Light-emitting diode epitaxial wafer and light-emitting diode

Abstract

The present invention discloses a light emitting diode epitaxial wafer and a light emitting diode, which relate to the field of optoelectronic devices. The epitaxial wafer comprises a first multi-quantum well layer, a second multi-quantum well layer, a third multi-quantum well layer, an end well layer (In z Ga 1‑z N layer), the last barrier layer (the fourth GaN layer); the first multi-quantum well layer includes In w Ga 1‑w N layer, Al a Ga 1‑a N layer, first Si-doped GaN layer, Al b Ga 1‑b N layer and the first GaN layer; the second multi-quantum well layer includes In x Ga 1‑x N layer, Al c Ga 1‑c N layer, second Si-doped GaN layer, Al d Ga 1‑d N layer and the second GaN layer; the third multi-quantum well layer includes In y Ga 1‑y N layer, Al α Ga 1‑α N layer, the third Si-doped GaN layer, Al β Ga 1‑β N layer and the third GaN layer; w>x>y≥z, a≥c≥α, b≥d≥β. Implementation of the present invention can improve luminous efficiency.

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] Common LED lighting uses a combination of blue LED chips and yellow and red phosphors. However, this type of LED light spectrum has a high proportion of blue light, which poses a significant risk to eyesight, and its color rendering performance is poor. New full-spectrum lighting is a lighting technology that simulates the spectrum of natural light. Current methods for achieving this are: 1. Mixing multiple LED light sources with different wavelengths, such as blue, green, and red LEDs. However, these chips have varying performance and lifespans, making control complex and costly. 2. Using multiple phosphors for conversion, such as using a purple LED chip to excite red, green, and blue phosphors. This method is low-cost, but has low luminous efficiency and severe phosphor aging. However, achieving full-spectrum lighting by using a single LED chip to generate light of different primary colors, which in turn excites different phosphors, would significantly extend lamp life and reduce costs, which is of great significance. On the other hand, different luminescence wavelengths mean that the multi-quantum well region needs to be designed with quantum well layers and quantum barrier layers of different components, which often means that the stress between the wells and barriers increases and the defects increase, resulting in lower radiative recombination efficiency and lower luminescence efficiency. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a light emitting diode epitaxial wafer, which can improve the light emitting efficiency of the light emitting diode.

[0004] Another technical problem to be solved by the present invention is to provide a light emitting diode.

[0005] 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 second multi-quantum well layer, a third multi-quantum well layer, a last well layer, a last barrier layer and a P-type semiconductor layer sequentially stacked on the substrate;

[0006] The first multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In w Ga 1-w N layer, Al a Ga 1-a N layer, first Si-doped GaN layer, Al b Ga 1-b N layer and a first GaN layer; the emission wavelength of the first multi-quantum well layer is λ1;

[0007] The second multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In xGa 1-x N layer, Al c Ga 1-c N layer, second Si-doped GaN layer, Al d Ga 1-d N layer and a second GaN layer; the emission wavelength of the second multi-quantum well layer is λ2;

[0008] The third multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In y Ga 1-y N layer, Al α Ga 1-α N layer, the third Si-doped GaN layer, Al β Ga 1-β N layer and a third GaN layer; the emission wavelength of the third multi-quantum well layer is λ3;

[0009] The final well layer is In z Ga 1-z N layer, the final barrier layer is a fourth GaN layer; the emission wavelength of the final well layer is λ4;

[0010] Where w>x>y≥z, so that λ1>λ2>λ3≥λ4;

[0011] a≥c≥α, b≥d≥β.

[0012] As an improvement to the above technical solution, the Si doping concentration of the first Si-doped GaN layer is greater than the Si doping concentration of the second Si-doped GaN layer;

[0013] The Si doping concentration of the second Si-doped GaN layer is greater than the Si doping concentration of the third Si-doped GaN layer.

[0014] As an improvement to the above technical solution, the number of periods of the first multi-quantum well layer is 1 to 5; its emission wavelength is 490 nm to 500 nm; and / or

[0015] In w Ga 1-w The value of w in the N layer ranges from 0.19 to 0.21, and its thickness ranges from 2 nm to 5 nm; and / or

[0016] The Al a Ga 1-a The value of a in the N layer ranges from 0.03 to 0.28, and its thickness ranges from 0.3 nm to 2.5 nm; and / or

[0017] The Si doping concentration of the first Si-doped GaN layer is 3.5×10 17 cm -3 ~1×10 18 cm-3 , the thickness of which is 0.8nm~8nm; and / or

[0018] The Al b Ga 1-b The value of b in the N layer ranges from 0.03 to 0.28, and its thickness ranges from 0.3 nm to 2.5 nm; and / or

[0019] The thickness of the first GaN layer is 5 nm to 16 nm; and / or

[0020] The number of periods of the second multi-quantum well layer is 2 to 6; the emission wavelength is 445 nm to 480 nm; and / or

