Micro-LED structure with double emergent directions and preparation method thereof

Abstract

The invention discloses a Micro-LED structure with double emergent directions and a preparation method of the Micro-LED structure. The Micro-LED structure comprises an N-type GaN layer, a mask layer, an N-type In < x > Ga < 1-x > N triangular island, a quantum well layer, a P-type layer, an electrode and other functional layers, wherein the upward crystal face of the N-type GaN layer is a non-polar face. According to the invention, an N-type InxGa1-xN triangular island with high symmetry is obtained by utilizing selective area epitaxy and combining lateral epitaxy, and LED epitaxial layers are grown on two symmetrical inclined planes of the triangular island, so that a Micro-LED structure with double emergent directions is formed and can be used as a basic display unit for near-eye naked eye three-dimensional display; meanwhile, mutually independent epitaxial LED structures are grown on the inclined planes of the triangular islands, so that adverse effects caused by etching damage of the traditional micromachining technology to the quantum wells and the P-type layers can be avoided, the edge effect of each light-emitting unit is effectively inhibited, and the light-emitting efficiency is improved; the light-emitting units are arranged on the basis of close packing, the area of the epitaxial wafer can be effectively utilized to the maximum extent, and economic benefits are maximized.

Description

Technical Field

[0001] The present invention relates to a Micro-LED structure with dual emission directions and a preparation method thereof, and belongs to the fields of semiconductor light-emitting devices, micro-LED displays, etc. Background Art

[0002] Micro-LED display technology has broad application prospects due to its advantages such as low energy consumption, long life and good color rendering, especially in the field of high-definition display of various sizes and shapes such as large displays, consumer electronics, car displays, virtual reality (VR), augmented reality (AR) and wearable displays. The current mainstream naked-eye three-dimensional (3D) technology uses a specific algorithm to arrange images interactively, and then achieves the naked-eye 3D effect through a parallax barrier set between the display backlight and the liquid crystal panel. However, there is a problem that the backlight module is blocked by the parallax barrier, which reduces the brightness and reduces the resolution of the screen. In the field of near-eye naked-eye 3D, due to the distance between the device and the observer and the area of ​​the light-emitting panel, the screen resolution seriously affects the display quality of the picture. Researchers have developed a variety of technologies to improve resolution, such as increasing pixel density through time multiplexing and using Micro-LED for small-scale high-resolution display. Among them, using Micro-LED to increase the screen PPI and achieve high-resolution near-eye 3D display is a popular research direction at present. Therefore, Micro-LED display technology has become one of the next-generation display technologies that relevant research institutions and enterprises around the world focus on. However, how to achieve 3D full-color display is one of the main challenges facing Micro-LED display technology. This is mainly because under existing technical conditions, it is still difficult to achieve monolithic integration of red, green and blue primary color Micro-LEDs.

[0003] At present, high-efficiency solid-state visible light sources are mainly GaN nitride-based blue-green LEDs and AlInGaP phosphide-based red LEDs. When the emission wavelength of AlInGaP-based materials is modulated from red light to yellow light, its band gap gradually transitions from a direct band gap to an indirect band gap, resulting in a rapid decrease in efficiency. This physical property severely restricts its development and application as a short-wavelength light source. In addition, AlInGaP-based LEDs have strong surface recombination, and the etching damage produced during the preparation of Micro-LEDs will further aggravate the surface recombination, leading to serious non-radiative recombination. Studies have shown that when the LED chip size is reduced to 262μm, its external quantum efficiency is less than 6%; when the size is further reduced to 32μm, the external quantum efficiency is less than 1%; there are even reports that 50×50μm 2The external quantum efficiency of a chip of this size is less than 0.12%. This phenomenon seriously restricts the application of AlInGaP-based LEDs as red light sources in the field of Micro-LED displays. The low luminous efficiency of InGaN-based LEDs in the long-wavelength band is due to the difficulty in epitaxial growth of InGaN with a high In component, but this problem can be solved through technical means, and certain progress has been made. On the other hand, the non-radiative recombination caused by etching damage in InGaN-based LEDs is relatively small, and its emission wavelength can cover the entire visible light band. Therefore, it is most likely to be used in fields such as Micro-LED displays and high-speed visible light communications, but the efficiency in the red light band is currently low. Therefore, solving the problems of epitaxial growth of InGaN films with a high In component and the non-radiative recombination caused by etching damage has become an important research topic. Summary of the invention

[0004] The main reason why Micro-LED is difficult to apply in near-eye naked-eye 3D display is that it is difficult to design a high-density Micro-LED dot matrix structure that can achieve 3D visual effects. In addition, quantum well etching damage is easily generated when preparing the Micro-LED structure, which leads to serious non-radiative recombination and reduces the light efficiency. The dual-emitting direction Micro-LED structure provided by the present invention is specially designed with densely packed In to solve the etching damage problem generated when preparing the Micro-LED structure. x Ga 1-x The N-triangle island structure further epitaxially grows independent Micro-LED structures, fundamentally avoiding damage to the multi-quantum wells by etching and improving the radiation recombination efficiency of the nitride Micro-LED; the light-emitting units are arranged based on dense stacking to maximize the use of the area of ​​the epitaxial wafer; at the same time, the unique Micro-LED structure with dual emission directions will emit light in two different directions when working. The structure can be further designed to allow light in two directions to enter the left and right eyes respectively, creating a parallax effect and achieving a 3D display effect; at the same time, this structure facilitates the design of 3D display algorithms, and thus achieves a delicate and realistic near-eye naked-eye 3D picture display, maximizing economic benefits.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a dual-emitting direction Micro-LED structure, which includes an N-type GaN layer 101 with a non-polar upward crystal plane, a mask layer 102 containing a microhole array, an N-type In with an In composition of 0≤x≤0.35, and a x Ga 1-x N triangle island 103, strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In with In composition y yGa 1-y N layer 107, and P type In y Ga 1-y The N layer 107 has a PL electrode 108 and a PR electrode 109 that have good ohmic contact, and an N electrode 1010 that has good ohmic contact with the N-type GaN layer 101 .

[0007] The N-type In x Ga 1-x The bottom of the N triangle island 103 is obtained by epitaxial growth upward from the microholes in the mask layer 102, and includes two left-right symmetrical triangular slopes and a triangular side surface perpendicular to the bottom surface. The strain control layer 104, the quantum well layer 105, the carrier control layer 106, the P-type In y Ga 1-y The N layer 107 and the PL electrode 108 (or the PR electrode 109) are both symmetrically arranged on the N-type In x Ga 1-x The parameters of the same structure are exactly the same; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PL electrode 108, the N-electrode 1010 and the left side x Ga 1-x The N triangle island slopes form the Micro-LED structure L; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PR electrode 109, the N-electrode 1010 and the right side x Ga 1-x The N triangular island slopes form the Micro-LED structure R. The N electrode 1010 can be located at the top or bottom of the GaN layer 101 with the upward crystal plane being a non-polar surface and establish a good ohmic contact. x Ga 1-x In front of the two inclined surfaces of the N triangle island, the N electrode 1010 and the N-type In x Ga 1-x The N triangle island 103 has no contact; when the N electrode 1010 is disposed at the bottom, the N electrode covers the entire bottom of the N-type GaN layer 101 whose upward crystal plane is a non-polar plane.

