GaN-based micro led epitaxial structure and growth method and vapor deposition device thereof

Abstract

The application relates to the fields of semiconductor photoelectric devices and semiconductor display manufacturing, in particular to a GaN-based Micro LED epitaxial structure and a growth method and a vapor deposition device thereof. The GaN-based Micro LED epitaxial structure comprises a stress release layer, the stress release layer comprises a first group of InGaN / GaN structures, a second group of InGaN / GaN structures and a third group of InGaN / GaN structures which are sequentially stacked from bottom to top; the GaN-based Micro LED epitaxial structure is designed to contain the stress release layer of the three groups of InGaN / GaN structures, the thicknesses and the doping concentrations of the three groups of InGaN / GaN structures are all different, the stress release layer is optimized, the V-Pits with appropriate sizes are formed with the linear thread dislocations as the centers, the non-radiation recombination of the electron-hole pairs at the defects can be inhibited, and the light-emitting efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor optoelectronic devices and semiconductor display manufacturing, in particular to a GaN-based Micro LED epitaxial structure and a growth method and vapor deposition device thereof. BACKGROUND

[0002] Light emitting diodes (LEDs) are widely used in lighting and displays, and LEDs emit light by releasing energy through the recombination of holes and electrons, converting electrical energy into light energy. With the development of society, the industry has increasingly high requirements for the display brightness, contrast ratio and resolution of LEDs, and micro light emitting diodes (Micro LEDs) have emerged as the times require. Micro LEDs have the characteristics of thin film, miniaturization and array, and can reduce the pixel distance from millimeter level to micrometer level, showing great advantages in contrast ratio, brightness and reliability.

[0003] Chinese patent CN113270525A discloses a preparation method of a green light epitaxial structure, which improves the light-emitting efficiency by improving the well-barrier mismatch of the multi-period quantum well of GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN different In component structures. However, the consistency of the wavelength, light-emitting intensity and color of the LED is poor when the active region is grown by the above method, which is not suitable for Micro LEDs with high consistency requirements and will seriously affect the display effect of the Micro LED. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a GaN-based Micro LED epitaxial structure with high light efficiency and high uniformity, and a growth method and vapor deposition device thereof.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a GaN-based Micro LED epitaxial structure, comprising a stress release layer, the stress release layer comprising a first group of InGaN / GaN structures, a second group of InGaN / GaN structures and a third group of InGaN / GaN structures stacked in order from bottom to top.

[0006] The doping concentration of In in the first group of InGaN / GaN structures is 1E+18-2E+20 atom / cm 3 , the doping concentration of Si is 1E+18-2E+20 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 2-15 nm.

[0007] In the second group of InGaN / GaN structures, the In doping concentration is 5E+17 to 1E+19 atoms / cm². 3 The doping concentration of Si is 5E+17 to 1E+18 atoms / cm³. 3 The thickness of GaN in a single InGaN / GaN structure is 3.2–24 nm;

[0008] The In doping concentration in the third group of InGaN / GaN structures is 1E+17~5E+18 atom / cm³. 3 The doping concentration of Si is 5E+16 to 5E+17 atoms / cm³. 3 The thickness of GaN in a single InGaN / GaN structure ranges from 2.6 to 19.5 nm.

[0009] Another technical solution adopted in this invention is as follows: the growth method of the above-mentioned GaN-based Micro LED epitaxial structure, wherein the stress relief layer is grown in a vapor deposition apparatus. When growing the first group of InGaN / GaN structures, the temperature of the vapor deposition apparatus is 800-850°C and the flow rate of TMIn is 500-600 mL / s; when growing the second group of InGaN / GaN structures, the temperature of the vapor deposition apparatus is 850-900°C and the flow rate of TMIn is 600-700 mL / s; when growing the third group of InGaN / GaN structures, the temperature of the vapor deposition apparatus is 900-950°C and the flow rate of TMIn is 700-800 mL / s.

[0010] Another technical solution adopted by the present invention is: a vapor deposition apparatus for growing the above-mentioned GaN-based MicroLED epitaxial structure, characterized in that it includes a top cover, a graphite disk, a heat insulation plate and a heating wire arranged sequentially from top to bottom, the top cover has a through hole in the center, the through hole is connected to a gas flow controller through a pipeline, and a substrate with a diameter of 8 inches is placed in the graphite disk.

[0011] The beneficial effects of the present invention are as follows: The GaN-based Micro LED epitaxial structure design of the present invention includes three sets of InGaN / GaN structure stress relief layers. The thickness and doping concentration of the three sets of InGaN / GaN structures are different. The stress relief layer is optimized to form V-Pits of appropriate size centered on thread dislocations, which can suppress nonradiative recombination of electron-hole pairs at defects and improve luminous efficiency. Attached Figure Description

[0012] Fig. 1 The diagram shown is a schematic diagram of the vapor deposition apparatus according to Embodiment 5 of the present invention;

[0013] Fig. 2Fig. 1 is a front view of a top cover in a vapor deposition device of the present application;

[0014] Fig. 3 Fig. 2 is a top view of a top cover in a vapor deposition device of the present application;

[0015] BRIEF DESCRIPTION OF DRAWINGS

[0016] 1. top cover; 2. graphite disc; 21. storage groove; 3. heat insulation plate; 4. heating wire; 5. rotating shaft; 6. pipeline. DETAILED DESCRIPTION

[0017] To make the technical contents, purposes and effects of the present application clear, the following will be described in detail in combination with the embodiments and the accompanying drawings.

