion of blue light (particularly short-wavelength blue light) in the light emitted by the LED chip is reduced, effectively mitigating the flickering effect and eye damage caused by fluctuations in the blue light spectrum, thus protecting eye health.

[0034] Secondly, while the present invention sets the light-emitting wavelength corresponding to each multi-quantum well layer in the light-emitting layer to decrease layer by layer from the first cyan multi-quantum well layer to the fourth purple multi-quantum well layer, the band gap width of the barrier layer corresponding to each multi-quantum well layer is also decreased layer by layer. The two cooperate with each other to jointly promote the injection and effective recombination of electrons and holes. Specifically, on the one hand, since the emission wavelength corresponding to each multi-quantum well layer decreases layer by layer from the first cyan multi-quantum well layer to the fourth purple multi-quantum well layer, correspondingly, the emission energy increases layer by layer from the first cyan multi-quantum well layer to the fourth purple multi-quantum well layer, the multi-quantum well layer close to the P-type layer has higher energy, and the multi-quantum well layer close to the N-type layer has lower energy. Since electrons have relatively high mobility, they are more easily injected into the multi-quantum well layer with higher energy under the action of the electric field. Moreover, this setting can utilize the high-energy multi-quantum well layer to better bind electrons, reducing the probability of electrons leaking into the P-type layer. At the same time, the aggregation of electrons in the high-energy multi-quantum well layer will generate an electric field, which will attract holes and promote more holes to be injected into the light-emitting layer. At the same time, since holes have relatively low mobility, the setting of the multi-quantum well layer close to the N-type layer with lower energy is more conducive to the injection of holes into the multi-quantum well layer close to the N-type layer, thereby enabling carriers to be more effectively injected into each quantum well layer and improving the recombination efficiency of carriers. On the other hand, since the emission wavelength corresponding to each multi-quantum well layer decreases layer by layer from the first cyan multi-quantum well layer to the fourth violet multi-quantum well layer, the band gap width of the well layer increases layer by layer. Combined with the layer-by-layer decreasing band gap width of the barrier layer corresponding to each multi-quantum well layer, the potential barrier corresponding to each multi-quantum well layer decreases from the first cyan multi-quantum well layer to the fourth violet multi-quantum well layer. When high-mobility electrons are injected from the N-type layer into the light-emitting layer, the high-potential barrier multi-quantum well layer close to the N-type layer can increase the lateral transmission path of the electrons, slow down the transmission rate of the electrons, and increase the chance of electrons and holes meeting and recombination. Accordingly, under the influence of the electric field and their own characteristics, holes are more easily injected into the light-emitting layer and recombine with the confined electrons, thereby improving the radiation recombination efficiency and enhancing the light-emitting intensity. Therefore, by making the emission wavelength corresponding to each multi-quantum well layer and the corresponding barrier layer band gap width decrease successively from the first cyan multi-quantum well layer to the fourth purple multi-quantum well layer, the two work together to enable carriers to be more effectively injected into each quantum well layer, thereby improving the recombination efficiency of holes and electrons, thereby effectively improving the luminescence efficiency.

[0035] Thus, the present invention provides a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer, and a fourth violet multi-quantum well layer in the light-emitting layer of the LED chip, which are stacked in sequence along the epitaxial direction. The emission wavelengths and barrier band gaps corresponding to the various multi-quantum well layers decrease in sequence from the first cyan multi-quantum well layer to the fourth violet multi-quantum well layer. The LED chip can emit light in multiple different wavelengths, including cyan, long-wave blue, short-wave blue, and violet. The synergistic effect of these multiple wavelengths can more fully excite the red and green phosphors, effectively improving overall excitation efficiency. The output full-spectrum white light LED light source has a higher color rendering index, better stability, less damage to the human eye, and high luminous efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the structure of a multi-band LED chip according to an embodiment of the present invention.

[0037] Figure 2 Schematic diagram of the structure of the light-emitting layer of the LED chip according to an embodiment of the present invention.

[0038] Figure 3 Schematic diagram of the structure of a single period of the first cyan multi-quantum well layer according to an embodiment of the present invention.

[0039] Figure 4 Schematic diagram of the structure of a single period of the second long-wave blue light multi-quantum well layer according to an embodiment of the present invention.

[0040] Figure 5 Schematic diagram of the structure of a single period of the third short-wave blue light multi-quantum well layer according to an embodiment of the present invention.

[0041] Figure 6 Schematic diagram of the structure of a single period of the fourth purple multi-quantum well layer according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0043] First, see Figures 1 to 2 As shown, the present invention provides a multi-band LED chip, comprising a substrate 1 and an epitaxial layer arranged on the substrate 1, wherein the epitaxial layer comprises a buffer layer 2, an N-type layer 3, a light-emitting layer 5, an electron blocking layer 6 and a P-type layer 7 sequentially arranged along the epitaxial direction;

[0044] The light-emitting layer 5 includes a first cyan multi-quantum well layer 51, a second long-wave blue multi-quantum well layer 52, a third short-wave blue multi-quantum well layer 53 and a fourth violet multi-quantum well layer 54, which are sequentially stacked along the epitaxial direction.

[0045] The first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53 and the fourth violet multi-quantum well layer 54 are all periodic structures formed by alternating well layers and barrier layers.

[0046] The emission wavelengths of the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53 and the fourth violet multi-quantum well layer 54 decrease in sequence.

[0047] The bandgap widths of the barrier layers of the first cyan multi-quantum well layer 51 , the second long-wave blue multi-quantum well layer 52 , the third short-wave blue multi-quantum well layer 53 and the fourth violet multi-quantum well layer 54 decrease in sequence.

[0048] Among them, each multi-quantum well layer (the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54) is a periodic structure formed by alternating well layers and barrier layers. For the convenience of the following description, the well layer of the first cyan multi-quantum well layer 51 is recorded as the first well layer 51A, and the barrier layer is recorded as the first barrier layer 51B; the well layer of the second long-wave blue multi-quantum well layer 52 is recorded as the second well layer 52A, and the barrier layer is recorded as the second barrier layer 52B; the well layer of the third short-wave blue multi-quantum well layer 53 is recorded as the third well layer 53A, and the barrier layer is recorded as the third barrier layer 53B; the well layer of the fourth violet multi-quantum well layer 54 is recorded as the fourth well layer 54A, and the barrier layer is recorded as the fourth barrier layer 54B.

[0049] In the present invention, the emission wavelengths of the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decrease successively, and the bandgap widths of the barrier layers decrease successively. That is, the emission wavelength λ1 of the first cyan multi-quantum well layer 51, the emission wavelength λ2 of the second long-wave blue multi-quantum well layer 52, the emission wavelength λ3 of the third short-wave blue multi-quantum well layer 53, and the emission wavelength λ4 of the fourth violet multi-quantum well layer 54 decrease successively, λ1>λ2>λ3>λ4; the bandgap width Eg1 of the first barrier layer 51B, the bandgap width Eg2 of the second barrier layer 52B, the bandgap width Eg3 of the third barrier layer 53B, and the bandgap width Eg4 of the fourth barrier layer 54B decrease successively, Eg1>Eg2>Eg3>Eg4.