[0021] In x Ga 1-x The value of x in the N layer ranges from 0.13 to 0.19, and its thickness ranges from 2 nm to 5 nm; and / or

[0022] The Al c Ga 1-c The value of c in the N layer ranges from 0.02 to 0.21, and its thickness ranges from 0.3 nm to 2.5 nm; and / or

[0023] The Si doping concentration of the second Si-doped GaN layer is 2.5×10 17 cm -3 ~8×10 17 cm -3 , the thickness of which is 0.8nm~8nm; and / or

[0024] The Al d Ga 1-d The value of d in the N layer ranges from 0.02 to 0.21, and its thickness ranges from 0.3 nm to 2.5 nm; and / or

[0025] The thickness of the second GaN layer is 5 nm to 16 nm; and / or

[0026] The period number of the third multi-quantum well layer is 2 to 5; the emission wavelength is 430 nm to 445 nm; and / or

[0027] In y Ga 1-y The value of y in the N layer ranges from 0.1 to 0.13, and its thickness is from 2 nm to 5 nm; and / or

[0028] The Al α Ga 1-α The value of α in the N layer ranges from 0.01 to 0.12, and its thickness ranges from 0.3 nm to 2.5 nm; and / or

[0029] The Si doping concentration of the third Si-doped GaN layer is 2×10 17 cm -3 ~7.5×10 17 cm -3 , the thickness of which is 0.8nm~8nm; and / or

[0030] The Al β Ga 1-β The value of β in the N layer ranges from 0.01 to 0.12, and its thickness ranges from 0.3 nm to 2.5 nm; and / or

[0031] The thickness of the third GaN layer is 5 nm to 16 nm; and / or

[0032] In z Ga 1-z The value of z in the N layer ranges from 0.1 to 0.13, its thickness ranges from 2 nm to 5 nm, and its emission wavelength ranges from 430 nm to 445 nm; and / or

[0033] The thickness of the last barrier layer is 5nm-20nm.

[0034] As an improvement to the above technical solution, the first GaN layer, the second GaN layer, and the third GaN layer are all doped with Si, and the fourth GaN layer is an unintentionally doped GaN layer;

[0035] The Si doping concentration of the first GaN layer is greater than the Si doping concentration of the second GaN layer, and the Si doping concentration of the second GaN layer is greater than the Si doping concentration of the third GaN layer.

[0036] As an improvement to the above technical solution, the Si doping concentration of the first GaN layer is 2.5×10 17 cm -3 ~9×10 17 cm -3 and / or

[0037] The Si doping concentration of the second GaN layer is 1.8×10 17 cm -3 ~7×10 17 cm -3 and / or

[0038] The Si doping concentration of the third GaN layer is 1.2×10 17 cm -3 ~6×10 17 cm -3 .

[0039] As an improvement to the above technical solution, the end well layer is doped with Mg, and the doping concentration is 3×1018 cm -3 ~8×10 19 cm -3 .

[0040] As an improvement of the above technical solution, it further includes a transition well layer and a transition barrier layer sequentially stacked between the third multi-quantum well layer and the final well layer;

[0041] The transition well layer is In u Ga 1-u N layer, wherein the value of u ranges from 0.1 to 0.13, and the thickness of the transition well layer is from 2 nm to 5 nm; and / or

[0042] The transition barrier layer is a fifth GaN layer, and its thickness is 5 nm to 20 nm.

[0043] As an improvement of the above technical solution, it further includes a hole regulation layer provided between the last well layer and the last barrier layer;

[0044] The hole control layer is a periodic structure, and each period includes a Mg-doped InGaN layer and an Al-doped InGaN layer stacked in sequence. γ Ga 1-γ N-layer;

[0045] Among them, γ≤β.

[0046] As an improvement to the above technical solution, the number of periods of the hole regulation layer is 2 to 10; and / or

[0047] The ratio of In component in the Mg-doped InGaN layer is 0.01~0.09, and the Mg doping concentration is 2×10 18 cm -3 ~6.5×10 19 cm -3 , the thickness of which is 0.3nm~2.5nm; and / or

[0048] The Al γ Ga 1-γ The value range of γ in the N layer is 0.01~0.07, and its thickness is 0.5nm~2.5nm.

[0049] Correspondingly, the present invention also discloses a light emitting diode, which includes the light emitting diode epitaxial wafer mentioned above.

