Multiband LED chip and preparation method thereof, and white light LED light source

Abstract

The invention relates to the technical field of semiconductors, and particularly discloses a multiband LED chip and a preparation method thereof, and a white light LED light source, the LED chip comprises a light-emitting layer, and the light-emitting layer comprises 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 are sequentially stacked in the epitaxial direction; 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 are each of a periodic structure formed by alternately stacking well layers and barrier layers, and the light-emitting wavelengths of 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 are sequentially decreased. And the forbidden band widths of the barrier layers are sequentially decreased. According to the LED chip, the overall excitation efficiency can be effectively improved, and the output full-spectrum white light LED light source is higher in color rendering index, better in stability, less in damage to human eyes and high in light emitting efficiency.

Description

Technical Field

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

[0002] At present, the mainstream technical path of full-spectrum white LEDs is to use blue LED chips to excite a red and green mixed phosphor layer (including red phosphors and green phosphors), thereby realizing the output of full-spectrum white light. However, in the spectral curve of such full-spectrum white LED light sources, the spectral curve in the blue light band fluctuates greatly and has poor stability, which affects its luminous performance and use safety.

[0003] Analyzed from the perspective of the light-emitting mechanism, the instability of the blue light spectrum makes it difficult to achieve the best match between the blue light energy and the absorption and conversion efficiency of the phosphor during the process of exciting the phosphor to generate white light. It is difficult for the phosphor to be stably and fully excited by the blue light energy, and the emission intensities of green light and red light also fluctuate accordingly, resulting in a decrease in the overall luminous efficiency of the white LED and affecting the light output stability, resulting in a decrease in the color rendering index.

[0004] Analyzed from the perspective of health risks, the blue light hazard cannot be ignored. The instability of the spectral curve in the blue light band may cause stroboscopic problems that are difficult to detect by the naked eye. Long-term exposure to such a light source environment is likely to cause discomfort symptoms such as eye fatigue and dryness, and may even damage eyesight. And as early as 1966, Nell et al. found that blue light irradiation (especially in the short-wave blue light band) is likely to cause damage to retinal cells, and long-term exposure may lead to serious consequences such as vision loss. Summary of the Invention

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

[0006] The LED chip of the present invention can emit light of multiple different bands such as cyan light, long-wave blue light, short-wave blue light, and violet light. The light of multiple different bands acts synergistically, can more fully excite red phosphors and green phosphors, effectively improve the overall excitation efficiency, and 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.

[0007] To achieve the above object, the present invention adopts the following technical solutions: First, the present invention provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate. 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 the epitaxial direction; The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wavelength blue multi-quantum well layer, a third short-wavelength blue multi-quantum well layer, and a fourth violet multi-quantum well layer that are sequentially stacked along the epitaxial direction; The first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternately stacking well layers and barrier layers, The emission wavelengths of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, The band gaps of the barrier layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence.

[0008] In some embodiments, the emission wavelength of the first cyan multi-quantum well layer is 490 nm to 500 nm, the emission wavelength of the second long-wavelength blue multi-quantum well layer is 460 nm to 480 nm, the emission wavelength of the third short-wavelength blue multi-quantum well layer is 445 nm to 460 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430 nm to 445 nm.

[0009] In some embodiments, each of the barrier layers includes a Si-doped front GaN layer, an unintentionally Si-doped AlGaN layer, and a Si-doped rear GaN layer that are sequentially stacked along the epitaxial direction, and the Al component contents of the unintentionally Si-doped AlGaN layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, and the total thickness of a single barrier layer decreases in sequence.

[0010] In some embodiments, the Al component contents of the unintentionally Si-doped AlGaN layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer 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.

[0011] In some embodiments, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer increase in sequence, the Si doping concentrations decrease in sequence, the total thicknesses of the Si-doped front GaN layer and the Si-doped rear GaN layer within each barrier layer decrease in sequence, and the single-layer thicknesses of each unintentionally Si-doped AlGaN layer are the same, and the growth temperatures are the same.

[0012] In some embodiments, in the first cyan multi-quantum well layer, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer are 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-wavelength blue multi-quantum well layer, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer are 825 °C to 918 °C, and the Si doping concentration is 1.3×10 17 / cm 3 ~7.3×10 17 / cm 3 ; in the third short-wavelength blue multi-quantum well layer, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer are 830 °C to 923 °C, and the Si doping concentration is 1.1×10 17 / cm 3 ~6.7×10 17 / cm 3 ; in the fourth violet multi-quantum well layer, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer are 835 °C to 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 blue-green multi-quantum well layer, the total thickness of the Si-doped pre-GaN layer and the Si-doped post-GaN layer within a single barrier layer is 6 nm to 12 nm; in the second long-wavelength blue multi-quantum well layer, the total thickness of the Si-doped pre-GaN layer and the Si-doped post-GaN layer within a single barrier layer is 5.2 nm to 11.2 nm; in the third short-wavelength blue multi-quantum well layer, the total thickness of the Si-doped pre-GaN layer and the Si-doped post-GaN layer within 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 pre-GaN layer and the Si-doped post-GaN layer within a single barrier layer is 4 nm to 10 nm; and / or, The single-layer thickness of each of the unintentionally Si-doped AlGaN layers is 1 nm to 5 nm, and the growth temperature is 780 °C to 928 °C.

[0013] In some embodiments, each of the well layers includes an unintentionally Si-doped InGaN layer, and the In component content of the unintentionally Si-doped InGaN layers in the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases in sequence, and the growth temperature increases in sequence.

[0014] Secondly, the present invention provides a method for manufacturing a multi-band LED chip, including: Providing a substrate; Depositing an epitaxial layer on the substrate, the epitaxial layer including a buffer layer, an N-type layer, a light-emitting layer, an electron blocking layer, and a P-type layer sequentially arranged along the epitaxial direction; The light-emitting layer includes a first blue-green multi-quantum well layer, a second long-wavelength blue multi-quantum well layer, a third short-wavelength blue multi-quantum well layer, and a fourth violet multi-quantum well layer sequentially stacked along the epitaxial direction; The first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternately stacking well layers and barrier layers, The emission wavelengths of the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, The band gaps of the barrier layers of the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence.

[0015] In some embodiments, the emission wavelength of the first blue-green multi-quantum well layer is 490 nm to 500 nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 460 nm to 480 nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 445 nm to 460 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430 nm to 445 nm; and / or, Each of the barrier layers includes a Si-doped front GaN layer, an unintentionally Si-doped AlGaN layer, and a Si-doped rear GaN layer that are sequentially stacked along the epitaxial direction. The Al component content of the unintentionally Si-doped AlGaN layer of the first blue-green 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 in sequence, and the total thickness of a single barrier layer decreases in sequence.

[0016] Furthermore, the present invention provides a white LED light source, including a fluorescent glue layer and the above-mentioned LED chip, and the fluorescent glue layer includes a red phosphor and a green phosphor.

[0017] The beneficial effects of the present invention are as follows: First of all, compared with the existing technical solution that uses 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 lights of multiple different wavelength 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 blue-green 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 that are sequentially stacked along the epitaxial direction. The emission wavelength corresponding to each multi-quantum well layer decreases layer by layer from the first blue-green multi-quantum well layer to the fourth violet multi-quantum well layer, so that the LED chip can emit blue-green light, long-wave blue light, short-wave blue light, and violet light. The excitation light source spans from blue-green light to violet light, fully exciting the red phosphor and the green phosphor. The lights of different wavelength bands act synergistically to enhance the luminescence effect of the phosphor. When multiple wavelength lights act together, they can more comprehensively match the absorption spectrum of the phosphor. And because the emission wavelength corresponding to each multi-quantum well layer of the present invention decreases layer by layer from the first blue-green multi-quantum well layer to the fourth violet multi-quantum well layer, when the LED chip emits light along the epitaxial direction, the low-energy long-wave light emitted by the front 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, it makes up for the spectral gaps in exciting the red phosphor and the green phosphor. The red light, green light, and the excitation light that is not absorbed and directly transmitted by each wavelength light generated by the excitation can form a more continuous, smoother, and more natural light-like spectrum, effectively improving the color rendering index. And, the proportion of blue light (especially short-wave blue light) in the light source emitted by the LED chip is reduced, effectively improving the stroboscopic phenomenon and the damage to the human eye caused by the blue light spectrum fluctuation, which is beneficial to protecting eye health.