[0050] First, compared to the existing technical solution of using a single blue light as the excitation light source for the red and green mixed phosphor layer, the LED chip of the present invention can simultaneously emit multiple excitation lights of different wavelengths to cooperate with the red and green mixed phosphor layer to achieve full-spectrum white light. Specifically, the light-emitting layer 5 of the present invention includes a first cyan multi-quantum well layer 51, a second long-wave blue multi-quantum well layer 52, a third short-wave blue multi-quantum well layer 53 and a fourth purple multi-quantum well layer 54 stacked in sequence along the epitaxial direction, and the emission wavelength corresponding to each multi-quantum well layer decreases layer by layer from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54, so that the LED chip can emit cyan light, long-wave blue light, short-wave blue light and purple light, and the excitation light source spans from cyan light to purple light, fully exciting the red phosphor and green phosphor. The synergistic effect of light from different wavelengths of the phosphor enhances the luminescence of the phosphor. When multiple wavelengths of light interact, they more fully match the absorption spectrum of the phosphor. Furthermore, because the emission wavelengths corresponding to the various multi-quantum well layers of the present invention decrease from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54, when the LED chip emits light along the epitaxial direction, the low-energy, long-wavelength light emitted by the preceding multi-quantum well layer is less likely to be absorbed by the subsequent short-wavelength multi-quantum well layer, effectively reducing self-absorption losses and thus improving overall excitation efficiency. Furthermore, this compensates for the spectral gaps between the red and green phosphors when they are excited. The resulting red and green light, as well as the excitation light from the various wavelengths that are not absorbed and directly transmit, form a spectrum that is more continuous, smoother, and closer to natural light, effectively improving the color rendering index. Furthermore, the proportion of blue light (particularly short-wavelength blue light) in the light source emitted by the LED chip is reduced, effectively alleviating the flickering phenomenon and eye damage caused by fluctuations in the blue light spectrum, thereby protecting eye health.

[0051] Secondly, while the present invention sets the emission wavelength corresponding to each multi-quantum well layer in the light-emitting layer 5 to decrease layer by layer from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54, the band gap width of the barrier layer corresponding to each multi-quantum well layer is also decreased layer by layer. The two cooperate with each other to jointly promote the injection and effective recombination of electrons and holes. Specifically, on the one hand, since the emission wavelengths corresponding to the various multi-quantum well layers decrease layer by layer from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54, correspondingly, the emission energy increases layer by layer from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54, the multi-quantum well layers close to the P-type layer 7 have higher energy, and the multi-quantum well layers close to the N-type layer 3 have lower energy. Since electrons have relatively high mobility, they are more easily injected into the multi-quantum well layers with higher energy under the action of the electric field. In addition, this arrangement can utilize the high-energy multi-quantum well layers to better bind electrons, reducing the probability of electrons leaking into the P-type layer 7. At the same time, the aggregation of electrons in the high-energy multi-quantum well layers will generate an electric field, which will attract holes and promote the injection of more holes into the light-emitting layer 5. At the same time, since holes have relatively low mobility, the arrangement of the multi-quantum well layers close to the N-type layer 3 with lower energy is more conducive to the injection of holes into the multi-quantum well layers close to the N-type layer 3, thereby promoting more efficient injection of carriers into each quantum well layer and improving the recombination efficiency of carriers. On the other hand, since the emission wavelength corresponding to each multi-quantum well layer decreases layer by layer from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54, the band gap width of the well layer increases layer by layer. Combined with the layer-by-layer decreasing band gap width of the barrier layer corresponding to each multi-quantum well layer, the potential barrier corresponding to each multi-quantum well layer decreases from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54. When high-mobility electrons are injected from the N-type layer 3 into the light-emitting layer 5, the high-potential barrier multi-quantum well layer close to the N-type layer 3 can increase the lateral transmission path of the electrons, slow down the transmission rate of the electrons, and increase the chance of electrons and holes meeting and recombination. Accordingly, under the influence of the electric field and their own characteristics, holes are more easily injected into the light-emitting layer 5 and recombine with the confined electrons, thereby improving the radiation recombination efficiency and enhancing the light-emitting intensity. Therefore, by making the emission wavelength corresponding to each multi-quantum well layer and the corresponding barrier layer band gap width decrease successively from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54, the two work together to enable carriers to be more effectively injected into each quantum well layer, thereby improving the recombination efficiency of holes and electrons, thereby effectively improving the luminescence efficiency.

[0052] Thus, the present invention provides a first cyan multi-quantum well layer 51, a second long-wave blue multi-quantum well layer 52, a third short-wave blue multi-quantum well layer 53, and a fourth violet multi-quantum well layer 54 in the light-emitting layer 5 of the LED chip, which are sequentially stacked along the epitaxial direction. The emission wavelengths and barrier band gaps corresponding to the various multi-quantum well layers decrease in sequence from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54. The LED chip can emit light in multiple different wavelengths, including cyan, long-wave blue, short-wave blue, and violet. The synergistic effect of these different wavelengths can more fully excite the red and green phosphors, effectively improving overall excitation efficiency. The output full-spectrum white LED light source has a higher color rendering index, better stability, less damage to the human eye, and high luminous efficiency.

[0053] In some embodiments, the emission wavelength of the first cyan multi-quantum well layer 51 is 490nm~500nm, the emission wavelength of the second long-wave blue multi-quantum well layer 52 is 460nm~480nm, the emission wavelength of the third short-wave blue multi-quantum well layer 53 is 445nm~460nm, and the emission wavelength of the fourth purple multi-quantum well layer 54 is 430nm~445nm.

[0054] By regulating the emission wavelengths of each multi-quantum well layer in the light-emitting layer 5, light from different wavelengths works synergistically to fully excite the red and green phosphors, more comprehensively matching their absorption spectra. This also compensates for spectral gaps left when the red and green phosphors are excited. The resulting red and green light, as well as the excitation light from wavelengths that is not absorbed and passes through, creates a more continuous, smoother spectrum that more closely resembles natural light, effectively improving the color rendering index. Furthermore, the proportion of blue light (particularly short-wavelength blue light) in the light emitted by the LED chip is reduced, effectively mitigating flickering and eye damage caused by fluctuations in the blue light spectrum, thus protecting eye health.

[0055] Exemplarily, the light emission wavelength λ1 of the first cyan multi-quantum well layer 51 is 490 nm, 492 nm, 495 nm, 498 nm or 500 nm, but is not limited thereto.

[0056] Illustratively, the light emission wavelength λ2 of the second long-wave blue multi-quantum well layer 52 is 460 nm, 462 nm, 465 nm, 468 nm, 470 nm, 472 nm, 475 nm, 478 nm or 480 nm, but is not limited thereto.

[0057] Illustratively, the light emission wavelength λ3 of the third short-wave blue multi-quantum well layer 53 is 445 nm, 448 nm, 449 nm, 450 nm, 452 nm, 455 nm, 458 nm or 460 nm, but is not limited thereto.

[0058] Illustratively, the light emission wavelength λ4 of the fourth purple multi-quantum well layer 54 is 430 nm, 432 nm, 435 nm, 438 nm, 440 nm, 442 nm, or 445 nm, but is not limited thereto.

[0059] It can be understood that there is an overlapping area in the emission wavelength value ranges corresponding to the above-mentioned multi-quantum well layers. During preparation, it is only necessary to ensure that the emission wavelengths decrease successively between the four multi-quantum well layers from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54.

[0060] In some embodiments, see Figures 3 to 6 As shown, each barrier layer (i.e., the first barrier layer 51B, the second barrier layer 52B, the third barrier layer 53B, and the fourth barrier layer 54B) includes a Si-doped front GaN layer, an AlGaN layer not intentionally doped with Si, and a Si-doped back GaN layer sequentially stacked along the epitaxial direction.

[0061] Moreover, the Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53 and the fourth violet multi-quantum well layer 54 decreases successively, and the total thickness of a single barrier layer decreases successively.