[0008] Preferably, the mask layer 102 containing the micropore array is a dielectric film of SiO2, SiN or hBN with a thickness of 5 to 50 nm prepared on the N-type GaN layer 101, and the micropore array is etched from top to bottom through process technology, and the underlying N-type GaN layer 101 is exposed in the micropores; the diameter of the micropores is between 0.5 and 5 μm, and the micropores are arranged in a densely packed form with the centers of the micropores. The distance between the center of any micropore and the centers of the six adjacent micropores is equal, and can be adjusted according to actual needs.

[0009] Preferably, the GaN layer 101 with a non-polar surface facing upward and the N-type In x Ga 1-x The upward crystal plane of the N triangle island 103 is also the (11-20) plane. At this time, the crystal planes of the left and right inclined planes are also one of the {1-101} or {1-102} crystal plane families. Since the crystal planes {1-101} or {1-102} are lower potential energy planes, a regular triangle island can be formed, and the layer structure above can grow regularly and controllably. In addition, the GaN layer 101 and the N-type In layer 103 with the upward crystal plane being the non-polar plane are x Ga 1-x The upward crystal plane of the N triangle island 103 can also be the (1-100) plane at the same time. In this case, the crystal planes of the left and right inclined planes are both {20-21} crystal plane family; x Ga 1-x The side surfaces of the N-triangular island 103 that are perpendicular to the bottom surface are all (000-1) surfaces. By arranging the light-emitting units based on dense packing, the area of ​​the epitaxial wafer can be effectively utilized to the greatest extent. Setting up a mesa structure fundamentally avoids the damage of etching to the multiple quantum wells, improves the radiation recombination efficiency of the nitride Micro-LED, and the mesa structure is conducive to releasing the underlying stress, improving the crystal quality of the entire structure of the LED, and thus weakening the effects of defects and polarization on carriers, thereby improving the luminous efficiency of the LED. At the same time, the unique dual-emitting direction Micro-LED structure will emit light in two different directions when working. The structure can be further designed to allow light in two directions to enter the left and right eyes respectively, producing a parallax effect and achieving a 3D display effect; at the same time, this structure facilitates the design of a 3D display algorithm, thereby achieving a delicate and realistic near-eye naked-eye 3D picture display, maximizing economic benefits.

[0010] Preferably, when the diameter of the micropores in the mask layer 102 is not greater than 1.5 μm, the N-type In x Ga 1-x The diameter of the circumscribed circle of the N-type triangular island 103 in the plane is adjusted between 5 and 20 μm as required, because when the micropores are small, it is easy to form regular islands, and the size of the islands can be controlled as required; when the diameter of the micropores in the mask layer 102 is greater than 1.5 μm, the N-type In x Ga 1-xThe in-plane circumferential diameter of the N triangular island 103 is 3 to 4 times the micropore diameter, but not exceeding 15 μm at most. When the micropores are large, the islands are prone to irregularity, so the size of the islands is limited.

[0011] Preferably, the strain control layer 104 covers the entire N-type In x Ga 1-x the two inclined planes of the N triangular island 103, but does not cover the N-type In x Ga 1-x the edge in the middle of the N triangular island 103; when the N-type In x Ga 1-x When the molar fraction x of the N triangular island is ≤ 0.05, the strain control layer 104 is a GaN / Al x1 Ga 1-x1 N / GaN composite layer from bottom to top with 1 to 3 periods, where Al x1 Ga 1-x1 the thickness of N is less than 3 nm, x1 < 0.15, that is, when x is small, the stress of In x Ga 1-x N is small, and only a lower component of AlGaN needs to be introduced to compensate for a certain in-plane stress in the c direction; when the N-type In x Ga 1-x When the molar fraction 0.05 < x < 0.15 of the N triangular island, the strain control layer 104 is a GaN / Al x1 Ga 1-x1 N / GaN / In x Ga 1-x N composite layer, where In x Ga 1-x the molar fraction x of N is the molar fraction of the N-type In x Ga 1-x triangular island, and control the thickness of Al x1 Ga 1-x1 N to be less than 2 nm; where the lattice mismatch value of GaN and Al x1 Ga 1-x1 N in the c direction is △1 = -0.03915 × x1; In x Ga 1-x the lattice mismatch value of N and GaN in the c direction is △2 = 0.09797 × x; by adjusting the molar fractions x and x1, the lattice mismatch values of Al x1 Ga 1-x1 N and In x Ga 1-x N in the c direction with GaN are made equivalent, that is, x1 = 2.5 × x ± 0.05 is satisfied, so as to achieve stress compensation between layers, and then obtain a high-quality quantum well and improve the overall Micro-LED light efficiency.

[0012] Preferably, the left and right groups of quantum wells are symmetrically covered on the top of the strain control layer 104, have the same area and are not connected to each other, and their shape is consistent with the inclined surface of the GaN three-dimensional triangular island 103; when the quantum wells emit red, green, and blue light, respectively, the number of quantum well pairs is 1 to 2 pairs, 2 to 4 pairs, and 3 to 5 pairs, respectively; the layer structure of the quantum well is In x2 Ga 1-x2 N / GaN / Al x3 Ga 1-x3 N / GaN, due to In x2 Ga 1-x2 The lattice mismatch between N and GaN in the c direction is △3 = 0.09797 × x2; Al x3 Ga 1-x3 The lattice mismatch value between N and GaN in the c direction is △4 = -0.03915 × x3; by adjusting the molar composition x2 and x3, In x2 Ga 1-x2 N and Al x3 Ga 1-x3 The lattice mismatch value of N in the c direction is equivalent to that of GaN, that is, x3 = 2.5 × x2 ± 0.05, while controlling In x2 Ga 1-x2 The thickness of N is 2 to 4 nm, and the two layers of GaN and Al x3 Ga 1-x3 The total thickness of N does not exceed 6nm, which can better release stress, improve the radiation recombination efficiency of the quantum well, and improve the light efficiency.

[0013] Preferably, the carrier regulation layer 106 is one of an electron blocking layer and a hole injection layer; wherein the electron blocking layer is an Al2O3 layer having 2 to 8 cycles and a single cycle thickness of less than 8 nm. y1 Ga (1-y1) N / GaN superlattice, where the molar composition y1 is between 0.1 and 0.6, and Al y1 Ga (1-y1) The hole injection layer is P-doped with an overall thickness of less than 30nm Al y2 Ga (1-y2) N / In y3 Ga (1-y3) N / GaN superlattice, Mg doping concentration is 5×10 17 cm -3 ~1×10 19 cm -3 The hole concentration is not higher than 1×10 18 cm -3By setting an electron blocking layer with a wider bandgap or a highly P-doped hole injection layer, the carriers in the active region, i.e., the multiple quantum wells, are restricted, thereby increasing the overlap of the hole and electron wave functions in the multiple quantum wells and achieving a higher radiation recombination efficiency.