[0018] Secondly, while setting the emission wavelengths corresponding to the multiple quantum well layers in the light-emitting layer to decrease gradually from the first cyan multiple quantum well layer to the fourth violet multiple quantum well layer, the present invention also makes the band gaps of the barrier layers corresponding to the multiple quantum well layers decrease gradually 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 multiple quantum well layers decrease gradually from the first cyan multiple quantum well layer to the fourth violet multiple quantum well layer, correspondingly, the emission energy increases gradually from the first cyan multiple quantum well layer to the fourth violet multiple quantum well layer. The multiple quantum well layer closer to the P-type layer has higher energy, and the multiple quantum well layer closer to the N-type layer has lower energy. Since electrons have relatively high mobility, they are more likely to be injected into the multiple quantum well layer with higher energy under the action of an electric field. Moreover, this setting can form a better confinement of electrons by the multiple quantum well layer with high energy, reducing the probability of electron leakage to the P-type layer. At the same time, the accumulation of electrons in the multiple quantum well layer with high energy will generate an electric field, which has an attracting effect on holes, promoting more holes to be injected into the light-emitting layer. At the same time, since holes have relatively low mobility, the setting of the multiple quantum well layer with lower energy closer to the N-type layer is more conducive to the injection of holes into the multiple quantum well layer closer to the N-type layer. Thus, it promotes the carriers to be more effectively injected into each quantum well layer, improving the recombination efficiency of the carriers. On the other hand, since the emission wavelengths corresponding to the multiple quantum well layers decrease gradually from the first cyan multiple quantum well layer to the fourth violet multiple quantum well layer, the band gaps of the well layers increase gradually layer by layer. Combining with the setting that the band gaps of the barrier layers corresponding to the multiple quantum well layers decrease gradually layer by layer, the potential barriers corresponding to the multiple quantum well layers decrease in turn from the first cyan multiple quantum well layer to the fourth violet multiple quantum well layer. When high-mobility electrons are injected from the N-type layer into the light-emitting layer, the high-potential-barrier multiple quantum well layer closer to the N-type layer can increase the lateral transmission path of electrons, delaying the transmission rate of electrons and increasing the chance of electrons meeting and recombining with holes. Correspondingly, under the action of the electric field and the influence of its own characteristics, holes are more likely to be injected into the light-emitting layer and recombine with the confined electrons, improving the radiative recombination efficiency and enhancing the emission intensity. Thus, by making the emission wavelengths corresponding to the multiple quantum well layers and the band gaps of the corresponding barrier layers decrease in turn from the first cyan multiple quantum well layer to the fourth violet multiple quantum well layer, and the two acting synergistically, the carriers can be more effectively injected into each quantum well layer, thereby improving the recombination efficiency of holes and electrons, and effectively enhancing the emission efficiency.

[0019] Accordingly, in the light-emitting layer of the LED chip of the present invention, a first cyan multi-quantum well layer, a second long-wavelength blue multi-quantum well layer, a third short-wavelength blue multi-quantum well layer, and a fourth violet multi-quantum well layer are sequentially stacked along the epitaxial direction, and the emission wavelengths corresponding to each multi-quantum well layer and the bandgap widths of the corresponding barrier layers decrease sequentially from the first cyan multi-quantum well layer to the fourth violet multi-quantum well layer. The LED chip can emit lights of multiple different wavelength bands such as cyan light, long-wavelength blue light, short-wavelength blue light, and violet light. The lights of multiple different wavelength bands act synergistically, which can more fully excite the red phosphor and the green phosphor, effectively improve the overall excitation efficiency, the color rendering index of the output full-spectrum white LED light source is higher, the stability is better, the damage to the human eye is less, and the luminous efficiency is high. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of a multi-band LED chip according to an embodiment of the present invention.

[0021] Figure 2 It is a schematic structural diagram of the light-emitting layer of the LED chip according to an embodiment of the present invention.

[0022] Figure 3 It is a schematic structural diagram of a single period of the first cyan multi-quantum well layer according to an embodiment of the present invention.

[0023] Figure 4 It is a schematic structural diagram of a single period of the second long-wavelength blue multi-quantum well layer according to an embodiment of the present invention.

[0024] Figure 5 It is a schematic structural diagram of a single period of the third short-wavelength blue multi-quantum well layer according to an embodiment of the present invention.

[0025] Figure 6 It is a schematic structural diagram of a single period of the fourth violet multi-quantum well layer according to an embodiment of the present invention. Detailed Embodiments

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below.

[0027] First, referring to Figures 1 to 2 as shown, the present invention provides a multi-band LED chip, including a substrate 1 and an epitaxial layer disposed on the substrate 1. The epitaxial layer includes 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; The light-emitting layer 5 includes a first cyan multi-quantum well layer 51, a second long-wavelength blue multi-quantum well layer 52, a third short-wavelength blue multi-quantum well layer 53, and a fourth violet multi-quantum well layer 54 sequentially stacked along the epitaxial direction; The first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 are all periodic structures formed by alternately stacking well layers and barrier layers. The emission wavelengths of the first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decrease in sequence. The band gaps of the barrier layers of the first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decrease in sequence.

[0028] Among them, each multi-quantum well layer (the first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, the fourth violet multi-quantum well layer 54) is a periodic structure formed by alternately stacking 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 denoted as the first well layer 51A, and the barrier layer is denoted as the first barrier layer 51B; the well layer of the second long-wavelength blue multi-quantum well layer 52 is denoted as the second well layer 52A, and the barrier layer is denoted as the second barrier layer 52B; the well layer of the third short-wavelength blue multi-quantum well layer 53 is denoted as the third well layer 53A, and the barrier layer is denoted as the third barrier layer 53B; the well layer of the fourth violet multi-quantum well layer 54 is denoted as the fourth well layer 54A, and the barrier layer is denoted as the fourth barrier layer 54B.

[0029] In the present invention, between each of the first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54, the emission wavelengths decrease in sequence, and the band gaps of the barrier layers decrease in sequence. That is, the emission wavelength λ1 of the first cyan multi-quantum well layer 51, the emission wavelength λ2 of the second long-wavelength blue multi-quantum well layer 52, the emission wavelength λ3 of the third short-wavelength blue multi-quantum well layer 53, and the emission wavelength λ4 of the fourth violet multi-quantum well layer 54 decrease in sequence, λ1 > λ2 > λ3 > λ4; the band gap Eg1 of the first barrier layer 51B, the band gap Eg2 of the second barrier layer 52B, the band gap Eg3 of the third barrier layer 53B, and the band gap Eg4 of the fourth barrier layer 54B decrease in sequence, Eg1 > Eg2 > Eg3 > Eg4.