[0062] By making the Al component content of the AlGaN layer that is not intentionally doped with Si corresponding to each multi-quantum well layer decrease layer by layer from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54, and making the total thickness of the barrier layer corresponding to each multi-quantum well layer decrease in sequence, on the one hand, a thin barrier structure with a low barrier height can be formed on the side of the light-emitting layer 5 close to the P-type layer 7, wherein the lower barrier height makes it easier for holes to be injected into the light-emitting layer 5, and at the same time, the thin barrier structure can shorten the distance for holes to cross the barrier layer, further reducing the difficulty of crossing, and increasing the hole concentration of the light-emitting layer 5, thereby making the side close to the N-type layer 3 The multi-quantum well layer also has sufficient holes to participate in the recombination; on the other hand, a thick barrier structure with a high barrier height can be formed on the side of the light-emitting layer 5 close to the N-type layer 3, wherein the higher barrier height can effectively increase the lateral transmission path of electrons, slow down the transmission rate of electrons, increase the chance of electrons and holes meeting and recombination, and effectively prevent electron overflow. Therefore, by combining the thin barrier structure with a low barrier height with the thick barrier structure with a high barrier height, the two work together to enable carriers to be more effectively injected into each quantum well layer, thereby improving the recombination efficiency of holes and electrons, thereby effectively improving the luminescence efficiency.

[0063] Among them, see Figures 3 to 6As shown, for the convenience of the following description, the Si-doped front GaN layer of the first barrier layer 51B is recorded as the first front GaN layer 511, the AlGaN layer not intentionally doped with Si is recorded as the first AlGaN layer 512, and the Si-doped back GaN layer is recorded as the first back GaN layer 513; the Si-doped front GaN layer of the second barrier layer 52B is recorded as the second front GaN layer 521, the AlGaN layer not intentionally doped with Si is recorded as the second AlGaN layer 522, and the Si-doped back GaN layer is recorded as the second back Ga N layer 523; the Si-doped front GaN layer of the third barrier layer 53B is recorded as the third front GaN layer 531, the AlGaN layer not intentionally doped with Si is recorded as the third AlGaN layer 532, and the Si-doped back GaN layer is recorded as the third back GaN layer 533; the Si-doped front GaN layer of the fourth barrier layer 54B is recorded as the fourth front GaN layer 541, the AlGaN layer not intentionally doped with Si is recorded as the fourth AlGaN layer 542, and the Si-doped back GaN layer is recorded as the fourth back GaN layer 543.

[0064] In the present invention, the Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decreases in sequence, and the total thickness of the single barrier layer decreases in sequence, that is:

[0065] The Al content x1 of the first AlGaN layer 512, the Al content x2 of the second AlGaN layer 522, the Al content x3 of the third AlGaN layer 532, and the Al content x4 of the fourth AlGaN layer 542 decrease in sequence, x1>x2>x3>x4;

[0066] The total thickness H1 of the single first barrier layer 51B, the total thickness H2 of the single second barrier layer 52B, the total thickness H3 of the single third barrier layer 53B, and the total thickness H4 of the single fourth barrier layer 54B decrease in sequence: H1>H2>H3>H4.

[0067] In some embodiments, the Al component contents of the AlGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 are x1, x2, x3, and x4, respectively, where 0.03≤x1≤0.15, 0.02≤x2≤0.12, 0.01≤x3≤0.1, and 0<x4≤0.08.

[0068] By adjusting the Al component content in each multi-quantum well layer, a decreasing trend is formed between the barrier layers of each multi-quantum well layer from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54. The Al component content should not be too high, otherwise it is easy to increase the defects of the material layer. The Al component content should not be too low, otherwise it is difficult to form a sufficient barrier height.

[0069] Illustratively, x1 is 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15, but is not limited thereto.

[0070] Illustratively, x2 is 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11 or 0.12, but is not limited thereto.

[0071] Illustratively, x3 is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, but is not limited thereto.

[0072] Illustratively, x4 is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07 or 0.08, but is not limited thereto.

[0073] It can be understood that there is an overlapping area in the value ranges of the above-mentioned x1, x2, x3 and x4. During preparation, it is only necessary to ensure that the Al component content of the AlGaN layer that is not intentionally doped with Si corresponding to the four multi-quantum well layers from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54 decreases in sequence.

[0074] In some embodiments, the growth temperatures of the Si-doped front GaN layer and the Si-doped back GaN layer of the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 are increased in sequence, and the Si doping concentration is decreased in sequence. The total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is decreased in sequence, and the single layer thickness of each AlGaN layer that is not intentionally doped with Si is the same and the growth temperature is the same, that is:

[0075] The growth temperature T1 of the first front GaN layer 511 and the first back GaN layer 513, the growth temperature T2 of the second front GaN layer 521 and the second back GaN layer 523, the growth temperature T3 of the third front GaN layer 531 and the third back GaN layer 533, and the growth temperature T4 of the fourth front GaN layer 541 and the fourth back GaN layer 543 increase in sequence, T1<T2<T3<T4;

[0076] The Si doping concentration N1 of the first front GaN layer 511 and the first back GaN layer 513, the Si doping concentration N2 of the second front GaN layer 521 and the second back GaN layer 523, the Si doping concentration N3 of the third front GaN layer 531 and the third back GaN layer 533, and the Si doping concentration N4 of the fourth front GaN layer 541 and the fourth back GaN layer 543 are in a decreasing trend, N1>N2>N3>N4;

[0077] The total thickness h1 of the first front GaN layer 511 and the first back GaN layer 513 in the single first barrier layer 51B, the total thickness h2 of the second front GaN layer 521 and the second back GaN layer 523 in the single second barrier layer 52B, the total thickness h3 of the third front GaN layer 531 and the third back GaN layer 533 in the single third barrier layer 53B, and the total thickness h4 of the fourth front GaN layer 541 and the fourth back GaN layer 543 in the single fourth barrier layer 54B show a decreasing trend, i.e., h1>h2>h3>h4.

[0078] The first AlGaN layer 512 , the second AlGaN layer 522 , the third AlGaN layer 532 , and the fourth AlGaN layer 542 have the same single layer thickness and are grown at the same temperature.

[0079] Among them, when each multi-quantum well layer uses an InGaN layer as a well layer, since the emission wavelength corresponding to each multi-quantum well layer decreases from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54, the content of the In component in the well layer of each corresponding multi-quantum well layer decreases accordingly, and the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer corresponding to each multi-quantum well layer increases from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54. This can ensure that the In component in the well layer of each multi-quantum well layer is smoothly incorporated while improving the overall quality of the light-emitting layer 5, thereby benefiting In order to improve the luminous efficiency and luminous stability, the Si doping concentration of the Si-doped front GaN layer and the Si-doped back GaN layer corresponding to each multi-quantum well layer decreases successively from the first cyan multi-quantum well layer 51 to the fourth purple multi-quantum well layer 54. Each multi-quantum well layer can be supplemented with an appropriate amount of electrons, optimize the distribution of carriers in the entire multi-band light-emitting structure, and improve the luminous efficiency of each band. At the same time, the lower Si doping concentration can reduce the lattice distortion caused by excessive Si doping concentration. Combined with the above-mentioned growth temperature increasing setting, the overall quality of the light-emitting layer 5 is improved, which is conducive to further improving the luminous efficiency and luminous stability.