[0018] A GaN-based Micro LED epitaxial structure, comprising a stress release layer, the stress release layer comprising a first group of InGaN / GaN structures, a second group of InGaN / GaN structures and a third group of InGaN / GaN structures which are sequentially stacked from bottom to top.

[0019] The doping concentration of In in the first group of InGaN / GaN structures is 1E+18-2E+20 atom / cm 3 , the doping concentration of Si is 1E+18-2E+20 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 2-15 nm; preferably, the thickness of GaN in a single InGaN / GaN structure is 5-8 nm.

[0020] The doping concentration of In in the second group of InGaN / GaN structures is 5E+17-1E+19 atom / cm 3 , the doping concentration of Si is 5E+17-1E+18 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 3.2-24 nm; preferably, the thickness of GaN in a single InGaN / GaN structure is 8-15 nm.

[0021] The doping concentration of In in the third group of InGaN / GaN structures is 1E+17-5E+18 atom / cm 3 , the doping concentration of Si is 5E+16-5E+17 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 2.6-19.5 nm; preferably, the thickness of GaN in a single InGaN / GaN structure is 6-12 nm.

[0022] From the above description, the beneficial effects of the present application are that: the V-pits (V-shaped pits) are too small, which may cause the sidewall thin well band gap to be too small, unable to prevent electron-hole pairs from non-radiative recombination at defects, thereby reducing the light efficiency; and the V-pits are too large, which causes the effective light-emitting area of the C face (polar face) to decrease, thereby reducing the brightness. The GaN-based Micro LED epitaxial structure of the present application is designed with a specific stress release layer, which includes three groups of InGaN / GaN structures, the thickness and the doping TMIn (trimethylindium) and SiH4 (silane) concentrations of the three groups of InGaN / GaN structures are all different, forming V-pits with a proper size centered on a threading dislocation, which can inhibit the non-radiative recombination of electron-hole pairs at defects and improve the light-emitting efficiency.

[0023] Further, the cycle number of a single InGaN / GaN structure in the first group, the second group and the third group of InGaN / GaN structures is 3-6.

[0024] Further, the thickness of InGaN of a single InGaN / GaN structure in the first group, the second group and the third group of InGaN / GaN structures is 1-5 nm.

[0025] From the above description, the thickness is proportional to the size of the V-pits, the V-pits are too large, which causes the defects to be difficult to fill in, and the V-pits are too small, which causes the brightness to decrease, and by limiting the cycle number and the thickness of a single InGaN / GaN structure, the size of the V-pits can be adjusted.

[0026] The GaN-based Micro LED epitaxial structure includes, from bottom to top, an AlN substrate, an AlGaN / GaN buffer layer, a high-temperature undoped UGaN layer, a high-temperature doped NGaN layer, an n-AlGaN layer, a multi-period Si-doped NGaN layer, a stress release layer, a multi-quantum well active region layer, a first electron blocking layer, a first p-GaN layer, a p-AlGaN layer and a second p-GaN layer.

[0027] Another technical solution adopted by the application is that: the growth method of the GaN-based Micro LED epitaxial structure, the stress release layer is grown in a vapor deposition device, when growing the first group of InGaN / GaN structure, the temperature of the vapor deposition device is 800-850 DEG C, the flow rate of TMIn is 500-600 ml / s; when growing the second group of InGaN / GaN structure, the temperature of the vapor deposition device is 850-900 DEG C, the flow rate of TMIn is 600-700 ml / s; when growing the third group of InGaN / GaN structure, the temperature of the vapor deposition device is 900-950 DEG C, the flow rate of TMIn is 700-800 ml / s.

[0028] As can be known from the above description, the thickness, temperature and doped TMIn and SiH4 concentration of the three groups of InGaN / GaN structure in the stress release layer of the application are all different, the V-Pits with appropriate size centered on the linear thread dislocation are formed, so that the non-radiative recombination of electron-hole pairs at defects is inhibited, and the luminous efficiency is improved.

[0029] Further, the pressure of the vapor deposition device when growing the stress release layer is 150-200 Torr, and the V / III molar ratio is 1000-5000.

[0030] Further, the AlN substrate is placed in the vapor deposition device, the pressure of the vapor deposition device is set to 50-100 Torr, the rotation speed is set to 400-600 rpm, and N2, H2 and NH3 are simultaneously introduced for 5-15 minutes; then, the AlGaN / GaN buffer layer, the high-temperature undoped UGaN layer, the high-temperature doped NGaN layer, the n-AlGaN layer, the multi-period Si-doped NGaN layer, the stress release layer, the multi-quantum well active region layer, the first electron blocking layer, the first p-GaN layer, the p-AlGaN layer and the second p-GaN layer are sequentially grown on the AlN substrate.

[0031] As can be known from the above description, the AlN substrate is treated by simultaneously introducing N2, H2 and NH3 under the condition of low pressure and low speed, which is different from the traditional high pressure and high temperature and hydrogen-only treatment method, and this special process can clean the surface of the AlN substrate and obtain thinner and higher lattice quality AlN at the same time.

[0032] Further, when growing the multi-quantum well active region layer, the temperature of the vapor deposition device is set to 850-950 DEG C, the well / barrier temperature difference is 100-150 DEG C, and H2 is used as the carrier gas; the well GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2N / GaN, under pressure of 200-400 Torr and rotation speed of 600-700 rpm y1 Ga 1－y1 N.

