Light emitting diode epitaxial wafer and light emitting diode

Abstract

The invention discloses a light-emitting diode epitaxial wafer and a 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 of the first multi-quantum well layer is lambda 1; the first hole injection enhancement layer comprises an In < alpha > Ga < 1-alpha > N layer and an In Al 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 of the second multi-quantum well layer is lambda 2; the second hole injection enhancement layer comprises an In [beta] Ga [1-beta] N layer and a third GaN layer; the third multi-quantum well layer comprises an InzGa1-zN layer and a fourth GaN layer which are stacked in sequence, and the light emitting wavelength of the third multi-quantum well layer is lambda 3; alpha < beta < x < y < z, alpha > = a, and lambda1 < lambda2 < = lambda3. By implementing the invention, the uniformity and luminous efficiency of light of each wave band can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor optoelectronic devices, and in particular to a light emitting diode epitaxial wafer and a light emitting diode. Background Art

[0002] Multi-band LED chips are a key tool in the development of full-spectrum lighting. To achieve multi-band emission, multi-quantum well layers with varying indium compositions must be designed within the active light-emitting region. To ensure stable emission, these layers require a sufficient number of periods, resulting in a higher number of periods in the active light-emitting region compared to conventional single-band LED chips. However, using a higher number of periods in these layers makes it difficult for holes to effectively enter the underlying light-emitting region near the N-type layer, resulting in unstable emission from the multi-quantum well layer located in this region.

[0003] On the other hand, in order to improve the crystal quality of the quantum well layer (made of InGaN), a quantum well layer with a higher In component is often used in the area close to the N-type layer, and a quantum well layer with a lower In component is used in the area close to the P-type layer, so as to gradually increase the growth temperature and improve the crystal quality. However, the inventors further discovered that the poor crystal quality of the InGaN layer with a high In component often leads to amplification of defects propagating from the substrate, resulting in an excessively strong polarization effect at the bottom layer and a significant reduction in the overlap of the hole and electron wave functions, resulting in a lower luminous efficiency of the multi-quantum well layer corresponding to the light in this band. Moreover, the lattice mismatch of the multi-quantum well layer close to the P-type layer is small, and the recombination efficiency of electrons and holes in this area is high, which also leads to a higher luminous efficiency of the multi-quantum well layer in this area. The non-uniformity of the light in each band of the entire LED chip is high, which brings greater difficulty to subsequent dimming. Summary of the Invention

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

[0005] Another technical problem to be solved by the present invention is to provide a light emitting diode.

[0006] In order to solve the above problems, the present invention discloses a light-emitting diode epitaxial wafer, which includes 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 stacked in sequence on the substrate; The first multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In x Ga 1-x N layer and a first GaN layer; the emission wavelength of the first multi-quantum well layer is λ1; The first hole injection enhancement layer is a periodic structure, and each period includes sequentially stacked In α Ga 1-α N layer and In a Al b Ga 1-a-b N-layer; The second multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In y Ga 1-y N layer and a second GaN layer; the emission wavelength of the second multi-quantum well layer is λ2; The second hole injection enhancement layer is a periodic structure, each period includes sequentially stacked In β Ga 1-β N layer and a third GaN layer; The third multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In z Ga 1-z N layer and a fourth GaN layer; the emission wavelength of the third multi-quantum well layer is λ3; Among them, α<β<x<y<z, α≥a, λ1<λ2≤λ3.

[0007] As an improvement of the above technical solution, 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.

[0008] As an improvement to the above technical solution, the number of periods of the first multi-quantum well layer is 2 to 5; and / or In x Ga 1-x The value of x in the N layer ranges from 0.11 to 0.15, and its thickness ranges from 2 nm to 5 nm; and / or The thickness of the first GaN layer is 8 nm to 18 nm; and / or The number of periods of the second multi-quantum well layer is 3 to 6; and / or In y Ga 1-y The value of y in the N layer ranges from 0.15 to 0.17, and its thickness ranges from 2 nm to 5 nm; and / or The thickness of the second GaN layer is 7 nm to 18 nm; and / or The number of periods of the third multi-quantum well layer is 2 to 5; and / or In z Ga 1-z The value of z in the N layer ranges from 0.17 to 0.19, and its thickness ranges from 2 nm to 5 nm; and / or The thickness of the fourth GaN layer is 6 nm to 18 nm.