[0080] In some embodiments, in the first cyan multi-quantum well layer 51, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 820°C to 913°C, and the Si doping concentration is 1.5×10 17 / cm 3 ~7.9×1017 / cm 3 In the second long-wave blue multi-quantum well layer 52, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 825°C~918°C, and the Si doping concentration is 1.3×10 17 / cm 3 ~7.3×10 17 / cm 3 In the third short-wave blue multi-quantum well layer 53, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 830°C~923°C, and the Si doping concentration is 1.1×10 17 / cm 3 ~6.7×10 17 / cm 3 In the fourth purple multi-quantum well layer 54, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 835°C~928°C, and the Si doping concentration is 0.9×10 17 / cm 3 ~6.3×10 17 / cm 3 .

[0081] In each multi-quantum well layer, the Si doping concentration in the Si-doped front GaN layer and the Si-doped back GaN layer should not be too high (especially the Si-doped front GaN layer and the Si-doped back GaN layer in the fourth purple multi-quantum well layer 54), otherwise it will easily lead to excessive electron injection, which will easily increase the risk of electron-hole recombination imbalance and the risk of electron overflow.

[0082] Illustratively, the growth temperature T1 of the first front GaN layer 511 and the first back GaN layer 513 may be 820°C, 825°C, 830°C, 835°C, 840°C, 845°C, 850°C, 855°C, 860°C, 865°C, 870°C, 875°C, 880°C, 885°C, 890°C, 895°C, 900°C, 910°C or 913°C, but is not limited thereto.

[0083] Illustratively, the growth temperature T2 of the second front GaN layer 521 and the second back GaN layer 523 may be 825°C, 830°C, 835°C, 840°C, 845°C, 850°C, 855°C, 860°C, 865°C, 870°C, 875°C, 880°C, 885°C, 890°C, 895°C, 900°C, 910°C, 915°C or 918°C, but is not limited thereto.

[0084] Illustratively, the growth temperature T3 of the third front GaN layer 531 and the third back GaN layer 533 may be 830°C, 835°C, 840°C, 845°C, 850°C, 855°C, 860°C, 865°C, 870°C, 875°C, 880°C, 885°C, 890°C, 895°C, 900°C, 910°C, 915°C, 920°C or 923°C, but is not limited thereto.

[0085] Illustratively, the growth temperature T4 of the fourth front GaN layer 541 and the fourth back GaN layer 543 may be 835°C, 840°C, 845°C, 850°C, 855°C, 860°C, 865°C, 870°C, 875°C, 880°C, 885°C, 890°C, 895°C, 900°C, 910°C, 915°C, 920°C, 925°C or 928°C, but is not limited thereto.

[0086] For example, the Si doping concentration N1 of the first front GaN layer 511 and the first back GaN layer 513 may be 1.5×10 17 / cm 3 , 1.8×10 17 / cm 3 , 2.0×10 17 / cm 3 , 2.2×10 17 / cm 3 , 2.5×10 17 / cm 3 , 2.8×10 17 / cm 3 , 3.0×10 17 / cm 3 , 3.2×10 17 / cm 3 , 3.5×10 17 / cm 3 , 3.8×10 17 / cm 3 , 4.0×10 17 / cm 3 , 4.2×10 17 / cm 3 , 4.5×10 17 / cm 3 , 4.8×10 17 / cm 3 , 5.0×10 17 / cm 3 , 5.2×10 17 / cm 3 , 5.5×10 17 / cm 3 , 5.8×10 17 / cm3 , 6.0×10 17 / cm 3 , 6.2×10 17 / cm 3 , 6.5×10 17 / cm 3 , 6.8×10 17 / cm 3 , 7.0×10 17 / cm 3 , 7.2×10 17 / cm 3 , 7.5×10 17 / cm 3 , 7.8×10 17 / cm 3 or 7.9×10 17 / cm 3 , but not limited to this.

[0087] For example, the Si doping concentration N2 of the second front GaN layer 521 and the second back GaN layer 523 may be 1.3×10 17 / cm 3 , 1.5×10 17 / cm 3 , 1.8×10 17 / cm 3 , 2.0×10 17 / cm 3 , 2.2×10 17 / cm 3 , 2.5×10 17 / cm 3 , 2.8×10 17 / cm 3 , 3.0×10 17 / cm 3 , 3.2×10 17 / cm 3 , 3.5×10 17 / cm 3 , 3.8×10 17 / cm 3 , 4.0×10 17 / cm 3 , 4.2×10 17 / cm 3 , 4.5×10 17 / cm 3 , 4.8×10 17 / cm 3 , 5.0×10 17 / cm 3 , 5.2×10 17 / cm 3 , 5.5×10 17 / cm 3 , 5.8×10 17 / cm 3 , 6.0×10 17 / cm 3 , 6.2×10 17 / cm 3 , 6.5×10 17 / cm 3 , 6.8×10 17 / cm 3 , 7.0×10 17 / cm 3 , 7.2×10 17 / cm 3 or 7.3 × 10 17 / cm 3 , but not limited to this.

[0088] For example, the Si doping concentration N3 of the third front GaN layer 531 and the third back GaN layer 533 may be 1.1×10 17 / cm 3 , 1.3×10 17 / cm 3 , 1.5×10 17 / cm 3 , 1.8×10 17 / cm 3 , 2.0×10 17 / cm 3 , 2.2×10 17 / cm 3 , 2.5×10 17 / cm 3 , 2.8×10 17 / cm 3 , 3.0×10 17 / cm 3 , 3.2×10 17 / cm 3 , 3.5×10 17 / cm 3 , 3.8×10 17 / cm 3 , 4.0×10 17 / cm 3 , 4.2×10 17 / cm 3 , 4.5×10 17 / cm 3 , 4.8×10 17 / cm 3 , 5.0×1017 / cm 3 , 5.2×10 17 / cm 3 , 5.5×10 17 / cm 3 , 5.8×10 17 / cm 3 , 6.0×10 17 / cm 3 , 6.2×10 17 / cm 3 , 6.5×10 17 / cm 3 or 6.7×10 17 / cm 3 , but not limited to this.

[0089] For example, the Si doping concentration N4 of the fourth front GaN layer 541 and the fourth back GaN layer 543 may be 0.9×10 17 / cm 3 , 1.1×10 17 / cm 3 , 1.3×10 17 / cm 3 , 1.5×10 17 / cm 3 , 1.8×10 17 / cm 3 , 2.0×10 17 / cm 3 , 2.2×10 17 / cm 3 , 2.5×10 17 / cm 3 , 2.8×10 17 / cm 3 , 3.0×10 17 / cm 3 , 3.2×10 17 / cm 3 , 3.5×10 17 / cm 3 , 3.8×10 17 / cm 3 , 4.0×10 17 / cm 3 , 4.2×10 17 / cm 3 , 4.5×10 17 / cm 3 , 4.8×10 17 / cm 3 , 5.0×10 17 / cm 3, 5.2×10 17 / cm 3 , 5.5×10 17 / cm 3 , 5.8×10 17 / cm 3 , 6.0×10 17 / cm 3 , 6.2×10 17 / cm 3 or 6.3 × 10 17 / cm 3 , but not limited to this.

[0090] In some embodiments, in the first cyan multi-quantum well layer 51, the total thickness h1 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 6 nm to 12 nm; in the second long-wave blue multi-quantum well layer 52, the total thickness h2 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 5.2 nm to 11.2 nm; in the third short-wave blue multi-quantum well layer 53, the total thickness h3 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4.6 nm to 10.6 nm; in the fourth violet multi-quantum well layer 54, the total thickness h4 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4 nm to 10 nm.