[0033] From the above description, it can be seen that the multi-quantum well active region layer adopts GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN, GaN / Al y1 Ga 1－y1 N different In component structures, x1 content and x2 content can be adjusted by temperature to reduce well-barrier mismatch, thereby relieving the Stark effect, and the quantum barrier adopts Si-doped GaN, which can reduce dislocations. The multi-quantum well active region layer of the present application has a slow growth rate when growing a long well, so that the In source is uniformly distributed on the epitaxial wafer, and has a slow growth rate when growing a long barrier to prevent In precipitation and improve light emitting efficiency. The multi-quantum well active region layer includes a plurality of periodically grown wells and barriers, can repeatedly release stress, reduce stress accumulation, enhance stress release effect, greatly improve the warping phenomenon of the epitaxial wafer, so that the In source can be uniformly distributed on the epitaxial wafer during the growth of the subsequent active layer, and improve the wavelength consistency, light emitting intensity consistency and color consistency of the LED.

[0034] Further, when growing the second p-GaN layer, the pressure of the vapor deposition device is first set to 400-600 Torr to grow p-GaN with a thickness of 10-50 nm, and then the pressure of the vapor deposition device is set to 100-200 Torr to grow p-GaN with a thickness of 10-50 nm.

[0035] From the above description, it can be seen that when growing the second p-GaN layer, the high-pressure p-GaN is first grown, and then the low-pressure p-GaN is grown, which can improve the consistency of the central region brightness.

[0036] A GaN-based Micro LED epitaxial structure includes a second p-GaN layer.

[0037] Further, when growing the second p-GaN layer, the pressure of the vapor deposition device is first set to 400-600 Torr to grow p-GaN with a thickness of 10-50 nm, and then the pressure of the vapor deposition device is set to 100-200 Torr to grow p-GaN with a thickness of 10-50 nm.

[0038] Further, the Mg doping concentration of the second p-GaN layer is 1x10 18 -1x10 20 cm -3 .

[0039] As Figs. 1-3 shown, another technical solution adopted by the application is: a vapor deposition device for growing the GaN-based Micro LED epitaxial structure, characterized by comprising, from top to bottom, a top cover, a graphite disc, a heat insulation plate and a heating wire, a through hole is arranged at the center of the top cover, the through hole is connected to a gas flow controller through a pipeline, and an 8-inch diameter substrate is placed in the graphite disc.

[0040] As can be seen from the above description, the application increases a shower-like structure at the center of the top cover, which can ensure that chemical deposition also occurs in the central area V / III, improve the uniformity of chemical deposition, and be beneficial to growing large-size epitaxial wafers.

[0041] Further, the number of through holes is two, one through hole is connected to N2 and / or H2 and / or NH3, and the other through hole is connected to the MO source.

[0042] Further, the distance between the top cover and the graphite disc is 25-30 cm.

[0043] As can be seen from the above description, the distance between the top cover and the graphite disc is reduced by 5-10 cm, which can reduce the eddy current, make the gas flow more uniform, and improve the uniformity of chemical deposition.

[0044] Embodiment one of the application is: a growth method of a GaN-based Micro LED epitaxial structure, the steps are as follows:

[0045] S1: Place an 8-inch diameter AlN substrate in a vapor deposition device, set the pressure of the vapor deposition device to 80 Torr, the rotation speed to 500 rpm, and simultaneously pass 30 L / min of N2, 300 L / min of H2 and 20 L / min of NH3, and pass the three gases for 10 minutes;

[0046] S2: Grow an AlGaN / GaN buffer layer on the AlN substrate;

[0047] Set the temperature of the vapor deposition device to 800℃, the pressure to 200 Torr, and the rotation speed to 1000 rpm, use H2 carrier gas, and the V / III molar ratio is 80.

[0048] S3: Grow a high-temperature undoped UGaN layer with a thickness of 2 microns on the AlGaN / GaN buffer layer;

[0049] Set the temperature of the vapor deposition device to 10600℃, the pressure to 200 Torr, and the rotation speed to 1000 rpm, use H2 carrier gas, and the V / III molar ratio is 80.

[0050] S4: A 1 μm thick Si doping concentration of 7 × 10⁻⁶ Si is grown on a high-temperature undoped UGaN layer. 18 cm -3 High-temperature doped NGaN layer;

[0051] The vapor deposition apparatus was set to a temperature of 1070℃, a pressure of 200 Torr, a rotation speed of 1000 rpm, and H2 as the carrier gas with a V / III molar ratio of 200.

[0052] S5: A 50 nm thick Al doping concentration of 1E+17 atom / cm² is grown on a high-temperature doped NGaN layer. -3 n-AlGaN layer;

[0053] The vapor deposition apparatus was set to a temperature of 1000℃, a pressure of 100 Torr, a rotation speed of 1000 rpm, and H2 as the carrier gas with a V / III molar ratio of 100.

[0054] S6: A multi-period Si-doped NGaN layer with a thickness of 1.8 μm is grown on the n-AlGaN layer;

[0055] The vapor deposition apparatus was set to a temperature of 1000℃, a pressure of 170 Torr, a rotation speed of 1200 rpm, H2 carrier gas, a V / III molar ratio of 200, and a cycle number of 80.