[0009] As an improvement to the above technical solution, the number of periods of the first hole injection enhancement layer is 2 to 5; and / or In α Ga 1-α The value of α in the N layer ranges from 0.005 to 0.08, and its thickness ranges from 0.3 nm to 3 nm; and / or In a Al b Ga 1-a-b In the N layer, 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 ranges from 0.5 nm to 3 nm; and / or The number of periods of the second hole injection enhancement layer is 2 to 8; and / or In β Ga 1-β The value of β in the N layer ranges from 0.01 to 0.1, and its thickness ranges from 0.5 nm to 3 nm; and / or The thickness of the third GaN layer is 0.5 nm to 3 nm.

[0010] As an improvement of the above technical solution, the In α Ga 1-α The N layer is doped with Mg, the In β Ga 1-β The N layer is doped with Mg; In β Ga 1-β The Mg doping concentration of the N layer is lower than that of the In α Ga 1-α Mg doping concentration of the N layer.

[0011] As an improvement of the above technical solution, the In α Ga 1-α The Mg doping concentration of the N layer is 3.2×10 18 cm -3 ~5.6×10 19 cm -3 ; In β Ga 1-β The Mg doping concentration of the N layer is 1.4×10 18 cm -3 ~2.8×10 19 cm -3 .

[0012] As an improvement of 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.

[0013] 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 17 cm -3 ~7.6×10 17 cm -3 .

[0014] As an improvement to the above technical solution, the fourth GaN layer is doped with Mg, and its Mg doping concentration is 3.2×10 18 cm -3 ~2.6×10 19 cm -3 .

[0015] Correspondingly, the present invention also discloses a light emitting diode, which includes the light emitting diode epitaxial wafer mentioned above.

[0016] The implementation of the present invention has the following beneficial effects: The light emitting diode epitaxial wafer in one embodiment of the present invention 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, a third multi-quantum well layer and a P-type semiconductor layer; the first multi-quantum well layer is In x Ga 1-x The periodic structure formed by alternating N layers and the first GaN layer has a light emission wavelength of λ1; the first hole injection enhancement layer is In α Ga 1-α N layer and In a Al b Ga 1-a-b The periodic structure is formed by alternating N layers; the second multi-quantum well layer is In y Ga 1-y The periodic structure formed by alternating N layer and the second GaN layer has a light emission wavelength of λ2; the second hole injection enhancement layer is In β Ga 1-β The N layer and the third GaN layer are alternately stacked to form a periodic structure; the third multi-quantum well layer is In z Ga 1-zThe periodic structure formed by the alternating stacking of the N layer and the fourth GaN layer has a light emission wavelength of λ3; wherein, α<β<x<y<z, α≥a, λ1<λ2≤λ3. Based on the above-mentioned light-emitting diode epitaxial wafer, firstly, a first hole injection enhancement layer is introduced between the first multi-quantum well layer and the second multi-quantum well layer, and a second hole injection enhancement layer is introduced between the second multi-quantum well layer and the third multi-quantum well layer. These two layers help hole carriers to be transferred to the multi-quantum well layer closer to the N-type semiconductor layer, thereby improving the hole injection efficiency, thereby making the multi-quantum well layer corresponding to each band of light have a relatively high recombination efficiency, improving the luminous efficiency, and optimizing the uniformity of each band of light. Secondly, by using In in the area close to the N-type semiconductor layer α Ga 1-α N layer and In a Al b Ga 1-a-b The first hole injection enhancement layer formed by alternately stacking N layers is formed by using In in the area close to the P-type semiconductor layer. β Ga 1-β The second hole injection enhancement layer is formed by alternating N layers and the third GaN layer, and controlling α≥a can make holes more effectively injected into the first multi-quantum well layer closer to the N-type semiconductor layer, thereby optimizing the luminous efficiency of the first multi-quantum well layer. a Al b Ga 1-a-b The N layer effectively blocks defects from the bottom layer from extending upward, improving the crystal quality of subsequent layers. This ensures that the second and third multi-quantum well layers maintain high crystal quality even when using high In content, weakening the polarization electric field and improving luminous efficiency. Furthermore, by controlling x < y < z, i.e., adopting a low-to-high In content growth method, the poor lattice quality and low luminous efficiency of the first multi-quantum well layer near the N-type semiconductor layer can be effectively avoided, effectively reducing the unevenness of light across different bands. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a schematic structural diagram of a light emitting diode epitaxial wafer according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of a first multi-quantum well layer in one embodiment of the present invention; Figure 3 is a schematic structural diagram of a first hole injection enhancement layer in one embodiment of the present invention; Figure 4 is a schematic structural diagram of a second multi-quantum well layer in one embodiment of the present invention; Figure 5 is a schematic structural diagram of a second hole injection enhancement layer in one embodiment of the present invention; Figure 6Schematic diagram of the structure of the third multi-quantum well layer in one embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0019] See also Figures 1 to 6 The present invention discloses a light-emitting diode epitaxial wafer, which includes a substrate 100, an N-type semiconductor layer 200, a first multi-quantum well layer 300, a first hole injection enhancement layer 400, a second multi-quantum well layer 500, a second hole injection enhancement layer 600, a third multi-quantum well layer 700 and a P-type semiconductor layer 800 stacked in sequence on the substrate 100.