[0030] First, compared with the existing technical solutions that use 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 emit excitation lights of multiple different wavelength bands simultaneously 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 violet multi-quantum well layer 54 that are sequentially stacked along the epitaxial direction. The emission wavelengths corresponding to the respective 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, 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. The lights of different wavelength bands act synergistically to enhance the luminescence effect of the phosphor. When lights of multiple wavelengths act together, they can more comprehensively match the absorption spectrum of the phosphor. And because the emission wavelengths corresponding to the respective multi-quantum well layers of the present invention decrease layer by layer 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 front 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, it makes up for the spectral gaps in exciting the red phosphor and the green phosphor. The red light, green light, and the excitation light that is not absorbed and directly transmitted by the lights of each wavelength generated by the excitation can form a more continuous, smoother, and more natural light-like spectrum, effectively improving the color rendering index. And the proportion of blue light (especially short-wave blue light) in the light source emitted by the LED chip is reduced, effectively improving the stroboscopic phenomenon and the damage to the human eye caused by the blue light spectrum fluctuation, which is beneficial to protecting eye health.

[0031] Secondly, while setting the emission wavelengths of the respective multiple quantum well layers in the light-emitting layer 5 to decrease gradually from the first cyan multiple quantum well layer 51 to the fourth violet multiple quantum well layer 54, the present invention also makes the band gaps of the barrier layers corresponding to the respective multiple quantum well layers decrease gradually. 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 of the respective multiple quantum well layers decrease gradually from the first cyan multiple quantum well layer 51 to the fourth violet multiple quantum well layer 54, correspondingly, the emission energy increases gradually from the first cyan multiple quantum well layer 51 to the fourth violet multiple quantum well layer 54. The multiple quantum well layer closer to the P-type layer 7 has a higher energy, and the multiple quantum well layer closer to the N-type layer 3 has a lower energy. Since electrons have a relatively high mobility, they are more likely to be injected into the multiple quantum well layer with a higher energy under the action of an electric field. Moreover, this setting can form a better confinement of electrons by the multiple quantum well layer with a higher energy, reducing the probability of electrons leaking into the P-type layer 7. At the same time, the accumulation of electrons in the multiple quantum well layer with a higher energy will generate an electric field, which has an attracting effect on holes, promoting more holes to be injected into the light-emitting layer 5. At the same time, since holes have a relatively low mobility, the setting of the multiple quantum well layer with a lower energy closer to the N-type layer 3 is more conducive to the injection of holes into the multiple quantum well layer closer to the N-type layer 3. Thus, it is promoted that carriers can be more effectively injected into each quantum well layer, improving the recombination efficiency of carriers. On the other hand, since the emission wavelengths of the respective multiple quantum well layers decrease gradually from the first cyan multiple quantum well layer 51 to the fourth violet multiple quantum well layer 54, the band gaps of the well layers increase gradually. Combining with the setting that the band gaps of the barrier layers corresponding to the respective multiple quantum well layers decrease gradually, the potential barriers corresponding to the respective multiple quantum well layers decrease in turn from the first cyan multiple quantum well layer 51 to the fourth violet multiple quantum well layer 54. When the high-mobility electrons are injected from the N-type layer 3 into the light-emitting layer 5, the high-potential-barrier multiple quantum well layer closer to the N-type layer 3 can increase the lateral transmission path of electrons, delaying the transmission rate of electrons and increasing the chance of electrons meeting and recombining with holes. Correspondingly, under the action of an electric field and the influence of its own characteristics, holes are more likely to be injected into the light-emitting layer 5 and recombine with the confined electrons, improving the radiative recombination efficiency and enhancing the emission intensity. Thus, by making the emission wavelengths and the band gaps of the corresponding barrier layers of the respective multiple quantum well layers decrease in turn from the first cyan multiple quantum well layer 51 to the fourth violet multiple quantum well layer 54, and the two acting synergistically, carriers can be more effectively injected into each quantum well layer, thereby improving the recombination efficiency of holes and electrons, and effectively enhancing the emission efficiency.

[0032] Accordingly, in the light-emitting layer 5 of the LED chip of the present invention, a first cyan multi-quantum well layer 51, a second long-wavelength blue multi-quantum well layer 52, a third short-wavelength blue multi-quantum well layer 53, and a fourth violet multi-quantum well layer 54 are sequentially stacked along the epitaxial direction, and the emission wavelengths of the respective multi-quantum well layers and the bandgap widths of the corresponding barrier layers decrease sequentially from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54. The LED chip can emit lights of multiple different wavelength bands such as cyan light, long-wavelength blue light, short-wavelength blue light, and violet light. The lights of multiple different wavelength bands act synergistically, can more fully excite the red phosphor and the green phosphor, effectively improve the overall excitation efficiency, the color rendering index of the output full-spectrum white LED light source is higher, the stability is better, the damage to the human eye is less, and the luminous efficiency is high.

[0033] In some embodiments, the emission wavelength of the first cyan multi-quantum well layer 51 is 490 nm to 500 nm, the emission wavelength of the second long-wavelength blue multi-quantum well layer 52 is 460 nm to 480 nm, the emission wavelength of the third short-wavelength blue multi-quantum well layer 53 is 445 nm to 460 nm, and the emission wavelength of the fourth violet multi-quantum well layer 54 is 430 nm to 445 nm.

[0034] By regulating the emission wavelengths of the respective multi-quantum well layers in the light-emitting layer 5, the lights of different wavelength bands act synergistically to fully excite the red phosphor and the green phosphor, can more comprehensively match the absorption spectrum of the phosphor. At the same time, the spectral gaps when exciting the red phosphor and the green phosphor are compensated for each other. The red light, green light, and the excitation light that is not absorbed and directly transmitted at each wavelength generated by the excitation can form a more continuous, smoother, and more natural light-like spectrum, effectively improving the color rendering index. Moreover, the proportion of blue light (especially short-wavelength blue light) in the light source emitted by the LED chip is reduced, effectively improving the stroboscopic phenomenon and the damage to the human eye caused by the blue light spectrum fluctuation, which is beneficial to protecting eye health.

[0035] Exemplarily, the 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.

[0036] Exemplarily, the emission wavelength λ2 of the second long-wavelength 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.

[0037] Exemplarily, the emission wavelength λ3 of the third short-wavelength 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.

[0038] Exemplarily, the emission wavelength λ4 of the fourth violet multi-quantum well layer 54 is 430 nm, 432 nm, 435 nm, 438 nm, 440 nm, 442 nm or 445 nm, but not limited thereto.

[0039] It can be understood that there is an overlapping region in the value ranges of the emission wavelengths corresponding to the above-mentioned respective multi-quantum well layers. During fabrication, it is only necessary to ensure that the emission wavelengths decrease sequentially among the four multi-quantum well layers from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54.

[0040] In some embodiments, referring to 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 undoped Si AlGaN layer, and a Si-doped rear GaN layer that are sequentially stacked along the epitaxial direction. Moreover, the Al composition content of the undoped Si AlGaN layer of the first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decreases sequentially, and the total thickness of a single barrier layer decreases sequentially.

[0041] By making the Al composition content of the undoped Si AlGaN layer corresponding to each multi-quantum well layer decrease layer by layer from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54, and making the total thickness of the barrier layer corresponding to each multi-quantum well layer decrease sequentially, 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. Among them, the lower barrier height makes it easier for holes to be injected into the light-emitting layer 5. At the same time, the thin barrier structure can shorten the distance for holes to cross the barrier layer, further reducing the crossing difficulty and increasing the hole concentration in the light-emitting layer 5. As a result, there are also sufficient holes in the multi-quantum well layer close to the N-type layer 3 to participate in 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. Among them, the higher barrier height can effectively increase the lateral transport path of electrons, delay the electron transport rate, increase the chance of electrons meeting and recombining with holes, and can effectively prevent electron overflow. Thus, through the combination of the thin barrier structure with a low barrier height and the thick barrier structure with a high barrier height, the two work together, enabling carriers to be more effectively injected into each quantum well layer, thereby increasing the recombination efficiency of holes and electrons, and effectively improving the light-emitting efficiency.

