Multi-band LED epitaxial structure and preparation method thereof

Abstract

The application relates to the technical field of light-emitting diodes, and discloses a multi-waveband LED epitaxial structure and a preparation method thereof. The multi-waveband LED epitaxial structure comprises a multi-quantum well light-emitting layer, the multi-quantum well light-emitting layer comprises a long-wave blue light multi-quantum well layer, a short-wave blue light multi-quantum well layer, a long-wave violet light multi-quantum well layer and a short-wave violet light multi-quantum well layer, all of which are periodic structures, and each single period comprises an N-polarity well front insertion layer, a Ga-polarity quantum well layer, an N-polarity well rear insertion layer and an N-polarity quantum barrier layer; the N-polarity well front insertion layer comprises an In x Ga 1‑x N layer, an Al a Ga 1‑a N layer and an In y Ga 1‑y N layer; the Ga-polarity quantum well layer is an In z Ga 1‑z N layer; the N-polarity well rear insertion layer comprises an In m Ga 1‑m N layer, an Al b Ga 1‑b N layer and an undoped GaN layer; and the N-polarity quantum barrier layer is an N-polarity GaN layer. By implementing the application, a healthy full-spectrum white light LED light source with a high color rendering index can be generated, and the light-emitting efficiency is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light-emitting diode, in particular to a multi-band LED epitaxial structure and a preparation method thereof. BACKGROUND

[0002] LED light source has the advantages of small size, long life, high efficiency, etc., and can be used continuously for hundreds of thousands of hours. LED light source has become mainstream in the lighting field. With the continuous expansion of the application field of LED light source, higher requirements are put forward for the light-emitting characteristics of LED light source. Among them, the expansion of the light-emitting spectral range of LED light source has become one of the main improvement directions. Such products are named full-spectrum white LED light source in the industry. Full spectrum refers to a spectrum containing ultraviolet light, visible light and infrared light, and the ratio of red, green and blue in the visible light part is similar to sunlight, and the color rendering index is close to 100. The spectrum of sunlight can be called full spectrum.

[0003] The white light LED device on the market usually uses fluorescent glue to coat the blue light LED chip to emit white light. However, in the spectral curve of the full-spectrum white LED light source, the spectral curve of the blue light band fluctuates greatly and has poor stability. As early as 1966, Nell et al. found that the irradiation of blue light would cause damage to the retinal cells, resulting in a decrease or even loss of vision. Among them, the short-wave blue light with a wavelength of 400-450 nm has the greatest degree of harm to the retina. At the 2010 International Optical Society Annual Meeting, top optical experts around the world unanimously pointed out that short-wave blue light has extremely high energy and can penetrate the lens to reach the retina. Blue light irradiation of the retina will produce free radicals, and these free radicals will cause the decline of retinal pigment epithelial cells, and the decline of epithelial cells will cause the lack of nutrients for photosensitive cells, thereby causing vision damage, and these damages are irreversible. In view of the shortcomings of the current full-spectrum white LED light source, the structure and process of the blue light LED chip are further optimized and researched, so as to produce a full-spectrum white LED light source with small short-wave blue light proportion, small damage to human eye retina cells, high color rendering index and closer to the sunlight spectrum through the multi-band LED chip to excite the red and green mixed fluorescent powder layer. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a multi-band LED epitaxial structure and a preparation method thereof, which produces a full-spectrum white LED light source by exciting a mixed fluorescent powder layer through a multi-band LED chip, has small short-wave blue light proportion, small damage to human eye retina cells, and realizes a healthy full-spectrum white LED light source with high color rendering index.

[0005] To solve the above technical problems, the first aspect of the present application provides a multi-band LED epitaxial structure, comprising a substrate, a buffer layer, an N-type semiconductor layer, a low-temperature stress release layer, a multi-quantum well light-emitting layer, an electron blocking layer and a P-type semiconductor layer which are sequentially stacked, wherein,

[0006] The multi-quantum well light-emitting layer comprises a long-wave blue multi-quantum well layer, a short-wave blue multi-quantum well layer, a long-wave violet multi-quantum well layer and a short-wave violet multi-quantum well layer which are sequentially stacked, and the long-wave blue multi-quantum well layer, the short-wave blue multi-quantum well layer, the long-wave violet multi-quantum well layer and the short-wave violet multi-quantum well layer are all periodic structures, and each single period comprises an N-polarity well front insertion layer, a Ga-polarity quantum well layer, an N-polarity well rear insertion layer and an N-polarity quantum barrier layer which are sequentially stacked;

[0007] The N-polarity well front insertion layer comprises In x Ga 1-x N layers, Al a Ga 1-a N layers and In y Ga 1-y N layers which are sequentially grown;

[0008] The Ga-polarity quantum well layer is an In z Ga 1-z N layer;

[0009] The N-polarity well rear insertion layer comprises In m Ga 1-m N layers, Al b Ga 1-b N layers and an undoped GaN layer which are sequentially grown;

[0010] The N-polarity quantum barrier layer is an N-polarity GaN layer.

[0011] As an improvement of the above scheme, the long-wave blue multi-quantum well layer has a light-emitting wavelength of λ1, the short-wave blue multi-quantum well layer has a light-emitting wavelength of λ2, the long-wave violet multi-quantum well layer has a light-emitting wavelength of λ3, and the short-wave violet multi-quantum well layer has a light-emitting wavelength of λ4, and λ1>λ2>λ3>λ4.

[0012] As an improvement of the above scheme, the In x Ga 1-x N layer is an N-type doped InGaN single-layer structure or an N-type doped InGaN multi-layer structure, and the doping concentration is 1.16×10 17 / cm 3 -6.78×10 17 / cm 3 , and 0≤x≤0.025; and the In x Ga 1-xThe growth thickness of the N layer is less than or equal to 0.38 nm;

[0013] The Al a Ga 1-a The N-layer is an undoped N-polar AlGaN layer, with 0.01 ≤ a ≤ 0.15. a Ga 1- a The growth thickness of the N layer is less than or equal to 0.56 nm;

[0014] The In y Ga 1-y The N-layer is an undoped N-polar InGaN layer, where the In content (y) increases with increasing growth thickness, and 0 ≤ y ≤ 0.19. y Ga 1-y The growth thickness of the N layer is less than or equal to 0.75 nm;

[0015] The In m Ga 1-m The N-layer is an undoped N-polar InGaN layer, where the In content m decreases with increasing growth thickness, 0 ≤ m ≤ 0.19; the In... m Ga 1-m The growth thickness of the N layer is less than or equal to 0.75 nm;

[0016] The Al b Ga 1-b The N-layer is an undoped N-polar AlGaN layer, 0 ≤ b ≤ 0.12, wherein the Al b Ga 1-b The growth thickness of the N layer is less than or equal to 0.56 nm;

[0017] The undoped GaN layer is either a single-layer N-polar GaN structure or a multilayer N-polar GaN structure without intentional doping, and the growth thickness of the undoped GaN layer is less than or equal to 0.38 nm.

[0018] As an improvement to the above solution, the In z Ga 1-z The N layer is an InGaN layer that is not intentionally doped; the In z Ga 1- z The growth thickness of the N layer is 2.1 nm-4.8 nm;

[0019] In long-wavelength blue light multi-quantum well layer z Ga 1-z The proportion of In component in the N layer is greater than that in the short-wavelength blue light multi-quantum-well layer. z Ga 1-zThe In composition percentage of the N layer, and the In content of the short-wavelength blue light multi-quantum well layer. z Ga 1-z The proportion of In in the N-layer is greater than that in the long-wavelength violet light multi-quantum-well layer. z Ga 1-z The In composition percentage of the N-layer, and the In content of the long-wavelength violet multi-quantum well layer. z Ga 1-z The proportion of In component in the N layer is greater than that in the short-wavelength violet quantum well layer. z Ga 1-z The proportion of In component in the N layer.

[0020] As an improvement to the above scheme, the N-polar GaN layer is an N-type doped GaN layer with a doping concentration of 2.1 × 10⁻⁶. 17 / cm 3 -8.7×10 17 / cm 3 The thickness of the N-polar GaN layer is 6.2 nm to 13.9 nm.

[0021] The growth temperature of the N-polar GaN layer in the long-wavelength blue light multi-quantum well layer is less than or equal to the growth temperature of the N-polar GaN layer in the short-wavelength blue light multi-quantum well layer, the growth temperature of the N-polar GaN layer in the short-wavelength blue light multi-quantum well layer is less than or equal to the growth temperature of the N-polar GaN layer in the long-wavelength violet light multi-quantum well layer, and the growth temperature of the N-polar GaN layer in the long-wavelength violet light multi-quantum well layer is less than or equal to the growth temperature of the N-polar GaN layer in the short-wavelength violet light multi-quantum well layer.

[0022] As an improvement to the above scheme, the number of cycles of the long-wavelength blue light multi-quantum well layer is 1-3, and a single cycle includes a first N-polar well pre-insertion layer, a first Ga-polar quantum well layer, a first N-polar well post-insertion layer and a first N-polar quantum barrier layer stacked sequentially.

[0023] The first N-polar well pre-insertion layer comprises In layers grown sequentially. x1 Ga 1-x1 N layer, Al a1 Ga 1-a1 N layers and In y1 Ga 1-y1 N layers; the first Ga polar quantum well layer is In. z1 Ga 1-z1 N layers; the first N-polar well post-insertion layer comprises In layers grown sequentially. m1 Ga 1-m1 N layer, Al b1 Ga 1-b1 The N-layer and the first undoped GaN layer; the first N-polar quantum barrier layer is the first N-polar GaN layer;

[0024] The short-wavelength blue light multi-quantum well layer has 2-5 cycles, and each cycle includes a second N-polar well pre-insertion layer, a second Ga-polar quantum well layer, a second N-polar well post-insertion layer, and a second N-polar quantum barrier layer stacked sequentially.

[0025] The second N-polar well pre-insertion layer comprises In layers grown sequentially. x2 Ga 1-x2 N layer, Al a2 Ga 1-a2 N layers and In y2 Ga 1-y2 N-layer; the second Ga polar quantum well layer is In. z2 Ga 1-z2 N layers; the second N-polar well post-insertion layer comprises In layers grown sequentially. m2 Ga 1-m2 N layer, Al b2 Ga 1-b2 The N-layer and the second undoped GaN layer; the second N-polar quantum barrier layer is a second N-polar GaN layer;

[0026] The number of cycles of the long-wavelength violet multi-quantum well layer is 2-5, and a single cycle includes a third N-polar well pre-insertion layer, a third Ga-polar quantum well layer, a third N-polar well post-insertion layer and a third N-polar quantum barrier layer stacked sequentially.

[0027] The third N-polar well pre-insertion layer comprises In layers grown sequentially. x3 Ga 1-x3 N layer, Al a3 Ga 1-a3 N layers and In y3 Ga 1-y3 N layers; the third Ga polar quantum well layer is In. z3 Ga 1-z3 N layers; the third N-polar well post-insertion layer comprises In layers grown sequentially. m3 Ga 1-m3 N layer, Al b3 Ga 1-b3 The N-layer and the third undoped GaN layer; the third N-polar quantum barrier layer is a third N-polar GaN layer;

[0028] The number of cycles of the short-wavelength violet quantum well layer is 1-3, and a single cycle includes a fourth N-polar well pre-insertion layer, a fourth Ga-polar quantum well layer, a fourth N-polar well post-insertion layer and a fourth N-polar quantum barrier layer stacked sequentially.