[0020] The first multi-quantum well layer 300 is a periodic structure, and each period includes sequentially stacked In x Ga 1-x N layer 310 and first GaN layer 320; the emission wavelength of the first multi-quantum well layer 300 is λ1; The first hole injection enhancement layer 400 is 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 N layer 420; The second multi-quantum well layer 500 is a periodic structure, and each period includes sequentially stacked In y Ga 1-y The N layer 510 and the second GaN layer 520; the light emission wavelength of the second multi-quantum well layer 500 is λ2; The second hole injection enhancement layer 600 is a periodic structure, and each period includes sequentially stacked In β Ga 1-β N layer 610 and third GaN layer 620; The third multi-quantum well layer 700 is a periodic structure, and each period includes sequentially stacked In z Ga 1-z N layer 710 and fourth GaN layer 720; the emission wavelength of the third multi-quantum well layer 700 is λ3; Among them, α<β<x<y<z, α≥a, λ1<λ2≤λ3.

[0021] Based on the above-mentioned light-emitting diode epitaxial wafer, firstly, a first hole injection enhancement layer 400 (composed of In α Ga 1-α N layer 410 and In a Alb Ga 1-a-b N layers 420 are alternately stacked, and a second hole injection enhancement layer 600 (composed of In β Ga 1-β The N layer 610 and the third GaN layer 620 are alternately stacked. These two layers help hole carriers to be transferred to the multi-quantum well layer closer to the N-type semiconductor layer 200, thereby improving the hole injection efficiency. As a result, the multi-quantum well layer corresponding to each wavelength has a relatively high recombination efficiency, thereby improving the luminous efficiency and optimizing the uniformity of each wavelength. α Ga 1-α N layer 410 and In a Al b Ga 1-a-b The first hole injection enhancement layer 400 is formed by alternately stacking the N layer 420, and the In β Ga 1-β The second hole injection enhancement layer 600 is formed by alternating the N layer 610 and the third GaN layer 620, and α≥a is controlled to form a stepped band structure, which can more effectively inject holes into the first multi-quantum well layer 300 closer to the N-type semiconductor layer 200, thereby optimizing the luminous efficiency of the first multi-quantum well layer 300. a Al b Ga 1-a-b The N-type layer 420 effectively blocks defects from the underlying layer from extending upward, improving the crystal quality of subsequent layers. This ensures that the second and third multi-quantum well layers 500 and 700 maintain high crystal quality even when using a high In composition, weakening the polarization electric field and improving luminous efficiency. Furthermore, by controlling x < y < z (i.e., adopting a low-to-high In composition growth strategy), the poor lattice quality and low luminous efficiency of the first multi-quantum well layer 300 near the N-type semiconductor layer 200 are effectively avoided, effectively reducing the unevenness of light across different wavelengths.

[0022] Specifically, in some embodiments, the period number of the first multi-quantum well layer 300 is ≥ 2, preferably 2 to 8, more preferably 2 to 5, and even more preferably 3 to 5. Specifically, in some embodiments, the emission wavelength (i.e., λ1) of the first multi-quantum well layer 300 is 400 nm to 430 nm.

[0023] Specifically, in some embodiments, x Ga 1-xThe value range of x in the N layer 310 is 0.1 to 0.15, preferably 0.11 to 0.15, more preferably 0.11 to 0.14, and further preferably 0.12 to 0.14. x Ga 1-x The thickness of the N layer 310 is 2 nm to 6 nm, preferably 2 nm to 5 nm, more preferably 2.1 nm to 4.6 nm, and further preferably 2.8 nm to 4.2 nm.