[0042] Among them, referring to Figures 3 to 6As shown in the figure, for the convenience of the following description, the Si-doped pre-GaN layer of the first barrier layer 51B is denoted as the first pre-GaN layer 511, the AlGaN layer without intentional Si doping is denoted as the first AlGaN layer 512, and the Si-doped post-GaN layer is denoted as the first post-GaN layer 513; the Si-doped pre-GaN layer of the second barrier layer 52B is denoted as the second pre-GaN layer 521, the AlGaN layer without intentional Si doping is denoted as the second AlGaN layer 522, and the Si-doped post-GaN layer is denoted as the second post-GaN layer 523; the Si-doped pre-GaN layer of the third barrier layer 53B is denoted as the third pre-GaN layer 531, the AlGaN layer without intentional Si doping is denoted as the third AlGaN layer 532, and the Si-doped post-GaN layer is denoted as the third post-GaN layer 533; the Si-doped pre-GaN layer of the fourth barrier layer 54B is denoted as the fourth pre-GaN layer 541, the AlGaN layer without intentional Si doping is denoted as the fourth AlGaN layer 542, and the Si-doped post-GaN layer is denoted as the fourth post-GaN layer 543.

[0043] In the present invention, the Al composition content of the AlGaN layers without intentional Si doping in the first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decreases in sequence, and the total thickness of a single barrier layer decreases in sequence, that is: The Al composition content x1 of the first AlGaN layer 512, the Al composition x2 of the second AlGaN layer 522, the Al composition x3 of the third AlGaN layer 532, and the Al composition x4 of the fourth AlGaN layer 542 decrease in sequence, and x1 > x2 > x3 > x4; The total thickness H1 of a single first barrier layer 51B, the total thickness H2 of a single second barrier layer 52B, the total thickness H3 of a single third barrier layer 53B, and the total thickness H4 of a single fourth barrier layer 54B decrease in sequence, and H1 > H2 > H3 > H4.

[0044] In some embodiments, the Al composition contents of the AlGaN layers without intentional Si doping in the first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength 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.

[0045] By adjusting the Al composition content in each multi-quantum well layer, a decreasing trend is formed layer by layer from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54 between the barrier layers of each multi-quantum well layer. The content of the Al component should not be too high, otherwise it is easy to increase the defects of the material layer. The content of the Al component should not be too low, otherwise it is difficult to form a sufficient barrier height.

[0046] Exemplarily, 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 not limited thereto.

[0047] Exemplarily, 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 not limited thereto.

[0048] Exemplarily, x3 is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09 or 0.1, but not limited thereto.

[0049] Exemplarily, x4 is 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07 or 0.08, but not limited thereto.

[0050] It can be understood that there is an overlapping region in the value ranges of the above x1, x2, x3 and x4. During preparation, it is only necessary to ensure that the Al component content of the AlGaN layers without intentional Si doping corresponding to the four multiple quantum well layers from the first blue-green multiple quantum well layer 51 to the fourth violet multiple quantum well layer 54 decreases sequentially.

[0051] In some embodiments, the growth temperatures of the Si-doped pre-GaN layers and the Si-doped post-GaN layers of the first blue-green multiple quantum well layer 51, the second long-wavelength blue light multiple quantum well layer 52, the third short-wavelength blue light multiple quantum well layer 53 and the fourth violet multiple quantum well layer 54 increase sequentially, the Si doping concentrations decrease sequentially, the total thicknesses of the Si-doped pre-GaN layers and the Si-doped post-GaN layers within a single barrier layer decrease sequentially, and the single-layer thicknesses and growth temperatures of the AlGaN layers without intentional Si doping are the same, that is: The growth temperatures T1 of the first pre-GaN layer 511 and the first post-GaN layer 513, the growth temperatures T2 of the second pre-GaN layer 521 and the second post-GaN layer 523, the growth temperatures T3 of the third pre-GaN layer 531 and the third post-GaN layer 533, and the growth temperatures T4 of the fourth pre-GaN layer 541 and the fourth post-GaN layer 543 show an increasing trend in sequence, T1 < T2 < T3 < T4; The Si doping concentrations N1 of the first pre-GaN layer 511 and the first post-GaN layer 513, the Si doping concentrations N2 of the second pre-GaN layer 521 and the second post-GaN layer 523, the Si doping concentrations N3 of the third pre-GaN layer 531 and the third post-GaN layer 533, and the Si doping concentrations N4 of the fourth pre-GaN layer 541 and the fourth post-GaN layer 543 show a decreasing trend in sequence, N1 > N2 > N3 > N4; The total thickness h1 of the first front GaN layer 511 and the first rear GaN layer 513 in a single first barrier layer 51B, the total thickness h2 of the second front GaN layer 521 and the second rear GaN layer 523 in a single second barrier layer 52B, the total thickness h3 of the third front GaN layer 531 and the third rear GaN layer 533 in a single third barrier layer 53B, and the total thickness h4 of the fourth front GaN layer 541 and the fourth rear GaN layer 543 in a single fourth barrier layer 54B show a decreasing trend in sequence, h1 > h2 > h3 > h4; The single-layer thicknesses of the first AlGaN layer 512, the second AlGaN layer 522, the third AlGaN layer 532, and the fourth AlGaN layer 542 are the same, and the growth temperatures are also the same.

[0052] Among them, when each multi-quantum well layer uses an InGaN layer as the well layer, since the emission wavelengths corresponding to each multi-quantum well layer decrease in sequence from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54, the content of In component in the well layer of each multi-quantum well layer correspondingly shows a decreasing change. The growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer corresponding to each multi-quantum well layer increase in sequence from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54, which can ensure the smooth incorporation of In component in the well layer of each multi-quantum well layer while improving the overall quality of the light-emitting layer 5, being beneficial to improving the light-emitting efficiency and light-emitting stability. The Si doping concentrations of the Si-doped front GaN layer and the Si-doped rear GaN layer corresponding to each multi-quantum well layer decrease in sequence from the first cyan multi-quantum well layer 51 to the fourth violet multi-quantum well layer 54. Each multi-quantum well layer can supplement an appropriate amount of electrons, optimize the distribution of carriers in the entire multi-band light-emitting structure, and improve the light-emitting efficiency of each band. At the same time, the lower Si doping concentration can reduce the lattice distortion caused by too high Si doping concentration, cooperate with the above-mentioned increasing setting of growth temperature, improve the overall quality of the light-emitting layer 5, and be beneficial to further improving the light-emitting efficiency and light-emitting stability.

[0053] In some embodiments, in the first cyan multi-quantum well layer 51, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer are 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 52, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer are 825 °C to 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 light multi-quantum well layer 53, the growth temperature of the pre-doped Si GaN layer and the post-doped Si GaN layer is 830°C to 923°C, and the Si doping concentration is 1.1×10 17 / cm 3 ~6.7×10 17 / cm 3 ; In the fourth violet light multi-quantum well layer 54, the growth temperature of the pre-doped Si GaN layer and the post-doped Si GaN layer is 835°C to 928°C, and the Si doping concentration is 0.9×10 17 / cm 3 ~6.3×10 17 / cm 3 。

[0054] In each multi-quantum well layer, the Si doping concentration in the pre-doped Si GaN layer and the post-doped Si GaN layer should not be too high (especially in the pre-doped Si GaN layer and the post-doped Si GaN layer in the fourth violet light multi-quantum well layer 54), otherwise it is easy to cause excessive electron injection, and it is easy to increase the risk of electron-hole recombination imbalance and the risk of electron overflow.

