Light emitting diode epitaxial wafer and light emitting diode

Abstract

The application discloses an epitaxial wafer of a light emitting diode and the light emitting diode, and relates to the field of photoelectric devices. The epitaxial wafer comprises a first multi-quantum well layer, a first hole injection enhancement layer, a second multi-quantum well layer, a second hole injection enhancement layer and a third multi-quantum well layer; the first multi-quantum well layer comprises an In x Ga 1‑x N layer and a first GaN layer, and the light emitting wavelength is λ1; the first hole injection enhancement layer comprises an In α Ga 1‑α N layer and an In a Al b Ga 1‑a‑b N layer; the second multi-quantum well layer comprises an In y Ga 1‑y N layer and a second GaN layer, and the light emitting wavelength is λ2; the second hole injection enhancement layer comprises an In β Ga 1‑β N layer and a third GaN layer; and the third multi-quantum well layer comprises an In z Ga 1‑z N layer and a fourth GaN layer, and the light emitting wavelength is λ3; α < β < x < y < z, α >= a, and λ1 < λ2 <= λ3. By implementing the application, the uniformity of light of each waveband and the light emitting efficiency can be improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic devices, and more particularly to a light-emitting diode epitaxial wafer and a light-emitting diode. Background Technology

[0002] Multi-band LED chips are a crucial tool for developing full-spectrum lighting. To achieve multi-band emission, multiple quantum well layers with different In compositions are designed in the active light-emitting region. For stable emission, these multi-quantum well layers with different compositions require a sufficiently high number of periods, resulting in a higher number of periods in the active light-emitting region compared to ordinary single-band LED chips. However, when using multi-quantum well layers with more periods, holes often struggle to effectively enter the lower light-emitting region near the N-type layer, leading to unstable emission in this region.

[0003] On the other hand, to improve the crystal quality of quantum well layers (InGaN material), quantum well layers with higher In content are typically used near the N-type layer and those with lower In content near the P-type layer, gradually increasing the growth temperature to improve crystal quality. However, further research by the inventors revealed that high-In-content InGaN layers have poor crystal quality, which often leads to amplification of defects propagating from the substrate, resulting in excessively strong polarization effects at the bottom layer and a significant reduction in the overlap of hole and electron wave functions. Consequently, the luminous efficiency of the multi-quantum well layer corresponding to that wavelength band is actually lower. Moreover, the multi-quantum well layer near the P-type layer has a small lattice mismatch and high electron-hole recombination efficiency in this region, which also leads to higher luminous efficiency in this region. This results in higher non-uniformity of light across different wavelength bands in the entire LED chip, making subsequent dimming more difficult. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a light-emitting diode epitaxial wafer that can realize multi-band light emission, and the light emission of each band is uniform and the light emission efficiency is high.

[0005] Another technical problem that the present invention needs to solve is to provide a light-emitting diode.

[0006] To address the aforementioned problems, this invention discloses a light-emitting diode epitaxial wafer, comprising a substrate, and an N-type semiconductor layer, a first multiple quantum well layer, a first hole injection enhancement layer, a second multiple quantum well layer, a second hole injection enhancement layer, a third multiple quantum well layer, and a P-type semiconductor layer sequentially stacked on the substrate.

[0007] The first multi-quantum-well layer has a periodic structure, and each period includes sequentially stacked In... x Ga 1-x The N-layer and the first GaN layer; the emission wavelength of the first multi-quantum-well layer is λ1;

[0008] The first hole injection enhancement layer has a periodic structure, and each period includes sequentially stacked In... α Ga 1-α N layers and In a Al b Ga 1-a-b N layers;

[0009] The second multiple quantum well layer has a periodic structure, with each period consisting of sequentially stacked In... y Ga 1-y The N-layer and the second GaN layer; the emission wavelength of the second multiple quantum well layer is λ2;

[0010] The second hole injection enhancement layer has a periodic structure, and each period includes sequentially stacked In... β Ga 1-β N-layer and third GaN layer;

[0011] The third multi-quantum well layer has a periodic structure, with each period consisting of sequentially stacked In... z Ga 1-z The N-layer and the fourth GaN layer; the emission wavelength of the third multi-quantum-well layer is λ3;

[0012] Among them, α<β<x<y<z, α≥a, λ1<λ2≤λ3.