[0029] The fourth N-polar well pre-insertion layer comprises In layers grown sequentially. x4 Ga 1-x4 N layer, Ala4 Ga 1-a4 N layers and In y4 Ga 1-y4 N layers; the fourth Ga polar quantum well layer is In. z4 Ga 1-z4 N layers; the fourth N-polar well post-insertion layer comprises In layers grown sequentially. m4 Ga 1-m4 N layer, Al b4 Ga 1-b4 The N-layer and the fourth undoped GaN layer; the fourth N-polar quantum barrier layer is a fourth N-polar GaN layer.

[0030] As an improvement to the above scheme, z1 > z2 > z3 > z4, and the growth temperature of the first N-polar GaN layer is T1, the growth temperature of the second N-polar GaN layer is T2, the growth temperature of the third N-polar GaN layer is T3, and the growth temperature of the fourth N-polar GaN layer is T4, satisfying: T1 ≤ T2, T2 ≤ T3, T3 ≤ T4;

[0031] a1≥b1, a2≥b2, a3≥b3, a4≥b4, and a1≥a4, a4≥a2, a2≥a3, b1≥b4, b4≥b2, b2≥b3; b1≥a4, b4≥a2, b2≥a3.

[0032] As an improvement to the above solution, the In y1 Ga 1-y1 In layer N, the proportion of In component y1 increases from 0 ≤ y1 ≤ 0.10 to 0.15 ≤ y1 ≤ 0.19 with increasing growth thickness. m1 Ga 1-m1 In the N layer, the proportion of In component m1 decreases from 0.15≤m1≤0.19 to 0≤m1≤0.10 as the growth thickness increases;

[0033] The In y2 Ga 1-y2 In layer N, the proportion of In component y2 increases from 0 ≤ y2 ≤ 0.08 to 0.13 ≤ y2 ≤ 0.17 with increasing growth thickness. m2 Ga 1-m2 In the N layer, the proportion of In component m2 decreases from 0.13≤m2≤0.17 to 0≤m2≤0.08 with increasing growth thickness;

[0034] The In y3 Ga 1-y3 In layer N, the proportion of In component y3 increases from 0 ≤ y3 ≤ 0.06 to 0.11 ≤ y3 ≤ 0.15 with increasing growth thickness. m3 Ga 1-m3In the N layer, the proportion of In component m3 decreases from 0.11≤m3≤0.15 to 0≤m3≤0.06 with increasing growth thickness;

[0035] The In y4 Ga 1-y4 In layer N, the proportion of In component y4 increases from 0 ≤ y4 ≤ 0.05 to 0.09 ≤ y4 ≤ 0.12 with increasing growth thickness. m4 Ga 1-m4 In the N layer, the proportion of In component m4 decreases from 0.09≤m4≤0.12 to 0≤m4≤0.05 with increasing growth thickness;

[0036] 0.05≤a1≤0.15, 0.03≤b1≤0.12; 0.02≤a2≤0.10, 0.01≤b2≤0.08; 0.01≤a3≤0.08, 0≤b3≤0.07; 0.03≤a4≤0.12, 0.02≤b4≤0.10;

[0037] 0.17≤z1≤0.19, 0.15≤z2≤0.17, 0.12≤z3≤0.15, 0.09≤z4≤0.12;

[0038] The growth temperature T1 of the first N-polar GaN layer is 805℃-916℃, and the growth pressure is 30 torr-360 torr; the growth temperature T2 of the second N-polar GaN layer is 815℃-926℃, and the growth pressure is 30 torr-360 torr; the growth temperature T3 of the third N-polar GaN layer is 825℃-936℃, and the growth pressure is 30 torr-360 torr; the growth temperature T4 of the fourth N-polar GaN layer is 835℃-950℃, and the growth pressure is 30 torr-360 torr.

[0039] The second aspect of the present invention also provides a method for fabricating the multi-band LED epitaxial structure, comprising the following steps:

[0040] (1) Provide a substrate;

[0041] (2) A buffer layer is grown on the substrate;

[0042] (3) An N-type semiconductor layer is grown on the buffer layer;

[0043] (4) A low-temperature stress relief layer is grown on the N-type semiconductor layer;

[0044] (5) A multi-quantum-well light-emitting layer is grown on the low-temperature stress-relieving layer;

[0045] (6) An electron blocking layer is grown on the multi-quantum-well light-emitting layer;

[0046] (7) A P-type semiconductor layer is grown on the electron blocking layer;

[0047] The multi-quantum-well emitting layer comprises a long-wavelength blue multi-quantum-well layer, a short-wavelength blue multi-quantum-well layer, a long-wavelength violet multi-quantum-well layer, and a short-wavelength violet final quantum well layer, all stacked sequentially. Each of the long-wavelength blue multi-quantum-well layer, the short-wavelength blue multi-quantum-well layer, the long-wavelength violet multi-quantum-well layer, and the short-wavelength violet final quantum well layer is a periodic structure, and each period comprises a pre-insertion layer of an N-polarity well, a Ga-polarity quantum well layer, a post-insertion layer of an N-polarity well, and an N-polarity quantum barrier layer, all stacked sequentially.

[0048] The N-polar well pre-insertion layer comprises In layers grown sequentially. x Ga 1-x N layer, Al a Ga 1-a N layers and In y Ga 1-y N layers; the Ga polar quantum well layer is In z Ga 1-z N layers; the N-polar well post-insertion layer comprises In layers grown sequentially. m Ga 1- m N layer, Al b Ga 1-b The N-layer is an undoped GaN layer; the N-polar quantum barrier layer is an N-polar GaN layer.

[0049] As an improvement to the above scheme, step (5) involves growing a multi-quantum-well light-emitting layer on the low-temperature stress-relieving layer, including the following steps:

[0050] The obtained epitaxial material layer is annealed, and then an N-polar well pre-insertion layer is grown on the obtained epitaxial material layer.

[0051] A Ga polar quantum well layer is grown on the N-polar well pre-insertion layer, and the resulting epitaxial material layer is annealed.

[0052] An N-polar well is grown on the annealed Ga polar quantum well layer, followed by an insertion layer;

[0053] An N-polar quantum barrier layer is grown on the N-polar well back insertion layer;

[0054] The annealing process includes: the obtained epitaxial material layer is held in full NH3 for 8s-200s, wherein the annealing temperature is 820℃-1100℃ and the pressure is 50torr-600torr.

[0055] Implementing this invention has the following beneficial effects:

[0056] The multi-band LED epitaxial structure in this application is used to form a multi-band LED chip. It uses an excitation light source with four bands to excite a red and green mixed phosphor layer to generate a full-spectrum white LED light source. Compared with a blue LED chip with only one band, it has a smaller proportion of short-wavelength blue light below 450nm, which causes less damage to human retinal cells. Moreover, since its excitation light source has four bands, the full-spectrum white light it generates is closer to the solar spectrum, thereby realizing a healthy full-spectrum white LED light source with a high color rendering index.

[0057] The long-wavelength blue light multi-quantum-well layer, short-wavelength blue light multi-quantum-well layer, long-wavelength violet light multi-quantum-well layer, and short-wavelength violet light final quantum-well layer are all periodic structures. Each period includes a sequentially stacked N-polar well pre-insertion layer, Ga-polar quantum-well layer, N-polar well post-insertion layer, and N-polar quantum barrier layer. The multi-quantum-well light-emitting layer structure designed in this invention utilizes the opposite polarization electric field directions of Ga-polar nitride and N-polar nitride to significantly improve the band bending phenomenon caused by the polarization electric field in the multi-quantum-well light-emitting layer. This increases the coupling degree between the electron and hole wave functions in the multi-quantum-well light-emitting layer, thereby improving the radiative recombination efficiency and ultimately enhancing the luminous efficiency of the multi-band LED chip. Attached Figure Description

[0058] Figure 1 : A schematic diagram of a multi-band LED epitaxial structure in this invention;

[0059] Figure 2 : A schematic diagram of the structure of a multi-quantum-well light-emitting layer in this invention;

[0060] Figure 3 : A schematic diagram of a long-wavelength blue light multi-quantum well layer in this invention;

[0061] Figure 4 : A schematic diagram of a short-wavelength blue light multi-quantum well layer in this invention;

[0062] Figure 5 : A schematic diagram of a long-wavelength violet light multi-quantum well layer in this invention;

[0063] Figure 6 : A schematic diagram of the structure of a short-wavelength violet quantum well layer in this invention.

[0064] Figure label:

[0065] 100 - Substrate; 200 - Buffer layer; 300 - N-type semiconductor layer; 400 - Low-temperature stress relief layer; 500 - Multi-quantum well light-emitting layer; 510 - Long-wavelength blue light multi-quantum well layer; 511 - First N-polarity well pre-insertion layer; 5111 - In x1 Ga 1-x1 N layer; 5112-Ala1 Ga 1-a1 N layers; 5113-In y1 Ga 1-y1 N-layer; 512-First Ga polar quantum well layer; 513-In insertion layer after the first N-polar well; 5131-In m1 Ga 1-m1 N layer; 5132-Al b1 Ga 1-b1 N-layer; 5133-first undoped GaN layer; 514-first N-polar quantum barrier layer; 520-short-wavelength blue light multi-quantum-well layer; 521-second N-polar well pre-insertion layer; 5211-In x2 Ga 1-x2 N layer; 5212-Al a2 Ga 1- a2 Nth layer; 5213-In y2 Ga 1-y2 N-layer; 522-Second Ga polar quantum well layer; 523-Second N-polar well back insertion layer; 5231-In m2 Ga 1-m2 N layer; 5232-Al b2 Ga 1-b2 N-layer; 5233-Second undoped GaN layer; 524-Second N-polar quantum barrier layer; 530-Long-wavelength violet multi-quantum-well layer; 531-Third N-polar well pre-insertion layer; 5311-In x3 Ga 1-x3 N layer; 5312-Al a3 Ga 1-a3 Nth layer; 5313-In y3 Ga 1-y3 N-layer; 532-Third Ga polar quantum well layer; 533-Third N-polar well back insertion layer; 5331-In m3 Ga 1- m3 N layer; 5332-Al b3 Ga 1-b3 N-layer; 5333-Third undoped GaN layer; 534-Third N-polar quantum barrier layer; 540-Short-wavelength violet quantum well layer; 541-Fourth N-polar well pre-insertion layer; 5411-In x4 Ga 1-x4 N layer; 5412-Al a4 Ga 1-a4 Nth layer; 5413-In y4 Ga 1-y4 N-layer; 542-Fourth Ga polar quantum well layer; 543-Fourth N-polar well back insertion layer; 5431-In m4 Ga 1-m4 N layer; 5432-Alb4 Ga 1-b4 N-layer; 5433-fourth undoped GaN layer; 544-fourth N-polar quantum barrier layer; 600-electron blocking layer; 700-P-type semiconductor layer. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described in further detail below.

[0067] In the description of this application, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "top", "bottom", "inner", and "outer" are based on the orientation or positional relationship shown in the accompanying drawings. They are intended only to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the components referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0068] To address the above problems, the first aspect of this invention provides a multi-band LED epitaxial structure, please refer to [link / reference]. Figure 1 The system includes a substrate 100, a buffer layer 200, an N-type semiconductor layer 300, a low-temperature stress relief layer 400, a multi-quantum well light-emitting layer 500, an electron blocking layer 600, and a P-type semiconductor layer 700, which are stacked sequentially. The multi-quantum well light-emitting layer 500 includes a long-wavelength blue light multi-quantum well layer 510, a short-wavelength blue light multi-quantum well layer 520, a long-wavelength violet light multi-quantum well layer 530, and a short-wavelength violet light quantum well layer 540, which are stacked sequentially.

[0069] The long-wavelength blue light multi-quantum well layer 510 emits light at wavelength λ1, the short-wavelength blue light multi-quantum well layer 520 emits light at wavelength λ2, the long-wavelength violet light multi-quantum well layer 530 emits light at wavelength λ3, and the short-wavelength violet light multi-quantum well layer 540 emits light at wavelength λ4, where λ1 > λ2 > λ3 > λ4.