[0055] Exemplarily, the growth temperature T1 of the first pre-GaN layer 511 and the first post-GaN layer 513 can 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 not limited thereto.

[0056] Exemplarily, the growth temperature T2 of the second pre-GaN layer 521 and the second post-GaN layer 523 can 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 not limited thereto.

[0057] Exemplarily, the growth temperature T3 of the third pre-GaN layer 531 and the third post-GaN layer 533 can 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 not limited thereto.

[0058] Exemplarily, the growth temperature T4 of the fourth front GaN layer 541 and the fourth back GaN layer 543 can 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.

[0059] Exemplarily, the Si doping concentration N1 of the first front GaN layer 511 and the first back GaN layer 513 can 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 / 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 、7.0×1017 / 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.

[0060] 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.

[0061] Exemplarily, the Si doping concentration N3 of the third front GaN layer 531 and the third back GaN layer 533 can 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 , 5.0×10 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 / cm3 , 6.2×10 17 / cm 3 , 6.5×10 17 / cm 3 or 6.7×10 17 / cm 3 , but not limited to this.

[0062] Exemplarily, the Si doping concentration N4 of the fourth front GaN layer 541 and the fourth rear GaN layer 543 can 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 thereto.

[0063] In some embodiments, in the first blue-green multi-quantum well layer 51, the total thickness h1 of the Si-doped pre-GaN layer and the Si-doped post-GaN layer in a single barrier layer is 6 nm to 12 nm; in the second long-wavelength blue light multi-quantum well layer 52, the total thickness h2 of the Si-doped pre-GaN layer and the Si-doped post-GaN layer in a single barrier layer is 5.2 nm to 11.2 nm; in the third short-wavelength blue light multi-quantum well layer 53, the total thickness h3 of the Si-doped pre-GaN layer and the Si-doped post-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 pre-GaN layer and the Si-doped post-GaN layer in a single barrier layer is 4 nm to 10 nm.

[0064] Exemplarily, the total thickness h1 of the first pre-GaN layer 511 and the first post-GaN layer 513 in a single first barrier layer 51B is 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, 10.5 nm, 10.8 nm, 11 nm, 11.2 nm, 11.5 nm, 11.8 nm or 12 nm, but not limited thereto.

[0065] Exemplarily, the total thickness h2 of the second pre-GaN layer 521 and the second post-GaN layer 523 in a single second barrier layer 52B is 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, 10.5 nm, 10.8 nm, 11 nm or 11.2 nm, but not limited thereto.

[0066] Exemplarily, the total thickness h3 of the third pre-GaN layer 531 and the third post-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 not limited thereto.

[0067] Exemplarily, the total thickness h4 of the fourth front GaN layer 541 and the fourth rear GaN layer 543 in a single fourth barrier layer 54B is 4 nm, 4.2 nm, 4.5 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 or 10 nm, but not limited thereto.

[0068] In some embodiments, within each multiple quantum well layer, the thickness of the Si-doped front GaN layer in a single barrier layer is the same as that of the Si-doped rear GaN layer.

[0069] In some embodiments, the single-layer thickness of each unintentionally Si-doped AlGaN layer is 1 nm to 5 nm, and the growth temperature is 780 °C to 928 °C.

[0070] Exemplarily, the single-layer thickness of each unintentionally Si-doped AlGaN layer (the first AlGaN layer 512, the second AlGaN layer 522, the third AlGaN layer 532, 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 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 not limited thereto.

[0071] In some embodiments, each well layer includes an unintentionally Si-doped InGaN layer, and the In component content of the unintentionally Si-doped InGaN layers in the first blue-green multiple quantum well layer 51, the second long-wavelength blue-light multiple quantum well layer 52, the third short-wavelength blue-light multiple quantum well layer 53, and the fourth violet multiple quantum well layer 54 decreases in sequence, and the growth temperature increases in sequence. By adjusting the In component in the corresponding well layers of each multiple quantum well layer, the emission wavelength is adjusted, and the growth temperature is set to increase in sequence, which is beneficial to improving the overall quality of the light-emitting layer 5 while ensuring the stability of the In component and further improving the light-emitting efficiency.

[0072] In some embodiments, in the first blue-green multi-quantum well layer 51, the In composition content of the InGaN layer without intentional Si doping is 0.19 to 0.21; in the second long-wavelength blue multi-quantum well layer 52, the In composition content of the InGaN layer without intentional Si doping is 0.16 to 0.19; in the third short-wavelength blue multi-quantum well layer 53, the In composition content of the InGaN layer without intentional Si doping is 0.13 to 0.16; in the fourth violet multi-quantum well layer 54, the In composition content of the InGaN layer without intentional Si doping is 0.1 to 0.13.

[0073] In some embodiments, as shown in Figure 1 a low-temperature stress release layer 4 may also be provided between the N-type layer 3 and the light-emitting layer 5.

[0074] In some embodiments, the number of periods of the first blue-green multi-quantum well layer 51 is 1 to 3, the number of periods of the second long-wavelength blue multi-quantum well layer 52 is 2 to 5, the number of periods of the third short-wavelength blue multi-quantum well layer 53 is 2 to 5, and the number of periods of the fourth violet multi-quantum well layer 54 is 1 to 3.

[0075] Secondly, as shown in Figure 1 and Figure 2 the present invention provides a method for preparing a multi-band LED chip, including: S100. Provide a substrate 1; S200. Deposit an epitaxial layer on the substrate 1, and the epitaxial layer includes 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; The light-emitting layer 5 includes a first blue-green multi-quantum well layer 51, a second long-wavelength blue multi-quantum well layer 52, a third short-wavelength blue multi-quantum well layer 53, and a fourth violet multi-quantum well layer 54 sequentially stacked along the epitaxial direction; The first blue-green multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength 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, the emission wavelengths of the first blue-green multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decrease in sequence, and the band gaps of the barrier layers of the first blue-green multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decrease in sequence.

[0076] In some embodiments, the emission wavelength of the first cyan multi-quantum well layer 51 is 490 nm to 500 nm, the emission wavelength of the second long-wavelength blue multi-quantum well layer 52 is 460 nm to 480 nm, the emission wavelength of the third short-wavelength blue multi-quantum well layer 53 is 445 nm to 460 nm, and the emission wavelength of the fourth violet multi-quantum well layer 54 is 430 nm to 445 nm.

[0077] In some embodiments, each barrier layer includes a Si-doped front GaN layer, an undoped Si AlGaN layer, and a Si-doped rear GaN layer that are sequentially stacked along the epitaxial direction. Moreover, the Al component content of the undoped Si AlGaN layer in the first cyan multi-quantum well layer 51, the second long-wavelength blue multi-quantum well layer 52, the third short-wavelength blue multi-quantum well layer 53, and the fourth violet multi-quantum well layer 54 decreases in sequence, and the total thickness of the barrier layer decreases in sequence.

[0078] Furthermore, the present invention provides a white LED light source, including a fluorescent glue layer and the above-mentioned LED chip, and the fluorescent glue layer includes a red phosphor and a green phosphor.

[0079] 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.

[0080] Exemplarily, the red phosphor can be at least one of a nitride red phosphor, a oxynitride red phosphor, or a fluoride red phosphor. For example, CaAlSiN3:Eu 2+ 、Sr2Si5N8:Eu 2+ 、K2SiF6:Mn 4+ 。

[0081] Exemplarily, the green phosphor can be at least one of a silicate green phosphor, a oxynitride green phosphor, or a garnet structure green phosphor. For example, β-SiAlON:Eu 2+ 、Lu3Al5O 12 :Ce 3+ 。

[0082] The LED chip of the present invention can emit lights of multiple different bands such as cyan light, long-wavelength blue light, short-wavelength blue light, and violet light. The lights of multiple different bands act synergistically, can more fully excite the red phosphor and the green phosphor, effectively improve the overall excitation efficiency, the color rendering index of the output full-spectrum white LED light source is higher, the stability is better, the damage to the human eye is less, and the luminous efficiency is high.