[0014] Preferably, P-type In y Ga 1-y The thickness of the N layer 107 is between 50 and 200 nm, and the molar composition y is between 0 and 0.15. When y=0, it is GaN. The Mg element doping concentration is 2×10 19 cm -3 ~5×10 19 cm -3 The hole concentration is not less than 1×10 18 cm -3 ; Among them, P type In y Ga 1-y In the 5-30 nm thickness region on the upper surface of the N layer 107, the doping concentration of the Mg element is not less than 1×10 20 cm -3 , the hole concentration is not less than 5×10 18 cm -3 .

[0015] On the other hand, the present invention provides a method for preparing the Micro-LED structure with dual emission directions.

[0016] The method for preparing a dual-emitting direction Micro-LED structure can be used to prepare a structure including an N-type GaN layer 101 with a non-polar upward crystal plane, a mask layer 102 containing a microhole array, an N-type In with an In component of 0≤x≤0.35, which are sequentially arranged from bottom to top. x Ga 1-x N triangle island 103, strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In with In composition y y Ga 1-y N layer 107, and P type In y Ga 1-y The N-type GaN layer 107 has a PL electrode 108 and a PR electrode 109 that have good ohmic contact, and an N-type GaN layer 1010 that has good ohmic contact. x Ga 1-x The bottom of the N triangle island 103 is obtained by epitaxial growth upward from the microholes in the mask layer 102, and includes two left-right symmetrical triangular slopes and a triangular side surface perpendicular to the bottom surface. In addition, the strain control layer 104, the quantum well layer 105, the carrier control layer 106, the P-type In y Ga 1-yThe N layer 107 and the PL electrode 108 (or the PR electrode 109) are both symmetrically arranged on the N-type In x Ga 1-x The parameters of the same structure are exactly the same; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PL electrode 108, the N-electrode 1010 and the left side x Ga 1-x The N triangle island slope forms the Micro-LED structure L; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type InyGa1-yN layer 107, PR electrode 109, N electrode 1010 and the N-type In x Ga 1-x The N triangular island slope forms the Micro-LED structure R. The N electrode 1010 is disposed on the top of the N-type GaN layer 101 whose upward crystal surface is a non-polar surface. x Ga 1-x In front of the two inclined surfaces of the N triangle island, the N electrode 1010 and the N-type In x Ga 1-x The N triangle island 103 has no contact. The preparation method of the Micro-LED structure includes the following steps: a) preparing a non-polar N-type GaN template as the N-type GaN layer 101 with the upward crystal plane being the non-polar plane, or epitaxially growing a layer of N-type GaN film with the upward crystal plane being the non-polar plane on a sapphire, Si or SiC substrate as the N-type GaN layer 101; b) preparing a non-metallic compound dielectric layer on the N-type GaN layer 101 whose upward crystal surface is a non-polar surface, and using micro-machining technology to process a micro-hole structure on the dielectric layer to form a mask layer 102 containing a micro-hole array, exposing the N-type GaN layer 101 below; c) using the selective epitaxial growth technology to perform selective epitaxy using the micropores, and then controlling the temperature of the epitaxial growth, V / III ratio, reaction chamber pressure, carrier gas and reactant source flow rate to achieve lateral epitaxy, forming an In component of 0≤x≤ 0.35 N-type In x Ga 1-x N Delta Island 103; d) In N-type In x Ga 1-x The strain control layer 104 is epitaxially grown on the basis of the N-type triangular island 103, and combined with micro-machining technology, the strain control layer 104 covers the entire N-type In x Ga 1-xN triangle island 103 left and right two slopes, but not covered by N type In x Ga 1- x At the edge in the middle of N triangle island 103; e) epitaxially growing a quantum well layer 105 on the strain control layer 104 so that the quantum well symmetrically covers the top of the strain control layer 104; f) epitaxially growing a carrier regulation layer 106 on the quantum well layer 105 and covering the quantum well layer 105; g) epitaxially growing P-type In on the carrier regulation layer 106 y Ga 1-y N layer 107, covering the carrier regulation layer 106; h) Using standard micromachining technology, the corresponding position of the N electrode 1010 on the mask layer 102 is etched to expose the underlying N-type GaN layer 101; one of the evaporation coating and magnetron sputtering techniques is used to complete the PL electrode 108, the PR electrode 109 and the N electrode 1010 to complete the preparation of this Micro-LED structure.

[0017] The method for preparing a dual-emitting direction Micro-LED structure can be used to prepare a structure including an N-type GaN layer 101 with a non-polar upward crystal plane, a mask layer 102 containing a microhole array, an N-type In with an In component of 0≤x≤0.35, which are sequentially arranged from bottom to top. x Ga 1-x N triangle island 103, strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In with In composition y y Ga 1-y N layer 107, and P type In y Ga 1-y The N-type GaN layer 107 has a PL electrode 108 and a PR electrode 109 that have good ohmic contact, and an N-type GaN layer 1010 that has good ohmic contact. x Ga 1-x The bottom of the N triangle island 103 is obtained by epitaxial growth upward from the microholes in the mask layer 102, and includes two left-right symmetrical triangular slopes and a triangular side surface perpendicular to the bottom surface. In addition, the strain control layer 104, the quantum well layer 105, the carrier control layer 106, the P-type In y Ga 1-y The N layer 107 and the PL electrode 108 (or the PR electrode 109) are both symmetrically arranged on the N-type In x Ga 1-xThe parameters of the same structure are exactly the same; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PL electrode 108, the N-electrode 1010 and the left side x Ga 1-x The N triangle island slopes form the Micro-LED structure L; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PR electrode 109, the N-electrode 1010 and the right side x Ga 1-x The N triangular island slopes form a Micro-LED structure R. The N electrode 1010 is disposed at the bottom of the GaN layer 101 whose upward crystal surface is a non-polar surface, directly covering the bottom of the entire N-type GaN layer 101. The preparation method of this Micro-LED structure includes the following steps: a) preparing a non-polar N-type GaN template as the N-type GaN layer 101 with the upward crystal plane being the non-polar plane, or epitaxially growing a layer of N-type GaN film with the upward crystal plane being the non-polar plane on a sapphire, Si or SiC substrate as the N-type GaN layer 101; b) preparing a non-metallic compound dielectric layer on the N-type GaN layer 101 whose upward crystal surface is a non-polar surface, and using micro-machining technology to process a micro-hole structure on the dielectric layer to form a mask layer 102 containing a micro-hole array, exposing the N-type GaN layer 101 below; c) using the selective epitaxial growth technology to perform selective epitaxy using the micropores, and then controlling the temperature of the epitaxial growth, V / III ratio, reaction chamber pressure, carrier gas and reactant source flow rate to achieve lateral epitaxy, forming an In component of 0≤x≤ 0.35 N-type In x Ga 1-x N Delta Island 103; d) In N-type In x Ga 1-x The strain control layer 104 is epitaxially grown on the basis of the N-type triangular island 103, and combined with micro-machining technology, the strain control layer 104 covers the entire N-type In x Ga 1-x N triangle island 103 left and right two slopes, but not covered by N type In x Ga 1- x At the edge in the middle of N triangle island 103; e) epitaxially growing a quantum well layer 105 on the strain control layer 104 so that the quantum well symmetrically covers the top of the strain control layer 104; f) epitaxially growing a carrier regulation layer 106 on the quantum well layer 105 and covering the quantum well layer 105; g) epitaxially growing P-type In on the carrier regulation layer 106 y Ga 1-y N layer 107, covering the carrier regulation layer 106; h) using one of the evaporation coating and magnetron sputtering techniques to prepare the PL electrode 108 and the PR electrode 109; i) The structure above the N-type GaN layer 101 is peeled off using a peeling process, and an N-electrode 1010 is prepared at the original bottom of the N-type GaN layer 101 using a technique selected from evaporation coating and magnetron sputtering to complete the preparation of the Micro-LED structure.

