Micro-led epitaxial structure

Abstract

This invention relates to the field of semiconductor optoelectronic devices, specifically disclosing a Micro-LED epitaxial structure, which sequentially comprises a substrate, a buffer layer, an N-type GaN layer, a stress relief layer, a first superlattice layer, an electron modulation layer, a light-emitting layer, a hole modulation layer, a second superlattice layer, and a P-type GaN layer; the stress relief layer includes In... α Ga 1‑α The N-layer and the first GaN layer; the first superlattice layer includes In. x Ga 1‑x N-layer and second GaN layer; electronic modulation layer includes Al a Ga 1‑a The light-emitting layer includes an N-layer and a third GaN layer, and the light-emitting layer includes an In layer. y Ga 1‑y N quantum well layer and quantum barrier layer, hole modulation layer including Al b Ga 1‑b N layers and In c Ga 1‑c N-layer, the second superlattice layer includes In z Ga 1‑z The N-layer and the fourth GaN layer have the following parameters: y > x > α, y > z, a ≥ b, and the number of periods in the light-emitting layer is ≤ 8. Implementing this invention can improve the luminous efficacy and luminous uniformity of Micro-LEDs at low current densities.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic devices, and more particularly to a Micro-LED epitaxial structure. Background Technology

[0002] In GaN materials, due to the inconsistency between P-type and N-type doping elements, the concentrations of electrons and holes are often inconsistent, and their migration rates are also inconsistent. This leads to electron-hole mismatch in the multi-quantum-well layer (light-emitting layer), reducing luminous efficiency. This phenomenon is particularly pronounced in small-size (≤100μm) and low-current-density (0.1~2A / cm²) materials. 2 This is even more pronounced in Micro-LEDs. Moreover, the wavelength shift is often significant under different current densities, posing a great challenge to high-quality displays.

[0003] One common approach is to reduce the number of cycles in the multiple quantum well layers. While this improves carrier matching efficiency and luminescence efficiency, it also results in significant wavelength shift inconsistencies at different current densities, leading to a decrease in luminescence quality. Another common approach is to use combinations of different In compositions in the quantum well layers, such as combining In... 0.2 Ga 0.8 N-layer converted to In 0.1 Ga 0.9 N+In 0.15 Ga 0.85 N+In 0.1 Ga 0.9 While the N-structure can improve luminous efficiency at low current densities to some extent, its varying In composition often exacerbates polarization, leading to significant changes in luminous efficiency with varying current densities. Furthermore, different In compositions alter carrier transport paths, especially in the presence of a piezoelectric field, causing substantial changes in carrier transport and resulting in inconsistent wavelength shifts at different current densities, reducing luminous uniformity. Moreover, this structure is prone to carrier tunneling at higher current densities, further reducing luminous efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a Micro-LED epitaxial structure that can improve the luminous efficacy and luminous uniformity under low current density.

[0005] To address the aforementioned problems, this invention discloses a Micro-LED epitaxial structure, comprising a substrate, and sequentially stacked layers of a buffer layer, an N-type GaN layer, a stress relief layer, a multiple quantum well layer, and a P-type GaN layer on the substrate; the stress relief layer comprises alternately stacked In... α Ga 1-α N-layer and the first GaN layer;

[0006] The multi-quantum well layer includes a first superlattice layer, an electron modulation layer, a light-emitting layer, a hole modulation layer, and a second superlattice layer, which are sequentially stacked on the stress relief layer.

[0007] The first superlattice layer comprises alternating layers of In x Ga 1-x The N-layer and the second GaN layer; the electronic modulation layer comprises alternating layers of Al a Ga 1-a The light-emitting layer comprises an N-layer and a third GaN layer, the light-emitting layer comprising alternating layers of In. y Ga 1-y The N-quantum well layer and quantum barrier layer, the hole modulation layer comprising alternating layers of Al b Ga 1-b N layers and In c Ga 1-c N layers, the second superlattice layer comprising alternating layers of In z Ga 1-z N-layer and fourth GaN layer;

[0008] Where y > x > α, y > z, a ≥ b, and the number of periods of the light-emitting layer is ≤ 8.

[0009] As an improvement to the above technical solution, the second GaN layer is doped with Si, and the third GaN layer is doped with Si; the doping element in the N-type GaN layer is Si.

[0010] Furthermore, the Si doping concentration in the third GaN layer is less than the Si doping concentration in the second GaN layer; and the Si doping concentration in the second GaN layer is less than the Si doping concentration in the N-type GaN layer.