[0024] Specifically, in some embodiments, the thickness of the first GaN layer 320 is 8 nm to 20 nm, preferably 8 nm to 18 nm, more preferably 8.1 nm to 16.7 nm, and even more preferably 9.5 nm to 13.5 nm.

[0025] Specifically, in some embodiments, the number of periods of the first hole injection enhancement layer 400 is 2-8, preferably 2-5, and more preferably 2-4.

[0026] Specifically, in some embodiments, α Ga 1-α The value range of α in the N layer 410 is 0.005-0.1, preferably 0.005-0.08, more preferably 0.01-0.07, and further preferably 0.03-0.07. α Ga 1-α The thickness of the N layer 410 is 0.2 nm to 4 nm, preferably 0.3 nm to 3 nm, more preferably 0.3 nm to 2.8 nm, and further preferably 1.2 nm to 2.5 nm.

[0027] Specifically, in some embodiments, a Al b Ga 1-a-b The value range of a in the N layer 420 is 0.005-0.07, preferably 0.005-0.065, more preferably 0.01-0.05, and further preferably 0.02-0.05. a Al b Ga 1-a-b The value range of b in the N layer 420 is 0.02-0.3, preferably 0.02-0.2, more preferably 0.05-0.15, and further preferably 0.08-0.12. a Al b Ga 1-a-b The thickness of the N layer 420 is 0.2 nm to 4 nm, preferably 0.5 nm to 3 nm, more preferably 0.5 nm to 2.5 nm, and further preferably 1.2 nm to 2.5 nm.

[0028] Specifically, in some embodiments, the period number of the second multi-quantum well layer 500 is ≥ 3, preferably 3 to 8, more preferably 3 to 6, and even more preferably 4 to 6. Specifically, in some embodiments, the emission wavelength (i.e., λ2) of the second multi-quantum well layer 500 is 430 nm to 450 nm.

[0029] Specifically, in some embodiments, y Ga 1-y The value range of y in the N layer 510 is 0.15-0.18, preferably 0.15-0.17, and more preferably 0.15-0.16. y Ga 1-y The thickness of the N layer 510 is 2 nm to 6 nm, preferably 2 nm to 5 nm, and more preferably 2.1 nm to 4.6 nm.

[0030] Specifically, in some embodiments, the thickness of the second GaN layer 520 is 7 nm to 20 nm, preferably 7 nm to 18 nm, more preferably 7.3 nm to 15.8 nm, and even more preferably 8 nm to 11 nm.

[0031] Specifically, in some embodiments, the number of periods of the second hole injection enhancement layer 600 is 2-10, preferably 2-8, and more preferably 3-7.

[0032] Specifically, in some embodiments, β Ga 1-β The value range of β in the N layer 610 is 0.008~0.1, preferably 0.01~0.1, more preferably 0.03~0.1, and further preferably 0.05~0.08. β Ga 1-β The thickness of the N layer 610 is 0.5 nm to 4 nm, preferably 0.5 nm to 3 nm, more preferably 0.5 nm to 2.5 nm, and further preferably 0.5 nm to 1.5 nm.

[0033] Specifically, in some embodiments, the thickness of the third GaN layer 620 is 0.5 nm to 4 nm, preferably 0.5 nm to 3 nm, more preferably 0.5 nm to 2.5 nm, and even more preferably 1 nm to 2.5 nm.

[0034] Specifically, in some embodiments, the period number of the third multi-quantum well layer 700 is ≥ 2, preferably 2 to 8, more preferably 2 to 5, and even more preferably 3 to 5. Specifically, in some embodiments, the emission wavelength (i.e., λ3) of the third multi-quantum well layer 700 is 445 nm to 455 nm.

[0035] Specifically, in some embodiments, z Ga 1-z The value range of z in the N layer 710 is 0.17~0.2, preferably 0.17~0.19, and more preferably 0.18~0.19. z Ga 1-z The thickness of the N layer 710 is 2 nm to 6 nm, preferably 2 nm to 5 nm, and more preferably 2.5 nm to 4 nm.

[0036] Specifically, in some embodiments, the thickness of the fourth GaN layer 720 is 5 nm to 20 nm, preferably 6 nm to 18 nm, more preferably 6.5 nm to 15 nm, and even more preferably 7 nm to 10 nm.