[0091] Exemplarily, the total thickness h1 of the first front GaN layer 511 and the first back GaN layer 513 in a single first barrier layer 51B is 6nm, 6.2nm, 6.5nm, 6.8nm, 7nm, 7.2nm, 7.5nm, 7.8nm, 8nm, 8.2nm, 8.5nm, 8.8nm, 9nm, 9.2nm, 9.5nm, 9.8nm, 10nm, 10.2nm, 10.5nm, 10.8nm, 11nm, 11.2nm, 11.5nm, 11.8nm or 12nm, but is not limited thereto.

[0092] Exemplarily, the total thickness h2 of the second front GaN layer 521 and the second back GaN layer 523 in a single second barrier layer 52B is 5.2nm, 5.5nm, 5.8nm, 6nm, 6.2nm, 6.5nm, 6.8nm, 7nm, 7.2nm, 7.5nm, 7.8nm, 8nm, 8.2nm, 8.5nm, 8.8nm, 9nm, 9.2nm, 9.5nm, 9.8nm, 10nm, 10.2nm, 10.5nm, 10.8nm, 11nm or 11.2nm, but is not limited thereto.

[0093] Exemplarily, the total thickness h3 of the third front GaN layer 531 and the third back GaN layer 533 in a single third barrier layer 53B is 4.6 nm, 4.8 nm, 5 nm, 5.2 nm, 5.5 nm, 5.8 nm, 6 nm, 6.2 nm, 6.5 nm, 6.8 nm, 7 nm, 7.2 nm, 7.5 nm, 7.8 nm, 8 nm, 8.2 nm, 8.5 nm, 8.8 nm, 9 nm, 9.2 nm, 9.5 nm, 9.8 nm, 10 nm, 10.2 nm or 10.6 nm, but is not limited thereto.

[0094] Exemplarily, the total thickness h4 of the fourth front GaN layer 541 and the fourth back GaN layer 543 in a single fourth barrier layer 54B is 4nm, 4.2nm, 4.5nm, 4.8nm, 5nm, 5.2nm, 5.5nm, 5.8nm, 6nm, 6.2nm, 6.5nm, 6.8nm, 7nm, 7.2nm, 7.5nm, 7.8nm, 8nm, 8.2nm, 8.5nm, 8.8nm, 9nm, 9.2nm, 9.5nm, 9.8nm or 10nm, but is not limited thereto.

[0095] In some embodiments, within each multi-quantum well layer, the thickness of the Si-doped front GaN layer and the thickness of the Si-doped back GaN layer within a single barrier layer are the same.

[0096] In some embodiments, the thickness of each AlGaN layer not intentionally doped with Si is 1 nm to 5 nm, and the growth temperature is 780° C. to 928° C.

[0097] Illustratively, the single layer thickness of each AlGaN layer that is not intentionally doped with Si (the first AlGaN layer 512, the second AlGaN layer 522, the third AlGaN layer 532, and the fourth AlGaN layer 542) is 1 nm, 1.2 nm, 1.5 nm, 1.8 nm, 2 nm, 2.2 nm, 2.5 nm, 2.8 nm, 3 nm, 3.2 nm, 3.5 nm, 3.8 nm, 4 nm, 4.2 nm, 4.5 nm, 4.8 nm, or 5 nm, but is not limited thereto, and the growth temperature is 780°C, 785°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, or 928°C, but is not limited thereto.

[0098] In some embodiments, each well layer includes an InGaN layer that is not intentionally doped with Si, and the In component content of the InGaN layer that is not intentionally doped with Si in the first cyan light multi-quantum well layer 51, the second long-wave blue light multi-quantum well layer 52, the third short-wave blue light multi-quantum well layer 53 and the fourth purple light multi-quantum well layer 54 decreases successively, and the growth temperature increases successively. By adjusting the In component in the corresponding well layer of each multi-quantum well layer, adjusting the emission wavelength, and setting the growth temperature in a sequentially increasing manner, it is beneficial to improve the overall quality of the light-emitting layer 5 while ensuring the stability of the In component, thereby further improving the luminous efficiency.

[0099] In some embodiments, in the first cyan multi-quantum well layer 51, the In component content of the InGaN layer that is not intentionally doped with Si is 0.19~0.21; in the second long-wave blue multi-quantum well layer 52, the In component content of the InGaN layer that is not intentionally doped with Si is 0.16~0.19; in the third short-wave blue multi-quantum well layer 53, the In component content of the InGaN layer that is not intentionally doped with Si is 0.13~0.16; in the fourth purple multi-quantum well layer 54, the In component content of the InGaN layer that is not intentionally doped with Si is 0.1~0.13.

[0100] In some embodiments, see Figure 1 As shown, a low-temperature stress release layer 4 may be further provided between the N-type layer 3 and the light-emitting layer 5 .

[0101] In some embodiments, the number of periods of the first cyan multi-quantum well layer 51 is 1 to 3, the number of periods of the second long-wave blue multi-quantum well layer 52 is 2 to 5, the number of periods of the third short-wave blue multi-quantum well layer 53 is 2 to 5, and the number of periods of the fourth purple multi-quantum well layer 54 is 1 to 3.

[0102] Secondly, see Figure 1 and Figure 2 As shown, the present invention provides a method for preparing a multi-band LED chip, comprising:

[0103] S100. Providing a substrate 1;

[0104] S200. An epitaxial layer is deposited on a substrate 1, the epitaxial layer comprising a buffer layer 2, an N-type layer 3, a light-emitting layer 5, an electron blocking layer 6 and a P-type layer 7 sequentially arranged along the epitaxial direction;

[0105] The light-emitting layer 5 includes a first cyan multi-quantum well layer 51, a second long-wave blue multi-quantum well layer 52, a third short-wave blue multi-quantum well layer 53 and a fourth violet multi-quantum well layer 54, which are sequentially stacked along the epitaxial direction.

[0106] The first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53 and the fourth violet multi-quantum well layer 54 are all periodic structures formed by alternating well layers and barrier layers.

[0107] The emission wavelengths of the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53 and the fourth violet multi-quantum well layer 54 decrease in sequence.

[0108] The bandgap widths of the barrier layers of the first cyan multi-quantum well layer 51 , the second long-wave blue multi-quantum well layer 52 , the third short-wave blue multi-quantum well layer 53 and the fourth violet multi-quantum well layer 54 decrease in sequence.

[0109] In some embodiments, the emission wavelength of the first cyan multi-quantum well layer 51 is 490nm~500nm, the emission wavelength of the second long-wave blue multi-quantum well layer 52 is 460nm~480nm, the emission wavelength of the third short-wave blue multi-quantum well layer 53 is 445nm~460nm, and the emission wavelength of the fourth purple multi-quantum well layer 54 is 430nm~445nm.

[0110] In some embodiments, each barrier layer includes a Si-doped front GaN layer, an AlGaN layer not intentionally doped with Si, and a Si-doped back GaN layer stacked sequentially along the epitaxial direction, and the Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer 51, the second long-wave blue multi-quantum well layer 52, the third short-wave blue multi-quantum well layer 53, and the fourth purple multi-quantum well layer 54 decreases sequentially, and the total thickness of the barrier layer decreases sequentially.

[0111] Furthermore, the present invention provides a white light LED light source, comprising a fluorescent adhesive layer and the above-mentioned LED chip, wherein the fluorescent adhesive layer comprises red fluorescent powder and green fluorescent powder.

[0112] It can be understood that the red phosphor refers to a phosphor that emits red light after being excited, and the green phosphor refers to a phosphor that emits green light after being excited.