[0011] As an improvement to the above technical solution, the Si doping concentration in the N-type GaN layer is 5 × 10⁻⁶. 18 cm -3 ~5×10 19 cm -3 ;

[0012] The Si doping concentration in the second GaN layer is 5 × 10⁻⁶. 17 cm -3 ~3×10 18 cm -3 ;

[0013] The Si doping concentration in the third GaN layer is 1×10⁻⁶. 17 cm -3 ~8×10 17 cm -3 .

[0014] As an improvement to the above technical solution, the number of cycles of the electronic modulation layer is 3 to 10;

[0015] Along the growth direction of the Micro-LED epitaxial structure, multiple Al a Ga 1-a The proportion of Al component in the N layer increases progressively.

[0016] As an improvement to the above technical solution, the stress relief layer has 3 to 15 cycles; and / or

[0017] The In α Ga 1-α The thickness of the N layer is 2nm~5nm, and the value of α ranges from 0.05 to 0.1; and / or

[0018] The thickness of the first GaN layer is 5nm~10nm; and / or

[0019] The number of periods in the first superlattice layer is 2 to 5; and / or

[0020] The In x Ga 1-x The thickness of layer N is 2nm~5nm, and the value of x ranges from 0.08 to 0.15; and / or

[0021] The thickness of the second GaN layer is 5nm~15nm; and / or

[0022] The period number of the electronic modulation layer is 3 to 10; and / or

[0023] The Al a Ga 1-a The thickness of layer N is 0.5 nm to 1.5 nm, and the value of α ranges from 0.01 to 0.35; and / or

[0024] The thickness of the third GaN layer is 0.5 nm to 1.5 nm.

[0025] As an improvement to the above technical solution, the light-emitting layer includes a first light-emitting layer and a second light-emitting layer sequentially stacked on the electronic modulation layer;

[0026] The first light-emitting layer comprises alternating layers of In y Ga 1-y The first light-emitting layer consists of an N quantum well layer and a Si-doped GaN layer; the number of periods in the first light-emitting layer is 2 to 4.

[0027] The second light-emitting layer comprises alternating layers of In y Ga 1-y N quantum well layer and Al d Ga 1-dThe Nth layer; the number of periods in the second light-emitting layer is 2 to 4.

[0028] As an improvement to the above technical solution, the In y Ga 1-y The thickness of the N quantum well layer is 2nm~5nm, and the value of y ranges from 0.15 to 0.35; and / or

[0029] The thickness of the Si-doped GaN layer is 5 nm to 10 nm, and its Si doping concentration is 1 × 10⁻⁶. 17 cm -3 ~5×10 17 cm -3 ; and / or

[0030] The Al d Ga 1-d The thickness of the N layer is 5nm~10nm, and the value of d ranges from 0.1 to 0.3.

[0031] As an improvement to the above technical solution, the number of cycles of the hole modulation layer is 3 to 8;

[0032] Along the growth direction of the Micro-LED epitaxial structure, multiple Al b Ga 1-b The proportion of Al component in the N layer decreases.

[0033] As an improvement to the above technical solution, the In c Ga 1-c The N-layer is doped with Mg at a concentration of 3 × 10⁻⁶. 18 cm -3 ~5×10 19 cm -3 ;

[0034] The fourth GaN layer is doped with Mg at a concentration of 1×10⁻⁶. 19 cm -3 ~8×10 19 cm -3 .

[0035] As an improvement to the above technical solution, the number of cycles in the hole modulation layer is 3 to 5; and / or

[0036] The Al b Ga 1-b The thickness of the N layer is 0.5 nm to 1.5 nm, and the value of b ranges from 0.05 to 0.3; and / or

[0037] The In c Ga 1-c The thickness of the N layer is 0.5 nm to 1.5 nm, and the value of c ranges from 0.05 to 0.15; and / or

[0038] The second superlattice layer has a period number of 2 to 5; and / or

[0039] The In z Ga 1-z The thickness of layer N is 1 nm to 3 nm, and the value of z ranges from 0.05 to 0.1; and / or

[0040] The thickness of the fourth GaN layer is 3nm~10nm.