[0013] As an improvement to the above technical solution, the number of cycles in the first multi-quantum well layer is ≥2, the number of cycles in the second multi-quantum well layer is ≥3, and the number of cycles in the third multi-quantum well layer is ≥2.

[0014] As an improvement to the above technical solution, the number of periods in the first multi-quantum well layer is 2 to 5; and / or

[0015] The In x Ga 1-x In layer N, the value of x ranges from 0.11 to 0.15, and its thickness is from 2 nm to 5 nm; and / or

[0016] The thickness of the first GaN layer is 8nm~18nm; and / or

[0017] The second multiple quantum well layer has a period number of 3 to 6; and / or

[0018] The In y Ga 1-y In layer N, the value of y ranges from 0.15 to 0.17, and its thickness is from 2 nm to 5 nm; and / or

[0019] The thickness of the second GaN layer is 7nm~18nm; and / or

[0020] The third multi-quantum well layer has a period number of 2 to 5; and / or

[0021] The In z Ga 1-z In layer N, the value of z ranges from 0.17 to 0.19, and its thickness is from 2 nm to 5 nm; and / or

[0022] The thickness of the fourth GaN layer is 6nm~18nm.

[0023] As an improvement to the above technical solution, the number of cycles of the first hole injection enhancement layer is 2 to 5; and / or

[0024] The In α Ga 1-α In layer N, the value of α ranges from 0.005 to 0.08, and its thickness is from 0.3 nm to 3 nm; and / or

[0025] The In a Al b Ga 1-a-b In layer N, the value of 'a' ranges from 0.005 to 0.065, the value of 'b' ranges from 0.02 to 0.2, and the thickness is 0.5 nm to 3 nm; and / or

[0026] The number of cycles in the second hole injection enhancement layer is 2 to 8; and / or

[0027] The In β Ga 1-β In layer N, the value of β ranges from 0.01 to 0.1, and its thickness ranges from 0.5 nm to 3 nm; and / or

[0028] The thickness of the third GaN layer is 0.5 nm to 3 nm.

[0029] As an improvement to the above technical solution, the In α Ga 1-α Mg is doped in the N layer, and the In β Ga 1-β Mg is doped in the N-layer;

[0030] The In β Ga 1-β The Mg doping concentration in the N layer is less than that in the In layer. α Ga 1-α Mg doping concentration in the N layer.

[0031] As an improvement to the above technical solution, the In α Ga 1-α The Mg doping concentration of the N layer is 3.2 × 10⁻⁶. 18 cm -3 ~5.6×10 19cm -3 ;

[0032] The In β Ga 1-β The Mg doping concentration of the N layer is 1.4 × 10⁻⁶. 18 cm -3 ~2.8×10 19 cm -3 .

[0033] As an improvement to the above technical solution, the thickness of the first GaN layer is greater than the thickness of the second GaN layer, and the thickness of the second GaN layer is greater than the thickness of the fourth GaN layer.

[0034] As an improvement to the above technical solution, the first GaN layer is doped with Si, and the Si doping concentration is 1.8 × 10⁻⁶. 17 cm -3 ~7.6×10 17 cm -3 .

[0035] As an improvement to the above technical solution, the fourth GaN layer is doped with Mg, and the Mg doping concentration is 3.2 × 10⁻⁶. 18 cm -3 ~2.6×10 19 cm -3 .

[0036] Accordingly, the present invention also discloses a light-emitting diode, which includes the above-described light-emitting diode epitaxial wafer.

[0037] Implementing this invention has the following beneficial effects:

[0038] In one embodiment of the present invention, the epitaxial wafer of a light-emitting diode includes a first multiple quantum well layer, a first hole injection enhancement layer, a second multiple quantum well layer, a second hole injection enhancement layer, a third multiple quantum well layer, and a P-type semiconductor layer; the first multiple quantum well layer is In. x Ga 1-x The periodic structure formed by alternating N-layers and a first GaN layer has an emission wavelength of λ1; the first hole injection enhancement layer is In. α Ga 1-α N layers and In a Al b Ga 1-a-b The structure is a periodic structure formed by alternating N layers; the second quantum well layer is In. y Ga 1-y The periodic structure formed by alternating N-layers and second GaN layers has an emission wavelength of λ2; the second hole injection enhancement layer is In. β Ga 1-βThe structure is a periodic structure formed by alternating N-layers and a third GaN layer; the third multi-quantum-well layer is In. z Ga 1-z The periodic structure formed by alternating N-layers and a fourth GaN layer has an emission wavelength of λ3; where α < β < x < y < z, α ≥ a, and λ1 < λ2 ≤ λ3. Based on the above-mentioned LED epitaxial wafer, firstly, a first hole injection enhancement layer is introduced between the first and second multiple quantum well layers, and a second hole injection enhancement layer is introduced between the second and third multiple quantum well layers. These two layers facilitate the transport of hole carriers to the multiple quantum well layers closer to the N-type semiconductor layer, improving the hole injection efficiency. This results in relatively high recombination efficiency for the multiple quantum well layers corresponding to each wavelength band, improving luminous efficiency and optimizing the uniformity of light across different wavelength bands. Secondly, by using In in the region near the N-type semiconductor layer... α Ga 1-α N layers and In a Al b Ga 1-a-b The first hole injection enhancement layer, formed by alternating N layers, employs In in the region near the P-type semiconductor layer. β Ga 1-β The second hole injection enhancement layer, formed by alternating N-layers and a third GaN layer, and with α ≥ a controlled, allows for more efficient hole injection into the first multiple quantum well layer closer to the N-type semiconductor layer, thus optimizing the luminous efficiency of the first multiple quantum well layer. Thirdly, the In in the first hole injection enhancement layer... a Al b Ga 1-a-b The N-layer effectively prevents defects from the bottom layer from extending upwards, improving the crystal quality of subsequent layers. This allows the second and third quantum well layers to maintain high crystal quality even with a high In composition, weakening the polarization electric field and improving luminous efficiency. Fourthly, by controlling x < y < z, i.e., using a growth method with In composition increasing from low to high, the poor lattice quality of the first quantum well layer near the N-type semiconductor layer can be effectively avoided, resulting in low luminous efficiency and effectively reducing the inhomogeneity of light across different wavelengths. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of a light-emitting diode epitaxial wafer in one embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the structure of the first multi-quantum well layer in one embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the structure of the first hole injection enhancement layer in one embodiment of the present invention;

[0042] Figure 4This is a schematic diagram of the structure of the second multi-quantum well layer in one embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the structure of the second hole injection enhancement layer in one embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of the structure of the third multi-quantum well layer in one embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0046] See Figures 1-6 The present invention discloses a light-emitting diode epitaxial wafer, which includes a substrate 100, and an N-type semiconductor layer 200, a first multiple quantum well layer 300, a first hole injection enhancement layer 400, a second multiple quantum well layer 500, a second hole injection enhancement layer 600, a third multiple quantum well layer 700 and a P-type semiconductor layer 800 sequentially stacked on the substrate 100.

[0047] The first multi-quantum well layer 300 has a periodic structure, with each period consisting of sequentially stacked In... x Ga 1-x The first GaN layer 320 and the first multi-quantum well layer 300 emit light at a wavelength of λ1.

[0048] The first hole injection enhancement layer 400 has a periodic structure, and each period includes sequentially stacked In... α Ga 1-α N-layer 410 and In a Al b Ga 1-a-b Nth floor 420;

[0049] The second multiple quantum well layer 500 has a periodic structure, with each period consisting of sequentially stacked In... y Ga 1-y The N layer 510 and the second GaN layer 520; the emission wavelength of the second multiple quantum well layer 500 is λ2;

[0050] The second hole injection enhancement layer 600 has a periodic structure, and each period includes sequentially stacked In... β Ga 1-β N-layer 610 and third GaN layer 620;

[0051] The third multi-quantum well layer 700 is a periodic structure, with each period consisting of sequentially stacked In... z Ga 1-z The N-layer 710 and the fourth GaN layer 720; the third multiple quantum well layer 700 emits light at a wavelength of λ3;

[0052] Among them, α<β<x<y<z, α≥a, λ1<λ2≤λ3.

