GaN-based mini LED epitaxial structure and preparation method

Abstract

The application relates to the fields of semiconductor photoelectric devices and semiconductor display manufacturing, and particularly relates to a GaN-based Mini LED epitaxial structure and a preparation method thereof. In the preparation method, when an active region multi-quantum well layer is grown, the temperature of a reaction cavity is set to 800-950 DEG C, a well-barrier temperature difference is 100-150 DEG C, and a potential well layer and a potential barrier layer are alternately grown; when the potential well layer is grown, the pressure of the reaction cavity is 100-190 Tor, the rotating speed is 300-500 r / min, and the carrier gas is H2; when the potential barrier layer is grown, the pressure of the reaction cavity is 200-400 Tor, and the rotating speed is 600-700 r / min. The active region multi-quantum well layer is grown by adopting a slow-speed long-well fast-speed long-barrier method, the Stark effect can be effectively relieved, the stress is reduced, and the luminous efficiency is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the fields of semiconductor photoelectric devices and semiconductor display manufacturing, and in particular to a GaN-based Mini LED epitaxial structure and a preparation method thereof. BACKGROUND

[0002] A light-emitting diode (LED) releases energy by combining electrons and holes to convert electrical energy into light energy to realize light emission of the light-emitting diode. Industrial production of the light-emitting diode is mainly blue-green light-emitting diodes, which are widely used in displays and lighting.

[0003] With the increasing requirements of display brightness, contrast and resolution of the light-emitting diode, a micro light-emitting diode (Micro LED) is developed in the field. The micro light-emitting diode designs the light-emitting diode structure to be thin, small and arrayed, and reduces the pixel distance from millimeter level to micrometer level, which shows great advantages in brightness, contrast and reliability.

[0004] A Chinese invention patent with the publication number CN113270525A discloses a preparation method of a green light epitaxial structure. The quantum well active region in the structure is grown by using GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN segmented growth can improve well-barrier mismatch, relieve the Stark effect and improve light-emitting efficiency. However, for the Mini (sub-millimeter) LED with high consistency requirements, the consistency (such as wavelength consistency, light-emitting intensity consistency, color consistency, etc.) of various parameters of the LED is poor when the active region is grown by using the above method, which seriously affects the display effect of the Mini LED. SUMMARY

[0005] In order to overcome the defects of the prior art, the technical problem to be solved by the application is to improve a GaN-based Mini LED epitaxial structure and a preparation method thereof.

[0006] In order to solve the above technical problems, the technical scheme adopted by the application is as follows: a preparation method of a GaN-based Mini LED epitaxial structure, when growing a multi-quantum well layer of an active region, the temperature of a reaction cavity is set to 800-950 DEG C, the well-barrier temperature difference is 100-150 DEG C, and a potential well layer and a potential barrier layer are alternately grown.

[0007] When the potential well layer is grown, the pressure of the reaction cavity is 100-190 Tor, the rotation speed is 300-500 r / min, and the carrier gas is H2; when the potential barrier layer is grown, the pressure of the reaction cavity is 200-400 Tor, and the rotation speed is 600-700 r / min.

[0008] Another technical solution of the application is the GaN-based Mini LED epitaxial structure prepared by the preparation method.

[0009] The GaN-based Mini LED epitaxial structure has the advantages that the preparation method of the GaN-based Mini LED epitaxial structure uses low pressure and low rotation speed when growing the potential well layer, the growth rate is slow, and the In source can be uniformly distributed on the epitaxial wafer; high pressure and high rotation speed are used when growing the potential barrier layer, the growth rate is fast, and the In precipitation can be prevented, thereby improving the light-emitting efficiency. The active region multi-quantum well layer is grown by the method of slow long well and fast long barrier, which can effectively relieve the Stark effect, reduce stress, and improve the light-emitting efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 Fig. 1 is a structural schematic diagram of a GaN-based Mini LED epitaxial structure according to an embodiment of the application;