[0041] Implementing this invention has the following beneficial effects:

[0042] In one embodiment of the present invention, the Micro-LED epitaxial structure includes a multi-quantum-well layer comprising a first superlattice layer, an electron modulation layer, a light-emitting layer, a hole modulation layer, and a second superlattice layer sequentially stacked on a stress-relieving layer; wherein the first superlattice layer comprises alternating layers of In x Ga 1-x N-layer and second GaN layer; electronic modulation layer comprising alternating layers of Al a Ga 1-a The light-emitting layer consists of an N-layer and a third GaN layer, and the light-emitting layer comprises alternating layers of In. y Ga 1-y The N-quantum well layer and quantum barrier layer, and the hole modulation layer consist of alternating layers of Al b Ga 1-b N layers and In c Ga 1-c The N-layer, the second superlattice layer comprises alternating layers of In. z Ga 1-z The structure consists of an N-layer and a fourth GaN layer, where y > x > α, y > z, a ≥ b, and the number of periods in the emitting layer is ≤ 8. The stress-relieving layer and the first superlattice layer work together to buffer the piezoelectric field within the emitting layer, increasing the recombination probability of electrons and holes and improving luminous efficiency. The electron modulation layer primarily reduces electron mobility, while the hole modulation layer effectively increases the migration rate of hole carriers. Both layers effectively improve the electron-hole matching degree in the emitting layer, enhancing luminous efficiency at low current densities and reducing wavelength shift. The second superlattice layer primarily blocks the further extension of defects in the emitting layer, thereby effectively improving the crystal quality of the P-type GaN layer and increasing the hole concentration. Therefore, the structure described in this technical solution not only weakens the piezoelectric field intensity in the emitting layer but also improves the matching degree of holes and electrons, effectively enhancing the luminous efficiency of the Micro-LED epitaxial structure at low current densities, and resulting in high luminous efficiency and minimal wavelength shift at different current densities. Attached Figure Description

[0043] Figure 1This is a schematic diagram of the Micro-LED epitaxial structure in one embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the structure of a 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 Figure 1 and Figure 2 The present invention discloses a Micro-LED epitaxial structure, which includes a substrate 100, a buffer layer 200, an N-type GaN layer 300, a stress relief layer 400, a multi-quantum well layer 500 and a P-type GaN layer 600 sequentially stacked on the substrate 100.

[0047] Among them, the stress relief layer 400 includes alternating layers of In α Ga 1-α N-layer 410 and first GaN layer 420;

[0048] The multi-quantum well layer 500 includes a first superlattice layer 510, an electron modulation layer 520, a light-emitting layer 530, a hole modulation layer 540, and a second superlattice layer 550, which are sequentially stacked on the stress relief layer 400.

[0049] The first superlattice layer 510 comprises alternating layers of In x Ga 1-x N-layer 511 and second GaN layer 512; electronic modulation layer 520 includes alternating layers of Al a Ga 1-a The N-layer 521 and the third GaN layer 522, and the light-emitting layer 530 include alternating layers of In y Ga 1-y The N quantum well layer 531 and quantum barrier layer 532, and the hole modulation layer 540 include alternating layers of Al b Ga 1-b N layer 541 and In c Ga 1-c N layer 542, the second superlattice layer 550 includes alternating layers of In z Ga 1-zThe light-emitting layer 530 consists of an N-layer 551 and a fourth GaN layer 552, where y > x > α, y > z, a ≥ b, and the number of periods in the light-emitting layer 530 is ≤ 8. The piezoelectric field within the light-emitting layer 530 is significantly weakened by the combined buffering effect of the stress-relieving layer 400 and the first superlattice layer 510, increasing the recombination probability of electrons and holes and improving luminous efficiency. The electron modulation layer 520 primarily reduces electron mobility, while the hole modulation layer 540 effectively increases the migration rate of hole carriers. Together, they enhance the electron-hole matching degree in the light-emitting layer 530, improving luminous efficiency at low current densities and reducing wavelength shift. The second superlattice layer 550 primarily blocks the further extension of defects in the light-emitting layer 530, thereby effectively improving the crystal quality of the p-type GaN layer 600 and increasing the hole concentration. Therefore, the structure described above in this technical solution can not only weaken the piezoelectric field intensity in the light-emitting layer 530, but also improve the matching degree of holes and electrons, thereby effectively improving the luminous efficiency of the Micro-LED epitaxial structure under low current density, and making the luminous efficiency higher and the wavelength shift smaller at different current densities.

[0050] The stress relief layer 400 serves as a buffer transition, reducing stress concentration, improving the crystal quality of the light-emitting layer 530, weakening the piezoelectric field, and thus improving luminous efficiency at low current densities. Specifically, the stress relief layer 400 has 3 to 15 periods, exemplarily 4, 6, 8, 10, 12, or 14, but is not limited to these.