[0053] Based on the aforementioned LED epitaxial wafer, firstly, a first hole injection enhancement layer 400 (composed of In) is introduced between the first multiple quantum well layer 300 and the second multiple quantum well layer 500. α Ga 1-α N-layer 410 and In a Al b Ga 1-a-b N layers 420 are alternately stacked), and a second hole injection enhancement layer 600 (composed of In) is introduced between the second multi-quantum well layer 500 and the third multi-quantum well layer 700. β Ga 1-β (The N-layer 610 and the third GaN layer 620 are alternately stacked.) These two layers facilitate the transport of hole carriers to the multi-quantum well layer closer to the N-type semiconductor layer 200, improving the hole injection efficiency. This, in turn, ensures that the multi-quantum well layers corresponding to each wavelength band have relatively high recombination efficiencies, improving luminous efficiency and optimizing the uniformity of light across different wavelength bands. Both are achieved by using In in the region close to the N-type semiconductor layer 200. α Ga 1-α N-layer 410 and In a Al b Ga 1-a-b The first hole injection enhancement layer 400, formed by alternating N-layers 420, employs In in the region near the P-type semiconductor layer 800. β Ga 1-β The second hole injection enhancement layer 600, formed by alternating N-layer 610 and third GaN layer 620, and with α ≥ a controlled, forms a stepped band structure. This allows for more efficient hole injection into the first multiple quantum well layer 300, which is closer to the N-type semiconductor layer 200, thus optimizing the luminous efficiency of the first multiple quantum well layer 300. Thirdly, the In in the first hole injection enhancement layer 400... a Al b Ga 1-a-b The N-layer 420 effectively prevents defects from the bottom layer from extending upwards, improving the crystal quality of subsequent layers. This allows the second and third quantum well layers 500 and 700 to maintain high crystal quality even with a high In composition, weakening the polarization electric field and improving luminous efficiency. Fourthly, by controlling x < y < z, i.e., using a growth method with In composition increasing from low to high, the poor lattice quality of the first quantum well layer 300 near the N-type semiconductor layer 200 can be effectively avoided, resulting in low luminous efficiency and effectively reducing the non-uniformity of light across different wavelengths.

[0054] Specifically, in some embodiments, the number of periods of the first multiple quantum well layer 300 is ≥2, preferably 2~8, more preferably 2~5, and even more preferably 3~5. Specifically, in some embodiments, the emission wavelength (i.e., λ1) of the first multiple quantum well layer 300 is 400nm~430nm.

[0055] Specifically, in some implementation methods, In x Ga 1-x In layer N 310, the value of x ranges from 0.1 to 0.15, preferably from 0.11 to 0.15, more preferably from 0.11 to 0.14, and even more preferably from 0.12 to 0.14. x Ga 1-x The thickness of the N-layer 310 is 2nm~6nm, preferably 2nm~5nm, more preferably 2.1nm~4.6nm, and even more preferably 2.8nm~4.2nm.

[0056] Specifically, in some implementations, the thickness of the first GaN layer 320 is 8nm~20nm, preferably 8nm~18nm, more preferably 8.1nm~16.7nm, and even more preferably 9.5nm~13.5nm.

[0057] Specifically, in some embodiments, the number of cycles of the first hole injection enhancement layer 400 is 2 to 8, preferably 2 to 5, and more preferably 2 to 4.

[0058] Specifically, in some implementation methods, In α Ga 1-α In layer N 410, the value of α ranges from 0.005 to 0.1, preferably from 0.005 to 0.08, more preferably from 0.01 to 0.07, and even more preferably from 0.03 to 0.07. α Ga 1-α The thickness of the N layer 410 is 0.2nm~4nm, preferably 0.3nm~3nm, more preferably 0.3nm~2.8nm, and even more preferably 1.2nm~2.5nm.

[0059] Specifically, in some implementation methods, In a Al b Ga 1-a-b In layer N 420, the value of 'a' ranges from 0.005 to 0.07, preferably from 0.005 to 0.065, more preferably from 0.01 to 0.05, and even more preferably from 0.02 to 0.05. a Al b Ga 1-a-bIn layer N 420, the value of b ranges from 0.02 to 0.3, preferably from 0.02 to 0.2, more preferably from 0.05 to 0.15, and even more preferably from 0.08 to 0.12. a Al b Ga 1-a-b The thickness of the N-layer 420 is 0.2nm~4nm, preferably 0.5nm~3nm, more preferably 0.5nm~2.5nm, and even more preferably 1.2nm~2.5nm.