[0011] Label explanation: 1, AlN substrate; 2, AlGaN / GaN buffer layer; 3, high-temperature undoped UGaN layer; 4, first n-GaN layer; 5, n-AlGaN layer; 6, multi-period Si-doped NGaN layer; 7, superlattice InGaN / GaN stress release layer; 8, active region multi-quantum well layer; 9, u-AlGaN layer; 10, low-temperature Mg-doped first p-GaN layer; 11, p-AlGaN layer; 12, high-temperature Mg-doped second p-GaN layer. DETAILED DESCRIPTION

[0012] To make the technical content of the application, the purposes and effects achieved more clear, the following will be described in detail in combination with the embodiments and the accompanying drawings.

[0013] The most key idea of the application is that the active region multi-quantum well layer is grown by the method of slow long well and fast long barrier, which can effectively relieve the Stark effect, reduce stress, and improve the light-emitting efficiency.

[0014] Please refer to Figure 1 Fig. 1, a preparation method of a GaN-based Mini LED epitaxial structure, when growing the active region multi-quantum well layer, the temperature of the reaction cavity is set to 800-950℃, the well-barrier temperature difference (the temperature of the potential barrier layer is higher) is 100-150℃, and the potential well layer and the potential barrier layer are alternately grown.

[0015] When growing the potential well layer, the pressure of the reaction cavity is 100-190 Tor, the rotation speed is 300-500 r / min, and the carrier gas is H2; when growing the potential barrier layer, the pressure of the reaction cavity is 200-400 Tor, and the rotation speed is 600-700 r / min.

[0016] From the above description, the beneficial effects of the present application are that the active region multi-quantum well layer adopts the method of slow long well and fast long barrier to alternately grow a plurality of periods of potential well layer and potential barrier layer. When growing the potential well layer, low pressure and low rotation speed are used, the growth rate is slow, and the In source can be uniformly distributed on the epitaxial wafer; when growing the potential barrier layer, high pressure and high rotation speed are used, the growth rate is fast, which can prevent the precipitation of In and improve the luminous efficiency. The active region multi-quantum well layer is repeatedly grown in this way to release stress multiple times, which reduces the accumulation of stress and has better stress release effect, so as to greatly improve the warping of the epitaxial wafer, effectively alleviate the Stark effect, and the In source can be uniformly distributed on the epitaxial wafer during the growth of the active layer, and the consistency of various parameters of the LED is better.

[0017] Further, the potential well layer is GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN (0.05 < x1 < 0.15, 0.15 < x2 < 0.3), with a thickness of 5-10 nm; the potential barrier layer is GaN / Al y1 Ga 1－y1 N (0.1 < y1 < 0.3), with a thickness of 5-15 nm.

[0018] From the above description, the content of x1 and the content of x2 are adjusted by temperature, pressure and rotation speed, and the design of In content by quantum well segmented growth structure and temperature adjustment can reduce the well-barrier mismatch, thereby alleviating the Stark effect, reducing dislocations and improving the luminous efficiency.

[0019] Further, the thickness of In x2 Ga 1－x2 N in the potential well layer is 1-3.5 nm.

[0020] From the above description, too thin or too thick In x2 Ga 1－x2 N in the potential well layer outside the above range will reduce the luminous efficiency.

[0021] Further, the active region multi-quantum well layer comprises a stack of 1-10 groups of potential well layers and potential barrier layers.

[0022] From the above description, since the InGaN quantum well layer is a high In component material, In-rich nanoclusters and V-shaped pits are grown on the surface, so that the surface of the InGaN quantum well layer is uneven and a large number of defects or dislocations are formed, thereby causing the problem of poor crystal quality at the interface between the quantum well and the quantum barrier; and the strain caused by growing the InGaN quantum well layer on the GaN polar surface produces a strong built-in polarization field, resulting in electron-hole spatial separation in the light-emitting layer, greatly reducing the radiation recombination rate and affecting the internal quantum efficiency (IQE) of the light-emitting diode. If the number of groups is too large or too small, the light efficiency will be poor. The thickness of the active region multi-quantum well layer is controlled to be 180-300 nm by controlling the number of groups.