[0018] Beneficial effects:

[0019] The present invention proposes a dual-emitting direction Micro-LED structure and a preparation method thereof. The design adopts micropore selective epitaxy technology to grow N-type In with a lower potential energy surface. x Ga 1-x N, naturally forms a triangular island structure with high symmetry, thereby achieving regular and controllable growth of the island surface layer structure. x Ga 1-x The independent Micro-LED full structure is prepared on the inclined surface of the N triangle island, which fundamentally avoids the damage of etching to the multi-quantum well, thereby improving the radiation recombination efficiency of the nitride Micro-LED. In addition, the triangular island structure helps to release the stress between layers during epitaxial growth, improves the crystal quality of the prepared Micro-LED full structure, weakens the influence of defects and polarization on carriers, and improves the luminous efficiency of Micro-LED.

[0020] At the same time, to alleviate In x Ga 1-x The N quantum well has a series of adverse effects (such as defects caused by stress release) caused by the large lattice mismatch with GaN. The present invention sets a strain control layer and a specially designed quantum well structure before growing the quantum well, and introduces an AlGaN layer with a specific molar composition to produce a strain opposite to that of InGaN to offset the strain of InGaN. The principle is as follows: First, according to the formula

[0021] Calculate the lattice mismatch value, where △ is the lattice mismatch value, c GaN The c-axis lattice constant of GaN is 5.185 angstroms, c n Alx1 Ga 1-x1 N and In x Ga 1-x The c-axis lattice constant of N. n The calculation formula is: c n =b×c AlN或InN +(1-b)c GaN

[0022] Where b is x, x1, x2 or x3, c AlN或InN is the c-axis lattice constant of AlN or InN, which are 4.982 angstroms and 5.693 angstroms respectively. Substituting the corresponding values ​​into Al x1 Ga 1-x1 The lattice mismatch value between N and GaN in the c direction is △1 = -0.03915×x1; In x Ga 1-x The lattice mismatch between N and GaN in the c direction is △2 = 0.09797 × x; In x2 Ga 1-x2 The lattice mismatch between N and GaN in the c direction is △3 = 0.09797 × x2; Al x3 Ga 1-x3 The lattice mismatch value between N and GaN in the c direction is △4 = -0.03915×x3. By adjusting the molar composition x, x1, x2, x3, Al x1 Ga 1-x1 N and In x Ga 1-x The lattice mismatch between N and GaN in the c direction is comparable. x2 Ga 1-x2 N and Al x3 Ga 1-x3 The lattice mismatch value of N in the c direction is equivalent to that of GaN (such as △1=-△2, △3=-△4), that is, x1=2.5×x±0.05, x3=2.5×x2±0.05. At this time, AlGaN will produce a strain in the opposite direction and with a similar value to InGaN to offset the strain of InGaN and suppress defects in InGaN due to excessive strain, thereby obtaining high-quality quantum wells and improving the overall Micro-LED lighting efficiency.

[0023] An electron blocking layer or a highly P-doped hole injection layer with a wider bandgap width is set to limit the carriers in the active area, namely the multiple quantum wells, so that the overlap of the hole and electron wave functions in the multiple quantum wells is increased, and a higher radiation recombination efficiency is achieved, further solving the problem of the decrease in internal quantum efficiency as the injection current density increases.

[0024] At the same time, the present invention uses dense packing as the basis to arrange the light-emitting units, which effectively utilizes the area of ​​the epitaxial wafer to the greatest extent. The naturally formed highly symmetrical Micro-LED structure with dual emission directions will emit light in two different directions when working. The structure can be further designed to allow the light in the two directions to enter the left and right eyes respectively, producing a parallax effect and achieving a 3D display effect; at the same time, this structure facilitates the design of 3D display algorithms, and has great advantages in the field of near-eye naked-eye 3D display. At the same time, relying on the micron-level size of Micro-LED, a higher PPI per unit area can be achieved, and a delicate and realistic picture can be easily achieved, which has a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Exemplary embodiments are shown in the referenced drawings. The embodiments and drawings disclosed herein are to be considered illustrative rather than restrictive.

[0026] Figure 1 A cross-sectional schematic diagram of a Micro-LED structure with dual emission directions when an N-electrode provided by the present invention is placed on top of an N-type GaN layer whose upward crystal plane is a non-polar plane.

[0027] Figure 2 A schematic top view of a Micro-LED structure with dual emission directions when an N-electrode provided by the present invention is placed on top of an N-type GaN layer whose upward crystal plane is a non-polar plane.

[0028] Figure 3 A cross-sectional schematic diagram of a Micro-LED structure with dual emission directions when an N-electrode provided by the present invention is placed at the bottom of an N-type GaN layer whose upward crystal plane is a non-polar plane.

[0029] Figure 4 A schematic top view of a Micro-LED structure with dual emission directions when an N-electrode provided by the present invention is placed at the bottom of an N-type GaN layer whose upward crystal plane is a non-polar plane.