[0050] The implementation of the present invention has the following beneficial effects:

[0051] The light emitting diode epitaxial wafer in one embodiment of the present invention comprises a first multi-quantum well layer, a second multi-quantum well layer, a third multi-quantum well layer, a final well layer and a final barrier layer, wherein the first multi-quantum well layer comprises In w Ga1-w N layer, Al a Ga 1-a N layer, first Si-doped GaN layer, Al b Ga 1-b N layer and the first GaN layer; its emission wavelength is λ1; the second multi-quantum well layer includes In x Ga 1-x N layer, Al c Ga 1-c N layer, second Si-doped GaN layer, Al d Ga 1-d N layer and the second GaN layer; its emission wavelength is λ2; the third multi-quantum well layer includes In y Ga 1-y N layer, Al α Ga 1-α N layer, the third Si-doped GaN layer, Al β Ga 1-β N layer and the third GaN layer; its emission wavelength is λ3; the end well layer is In z Ga 1-z N layer, the last barrier layer is the fourth GaN layer; the emission wavelength of the last well layer is λ4, w>x>y≥z, so that λ1>λ2>λ3≥λ4; a≥c≥α, b≥d≥β. Based on the above-mentioned light-emitting diode epitaxial wafer, firstly, since the In component in the quantum well with a larger wavelength is lower and the growth temperature is higher, by adopting a growth sequence with decreasing emission wavelengths, a quantum well with a high In component can be formed first, and then a quantum well with a low In component can be formed, thereby improving the crystal quality of the previously grown multi-quantum well layer in the subsequent high-temperature growth process, improving the crystal quality of the overall light-emitting diode epitaxial wafer, improving the radiation recombination efficiency, and improving the luminescence efficiency. Secondly, by introducing Al into the first multi-quantum well layer a Ga 1-a N layer, first Si-doped GaN layer and Al b Ga 1-b The N layer can reduce the electron mobility and weaken the polarization electric field, thereby increasing the recombination probability of electrons and holes and improving the luminous efficiency. c Ga 1-c N layer, the second Si-doped GaN layer and Al d Ga 1-d N layer, Al introduced into the third multi-quantum well layer α Ga 1-α N layer, the third Si-doped GaN layer, Al β Ga 1-βThe N layer also has a similar effect. Thirdly, by controlling a≥c≥α, b≥d≥β, the height of the barrier in the first multi-quantum well layer can be made greater than the height of the barrier in the second multi-quantum well layer and greater than the height of the barrier in the third multi-quantum well layer, so that holes can be better injected into the multi-quantum well structure closer to the N-type semiconductor layer, optimizing the radiative recombination efficiency. In addition, introducing AlGaN material with a high Al content as an intermediate layer in the multi-quantum well with a higher In content can also weaken the piezoelectric polarization effect, increase the overlap rate of electron and hole wave functions, and improve the luminous efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 1 is a schematic structural diagram of a light emitting diode epitaxial wafer according to an embodiment of the present invention;

[0053] Figure 2 is a schematic structural diagram of a first multi-quantum well layer in one embodiment of the present invention;

[0054] Figure 3 is a schematic structural diagram of a second multi-quantum well layer in one embodiment of the present invention;

[0055] Figure 4 is a schematic structural diagram of a third multi-quantum well layer in one embodiment of the present invention;

[0056] Figure 5 It is a structural schematic diagram of a light emitting diode epitaxial wafer in another embodiment of the present invention. DETAILED DESCRIPTION

[0057] 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.

[0058] See also Figures 1 to 4 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 second multi-quantum well layer 400, a third multi-quantum well layer 500, a last well layer 610, a last barrier layer 620 and a P-type semiconductor layer 700 stacked in sequence on the substrate 100.

[0059] The first multi-quantum well layer 300 is a periodic structure, and each period includes sequentially stacked In w Ga 1-w N layer 310, Al a Ga 1-a N layer 320, first Si-doped GaN layer 330, Al b Ga 1-b N layer 340 and first GaN layer 350; the emission wavelength of the first multi-quantum well layer 300 is λ1;

[0060] The second multi-quantum well layer 400 is a periodic structure, and each period includes sequentially stacked In x Ga 1-x N layer 410, Al c Ga 1-c N layer 420, second Si-doped GaN layer 430, Al d Ga 1-d N layer 440 and second GaN layer 450; the light emission wavelength of the second multi-quantum well layer 400 is λ2;

[0061] The third multi-quantum well layer 500 is a periodic structure, and each period includes sequentially stacked In y Ga 1-y N layer 510, Al α Ga 1-α N layer 520, third Si-doped GaN layer 530, Al β Ga 1-β N layer 540 and third GaN layer 550; the emission wavelength of the third multi-quantum well layer 500 is λ3;

[0062] The final well layer 610 is In z Ga 1-z N layer, the last barrier layer 620 is a fourth GaN layer; the emission wavelength of the last well layer 610 is λ4;

[0063] Among them, w>x>y≥z, so that λ1>λ2>λ3≥λ4; a≥c≥α, b≥d≥β.