[0023] Further, the barrier layer is Si-doped GaN.

[0024] From the above description, the barrier layer is Si-doped GaN, which can reduce dislocations.

[0025] Further, on the AlN substrate, an AlGaN / GaN buffer layer, a high-temperature undoped UGaN layer, a first n-GaN layer, an n-AlGaN layer, a multi-period Si-doped NGaN layer, a superlattice InGaN / GaN stress release layer, an active region multi-quantum well layer, a u-AlGaN layer, a low-temperature Mg-doped first p-GaN layer, a p-AlGaN layer, and a high-temperature Mg-doped second p-GaN layer are sequentially grown.

[0026] Further, the AlGaN / GaN buffer layer is grown in a reaction chamber, the temperature of the reaction chamber is 700-900℃, the pressure is 100-300Torr, the rotation speed is 800-1200r / min, the carrier gas is H2, and the V / III molar ratio is 60-100.

[0027] Further, the thickness of the AlGaN / GaN buffer layer is 0.005-0.1um.

[0028] From the above description, the AlGaN / GaN buffer layer is beneficial to carrier transport.

[0029] Further, the high-temperature undoped UGaN layer is grown in a reaction chamber, the temperature of the reaction chamber is 1050-1100℃, the pressure is 150-300Torr, the rotation speed is 800-1200r / min, the carrier gas is H2, and the V / III molar ratio is 100-300.

[0030] Further, the thickness of the high-temperature undoped UGaN layer is 1-3um.

[0031] Furthermore, the growth of the first n-GaN layer is carried out in a reaction chamber at a temperature of 1050–1100 °C, a pressure of 150–300 Torr, a rotation speed of 800–1200 r / min, a carrier gas of H2, a V / III molar ratio of 100–300, and a doping concentration of 5 × 10⁻⁶. 18 ~10×10 18 cm -3 .

[0032] Furthermore, the thickness of the first n-GaN layer is 0.5–2 μm.

[0033] Furthermore, the thickness of the n-AlGaN layer is 10–100 nm.

[0034] Furthermore, the growth of multi-period Si-doped NGaN layers is carried out in a reaction chamber at a temperature of 950–1050 °C, a pressure of 150–200 Torr, a rotation speed of 1200 r / min, a carrier gas of H2, and a V / III molar ratio of 100–300.

[0035] Furthermore, the thickness of the multi-period Si-doped NGaN layer is 1.5–2 μm, and the number of periods is 50–100.

[0036] As can be seen from the above description, the periodic growth of multi-period Si-doped GaN can reduce stress.

[0037] Furthermore, the growth of the superlattice InGaN / GaN stress-relieving layer is carried out in a reaction chamber at a temperature of 850–950 °C, a pressure of 150–200 Torr, a rotation speed of 600 r / min, a carrier gas of H2, and a V / III molar ratio of 1000–5000.

[0038] Furthermore, the number of periods in the superlattice InGaN / GaN stress relief layer is 5 to 10.

[0039] As can be seen from the above description, superlattice InGaN / GaN can reduce dislocations and stress caused by N-layer growth.

[0040] Furthermore, the growth of the u-AlGaN layer is carried out in a reaction chamber at a temperature of 900–950 °C, a pressure of 200 Torr, a rotation speed of 600 r / min, and a carrier gas of H2.

[0041] Furthermore, the growth of the low-temperature Mg-doped first p-GaN layer was carried out in a reaction chamber at a temperature of 750–800 °C, a pressure of 200 Torr, a rotation speed of 600 r / min, a carrier gas of H2, and a doping concentration of 5 × 10⁻⁶. 19 ~1.5×10 20 cm -3 .