[0037] Specifically, in some embodiments, the substrate 100 is a sapphire substrate, a silicon substrate, or a silicon carbide substrate, but is not limited thereto, and is preferably a sapphire substrate.

[0038] Specifically, in some embodiments, the N-type semiconductor layer 200 is an N-type GaN layer with a doping concentration of 5×10 18 cm -3 ~5×10 19 cm -3 , thickness is 1μm~5μm.

[0039] Specifically, in some embodiments, 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 19 cm -3 ~5×10 20 cm -3 .

[0040] 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 buffer layer 110 has a thickness of 20 nm to 80 nm. The undoped GaN layer 120 has a thickness of 1 μm to 3 μm. The electron blocking layer 900 is disposed between the third multi-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, wherein the Al component ratio is 0.01 to 0.1, the In component ratio is 0.01 to 0.2, and the thickness is 10 nm to 50 nm.

[0041] Preferably, in some embodiments, In αGa 1-α The N layer 410 is doped with Mg, In β Ga 1-β The N layer 610 is doped with Mg; Mg doping can provide some holes, thereby improving the radiation recombination efficiency and the luminous efficiency. β Ga 1-β The Mg doping concentration of the N layer 610 is lower than that of the In α Ga 1-α The Mg doping concentration of the N layer 410 is more specifically α Ga 1-α The Mg doping concentration of the N layer 410 is 3.2×10 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 18 cm -3 ~2.8×10 19 cm -3 .

[0042] 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 blocking of holes, making it easier for holes to be injected into the multi-quantum well layer close to the N-type semiconductor layer 200, thereby optimizing the uniformity of light in each band.

[0043] Preferably, in some embodiments, the first GaN layer 320 is doped with Si, and the Si doping concentration is 1.8×10 17 cm -3 ~7.6×10 17 cm -3 Because the first multi-quantum well layer 300 is closer to the N-type semiconductor layer 200 and has more defects and a stronger polarization effect, it is doped with Si to weaken the polarization effect and improve luminous efficiency. However, after being blocked by the first hole injection enhancement layer 400, the extended defects are reduced, so the potential barriers in the second multi-quantum well layer 500 and the third multi-quantum well layer 700 can adopt a non-doped structure or other structures.

[0044] Preferably, in some embodiments, the fourth GaN layer 720 is doped with Mg, and the doping concentration thereof is 3.2×10 18 cm -3 ~2.6×10 19 cm -3Based on this structure, holes can be accelerated so that more holes are transferred to the multi-quantum well layer close to the N-type semiconductor layer 200, thereby optimizing uniformity.

[0045] Correspondingly, the present invention also discloses a light emitting diode, which includes the light emitting diode epitaxial wafer mentioned above.

[0046] The present invention will be further described below with specific embodiments: Example 1 This embodiment provides a light-emitting diode epitaxial wafer, which includes a substrate, a buffer layer, an undoped GaN layer, 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, an electron blocking layer, and a P-type semiconductor layer stacked sequentially on the substrate; The substrate is a sapphire substrate, the buffer layer is an AlN layer with a thickness of 50 nm, and the thickness of the undoped GaN layer is 3 μm. The N-type semiconductor layer is an N-type GaN layer with a Si doping concentration of 9.4×10 18 cm -3 , with a thickness of 2.5μm.

[0047] The first multi-quantum well layer is a periodic structure with 4 periods, and each period includes sequentially stacked In x Ga 1-x N layer (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.

[0048] The first hole injection enhancement layer is a periodic structure with a period number of 3. Each period includes In α Ga 1-α N layer (α=0.05) and In a Al b Ga 1-a-b N layers (a=0.03, b=0.1); α Ga 1-α The thickness of the N layer is 1.5 nm, and the In a Al b Ga 1-a-b The thickness of the N layer is 2 nm.

[0049] The second multi-quantum well layer is a periodic structure with 6 periods. Each period includes In y Ga 1-y N layer (y = 0.16) and the second GaN layer; In y Ga 1-yThe thickness of the N layer is 3 nm, and the thickness of the second GaN layer is 10 nm.

[0050] The second hole injection enhancement layer is a periodic structure with 5 periods, each period including In β Ga 1-β 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.

[0051] The third multi-quantum well layer is a periodic structure with 4 periods. Each period includes 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.