[0070] The multi-band LED epitaxial structure disclosed in this application is used to form a multi-band LED chip. By using an excitation light source with four wavelengths to excite a red and green mixed phosphor layer, a full-spectrum white LED light source is generated. Compared with a blue LED chip with only one wavelength, it has a smaller proportion of short-wavelength blue light below 450nm, which causes less damage to human retinal cells. Moreover, since its excitation light source has four wavelengths, the full-spectrum white light generated is closer to the solar spectrum, thereby realizing a healthy full-spectrum white LED light source with a high color rendering index.

[0071] Optionally, λ1 is 464nm-480nm, λ2 is 449nm-465nm, λ3 is 434nm-450nm, and λ4 is 420nm-435nm.

[0072] Specifically, the long-wavelength blue light multi-quantum-well layer 510, the short-wavelength blue light multi-quantum-well layer 520, the long-wavelength violet light multi-quantum-well layer 530, and the short-wavelength violet light final quantum-well layer 540 are all periodic structures. Each period includes a sequentially stacked N-polar well pre-insertion layer, a Ga-polar quantum-well layer, an N-polar well post-insertion layer, and an N-polar quantum barrier layer. The structure of the multi-quantum-well emitting layer 500 designed in this invention utilizes the opposite polarization electric field directions of the Ga-polar nitride and the N-polar nitride, which can significantly improve the band bending phenomenon caused by the polarization electric field in the multi-quantum-well emitting layer 500. This improves the coupling degree between the electron and hole wave functions in the multi-quantum-well emitting layer 500, thereby increasing the radiative recombination efficiency in the multi-quantum-well emitting layer 500 and ultimately improving the luminous efficiency of the multi-band LED chip.

[0073] Preferably, the N-polar well pre-insertion layer comprises In layers grown sequentially. x Ga 1-x N layer, Al a Ga 1-a N layers and In y Ga 1-y N layers.

[0074] Wherein, the In x Ga 1-x The N-layer is either an N-type doped InGaN monolayer structure or an N-type doped InGaN multilayer structure, specifically a low-doped structure with a doping concentration of 1.16 × 10⁻⁶. 17 / cm 3 -6.78×10 17 / cm 3 The In component percentage (x) is also relatively low, 0 ≤ x ≤ 0.025; the Al a Ga 1-a The N-layer is an undoped N-polar AlGaN layer, with 0.01 ≤ a ≤ 0.15; the In... y Ga 1-y The N layer is an N-polar InGaN layer without intentional doping, and the proportion of In component y increases with the increase of growth thickness, 0≤y≤0.19.

[0075] Optionally, the In x Ga 1-x The growth thickness of the N layer is less than or equal to 0.38 nm; the Al a Ga 1-a The growth thickness of the N layer is less than or equal to 0.56 nm; the In y Ga 1-y The growth thickness of the N layer is less than or equal to 0.75 nm; the Al a Ga 1-a The N-layer has a growth thickness of 0.03 nm to 0.56 nm; the Iny Ga 1-y The growth thickness of the N layer is 0.03nm-0.75nm.

[0076] Preferably, the Ga polar quantum well layer is In. z Ga 1-z N layers, the In z Ga 1-z The N-layer is an InGaN layer that is not intentionally doped. z Ga 1-z The growth thickness of the N layer is 2.1 nm to 4.8 nm.

[0077] Furthermore, the In component has a relatively high proportion z in the Ga polar quantum well layer, and the In component in the long-wavelength blue light multi-quantum well layer 510 is relatively high. z Ga 1-z The proportion of In component in the N layer is greater than that in the In of the short-wavelength blue light multi-quantum well layer 520. z Ga 1-z The In composition percentage of the N layer, and the In content of the short-wavelength blue light multi-quantum well layer 520. z Ga 1-z The proportion of In in the N layer is greater than that of In in the long-wavelength violet light multi-quantum-well layer 530. z Ga 1-z The In composition percentage of the N layer, and the In content of the long-wavelength violet multi-quantum-well layer 530. z Ga 1-z The proportion of In component in the N layer is greater than that in the In 540 short-wavelength violet quantum well layer. z Ga 1-z The proportion of In component in the N layer.

[0078] Preferably, the N-polar well post-insertion layer comprises In layers grown sequentially. m Ga 1-m N layer, Al b Ga 1-b N-layer and undoped GaN layer. Wherein, the In... m Ga 1-m The N-layer is an undoped N-polar InGaN layer, where the In content m decreases with increasing growth thickness, 0 ≤ m ≤ 0.19; the Al... b Ga 1-b The N-layer is an undoped N-polar AlGaN layer with 0 ≤ b ≤ 0.12; the undoped GaN layer is an undoped N-polar GaN single-layer structure or an undoped N-polar GaN multilayer structure.

[0079] Optionally, the In m Ga 1-mThe growth thickness of the N layer is less than or equal to 0.75 nm; the Al b Ga 1-b The growth thickness of the N-layer is less than or equal to 0.56 nm; the growth thickness of the undoped GaN layer is less than or equal to 0.38 nm; the Al b Ga 1-b The thickness of the N-layer is 0.03 nm to 0.56 nm; the thickness of the undoped GaN layer is 0.03 nm to 0.38 nm.

[0080] Preferably, the N-polar quantum barrier layer is an N-polar GaN layer, more preferably an N-type doped GaN layer, specifically a lightly doped layer with a doping concentration of 2.1 × 10⁻⁶. 17 / cm 3 -8.7×10 17 / cm 3 .

[0081] Optionally, the thickness of the N-polar GaN layer is 6.2 nm to 13.9 nm.

[0082] Furthermore, the growth temperature of the N-polar GaN layer in the long-wavelength blue multi-quantum well layer 510 is less than or equal to the growth temperature of the N-polar GaN layer in the short-wavelength blue multi-quantum well layer 520, the growth temperature of the N-polar GaN layer in the short-wavelength blue multi-quantum well layer 520 is less than or equal to the growth temperature of the N-polar GaN layer in the long-wavelength violet multi-quantum well layer 530, and the growth temperature of the N-polar GaN layer in the long-wavelength violet multi-quantum well layer 530 is less than or equal to the growth temperature of the N-polar GaN layer in the short-wavelength violet multi-quantum well layer 540.

[0083] The multi-quantum-well emitting layer 500 is typically prepared by low-temperature deposition growth at 650℃-935℃. As the deposition thickness increases, the crystal quality and surface smoothness of the epitaxial film material deteriorate. Furthermore, the InGaN material in the quantum well layer with longer emission wavelengths has a relatively higher In content, leading to increased defects due to mismatch stress caused by well-barrier mismatch. Moreover, the growth temperature of high-In-content InGaN material is lower, further increasing defects in the grown epitaxial film. Therefore, the growth sequence of the multi-wavelength multi-quantum-well emitting layer 500 is designed to prioritize the deposition of long-wavelength quantum wells followed by short-wavelength quantum wells. The growth temperature of the InGaN material in the long-wavelength quantum wells is relatively lower than that of the short-wavelength quantum wells, and the growth temperature of the quantum barrier layer material should similarly be designed to match this. Using this invention, the multi-wavelength LED chip prepared with the multi-wavelength multi-quantum-well emitting layer 500 is more easily obtained, thereby improving the radiative recombination efficiency of the active region and further enhancing the luminous efficacy of the multi-wavelength LED chip.

[0084] For some specific implementation methods, please refer to Figures 2-6The long-wavelength blue light multi-quantum-well layer 510 has a periodic structure with 1-3 periods. Each period includes a first N-polarity pre-well insertion layer 511, a first Ga-polarity quantum well layer 512, a first N-polarity post-well insertion layer 513, and a first N-polarity quantum barrier layer 514, which are stacked sequentially. The first N-polarity pre-well insertion layer 511 includes In layers grown sequentially. x1 Ga 1-x1 N layer 5111, Al a1 Ga 1-a1 N layer 5112 and In y1 Ga 1-y1 N-layer 5113; the first Ga polar quantum well layer 512 is In z1 Ga 1-z1 N layers; the first N-polar well post-insertion layer 513 includes In layers grown sequentially. m1 Ga 1-m1 N layer 5131, Al b1 Ga 1-b1 The N-layer 5132 and the first undoped GaN layer 5133; the first N-polar quantum barrier layer 514 is the first N-polar GaN layer.

[0085] The short-wavelength blue light multi-quantum-well layer 520 has a periodic structure with 2-5 periods. Each period includes a second N-polarity pre-well insertion layer 521, a second Ga-polarity quantum well layer 522, a second N-polarity post-well insertion layer 523, and a second N-polarity quantum barrier layer 524, which are stacked sequentially. The second N-polarity pre-well insertion layer 521 includes In layers grown sequentially. x2 Ga 1-x2 N layer 5211, Al a2 Ga 1-a2 N-layer 5212 and In y2 Ga 1-y2 N layer 5213; the second Ga polar quantum well layer 522 is In z2 Ga 1-z2 N layers; the second N-polar well post-insertion layer 523 includes In layers grown sequentially. m2 Ga 1-m2 N layer 5231, Al b2 Ga 1-b2 The N-layer 5232 and the second undoped GaN layer 5233; the second N-polar quantum barrier layer 524 is a second N-polar GaN layer.

[0086] The long-wavelength violet multi-quantum-well layer 530 has a periodic structure with 2-5 periods. Each period includes a third N-polar well pre-insertion layer 531, a third Ga-polar quantum well layer 532, a third N-polar well post-insertion layer 533, and a third N-polar quantum barrier layer 534, which are stacked sequentially. The third N-polar well pre-insertion layer 531 comprises In layers grown sequentially. x3 Ga 1-x3 N layer 5311, Al a3 Ga 1-a3 N layer 5312 and In y3 Ga 1-y3 N-layer 5313; the third Ga polar quantum well layer 532 is In z3 Ga 1-z3 N layers; the third N-polar well post-insertion layer 533 comprises In layers grown sequentially. m3 Ga 1-m3 N layer 5331, Al b3 Ga 1-b3 The N-layer 5332 and the third undoped GaN layer 5333; the third N-polar quantum barrier layer 534 is a third N-polar GaN layer.

[0087] The short-wavelength violet quantum well layer 540 has a periodic structure with 1-3 periods. Each period includes a fourth N-polarity pre-well insertion layer 541, a fourth Ga-polarity quantum well layer 542, a fourth N-polarity post-well insertion layer 543, and a fourth N-polarity quantum barrier layer 544, stacked sequentially. The fourth N-polarity pre-well insertion layer 541 comprises In layers grown sequentially. x4 Ga 1-x4 N layer 5411, Al a4 Ga 1-a4 N layer 5412 and In y4 Ga 1-y4 N layer 5413; the fourth Ga polar quantum well layer 542 is In z4 Ga 1-z4 N layers; the fourth N-polar well post-insertion layer 543 comprises In layers grown sequentially. m4 Ga 1-m4 N layer 5431, Al b4 Ga 1-b4 The N-layer 5432 and the fourth undoped GaN layer 5433; the fourth N-polar quantum barrier layer 544 is a fourth N-polar GaN layer.