[0113] For example, the red phosphor can be at least one of a nitride red phosphor, a nitrogen oxide red phosphor or a fluoride red phosphor, for example, CaAlSiN3:Eu 2+ 、Sr2Si5N8:Eu 2+ 、K2SiF6:Mn 4+ .

[0114] For example, the green phosphor can be at least one of a silicate green phosphor, a nitrogen oxide green phosphor or a garnet structure green phosphor, for example, β-SiAlON:Eu 2+ 、Lu3Al5O 12 :Ce3+ .

[0115] The LED chip of the present invention can emit light of multiple different wavelengths, such as cyan light, long-wave blue light, short-wave blue light and violet light. The synergistic effect of light of multiple different wavelengths can more fully excite red phosphor and green phosphor, effectively improving the overall excitation efficiency. The output full-spectrum white light LED light source has a higher color rendering index, better stability, less damage to the human eye, and high luminous efficiency.

[0116] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0117] Example 1

[0118] First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer includes a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer sequentially disposed along the epitaxial direction;

[0119] The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer sequentially stacked along the epitaxial direction;

[0120] The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers.

[0121] The emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively, and the bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively.

[0122] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 490nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 460nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 445nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430nm.

[0123] In this embodiment, the barrier layer of each multi-quantum well layer includes a Si-doped front GaN layer, an AlGaN layer not intentionally doped with Si, and a Si-doped back GaN layer stacked in sequence along the epitaxial direction.

[0124] The Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decreases successively, and the total thickness of the single barrier layer decreases successively.

[0125] In this embodiment, the Al component contents of the AlGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are x1, x2, x3, and x4, respectively, where x1 is 0.15, x2 is 0.12, x3 is 0.1, and x4 is 0.08.

[0126] In this embodiment, the growth temperatures of the Si-doped front GaN layer and the Si-doped back GaN layer of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer increase successively, the Si doping concentration decreases successively, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer decreases successively, and the single layer thickness of each AlGaN layer that is not intentionally doped with Si is the same and the growth temperature is the same.

[0127] In this embodiment, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer in the first cyan multi-quantum well layer is 820°C, and the Si doping concentration is 4×10 17 / cm 3 In the second long-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 830°C, and the Si doping concentration is 3×10 17 / cm 3 In the third short-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 850°C, and the Si doping concentration is 2×10 17 / cm 3 In the fourth purple multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 880°C, and the Si doping concentration is 1×10 17 / cm 3 .

[0128] In this embodiment, in the first cyan multi-quantum well layer, the total thickness h1 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 10 nm; in the second long-wave blue multi-quantum well layer, the total thickness h2 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 8 nm; in the third short-wave blue multi-quantum well layer, the total thickness h3 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 6 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4 nm.

[0129] In this embodiment, the thickness of each AlGaN layer not intentionally doped with Si is 3 nm, and the growth temperature is 820°C.

[0130] In this embodiment, the well layers of each multi-quantum well layer include InGaN layers that are not intentionally doped with Si, and the In component content of the InGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth purple multi-quantum well layer decreases successively, and the growth temperature increases successively.

[0131] In this embodiment, the period number of the first cyan multi-quantum well layer is 1, the period number of the second long-wave blue multi-quantum well layer is 2, the period number of the third short-wave blue multi-quantum well layer is 2, and the period number of the fourth violet multi-quantum well layer is 1.

[0132] Furthermore, this embodiment provides a white light LED light source, including a fluorescent adhesive layer and the above-mentioned LED chip, wherein the fluorescent adhesive layer includes red fluorescent powder and green fluorescent powder.

[0133] Example 2

[0134] First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer includes a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer sequentially disposed along the epitaxial direction;

[0135] The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer sequentially stacked along the epitaxial direction;

[0136] The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers.

[0137] The emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively, and the bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively.

[0138] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 500nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 480nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 460nm, and the emission wavelength of the fourth purple multi-quantum well layer is 445nm.

[0139] In this embodiment, the barrier layer of each multi-quantum well layer includes a Si-doped front GaN layer, an AlGaN layer not intentionally doped with Si, and a Si-doped back GaN layer stacked in sequence along the epitaxial direction.

[0140] The Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decreases successively, and the total thickness of the single barrier layer decreases successively.

[0141] In this embodiment, the Al component contents of the AlGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are x1, x2, x3, and x4, respectively, where x1 is 0.03, x2 is 0.02, x3 is 0.01, and x4 is 0.005.

[0142] In this embodiment, the growth temperatures of the Si-doped front GaN layer and the Si-doped back GaN layer of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer increase successively, the Si doping concentration decreases successively, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer decreases successively, and the single layer thickness of each AlGaN layer that is not intentionally doped with Si is the same and the growth temperature is the same.

[0143] In this embodiment, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer in the first cyan multi-quantum well layer is 820°C, and the Si doping concentration is 4×10 17 / cm 3 In the second long-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 830°C, and the Si doping concentration is 3×10 17 / cm 3 In the third short-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 850°C, and the Si doping concentration is 2×10 17 / cm 3 In the fourth purple multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 880°C, and the Si doping concentration is 1×10 17 / cm 3 .

[0144] In this embodiment, in the first cyan multi-quantum well layer, the total thickness h1 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 10 nm; in the second long-wave blue multi-quantum well layer, the total thickness h2 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 8 nm; in the third short-wave blue multi-quantum well layer, the total thickness h3 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 6 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4 nm.

[0145] In this embodiment, the thickness of each AlGaN layer not intentionally doped with Si is 3 nm, and the growth temperature is 820°C.

[0146] In this embodiment, the well layers of each multi-quantum well layer include InGaN layers that are not intentionally doped with Si, and the In component content of the InGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth purple multi-quantum well layer decreases successively, and the growth temperature increases successively.

[0147] In this embodiment, the period number of the first cyan multi-quantum well layer is 1, the period number of the second long-wave blue multi-quantum well layer is 2, the period number of the third short-wave blue multi-quantum well layer is 2, and the period number of the fourth violet multi-quantum well layer is 1.

[0148] Furthermore, this embodiment provides a white light LED light source, including a fluorescent adhesive layer and the above-mentioned LED chip, wherein the fluorescent adhesive layer includes red fluorescent powder and green fluorescent powder.

[0149] Example 3

[0150] First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer includes a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer sequentially disposed along the epitaxial direction;

[0151] The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer sequentially stacked along the epitaxial direction;

[0152] The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers, and the emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively, and the bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively.

[0153] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 495nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 470nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 450nm, and the emission wavelength of the fourth violet multi-quantum well layer is 440nm.

[0154] In this embodiment, the barrier layer of each multi-quantum well layer includes a Si-doped front GaN layer, an AlGaN layer not intentionally doped with Si, and a Si-doped back GaN layer stacked in sequence along the epitaxial direction.

[0155] The Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decreases successively, and the total thickness of the single barrier layer decreases successively.

[0156] In this embodiment, the Al component contents of the AlGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are x1, x2, x3, and x4, respectively, where x1 is 0.1, x2 is 0.08, x3 is 0.06, and x4 is 0.04.

[0157] In this embodiment, the growth temperatures of the Si-doped front GaN layer and the Si-doped back GaN layer of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer increase successively, the Si doping concentration decreases successively, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer decreases successively, and the single layer thickness of each AlGaN layer that is not intentionally doped with Si is the same and the growth temperature is the same.