[0030] In the figure: 101 is an N-type GaN layer with a non-polar surface facing upward, 102 is a mask layer containing a microhole array, and 103 is an N-type In x Ga 1-x N triangle island, 104 is a strain control layer, 105 is a quantum well layer, 106 is a carrier control layer, 107 is a P-type In y Ga 1-y N layer, 108 is a PL electrode, 109 is a PR electrode, and 1010 is an N electrode. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0033] Embodiment 1:

[0034] The cross-sectional schematic diagram of Example 1 is as follows Figure 1 , the top view diagram is as follows Figure 2 , including an N-type GaN layer 101 with a non-polar surface facing upward, a mask layer 102 containing a microhole array, an N-type In x Ga 1-x N triangle island 103, strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y N layer 107, and P type In y Ga 1-y The N-type GaN layer 107 has a PL electrode 108 and a PR electrode 109 that have good ohmic contact, and an N-type GaN layer 1010 that has good ohmic contact. x Ga 1-x The bottom of the N triangle island 103 is obtained by epitaxial growth upward from the microholes in the mask layer 102, and includes two left-right symmetrical triangular slopes and a triangular side surface perpendicular to the bottom surface. In addition, the strain control layer 104, the quantum well layer 105, the carrier control layer 106, the P-type In y Ga 1-y The N layer 107 and the PL electrode 108 (or the PR electrode 109) are both symmetrically arranged on the N-type In x Ga 1-x The parameters of the same structure are exactly the same; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PL electrode 108, the N-electrode 1010 and the left side x Ga1-x The N triangle island slopes form the Micro-LED structure L; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PR electrode 109, the N-electrode 1010 and the right side x Ga 1-x The N triangular island slope forms the Micro-LED structure R. The N electrode 1010 is disposed on the top of the N-type GaN layer 101 whose upward crystal surface is a non-polar surface. x Ga 1- x In front of the two inclined surfaces of the N triangle island, the N electrode 1010 and the N-type In x Ga 1-x N triangle island 103 no contact.

[0035] The specific parameters and preparation method of Example 1 are as follows:

[0036] An N-type GaN template with a non-polar (11-20) upward crystal plane is used as the N-type GaN layer 101. A 25 nm thick SiO2 layer is covered on the N-type GaN layer 101 as a non-metallic compound dielectric layer; a micropore array is arranged in the non-metallic compound dielectric layer, and the N-type GaN layer 101 of the lower layer is exposed in the micropores; wherein the diameter of the micropores is 1.5 μm, and the micropores are arranged in a densely packed form with the center of the micropores, and the distance between the center of any micropore and the center of the adjacent 6 micropores is 25 μm.

[0037] N-type In with In composition x=0.05 is formed at the above micropore position. x Ga 1-x N triangle island 103; N type In x Ga 1-x The diameter of the circumscribed circle of the N-type triangular island 103 in the plane is 15 μm. The GaN layer 101 and the N-type In x Ga 1-x The upward crystal plane of the N triangle island 103 is also the (11-20) plane. At this time, the crystal planes of the left and right inclined planes are also {1-101} crystal plane family. x Ga 1-x The side surface of the N-triangle island 103 that is perpendicular to the bottom surface is the (000-1) plane.

[0038] In N-type x Ga 1-x Two cycles of bottom-up GaN / Al are arranged on the symmetric slope of the N triangle island 103. x1 Ga 1-x1 N / GaN composite layer, in which Al x1 Ga 1-x1The thickness of N is 2.5 nm, x1=0.1, and AlGaN with a lower composition is introduced to compensate for a certain in-plane stress in the c direction, serving as the strain control layer 104. The strain control layer 104 covers the entire N-type In x Ga 1-x N triangle island 103 left and right two slopes, but not covered by N type In x Ga 1-x The edge in the middle of N triangle island 103.

[0039] Two groups of left and right quantum wells are symmetrically covered on the top of the strain control layer 104, with the same area and no connection, and their shapes are consistent with the inclined surface of the GaN three-dimensional triangular island 103; when the wavelengths of the quantum wells are red, green, and blue, the number of quantum well pairs is 2, 3, and 4, respectively; the layer structure of the quantum well is In x2 Ga 1-x2 N / GaN / Al x3 Ga 1-x3 N / GaN, where x2=0.2, x3=0.5 and In x2 Ga 1-x2 The thickness of N is 3nm, two layers of GaN and Al x3 Ga 1-x3 The total thickness of N is 5 nm.

[0040] Six periods of Al2O3 with a thickness of 8 nm per period are arranged on the quantum well layer 105. y1 Ga (1-y1) N / GaN superlattice, where the molar composition y1 is 0.4, acts as a carrier regulation layer.

[0041] A P-type In layer with a thickness of 100 nm and a molar composition y of 0.1 is set on the carrier control layer. y Ga 1-y N layer 107; the Mg doping concentration is adjusted to 3×10 19 cm -3 , and its hole concentration is 1.5×10 18 cm -3 ; Among them, P type In y Ga 1-y The doping concentration of Mg element in the 20 nm thickness region on the upper surface of the N layer 107 is 1.5×10 20 cm -3 , and its hole concentration is 5×10 18 cm -3 .

[0042] The specific preparation process of this example structure is as follows: a) preparing an N-type GaN template with an upward crystal plane being a non-polar plane (11-20) as the N-type GaN layer 101; b) preparing a non-metallic compound dielectric layer on the N-type GaN layer 101, and using micro-machining technology to process a micro-hole structure on the dielectric layer to form a mask layer 102 containing a micro-hole array, exposing the N-type GaN layer 101 below; c) using the selective epitaxial growth technology to perform selective epitaxy using the micropores, and then controlling the temperature of the epitaxial growth, V / III ratio, reaction chamber pressure, carrier gas and reactant source flow rate to achieve lateral epitaxy, forming an In component of x = 0.05 N-type In x Ga 1-x N Delta Island 103; d) In N-type In x Ga 1-x The strain control layer 104 is epitaxially grown on the basis of the N-type triangular island 103, and combined with micro-machining technology, the strain control layer 104 covers the entire N-type In x Ga 1-x N triangle island 103 left and right two slopes, but not covered by N type In x Ga 1- x At the edge in the middle of N triangle island 103; e) epitaxially growing a quantum well layer 105 on the strain control layer 104 so that the quantum well symmetrically covers the top of the strain control layer 104; f) epitaxially growing a carrier regulation layer 106 on the quantum well layer 105 and covering the quantum well layer 105; g) epitaxially growing P-type In on the carrier regulation layer 106 y Ga 1-y N layer 107, covering the carrier regulation layer 106; h) Using standard micromachining technology, the corresponding position of the N electrode 1010 on the mask layer 102 is etched to expose the underlying N-type GaN layer 101; one of the evaporation coating and magnetron sputtering techniques is used to complete the PL electrode 108, the PR electrode 109 and the N electrode 1010 to complete the preparation of this Micro-LED structure.