[0088] Preferably, the In x1 Ga 1-x1 The N-layer 5111 is either an N-type doped InGaN monolayer structure or an N-type doped InGaN multilayer structure, with a doping concentration of 1.16 × 10⁻⁶. 17 / cm 3-6.78×10 17 / cm 3 , 0≤x1≤0.025; the In x1 Ga 1-x1 The growth thickness of the N-layer 5111 is less than or equal to 0.38 nm, preferably 0.03 nm-0.38 nm; the In x2 Ga 1-x2 The N-layer 5211 is either an N-type doped InGaN monolayer structure or an N-type doped InGaN multilayer structure, with a doping concentration of 1.16 × 10⁻⁶. 17 / cm 3 -6.78×10 17 / cm 3 , 0≤x2≤0.025; the In x2 Ga 1-x2 The growth thickness of the N-layer 5211 is less than or equal to 0.38 nm, preferably 0.03 nm-0.38 nm; the In x3 Ga 1-x3 The N-layer 5311 is either an N-type doped InGaN monolayer structure or an N-type doped InGaN multilayer structure, with a doping concentration of 1.16 × 10⁻⁶. 17 / cm 3 -6.78×10 17 / cm 3 , 0≤x3≤0.025; the In x3 Ga 1-x3 The growth thickness of the N-layer 5311 is less than or equal to 0.38 nm, preferably 0.03 nm-0.38 nm; the In x4 Ga 1-x4 The N-layer 5411 is either an N-type doped InGaN monolayer structure or an N-type doped InGaN multilayer structure, with a doping concentration of 1.16 × 10⁻⁶. 17 / cm 3 -6.78×10 17 / cm 3 , 0≤x4≤0.025, the In x4 Ga 1-x4 The growth thickness of the N-layer 5411 is less than or equal to 0.38 nm, preferably 0.03 nm to 0.38 nm.

[0089] Understandably, the In x1 Ga 1-x1 N layer 5111, In x2 Ga 1-x2 N layer 5211, In x3 Ga 1-x3 N layer 5311, In x4 Ga 1-x4The N-layer 5411 can be entirely single-layer, entirely multi-layer, or partially single-layer and partially multi-layer. The doping concentrations can be equal or unequal. N-type doping elements include, but are not limited to, Si. x1, x2, x3, and x4 can be equal or unequal. The In... x1 Ga 1-x1 N layer 5111, In x2 Ga 1-x2 N layer 5211, In x3 Ga 1-x3 N layer 5311, In x4 Ga 1-x4 The growth thickness of the N-layer 5411 can be equal or unequal.

[0090] Preferably, the Al a1 Ga 1-a1 The N-layer 5112 is an undoped N-polar AlGaN layer, wherein the Al a1 Ga 1- a1 The growth thickness of the N-layer 5112 is less than or equal to 0.56 nm, preferably 0.03 nm-0.56 nm; the Al a2 Ga 1-a2 The N-layer 5212 is an undoped N-polar AlGaN layer, wherein the Al a2 Ga 1-a2 The growth thickness of the N-layer 5212 is less than or equal to 0.56 nm, preferably 0.03 nm-0.56 nm; the Al a3 Ga 1-a3 The N-layer 5312 is an undoped N-polar AlGaN layer, wherein the Al a3 Ga 1-a3 The growth thickness of the N-layer 5312 is less than or equal to 0.56 nm, preferably 0.03 nm-0.56 nm; the Al a4 Ga 1-a4 The N-layer 5412 is an undoped N-polar AlGaN layer, wherein the Al a4 Ga 1-a4 The growth thickness of the N-layer 5412 is less than or equal to 0.56 nm, preferably 0.03 nm to 0.56 nm.

[0091] Understandably, the Al a1 Ga 1-a1 N layer 5112, Al a2 Ga 1-a2 N layer 5212, Al a3 Ga 1-a3 N layer 5312, Al a4 Ga 1-a4The growth thickness of the N-layer 5412 can be equal or unequal.

[0092] Furthermore, a1≥a4, a4≥a2, a2≥a3, preferably a1>a4>a2>a3, so that the energy band barrier height of the barrier layer in the multi-quantum well light-emitting layer 500 is designed as a multi-layer structure of high barrier layer, medium barrier layer, low barrier layer and high barrier layer. This can bind the charge carrier electrons and holes in the multi-quantum well light-emitting layer 500, thereby improving the matching degree of electron and hole concentration in the multi-quantum well light-emitting layer 500, so as to further improve the luminous efficiency of the multi-band LED chip.

[0093] In some preferred embodiments, 0.05≤a1≤0.15, 0.02≤a2≤0.10, 0.01≤a3≤0.08, and 0.03≤a4≤0.12.

[0094] Preferably, the In y1 Ga 1-y1 The N-layer 5113 is an undoped N-polar InGaN layer, wherein the In... y1 Ga 1- y1 The growth thickness of the N-layer 5113 is less than or equal to 0.75 nm, preferably 0.03 nm-0.75 nm; the In y2 Ga 1-y2 The N-layer 5213 is an undoped N-polar InGaN layer, wherein the In... y2 Ga 1-y2 The growth thickness of the N-layer 5213 is less than or equal to 0.75 nm, preferably 0.03 nm-0.75 nm; the In y3 Ga 1-y3 The N-layer 5313 is an undoped N-polar InGaN layer, wherein the In... y3 Ga 1-y3 The growth thickness of the N-layer 5313 is less than or equal to 0.75 nm, preferably 0.03 nm-0.75 nm; the In y4 Ga 1-y4 The N-layer 5413 is an undoped N-polar InGaN layer, wherein the In... y4 Ga 1-y4 The growth thickness of the N-layer 5413 is less than or equal to 0.75 nm, preferably 0.03 nm to 0.75 nm. The In... y1 Ga 1-y1 N layer 5113, In y2 Ga 1-y2 N layer 5213, In y3 Ga 1-y3 N layer 5313, In y4 Ga 1-y4The growth thickness of the N-layer 5413 can be equal or unequal.

[0095] Furthermore, the In y1 Ga 1-y1 In layer N 5113, the proportion of In component y1 increases with increasing growth thickness; the In y2 Ga 1-y2 In layer N 5213, the proportion of In component y2 increases with increasing growth thickness; the In y3 Ga 1-y3 In layer N 5313, the proportion of In component y3 increases with increasing growth thickness. y4 Ga 1-y4 In layer N 5413, the proportion of In component y4 increases with increasing growth thickness. The In... y Ga 1-y The N-layer is an N-polar InGaN material with increasing In composition from bottom to top. It can improve the band barrier difference between the low-barrier InGaN material and the high-barrier AlGaN material in the multi-quantum-well emitting region, improve the quantum well's ability to bind charge carriers, reduce the electron overflow phenomenon in the multi-quantum-well emitting layer 500, and improve the radiative recombination efficiency in the multi-quantum-well emitting layer 500.

[0096] In some preferred embodiments, the In y1 Ga 1-y1 In layer N 5113, the proportion of In component y1 increases from 0 ≤ y1 ≤ 0.10 to 0.15 ≤ y1 ≤ 0.19 with increasing growth thickness; the In y2 Ga 1-y2 In layer N 5213, the proportion of In component y2 increases from 0 ≤ y2 ≤ 0.08 to 0.13 ≤ y2 ≤ 0.17 with increasing growth thickness; the In y3 Ga 1-y3 In layer N (5313), the proportion of In component y3 increases from 0 ≤ y3 ≤ 0.06 to 0.11 ≤ y3 ≤ 0.15 with increasing growth thickness; the In y4 Ga 1-y4 In the N-layer 5413, the proportion of In component y4 increases from 0≤y4≤0.05 to 0.09≤y4≤0.12 with the increase of growth thickness.

[0097] Preferably, the In z1 Ga 1-z1 The N-layer is an InGaN layer that is not intentionally doped. z1 Ga 1-z1 The N-layer has a growth thickness of 2.1 nm to 4.8 nm; the In z2 Ga 1-z2The N-layer is an InGaN layer that is not intentionally doped. z2 Ga 1-z2 The N-layer has a growth thickness of 2.1 nm to 4.8 nm; the In z3 Ga 1-z3 The N-layer is an InGaN layer that is not intentionally doped. z3 Ga 1-z3 The N-layer has a growth thickness of 2.1 nm to 4.8 nm; the In z4 Ga 1-z4 The N-layer is an InGaN layer that is not intentionally doped. z4 Ga 1-z4 The growth thickness of the N layer is 2.1 nm to 4.8 nm.

[0098] Understandably, the In z1 Ga 1-z1 N-layer, In z2 Ga 1-z2 N-layer, In z3 Ga 1-z3 N-layer, In z4 Ga 1-z4 The growth thickness of the N layers can be equal or unequal.

[0099] Furthermore, the In composition gradually decreases from long-wavelength to short-wavelength quantum wells, with z1 > z2 > z3 > z4. This helps to gradually release stress in the multilayer structure, avoiding crystal quality degradation caused by abrupt interface changes. Moreover, the gradient distribution of In composition ensures that each quantum well layer emits light of different wavelengths, ultimately forming the target white light emission through mixing. This also prevents excessive concentration of charge carriers in any one type of quantum well, thus balancing the emission contribution of each wavelength. In addition, matching the tolerance of different wavelengths to polarization effects can also prevent a sharp drop in efficiency in violet light wells due to excessively strong electric fields.

[0100] In some preferred embodiments, 0.17≤z1≤0.19, 0.15≤z2≤0.17, 0.12≤z3≤0.15, and 0.09≤z4≤0.12.

[0101] Preferably, the In m1 Ga 1-m1 The N-layer 5131 is an undoped N-polar InGaN layer, wherein the In... m1 Ga 1- m1 The growth thickness of the N-layer 5131 is less than or equal to 0.75 nm, preferably 0.03 nm-0.75 nm; the In m2 Ga 1-m2 The N-layer 5231 is an undoped N-polar InGaN layer, wherein the In... m2Ga 1-m2 The growth thickness of the N-layer 5231 is less than or equal to 0.75 nm, preferably 0.03 nm-0.75 nm; the In m3 Ga 1-m3 The N-layer 5331 is an undoped N-polar InGaN layer, wherein the In... m3 Ga 1-m3 The growth thickness of the N-layer 5331 is less than or equal to 0.75 nm, preferably 0.03 nm-0.75 nm; the In m4 Ga 1-m4 The N-layer 5431 is an undoped N-polar InGaN layer, wherein the In... m4 Ga 1-m4 The growth thickness of the N-layer 5431 is less than or equal to 0.75 nm, preferably 0.03 nm to 0.75 nm.

[0102] Understandably, the In m1 Ga 1-m1 N layer 5131, In m2 Ga 1-m2 N layer 5231, In m3 Ga 1-m3 N layer 5331, In m4 Ga 1-m4 The growth thickness of the N-layer 5431 can be equal or unequal.

[0103] Furthermore, the In m1 Ga 1-m1 In layer N 5131, the proportion of In component m1 decreases with increasing growth thickness; the In m2 Ga 1-m2 In layer N 5231, the proportion of In component m2 decreases with increasing growth thickness; the In m3 Ga 1-m3 In layer N 5331, the proportion of In component m3 decreases with increasing growth thickness; the In m4 Ga 1-m4 In the N-layer 5431, the proportion of In component m4 decreases with increasing growth thickness. In the In-inserted layer after the N-polar well. m Ga 1-m The N-layer is an N-polar InGaN material with an In composition decreasing from bottom to top, combined with an In composition increasing from bottom to top. y Ga 1-yThe N-layer further enhances the band barrier difference between the low-barrier InGaN and high-barrier AlGaN materials in the multi-quantum-well light-emitting layer 500, significantly improving the quantum well's ability to confine charge carriers, reducing electron overflow in the multi-quantum-well light-emitting layer 500, increasing the radiative recombination efficiency in the multi-quantum-well light-emitting layer 500, and ultimately improving the yield and brightness of multi-band LED chips.