[0064] Based on the above-mentioned light-emitting diode epitaxial wafer, firstly, since the In content in the quantum well with a larger wavelength is lower and the growth temperature is higher, by adopting a growth sequence with decreasing luminous wavelength, a quantum well with a high In content can be formed first, and then a quantum well with a low In content can be formed, thereby improving the crystal quality of the preceding multi-quantum well layer in the subsequent high-temperature growth process, improving the crystal quality of the entire light-emitting diode epitaxial wafer, improving the radiation recombination efficiency, and improving the luminous efficiency. Secondly, by introducing Al into the first multi-quantum well layer 300, the luminous efficiency of the light-emitting diode epitaxial wafer is improved. a Ga 1-a N layer 320, first Si-doped GaN layer 330 and Al b Ga 1-b The N layer 340 can reduce the electron mobility and weaken the polarization electric field, thereby increasing the recombination probability of electrons and holes and improving the luminous efficiency. c Ga 1-c N layer 420, second Si-doped GaN layer 430 and Al d Ga 1-d The Al introduced into the N layer 440 and the third multi-quantum well layer 500 α Ga1-α N layer 520, third Si-doped GaN layer 530, Al β Ga 1-β The N-type layer 540 also has a similar effect. By controlling a ≥ c ≥ α and b ≥ d ≥ β, the height of the potential barrier in the first multi-quantum well layer 300 can be made greater than the height of the potential barrier in the second multi-quantum well layer 400 and greater than the height of the potential barrier in the third multi-quantum well layer 500. This allows holes to be better injected into the multi-quantum well structure closer to the N-type semiconductor layer 200, optimizing the radiative recombination efficiency. Furthermore, introducing a high-Al content AlGaN material as an intermediate layer in the multi-quantum well with a higher In content can further weaken the piezoelectric polarization effect, increase the overlap rate of electron and hole wave functions, and improve luminescence efficiency.

[0065] Specifically, in some embodiments, the period number of the first multi-quantum well layer 300 is 1 to 6, preferably 1 to 5. The light emission wavelength of the first multi-quantum well layer 300 is 490 nm to 500 nm, which belongs to the cyan wavelength range.

[0066] Specifically, in some embodiments, w Ga 1-w The value range of w in the N layer 310 is 0.18~0.22, preferably 0.19~0.21. w Ga 1-w The thickness of the N layer 310 is 2 nm to 5 nm, preferably 2.05 nm to 4.85 nm.

[0067] Specifically, in some embodiments, Al a Ga 1-a The value range of a in the N layer 320 is 0.01-0.28, preferably 0.03-0.28, and more preferably 0.12-0.25. a Ga 1-a The thickness of the N layer 320 is 0.3 nm to 3 nm, preferably 0.3 nm to 2.5 nm.

[0068] Specifically, in some embodiments, the Si doping concentration of the first Si-doped GaN layer 330 is 3×10 17 cm -3 ~1×10 18 cm -3 , preferably 3.5×10 17 cm -3 ~1×10 18 cm -3The free electrons provided by Si doping can reduce the polarization electric field strength through the Coulomb screening effect, increase the electron-hole wave function overlap rate, and improve the luminous efficiency. The thickness of the first Si-doped GaN layer 330 is 0.8nm to 10nm, preferably 0.8nm to 8nm, and more preferably 1nm to 5nm.

[0069] Specifically, in some embodiments, Al b Ga 1-b The value range of b in the N layer 340 is 0.01~0.28, preferably 0.03~0.28, and more preferably 0.12~0.25. b Ga 1-b The thickness of the N layer 340 is 0.3 nm to 3 nm, preferably 0.3 nm to 2.5 nm.

[0070] Al a Ga 1-a N layer 320, first Si-doped GaN layer 330 and Al b Ga 1-b The combination of non-doped-Si-doped-non-doped, high potential barrier-low potential barrier-high potential barrier formed by the N layer 340 is more conducive to weakening the polarization electric field generated between the well barriers.

[0071] Specifically, in some embodiments, the thickness of the first GaN layer 350 is 5 nm to 20 nm, preferably 5 nm to 16 nm.

[0072] Specifically, in some embodiments, the period number of the second multi-quantum well layer 400 is 1 to 6, preferably 2 to 6. The light emission wavelength of the second multi-quantum well layer 400 is 445 nm to 480 nm, which belongs to the blue light band.

[0073] Specifically, in some embodiments, x Ga 1-x The value range of x in the N layer 410 is 0.12~0.2, preferably 0.13~0.19. x Ga 1-x The thickness of the N layer 410 is 2 nm to 5 nm, preferably 2.1 nm to 4.9 nm.

[0074] Specifically, in some embodiments, Al c Ga 1-c The value range of c in the N layer 420 is 0.01-0.28, preferably 0.02-0.21, and more preferably 0.1-0.2. c Ga 1-c The thickness of the N layer 420 is 0.3 nm to 3 nm, preferably 0.3 nm to 2.5 nm.

[0075] Specifically, in some embodiments, the Si doping concentration of the second Si-doped GaN layer 430 is 2×10 17 cm -3 ~8×10 17 cm -3 , preferably 2.5×10 17 cm -3 ~8×10 17 cm -3 The thickness of the second Si-doped GaN layer 430 is 0.8 nm to 10 nm, preferably 0.8 nm to 8 nm, and more preferably 1 nm to 5 nm.