[0083] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Embodiment 1 First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate. 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 the epitaxial direction; 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; 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, and the band gaps 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.

[0084] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 490 nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 460 nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 445 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430 nm.

[0085] In this embodiment, the barrier layer of each multi-quantum well layer includes a pre-GaN layer doped with Si, an undoped AlGaN layer, and a post-GaN layer doped with Si sequentially stacked along the epitaxial direction. Moreover, the Al component content of the undoped AlGaN 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 decreases in sequence, and the total thickness of a single barrier layer decreases in sequence.

[0086] In this embodiment, the Al component contents of the undoped AlGaN 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 are x1, x2, x3, and x4 in sequence, where x1 is 0.15, x2 is 0.12, x3 is 0.1, and x4 is 0.08.

[0087] In this embodiment, the growth temperatures of the pre-GaN layer doped with Si and the post-GaN layer doped with Si 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 in sequence, the Si doping concentrations decrease in sequence, the total thicknesses of the pre-GaN layer doped with Si and the post-GaN layer doped with Si in a single barrier layer decrease in sequence, and the single-layer thicknesses and growth temperatures of the undoped AlGaN layers are the same.

[0088] In this embodiment, in the first blue-green multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 820 °C, and the Si doping concentration is 4×10 17 / cm 3 ; in the second long-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 830 °C, and the Si doping concentration is 3×10 17 / cm 3 ; in the third short-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 850 °C, and the Si doping concentration is 2×10 17 / cm 3 ; in the fourth violet multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 880 °C, and the Si doping concentration is 1×10 17 / cm 3 .

[0089] In this embodiment, in the first blue-green multi-quantum well layer, the total thickness h1 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 10 nm; in the second long-wavelength blue multi-quantum well layer, the total thickness h2 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 8 nm; in the third short-wavelength blue multi-quantum well layer, the total thickness h3 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 6 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 4 nm.

[0090] In this embodiment, the single-layer thickness of each unintentionally Si-doped AlGaN layer is 3 nm, and the growth temperature is 820 °C.

[0091] In this embodiment, the well layers of each multi-quantum well layer include unintentionally Si-doped InGaN layers, and the In component content of the unintentionally Si-doped InGaN layers in the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases in sequence, and the growth temperature increases in sequence.

[0092] In this embodiment, the number of periods of the first blue-green multi-quantum well layer is 1, the number of periods of the second long-wavelength blue multi-quantum well layer is 2, the number of periods of the third short-wavelength blue multi-quantum well layer is 2, and the number of periods of the fourth violet multi-quantum well layer is 1.

[0093] Furthermore, this embodiment provides a white LED light source, including a fluorescent glue layer and the above-mentioned LED chip, and the fluorescent glue layer includes red phosphor and green phosphor.

[0094] Embodiment 2 First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate. 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 the epitaxial direction; The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wavelength blue multi-quantum well layer, a third short-wavelength blue multi-quantum well layer, and a fourth violet multi-quantum well layer sequentially stacked along the epitaxial direction; The first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength 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-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, and the band gaps of the barrier layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence.

[0095] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 500 nm, the emission wavelength of the second long-wavelength blue multi-quantum well layer is 480 nm, the emission wavelength of the third short-wavelength blue multi-quantum well layer is 460 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 445 nm.

[0096] In this embodiment, the barrier layer of each multi-quantum well layer includes a Si-doped front GaN layer, an unintentionally Si-doped AlGaN layer, and a Si-doped rear GaN layer sequentially stacked along the epitaxial direction. Moreover, the Al component contents of the unintentionally Si-doped AlGaN layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, and the total thickness of a single barrier layer decreases in sequence.

[0097] In this embodiment, the Al component contents of the unintentionally Si-doped AlGaN layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength 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.

[0098] In this embodiment, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer increase in sequence, the Si doping concentrations decrease in sequence, the total thicknesses of the Si-doped front GaN layer and the Si-doped rear GaN layer in a single barrier layer decrease in sequence, and the single-layer thicknesses and growth temperatures of each unintentionally Si-doped AlGaN layer are the same.

[0099] In this embodiment, in the first blue-green multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 820 °C, and the Si doping concentration is 4×10 17 / cm 3 ; in the second long-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 830 °C, and the Si doping concentration is 3×10 17 / cm 3 ; in the third short-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 850 °C, and the Si doping concentration is 2×10 17 / cm 3 ; in the fourth violet multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 880 °C, and the Si doping concentration is 1×10 17 / cm 3 .

[0100] In this embodiment, in the first blue-green multi-quantum well layer, the total thickness h1 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer in a single barrier layer is 10 nm; in the second long-wavelength blue multi-quantum well layer, the total thickness h2 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer in a single barrier layer is 8 nm; in the third short-wavelength blue multi-quantum well layer, the total thickness h3 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer in a single barrier layer is 6 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer in a single barrier layer is 4 nm.

[0101] In this embodiment, the single-layer thickness of each unintentionally Si-doped AlGaN layer is 3 nm, and the growth temperature is 820 °C.

[0102] In this embodiment, the well layers of each multi-quantum well layer include unintentionally Si-doped InGaN layers, and the In component content of the unintentionally Si-doped InGaN layers in the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases in turn, and the growth temperature increases in turn.

[0103] In this embodiment, the number of periods of the first blue-green multi-quantum well layer is 1, the number of periods of the second long-wavelength blue multi-quantum well layer is 2, the number of periods of the third short-wavelength blue multi-quantum well layer is 2, and the number of periods of the fourth violet multi-quantum well layer is 1.

[0104] Furthermore, this embodiment provides a white LED light source, including a fluorescent glue layer and the above-mentioned LED chip, and the fluorescent glue layer includes red phosphor and green phosphor.

[0105] Embodiment 3 First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate. 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 the epitaxial direction; 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; 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. Moreover, 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 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.

[0106] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 495 nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 470 nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 450 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 440 nm.

[0107] In this embodiment, the barrier layer of each multi-quantum well layer includes a pre-GaN layer doped with Si, an undoped AlGaN layer, and a post-GaN layer doped with Si sequentially stacked along the epitaxial direction, and the Al component content of the undoped AlGaN 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 decreases in sequence, and the total thickness of a single barrier layer decreases in sequence.

[0108] In this embodiment, the Al component contents of the undoped AlGaN 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 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.

[0109] In this embodiment, the growth temperatures of the pre-GaN layer doped with Si and the post-GaN layer doped with Si 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 in sequence, the Si doping concentrations decrease in sequence, the total thicknesses of the pre-GaN layer doped with Si and the post-GaN layer doped with Si in a single barrier layer decrease in sequence, and the single-layer thicknesses and growth temperatures of the undoped AlGaN layers are the same.

[0110] In this embodiment, in the first blue-green multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 820 °C, and the Si doping concentration is 4×10 17 / cm 3 ; in the second long-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 830 °C, and the Si doping concentration is 3×10 17 / cm 3 ; in the third short-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 850 °C, and the Si doping concentration is 2×10 17 / cm 3 ; in the fourth violet multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 880 °C, and the Si doping concentration is 1×10 17 / cm 3 .