[0104] In some preferred embodiments, the In m1 Ga 1-m1 In layer N 5131, the proportion of In component m1 decreases from 0.15≤m1≤0.19 to 0≤m1≤0.10 with increasing growth thickness; the In m2 Ga 1-m2 In layer N 5231, the proportion of In component m2 decreases from 0.13≤m2≤0.17 to 0≤m2≤0.08 with increasing growth thickness; the In m3 Ga 1-m3 In layer N (5331), the proportion of In component (m3) decreases from 0.11 ≤ m3 ≤ 0.15 to 0 ≤ m3 ≤ 0.06 with increasing growth thickness; the In... m4 Ga 1-m4 In the N-layer 5431, the proportion of In component m4 decreases from 0.09≤m4≤0.12 to 0≤m4≤0.05 as the growth thickness increases.

[0105] Preferably, the Al b1 Ga 1-b1 The N-layer 5132 is an undoped N-polar AlGaN layer, wherein the Al b1 Ga 1- b1 The growth thickness of the N-layer 5132 is less than or equal to 0.56 nm, preferably 0.03 nm-0.56 nm; the Al b2 Ga 1-b2 The N-layer 5232 is an undoped N-polar AlGaN layer, wherein the Al b2 Ga 1-b2 The growth thickness of the N-layer 5232 is less than or equal to 0.56 nm, preferably 0.03 nm-0.56 nm; the Al b3 Ga 1-b3 The N-layer 5332 is an undoped N-polar AlGaN layer, wherein the Al b3 Ga 1-b3 The growth thickness of the N-layer 5332 is less than or equal to 0.56 nm, preferably 0.03 nm-0.56 nm; the Al b4 Ga 1-b4 The N-layer 5432 is an undoped N-polar AlGaN layer with 0.01 ≤ b ≤ 0.12.b4 Ga 1-b4 The growth thickness of the N-layer 5432 is less than or equal to 0.56 nm, preferably 0.03 nm to 0.56 nm.

[0106] Understandably, the Al b1 Ga 1-b1 N layer 5132, Al b2 Ga 1-b2 N layer 5232, Al b3 Ga 1-b3 N layer 5332, Al b4 Ga 1-b4 The growth thickness of the N-layer 5432 can be equal or unequal.

[0107] Furthermore, a1≥b1, a2≥b2, a3≥b3, a4≥b4, and b1≥a4, b4≥a2, b2≥a3, Al a Ga 1-a In the N-layer, a high Al composition can form a higher conduction band barrier, effectively preventing electrons from leaking from the quantum well to the N-type region, thereby enhancing the localization of electrons in the quantum well. b Ga 1-b The lower Al content in the N-layer can reduce the valence band barrier height, reduce the obstruction of holes, and improve the injection efficiency of holes from the P-type region into the quantum well.

[0108] Furthermore, b1≥b4, b4≥b2, b2≥b3, preferably b1>b4>b2>b3. Based on this design, combined with the aforementioned Al... a Ga 1-a In the N-layer, a1 > a4 > a2 > a3, which further promotes the formation of a multilayer structure of high barrier layer - medium barrier layer - low barrier layer - high barrier layer. The barrier layer design of this structure and process can effectively bind carrier electrons and holes in the multi-quantum well light-emitting layer 500, thereby improving the matching degree of electron and hole concentration in the multi-quantum well light-emitting layer 500, so as to further improve the luminous efficiency of multi-band LED chips.

[0109] In some preferred embodiments, 0.03≤b1≤0.12, 0.01≤b2≤0.08, 0≤b3≤0.07, and 0.02≤b4≤0.10.

[0110] Preferably, the first undoped GaN layer 5133 is an undoped N-polar GaN monolayer structure or an undoped N-polar GaN multilayer structure, and the growth thickness of the first undoped GaN layer 5133 is less than or equal to 0.38 nm, preferably 0.03 nm to 0.38 nm; the second undoped GaN layer 5233 is an undoped N-polar GaN monolayer structure or an undoped N-polar GaN multilayer structure, and the growth thickness of the second undoped GaN layer 5233 is less than or equal to 0.38 nm, preferably 0.03 nm to 0.38 nm. m; the third undoped GaN layer 5333 is an undoped N-polar GaN monolayer structure or an undoped N-polar GaN multilayer structure, and the growth thickness of the third undoped GaN layer 5333 is less than or equal to 0.38 nm, preferably 0.03 nm-0.38 nm; the fourth undoped GaN layer 5433 is an undoped N-polar GaN monolayer structure or an undoped N-polar GaN multilayer structure, and the growth thickness of the fourth undoped GaN layer 5433 is less than or equal to 0.38 nm, preferably 0.03 nm-0.38 nm.

[0111] It is understandable that the first undoped GaN layer 5133, the second undoped GaN layer 5233, the third undoped GaN layer 5333, and the fourth undoped GaN layer 5433 can all be undoped N-polar GaN monolayer structures, or they can all be undoped N-polar GaN multilayer structures, or they can be partially undoped N-polar GaN monolayer structures and partially undoped N-polar GaN multilayer structures. The growth thickness of the first undoped GaN layer 5133, the second undoped GaN layer 5233, the third undoped GaN layer 5333, and the fourth undoped GaN layer 5433 can be equal or unequal.

[0112] Preferably, the first N-polar GaN layer is an N-type doped GaN monolayer structure or an N-type doped GaN multilayer structure, with a doping concentration of 2.1 × 10⁻⁶. 17 / cm 3 -8.7×10 17 / cm 3 The first N-polar GaN layer has a growth thickness of 6.2 nm to 13.9 nm; the second N-polar GaN layer is an N-type doped GaN monolayer structure or an N-type doped GaN multilayer structure, with a doping concentration of 2.1 × 10⁻⁶. 17 / cm 3 -8.7×10 17 / cm 3The second N-polar GaN layer has a growth thickness of 6.2 nm to 13.9 nm; the third N-polar GaN layer is an N-type doped GaN monolayer structure or an N-type doped GaN multilayer structure, with a doping concentration of 2.1 × 10⁻⁶. 17 / cm 3 -8.7×10 17 / cm 3 The third N-polar GaN layer has a growth thickness of 6.2 nm to 13.9 nm; the fourth N-polar GaN layer is an N-type doped GaN monolayer structure or an N-type doped GaN multilayer structure, with a doping concentration of 2.1 × 10⁻⁶. 17 / cm 3 -8.7×10 17 / cm 3 The growth thickness of the fourth N-polar GaN layer is 6.2 nm to 13.9 nm.

[0113] Understandably, the first, second, third, and fourth N-polar GaN layers can all be N-type doped N-polar GaN monolayer structures, or they can all be N-type doped N-polar GaN multilayer structures, or they can be partially N-type doped N-polar GaN monolayer structures and partially N-type doped N-polar GaN multilayer structures. The doping concentrations can be equal or unequal. The growth thicknesses of the first, second, third, and fourth N-polar GaN layers can be equal or unequal.

[0114] Accordingly, the present invention also provides a method for fabricating the aforementioned multi-band LED epitaxial structure, comprising the following steps:

[0115] (1) Provide a substrate 100;

[0116] (2) A buffer layer 200 is grown on the substrate 100;

[0117] (3) An N-type semiconductor layer 300 is grown on the buffer layer 200;

[0118] (4) A low-temperature stress relief layer 400 is grown on the N-type semiconductor layer 300;

[0119] (5) A multi-quantum well light-emitting layer 500 is grown on the low-temperature stress relief layer 400, wherein the multi-quantum well light-emitting layer 500 comprises a long-wavelength blue light multi-quantum well layer 510, a short-wavelength blue light multi-quantum well layer 520, a long-wavelength violet light multi-quantum well layer 530 and a short-wavelength violet light quantum well layer 540 stacked sequentially.

[0120] (6) An electron blocking layer 600 is grown on the multi-quantum-well light-emitting layer 500;

[0121] (7) A P-type semiconductor layer 700 is grown on the electron blocking layer 600;

[0122] Preferably, in step (5), growing a multi-quantum-well light-emitting layer 500 on the low-temperature stress-relieving layer 400 includes the following steps:

[0123] The obtained epitaxial material layer is annealed, and then an N-polar pre-well insertion layer is grown on the obtained epitaxial material layer; a Ga polar quantum well layer is grown on the N-polar pre-well insertion layer, and the obtained epitaxial material layer is annealed; an N-polar post-well insertion layer is grown on the annealed Ga polar quantum well layer; and an N-polar quantum barrier layer is grown on the N-polar post-well insertion layer.

[0124] In this application, before depositing and growing the N-polar well pre-insertion layer and the N-polar well post-insertion layer, the obtained epitaxial material layer is annealed. The surface of the epitaxial material layer after annealing will form a rough N-polar surface, which is beneficial to the subsequent deposition and growth of epitaxial materials for the N-polar well pre-insertion layer and the N-polar well post-insertion layer. At the same time, the rough N-polar surface can reduce the in-plane total internal reflection of photons and the light absorption loss in the multi-quantum well light-emitting layer 500, which is more conducive to light extraction and improves the light extraction efficiency, thereby improving the luminous efficacy of the multi-band LED chip.

[0125] Furthermore, the annealing process includes: holding the resulting epitaxial material layer in full NH3 for 8s-200s, wherein the annealing temperature is 820℃-1100℃ and the pressure is 50torr-600torr.

[0126] Furthermore, the growth temperature of the first N-polar GaN layer is T1, the growth temperature of the second N-polar GaN layer is T2, the growth temperature of the third N-polar GaN layer is T3, and the growth temperature of the fourth N-polar GaN layer is T4, satisfying: T1≤T2, T2≤T3, T3≤T4.

[0127] In some specific and preferred embodiments, step (5) specifically includes the following steps:

[0128] (51) Growth of long-wavelength blue light multi-quantum well layer 510;

[0129] This step specifically includes the following steps:

[0130] (511) The epitaxial material layer obtained in step (4) is annealed in all NH3;

[0131] (512) Sequential deposition and growth of In x1 Ga 1-x1 N layer 5111, Al a1 Ga 1-a1N layer 5112 and In y1 Ga 1-y1 N layers 5113 are used to obtain the first N-polarity well pre-insertion layer 511;

[0132] Optionally, the In x1 Ga 1-x1 The growth temperature of the N-layer 5111 is 750℃-928℃, and the growth pressure is 30 torr-360 torr; the Al a1 Ga 1-a1 The growth temperature of the N-layer 5112 is 780℃-928℃, and the growth pressure is 30 torr-360 torr; the In y1 Ga 1-y1 The growth temperature of the N-layer 5113 is 730℃-910℃, and the growth pressure is 30 torr-360 torr.

[0133] (513) Sedimentary growth In z1 Ga 1-z1 N layers were formed to obtain the first Ga polar quantum well layer 512, which was then annealed in all NH3.

[0134] Optionally, the In z1 Ga 1-z1 The growth temperature of the N layer is 735℃-928℃, and the pressure is 50 torr-360 torr.

[0135] (514) Sequential deposition and growth of In m1 Ga 1-m1 N layer 5131, Al b1 Ga 1-b1 An N-layer 5132 and a first undoped GaN layer 5133 are formed to obtain a first N-polar well followed by an insertion layer 513;

[0136] Optionally, the In m1 Ga 1-m1 The growth temperature of the N-layer 5131 is 730℃-910℃, and the growth pressure is 30 torr-360 torr; the Al b1 Ga 1-b1 The growth temperature of the N-layer 5132 is 780℃-928℃, and the growth pressure is 30 torr-360 torr; the growth temperature of the first undoped GaN layer 5133 is 800℃-928℃, and the growth pressure is 30 torr-360 torr.

[0137] (515) Deposit and grow the first N-polar GaN layer to obtain the first N-polar quantum barrier layer 514;

[0138] The growth temperature T1 of the first N-polar GaN layer is 805℃-916℃, and the growth pressure is 30 torr-360 torr.

[0139] (516) Repeat steps (511)-(515) above according to the preset number of alternating cycles to grow a long-wavelength blue light multi-quantum well layer 510 with a periodic structure.