[0076] Specifically, in some embodiments, Al d Ga 1-d The value range of d in the N layer 440 is 0.01-0.28, preferably 0.02-0.21, and more preferably 0.1-0.2. d Ga 1-d The thickness of the N layer 440 is 0.3 nm to 3 nm, preferably 0.3 nm to 2.5 nm.

[0077] Specifically, in some embodiments, the thickness of the second GaN layer 450 is 5 nm to 20 nm, preferably 5 nm to 16 nm.

[0078] Specifically, in some embodiments, the period number of the third multi-quantum well layer 500 is 1 to 5, preferably 2 to 5. The light emission wavelength of the third multi-quantum well layer 500 is 430 nm to 445 nm, which belongs to the violet band.

[0079] Specifically, in some embodiments, y Ga 1-y The value range of y in the N layer 510 is 0.08~0.13, preferably 0.1~0.13. y Ga 1-y The thickness of the N layer 510 is 2 nm to 5 nm, preferably 2.07 nm to 4.86 nm.

[0080] Specifically, in some embodiments, Al α Ga 1-α The value range of α in the N layer 520 is 0.01-0.2, preferably 0.01-0.12. α Ga 1-α The thickness of the N layer 520 is 0.3 nm to 3 nm, preferably 0.3 nm to 2.5 nm.

[0081] Specifically, in some embodiments, the Si doping concentration of the third Si-doped GaN layer 530 is 2×10 17 cm -3 ~8×10 17 cm -3 , preferably 2×10 17 cm -3 ~7.5×10 17 cm -3 The thickness of the third Si-doped GaN layer 530 is 0.8 nm to 10 nm, preferably 0.8 nm to 8 nm.

[0082] Specifically, in some embodiments, Al β Ga 1-β The value range of β in the N layer 540 is 0.01~0.2, preferably 0.01~0.12. β Ga 1-β The thickness of the N layer 540 is 0.3 nm to 3 nm, preferably 0.3 nm to 2.5 nm.

[0083] Specifically, in some embodiments, the thickness of the third GaN layer 550 is 5 nm to 20 nm, preferably 5 nm to 16 nm.

[0084] Specifically, in some embodiments, the end well layer 610 (ie, In z Ga 1-z The value of z in the N layer is in the range of 0.08 to 0.13, preferably 0.1 to 0.13. The thickness of the end well layer 610 is 2 nm to 5 nm, and the emission wavelength is 430 nm to 445 nm.

[0085] Specifically, in some embodiments, the thickness of the last barrier layer 620 is 5 nm to 20 nm.

[0086] Specifically, in some embodiments, the substrate 100 is a sapphire substrate, a silicon substrate, or a carbonized substrate, but is not limited thereto. Preferably, it is a sapphire substrate.

[0087] 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.

[0088] Specifically, in some embodiments, the P-type semiconductor layer 700 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 ~5×1020 cm -3 .

[0089] 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 800. The buffer layer 110 and the undoped GaN layer 120 are sequentially arranged 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 800 is arranged between the last barrier layer 620 and the P-type semiconductor layer 700, and is an AlInGaN layer or an AlGaN layer, but is not limited thereto. Preferably, it is an AlInGaN layer, the Al component ratio of which is 0.01 to 0.1, the In component ratio of which is 0.01 to 0.2, and the thickness of which is 10 nm to 50 nm.

[0090] Preferably, in some embodiments, the Si doping concentration of the first Si-doped GaN layer 330 is greater than the Si doping concentration of the second Si-doped GaN layer 430, and greater than the Si doping concentration of the third Si-doped GaN layer 530. This embodiment effectively weakens the polarization field and improves luminous efficiency while also ensuring a stable luminous wavelength and enhancing color purity.

[0091] Preferably, in some embodiments, the first GaN layer 350, the second GaN layer 450, and the third GaN layer 550 are all doped with Si, and the Si doping concentration of the first GaN layer 350 is greater than the Si doping concentration of the second GaN layer 450, and greater than the Si doping concentration of the third GaN layer 550. The fourth GaN layer is an unintentionally doped GaN layer; through these doping methods, the polarization electric field can be further weakened, thereby improving the luminous efficiency; and the matching degree of electrons and holes in each quantum well layer can also be optimized, thereby improving the luminous efficiency. More specifically, the Si doping concentration of the first GaN layer 350 is 2.5×10 17 cm -3 ~9×10 17 cm -3 The Si doping concentration of the second GaN layer 450 is 1.8×10 17 cm -3 ~7×10 17 cm -3 The Si doping concentration of the third GaN layer 550 is 1.2×10 17 cm -3 ~6×10 17 cm -3 .

[0092] Preferably, in some embodiments, the end well layer 610 is doped with Mg at a doping concentration of 3×1018 cm -3 ~8×10 19 cm -3 By doping Mg into the final well layer 610 , the holes in the quantum well region can be supplemented, further improving the luminous efficiency.