[0042] Further, the growth of the p-AlGaN layer is performed in a reaction chamber with a temperature of 950-1000℃, a pressure of 100-150Torr, a rotation speed of 1000r / min, a carrier gas of H2, and a Mg doping concentration of 1x10 18 -2x10 20 cm -3 , and an Al doping concentration of 1x10 19 -1x10 21 cm -3 .

[0043] Further, the thickness of the p-AlGaN layer is 10-100nm.

[0044] As can be seen from the above description, the u-AlGaN layer is the first electron blocking layer, and the p-AlGaN layer is the second blocking layer, which can inhibit the overflow of electrons.

[0045] Further, the growth of the high-temperature Mg-doped second p-GaN layer is performed in a reaction chamber with a temperature of 700-1000℃, a doping concentration of 1x10 18 -1x10 20 cm -3 .

[0046] Further, the thickness of the high-temperature Mg-doped second p-GaN layer is 10-50nm.

[0047] As can be seen from the above description, the low-temperature Mg-doped first p-GaN layer and the high-temperature Mg-doped second p-GaN layer can ensure good ohmic contact with the reflective layer and the electrode.

[0048] Another technical solution of the present application is a GaN-based Mini LED epitaxial structure prepared by the above preparation method.

[0049] Please refer to Figure 1 , the embodiment one of the present application is:

[0050] A preparation method of a GaN-based Mini LED epitaxial structure, comprising the following steps:

[0051] S1: Put the AlN substrate 1 into the reaction chamber of the metal organic chemical vapor deposition device.

[0052] S2: Set the temperature of the reaction chamber to 800℃, the pressure to 200Torr, the rotation speed to 1000r / min, the carrier gas to H2, and the V / Ⅲ molar ratio to 70, and grow a 0.05um AlGaN / GaN buffer layer 2 on the AlN substrate 1.

[0053] S3: Set the temperature of the reaction cavity to 1000 °C, the pressure to 200 Torr, the rotation speed to 1000 r / min, the carrier gas to H2, the V / III molar ratio to 200, and grow a 2 μm high-temperature undoped UGaN layer 3 on the AlGaN / GaN buffer layer 2.

[0054] S4: Set the temperature of the reaction cavity to 1000 °C, the pressure to 200 Torr, the rotation speed to 1000 r / min, the carrier gas to H2, the V / III molar ratio to 200, and the doping concentration to 7 x 10 18 cm -3 , and grow a 0.6 μm first n-GaN layer 4 on the high-temperature undoped UGaN layer 3.

[0055] S5: Grow a 50 nm n-AlGaN layer 5 on the first n-GaN layer 4.

[0056] S6: Set the temperature of the reaction cavity to 1000 °C, the pressure to 160 Torr, the rotation speed to 1200 r / min, the carrier gas to H2, the V / III molar ratio to 200, and grow a 1.7 μm multi-period Si-doped NGaN layer 6 on the n-AlGaN layer 5, the multi-period Si-doped NGaN layer 6 having a period number of 50-100.

[0057] S7: Set the temperature of the reaction cavity to 900 °C, the pressure to 170 Torr, the rotation speed to 600 r / min, the carrier gas to H2, the V / III molar ratio to 2000, and grow a superlattice InGaN / GaN stress release layer 7 having a period number of 7 on the multi-period Si-doped NGaN layer 6.

[0058] S8: Set the temperature of the reaction cavity to 800-950 °C, and the well-barrier temperature difference (the barrier layer temperature is higher) to 120 °C, and grow an active region multi-quantum well layer 8 on the superlattice InGaN / GaN stress release layer 7; the active region multi-quantum well layer comprises a stack of 8 groups of well layers and barrier layers; the well layer is GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN (0.05 < x1 < 0.15, 0.15 < x2 < 0.3) with a thickness of 8 nm; the barrier layer is GaN / Al y1 Ga 1－y1 N (0.1 < y1 < 0.3) with a thickness of 10 nm; the thickness of In x2 Ga 1－x2 N in the well layer is 1-3.5 nm; the barrier layer uses Si-doped GaN.