[0060] Specifically, in some embodiments, the number of periods of the second multiple quantum well layer 500 is ≥3, preferably 3~8, more preferably 3~6, ​​and even more preferably 4~6. Specifically, in some embodiments, the emission wavelength (i.e., λ2) of the second multiple quantum well layer 500 is 430nm~450nm.

[0061] Specifically, in some implementation methods, In y Ga 1-y In layer N 510, the value of y ranges from 0.15 to 0.18, preferably from 0.15 to 0.17, and more preferably from 0.15 to 0.16. y Ga 1-y The thickness of the N-layer 510 is 2nm~6nm, preferably 2nm~5nm, and more preferably 2.1nm~4.6nm.

[0062] Specifically, in some embodiments, the thickness of the second GaN layer 520 is 7nm to 20nm; preferably 7nm to 18nm, more preferably 7.3nm to 15.8nm, and even more preferably 8nm to 11nm.

[0063] Specifically, in some embodiments, the number of cycles of the second hole injection enhancement layer 600 is 2 to 10, preferably 2 to 8, and more preferably 3 to 7.

[0064] Specifically, in some implementation methods, In β Ga 1-β In layer N 610, the value of β ranges from 0.008 to 0.1, preferably from 0.01 to 0.1, more preferably from 0.03 to 0.1, and even more preferably from 0.05 to 0.08. β Ga 1-β The thickness of the N-layer 610 is 0.5nm to 4nm, preferably 0.5nm to 3nm, more preferably 0.5nm to 2.5nm, and even more preferably 0.5nm to 1.5nm.

[0065] Specifically, in some embodiments, the thickness of the third GaN layer 620 is 0.5nm to 4nm, preferably 0.5nm to 3nm, more preferably 0.5nm to 2.5nm, and even more preferably 1nm to 2.5nm.

[0066] Specifically, in some embodiments, the number of periods of the third multiple quantum well layer 700 is ≥2, preferably 2~8, more preferably 2~5, and even more preferably 3~5. Specifically, in some embodiments, the emission wavelength (i.e., λ3) of the third multiple quantum well layer 700 is 445nm~455nm.

[0067] Specifically, in some implementation methods, In z Ga 1-z In layer N 710, the value of z ranges from 0.17 to 0.2, preferably from 0.17 to 0.19, and more preferably from 0.18 to 0.19. z Ga 1-z The thickness of the N-layer 710 is 2nm~6nm, preferably 2nm~5nm, and more preferably 2.5nm~4nm.

[0068] Specifically, in some embodiments, the thickness of the fourth GaN layer 720 is 5nm~20nm, preferably 6nm~18nm, more preferably 6.5nm~15nm, and even more preferably 7nm~10nm.

[0069] Specifically, in some embodiments, the substrate 100 is a sapphire substrate, a silicon substrate, or a silicon carbide substrate, but is not limited thereto. Preferably, it is a sapphire substrate.

[0070] Specifically, in some embodiments, the N-type semiconductor layer 200 is an N-type GaN layer with a doping concentration of 5 × 10⁻⁶. 18 cm -3 ~5×10 19 cm -3 The thickness is 1μm~5μm.

[0071] Specifically, in some implementations, the P-type semiconductor layer 800 is a P-type GaN layer with a thickness of 50 nm to 200 nm and a Mg doping concentration of 1 × 10⁻⁶. 19 cm -3 ~5×10 20 cm -3 .

[0072] Preferably, in some embodiments, the light-emitting diode epitaxial wafer further includes a buffer layer 110, an undoped GaN layer 120, and an electron blocking layer 900. The buffer layer 110 and the undoped GaN layer 120 are sequentially disposed between the substrate 100 and the N-type semiconductor layer 200. Specifically, the buffer layer 110 is an AlN layer or an AlGaN layer, but is not limited thereto. The thickness of the buffer layer 110 is 20 nm to 80 nm. The thickness of the undoped GaN layer 120 is 1 μm to 3 μm. The electron blocking layer 900 is disposed between the third multiple quantum well layer 700 and the P-type semiconductor layer 800, and is an AlInGaN layer or an AlGaN layer, but is not limited thereto. Preferably, it is an AlInGaN layer, with an Al content of 0.01 to 0.1%, an In content of 0.01 to 0.2%, and a thickness of 10 nm to 50 nm.