[0051] Specifically, in α Ga 1-α The thickness of the N-layer 410 is 2nm to 5nm, exemplarily 2.5nm, 3nm, 3.5nm, 4nm, or 4.5nm, but not limited thereto. Preferably, it is 2nm to 4nm. The value of α ranges from 0.05 to 0.1, exemplarily 0.06, 0.07, 0.08, or 0.09, but not limited thereto. Preferably, it is 0.05 to 0.08.

[0052] Specifically, the thickness of the first GaN layer 420 is 5nm to 10nm, exemplarily 5.5nm, 6nm, 6.5nm, 7nm, 7.5nm, 8nm or 9nm, but not limited thereto. Preferably, it is 5nm to 8nm.

[0053] The first superlattice layer 510 further alleviates stress concentration. Together with the stress relief layer 400, it not only improves the luminous efficiency at low current densities but also optimizes luminous uniformity. Specifically, the number of periods in the first superlattice layer 510 is 2 to 5, exemplarily 3, 4, or 5, but not limited to these.

[0054] Specifically, in xGa 1-x The thickness of the N-layer 511 is 2nm to 5nm, exemplarily 2.5nm, 3nm, 3.5nm, 4nm, or 4.5nm, but not limited thereto. Preferably, it is 2nm to 4nm. The value of x ranges from 0.08 to 0.15, exemplarily 0.09, 0.1, 0.12, or 0.14, but not limited thereto.

[0055] Specifically, the thickness of the second GaN layer 512 is 5nm to 15nm, exemplarily 5.5nm, 7nm, 8.5nm, 10nm, 11.5nm, 13nm or 14.5nm, but not limited thereto.

[0056] The electron modulation layer 520 primarily serves to reduce electron mobility and can disperse electrons into the light-emitting layer 530, thereby improving the uniformity of light emission. Specifically, the number of cycles in the electron modulation layer 520 is 3 to 10, exemplarily 4, 5, 7, or 9, but not limited to these.

[0057] Specifically, Al a Ga 1-a The thickness of the N-layer 521 is 0.5nm to 1.5nm, exemplarily 0.7nm, 0.9nm, 1.1nm, or 1.3nm, but not limited thereto. Preferably, it is 0.8nm to 1.2nm. The value of 'a' ranges from 0.01 to 0.35; exemplarily 0.05, 0.1, 0.15, 0.2, 0.25, or 0.3, but not limited thereto.

[0058] Specifically, the thickness of the third GaN layer 522 is 0.5nm to 1.5nm, exemplarily 0.8nm, 1.0nm, 1.2nm or 1.4nm, but not limited thereto. Preferably, it is 0.7nm to 1.2nm.

[0059] Specifically, the number of cycles in the light-emitting layer 530 is ≤8. The relatively small number of cycles in the light-emitting layer 530 of this technical solution can improve the matching degree between electrons and holes, thereby improving the uniformity and efficiency of light emission. Preferably, in some embodiments, the number of cycles in the light-emitting layer 530 is 3 to 8, exemplarily 4, 5, 6, or 7, but not limited thereto.

[0060] Specifically, in y Ga 1-y The thickness of the N-quantum well layer 531 is 2nm to 5nm, exemplarily 2.5nm, 3nm, 3.5nm, 4nm, or 4.5nm, but not limited thereto. Preferably, it is 2nm to 4nm. The value of y ranges from 0.15 to 0.35, exemplarily 0.18, 0.2, 0.24, 0.28, 0.32, or 0.34, but not limited thereto.

[0061] Specifically, the quantum barrier layer 532 can be a GaN layer, an AlGaN layer, or a Si-doped GaN layer, but is not limited to these. The thickness of the quantum barrier layer 532 is 5nm to 10nm. The small thickness of the quantum barrier layer 532 in this technical solution can reduce vertical resistivity, reduce sidewall recombination, and improve luminous efficiency. For example, the thickness of the quantum barrier layer 532 is 5.5nm, 6nm, 6.5nm, 7nm, 7.5nm, 8nm, 8.5nm, or 9nm, but is not limited to these.

[0062] The hole modulation layer 540 can improve hole mobility and optimize hole distribution, thereby effectively improving the matching degree of electrons and holes in the light-emitting layer 530, and improving luminous efficiency and luminous uniformity. Specifically, the number of cycles in the hole modulation layer 540 is 3 to 8, exemplarily 4, 5, 6, or 7, but not limited thereto; preferably 3 to 5.

[0063] Specifically, Al b Ga 1-b The thickness of the N-layer 541 is 0.5nm to 1.5nm, exemplarily 0.8nm, 1.1nm, or 1.4nm, but not limited thereto. Preferably, it is 0.8nm to 1.2nm. The value of b ranges from 0.05 to 0.3, exemplarily 0.1, 0.15, 0.2, or 0.25, but not limited thereto.