[0043] Embodiment 2:

[0044] The cross-sectional schematic diagram of Example 2 is as follows Figure 3 , the top view diagram is as follows Figure 4 , including an N-type GaN layer 101 with a non-polar surface facing upward, a mask layer 102 containing a microhole array, an N-type In x Ga 1-x N triangle island 103, strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In with In composition yy Ga 1-y N layer 107, and P type In y Ga 1- y The N-type GaN layer 107 has a PL electrode 108 and a PR electrode 109 that have good ohmic contact, and an N-type GaN layer 1010 that has good ohmic contact. x Ga 1-x The bottom of the N triangle island 103 is obtained by epitaxial growth upward from the microholes in the mask layer 102, and includes two left-right symmetrical triangular slopes and a triangular side surface perpendicular to the bottom surface. In addition, the strain control layer 104, the quantum well layer 105, the carrier control layer 106, the P-type In y Ga 1-y The N layer 107 and the PL electrode 108 (or the PR electrode 109) are both symmetrically arranged on the N-type In x Ga 1-x The parameters of the same structure are exactly the same; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PL electrode 108, the N-electrode 1010 and the left side x Ga 1-x The N triangle island slopes form the Micro-LED structure L; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PR electrode 109, the N-electrode 1010 and the right side x Ga 1-x The N triangular island slopes form a Micro-LED structure R. The N electrode 1010 is disposed at the bottom of the GaN layer 101 whose upward crystal surface is a non-polar surface, directly covering the bottom of the entire N-type GaN layer 101 .

[0045] The specific parameters and preparation method of Example 2 are as follows:

[0046] An N-type GaN film grown on a sapphire substrate with a non-polar (11-20) upward crystal plane is used as the N-type GaN layer 101. A 15 nm thick hBN layer is provided on the N-type GaN layer 101 as a non-metallic compound dielectric layer; a micropore array is provided in the non-metallic compound dielectric layer, and the N-type GaN layer 101 of the lower layer is exposed in the micropores; wherein the diameter of the micropores is 2 μm, and the micropores are arranged in a densely packed form with the center of the micropores, and the distance between the center of any micropore and the center of the adjacent 6 micropores is 20 μm.

[0047] An N-type In with an In composition of x=0.15 is formed at the center of the micropore. x Ga 1-x N triangle island 103; N type In x Ga 1- x The diameter of the circumscribed circle of the N triangle island 103 in the plane is 10 μm. The GaN layer 101 on the non-polar surface and the N-type In x Ga 1-x The upward crystal plane of the N triangle island 103 is also the (11-20) plane. At this time, the crystal planes of the left and right inclined planes are also {1-102} crystal plane family. x Ga 1-x The side surfaces of the N-triangle island 103 that are perpendicular to the bottom surface are all (000-1) planes.

[0048] In N-type x Ga 1-x The symmetric slope of the N triangle island 103 is provided with 3 cycles of bottom-up GaN / Al x1 Ga 1-x1 N / GaN / In x Ga 1-x N composite layer, where In x Ga 1-x The molar component x of N is N-type In x Ga 1-x Molar composition of N triangle island, Al x1 Ga 1-x1 The thickness of N is 1.5 nm, x=0.16, x1=0.4, and serves as the strain control layer 104. The strain control layer 104 covers the entire N-type In x Ga 1-x N triangle island 103 left and right two slopes, but not covered by N type In x Ga 1-x The edge in the middle of N triangle island 103.

[0049] Two groups of left and right quantum wells are symmetrically covered on the top of the strain control layer 104, with the same area and no connection, and their shapes are consistent with the inclined surface of the GaN three-dimensional triangular island 103; when the wavelengths of the quantum wells are red, green, and blue, the number of quantum well pairs is 1 pair, 4 pairs, and 3 pairs respectively; the layer structure of the quantum well is In x2 Ga 1-x2 N / GaN / Al x3 Ga 1-x3 N / GaN, where x2=0.18, x3=0.45 and In x2 Ga 1-x2 The thickness of N is 2nm, two layers of GaN and Al x3 Ga 1-x3The total thickness of N does not exceed 6 nm.

[0050] A 25 nm thick Al y2 Ga (1-y2) N / In y3 Ga (1-y3) N / GaN superlattice, doped, so that the Mg element doping concentration is 5×10 18 cm -3 , and its hole concentration is 7×10 17 cm -3 Acts as a carrier regulation layer.

[0051] A P-doped Al layer with a total thickness of less than 30 nm is set on the carrier regulation layer. y2 Ga (1-y2) N / In y3 Ga (1-y3) N / GaN superlattice, and the Mg doping concentration of the carrier control layer is controlled to 6×10 18 cm -3 , with a hole concentration of 1×10 18 cm -3 Acts as a carrier regulation layer.

[0052] A P-type In layer with a thickness of 90 nm and a molar composition y of 0.08 is set on the carrier regulation layer. y Ga 1-y N layer 107; the Mg doping concentration is adjusted to 3×10 19 cm -3 , and its hole concentration is 2×10 18 cm -3 ; Among them, P type In y Ga 1-y In the 25 nm thick region on the upper surface of the N layer 107, the doping concentration of Mg element is 2×10 20 cm -3 , and its hole concentration is 6×10 18 cm -3 .

[0053] The specific preparation process of this example structure is as follows: a) epitaxially growing a layer of N-type GaN thin film with a non-polar (11-20) upward crystal plane on a sapphire substrate as the N-type GaN layer 101; b) preparing a non-metallic compound dielectric layer on the N-type GaN layer 101, and using micro-machining technology to process a micro-hole structure on the dielectric layer to form a mask layer 102 containing a micro-hole array, exposing the N-type GaN layer 101 below; c) using the selective epitaxial growth technology to perform selective epitaxy using the micropores, and then controlling the temperature of the epitaxial growth, The V / III ratio, the reaction chamber pressure, the carrier gas, and the flow rate of the reactant source are used to achieve lateral epitaxy to form an In component of N-type In with x=0.15 x Ga 1-x N Delta Island 103; d) In N-type In x Ga 1-x The strain control layer 104 is epitaxially grown on the basis of the N-type triangular island 103, and combined with micro-machining technology, the strain control layer 104 covers the entire N-type In x Ga 1-x N triangle island 103 left and right two slopes, but not covered by N type In x Ga 1-x At the edge in the middle of N triangle island 103; e) epitaxially growing a quantum well layer 105 on the strain control layer 104 so that the quantum well symmetrically covers the top of the strain control layer 104; f) epitaxially growing a carrier regulation layer 106 on the quantum well layer 105 and covering the quantum well layer 105; g) epitaxially growing P-type In on the carrier regulation layer 106 y Ga 1-y N layer 107, covering the carrier regulation layer 106; h) using a technique selected from evaporation coating and magnetron sputtering to prepare the PL electrode 108 and the PR electrode 109; i) The structure above the N-type GaN layer 101 is peeled off using a peeling process, and an N-electrode 1010 is prepared at the original bottom of the N-type GaN layer 101 using a technique selected from evaporation coating and magnetron sputtering to complete the preparation of the Micro-LED structure.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A Micro-LED structure with dual emission directions, characterized in that: The N-type GaN layer 101 with a non-polar surface facing upward, the mask layer 102 containing a microhole array, and the N-type In layer 103 with an In composition of 0≤x≤0.35 are sequentially arranged from bottom to top. x Ga 1-x N triangle island 103, strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In with In composition y y Ga 1-y N layer 107, and P type In y Ga 1-y The N-type GaN layer 107 has a PL electrode 108 and a PR electrode 109 that have good ohmic contact, and an N-type GaN layer 1010 that has good ohmic contact. x Ga 1-x The bottom of the N triangle island 103 is obtained by epitaxial growth upward from the microholes in the mask layer 102, and includes two left-right symmetrical triangular slopes and a triangular side surface perpendicular to the bottom surface. In addition, the strain control layer 104, the quantum well layer 105, the carrier control layer 106, the P-type In y Ga 1-y The N layer 107 and the PL electrode 108 (or the PR electrode 109) are both symmetrically arranged on the N-type In x Ga 1-x The parameters of the same structure are exactly the same; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PL electrode 108, the N-electrode 1010 and the left side x Ga 1-x The N triangle island slopes form the Micro-LED structure L; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PR electrode 109, the N-electrode 1010 and the right side x Ga 1-x The N triangular island slopes form the Micro-LED structure R. The N electrode 1010 can be located at the top or bottom of the GaN layer 101 with the upward crystal plane being a non-polar surface and establish a good ohmic contact. x Ga 1-x In front of the two inclined surfaces of the N triangle island, the N electrode 1010 and the N-type In x Ga 1-x The N triangle island 103 has no contact; when the N electrode 1010 is disposed at the bottom, the N electrode covers the entire bottom of the N-type GaN layer 101 whose upward crystal plane is a non-polar plane.