[0056] S7: Growing a stress-relieving layer on a multi-period Si-doped NGaN layer;

[0057] The vapor deposition apparatus was set to a pressure of 180 Torr, a rotation speed of 600 rpm, and H2 as the carrier gas with a V / III molar ratio of 3000. The temperature was then set to 830°C, and the TMIn flow rate was 550 mL / s. The first InGaN / GaN structure was grown with an In doping concentration of 1E+19 atom / cm³. 3 The doping concentration of Si is 1E+19 atoms / cm³. 3 The GaN thickness in a single InGaN / GaN structure is 5 nm. The vapor deposition apparatus is set to a temperature of 870 °C and a TMIn flow rate of 650 mL / s to grow a second InGaN / GaN structure. The In doping concentration in the second InGaN / GaN structure is 1E+18 atom / cm³. 3 The doping concentration of Si is 6E+17 atoms / cm³. 3, the thickness of GaN in a single InGaN / GaN structure is 8 nm; the temperature of the vapor deposition device is set to 920℃, the flow rate of TMIn is 750 ml / s, a third group of InGaN / GaN structures is grown, the doping concentration of In in the third group of InGaN / GaN structures is 1E+18 atom / cm 3 , the doping concentration of Si is 1E+17 atom / cm 3 , the thickness of GaN in a single InGaN / GaN structure is 6.5 nm; the cycle number of a single InGaN / GaN structure in the first group of InGaN / GaN structures, the second group of InGaN / GaN structures and the third group of InGaN / GaN structures is 4, and the thickness of InGaN is 3 nm.

[0058] S8: growing a multi-quantum well active region layer on the stress release layer;

[0059] The temperature of the vapor deposition device is set to 900℃, the temperature difference between the well and the barrier is 130℃, and H2 is used as the carrier gas; the well GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN is grown at a pressure of 150 Torr and a rotation speed of 400 rpm, the barrier GaN / Al y1 Ga 1－y1 N is grown at a pressure of 300 Torr and a rotation speed of 650 rpm.

[0060] S9: growing a first electron blocking layer on the multi-quantum well active region layer;

[0061] The temperature of the vapor deposition device is set to 920℃, the pressure is 200 Torr, the rotation speed is 600 rpm, H2 is used as the carrier gas, the V / III molar ratio is 200, and the thickness is 8 nm.

[0062] S10: growing a first p-GaN layer with a Mg doping concentration of 1×10 20 cm -3 on the first electron blocking layer;

[0063] The temperature of the vapor deposition device is set to 780℃, the pressure is 200 Torr, and the rotation speed is 600 rpm.

[0064] S11: growing a p-AlGaN layer with a thickness of 50 nm, a Mg doping concentration of 1×10 19 cm -3 , and an Al doping concentration of 1×10 20 cm -3 on the first p-GaN layer;

[0065] The temperature of the vapor deposition device is set to 970 DEG C, the pressure is set to 120 Torr, the rotation speed is set to 1000 rpm, and H2 is used as the carrier gas.

[0066] S12: growing a second p-GaN layer with a Mg doping concentration of 1*10 19 cm -3 on the p-AlGaN layer;

[0067] The temperature of the vapor deposition device is set to 900 DEG C; then the pressure of the vapor deposition device is set to 500 Torr, and a p-GaN layer with a thickness of 30 nm is grown; and then the pressure of the vapor deposition device is set to 150 Torr, and a p-GaN layer with a thickness of 30 nm is grown.

[0068] Embodiment two of the application is a growth method of a GaN-based Micro LED epitaxial structure, and the steps are as follows:

[0069] S1: placing an AlN substrate with a diameter of 8 inches in a vapor deposition device, setting the pressure of the vapor deposition device to 50 Torr, setting the rotation speed to 400 rpm, and simultaneously introducing 10 L / min of N2, 200 L / min of H2 and 10 L / min of NH3 for 5 minutes;

[0070] S2: growing an AlGaN / GaN buffer layer on the AlN substrate;

[0071] The temperature of the vapor deposition device is set to 700 DEG C, the pressure is set to 100 Torr, the rotation speed is set to 800 rpm, H2 is used as the carrier gas, and the V / III molar ratio is 60.

[0072] S3: growing a high-temperature undoped UGaN layer with a thickness of 1 mu m on the AlGaN / GaN buffer layer;

[0073] The temperature of the vapor deposition device is set to 1050 DEG C, the pressure is set to 150 Torr, the rotation speed is set to 800 rpm, H2 is used as the carrier gas, and the V / III molar ratio is 60.

[0074] S4: growing a high-temperature doped NGaN layer with a thickness of 0.5 mu m and a Si doping concentration of 5*10 18 cm -3 on the high-temperature undoped UGaN layer;

[0075] The temperature of the vapor deposition device is set to 1050 DEG C, the pressure is set to 150 Torr, the rotation speed is set to 800 rpm, H2 is used as the carrier gas, and the V / III molar ratio is 100.

[0076] S5: growing a high-temperature doped NGaN layer with a thickness of 10 nm and an Al doping concentration of 1E+17 atom / cm -3n-AlGaN layer;

[0077] The temperature of the vapor deposition device is set to 1000℃, the pressure is set to 100 Torr, the rotation speed is set to 1000 rpm, H2 carrier gas is used, and the V / III molar ratio is set to 100.