[0093] Preferably, see Figure 5 In some embodiments, after Mg doping is introduced into the final well layer 610, a transition well layer 640 and a transition barrier layer 650 are introduced between the third multi-quantum well layer 500 and the final well layer 610; this can effectively prevent the degradation of crystal quality caused by Mg doping. More specifically, the transition well layer 640 is In u Ga 1-u N layer, wherein y≥u≥z, preferably y=u=z. The value of u ranges from 0.1 to 0.13. The thickness of the transition well layer 640 is 2nm to 5nm. The transition barrier layer 650 is the fifth GaN layer, and its thickness is 5nm to 20nm.

[0094] Preferably, in some embodiments, a hole control layer 630 is further provided between the final well layer 610 and the final barrier layer 620; the hole control layer 630 is a periodic structure, and each period includes a sequentially stacked Mg-doped InGaN layer 631 and an Al-doped InGaN layer 632. γ Ga 1-γ N layer 632; wherein γ≤β. This hole control layer 630 can further improve the efficiency of hole injection into the multi-quantum well region and improve the luminous efficiency. More specifically, the number of periods of the hole control layer 630 is 2 to 10; the ratio of In component in the Mg-doped InGaN layer 631 is 0.01 to 0.09, and the Mg doping concentration is 2×10 18 cm -3 ~6.5×10 19 cm -3 , its thickness is 0.3nm~2.5nm; Al γ Ga 1-γ The value range of γ in the N layer 632 is 0.01-0.07, and the thickness thereof is 0.5 nm-2.5 nm.

[0095] Correspondingly, the present invention also discloses a light emitting diode, which includes the light emitting diode epitaxial wafer mentioned above.

[0096] The present invention will be further described below with specific embodiments:

[0097] Example 1

[0098] 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 second multi-quantum well layer, a third multi-quantum well layer, a last well layer, a last barrier layer, an electron blocking layer, and a P-type semiconductor layer stacked sequentially on the substrate;

[0099] 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 2.5 μm. The N-type semiconductor layer is an N-type GaN layer with a Si doping concentration of 8×10 18 cm -3 , with a thickness of 3μm.

[0100] The first multi-quantum well layer is a periodic structure with 3 periods, and each period includes sequentially stacked In w Ga 1-w N layer (w=0.2), Al a Ga 1-a N layer (a=0.2), first Si-doped GaN layer, Al b Ga 1-b N layer (b = 0.2) and the first GaN layer; In w Ga 1-w The thickness of the N layer is 3.5nm, and the Al a Ga 1-a The thickness of the N layer is 1.5 nm, and the Si doping concentration of the first Si-doped GaN layer is 4×10 17 cm -3 , its thickness is 4nm; Al b Ga 1-b The thickness of the N layer is 1.5 nm, and the thickness of the first GaN layer is 10 nm.

[0101] The second multi-quantum well layer is a periodic structure with 3 periods, and each period includes sequentially stacked In x Ga 1-x N layer (x=0.15), Al c Ga 1-c N layer (c=0.15), second Si-doped GaN layer, Al d Ga 1-d N layer (d = 0.15) and the second GaN layer; In x Ga 1-x The thickness of the N layer is 3.5nm, and the Al c Ga 1-c The thickness of the N layer is 1.2 nm, and the Si doping concentration of the second Si-doped GaN layer is 4×10 17 cm -3 , its thickness is 4nm; Al d Ga 1-dThe thickness of the N layer is 1.2 nm, and the thickness of the second GaN layer is 10 nm.

[0102] The third multi-quantum well layer is a periodic structure with 3 periods, and each period includes sequentially stacked In y Ga 1-y N layer (y=0.12), Al α Ga 1-α N layer (α=0.08), the third Si-doped GaN layer, Al β Ga 1-β N layer (β = 0.08) and the third GaN layer; In y Ga 1-y The thickness of the N layer is 3nm, and the Al α Ga 1-α The thickness of the N layer is 1 nm, and the Si doping concentration of the third Si-doped GaN layer is 4×10 17 cm -3 , its thickness is 4nm; Al β Ga 1-β The thickness of the N layer is 1 nm, and the thickness of the third GaN layer is 10 nm.

[0103] Among them, the end well layer is In z Ga 1-z The N layer (z=0.12) has a thickness of 3.5 nm. The final barrier layer is the fourth GaN layer, which has a thickness of 12 nm.

[0104] The electron blocking layer is an AlInGaN layer with an Al component ratio of 0.03, an In component ratio of 0.08, and a thickness of 35nm. The P-type semiconductor layer is a P-type GaN layer with a thickness of 180nm and a Mg doping concentration of 3×10 20 cm -3 .

[0105] Example 2

[0106] This embodiment provides a light-emitting diode epitaxial wafer, which differs from the first embodiment in that:

[0107] The Si doping concentration of the first Si-doped GaN layer is 6×10 17 cm -3 The Si doping concentration of the second Si-doped GaN layer is 4×10 17 cm -3 The Si doping concentration of the third Si-doped GaN layer is 2.5×10 17 cm -3 .

[0108] The rest are the same as in Example 1.