2. The dual-emitting direction Micro-LED structure according to claim 1, characterized in that: The mask layer 102 containing the micropore array is a dielectric film of SiO2, SiN or hBN with a thickness of 5 to 50 nm prepared on the N-type GaN layer 101, and the micropore array is etched from top to bottom through process technology, and the underlying N-type GaN layer 101 is exposed in the micropores; the diameter of the micropores is between 0.5 and 5 μm, and the micropores are arranged in a densely packed form with the center of the micropores. The distance between the center of any micropore and the center of the adjacent 6 micropores is equal, and can be adjusted according to actual needs.

3. The dual-emitting direction Micro-LED structure according to claim 1, characterized in that: The N-type GaN layer 101 with a non-polar upward crystal surface and the N-type In x Ga 1-x The upward crystal plane of the N triangle island 103 is the (11-20) plane, and the crystal planes of the left and right inclined planes are one of the {1-101} or {1-102} crystal plane families. In addition, the N-type GaN layer 101 and the N-type In x Ga 1- x The upward crystal plane of the N triangle island 103 can also be the (1-100) plane at the same time. In this case, the crystal planes of the left and right inclined planes are both {20-21} crystal plane family; x Ga 1-x The side of the N triangle island 103 perpendicular to the bottom surface is the (000-1) plane; when the diameter of the micropores in the mask layer 102 is not greater than 1.5 μm, the N-type In x Ga 1-x The diameter of the circumscribed circle of the N triangle island 103 in the plane is between 5 and 20 μm, which can be adjusted as needed; when the diameter of the micropores in the mask layer 102 is greater than 1.5 μm, the N-type In x Ga 1-x The diameter of the circumscribed circle of the N triangular island 103 within the plane is 3 to 4 times the diameter of the micropore, but the maximum does not exceed 15 μm.

4. The dual-emitting direction Micro-LED structure according to claim 1, characterized in that: The strain control layer 104 covers the left and right inclined planes of the N-type In x Ga 1-x N triangular island 103, but does not cover the edge at the middle of the N-type In x Ga 1-x N triangular island 103; when the molar fraction x of the N-type In x Ga 1-x N triangular island is x ≤ 0.05, the strain control layer 104 is a 1 - 3 cycle GaN / Al x1 Ga 1-x1 N / GaN composite layer from bottom to top, where the thickness of Al x1 Ga 1-x1 N is less than 3 nm, x1 < 0.15; when the molar fraction of the N-type In x Ga 1-x N triangular island is 0.05 < x < 0.15, the strain control layer 104 is a 1 - 3 cycle GaN / Al x1 Ga 1-x1 N / GaN / In x Ga 1-x N composite layer from bottom to top, where the molar fraction of In x Ga 1-x N is the molar fraction of the N-type In x Ga 1-x N triangular island, and the thickness of Al x1 Ga 1-x1 N is less than 2 nm, x1 = 2.5×x ± 0.

05.

5. The dual-emitting direction Micro-LED structure according to claim 1, characterized in that: The left and right groups of quantum wells are symmetrically covered on the top of the strain control layer 104, with the same area and not connected to each other. Their shapes are consistent with the inclined surface of the GaN three-dimensional triangular island 103. When the wavelengths of the quantum wells are red, green, and blue, the number of quantum well pairs is 1 to 2 pairs, 2 to 4 pairs, and 3 to 5 pairs, respectively. The layer structure of the quantum well is In x2 Ga 1-x2 N / GaN / Al x3 Ga 1-x3 N / GaN, where x3 = 2.5 x2 ± 0.05, and In x2 Ga 1-x2 The thickness of N is 2 to 4 nm, and the two layers of GaN and Al x3 Ga 1-x3 The total thickness of N does not exceed 6 nm.

6. The dual-emitting direction Micro-LED structure according to claim 1, characterized in that: The carrier regulation layer 106 is one of an electron blocking layer and a hole injection layer; wherein the electron blocking layer is an Al2O3 layer having 2 to 8 cycles and a single cycle thickness of less than 8 nm. y1 Ga (1-y1) N / GaN superlattice, where the molar composition y1 is between 0.1 and 0.6 and Al y1 Ga (1-y1) The hole injection layer is P-doped with an overall thickness of less than 30nm Al y2 Ga (1-y2) N / In y3 Ga (1-y3) N / GaN superlattice, Mg doping concentration is 5×10 17 cm -3 ~1×10 19 cm -3 The hole concentration is not higher than 1×10 18 cm -3 .

7. The dual-emitting direction Micro-LED structure according to claim 1, characterized in that: P-type In y Ga 1-y The thickness of the N layer 107 is between 50 and 200 nm, and the molar composition y is between 0 and 0.

15. When y=0, it is GaN. The Mg element doping concentration is 2×10 19 cm -3 ~5×10 19 cm -3 The hole concentration is not less than 1×10 18 cm -3 ; Among them, P type In y Ga 1-y In the 5-30 nm thickness region on the upper surface of the N layer 107, the doping concentration of the Mg element is not less than 1×10 20 cm -3 , the hole concentration is not less than 5×10 18 cm -3 .