[0140] Understandably, when repeating the above steps according to the preset number of alternating cycles, the epitaxial material layer obtained by deposition and growth for a certain period of time is annealed.

[0141] (52) Growth of short-wavelength blue light multi-quantum well layer 520;

[0142] The specific operations in this step are basically the same as in step (51), but it is necessary to modify the In... z2 Ga 1-z2 The growth conditions for the N-layer and the second N-polar GaN layer were adjusted, specifically...

[0143] The In z2 Ga 1-z2 The growth temperature of the N-layer is 750℃-928℃, and the pressure is 50 torr-360 torr; the growth temperature T2 of the second N-polar GaN layer is 815℃-926℃, and the growth pressure is 30 torr-360 torr.

[0144] (53) Growth of long-wavelength violet light multi-quantum well layer 530;

[0145] The specific operations in this step are basically the same as in step (51), but it is necessary to modify the In... z3 Ga 1-z3 The growth conditions for the N-layer and the third N-polar GaN layer were adjusted, specifically,

[0146] The In z3 Ga 1-z3 The growth temperature of the N-layer is 765℃-928℃, and the pressure is 50 torr-360 torr; the growth temperature T3 of the third N-polar GaN layer is 825℃-936℃, and the growth pressure is 30 torr-360 torr.

[0147] (54) Growth of short-wavelength violet quantum well layer 540;

[0148] The specific operations in this step are basically the same as in step (51), but it is necessary to modify the In... z4 Ga 1-z4 The growth conditions for the N-layer and the fourth N-polar GaN layer were adjusted, specifically,

[0149] The In z4Ga 1-z4 The growth temperature of the N layer is 780℃-928℃, and the pressure is 50 torr-360 torr; the growth temperature T4 of the fourth N-polar GaN layer is 835℃-950℃, and the growth pressure is 30 torr-360 torr.

[0150] It is understood that the substrate 100 can be a sapphire substrate, a silicon carbide substrate, or a silicon substrate; the buffer layer 200, the N-type semiconductor layer 300, the low-temperature stress relief layer 400, the electron blocking layer 600, and the P-type semiconductor layer 700 are all grown using existing processes and materials, and will not be further described in this embodiment.

[0151] The present invention will be further described below with reference to specific embodiments:

[0152] Example 1

[0153] This embodiment provides a multi-band LED epitaxial structure, comprising a substrate, a buffer layer, an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum-well light-emitting layer, an electron blocking layer, and a P-type semiconductor layer stacked sequentially. The multi-quantum-well light-emitting layer includes a long-wavelength blue light multi-quantum-well layer, a short-wavelength blue light multi-quantum-well layer, a long-wavelength violet light multi-quantum-well layer, and a short-wavelength violet light quantum-well layer stacked sequentially.

[0154] The long-wavelength blue light multi-quantum-well layer has a periodic structure. Each period includes a first N-polarity pre-well insertion layer, a first Ga-polarity quantum well layer, a first N-polarity post-well insertion layer, and a first N-polarity quantum barrier layer, stacked sequentially. The number of periods is 2, and λ1 is 468 nm.

[0155] The first N-polar well pre-insertion layer comprises In layers grown sequentially. x1 Ga 1-x1 N layer, Al a1 Ga 1-a1 N layers and In y1 Ga 1-y1 N layers, specifically, the In x1 Ga 1-x1 The N-layer is an N-type doped InGaN monolayer structure with a doping concentration of 4 × 10⁻⁶. 17 / cm 3 x1=0.12, and the growth thickness is 0.3nm; the Al a1 Ga 1-a1 The N-layer is an undoped N-polar AlGaN layer with a growth thickness of 0.45 nm and a1 = 0.1; the In... y1 Ga 1-y1 The N-layer is an undoped N-polar InGaN layer with a growth thickness of 0.65 nm and y1 = 0.05.

[0156] The first Ga polar quantum well layer is In z1 Ga 1-z1 N layers, the In z1 Ga 1-z1 The N layer is an InGaN layer without intentional doping, with a growth thickness of 3.5 nm and z1=0.17;

[0157] The first N-polar well post-insertion layer comprises In layers grown sequentially. m1 Ga 1-m1 N layer, Al b1 Ga 1-b1 The N-layer and the first undoped GaN layer, specifically, the In m1 Ga 1-m1 The N-layer is an undoped N-polar InGaN layer with a growth thickness of 0.65 nm and m1 = 0.15; the Al b1 Ga 1-b1 The N-layer is an undoped N-polar AlGaN layer with a growth thickness of 0.46 nm and b1 = 0.1; the first undoped GaN layer is an undoped N-polar GaN monolayer structure with a growth thickness of 0.3 nm.

[0158] The first N-polar quantum barrier layer is a first N-polar GaN layer, which is an N-type doped GaN monolayer structure with a doping concentration of 5.4 × 10⁻⁶. 17 / cm 3 The growth thickness is 10.1 nm.

[0159] The short-wavelength blue light multi-quantum-well layer has a periodic structure. Each period includes a second N-polarity pre-insertion layer, a second Ga-polarity quantum well layer, a second N-polarity post-insertion layer, and a second N-polarity quantum barrier layer, stacked sequentially. The number of periods is 3, and λ2 is 452 nm.

[0160] The second N-polar well pre-insertion layer comprises In layers grown sequentially. x2 Ga 1-x2 N layer, Al a2 Ga 1-a2 N layers and In y2 Ga 1-y2 N layers; the In x2 Ga 1-x2 The N-layer is an N-type doped InGaN monolayer structure with a doping concentration of 4 × 10⁻⁶. 17 / cm 3 x2=0.12, and the growth thickness is 0.3nm; the Al a2 Ga 1-a2The N-layer is an undoped N-polar AlGaN layer with a growth thickness of 0.45 nm and a2 = 0.1; the In... y2 Ga 1-y2 The N-layer is an undoped N-polar InGaN layer with a growth thickness of 0.65 nm and y2 = 0.05.

[0161] The second Ga polar quantum well layer is In z2 Ga 1-z2 N layers, the In z2 Ga 1-z2 The N layer is an InGaN layer without intentional doping, with a growth thickness of 3.5 nm and z2=0.15;

[0162] The second N-polar well post-insertion layer comprises In layers grown sequentially. m2 Ga 1-m2 N layer, Al b2 Ga 1-b2 The N-layer and the second undoped GaN layer, specifically, the In m2 Ga 1-m2 The N-layer is an undoped N-polar InGaN layer with a growth thickness of 0.65 nm and m² = 0.15; the Al b2 Ga 1-b2 The N-layer is an undoped N-polar AlGaN layer with a growth thickness of 0.46 nm and b2=0.1; the second undoped GaN layer is an undoped N-polar GaN monolayer structure with a growth thickness of 0.3 nm.

[0163] The second N-polar quantum barrier layer is a second N-polar GaN layer, which is an N-type doped GaN monolayer structure with a doping concentration of 5.4 × 10⁻⁶. 17 / cm 3 The growth thickness is 10.1 nm.

[0164] The long-wavelength violet multi-quantum-well layer has a periodic structure, with each period consisting of a third N-polar well pre-insertion layer, a third Ga-polar quantum well layer, a third N-polar well post-insertion layer, and a third N-polar quantum barrier layer stacked sequentially. The number of periods is 4, and λ3 is 440 nm.

[0165] The third N-polar well pre-insertion layer comprises In layers grown sequentially. x3 Ga 1-x3 N layer, Al a3 Ga 1-a3 N layers and In y3 Ga 1-y3 N layers, specifically, the In x3 Ga 1-x3The N-layer is an N-type doped InGaN monolayer structure with a doping concentration of 4 × 10⁻⁶. 17 / cm 3 x3=0.12, and the growth thickness is 0.3nm; the Al a3 Ga 1-a3 The N-layer is an undoped N-polar AlGaN layer with a growth thickness of 0.45 nm and a3 = 0.1; the In... y3 Ga 1-y3 The N-layer is an undoped N-polar InGaN layer with a growth thickness of 0.65 nm and y3 = 0.05.

[0166] The third Ga polar quantum well layer is In. z3 Ga 1-z3 N layers, the In z3 Ga 1-z3 The N layer is an InGaN layer without intentional doping, with a growth thickness of 3.5 nm and z3=0.13;

[0167] The third N-polar well post-insertion layer comprises In layers grown sequentially. m3 Ga 1-m3 N layer, Al b3 Ga 1-b3 The N-layer and the third undoped GaN layer, specifically, the In m3 Ga 1-m3 The N-layer is an undoped N-polar InGaN layer with a growth thickness of 0.65 nm and m³ = 0.15; the Al b3 Ga 1-b3 The N-layer is an undoped N-polar AlGaN layer with a growth thickness of 0.46 nm and b3 = 0.1; the third undoped GaN layer is an undoped N-polar GaN monolayer structure with a growth thickness of 0.3 nm.

[0168] The third N-polar quantum barrier layer is a third N-polar GaN layer, which is an N-type doped GaN monolayer structure with a doping concentration of 5.4 × 10⁻⁶. 17 / cm 3 The growth thickness is 10.1 nm.

[0169] The short-wavelength violet quantum well layer has a periodic structure, with each period consisting of a fourth N-polar well pre-insertion layer, a fourth Ga-polar quantum well layer, a fourth N-polar well post-insertion layer, and a fourth N-polar quantum barrier layer stacked sequentially. The number of periods is 2, and λ4 is 426 nm.

[0170] The fourth N-polar well pre-insertion layer comprises In layers grown sequentially. x4 Ga 1-x4 N layer, Ala4 Ga 1-a4 N layers and In y4 Ga 1-y4 N layers; the In x4 Ga 1-x4 The N-layer is an N-type doped InGaN monolayer structure with a doping concentration of 4 × 10⁻⁶. 17 / cm 3 x4=0.12, and the growth thickness is 0.3nm; the Al a4 Ga 1-a4 The N-layer is an undoped N-polar AlGaN layer with a growth thickness of 0.45 nm and a4 = 0.1; the In... y4 Ga 1-y4 N represents an undoped N-polar InGaN layer with a growth thickness of 0.65 nm and y4 = 0.05.

[0171] The fourth Ga polar quantum well layer is In. z4 Ga 1-z4 N layers, the In z4 Ga 1-z4 N represents an InGaN layer without intentional doping, with a growth thickness of 3.5 nm and z4 = 0.10;

[0172] The fourth N-polar well post-insertion layer comprises In layers grown sequentially. m4 Ga 1-m4 N layer, Al b4 Ga 1-b4 The N-layer and the fourth undoped GaN layer, specifically, the In m4 Ga 1-m4 The N-layer is an undoped N-polar InGaN layer with a growth thickness of 0.65 nm and m4 = 0.15; the Al b4 Ga 1-b4 The N-layer is an undoped N-polar AlGaN layer with a growth thickness of 0.46 nm and b4 = 0.1; the fourth undoped GaN layer is an undoped N-polar GaN monolayer structure with a growth thickness of 0.3 nm.

[0173] The fourth N-polar quantum barrier layer is a fourth N-polar GaN layer, which is an N-type doped GaN monolayer structure with a doping concentration of 5.4 × 10⁻⁶. 17 / cm 3 The growth thickness is 10.1 nm.

[0174] Accordingly, this embodiment also provides a method for fabricating the multi-band LED epitaxial structure, comprising the following steps:

[0175] (1) Provide a substrate;

[0176] (2) A buffer layer is grown on the substrate;

[0177] (3) An N-type semiconductor layer is grown on the buffer layer;

[0178] (4) A low-temperature stress relief layer is grown on the N-type semiconductor layer;

[0179] (5) A multi-quantum well light-emitting layer is grown on the low-temperature stress relief layer, wherein the multi-quantum well light-emitting layer comprises a long-wavelength blue light multi-quantum well layer, a short-wavelength blue light multi-quantum well layer, a long-wavelength violet light multi-quantum well layer, and a short-wavelength violet light quantum well layer stacked sequentially.