[0073] Preferably, in some embodiments, In α Ga 1-α Mg and In are doped in the N-layer 410. β Ga 1-β Mg is doped in the N-layer 610; Mg doping provides some holes, thereby improving radiative recombination efficiency and luminescence efficiency. Specifically, In β Ga 1-β The Mg doping concentration in the N-layer 610 is less than that in In. α Ga 1-α The Mg doping concentration of the N-layer 410. More specifically, In α Ga 1-α The Mg doping concentration of the N-layer 410 is 3.2 × 10⁻⁶. 18 cm -3 ~5.6×10 19 cm -3 In β Ga 1-β The Mg doping concentration of the N-layer 610 is 1.4 × 10⁻⁶. 18 cm -3 ~2.8×10 19 cm -3 .

[0074] Preferably, in some embodiments, the thickness of the first GaN layer 320 is greater than the thickness of the second GaN layer 520, and the thickness of the second GaN layer 520 is greater than the thickness of the fourth GaN layer 720. This structure can further reduce the obstruction of holes, making it easier for holes to be injected into the multi-quantum well layer close to the N-type semiconductor layer 200, and optimizing the uniformity of light in each wavelength band.

[0075] Preferably, in some embodiments, the first GaN layer 320 is doped with Si, and the Si doping concentration is 1.8 × 10⁻⁶. 17 cm-3 ~7.6×10 17 cm -3 Since the first multiple quantum well layer 300 is closer to the N-type semiconductor layer 200, it has more defects and a stronger polarization effect. Therefore, it is doped with Si to weaken the polarization effect and improve the luminous efficiency. After being blocked by the first hole injection enhancement layer 400, the extended defects are reduced. Therefore, the barrier in the second multiple quantum well layer 500 and the third multiple quantum well layer 700 can adopt an undoped structure or other structures.

[0076] Preferably, in some embodiments, the fourth GaN layer 720 is doped with Mg at a doping concentration of 3.2 × 10⁻⁶. 18 cm -3 ~2.6×10 19 cm -3 Based on this structure, holes can be accelerated, allowing more of them to be transported to the multi-quantum-well layer close to the N-type semiconductor layer 200, thus optimizing uniformity.

[0077] Accordingly, the present invention also discloses a light-emitting diode, which includes the above-described light-emitting diode epitaxial wafer.

[0078] The present invention will be further described below with reference to specific embodiments:

[0079] Example 1

[0080] This embodiment provides a light-emitting diode epitaxial wafer, which includes a substrate, and a buffer layer, an undoped GaN layer, an N-type semiconductor layer, a first multiple quantum well layer, a first hole injection enhancement layer, a second multiple quantum well layer, a third multiple quantum well layer, an electron blocking layer, and a P-type semiconductor layer, which are sequentially stacked on the substrate.

[0081] The substrate is sapphire, the buffer layer is an AlN layer with a thickness of 50 nm, and the undoped GaN layer has a thickness of 3 μm. The N-type semiconductor layer is an N-type GaN layer with a Si doping concentration of 9.4 × 10⁻⁶. 18 cm -3 The thickness is 2.5μm.

[0082] The first multi-quantum-well layer has a periodic structure with four periods, and each period includes sequentially stacked In... x Ga 1-x N layers (x=0.13) and the first GaN layer; In x Ga 1-x The thickness of the N layer is 3.2 nm, and the thickness of the first GaN layer is 10 nm.

[0083] The first hole injection enhancement layer has a periodic structure with three cycles. Each cycle includes sequentially stacked In... α Ga1-α N layers (α=0.05) and In a Al b Ga 1-a-b N layers (a=0.03, b=0.1); In α Ga 1-α The thickness of the N layer is 1.5 nm, In a Al b Ga 1-a-b The thickness of the N layer is 2nm.

[0084] The second multiple quantum well layer has a periodic structure with 6 periods, each period consisting of sequentially stacked In... y Ga 1-y N-layer (y=0.16) and the second GaN layer; In y Ga 1-y The thickness of the N layer is 3nm, and the thickness of the second GaN layer is 10nm.

[0085] The second hole injection enhancement layer has a periodic structure with 5 periods, each period consisting of sequentially stacked In... β Ga 1-β The N-layer (β=0.07) and the third GaN layer; In β Ga 1-β The thickness of the N layer is 1.2 nm, and the thickness of the third GaN layer is 2 nm.