[0052] The electron blocking layer is an AlInGaN layer with an Al component ratio of 0.05, an In component ratio of 0.06, and a thickness of 40nm. The P-type semiconductor layer is a P-type GaN layer with a thickness of 180nm and a Mg doping concentration of 5×10 20 cm -3 .

[0053] Example 2 This embodiment provides a light-emitting diode epitaxial wafer, which differs from the first embodiment in that: In α Ga 1-α The N layer is doped with Mg at a concentration of 2.5×10 19 cm -3 ;In β Ga 1-β The N layer is doped with Mg; the doping concentration is 3.5×10 18 cm -3 .

[0054] The rest are the same as in Example 1.

[0055] Example 3 This embodiment provides a light-emitting diode epitaxial wafer, which differs from the second embodiment in that: 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.

[0056] The rest are the same as in Example 2.

[0057] Example 4 This embodiment provides a light-emitting diode epitaxial wafer, which differs from the third embodiment in that: The first GaN layer is doped with Si, and its doping concentration is 5.4×10 17 cm -3 .

[0058] The rest are the same as in Example 3.

[0059] Example 5 This embodiment is a light-emitting diode epitaxial wafer, which differs from the embodiment 4 in that: The fourth GaN layer is doped with Mg, and its doping concentration is 5.2×10 18 cm -3 .

[0060] The rest are the same as in Example 4.

[0061] Comparative Example 1 This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that: The first hole injection enhancement layer and the second hole injection enhancement layer are not included.

[0062] The rest are the same as in Example 1.

[0063] Comparative Example 2 This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that: The third multi-quantum well layer, the second hole injection enhancement layer, the second multi-quantum well layer, the first hole injection enhancement layer and the first multi-quantum well layer are sequentially stacked on the N-type semiconductor layer.

[0064] The rest are the same as in Example 1.

[0065] Comparative Example 3 This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that: A first multi-quantum well layer, a second hole injection enhancement layer, a second multi-quantum well layer, a first hole injection enhancement layer and a third multi-quantum well layer are sequentially stacked on the N-type semiconductor layer.

[0066] The rest are the same as in Example 1.

[0067] Comparative Example 4 This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that: does not contain a first hole injection enhancement layer; The rest are the same as in Example 1.

[0068] Comparative Example 5 This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that: No second hole injection enhancement layer is included.

[0069] The rest are the same as in Example 1.

[0070] The light-emitting diode epitaxial wafers obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were made into 10 mil×24 mil chips, and their brightness at 200 mA was tested. The brightness improvement rate was calculated based on the data of Comparative Example 1.

[0071] 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 following table:

[0072] The above is a preferred embodiment of the invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A light-emitting diode epitaxial wafer, characterized in that: It includes 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 sequentially stacked on the substrate; The first multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In x Ga 1-x N layer and a first GaN layer; the emission wavelength of the first multi-quantum well layer is λ1; The first hole injection enhancement layer is a periodic structure, and each period includes sequentially stacked In α Ga 1-α N layer and In a Al b Ga 1-a-b N-layer; The second multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In y Ga 1-y N layer and a second GaN layer; the emission wavelength of the second multi-quantum well layer is λ2; The second hole injection enhancement layer is a periodic structure, each period includes sequentially stacked In β Ga 1-β N layer and a third GaN layer; The third multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In z Ga 1-z N layer and a fourth GaN layer; the emission wavelength of the third multi-quantum well layer is λ3; Among them, α<β<x<y<z, α≥a, λ1<λ2≤λ3.

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

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

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

6. The light emitting diode epitaxial wafer according to claim 5, wherein: In α Ga 1-α The Mg doping concentration of the N layer is 3.2×10 18 cm -3 ~5.6×10 19 cm -3 ; In β Ga 1-β The Mg doping concentration of the N layer is 1.4×10 18 cm -3 ~2.8×10 19 cm -3 .

7. The light emitting diode epitaxial wafer according to 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 according to claim 1, wherein: The first GaN layer is doped with Si, and the Si doping concentration is 1.8×10 17 cm -3 ~7.6×10 17 cm -3 .

9. The light emitting diode epitaxial wafer according to claim 1, wherein: The fourth GaN layer is doped with Mg, and the Mg doping concentration is 3.2×10 18 cm -3 ~2.6×10 19 cm -3 .

10. A light emitting diode, characterized in that: It comprises the light emitting diode epitaxial wafer according to any one of claims 1 to 9.

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