[0078] S6: A multi-period Si-doped NGaN layer with a thickness of 1.5 μm is grown on the n-AlGaN layer;

[0079] The temperature of the vapor deposition device is set to 900℃, the pressure is set to 150 Torr, the rotation speed is set to 1200 rpm, H2 carrier gas is used, the V / III molar ratio is set to 100, and the number of periods is set to 80.

[0080] S7: A stress release layer is grown on the multi-period Si-doped NGaN layer;

[0081] The pressure of the vapor deposition device is set to 150 Torr, the rotation speed is set to 600 rpm, H2 carrier gas is used, and the V / III molar ratio is set to 1000; then the temperature of the vapor deposition device is set to 800℃, the flow rate of TMIn is set to 500 mL / s, a first group of InGaN / GaN structures is grown, the doping concentration of In in the first group of InGaN / GaN structures is 1E+18 atom / cm 3 , the doping concentration of Si is 1E+18 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 2 nm; the temperature of the vapor deposition device is set to 850℃, the flow rate of TMIn is set to 600 mL / s, a second group of InGaN / GaN structures is grown, the doping concentration of In in the second group of InGaN / GaN structures is 5E+17 atom / cm 3 , the doping concentration of Si is 5E+17 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 3.2 nm; the temperature of the vapor deposition device is set to 900℃, the flow rate of TMIn is set to 700 mL / s, a third group of InGaN / GaN structures is grown, the doping concentration of In in the third group of InGaN / GaN structures is 1E+17 atom / cm 3 , the doping concentration of Si is 5E+16 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 2.6 nm; the number of cycles of a single InGaN / GaN structure in the first group of InGaN / GaN structures, the second group of InGaN / GaN structures, and the third group of InGaN / GaN structures is 3, and the thickness of InGaN is 1 nm.

[0082] S8: A multi-quantum well active region layer is grown on the stress release layer;

[0083] The temperature of the vapor deposition device is set to 850 DEG C, the temperature difference of the well barrier is 100 DEG C, and H2 is used as the carrier gas; the long-well GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN, the long-barrier GaN / Al y1 Ga 1－y1 N.

[0084] S9: growing a first electron blocking layer on the multi-quantum well active region layer;

[0085] The temperature of the vapor deposition device is set to 900 DEG C, the pressure is set to 200 Torr, the rotation speed is set to 600 rpm, H2 is used as the carrier gas, the V / III molar ratio is set to 200, and the thickness is set to 8 nm.

[0086] S10: growing a first p-GaN layer with a Mg doping concentration of 5*10 19 cm -3 -3 on the first electron blocking layer;

[0087] The temperature of the vapor deposition device is set to 750 DEG C, the pressure is set to 200 Torr, and the rotation speed is set to 600 rpm.

[0088] S11: growing a p-AlGaN layer with a thickness of 10 nm, a Mg doping concentration of 1*10 18 cm -3 -3, and an Al doping concentration of 1*10 19 cm -3 -3 on the first p-GaN layer;

[0089] The temperature of the vapor deposition device is set to 950 DEG C, the pressure is set to 100 Torr, the rotation speed is set to 1000 rpm, and H2 is used as the carrier gas.

[0090] S12: growing a second p-GaN layer with a Mg doping concentration of 1*10 18 cm -3 -3 on the p-AlGaN layer;

[0091] The temperature of the vapor deposition device is set to 800 DEG C; then the pressure of the vapor deposition device is set to 400 Torr, and a p-GaN layer with a thickness of 10 nm is grown; and then the pressure of the vapor deposition device is set to 100 Torr, and a p-GaN layer with a thickness of 10 nm is grown.

[0092] Embodiment three of the application is a growth method of a GaN-based Micro LED epitaxial structure, and the steps are as follows:

[0093] S1: An AlN substrate with a diameter of 8 inches is placed in a vapor deposition device, the pressure of the vapor deposition device is set to 100 Torr, the rotation speed is set to 600 rpm, and 50 L / min of N2, 400 L / min of H2, and 40 L / min of NH3 are introduced into the vapor deposition device for 15 minutes;

[0094] S2: An AlGaN / GaN buffer layer is grown on the AlN substrate;

[0095] The temperature of the vapor deposition device is set to 900°C, the pressure is set to 300 Torr, the rotation speed is set to 1200 rpm, H2 is used as the carrier gas, and the V / III molar ratio is set to 100.

[0096] S3: A high-temperature undoped UGaN layer with a thickness of 3 μm is grown on the AlGaN / GaN buffer layer;

[0097] The temperature of the vapor deposition device is set to 1100°C, the pressure is set to 300 Torr, the rotation speed is set to 1200 rpm, H2 is used as the carrier gas, and the V / III molar ratio is set to 100.

[0098] S4: A high-temperature doped NGaN layer with a thickness of 2 μm and a Si doping concentration of 10 x 1018cm-2 is grown on the high-temperature undoped UGaN layer; 18 cm -3 -2

[0099] The temperature of the vapor deposition device is set to 1100°C, the pressure is set to 300 Torr, the rotation speed is set to 1200 rpm, H2 is used as the carrier gas, and the V / III molar ratio is set to 300.

[0100] S5: An n-AlGaN layer with a thickness of 100 nm and an Al doping concentration of 1E+17 atom / cm-2 is grown on the high-temperature doped NGaN layer; -3 -2

[0101] The temperature of the vapor deposition device is set to 1000°C, the pressure is set to 100 Torr, the rotation speed is set to 1000 rpm, H2 is used as the carrier gas, and the V / III molar ratio is set to 100.