[0111] In this embodiment, in the first blue-green multi-quantum well layer, the total thickness h1 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer in a single barrier layer is 10 nm; in the second long-wavelength blue multi-quantum well layer, the total thickness h2 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer in a single barrier layer is 8 nm; in the third short-wavelength blue multi-quantum well layer, the total thickness h3 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer in a single barrier layer is 6 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer in a single barrier layer is 4 nm.

[0112] In this embodiment, the single-layer thickness of each unintentionally Si-doped AlGaN layer is 3 nm, and the growth temperature is 820 °C.

[0113] In this embodiment, the well layers of each multi-quantum well layer include unintentionally Si-doped InGaN layers, and the In component content of the unintentionally Si-doped InGaN layers in the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases in sequence, and the growth temperature increases in sequence.

[0114] In this embodiment, the number of periods of the first blue-green multi-quantum well layer is 1, the number of periods of the second long-wavelength blue multi-quantum well layer is 2, the number of periods of the third short-wavelength blue multi-quantum well layer is 2, and the number of periods of the fourth violet multi-quantum well layer is 1.

[0115] Furthermore, this embodiment provides a white LED light source, including a fluorescent glue layer and the above-mentioned LED chip, and the fluorescent glue layer includes red phosphor and green phosphor.

[0116] Embodiment 4 First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate. 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 the epitaxial direction; 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; 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 alternately stacking 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, and the band gaps 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.

[0117] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 490 nm, the emission wavelength of the second long-wave blue multi-quantum well layer is 460 nm, the emission wavelength of the third short-wave blue multi-quantum well layer is 445 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430 nm.

[0118] In this embodiment, the barrier layer of each multi-quantum well layer includes a pre-GaN layer doped with Si, an AlGaN layer not intentionally doped with Si, and a post-GaN layer doped with Si sequentially stacked along the epitaxial direction, and the Al component contents of the AlGaN layers 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 decrease in sequence, and the total thickness of a single barrier layer decreases in sequence.

[0119] In this embodiment, the Al component contents of the AlGaN layers 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.

[0120] In this embodiment, the growth temperatures of the pre-GaN layer doped with Si and the post-GaN layer 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 increase in sequence, the Si doping concentrations decrease in sequence, the total thicknesses of the pre-GaN layer doped with Si and the post-GaN layer doped with Si in a single barrier layer decrease in sequence, and the single-layer thicknesses and growth temperatures of the AlGaN layers not intentionally doped with Si are the same.

[0121] In this embodiment, in the first blue-green multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 820 °C, and the Si doping concentration is 4×10 17 / cm 3 ; in the second long-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 830 °C, and the Si doping concentration is 3×10 17 / cm 3 ; in the third short-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 850 °C, and the Si doping concentration is 2×10 17 / cm 3 ; in the fourth violet multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 880 °C, and the Si doping concentration is 1×10 17 / cm 3 .

[0122] In this embodiment, in the first blue-green multi-quantum well layer, the total thickness h1 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 10 nm; in the second long-wavelength blue multi-quantum well layer, the total thickness h2 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 10 nm; in the third short-wavelength blue multi-quantum well layer, the total thickness h3 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 10 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 10 nm.

[0123] In this embodiment, the single-layer thickness of each unintentionally Si-doped AlGaN layer is 3 nm, and the growth temperature is 820 °C.

[0124] In this embodiment, the well layers of each multi-quantum well layer include unintentionally Si-doped InGaN layers, and the In component content of the unintentionally Si-doped InGaN layers in the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases in sequence, and the growth temperature increases in sequence.

[0125] In this embodiment, the number of periods of the first blue-green multi-quantum well layer is 1, the number of periods of the second long-wavelength blue multi-quantum well layer is 2, the number of periods of the third short-wavelength blue multi-quantum well layer is 2, and the number of periods of the fourth violet multi-quantum well layer is 1.

[0126] Furthermore, this embodiment provides a white LED light source, including a fluorescent glue layer and the above-mentioned LED chip, and the fluorescent glue layer includes red phosphor and green phosphor.

[0127] Embodiment 5 First, this embodiment provides a multi-band LED chip, including a substrate and an epitaxial layer disposed on the substrate. 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 the epitaxial direction; The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wavelength blue multi-quantum well layer, a third short-wavelength blue multi-quantum well layer, and a fourth violet multi-quantum well layer sequentially stacked along the epitaxial direction; The first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternately stacking well layers and barrier layers, The emission wavelengths of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, and the band gaps of the barrier layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence.

[0128] In this embodiment, the emission wavelength of the first cyan multi-quantum well layer is 490 nm, the emission wavelength of the second long-wavelength blue multi-quantum well layer is 460 nm, the emission wavelength of the third short-wavelength blue multi-quantum well layer is 445 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430 nm.

[0129] In this embodiment, the barrier layer of each multi-quantum well layer includes a Si-doped front GaN layer, an undoped Si AlGaN layer, and a Si-doped rear GaN layer sequentially stacked along the epitaxial direction, and the Al component contents of the undoped Si AlGaN layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, and the total thickness of a single barrier layer decreases in sequence.

[0130] In this embodiment, the Al component contents of the undoped Si AlGaN layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer are x1, x2, x3, and x4 in sequence, where x1 is 0.03, x2 is 0.02, x3 is 0.01, and x4 is 0.005.

[0131] In this embodiment, the growth temperatures of the Si-doped front GaN layer and the Si-doped rear GaN layer of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer increase in sequence, the Si doping concentrations decrease in sequence, the total thicknesses of the Si-doped front GaN layer and the Si-doped rear GaN layer in a single barrier layer decrease in sequence, and the single-layer thicknesses and growth temperatures of the undoped Si AlGaN layers are the same.

[0132] In this embodiment, in the first blue-green multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 820 °C, and the Si doping concentration is 4×10 17 / cm 3 ; in the second long-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 830 °C, and the Si doping concentration is 3×10 17 / cm 3 ; in the third short-wavelength blue multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 850 °C, and the Si doping concentration is 2×10 17 / cm 3 ; in the fourth violet multi-quantum well layer, the growth temperature of the pre-Si-doped GaN layer and the post-Si-doped GaN layer is 880 °C, and the Si doping concentration is 1×10 17 / cm 3 .

[0133] In this embodiment, in the first blue-green multi-quantum well layer, the total thickness h1 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 10 nm; in the second long-wavelength blue multi-quantum well layer, the total thickness h2 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 8 nm; in the third short-wavelength blue multi-quantum well layer, the total thickness h3 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 6 nm; in the fourth violet multi-quantum well layer, the total thickness h4 of the pre-Si-doped GaN layer and the post-Si-doped GaN layer within a single barrier layer is 4 nm.

[0134] In this embodiment, the single-layer thickness of each unintentionally Si-doped AlGaN layer is 3 nm, and the growth temperature is 820 °C.

[0135] In this embodiment, the well layers of each multi-quantum well layer include unintentionally Si-doped InGaN layers, and the In component content of the unintentionally Si-doped InGaN layers in the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases in sequence, and the growth temperature increases in sequence.

[0136] In this embodiment, the number of periods of the first blue-green multi-quantum well layer is 1, the number of periods of the second long-wavelength blue multi-quantum well layer is 2, the number of periods of the third short-wavelength blue multi-quantum well layer is 2, and the number of periods of the fourth violet multi-quantum well layer is 1.

[0137] Furthermore, this embodiment provides a white LED light source, including a fluorescent glue layer and the above-mentioned LED chip, and the fluorescent glue layer includes red phosphor and green phosphor.

[0138] Comparative Example 1 The difference between this comparative example and Example 1 is that in this comparative example, the Al component content of the AlGaN layer without deliberately doping Si remains the same between each multiple quantum well layer of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer, and is all 0.15.