[0180] (6) An electron blocking layer is grown on the multi-quantum-well light-emitting layer;

[0181] (7) A P-type semiconductor layer is grown on the electron blocking layer;

[0182] Specifically, step (5) includes the following steps:

[0183] (51) Growth of long-wavelength blue light multi-quantum well layers;

[0184] This step specifically includes the following steps:

[0185] (511) Sequential deposition and growth of In x1 Ga 1-x1 N layer, Al a1 Ga 1-a1 N layers and In y1 Ga 1-y1 N layers are obtained to form the first N-polarity well pre-insertion layer;

[0186] The In x1 Ga 1-x1 The growth temperature of the N layer is 840℃, and the growth pressure is 190 torr; the Al a1 Ga 1-a1 The growth temperature of the N layer is 850℃, and the growth pressure is 190 torr; the In... y1 Ga 1-y1 The growth temperature of the N layer is 820℃, and the growth pressure is 190 torr.

[0187] (512) Sedimentary growth In z1 Ga 1-z1 N layers are obtained to form the first Ga polar quantum well layer;

[0188] The In z1 Ga 1-z1 The growth temperature of the N layer is 820℃, and the growth pressure is 190 torr.

[0189] (513) Sequential deposition and growth of In m1 Ga 1-m1 N-layer In m1 Ga 1-m1 N layer, Al b1 Ga 1-b1 After forming an N-layer and a first undoped GaN layer, an insertion layer is formed to obtain the first N-polar well.

[0190] The In m1 Ga 1-m1 The growth temperature of the N layer is 820℃, and the growth pressure is 190 torr; the Al b1 Ga 1-b1 The growth temperature of the N layer is 855℃ and the growth pressure is 190 torr; the growth temperature of the first undoped GaN layer is 865℃ and the growth pressure is 190 torr.

[0191] (514) Deposit and grow the first N-polar GaN layer to obtain the first N-polar quantum barrier layer;

[0192] The growth temperature T1 of the first N-polar GaN layer is 875℃, and the growth pressure is 190 torr.

[0193] (515) Repeat steps (511)-(514) above according to the preset number of alternating cycles to grow a long-wavelength blue light multi-quantum well layer with a periodic structure.

[0194] (52) Growth of short-wavelength blue light multi-quantum well layers;

[0195] The specific operations in this step are basically the same as in step (51), except that:

[0196] The In z2 Ga 1-z2 The growth temperature of the N-layer is 840℃ and the pressure is 190 torr; the growth temperature T2 of the second N-polar GaN layer is 875℃ and the growth pressure is 190 torr.

[0197] (53) Growth of long-wavelength violet multi-quantum well layers;

[0198] The specific operations in this step are basically the same as in step (51), except that:

[0199] The In z3 Ga 1-z3 The growth temperature of the N-layer is 845℃ and the pressure is 190 torr; the growth temperature T3 of the third N-polar GaN layer is 875℃ and the growth pressure is 190 torr.

[0200] (54) Growth of short-wavelength violet quantum well layer;

[0201] The specific operations in this step are basically the same as in step (51), except that:

[0202] The In z4 Ga 1-z4 The growth temperature of the N layer is 855℃ and the pressure is 190 torr; the growth temperature T4 of the fourth N-polar GaN layer is 875℃ and the growth pressure is 190 torr.

[0203] Example 2

[0204] This embodiment provides a multi-band LED epitaxial structure, which is basically the same as that in Embodiment 1, except that:

[0205] In step (5), during each cycle of growing the long-wavelength blue light multi-quantum-well layer, the short-wavelength blue light multi-quantum-well layer, the long-wavelength violet light multi-quantum-well layer, and the short-wavelength violet light final quantum-well layer, before depositing the N-polar well pre-insertion layer and before depositing the N-polar well post-insertion layer, the resulting epitaxial material layer is annealed. That is:

[0206] Step (5) specifically includes the following steps:

[0207] (51) Growth of long-wavelength blue light multi-quantum well layers;

[0208] This step specifically includes the following steps:

[0209] (511) The epitaxial material layer obtained in step (4) is annealed in all NH3;

[0210] In this step, the epitaxial material layer obtained in step (4) is kept in NH3 for 110s, wherein the annealing temperature is 960℃ and the pressure is 280 torr.

[0211] (512) Sequential deposition and growth of In x1 Ga 1-x1 N layer, Al a1 Ga 1-a1 N layers and In y1 Ga 1-y1 N layers are obtained to form the first N-polarity well pre-insertion layer;

[0212] The In x1 Ga 1-x1 The growth temperature of the N layer is 840℃, and the growth pressure is 190 torr; the Al a1 Ga 1-a1 The growth temperature of the N layer is 850℃, and the growth pressure is 190 torr; the In... y1 Ga 1-y1 The growth temperature of the N layer is 820℃, and the growth pressure is 190 torr.

[0213] (513) Sedimentary growth In z1 Ga 1-z1 N layers were formed to obtain the first Ga polar quantum well layer, which was then annealed in all NH3.

[0214] The In z1 Ga 1-z1 The growth temperature of the N layer is 820℃ and the pressure is 190 torr; the annealing temperature is 960℃ and the pressure is 280 torr.

[0215] (514) Sequential deposition and growth of In m1 Ga 1-m1 N layer, Al b1 Ga 1-b1 After forming an N-layer and a first undoped GaN layer, an insertion layer is formed to obtain the first N-polar well.

[0216] The In m1 Ga 1-m1 The growth temperature of the N layer is 820℃, and the growth pressure is 190 torr; the Al b1 Ga 1-b1 The growth temperature of the N layer is 855℃ and the growth pressure is 190 torr; the growth temperature of the first undoped GaN layer is 865℃ and the growth pressure is 190 torr.

[0217] (515) Deposit and grow the first N-polar GaN layer to obtain the first N-polar quantum barrier layer;

[0218] The growth temperature T1 of the first N-polar GaN layer is 860℃, and the growth pressure is 190 torr.

[0219] (516) Repeat steps (511)-(515) according to the preset number of alternating cycles to grow a long-wavelength blue light multi-quantum well layer with a periodic structure. When repeating the above steps according to the preset number of alternating cycles, the epitaxial material layer obtained by depositing and growing for a certain period of time is annealed.

[0220] (52) Growth of short-wavelength blue light multi-quantum well layers;

[0221] (53) Growth of long-wavelength violet multi-quantum well layers;

[0222] (54) Growth of short-wavelength violet quantum well layer;

[0223] Example 3

[0224] This embodiment provides a multi-band LED epitaxial structure, which is basically the same as that in Embodiment 2, except that:

[0225] a1=0.11, a2=0.06, a3=0.03, a4=0.08;

[0226] b1=0.09, b2=0.03, b3=0.02, b4=0.06.

[0227] Example 4

[0228] This embodiment provides a multi-band LED epitaxial structure, which is basically the same as that in Embodiment 3, except that:

[0229] The proportion of In component y1 increases from 0.05 to 0.17 with increasing growth thickness; the proportion of In component y2 increases from 0.04 to 0.15 with increasing growth thickness; the proportion of In component y3 increases from 0.03 to 0.13 with increasing growth thickness; and the proportion of In component y4 increases from 0.02 to 0.11 with increasing growth thickness.

[0230] Example 5

[0231] This embodiment provides a multi-band LED epitaxial structure, which is basically the same as that in embodiment 4, except that:

[0232] The percentage of In component m1 decreases from 0.17 to 0.05 with increasing growth thickness; the percentage of In component m2 decreases from 0.15 to 0.04 with increasing growth thickness; the percentage of In component m3 decreases from 0.13 to 0.03 with increasing growth thickness; and the percentage of In component m4 decreases from 0.11 to 0.02 with increasing growth thickness.

[0233] Example 6

[0234] This embodiment provides a multi-band LED epitaxial structure, which is basically the same as that in Embodiment 5, except that:

[0235] The growth temperature T1 of the first N-polar GaN layer is 860℃, the growth temperature T2 of the second N-polar GaN layer is 870℃, the growth temperature T3 of the third N-polar GaN layer is 880℃, and the growth temperature T4 of the fourth N-polar GaN layer is 890℃.

[0236] Comparative Example 1

[0237] This comparative example provides a multi-band LED epitaxial structure, which is basically the same as that in Example 1, except that:

[0238] The multi-quantum well light-emitting layer is a blue multi-quantum well layer with an emission wavelength of 452nm.

[0239] The LED epitaxial structures prepared in Examples 1-6 and Comparative Example 1 were fabricated into 10mil×24mil chips using the same chip process conditions. 300 LED chips were sampled from each example and tested at a current of 120mA. The luminous efficiency improvement rate of each example was calculated compared with that of the LED chip prepared in Comparative Example 1. The specific test results are shown in Table 1.

[0240] Table 1. Test results of the examples and comparative examples

[0241]

[0242] As can be seen from the above results, after the multi-band LED epitaxial structure in this application forms an LED chip, it generates a full-spectrum white LED light source by exciting the red and green mixed phosphor layer with four wavelength light sources. The generated full-spectrum white light is closer to the solar spectrum, thereby realizing a healthy full-spectrum white LED light source with a high color rendering index, and can also improve the luminous efficiency of the multi-band LED chip.

[0243] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A multi-band LED epitaxial structure, characterized in that, It includes a substrate, a buffer layer, an N-type semiconductor layer, a low-temperature stress relief layer, a multi-quantum-well light-emitting layer, an electron-blocking layer, and a P-type semiconductor layer, which are stacked sequentially. The multi-quantum-well emitting layer comprises a long-wavelength blue multi-quantum-well layer, a short-wavelength blue multi-quantum-well layer, a long-wavelength violet multi-quantum-well layer, and a short-wavelength violet end-quantum-well layer stacked sequentially. The long-wavelength blue multi-quantum-well layer, the short-wavelength blue multi-quantum-well layer, the long-wavelength violet multi-quantum-well layer, and the short-wavelength violet end-quantum-well layer are all periodic structures. Each period includes an N-polar well pre-insertion layer, a Ga-polar quantum well layer, an N-polar well post-insertion layer, and an N-polar quantum barrier layer stacked sequentially. The N-polar well pre-insertion layer comprises In layers grown sequentially. x Ga 1-x N layer, Al a Ga 1-a N layers and In y Ga 1-y N layers; The Ga polar quantum well layer is In z Ga 1-z N layers; The N-polar well post-insertion layer comprises In layers grown sequentially. m Ga 1-m N layer, Al b Ga 1-b N-layer and undoped GaN layer; The N-polar quantum barrier layer is an N-polar GaN layer; The growth temperature of the N-polar GaN layer in the long-wavelength blue light multi-quantum well layer is less than or equal to the growth temperature of the N-polar GaN layer in the short-wavelength blue light multi-quantum well layer, the growth temperature of the N-polar GaN layer in the short-wavelength blue light multi-quantum well layer is less than or equal to the growth temperature of the N-polar GaN layer in the long-wavelength violet light multi-quantum well layer, and the growth temperature of the N-polar GaN layer in the long-wavelength violet light multi-quantum well layer is less than or equal to the growth temperature of the N-polar GaN layer in the short-wavelength violet light multi-quantum well layer.

2. The multi-band LED epitaxial structure as described in claim 1, characterized in that, The emission wavelength of the long-wavelength blue light multi-quantum well layer is λ1, the emission wavelength of the short-wavelength blue light multi-quantum well layer is λ2, the emission wavelength of the long-wavelength violet light multi-quantum well layer is λ3, and the emission wavelength of the short-wavelength violet light multi-quantum well layer is λ4, where λ1 > λ2 > λ3 > λ4.