[0109] Example 3

[0110] This embodiment provides a light-emitting diode epitaxial wafer, which differs from the second embodiment in that:

[0111] The first GaN layer, the second GaN layer, and the third GaN layer are all doped with Si. The Si doping concentration of the first GaN layer is 8.2×10 17 cm -3 , the Si doping concentration of the second GaN layer is 5.5×10 17 cm -3 , the Si doping concentration of the third GaN layer is 3×10 17 cm -3 .

[0112] The rest are the same as in Example 2.

[0113] Example 4

[0114] This embodiment provides a light-emitting diode epitaxial wafer, which differs from the third embodiment in that:

[0115] A transition well layer and a transition barrier layer are sequentially stacked between the third multi-quantum well layer and the final well layer;

[0116] The transition well layer is In u Ga 1-u The N layer (u=0.12) has a thickness of 3.5 nm. The transition barrier layer is the fifth GaN layer, which is a non-intentionally doped structure and has a thickness of 12 nm.

[0117] The end well layer is doped with Mg, and the doping concentration is 8×10 18 cm -3 .

[0118] The rest are the same as in Example 3.

[0119] Example 5

[0120] This embodiment provides a light-emitting diode epitaxial wafer, which differs from the fourth embodiment in that:

[0121] A hole control layer is provided between the final well layer and the final barrier layer. The hole control layer is a periodic structure with 8 periods. Each period includes a sequentially stacked Mg-doped InGaN layer and an Al γ Ga 1-γ N layer (γ = 0.05); the proportion of In component in the Mg-doped InGaN layer is 0.04, and the Mg doping concentration is 5.5×10 19 cm -3 , its thickness is 1.5nm; Al γ Ga 1-γ The thickness of the N layer is 2.5 nm.

[0122] The rest are the same as in Example 4.

[0123] Comparative Example 1

[0124] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that:

[0125] The first multi-quantum well layer does not include Al a Ga 1-a N layer, first Si-doped GaN layer and Al b Ga 1-b N layer, the second multi-quantum well layer does not include Al c Ga 1-c N layer, the second Si-doped GaN layer and Al d Ga 1-d N layer, the third multi-quantum well layer does not include Al α Ga 1-α N layer, the third Si-doped GaN layer and Al β Ga 1-β N layers.

[0126] The rest are the same as in Example 1.

[0127] Comparative Example 2

[0128] This comparative example provides a light-emitting diode epitaxial wafer, which differs from Example 1 in that:

[0129] The last well layer and the last barrier layer are not included.

[0130] The rest are the same as in Example 1.

[0131] Comparative Example 3

[0132] This comparative example provides a light-emitting diode epitaxial wafer, which differs from comparative example 1 in that:

[0133] The following are arranged in sequence between the N-type semiconductor layer and the P-type semiconductor layer: a third multi-quantum well layer, a second multi-quantum well layer, a first multi-quantum well layer, a last well layer and a last barrier layer.

[0134] The rest are the same as Comparative Example 1.

[0135] The light-emitting diode epitaxial wafers obtained in Examples 1 to 5 and Comparative Examples 1 to 3 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.

[0136] 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:

[0137]

[0138] 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: The method comprises a substrate, an N-type semiconductor layer, a first multi-quantum well layer, a second multi-quantum well layer, a third multi-quantum well layer, a last well layer, a last barrier layer, an electron blocking 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 w Ga 1-w N layer, Al a Ga 1-a N layer, first Si-doped GaN layer, Al b Ga 1-b N layer and a first GaN layer; the emission wavelength of the first multi-quantum well layer is λ1; the first GaN layer is doped with Si; The second multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In x Ga 1-x N layer, Al c Ga 1-c N layer, second Si-doped GaN layer, Al d Ga 1-d N layer and a second GaN layer; the emission wavelength of the second multi-quantum well layer is λ2; the second GaN layer is doped with Si; The third multi-quantum well layer is a periodic structure, and each period includes sequentially stacked In y Ga 1-y N layer, Al α Ga 1-α N layer, the third Si-doped GaN layer, Al β Ga 1-β N layer and a third GaN layer; the emission wavelength of the third multi-quantum well layer is λ3; the third GaN layer is doped with Si; The final well layer is In z Ga 1-z N layer, the final barrier layer is a fourth GaN layer; the emission wavelength of the final well layer is λ4; the fourth GaN layer is an undoped GaN layer; The electron blocking layer is an AlInGaN layer, wherein the Al component accounts for 0.01-0.1 and the In component accounts for 0.01-0.2; Where w>x>y≥z, so that λ1>λ2>λ3≥λ4; a≥c≥α, b≥d≥β.

2. The light emitting diode epitaxial wafer according to claim 1, wherein: The Si doping concentration of the first Si-doped GaN layer is greater than the Si doping concentration of the second Si-doped GaN layer; The Si doping concentration of the second Si-doped GaN layer is greater than the Si doping concentration of the third Si-doped GaN layer.