[0059] The pressure of the reaction cavity is 170 Torr and the rotating speed is 400 r / min when growing the potential well layer, and the pressure of the reaction cavity is 220 Torr and the rotating speed is 650 r / min when growing the potential barrier layer.

[0060] S9: setting the temperature of the reaction cavity as 920℃, the pressure as 200 Torr, the rotating speed as 600 r / min, the carrier gas as H2, and growing a u-AlGaN layer 9 on the active region multi-quantum well layer 8.

[0061] S10: setting the temperature of the reaction cavity as 780℃, the pressure as 200 Torr, the rotating speed as 600 r / min, the carrier gas as H2, and the doping concentration as 6×10 19 cm -3 , and growing a low-temperature Mg-doped first p-GaN layer 10 on the u-AlGaN layer 9.

[0062] S11: setting the temperature of the reaction cavity as 980℃, the pressure as 120 Torr, the rotating speed as 1000 r / min, the carrier gas as H2, the Mg doping concentration as 2×10 18 cm -3 , and the Al doping concentration as 2×10 19 cm -3 , and growing a 50-nm p-AlGaN layer 11 on the first p-GaN layer 10.

[0063] S12: setting the temperature of the reaction cavity as 800℃, the doping concentration as 1×10 19 cm -3 , and growing a 30-nm high-temperature Mg-doped second p-GaN layer 12 on the p-AlGaN layer 11.

[0064] Embodiment two of the application is:

[0065] A preparation method of a GaN-based Mini LED epitaxial structure, comprising the following steps:

[0066] S1: placing an AlN substrate 1 into a reaction cavity of a metal organic chemical vapor deposition device.

[0067] S2: setting the temperature of the reaction cavity as 700℃, the pressure as 100 Torr, the rotating speed as 800 r / min, the carrier gas as H2, and the V / Ⅲ molar ratio as 60, and growing a 0.005-um AlGaN / GaN buffer layer 2 on the AlN substrate 1.

[0068] S3: setting the temperature of the reaction cavity as 1050℃, the pressure as 150 Torr, the rotating speed as 800 r / min, the carrier gas as H2, and the V / Ⅲ molar ratio as 100, and growing a 1-μm high-temperature undoped UGaN layer 3 on the AlGaN / GaN buffer layer 2.

[0069] S4: set the temperature of the reaction chamber to 1050 °C, the pressure to 150 Torr, the rotation speed to 800 r / min, the carrier gas to H2, the V / III molar ratio to 100, and the doping concentration to 5 x 1019 cm-3. 18 -3 A first n-GaN layer 4 of 0.5 μm is grown on the high-temperature non-doped UGaN layer 3.

[0070] S5: an n-AlGaN layer 5 of 10 nm is grown on the first n-GaN layer 4.

[0071] S6: set the temperature of the reaction chamber to 950 °C, the pressure to 150 Torr, the rotation speed to 1200 r / min, the carrier gas to H2, the V / III molar ratio to 100, and grow a multi-period Si-doped NGaN layer 6 of 1.5 μm on the n-AlGaN layer 5.

[0072] S7: set the temperature of the reaction chamber to 850 °C, the pressure to 150 Torr, the rotation speed to 600 r / min, the carrier gas to H2, the V / III molar ratio to 1000, and grow a superlattice InGaN / GaN stress release layer 7 on the multi-period Si-doped NGaN layer 6.