[0064] Specifically, in c Ga 1-c The thickness of the N-layer 542 is 0.5nm to 1.5nm, exemplarily 0.7nm, 0.9nm, 1.1nm, or 1.3nm, but not limited thereto. Preferably, it is 0.8nm to 1.2nm. The value of c ranges from 0.05 to 0.15, exemplarily 0.08, 0.1, 0.12, or 0.14, but not limited thereto. Preferably, it is 0.08 to 0.15.

[0065] The second superlattice layer 550 can block the extension of defects in the light-emitting layer 530, thereby effectively increasing the hole concentration in the p-type GaN layer 600. Furthermore, the second superlattice layer 550 can enhance hole dispersion, allowing holes to be injected more uniformly into the light-emitting layer 530. Specifically, the number of periods in the second superlattice layer 550 is 2 to 5, exemplarily 3, 4, or 5, but not limited to these.

[0066] Specifically, in z Ga 1-zThe thickness of the N-layer 551 is 1nm to 3nm, exemplarily 1.2nm, 1.4nm, 1.8nm, 2.2nm, 2.6nm, or 2.8nm, but not limited thereto. Preferably, it is 1nm to 2nm. The value of z ranges from 0.05 to 0.1, exemplarily 0.06, 0.07, 0.08, or 0.09, but not limited thereto. Preferably, it is 0.05 to 0.08.

[0067] Specifically, the thickness of the fourth GaN layer 552 is 3nm to 10nm, exemplarily 4nm, 5nm, 6nm, 7nm, 8nm or 9nm, but not limited thereto. Preferably, it is 5nm to 10nm.

[0068] The substrate 100 is a sapphire substrate or a silicon substrate, but is not limited to these.

[0069] The buffer layer 200 is an AlN layer, a low-temperature GaN layer, or an AlGaN layer, but is not limited to these. The thickness of the buffer layer 200 is 30nm~80nm.

[0070] The N-type GaN layer 300 is doped with Si, but is not limited to Si. The Si doping concentration in the N-type GaN layer 300 is 5 × 10⁻⁶. 18 cm -3 ~5×10 19 cm -3 Its thickness is 1μm~5μm.

[0071] The doping element in the p-type GaN layer 600 is Mg, but it is not limited to Mg. The doping concentration of Mg in the p-type GaN layer 600 is 1×10⁻⁶. 19 cm -3 ~5×10 20 cm -3 Its thickness is 80nm~200nm.

[0072] Preferably, in some embodiments, the second GaN layer 512 is doped with Si, and the third GaN layer 522 is doped with Si; and the Si doping concentration in the third GaN layer 522 is less than the Si doping concentration in the second GaN layer 512 is less than the Si doping concentration in the N-type GaN layer 300. Based on this structure, the electron carrier migration rate can be further reduced, the electron-hole matching degree in the light-emitting layer 530 can be improved, and the luminous uniformity and luminous efficiency can be improved. More specifically, the Si doping concentration in the second GaN layer 512 is 5 × 10⁻⁶. 17 cm -3 ~3×10 18 cm -3 The Si doping concentration in the third GaN layer 522 is 1×10⁻⁶. 17 cm -3 ~8×1017 cm -3 .

[0073] Preferably, in some embodiments, multiple Al atoms are arranged along the growth direction of the Micro-LED epitaxial structure. a Ga 1-a The proportion of Al in the N-layer 521 increases progressively. Based on this structure, firstly, the increasing Al content raises the potential barrier height, further modulating the electron mobility. Secondly, the gradually increasing Al content further reduces the electric field intensity generated by piezoelectric polarization in the light-emitting layer 530. Combined, these two factors further improve luminescence uniformity and luminescence efficiency. More specifically, in some embodiments, multiple Al... a Ga 1-a The proportion of Al component in the N-layer 521 increases from 0.01~0.05 to 0.2~0.35.

[0074] Preferably, in some embodiments, the light-emitting layer 530 includes a first light-emitting layer and a second light-emitting layer sequentially stacked on the electronic modulation layer 520; the first light-emitting layer includes alternately stacked In... y Ga 1-y The first light-emitting layer consists of an N quantum well layer and a Si-doped GaN layer; the first light-emitting layer has 2 to 4 periods; the second light-emitting layer comprises alternating layers of In. y Ga 1-y N quantum well layer and Al d Ga 1-d The second luminescent layer has N layers; the number of periods in the second luminescent layer is 2 to 4. Based on this structure, the polarization electric field intensity within the luminescent layer 530 can be further weakened, thereby improving the luminous density and luminous uniformity at low current densities.