[0086] The third multi-quantum-well layer has a periodic structure with four periods, each period consisting of sequentially stacked In... z Ga 1-z N-layer (z=0.19) and the fourth GaN layer; In z Ga 1-z The thickness of the N layer is 3.5 nm, and the thickness of the fourth GaN layer is 10 nm.

[0087] The electron blocking layer is an AlInGaN layer with an Al content of 0.05% and an In content of 0.06%, and a thickness of 40 nm. The p-type semiconductor layer is a p-type GaN layer with a thickness of 180 nm and a Mg doping concentration of 5 × 10⁻⁶. 20 cm -3 .

[0088] Example 2

[0089] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 1 in that:

[0090] In α Ga 1-α The N-layer is doped with Mg at a concentration of 2.5 × 10⁻⁶. 19 cm -3In β Ga 1-β The N-layer is doped with Mg; the doping concentration is 3.5 × 10⁻⁶. 18 cm -3 .

[0091] Everything else is the same as in Example 1.

[0092] Example 3

[0093] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 2 in that:

[0094] The thickness of the first GaN layer is 12.5 nm, the thickness of the second GaN layer is 10.5 nm, and the thickness of the fourth GaN layer is 8.5 nm.

[0095] Everything else is the same as in Example 2.

[0096] Example 4

[0097] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 3 in that:

[0098] The first GaN layer is doped with Si, and its doping concentration is 5.4 × 10⁻⁶. 17 cm -3 .

[0099] Everything else is the same as in Example 3.

[0100] Example 5

[0101] This embodiment provides a light-emitting diode epitaxial wafer, which differs from Embodiment 4 in that:

[0102] The fourth GaN layer is doped with Mg at a concentration of 5.2 × 10⁻⁶. 18 cm -3 .

[0103] Everything else is the same as in Example 4.

[0104] Comparative Example 1

[0105] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that:

[0106] Excluding the first hole injection enhancement layer and the second hole injection enhancement layer.

[0107] Everything else is the same as in Example 1.

[0108] Comparative Example 2

[0109] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that:

[0110] A third multiple quantum well layer, a second hole injection enhancement layer, a second multiple quantum well layer, a first hole injection enhancement layer, and a first multiple quantum well layer are sequentially stacked on an N-type semiconductor layer.

[0111] Everything else is the same as in Example 1.

[0112] Comparative Example 3

[0113] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that:

[0114] A first multiple quantum well layer, a second hole injection enhancement layer, a second multiple quantum well layer, a first hole injection enhancement layer, and a third multiple quantum well layer are sequentially stacked on an N-type semiconductor layer.

[0115] Everything else is the same as in Example 1.

[0116] Comparative Example 4

[0117] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that:

[0118] Excluding the first hole injection enhancement layer;

[0119] Everything else is the same as in Example 1.

[0120] Comparative Example 5

[0121] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that:

[0122] It does not contain a second hole injection enhancement layer.

[0123] Everything else is the same as in Example 1.

[0124] The LED epitaxial wafers obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were fabricated into chips of 10mil × 24mil. Their brightness at 200mA was tested, and the brightness improvement rate was calculated based on the data of Comparative Example 1.

[0125] Specifically, the brightness improvement rate = (brightness of each embodiment / comparative example - brightness of Comparative Example 1) / brightness of Comparative Example 1. The specific results are shown in the table below:

[0126]