[0073] S8: set the temperature of the reaction chamber to 800-950 °C, the well-barrier temperature difference (the temperature of the barrier layer is higher) to 120 °C, and grow an active region multi-quantum well layer 8 on the superlattice InGaN / GaN stress release layer 7; the active region multi-quantum well layer comprises a stack of 1 group of well layers and barrier layers; the well layer is GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN (0.05 < x1 < 0.15, 0.15 < x2 < 0.3) with a thickness of 5 nm; the barrier layer is GaN / Al y1 Ga 1－y1 N (0.1 < y1 < 0.3) with a thickness of 5 nm; the thickness of In x2 Ga 1－x2 N in the well layer is 1-3.5 nm; the barrier layer is Si-doped GaN.

[0074] When the well layer is grown, the pressure of the reaction chamber is 150 Torr, the rotation speed is 350 r / min, and the carrier gas is H2; when the barrier layer is grown, the pressure of the reaction chamber is 200 Torr, the rotation speed is 600 r / min, and the carrier gas is H2.

[0075] S9: set the temperature of the reaction chamber to 900 °C, the pressure to 200 Torr, the rotation speed to 600 r / min, the carrier gas to H2, and grow a u-AlGaN layer 9 on the active region multi-quantum well layer 8. ​

[0076] S10: set the temperature of the reaction chamber to 750 DEG C, the pressure to 200 Torr, the rotation speed to 600 r / min, the carrier gas to H2, and the doping concentration to 5*10 19 cm -3 A low-temperature Mg-doped first p-GaN layer 10 is grown on the u-AlGaN layer 9.

[0077] S11: set the temperature of the reaction chamber to 950 DEG C, the pressure to 100 Torr, the rotation speed to 1000 r / min, the carrier gas to H2, and the Mg doping concentration to 1*10 18 cm -3 , and the Al doping concentration to 1*10 19 cm -3 A 10-nm p-AlGaN layer 11 is grown on the first p-GaN layer 10.

[0078] S12: set the temperature of the reaction chamber to 700 DEG C, and the doping concentration to 1*10 18 cm -3 A high-temperature Mg-doped second p-GaN layer 12 is grown on the p-AlGaN layer 11.

[0079] Embodiment three of the present application is:

[0080] A preparation method of a GaN-based Mini LED epitaxial structure, comprising the following steps:

[0081] S1: an AlN substrate 1 is placed into a reaction chamber of a metal organic chemical vapor deposition device.

[0082] S2: set the temperature of the reaction chamber to 900 DEG C, the pressure to 300 Torr, the rotation speed to 1200 r / min, the carrier gas to H2, the V / III molar ratio to 100, and grow a 0.1-um AlGaN / GaN buffer layer 2 on the AlN substrate 1.

[0083] S3: set the temperature of the reaction chamber to 1100 DEG C, the pressure to 300 Torr, the rotation speed to 1200 r / min, the carrier gas to H2, the V / III molar ratio to 300, and grow a 3-um high-temperature undoped UGaN layer 3 on the AlGaN / GaN buffer layer 2.

[0084] S4: set the temperature of the reaction chamber to 1100 DEG C, the pressure to 300 Torr, the rotation speed to 1200 r / min, the carrier gas to H2, the V / III molar ratio to 300, and the doping concentration to 10*10 18 cm -3 , and grow a 2-um first n-GaN layer 4 on the high-temperature undoped UGaN layer 3.

[0085] S5: A 100 nm n-AlGaN layer 5 is grown on the first n-GaN layer 4.

[0086] S6: The temperature of the reaction chamber is set to 1050 °C, the pressure to 200 Torr, the rotation speed to 1200 r / min, the carrier gas to H2, and the V / III molar ratio to 300. A 2 μm multi-period Si-doped n-GaN layer 6 is grown on the n-AlGaN layer 5.

[0087] S7: The temperature of the reaction chamber is set to 950 °C, the pressure to 200 Torr, the rotation speed to 600 r / min, the carrier gas to H2, and the V / III molar ratio to 5000. A superlattice InGaN / GaN stress release layer 7 is grown on the multi-period Si-doped n-GaN layer 6.