[0158] In this embodiment, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer in the first cyan multi-quantum well layer is 820°C, and the Si doping concentration is 4×10 17 / cm 3 In the second long-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 830°C, and the Si doping concentration is 3×10 17 / cm 3 In the third short-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 850°C, and the Si doping concentration is 2×10 17 / cm 3 In the fourth purple multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 880°C, and the Si doping concentration is 1×10 17 / cm 3 .

[0159] In this embodiment, in the first cyan multi-quantum well layer, the total thickness h1 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 10 nm; in the second long-wave blue multi-quantum well layer, the total thickness h2 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 8 nm; in the third short-wave blue multi-quantum well layer, the total thickness h3 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 6 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4 nm.

[0160] In this embodiment, the thickness of each AlGaN layer not intentionally doped with Si is 3 nm, and the growth temperature is 820°C.

[0161] In this embodiment, the well layers of each multi-quantum well layer include InGaN layers that are not intentionally doped with Si, and the In component content of the InGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth purple multi-quantum well layer decreases successively, and the growth temperature increases successively.

[0162] In this embodiment, the period number of the first cyan multi-quantum well layer is 1, the period number of the second long-wave blue multi-quantum well layer is 2, the period number of the third short-wave blue multi-quantum well layer is 2, and the period number of the fourth violet multi-quantum well layer is 1.

[0163] Furthermore, this embodiment provides a white light LED light source, including a fluorescent adhesive layer and the above-mentioned LED chip, wherein the fluorescent adhesive layer includes red fluorescent powder and green fluorescent powder.

[0164] Example 4

[0165] First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer includes a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer sequentially disposed along the epitaxial direction;

[0166] The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer sequentially stacked along the epitaxial direction;

[0167] The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers.

[0168] The emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively, and the bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively.

[0169] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 490nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 460nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 445nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430nm.

[0170] In this embodiment, the barrier layer of each multi-quantum well layer includes a Si-doped front GaN layer, an AlGaN layer not intentionally doped with Si, and a Si-doped back GaN layer stacked in sequence along the epitaxial direction.

[0171] The Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decreases successively, and the total thickness of the single barrier layer decreases successively.

[0172] In this embodiment, the Al component contents of the AlGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are x1, x2, x3, and x4, respectively, where x1 is 0.15, x2 is 0.12, x3 is 0.1, and x4 is 0.08.

[0173] In this embodiment, the growth temperatures of the Si-doped front GaN layer and the Si-doped back GaN layer of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer increase successively, the Si doping concentration decreases successively, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer decreases successively, and the single layer thickness of each AlGaN layer that is not intentionally doped with Si is the same and the growth temperature is the same.

[0174] In this embodiment, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer in the first cyan multi-quantum well layer is 820°C, and the Si doping concentration is 4×10 17 / cm 3 In the second long-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 830°C, and the Si doping concentration is 3×10 17 / cm 3 In the third short-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 850°C, and the Si doping concentration is 2×10 17 / cm 3 In the fourth purple multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 880°C, and the Si doping concentration is 1×10 17 / cm 3 .

[0175] In this embodiment, in the first cyan multi-quantum well layer, the total thickness h1 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 10 nm; in the second long-wave blue multi-quantum well layer, the total thickness h2 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 10 nm; in the third short-wave blue multi-quantum well layer, the total thickness h3 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 10 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 10 nm.

[0176] In this embodiment, the thickness of each AlGaN layer not intentionally doped with Si is 3 nm, and the growth temperature is 820°C.

[0177] In this embodiment, the well layers of each multi-quantum well layer include InGaN layers that are not intentionally doped with Si, and the In component content of the InGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth purple multi-quantum well layer decreases successively, and the growth temperature increases successively.

[0178] In this embodiment, the period number of the first cyan multi-quantum well layer is 1, the period number of the second long-wave blue multi-quantum well layer is 2, the period number of the third short-wave blue multi-quantum well layer is 2, and the period number of the fourth violet multi-quantum well layer is 1.

[0179] Furthermore, this embodiment provides a white light LED light source, including a fluorescent adhesive layer and the above-mentioned LED chip, wherein the fluorescent adhesive layer includes red fluorescent powder and green fluorescent powder.

[0180] Example 5

[0181] First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate, wherein the epitaxial layer includes a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer sequentially disposed along the epitaxial direction;

[0182] The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer sequentially stacked along the epitaxial direction;

[0183] The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers.

[0184] The emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively, and the bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decrease successively.

[0185] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 490nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 460nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 445nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430nm.

[0186] In this embodiment, the barrier layer of each multi-quantum well layer includes a Si-doped front GaN layer, an AlGaN layer not intentionally doped with Si, and a Si-doped back GaN layer stacked in sequence along the epitaxial direction.

[0187] The Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer decreases successively, and the total thickness of the single barrier layer decreases successively.

[0188] In this embodiment, the Al component contents of the AlGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are x1, x2, x3, and x4, respectively, where x1 is 0.03, x2 is 0.02, x3 is 0.01, and x4 is 0.005.

[0189] In this embodiment, the growth temperatures of the Si-doped front GaN layer and the Si-doped back GaN layer of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer increase successively, the Si doping concentration decreases successively, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer decreases successively, and the single layer thickness of each AlGaN layer that is not intentionally doped with Si is the same and the growth temperature is the same.

[0190] In this embodiment, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer in the first cyan multi-quantum well layer is 820°C, and the Si doping concentration is 4×10 17 / cm 3 In the second long-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 830°C, and the Si doping concentration is 3×10 17 / cm 3 In the third short-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 850°C, and the Si doping concentration is 2×10 17 / cm 3 In the fourth purple multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 880°C, and the Si doping concentration is 1×10 17 / cm 3 .

[0191] In this embodiment, in the first cyan multi-quantum well layer, the total thickness h1 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 10 nm; in the second long-wave blue multi-quantum well layer, the total thickness h2 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 8 nm; in the third short-wave blue multi-quantum well layer, the total thickness h3 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 6 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4 nm.

[0192] In this embodiment, the thickness of each AlGaN layer not intentionally doped with Si is 3 nm, and the growth temperature is 820°C.

[0193] In this embodiment, the well layers of each multi-quantum well layer include InGaN layers that are not intentionally doped with Si, and the In component content of the InGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth purple multi-quantum well layer decreases successively, and the growth temperature increases successively.

[0194] In this embodiment, the period number of the first cyan multi-quantum well layer is 1, the period number of the second long-wave blue multi-quantum well layer is 2, the period number of the third short-wave blue multi-quantum well layer is 2, and the period number of the fourth violet multi-quantum well layer is 1.

[0195] Furthermore, this embodiment provides a white light LED light source, including a fluorescent adhesive layer and the above-mentioned LED chip, wherein the fluorescent adhesive layer includes red fluorescent powder and green fluorescent powder.

[0196] Comparative Example 1

[0197] The difference between this comparative example and Example 1 is that, in this comparative example, the Al component content of the AlGaN layer that is not intentionally doped with Si remains consistent among the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth purple multi-quantum well layer, and is 0.15.

[0198] Comparative Example 2

[0199] The difference between this comparative example and Example 1 is that in this comparative example, the first cyan multi-quantum well layer is not provided, and the number of periods of the second long-wave blue multi-quantum well layer is 3.

[0200] Comparative Example 3

[0201] The difference between this comparative example and Example 1 is that in this comparative example, the second long-wave blue multi-quantum well layer is not provided, and the number of periods of the first cyan multi-quantum well layer is 3.

[0202] Comparative Example 4

[0203] The difference between this comparative example and Example 1 is that, in this comparative example, the third short-wave blue multi-quantum well layer is not provided, and the number of periods of the fourth purple multi-quantum well layer is 3.