8. A method for preparing a Micro-LED structure with dual emission directions, characterized in that: The micro-LED structure includes an N-type GaN layer 101 with a non-polar upward crystal plane, a mask layer 102 containing a microhole array, an N-type In layer 103 with an In composition of 0≤x≤0.35, and a plurality of other layers. x Ga 1-x N triangle island 103, strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In with In composition y y Ga 1-y N layer 107, and P type In y Ga 1-y The N-type GaN layer 107 has a PL electrode 108 and a PR electrode 109 that have good ohmic contact, and an N-type GaN layer 1010 that has good ohmic contact. x Ga 1-x The bottom of the N triangle island 103 is obtained by epitaxial growth upward from the microholes in the mask layer 102, and includes two left-right symmetrical triangular slopes and a triangular side surface perpendicular to the bottom surface. In addition, the strain control layer 104, the quantum well layer 105, the carrier control layer 106, the P-type In y Ga 1-y The N layer 107 and the PL electrode 108 (or the PR electrode 109) are both symmetrically arranged on the N-type In x Ga 1-x The parameters of the same structure are exactly the same; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PL electrode 108, the N-electrode 1010 and the left side x Ga 1-x The N triangle island slopes form the Micro-LED structure L; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PR electrode 109, the N-electrode 1010 and the right side x Ga 1-x The N triangular island slope forms the Micro-LED structure R. The N electrode 1010 is disposed on the top of the N-type GaN layer 101 whose upward crystal surface is a non-polar surface. x Ga 1-x In front of the two inclined surfaces of the N triangle island, the N electrode 1010 and the N-type In x Ga 1-x N triangle island 103 no contact. The preparation method of the Micro-LED structure includes the following steps: a) preparing a non-polar N-type GaN template as the N-type GaN layer 101 whose upward crystal plane is a non-polar plane, or epitaxially growing a layer of N-type GaN film whose upward crystal plane is a non-polar plane on a sapphire, Si or SiC substrate as the N-type GaN layer 101; b) preparing a non-metallic compound dielectric layer on the N-type GaN layer 101 whose upward crystal surface is a non-polar surface, and using micro-machining technology to process a micro-hole structure on the dielectric layer to form a mask layer 102 containing a micro-hole array, exposing the N-type GaN layer 101 below; c) Selective epitaxial growth is performed using the micropores, and then lateral epitaxy is performed by controlling the epitaxial growth temperature, V / III ratio, reaction chamber pressure, carrier gas, and reactant source flow rate to form an N-type In with an In component of 0≤x≤0.

35. x Ga 1-x N Delta Island 103; d) In N-type In x Ga 1-x The strain control layer 104 is epitaxially grown on the basis of the N-type triangular island 103, and combined with micro-machining technology, the strain control layer 104 covers the entire N-type In x Ga 1-x N triangle island 103 left and right two slopes, but not covered by N type In x Ga 1-x At the edge in the middle of N triangle island 103; e) epitaxially growing a quantum well layer 105 on the strain control layer 104 so that the quantum well symmetrically covers the top of the strain control layer 104; f) epitaxially growing a carrier regulation layer 106 on the quantum well layer 105 and covering the quantum well layer 105; g) epitaxially growing P-type In on the carrier regulation layer 106 y Ga 1-y N layer 107, covering the carrier regulation layer 106; h) Using standard micromachining technology, the corresponding position of the N electrode 1010 on the mask layer 102 is etched to expose the underlying N-type GaN layer 101; one of the evaporation coating and magnetron sputtering techniques is used to complete the PL electrode 108, the PR electrode 109 and the N electrode 1010 to complete the preparation of this Micro-LED structure.

9. A method for preparing a Micro-LED structure with dual emission directions, characterized in that: The micro-LED structure includes an N-type GaN layer 101 with a non-polar upward crystal plane, a mask layer 102 containing a microhole array, an N-type In layer 103 with an In composition of 0≤x≤0.35, and a plurality of other layers. x Ga 1-x N triangle island 103, strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In with In composition y y Ga 1-y N layer 107, and P type In y Ga 1-y The N-type GaN layer 107 has a PL electrode 108 and a PR electrode 109 that have good ohmic contact, and an N-type GaN layer 1010 that has good ohmic contact. x Ga 1-x The bottom of the N triangle island 103 is obtained by epitaxial growth upward from the microholes in the mask layer 102, and includes two left-right symmetrical triangular slopes and a triangular side surface perpendicular to the bottom surface. In addition, the strain control layer 104, the quantum well layer 105, the carrier control layer 106, the P-type In y Ga 1-y The N layer 107 and the PL electrode 108 (or the PR electrode 109) are both symmetrically arranged on the N-type In x Ga 1-x The parameters of the same structure are exactly the same; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PL electrode 108, the N-electrode 1010 and the left side x Ga 1-x The N triangle island slopes form the Micro-LED structure L; the strain control layer 104, quantum well layer 105, carrier control layer 106, P-type In y Ga 1-y The N-type In layer 107, the PR electrode 109, the N-electrode 1010 and the right side x Ga 1-x The N triangular island slopes form a Micro-LED structure R. The N electrode 1010 is disposed at the bottom of the GaN layer 101 whose upward crystal surface is a non-polar surface, directly covering the bottom of the entire N-type GaN layer 101 . The preparation method of the Micro-LED structure includes the following steps: a) preparing a non-polar N-type GaN template as the N-type GaN layer 101 whose upward crystal plane is a non-polar plane, or epitaxially growing a layer of N-type GaN film whose upward crystal plane is a non-polar plane on a sapphire, Si or SiC substrate as the N-type GaN layer 101; b) preparing a non-metallic compound dielectric layer on the N-type GaN layer 101 whose upward crystal surface is a non-polar surface, and using micro-machining technology to process a micro-hole structure on the dielectric layer to form a mask layer 102 containing a micro-hole array, exposing the N-type GaN layer 101 below; c) Selective epitaxial growth is performed using the micropores, and then lateral epitaxy is performed by controlling the epitaxial growth temperature, V / III ratio, reaction chamber pressure, carrier gas, and reactant source flow rate to form an N-type In with an In component of 0≤x≤0.

35. x Ga 1-x N Delta Island 103; d) In N-type In x Ga 1-x The strain control layer 104 is epitaxially grown on the basis of the N-type triangular island 103, and combined with micro-machining technology, the strain control layer 104 covers the entire N-type In x Ga 1-x N triangle island 103 left and right two slopes, but not covered by N type In x Ga 1-x At the edge in the middle of N triangle island 103; e) epitaxially growing a quantum well layer 105 on the strain control layer 104 so that the quantum well symmetrically covers the top of the strain control layer 104; f) epitaxially growing a carrier regulation layer 106 on the quantum well layer 105 and covering the quantum well layer 105; g) epitaxially growing P-type In on the carrier regulation layer 106 y Ga 1-y N layer 107, covering the carrier regulation layer 106; h) using one of the evaporation coating and magnetron sputtering techniques to prepare the PL electrode 108 and the PR electrode 109; i) The structure above the N-type GaN layer 101 is peeled off using a peeling process, and an N-electrode 1010 is prepared at the original bottom of the N-type GaN layer 101 using a technique selected from evaporation coating and magnetron sputtering to complete the preparation of the Micro-LED structure.

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