3. The multi-band LED epitaxial structure as described in claim 1, characterized in that, The In x Ga 1-x The N-layer is either an N-type doped InGaN monolayer or an N-type doped InGaN multilayer structure, with a doping concentration of 1.16 × 10⁻⁶. 17 / cm 3 -6.78×10 17 / cm 3 , 0 < x ≤ 0.025; the In x Ga 1-x The growth thickness of the N layer is less than or equal to 0.38 nm; The Al a Ga 1-a The N-layer is an undoped N-polar AlGaN layer, with 0.01 ≤ a ≤ 0.

15. a Ga 1-a The growth thickness of the N layer is less than or equal to 0.56 nm; The In y Ga 1-y The N-layer is an undoped N-polar InGaN layer, where the In content (y) increases with increasing growth thickness, and 0 < y ≤ 0.

19. y Ga 1-y The growth thickness of the N layer is less than or equal to 0.75 nm; The In m Ga 1-m The N-layer is an undoped N-polar InGaN layer, where the In content m decreases with increasing growth thickness, 0 < m ≤ 0.19; the In... m Ga 1-m The growth thickness of the N layer is less than or equal to 0.75 nm; The Al b Ga 1-b The N-layer is an undoped N-polar AlGaN layer, where 0 < b ≤ 0.

12. b Ga 1-b The growth thickness of the N layer is less than or equal to 0.56 nm; The undoped GaN layer is either a single-layer N-polar GaN structure or a multilayer N-polar GaN structure without intentional doping, and the growth thickness of the undoped GaN layer is less than or equal to 0.38 nm.

4. The multi-band LED epitaxial structure as described in claim 1, characterized in that, The In z Ga 1-z The N layer is an InGaN layer that is not intentionally doped; the In z Ga 1-z The growth thickness of the N layer is 2.1 nm-4.8 nm; In long-wavelength blue light multi-quantum well layer z Ga 1-z The proportion of In component in the N layer is greater than that in the short-wavelength blue light multi-quantum-well layer. z Ga 1-z The In composition percentage of the N layer, and the In content of the short-wavelength blue light multi-quantum well layer. z Ga 1-z The proportion of In in the N-layer is greater than that in the long-wavelength violet light multi-quantum-well layer. z Ga 1-z The In composition percentage of the N-layer, and the In content of the long-wavelength violet multi-quantum well layer. z Ga 1-z The proportion of In component in the N layer is greater than that in the short-wavelength violet quantum well layer. z Ga 1-z The proportion of In component in the N layer.

5. The multi-band LED epitaxial structure as described in claim 1, characterized in that, The N-polar GaN layer is an N-type doped GaN layer with a doping concentration of 2.1 × 10⁻⁶. 17 / cm 3 -8.7×10 17 / cm 3 The thickness of the N-polar GaN layer is 6.2 nm to 13.9 nm.

6. The multi-band LED epitaxial structure as described in claim 1, characterized in that, The number of cycles of the long-wavelength blue light multi-quantum well layer is 1-3, and a single cycle includes a first N-polar well pre-insertion layer, a first Ga-polar quantum well layer, a first N-polar well post-insertion layer and a first N-polar quantum barrier layer stacked sequentially. The first N-polar well pre-insertion layer comprises In layers grown sequentially. x1 Ga 1-x1 N layer, Al a1 Ga 1-a1 N layers and In y1 Ga 1-y1 N layers; the first Ga polar quantum well layer is In. z1 Ga 1-z1 N layers; the first N-polar well post-insertion layer comprises In layers grown sequentially. m1 Ga 1-m1 N layer, Al b1 Ga 1-b1 The N-layer and the first undoped GaN layer; the first N-polar quantum barrier layer is the first N-polar GaN layer; The short-wavelength blue light multi-quantum well layer has 2-5 cycles, and each cycle includes a second N-polar well pre-insertion layer, a second Ga-polar quantum well layer, a second N-polar well post-insertion layer, and a second N-polar quantum barrier layer stacked sequentially. The second N-polar well pre-insertion layer comprises In layers grown sequentially. x2 Ga 1-x2 N layer, Al a2 Ga 1-a2 N layers and In y2 Ga 1-y2 N-layer; the second Ga polar quantum well layer is In. z2 Ga 1-z2 N layers; the second N-polar well post-insertion layer comprises In layers grown sequentially. m2 Ga 1-m2 N layer, Al b2 Ga 1-b2 The N-layer and the second undoped GaN layer; the second N-polar quantum barrier layer is a second N-polar GaN layer; The number of cycles of the long-wavelength violet multi-quantum well layer is 2-5, and a single cycle includes a third N-polar well pre-insertion layer, a third Ga-polar quantum well layer, a third N-polar well post-insertion layer and a third N-polar quantum barrier layer stacked sequentially. The third N-polar well pre-insertion layer comprises In layers grown sequentially. x3 Ga 1-x3 N layer, Al a3 Ga 1-a3 N layers and In y3 Ga 1-y3 N layers; the third Ga polar quantum well layer is In. z3 Ga 1-z3 N layers; the third N-polar well post-insertion layer comprises In layers grown sequentially. m3 Ga 1-m3 N layer, Al b3 Ga 1-b3 The N-layer and the third undoped GaN layer; the third N-polar quantum barrier layer is a third N-polar GaN layer; The number of cycles of the short-wavelength violet quantum well layer is 1-3, and a single cycle includes a fourth N-polar well pre-insertion layer, a fourth Ga-polar quantum well layer, a fourth N-polar well post-insertion layer and a fourth N-polar quantum barrier layer stacked sequentially. The fourth N-polar well pre-insertion layer comprises In layers grown sequentially. x4 Ga 1-x4 N layer, Al a4 Ga 1-a4 N layers and In y4 Ga 1-y4 N layers; the fourth Ga polar quantum well layer is In. z4 Ga 1-z4 N layers; the fourth N-polar well post-insertion layer comprises In layers grown sequentially. m4 Ga 1-m4 N layer, Al b4 Ga 1-b4 The N-layer and the fourth undoped GaN layer; the fourth N-polar quantum barrier layer is a fourth N-polar GaN layer.

7. The multi-band LED epitaxial structure as described in claim 6, characterized in that, z1>z2>z3>z4, and the growth temperature of the first N-polar GaN layer is T1, the growth temperature of the second N-polar GaN layer is T2, the growth temperature of the third N-polar GaN layer is T3, and the growth temperature of the fourth N-polar GaN layer is T4, satisfying: T1≤T2, T2≤T3, T3≤T4; a1≥b1, a2≥b2, a3≥b3, a4≥b4, and a1≥a4, a4≥a2, a2≥a3, b1≥b4, b4≥b2, b2≥b3; b1≥a4, b4≥a2, b2≥a3.

8. The multi-band LED epitaxial structure as described in claim 6 or 7, characterized in that, The In y1 Ga 1-y1 In layer N, the proportion of In component y1 increases from 0 < y1 ≤ 0.10 to 0.15 ≤ y1 ≤ 0.19 with increasing growth thickness. m1 Ga 1-m1 In the N layer, the proportion of In component m1 decreases from 0.15≤m1≤0.19 to 0<m1≤0.10 as the growth thickness increases; The In y2 Ga 1-y2 In layer N, the proportion of In component y2 increases from 0 < y2 ≤ 0.08 to 0.13 ≤ y2 ≤ 0.17 with increasing growth thickness. m2 Ga 1-m2 In the N layer, the proportion of In component m2 decreases from 0.13≤m2≤0.17 to 0<m2≤0.08 with the increase of growth thickness; The In y3 Ga 1-y3 In layer N, the proportion of In component y3 increases from 0 < y3 ≤ 0.06 to 0.11 ≤ y3 ≤ 0.15 with increasing growth thickness. m3 Ga 1-m3 In the N layer, the proportion of In component m3 decreases from 0.11≤m3≤0.15 to 0<m3≤0.06 with increasing growth thickness; The In y4 Ga 1-y4 In layer N, the proportion of In component y4 increases from 0 < y4 ≤ 0.05 to 0.09 ≤ y4 ≤ 0.12 with increasing growth thickness. m4 Ga 1-m4 In the N layer, the proportion of In component m4 decreases from 0.09≤m4≤0.12 to 0<m4≤0.05 as the growth thickness increases; 0.05≤a1≤0.15, 0.03≤b1≤0.12; 0.02≤a2≤0.10, 0.01≤b2≤0.08; 0.01≤a3≤0.08, 0<b3≤0.07; 0.03≤a4≤0.12, 0.02≤b4≤0.10; 0.17≤z1≤0.19, 0.15≤z2≤0.17, 0.12≤z3≤0.15, 0.09≤z4≤0.12; The growth temperature T1 of the first N-polar GaN layer is 805℃-916℃, and the growth pressure is 30 torr-360 torr; the growth temperature T2 of the second N-polar GaN layer is 815℃-926℃, and the growth pressure is 30 torr-360 torr; the growth temperature T3 of the third N-polar GaN layer is 825℃-936℃, and the growth pressure is 30 torr-360 torr; the growth temperature T4 of the fourth N-polar GaN layer is 835℃-950℃, and the growth pressure is 30 torr-360 torr.

9. A method for fabricating a multi-band LED epitaxial structure as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Provide a substrate; (2) A buffer layer is grown on the substrate; (3) An N-type semiconductor layer is grown on the buffer layer; (4) A low-temperature stress relief layer is grown on the N-type semiconductor layer; (5) A multi-quantum-well light-emitting layer is grown on the low-temperature stress-relieving layer; (6) An electron blocking layer is grown on the multi-quantum-well light-emitting layer; (7) A P-type semiconductor layer is grown on the electron blocking layer; The multi-quantum-well emitting layer comprises a long-wavelength blue multi-quantum-well layer, a short-wavelength blue multi-quantum-well layer, a long-wavelength violet multi-quantum-well layer, and a short-wavelength violet final quantum well layer, all stacked sequentially. Each of the long-wavelength blue multi-quantum-well layer, the short-wavelength blue multi-quantum-well layer, the long-wavelength violet multi-quantum-well layer, and the short-wavelength violet final quantum well layer is a periodic structure, and each period comprises a pre-insertion layer of an N-polarity well, a Ga-polarity quantum well layer, a post-insertion layer of an N-polarity well, and an N-polarity quantum barrier layer, all stacked sequentially. The N-polar well pre-insertion layer comprises In layers grown sequentially. x Ga 1-x N layer, Al a Ga 1-a N layers and In y Ga 1-y N layers; the Ga polar quantum well layer is In z Ga 1-z N layers; the N-polar well post-insertion layer comprises In layers grown sequentially. m Ga 1-m N layer, Al b Ga 1-b The N-layer is an undoped GaN layer; the N-polar quantum barrier layer is an N-polar GaN layer.

10. The method for fabricating a multi-band LED epitaxial structure as described in claim 9, characterized in that, In step (5), growing a multi-quantum-well light-emitting layer on the low-temperature stress-relieving layer includes the following steps: The obtained epitaxial material layer is annealed, and then an N-polar well pre-insertion layer is grown on the obtained epitaxial material layer. A Ga polar quantum well layer is grown on the N-polar well pre-insertion layer, and the resulting epitaxial material layer is annealed. An N-polar well is grown on the annealed Ga polar quantum well layer, followed by an insertion layer; An N-polar quantum barrier layer is grown on the N-polar well back insertion layer; The annealing process includes: the obtained epitaxial material layer is held in full NH3 for 8s-200s, wherein the annealing temperature is 820℃-1100℃ and the pressure is 50torr-600torr.

Images