[0102] S6: A multi-period Si-doped NGaN layer with a thickness of 2 μm is grown on the n-AlGaN layer;

[0103] The temperature of the vapor deposition device is set to 1050°C, the pressure is set to 200 Torr, the rotation speed is set to 1200 rpm, H2 is used as the carrier gas, the V / III molar ratio is set to 300, and the number of periods is set to 80.

[0104] S7: A stress release layer is grown on the multi-period Si-doped NGaN layer;

[0105] The pressure of the vapor deposition device is set to 200 Torr, the rotation speed is set to 600 rpm, H2 carrier gas is used, and the V / III mole ratio is set to 5000. Then the temperature of the vapor deposition device is set to 850℃, the flow rate of TMIn is set to 600 ml / s, the first group of InGaN / GaN structures is grown, and the doping concentration of In in the first group of InGaN / GaN structures is 2E+20 atom / cm 3 , the doping concentration of Si is 2E+20 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 15 nm. The temperature of the vapor deposition device is set to 900℃, the flow rate of TMIn is set to 700 ml / s, the second group of InGaN / GaN structures is grown, the doping concentration of In in the second group of InGaN / GaN structures is 1E+19 atom / cm 3 , the doping concentration of Si is 1E+18 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 24 nm. The temperature of the vapor deposition device is set to 950℃, the flow rate of TMIn is set to 800 ml / s, the third group of InGaN / GaN structures is grown, the doping concentration of In in the third group of InGaN / GaN structures is 5E+18 atom / cm 3 , the doping concentration of Si is 5E+17 atom / cm 3 , and the thickness of GaN in a single InGaN / GaN structure is 19.5 nm. The number of cycles of a single InGaN / GaN structure in the first group of InGaN / GaN structures, the second group of InGaN / GaN structures, and the third group of InGaN / GaN structures is 6, and the thickness of InGaN is 5 nm.

[0106] S8: growing a multi-quantum well active region layer on the stress release layer;

[0107] The temperature of the vapor deposition device is set to 950℃, the well / barrier temperature difference is set to 150℃, and H2 carrier gas is used. The well GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN is grown at a pressure of 190 Torr and a rotation speed of 500 rpm, and the barrier GaN / Al y1 Ga 1－y1 N is grown at a pressure of 400 Torr and a rotation speed of 700 rpm.

[0108] S9: growing a first electron blocking layer on the multi-quantum well active region layer;

[0109] The temperature of the vapor deposition device is set to 950 DEG C, the pressure is set to 200 Torr, the rotation speed is set to 600 rpm, H2 is used as the carrier gas, the V / III molar ratio is set to 200, and the thickness is set to 8 nm.

[0110] S10: growing a first p-GaN layer with a Mg doping concentration of 1.5*10 20 cm -3 -2 on the first electron blocking layer;

[0111] The temperature of the vapor deposition device is set to 800 DEG C, the pressure is set to 200 Torr, and the rotation speed is set to 600 rpm.

[0112] S11: growing a p-AlGaN layer with a thickness of 100 nm, a Mg doping concentration of 2*10 20 cm -3 -2, and an Al doping concentration of 1*10 21 cm -3 -2 on the first p-GaN layer;

[0113] The temperature of the vapor deposition device is set to 1000 DEG C, the pressure is set to 150 Torr, and the rotation speed is set to 1000 rpm.

[0114] S12: growing a second p-GaN layer with a Mg doping concentration of 1*10 20 cm -3 -2 on the p-AlGaN layer;

[0115] The temperature of the vapor deposition device is set to 1000 DEG C; then the pressure of the vapor deposition device is set to 600 Torr to grow a p-GaN layer with a thickness of 50 nm; and then the pressure of the vapor deposition device is set to 200 Torr to grow a p-GaN layer with a thickness of 50 nm.

[0116] Embodiment four of the present application is a GaN-based Micro LED epitaxial structure prepared by the preparation method of embodiment one.

[0117] Embodiment five of the present application is a GaN-based Micro LED epitaxial structure, which comprises, from bottom to top, an AlN substrate, an AlGaN / GaN buffer layer, a high-temperature undoped UGaN layer, a high-temperature doped NGaN layer, an n-AlGaN layer, a multi-period Si-doped NGaN layer, a stress release layer, a multi-quantum well active region layer, a first electron blocking layer, a first p-GaN layer, a p-AlGaN layer, and a second p-GaN layer.