[0075] More specifically, In y Ga 1-y The thickness of the N-quantum well layer 531 is 2nm~5nm, and the value of y ranges from 0.15 to 0.35; the thickness of the Si-doped GaN layer is 5nm~10nm, and its Si doping concentration is 1×10⁻⁶. 17 cm -3 ~5×10 17 cm -3 Al d Ga 1-d The thickness of the N layer is 5nm~10nm, and the value of d ranges from 0.1 to 0.3.

[0076] Preferably, in some embodiments, multiple Al atoms are arranged along the growth direction of the Micro-LED epitaxial structure. b Ga 1-bThe proportion of Al component in the N-layer 541 decreases progressively. Based on this structure, the migration rate of holes can be further improved, the matching degree of electrons and holes in the light-emitting layer 530 can be optimized, and the luminous efficiency and luminous uniformity under low current density can be improved. More specifically, in some embodiments, Al... b Ga 1-b The proportion of Al component in layer 541 decreases from 0.2~0.3 to 0.05~0.1%.

[0077] Preferably, in some embodiments of the present invention, the Micro-LED epitaxial structure may further include an undoped GaN layer disposed between the buffer layer 200 and the N-type GaN layer 300, with a thickness of 1μm to 3μm.

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

[0079] Example 1

[0080] This embodiment provides a Micro-LED epitaxial structure, which includes a substrate, and a buffer layer, an N-type GaN layer, a stress relief layer, a multiple quantum well layer and a P-type GaN layer 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 Si doping concentration in the N-type GaN layer is 8.5 × 10⁻⁶. 18 cm -3 Its thickness is 3 μm. The stress relief layer consists of alternating layers of In. α Ga 1-α The N-layer (α=0.06) and the first GaN layer have a period number of 10. α Ga 1-α The thickness of the N layer is 3nm, and the thickness of the first GaN layer is 6nm.

[0082] The multi-quantum well layer includes a first superlattice layer, an electron modulation layer, a light-emitting layer, a hole modulation layer, and a second superlattice layer, which are sequentially stacked on the stress relief layer.

[0083] The first superlattice layer consists of alternating layers of In x Ga 1-x The N-layer (x=0.11) and the second GaN layer have a period number of 4; In x Ga 1-x The thickness of the N layer is 3nm, and the thickness of the second GaN layer is 12nm.

[0084] The electronic modulation layer consists of alternating layers of Al a Ga 1-a The N-layer (a=0.25) and the third GaN layer have a period number of 5. In different periods, Ala Ga 1-a The proportion of Al component in the N layer remains constant. a Ga 1-a The thickness of the N layer is 1.1 nm, and the thickness of the third GaN layer is 1.2 nm.

[0085] The light-emitting layer consists of alternating layers of In y Ga 1-y The N quantum well layer (y=0.22) and the quantum barrier layer (Si-doped GaN layer) have a period number of 6. y Ga 1-y The thickness of the N-quantum well layer is 3 nm, the thickness of the quantum barrier layer is 8.8 nm, and its Si doping concentration is 4.4 × 10⁻⁶. 17 cm -3 .

[0086] Hole modulation layer comprises alternating layers of Al b Ga 1-b N layers (b=0.15) and In c Ga 1-c N layers (c=0.11), with a period number of 4, Al b Ga 1-b The thickness of the N layer is 1.2 nm, In c Ga 1-c The thickness of the N layer is 1 nm.

[0087] The second superlattice layer consists of alternating layers of In z Ga 1-z N-layer (z=0.08) and the fourth GaN layer, In z Ga 1-z The thickness of the N layer is 2nm, and the thickness of the fourth GaN layer is 10nm.

[0088] The Mg doping concentration in the P-type GaN layer is 8 × 10⁻⁶. 19 cm -3 Its thickness is 200nm.

[0089] Example 2

[0090] This embodiment provides a Micro-LED epitaxial structure, which differs from Embodiment 1 in that:

[0091] The second GaN layer is doped with Si at a concentration of 8.5 × 10⁻⁶. 17 cm -3 The third GaN layer is doped with Si at a concentration of 3.3 × 10⁻⁶. 17 cm -3 .

[0092] Everything else is the same as in Example 1.