[0204] Comparative Example 5

[0205] The difference between this comparative example and Example 1 is that, in this comparative example, the fourth purple multi-quantum well layer is not provided, and the number of periods of the third short-wave blue multi-quantum well layer is 3.

[0206] Comparative Example 6

[0207] The difference between this comparative example and Example 1 is that, in this comparative example, only the third short-wave blue light multi-quantum well layer is provided in the light-emitting layer, and the number of periods of the third short-wave blue light multi-quantum well layer is 6.

[0208] The electrical parameters of Examples 1 to 5 and Comparative Examples 1 to 6 were tested, and the luminous efficiency improvement rate of the remaining experimental groups relative to Comparative Example 6 was calculated. The color rendering performance of each experimental group was tested, and the test results are as follows:

[0209]

[0210] The experimental results show that compared with Comparative Examples 1 to 6, Examples 1 to 5 using the light-emitting layer structure design of the present invention have higher color rendering performance and luminous efficiency.

[0211] Among them, by comparing Example 1 with Comparative Examples 1 to Comparative Examples 6, it can be seen that the present invention adopts a light-emitting layer structure that combines a first cyan light multi-quantum well layer, a second long-wave blue light multi-quantum well layer, a third short-wave blue light multi-quantum well layer, and a fourth purple light multi-quantum well layer, which can form a spectrum that is more continuous, smoother, and closer to natural light, and effectively improve the color rendering performance of the white light source.

[0212] By comparing Examples 1 to 3, it can be seen that the emission wavelength of each multi-quantum well layer and the change in the bandgap width of the barrier layer will affect the color rendering performance and the luminous efficiency.

[0213] By comparing Example 1 and Example 4, it can be seen that the decreasing bandgap design of the barrier layers of each multi-quantum well layer from the first cyan multi-quantum well layer to the fourth purple multi-quantum well layer combined with the decreasing thickness design of the barrier layers of each multi-quantum well layer from the first cyan multi-quantum well layer to the fourth purple multi-quantum well layer is more conducive to improving the luminous efficiency.

[0214] By comparing Example 1 and Example 5 with Comparative Example 1, it can be seen that the decreasing setting of the emission wavelength of each multi-quantum well layer from the first cyan multi-quantum well layer to the fourth purple multi-quantum well layer combined with the decreasing setting of the barrier band gap width of each multi-quantum well layer from the first cyan multi-quantum well layer to the fourth purple multi-quantum well layer can effectively improve the luminescence efficiency.

[0215] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents suggested above. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the solution of the present invention.

Claims

1. A multi-band LED chip comprising a substrate and an epitaxial layer disposed on the substrate, characterized in that: The epitaxial layer includes a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer and a P-type layer arranged in sequence along the epitaxial direction; The light-emitting layer comprises a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer stacked in sequence along the epitaxial direction; The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers. The emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence. The bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence; The first cyan multi-quantum well layer has an emission wavelength of 492 nm, 495 nm, 498 nm or 500 nm, the second long-wave blue multi-quantum well layer has an emission wavelength of 460 nm to 480 nm, the third short-wave blue multi-quantum well layer has an emission wavelength of 445 nm to 460 nm, and the fourth violet multi-quantum well layer has an emission wavelength of 430 nm to 445 nm. Each of the barrier layers comprises a front Si-doped GaN layer, an AlGaN layer not intentionally doped with Si, and a back Si-doped GaN layer, which are sequentially stacked along the epitaxial direction. Moreover, the Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth purple multi-quantum well layer decreases successively, and the total thickness of the single barrier layer decreases successively.

2. The multi-band LED chip according to claim 1, characterized in that: The Al component contents of the AlGaN layers that are not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth purple multi-quantum well layer are x1, x2, x3 and x4, respectively, wherein 0.03≤x1≤0.15, 0.02≤x2≤0.12, 0.01≤x3≤0.1, and 0<x4≤0.

08.

3. The multi-band LED chip according to claim 1, characterized in that: The growth temperatures of the Si-doped front GaN layer and the Si-doped back GaN layer of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer and the fourth violet multi-quantum well layer increase successively, and the Si doping concentration decreases successively. The total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer decreases successively, and the single layer thickness of each AlGaN layer that is not intentionally doped with Si is the same and the growth temperature is the same.

4. The multi-band LED chip according to claim 3, characterized in that: In the first cyan multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 820°C to 913°C, and the Si doping concentration is 1.5×10 17 / cm 3 ~7.9×10 17 / cm 3 In the second long-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped back GaN layer is 825°C~918°C, and the Si doping concentration is 1.3×10 17 / cm 3 ~7.3×10 17 / cm 3 In the third short-wave blue multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 830°C~923°C, and the Si doping concentration is 1.1×10 17 / cm 3 ~6.7×10 17 / cm 3 In the fourth purple multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 835°C~928°C, and the Si doping concentration is 0.9×10 17 / cm 3 ~6.3×10 17 / cm 3 and / or, In the first cyan multi-quantum well layer, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 6 nm to 12 nm; in the second long-wave blue multi-quantum well layer, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 5.2 nm to 11.2 nm; in the third short-wave blue multi-quantum well layer, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4.6 nm to 10.6 nm; in the fourth violet multi-quantum well layer, the total thickness of the Si-doped front GaN layer and the Si-doped back GaN layer in a single barrier layer is 4 nm to 10 nm; and / or, The thickness of each AlGaN layer not intentionally doped with Si is 1 nm to 5 nm, and the growth temperature is 780° C. to 928° C.

5. The multi-band LED chip according to claim 1, characterized in that: Each of the well layers includes an InGaN layer that is not intentionally doped with Si, and the In component content of the InGaN layer that is not intentionally doped with Si in the first cyan light multi-quantum well layer, the second long-wave blue light multi-quantum well layer, the third short-wave blue light multi-quantum well layer and the fourth purple light multi-quantum well layer decreases successively, and the growth temperature increases successively.

6. A method for preparing a multi-band LED chip, characterized in that: include: providing a substrate; Depositing an epitaxial layer on the substrate, wherein the epitaxial layer includes a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer sequentially arranged along an epitaxial direction; The light-emitting layer comprises a first cyan multi-quantum well layer, a second long-wave blue multi-quantum well layer, a third short-wave blue multi-quantum well layer and a fourth violet multi-quantum well layer stacked in sequence along the epitaxial direction; The first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternating well layers and barrier layers. The emission wavelengths of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence. The bandgap widths of the barrier layers of the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence; The first cyan multi-quantum well layer has an emission wavelength of 492 nm, 495 nm, 498 nm or 500 nm, the second long-wave blue multi-quantum well layer has an emission wavelength of 460 nm to 480 nm, the third short-wave blue multi-quantum well layer has an emission wavelength of 445 nm to 460 nm, and the fourth violet multi-quantum well layer has an emission wavelength of 430 nm to 445 nm. Each of the barrier layers includes a front Si-doped GaN layer, an AlGaN layer not intentionally doped with Si, and a back Si-doped GaN layer stacked sequentially along the epitaxial direction, and the Al component content of the AlGaN layer not intentionally doped with Si in the first cyan multi-quantum well layer, the second long-wave blue multi-quantum well layer, the third short-wave blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases sequentially, and the total thickness of a single barrier layer decreases sequentially.

7. A white light LED light source, characterized in that: The invention comprises a fluorescent adhesive layer and the LED chip according to any one of claims 1 to 5, wherein the fluorescent adhesive layer comprises red phosphor and green phosphor.

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