[0127] The above description is a preferred embodiment of the invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the invention, and these improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A light emitting diode epitaxial wafer, characterized by, The light emitting diode epitaxial wafer comprises a substrate, an N-type semiconductor layer, a first multi-quantum well layer, a first hole injection enhancement layer, a second multi-quantum well layer, a second hole injection enhancement layer, a third multi-quantum well layer and a P-type semiconductor layer which are sequentially stacked on the substrate. The first multi-quantum well layer is a periodic structure, each period comprising, in sequence, an In x Ga 1-x N layer and a first GaN layer; the first multi-quantum well layer has a light emission wavelength of λ1; the first GaN layer is doped with Si; The first hole injection enhancement layer is a periodic structure, each period comprising In α Ga 1-α N layers and In a Al b Ga 1-a-b N layers stacked in sequence. The second multiple quantum well layer is a periodic structure, each period comprising a first InGaN layer, a second GaN layer, a third InGaN layer, and a fourth GaN layer, which are sequentially stacked y Ga 1-y N layers; the light-emitting wavelength of the second multiple quantum well layer is λ2; the second GaN layer is a non-doped GaN layer; The second hole injection enhancement layer is a periodic structure, each period comprising, in sequence, an In β Ga 1-β N layer and a third GaN layer. The third multiple quantum well layer is a periodic structure, each period comprising, in sequence, an In z Ga 1-z N layer and a fourth GaN layer; the light emission wavelength of the third multiple quantum well layer is λ3; the fourth GaN layer is doped with Mg; The value range of a is 0.02-0.5, the value range of b is 0.08-0.12, α < β < x < y < z, α ≥ a, λ1 < λ2 ≤ λ3.

2. The light emitting diode epitaxial wafer of claim 1, wherein, The period number of the first multi-quantum well layer is ≥2, the period number of the second multi-quantum well layer is ≥3, and the period number of the third multi-quantum well layer is ≥2.

3. The light emitting diode epitaxial wafer of claim 1, wherein, The period number of the first multi-quantum well layer is 2-5; and / or The In x Ga 1-x x in the InGaN layer ranges from 0.11 to 0.15, and the thickness thereof is 2 nm to 5 nm; and / or The thickness of the first GaN layer is 8-18 nm; and / or The period number of the second multi-quantum well layer is 3-6; and / or The In y Ga 1-y y in the GaN layer ranges from 0.15 to 0.17, and the thickness thereof is 2 nm to 5 nm; and / or The thickness of the second GaN layer is 7-18 nm; and / or The period number of the third multi-quantum well layer is 2-5; and / or The In z Ga 1-z z in the GaN layer ranges from 0.17 to 0.19, and the thickness of the GaN layer is 2 nm to 5 nm; and / or The thickness of the fourth GaN layer is 6-18 nm.

4. The light emitting diode epitaxial wafer of claim 1, wherein, The period number of the first hole injection enhancement layer is 2-5; and / or said In α Ga 1-α α in the InGaN layer ranges from 0.005 to 0.08, and the thickness thereof ranges from 0.3 nm to 3 nm; and / or the In a Al b Ga 1-a-b a thickness of the N layer is 0.5 nm to 3 nm; and / or The period number of the second hole injection enhancement layer is 2-8; and / or said In β Ga 1-β β in the GaN layer ranges from 0.01 to 0.1 and has a thickness of 0.5 nm to 3 nm; and / or The thickness of the third GaN layer is 0.5-3 nm.

5. The light emitting diode epitaxial wafer of claim 1, wherein, In α Ga 1-α N layer doped with Mg, In β Ga 1-β N layer doped with Mg; said In β Ga 1-β N layer is less than the Mg doping concentration of said In α Ga 1-α N layer.

6. The light emitting diode epitaxial wafer of claim 5, wherein, The In α Ga 1-α N layer has a Mg doping concentration of 3.2 x 10 18 cm -3 ~5.6 x 10 19 cm -3 ; The In β Ga 1-β N layer has a Mg doping concentration of 1.4 x 10 18 cm -3 ~2.8 x 10 19 cm -3 .

7. The light emitting diode epitaxial wafer of claim 1, wherein, The thickness of the first GaN layer is greater than that of the second GaN layer, and the thickness of the second GaN layer is greater than that of the fourth GaN layer.

8. The light emitting diode epitaxial wafer of claim 1, wherein, The Si doping concentration of the first GaN layer is 1.8 x 1018cm-3 17 cm -3 ~7.6 x 1018cm-3 17 cm -3 .

9. The light emitting diode epitaxial wafer of claim 1, wherein, The Mg doping concentration in the fourth GaN layer is 3.2 x 1019cm-3 18 cm -3 -2.6 x 1019cm-3 19 cm -3 .

10. A light emitting diode, comprising: The light emitting diode epitaxial wafer comprises a substrate, an N-type semiconductor layer, a first multi-quantum well layer, a first hole injection enhancement layer, a second multi-quantum well layer, a second hole injection enhancement layer, a third multi-quantum well layer and a P-type semiconductor layer which are sequentially stacked on the substrate.

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