[0093] Example 3

[0094] This embodiment provides a Micro-LED epitaxial structure, which differs from Embodiment 2 in that:

[0095] Along the growth direction of the Micro-LED epitaxial structure, multiple Al a Ga 1-a The proportion of Al component in the N layer increases progressively. Specifically, in each period, Al... a Ga 1-a The proportions of Al components in the N layer were 0.05, 0.1, 0.15, 0.2, and 0.25, respectively.

[0096] Everything else is the same as in Example 2.

[0097] Example 4

[0098] This embodiment provides a Micro-LED epitaxial structure, which differs from Embodiment 3 in that: the light-emitting layer includes a first light-emitting layer and a second light-emitting layer sequentially stacked on the electronic modulation layer;

[0099] The first light-emitting layer comprises alternating layers of In y Ga 1-y N quantum well layer (y=0.22) and Si-doped GaN layer; its period number is 3; In y Ga 1-y The thickness of the N-quantum well layer is 3 nm, and the thickness of the Si-doped GaN layer is 8.8 nm, with a Si doping concentration of 4.4 × 10⁻⁶. 17 cm -3 .

[0100] The second light-emitting layer comprises alternating layers of In y Ga 1-y N quantum well layer (y=0.22) and Al d Ga 1-d N layers (d=0.15); its period number is 3. In y Ga 1-y The thickness of the N quantum well layer is 3 nm, and Al d Ga 1-d The thickness of the N layer is 8.5 nm.

[0101] Everything else is the same as in Example 3.

[0102] Example 5

[0103] This embodiment provides a Micro-LED epitaxial structure, which differs from Embodiment 4 in that:

[0104] Along the growth direction of the Micro-LED epitaxial structure, multiple Al b Ga 1-b The proportion of Al component in the N layer decreases progressively. Specifically, the Al content in each period... b Ga 1-b The proportions of Al components in the N layer were 0.25, 0.2, 0.15, and 0.1%, respectively.

[0105] Everything else is the same as in Example 4.

[0106] Example 6

[0107] This embodiment provides a Micro-LED epitaxial structure, which differs from Embodiment 5 in that:

[0108] In c Ga 1-c The N-layer is doped with Mg at a concentration of 4.5 × 10⁻⁶. 18 cm -3 The fourth GaN layer is doped with Mg at a concentration of 3.5 × 10⁻⁶. 19 cm -3 .

[0109] Everything else is the same as in Example 5.

[0110] Comparative Example 1

[0111] This comparative example provides a Micro-LED epitaxial structure, which differs from Example 1 in that:

[0112] Multiple quantum well layers consist of alternating layers of In 0.22 Ga 0.78 N-layers and GaN-layers, In 0.22 Ga 0.78 The thickness of the N layer is 3nm, and the thickness of the GaN layer is 10nm.

[0113] Everything else is the same as in Example 1.

[0114] Comparative Example 2

[0115] This comparative example provides a Micro-LED epitaxial structure, which differs from Example 1 in that:

[0116] Excluding the first and second superlattice layers, the rest are the same as in Example 1.

[0117] Comparative Example 3

[0118] This comparative example provides a Micro-LED epitaxial structure, which differs from Example 1 in that:

[0119] Excluding the electron modulation layer and hole modulation layer, everything else is the same as in Example 1.

[0120] The epitaxial structures obtained in Examples 1-6 and Comparative Examples 1-3 were used to fabricate Micro-LEDs with a size of 50 μm × 50 μm and a horizontal structure, and were tested at 0.1 A / cm². 2 1A / cm 2 The luminous power and wavelength uniformity (PL-WD std) were tested at a current density, and the luminous power enhancement rate was calculated based on the data of Comparative Example 1. The specific results are shown in the table below:

[0121]