[0118] The AlN substrate has a diameter of 8 inches, and the high-temperature undoped UGaN layer has a thickness of 1 mu m. The high-temperature doped NGaN layer has a thickness of 0.5 mu m and a Si doping concentration of 5*1018 cm -3 The thickness of the n-AlGaN layer is 10 nm, and the doping concentration of Al is 1E+17 atom / cm -3 The thickness of the multi-period Si-doped NGaN layer is 1.5 μm, and the period number is 80. The stress release layer is composed of a first group of InGaN / GaN structures, a second group of InGaN / GaN structures, and a third group of InGaN / GaN structures, which are stacked from top to bottom. In the first group of InGaN / GaN structures, the doping concentration of In is 1E+18 atom / cm 3 , and the doping concentration of Si is 1E+18 atom / cm 3 . The thickness of GaN in a single InGaN / GaN structure is 2 nm. In the second group of InGaN / GaN structures, the doping concentration of In is 5E+17 atom / cm 3 , and the doping concentration of Si is 5E+17 atom / cm 3 . The thickness of GaN in a single InGaN / GaN structure is 3.2 nm. In the third group of InGaN / GaN structures, the doping concentration of In is 1E+17 atom / cm 3 , and the doping concentration of Si is 5E+16 atom / cm 3 . The thickness of GaN in a single InGaN / GaN structure is 2.6 nm. The cycle number of a single InGaN / GaN structure in the first group of InGaN / GaN structures, the second group of InGaN / GaN structures, and the third group of InGaN / GaN structures is 3, and the thickness of InGaN is 1 nm. The well of the multi-quantum well active region layer is GaN / In x1 Ga 1－x1 N / In x2 Ga 1－x2 N / GaN, and the barrier is GaN / Al y1 Ga 1－y1 N. The thickness of the first electron blocking layer is 8 nm, and the Mg doping concentration of the first p-GaN layer is 5×10 19 cm -3 . The thickness of the p-AlGaN layer is 10 nm, the Mg doping concentration is 1×10 18 cm -3 , and the Al doping concentration is 1×10 19 cm -3 . The Mg doping concentration of the second p-GaN layer is 1×10 18 cm -3 . The second p-GaN layer includes a high-pressure grown p-GaN with a thickness of 10 nm and a low-pressure grown p-GaN with a thickness of 10 nm, which are arranged from bottom to top.

[0119] AsFigs. 1-3 Embodiment six of the present application is shown as follows: the vapor deposition device used in Embodiments one to three comprises, from top to bottom, a top cover 1, a graphite disc 2, a heat insulation plate 3 and a heating wire 4, the heating wire is connected to a rotating shaft 5 below, a through hole is arranged in the center of the top cover 1, the through hole is connected to a gas flow controller through a pipeline 6; the graphite disc 2 is provided with a placing groove 21 for placing a substrate with a diameter of 8 inches, the depth of the placing groove 21 is 2 mm, and a protruding structure (Tab) for fixing the substrate is arranged on the inner surface of the placing groove 21 at a position with a height of 110 um; the number of the through holes is two, one through hole is connected to N2 and / or H2 and / or NH3, and the other through hole is connected to a MO source; the distance between the top cover 1 and the graphite disc 2 is 27 cm.

[0120] Embodiment seven of the present application is shown as follows:

[0121] The difference between Embodiment seven and Embodiment six is only that the distance between the top cover 1 and the graphite disc 2 is 25 cm.

[0122] Embodiment eight of the present application is shown as follows:

[0123] The difference between Embodiment eight and Embodiment six is only that the distance between the top cover 1 and the graphite disc 2 is 30 cm.

[0124] Comparative Example one of the present application is shown as follows:

[0125] The difference between Comparative Example one and Embodiment one is only that:

[0126] S7: growing a superlattice InGaN / GaN stress release layer on the multi-period Si-doped NGaN layer, the temperature of the reaction chamber is 900℃, the pressure is 170 Torr, the rotating speed is 600 rpm, H2 carrier gas is used, the V / Ⅲ molar ratio is 3000, and the number of periods of the superlattice InGaN / GaN is 7, which can reduce dislocations and stress generated by the growth of the N layer.

[0127] S12: growing a second p-GaN layer on the p-AlGaN layer, the temperature of the reaction chamber is 1000℃, the pressure is 200 Torr, the rotating speed is 1000 rpm, 30 sccm of TMGa and 2500 sccm of Cp2Mg are introduced, the thickness of the second p-GaN layer is 30 nm, and the Mg doping concentration is 1×1019 cm-3. 19 cm -3 .

[0128] Comparative Example two of the present application is shown as follows:

[0129] The difference between Comparative Example two and Embodiment one is only that:

[0130] S7: growing a superlattice InGaN / GaN stress release layer on the multi-period Si-doped NGaN layer, the temperature of the reaction chamber is 900 DEG C, the pressure is 170 Torr, the rotation speed is 600 r / min, H2 is used as the carrier gas, the V / III molar ratio is 3000, the number of periods of the superlattice InGaN / GaN is 7, and the dislocations and stress generated by the growth of the N layer can be reduced.

[0131] The comparative example three of the present application is:

[0132] The difference between the comparative example three and the example one is only that:

[0133] S12: growing a second p-GaN layer on the p-AlGaN layer, the temperature of the reaction chamber is 1000 DEG C, the pressure is 200 Torr, the rotation speed is 1000 r / min, 30 sccm of TMGa and 2500 sccm of Cp2Mg are introduced, the thickness of the second p-GaN layer is 30 nm, and the Mg doping concentration is 1*10 19 cm -3 .

[0134] The epitaxial structures of the example one and the comparative examples one to three are respectively used to prepare LED chips (the specific steps are epitaxial wafer cleaning -> MESA -> CBL -> ITO -> MET -> PV -> electrical alloying -> COW testing -> grinding and thinning -> scribing -> sorting and full testing), the LED chips are made into 2*4 mil size LED particles, and performance testing is conducted on the LED particles, and the test results are shown in Table 1.

[0135] Table 1

[0136]

[0137] As shown in Table 1, the stress release layer and the second p-GaN layer structure can obviously improve the light efficiency and uniformity of the GaN-based Mini LED.