3. The light emitting diode epitaxial wafer according to claim 1, wherein: The period number of the first multi-quantum well layer is 1 to 5; the emission wavelength is 490 nm to 500 nm; and / or In w Ga 1-w The value of w in the N layer ranges from 0.19 to 0.21, and its thickness ranges from 2 nm to 5 nm; and / or The Al a Ga 1-a The value of a in the N layer ranges from 0.03 to 0.28, and its thickness ranges from 0.3 nm to 2.5 nm; and / or The Si doping concentration of the first Si-doped GaN layer is 3.5×10 17 cm -3 ~1×10 18 cm -3 , the thickness of which is 0.8nm~8nm; and / or The Al b Ga 1-b The value of b in the N layer ranges from 0.03 to 0.28, and its thickness ranges from 0.3 nm to 2.5 nm; and / or The thickness of the first GaN layer is 5 nm to 16 nm; and / or The number of periods of the second multi-quantum well layer is 2 to 6; the emission wavelength is 445 nm to 480 nm; and / or In x Ga 1-x The value of x in the N layer ranges from 0.13 to 0.19, and its thickness ranges from 2 nm to 5 nm; and / or The Al c Ga 1-c The value of c in the N layer ranges from 0.02 to 0.21, and its thickness ranges from 0.3 nm to 2.5 nm; and / or The Si doping concentration of the second Si-doped GaN layer is 2.5×10 17 cm -3 ~8×10 17 cm -3 , the thickness of which is 0.8nm~8nm; and / or The Al d Ga 1-d The value of d in the N layer ranges from 0.02 to 0.21, and its thickness ranges from 0.3 nm to 2.5 nm; and / or The thickness of the second GaN layer is 5 nm to 16 nm; and / or The period number of the third multi-quantum well layer is 2 to 5; the emission wavelength is 430 nm to 445 nm; and / or In y Ga 1-y The value of y in the N layer ranges from 0.1 to 0.13, and its thickness is from 2 nm to 5 nm; and / or The Al α Ga 1-α The value of α in the N layer ranges from 0.01 to 0.12, and its thickness ranges from 0.3 nm to 2.5 nm; and / or The Si doping concentration of the third Si-doped GaN layer is 2×10 17 cm -3 ~7.5×10 17 cm -3 , the thickness of which is 0.8nm~8nm; and / or The Al β Ga 1-β The value of β in the N layer ranges from 0.01 to 0.12, and its thickness ranges from 0.3 nm to 2.5 nm; and / or The thickness of the third GaN layer is 5 nm to 16 nm; and / or In z Ga 1-z The value of z in the N layer ranges from 0.1 to 0.13, its thickness ranges from 2 nm to 5 nm, and its emission wavelength ranges from 430 nm to 445 nm; and / or The thickness of the last barrier layer is 5nm-20nm.

4. The light emitting diode epitaxial wafer according to any one of claims 1 to 3, wherein: The Si doping concentration of the first GaN layer is greater than the Si doping concentration of the second GaN layer, and the Si doping concentration of the second GaN layer is greater than the Si doping concentration of the third GaN layer.

5. The light emitting diode epitaxial wafer according to claim 4, wherein: The Si doping concentration of the first GaN layer is 2.5×10 17 cm -3 ~9×10 17 cm -3 and / or The Si doping concentration of the second GaN layer is 1.8×10 17 cm -3 ~7×10 17 cm -3 and / or The Si doping concentration of the third GaN layer is 1.2×10 17 cm -3 ~6×10 17 cm -3 .

6. The light emitting diode epitaxial wafer according to claim 1, wherein: The end well layer is doped with Mg at a concentration of 3×10 18 cm -3 ~8×10 19 cm -3 .

7. The light emitting diode epitaxial wafer according to claim 6, wherein: It also includes a transition well layer and a transition barrier layer sequentially stacked between the third multi-quantum well layer and the final well layer; The transition well layer is In u Ga 1-u N layer, wherein the value of u ranges from 0.1 to 0.13, and the thickness of the transition well layer is from 2 nm to 5 nm; and / or The transition barrier layer is a fifth GaN layer, and its thickness is 5 nm to 20 nm.

8. The light emitting diode epitaxial wafer according to claim 6, wherein: It also includes a hole regulation layer disposed between the last well layer and the last barrier layer; The hole control layer is a periodic structure, and each period includes a Mg-doped InGaN layer and an Al-doped InGaN layer stacked in sequence. γ Ga 1-γ N-layer; Among them, γ≤β.

9. The light emitting diode epitaxial wafer according to claim 8, wherein: The period number of the hole regulation layer is 2 to 10; and / or The ratio of In component in the Mg-doped InGaN layer is 0.01~0.09, and the Mg doping concentration is 2×10 18 cm -3 ~6.5×10 19 cm -3 , the thickness of which is 0.3nm~2.5nm; and / or The Al γ Ga 1-γ The value range of γ in the N layer is 0.01~0.07, and its thickness is 0.5nm~2.5nm.

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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