[0088] S8: The temperature of the reaction chamber is set to 800-950 °C, and the well-barrier temperature difference (the temperature of the barrier layer is higher) is set to 120 °C. An active region multi-quantum well layer 8 is grown on the superlattice InGaN / GaN stress release layer 7; the active region multi-quantum well layer comprises a stack of 10 groups of well layers and barrier layers; the well layer is GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN (0.05 < x1 < 0.15, 0.15 < x2 < 0.3) with a thickness of 10 nm; the barrier layer is GaN / Al y1 Ga 1－y1 N (0.1 < y1 < 0.3) with a thickness of 15 nm; the thickness of In x2 Ga 1－x2 N in the well layer is 1-3.5 nm; the barrier layer is Si-doped GaN.

[0089] When the well layer is grown, the pressure of the reaction chamber is 170 Torr, the rotation speed is 400 r / min, and the carrier gas is H2; when the barrier layer is grown, the pressure of the reaction chamber is 220 Torr, the rotation speed is 650 r / min, and the carrier gas is H2.

[0090] S9: The temperature of the reaction chamber is set to 950 °C, the pressure to 200 Torr, the rotation speed to 600 r / min, and the carrier gas to H2. A u-AlGaN layer 9 is grown on the active region multi-quantum well layer 8.

[0091] S10: The temperature of the reaction chamber is set to 800 °C, the pressure to 200 Torr, the rotation speed to 600 r / min, the carrier gas to H2, and the doping concentration to 1.5 x 10 20 cm -3 A low-temperature Mg-doped first p-GaN layer 10 is grown on the u-AlGaN layer 9.

[0092] S11: set the temperature of the reaction cavity to 1000 DEG C, the pressure to 150 Torr, the rotation speed to 1000 r / min, the carrier gas to H2, the Mg doping concentration to 2*10 20 cm -3 , the Al doping concentration to 1*10 21 cm -3 , and grow a 100-nm p-AlGaN layer 11 on the first p-GaN layer 10.

[0093] S12: set the temperature of the reaction cavity to 1000 DEG C, the doping concentration to 1*10 20 cm -3 , and grow a 50-nm high-temperature Mg-doped second p-GaN layer 12 on the p-AlGaN layer 11.

[0094] The comparative example one of the present application is:

[0095] The difference between the comparative example one and the example one is that the pressure of the reaction cavity is 200 Torr and the rotation speed is 550 r / min when growing the potential well layer and the potential barrier layer.

[0096] The epitaxial wafer of the example one is sequentially subjected to epitaxial wafer cleaning -> MESA -> CBL -> ITO -> MET -> PV -> electrical alloying -> COW testing -> grinding and thinning -> cleaving -> sorting and full testing to form LED chips, the LED chips are made into 3*6-mil green light core particles, 5MA point testing is performed, and performance testing is performed, the testing items are shown in Table 1, and the testing results are shown in Table 2.

[0097] Table 1

[0098] Item Type Test Condition Pass / Fail Criteria Yield Requirement VF1 Avg 5 mA 2.5 < vf < 2.9 ≥85％ VF3 Avg 0.001 mA ≥2.2V ≥85％ VZ Min 10 uA ≥35 ≥85％ IR Max -10V 1 ≥85％ IV (MW) Avg 5 mA 3 < IV < 5 ≥85％ WLD Avg 5 mA 520 < wd < 530 ≥85％ WLD_STD Max / ≤3 ≥85％ ESD Min 500V ≥90％

[0099] Table 2

[0100]

[0101] As shown in Table 1, the light efficiency and uniformity of the LED chip prepared by using the high-uniformity high-light-efficiency GaN-based Mini LED epitaxial wafer of the present application are obviously improved.