[0138] In summary, the GaN-based Micro LED epitaxial structure and the growth method and the vapor deposition device provided by the present application have the following advantages:

[0139] 1. The stress release layer, the multi-quantum well active region layer and the second P-GaN layer with specific structures are adopted. The stress release layer can form V-Pits with proper size centered on thread dislocation, can inhibit the non-radiation recombination of electron-hole pairs at defects, and improve the light emitting efficiency; the multi-quantum well active region layer can prevent the precipitation of In, improve the light emitting efficiency, reduce the accumulation of stress, enhance the stress release effect, greatly improve the warping phenomenon of the epitaxial wafer, make the In source in the growth process of the subsequent active layer uniformly distributed on the epitaxial wafer, and improve the wavelength consistency, light emitting intensity consistency and color consistency of the whole region of the LED including the central region in cooperation with the second P-GaN layer.

[0140] 2. The AlN substrate is treated by N2, H2 and NH3 simultaneously under the condition of low pressure and low speed, the surface of the AlN substrate is cleaned, and thinner and higher lattice quality AlN is obtained.

[0141] 3. The gas phase deposition device is improved, a shower-like structure is added in the center of the top cover, the chemical deposition in the central region V / III can be ensured, the uniformity of the chemical deposition is improved, and the growth of large-size epitaxial wafers is facilitated; the distance between the top cover and the graphite disc is reduced by 5-10 cm, the eddy current is reduced, the gas flow is more uniform, and the uniformity of the chemical deposition is improved.

[0142] The above only describes the embodiments of the present application, and does not limit the patent range of the present application, any equivalent transformation or direct or indirect application in the related technical field by using the content of the specification and drawings of the present application is also included in the patent protection range of the present application.

Claims

1. A GaN-based Micro LED epitaxial structure, characterized in that, The stress release layer comprises a first group of InGaN / GaN structures, a second group of InGaN / GaN structures and a third group of InGaN / GaN structures which are sequentially stacked from bottom to top; The doping concentration of In in the first group of InGaN / GaN structures is 1E+18~2E+20 atom / cm 3 The doping concentration of Si is 1E+18~2E+20 atom / cm 3 The thickness of GaN in a single InGaN / GaN structure is 2~15nm; The doping concentration of In in the second group of InGaN / GaN structures is 5E+17~1E+19 atom / cm 3 The doping concentration of Si is 5E+17~1E+18 atom / cm 3 The thickness of GaN in a single InGaN / GaN structure is 3.2~24nm; The doping concentration of In in the third group of InGaN / GaN structures is 1E+17~5E+18 atom / cm 3 The doping concentration of Si is 5E+16~5E+17 atom / cm 3 The thickness of GaN in a single InGaN / GaN structure is 2.6~19.5nm; The number of cycles of each InGaN / GaN structure in the first group, the second group and the third group is 3-6; The thickness of InGaN in each InGaN / GaN structure in the first group, the second group and the third group is 1-5 nm. 2.The growth method of the GaN-based Micro LED epitaxial structure of claim 1, wherein, The stress release layer is grown in a vapor deposition device, when growing the first group of InGaN / GaN structures, the temperature of the vapor deposition device is 800-850℃, and the flow rate of TMIn is 500-600 ml / s; when growing the second group of InGaN / GaN structures, the temperature of the vapor deposition device is 850-900℃, and the flow rate of TMIn is 600-700 ml / s; when growing the third group of InGaN / GaN structures, the temperature of the vapor deposition device is 900-950℃, and the flow rate of TMIn is 700-800 ml / s. 3.The GaN-based Micro LED epitaxial structure growth method of claim 2, wherein, The pressure of the vapor deposition device when growing the stress release layer is 150-200 Torr, and the V / III molar ratio is 1000-5000. 4.The GaN-based Micro LED epitaxial structure growth method of claim 2, wherein, An AlN substrate is placed in a vapor deposition device, the pressure of the vapor deposition device is set to 50-100 Torr, the rotation speed is set to 400-600 rpm, and N2, H2 and NH3 are introduced for 5-15 minutes; then an AlGaN / GaN buffer layer, a high-temperature undoped UGaN layer, a high-temperature doped NGaN layer, an n-AlGaN layer, a multi-period Si-doped NGaN layer, a stress release layer, a multi-quantum well active region layer, a first electron blocking layer, a first p-GaN layer, a p-AlGaN layer and a second p-GaN layer are sequentially grown on the AlN substrate. 5.The growth method of a GaN-based Micro LED epitaxial structure of claim 4, wherein, When growing the second p-GaN layer, the pressure of the vapor deposition device is first set to 400-600 Torr to grow a p-GaN layer with a thickness of 10-50 nm; then the pressure of the vapor deposition device is set to 100-200 Torr to grow a p-GaN layer with a thickness of 10-50 nm.

6. A vapor deposition apparatus for growing the GaN-based Micro LED epitaxial structure of claim 1, wherein, The top cover, the graphite disc, the heat insulation plate and the heating wire are sequentially arranged from top to bottom, a through hole is arranged at the center of the top cover, the through hole is connected to a gas flow controller through a pipeline, and a substrate with a diameter of 8 inches is placed in the graphite disc.

7. A vapour deposition apparatus as claimed in claim 6, characterised in that, The number of through holes is two, one of the through holes introduces N2 and / or H2 and / or NH3, and the other of the through holes introduces a MO source.

8. A vapour deposition apparatus as claimed in claim 6, characterised in that, The distance between the top cover and the graphite disc is 25-30 cm.

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