[0122] 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 Micro-LED epitaxial structure, characterized in that, The substrate includes a buffer layer, an N-type GaN layer, a stress relief layer, a multiple quantum well layer, and a P-type GaN layer sequentially stacked on the substrate; the stress relief layer comprises alternating layers of In. α Ga 1-α N-layer and the first GaN layer; The multi-quantum well layer includes a first superlattice layer, an electron modulation layer, a light-emitting layer, a hole modulation layer, and a second superlattice layer, which are sequentially stacked on the stress relief layer. The first superlattice layer comprises alternating layers of In x Ga 1-x The N-layer and the second GaN layer; the electronic modulation layer comprises alternating layers of Al a Ga 1-a The light-emitting layer comprises an N-layer and a third GaN layer, the light-emitting layer comprising alternating layers of In. y Ga 1-y The N-quantum well layer and quantum barrier layer, the hole modulation layer comprising alternating layers of Al b Ga 1-b N layers and In c Ga 1-c N layers, the second superlattice layer comprising alternating layers of In z Ga 1-z N-layer and fourth GaN layer; Wherein, α ranges from 0.05 to 0.1, x ranges from 0.08 to 0.15, a ranges from 0.01 to 0.35, y ranges from 0.15 to 0.35, b ranges from 0.05 to 0.3, c ranges from 0.05 to 0.15, z ranges from 0.05 to 0.1, y > x > α, y > z, a ≥ b, and the number of periods of the light-emitting layer is ≤ 8; The number of cycles in the electronic modulation layer is 3 to 10; Along the growth direction of the Micro-LED epitaxial structure, multiple Al a Ga 1-a The proportion of Al component in the N layer increases gradually. The number of cycles in the hole modulation layer is 3 to 8; Along the growth direction of the Micro-LED epitaxial structure, multiple Al b Ga 1-b The proportion of Al component in the N layer decreases.

2. The Micro-LED epitaxial structure as described in claim 1, characterized in that, The second GaN layer is doped with Si, and the third GaN layer is also doped with Si; the doping element in the N-type GaN layer is Si. Furthermore, the Si doping concentration in the third GaN layer is less than the Si doping concentration in the second GaN layer; and the Si doping concentration in the second GaN layer is less than the Si doping concentration in the N-type GaN layer.

3. The Micro-LED epitaxial structure as described in claim 2, characterized in that, The Si doping concentration in the N-type GaN layer is 5 × 10⁻⁶. 18 cm -3 ~5×10 19 cm -3 ; The Si doping concentration in the second GaN layer is 5 × 10⁻⁶. 17 cm -3 ~3×10 18 cm -3 ; The Si doping concentration in the third GaN layer is 1×10⁻⁶. 17 cm -3 ~8×10 17 cm -3 .

4. The Micro-LED epitaxial structure as described in claim 1, characterized in that, The stress relief layer has 3 to 15 cycles; and / or The In α Ga 1-α The thickness of the N layer is 2nm~5nm; and / or The thickness of the first GaN layer is 5nm~10nm; and / or The number of periods in the first superlattice layer is 2 to 5; and / or The In x Ga 1-x The thickness of the N layer is 2nm~5nm; and / or The thickness of the second GaN layer is 5nm~15nm; and / or The period number of the electronic modulation layer is 3 to 10; and / or The Al a Ga 1-a The thickness of the N layer is 0.5 nm to 1.5 nm; and / or The thickness of the third GaN layer is 0.5 nm to 1.5 nm.

5. The Micro-LED epitaxial structure as described in claim 1, characterized in that, The light-emitting layer includes a first light-emitting layer and a second light-emitting layer sequentially stacked on the electronic modulation layer; The first light-emitting layer comprises alternating layers of In y Ga 1-y The first light-emitting layer consists of an N quantum well layer and a Si-doped GaN layer; the number of periods in the first light-emitting layer is 2 to 4. The second light-emitting layer comprises alternating layers of In y Ga 1-y N quantum well layer and Al d Ga 1-d N layers; the second light-emitting layer has 2 to 4 periods, and the value of d ranges from 0.1 to 0.

3.

6. The Micro-LED epitaxial structure as described in claim 5, characterized in that, The In y Ga 1-y The thickness of the N-quantum well layer is 2nm~5nm; and / or The thickness of the Si-doped GaN layer is 5 nm to 10 nm, and its Si doping concentration is 1 × 10⁻⁶. 17 cm -3 ~5×10 17 cm -3 ; and / or The Al d Ga 1-d The thickness of the N layer is 5nm~10nm.

7. The Micro-LED epitaxial structure as described in claim 1, characterized in that, The In c Ga 1-c The N-layer is doped with Mg at a concentration of 3 × 10⁻⁶. 18 cm -3 ~5×10 19 cm -3 ; The fourth GaN layer is doped with Mg at a concentration of 1×10⁻⁶. 19 cm -3 ~8×10 19 cm -3 .

8. The Micro-LED epitaxial structure as described in claim 1, characterized in that, The number of periods in the hole modulation layer is 3 to 5; and / or The Al b Ga 1-b The thickness of the N layer is 0.5 nm to 1.5 nm; and / or The In c Ga 1-c The thickness of the N layer is 0.5 nm to 1.5 nm; and / or The second superlattice layer has a period number of 2 to 5; and / or The In z Ga 1-z The thickness of the N layer is 1nm~3nm; and / or The thickness of the fourth GaN layer is 3nm~10nm.

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