[0102] In summary, the preparation method of the high-uniformity high-light-efficiency GaN-based Mini LED epitaxial wafer of the application grows a plurality of periods of potential well layers and potential barrier layers alternately by using the method of slow long well and fast long barrier for the active region multi-quantum well layer. When growing the potential well layer, low pressure and low rotation speed are used, the growth rate is slow, and the In source can be uniformly distributed on the epitaxial wafer; when growing the potential barrier layer, high pressure and high rotation speed are used, the growth rate is fast, and the In precipitation can be prevented, and the light-emitting efficiency is improved. The active region multi-quantum well layer is grown repeatedly for stress release by using this method, the stress accumulation is reduced, the stress release effect is better, and thus the wafer warping can be greatly improved, the Stark effect can be effectively alleviated, the In source can be uniformly distributed on the epitaxial wafer during the growth of the active layer, and the consistency of various parameters of the LED is better.

[0103] The above description is only an embodiment of the application, and does not limit the patent scope of the application, and any equivalent transformation or direct or indirect application in the related technical field by using the content of the specification and drawings of the application is also included in the patent protection scope of the application.

Claims

1. A method for preparing a GaN-based Mini LED epitaxial structure, characterized in that, When growing the active region multi-quantum well layer, the temperature of the reaction cavity is set to 800-950℃, and the temperature difference between the well and the barrier is 100-150℃, and the potential well layer and the potential barrier layer are alternately grown; When growing the potential well layer, the pressure of the reaction cavity is 100-190Torr, the rotation speed is 300-500r / min, and the carrier gas is H2; when growing the potential barrier layer, the pressure of the reaction cavity is 200-400Torr, and the rotation speed is 600-700r / min; The potential well layer is GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN, with a thickness of 5-10 nm; the potential barrier layer is GaN / Al y1 Ga 1－y1 N, with a thickness of 5-15 nm; In x2 Ga 1－x2 N is 1-3.5 nm; The active region multi-quantum well layer comprises 1-10 groups of potential well layers and potential barrier layers. The potential barrier layer is Si-doped GaN; The content of x1 and the content of x2 are adjusted by temperature, pressure and rotation speed, and the In content is designed by adjusting the quantum well segmented growth structure and temperature, so as to reduce the well-barrier mismatch, thereby relieving the Stark effect, reducing dislocations and improving the light-emitting efficiency.

2. The preparation method of the GaN-based Mini LED epitaxial structure according to claim 1, characterized in that, An AlGaN / GaN buffer layer, a high-temperature undoped UGaN layer, a first n-GaN layer, an n-AlGaN layer, a multi-period Si-doped NGaN layer, a superlattice InGaN / GaN stress release layer, an active region multi-quantum well layer, a u-AlGaN layer, a low-temperature Mg-doped first p-GaN layer, a p-AlGaN layer and a high-temperature Mg-doped second p-GaN layer are sequentially grown on an AlN substrate.

3. The preparation method of the GaN-based Mini LED epitaxial structure according to claim 2, characterized in that, The multi-period Si-doped NGaN layer is grown in a reaction cavity, the temperature of the reaction cavity is 950-1050℃, the pressure is 150-200Torr, the rotation speed is 1200r / min, the carrier gas is H2, and the V / Ⅲ molar ratio is 100-300.

4. The preparation method of the GaN-based Mini LED epitaxial structure according to claim 2, characterized in that, The superlattice InGaN / GaN stress release layer is grown in a reaction cavity, the temperature of the reaction cavity is 850-950℃, the pressure is 150-200Torr, the rotation speed is 600r / min, the carrier gas is H2, and the V / Ⅲ molar ratio is 1000-5000.

5. The preparation method of the GaN-based Mini LED epitaxial structure according to claim 2, characterized in that, The low-temperature Mg-doped first p-GaN layer is grown in a reaction cavity with a temperature of 750-800 °C, a pressure of 200 Torr, a rotation speed of 600 r / min, H2 as the carrier gas, and a doping concentration of 5x10 19 -1.5x10 20 cm -3 .

6. A GaN-based Mini LED epitaxial structure prepared by the preparation method according to any one of claims 1-5.

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