[0139] Comparative Example 2 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-wavelength blue multi-quantum well layer is 3.

[0140] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, the second long-wavelength blue multi-quantum well layer is not provided, and the number of periods of the first cyan multi-quantum well layer is 3.

[0141] Comparative Example 4 The difference between this comparative example and Example 1 is that in this comparative example, the third short-wavelength blue multi-quantum well layer is not provided, and the number of periods of the fourth violet multi-quantum well layer is 3.

[0142] Comparative Example 5 The difference between this comparative example and Example 1 is that in this comparative example, the fourth violet multi-quantum well layer is not provided, and the number of periods of the third short-wavelength blue multi-quantum well layer is 3.

[0143] Comparative Example 6 The difference between this comparative example and Example 1 is that in this comparative example, only the third short-wavelength blue multi-quantum well layer is provided in the light-emitting layer, and the number of periods of the third short-wavelength blue multi-quantum well layer is 6.

[0144] The electrical parameters of Examples 1 to 5 and Comparative Examples 1 to 6 were tested, the luminous efficiency improvement rate of the remaining experimental groups relative to Comparative Example 6 was calculated, and the color rendering performance of each experimental group was tested. The test results are as follows:

[0145] 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.

[0146] Among them, by comparing Example 1 with Comparative Examples 1 to 6, it can be seen that the light-emitting layer structure of the present invention combining the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer can form a more continuous, smoother, and more natural light-like spectrum, effectively improving the color rendering performance of the white light source.

[0147] Comparing Comparative Example 1 to Example 3, it can be seen that the changes in the emission wavelength of each multi-quantum well layer and the bandgap width of the barrier layer will affect the color rendering performance and luminous efficiency.

[0148] Comparing Example 1 and Example 4, it can be seen that the decreasing design of the bandgap width of the barrier layer of each multi-quantum well layer from the first blue-green multi-quantum well layer to the fourth violet multi-quantum well layer combined with the decreasing design of the thickness of the barrier layer of each multi-quantum well layer from the first blue-green multi-quantum well layer to the fourth violet multi-quantum well layer is more conducive to improving the luminous efficiency.

[0149] Comparing Example 1, Example 5 and Comparative Example 1, it can be seen that the decreasing setting of the emission wavelength of each multi-quantum well layer from the first blue-green multi-quantum well layer to the fourth violet multi-quantum well layer combined with the decreasing setting of the bandgap width of the barrier layer of each multi-quantum well layer from the first blue-green multi-quantum well layer to the fourth violet multi-quantum well layer can effectively improve the luminous efficiency.

[0150] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the technical content prompted above within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope 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 that are sequentially arranged along the epitaxial direction; The light-emitting layer includes a first cyan multi-quantum well layer, a second long-wavelength blue multi-quantum well layer, a third short-wavelength blue multi-quantum well layer, and a fourth violet multi-quantum well layer that are sequentially stacked along the epitaxial direction; The first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer are all periodic structures formed by alternately stacking well layers and barrier layers, The emission wavelengths of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, The band gaps of the barrier layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence.

2. The multi-band LED chip according to claim 1, wherein, The emission wavelength of the first cyan multi-quantum well layer is 490 nm to 500 nm, the emission wavelength of the second long-wavelength blue multi-quantum well layer is 460 nm to 480 nm, the emission wavelength of the third short-wavelength blue multi-quantum well layer is 445 nm to 460 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430 nm to 445 nm.

3. A multi-band LED chip according to claim 1, characterized in that, Each of the barrier layers includes a pre-GaN layer doped with Si, an undoped AlGaN layer without intentional Si doping, and a post-GaN layer doped with Si that are sequentially stacked along the epitaxial direction, and the Al component contents of the undoped AlGaN layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, and the total thickness of each barrier layer decreases in sequence.

4. The multi-band LED chip according to claim 3, characterized in that, The Al component contents of the undoped AlGaN layers of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer are x1, x2, x3, and x4 in sequence, where 0.03 ≤ x1 ≤ 0.15, 0.02 ≤ x2 ≤ 0.12, 0.01 ≤ x3 ≤ 0.1, and 0 < x4 ≤ 0.

08.

5. A multi-band LED chip according to claim 3, characterized in that, The growth temperatures of the pre-GaN layer doped with Si and the post-GaN layer doped with Si of the first cyan multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer increase in sequence, the Si doping concentrations decrease in sequence, the total thicknesses of the pre-GaN layer doped with Si and the post-GaN layer doped with Si in each barrier layer decrease in sequence, and the single-layer thicknesses and growth temperatures of the undoped AlGaN layers are the same.

6. The multi-band LED chip according to claim 5, characterized in that, In the first blue-green multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped rear 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-wavelength blue light multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 825°C to 918°C, and the Si doping concentration is 1.3×10 17 / cm 3 ~7.3×10 17 / cm 3 ; In the third short-wavelength blue light multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 830°C to 923°C, and the Si doping concentration is 1.1×10 17 / cm 3 ~6.7×10 17 / cm 3 ; In the fourth ultraviolet multi-quantum well layer, the growth temperature of the Si-doped front GaN layer and the Si-doped rear GaN layer is 835°C to 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 blue-green multi-quantum well layer, the total thickness of the Si-doped pre-GaN layer and the Si-doped post-GaN layer in a single barrier layer is 6 nm to 12 nm; in the second long-wavelength blue multi-quantum well layer, the total thickness of the Si-doped pre-GaN layer and the Si-doped post-GaN layer in a single barrier layer is 5.2 nm to 11.2 nm; in the third short-wavelength blue multi-quantum well layer, the total thickness of the Si-doped pre-GaN layer and the Si-doped post-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 pre-GaN layer and the Si-doped post-GaN layer in a single barrier layer is 4 nm to 10 nm; and / or, The single-layer thickness of each undoped Si AlGaN layer is 1 nm to 5 nm, and the growth temperature is 780 °C to 928 °C.

7. A multi-band LED chip according to claim 1, wherein Each well layer includes an undoped Si InGaN layer, and the In component content of the undoped Si InGaN layer in the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases in sequence, and the growth temperature increases in sequence.

8. A preparation method of a multi-band LED chip, characterized in that, Including: Providing a substrate; Depositing an epitaxial layer on the substrate, 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 includes a first blue-green multi-quantum well layer, a second long-wavelength blue multi-quantum well layer, a third short-wavelength blue multi-quantum well layer, and a fourth violet multi-quantum well layer stacked in sequence along the epitaxial direction; The first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength 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 blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence, The band gaps of the barrier layers of the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decrease in sequence.

9. The preparation method according to claim 8, characterized in that, The emission wavelength of the first blue-green multi-quantum well layer is 490 nm to 500 nm, the emission wavelength of the second long-wavelength blue multi-quantum well layer is 460 nm to 480 nm, the emission wavelength of the third short-wavelength blue multi-quantum well layer is 445 nm to 460 nm, and the emission wavelength of the fourth violet multi-quantum well layer is 430 nm to 445 nm; and / or, Each of the barrier layers includes a Si-doped front GaN layer, an undoped Si AlGaN layer, and a Si-doped rear GaN layer that are sequentially stacked in the epitaxial direction. The Al component content of the undoped Si AlGaN layer of the first blue-green multi-quantum well layer, the second long-wavelength blue multi-quantum well layer, the third short-wavelength blue multi-quantum well layer, and the fourth violet multi-quantum well layer decreases in sequence, and the total thickness of a single barrier layer decreases in sequence.

10. A white light LED light source, characterized in that, It includes a fluorescent glue layer and an LED chip according to any one of claims 1 to 7, and the fluorescent glue layer includes red phosphor and green phosphor.

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