Preparation method of light-emitting structure and light-emitting structure

Abstract

The invention discloses a preparation method of a light-emitting structure and the light-emitting structure. The preparation method comprises the following steps: acquiring an initial light-emitting structure; removing the substrate of the initial light-emitting structure, and exposing the first semiconductor layer on the surface layer; forming a metal layer on the surface layer of the first semiconductor layer; performing electrochemical corrosion on the metal layer to form a plurality of first micropores extending towards the first semiconductor layer to obtain a first optical waveguide structure; and continuously performing electrochemical corrosion along the first micropores to the first semiconductor layer until a plurality of second micropores are formed in the first semiconductor layer, thereby obtaining a second optical waveguide structure. According to the invention, the second optical waveguide structure with a variable refractive index is formed on the initial light-emitting structure in a preparation mode which is low in cost and does not need high-precision alignment, the second optical waveguide structure is used for collecting light rays, and the light extraction efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of LED preparation, and in particular to a preparation method of a light-emitting structure and a light-emitting structure. Background Art

[0002] QLED uses blue light to excite RQD and GQD to form three primary colors. During the process of process implementation, it is inevitable that there will be light crosstalk problems between adjacent pixels due to the excessive divergence angle of blue light.

[0003] In the past, one solution to reduce optical crosstalk was to add light-blocking walls (reflective metal or light-absorbing material), which required high processing precision and high cost. Another solution was to use microlenses to change the light output angle. At present, nanoimprinting technology is not mature enough, with high manufacturing cost and low precision. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for preparing a light-emitting structure and a light-emitting structure, so as to solve the problems of high processing precision and high manufacturing cost in the preparation of the light-emitting structure in the related art.

[0005] In order to achieve the above object, the present invention provides a method for preparing a light-emitting structure, comprising:

[0006] obtaining an initial light-emitting structure;

[0007] Removing the substrate of the initial light-emitting structure to expose the first semiconductor layer on the surface;

[0008] forming a metal layer on a surface of the first semiconductor layer;

[0009] Electrochemically corroding the metal layer to form a plurality of first microholes extending toward the first semiconductor layer to obtain a first optical waveguide structure;

[0010] Electrochemical etching is continued along the first microhole to the first semiconductor layer until a plurality of second microholes are formed on the first semiconductor layer to obtain a second optical waveguide structure.

[0011] Further, electrochemically corroding the metal layer includes:

[0012] Arranging a protection structure on the initial light-emitting structure, wherein the protection structure at least covers the periphery of the initial light-emitting structure and exposes the surface of the metal layer;

[0013] The metal layer is electrified, and the surface of the metal layer is flushed with an acid solution to form a plurality of first micropores extending toward the first semiconductor layer.

[0014] Furthermore, electrochemically corroding the metal layer further comprises:

[0015] Arranging a conductive rubber ring on a part of the surface of the metal layer, wherein the conductive rubber ring is close to the edge of the metal layer;

[0016] A portion of the protective structure covers the conductive rubber ring, and the conductive rubber ring is electrically connected to a power source through a wire.

[0017] Furthermore, during the electrochemical corrosion of the metal layer and the first semiconductor layer, the depth, size and density of the first micropores and the second micropores are controlled by controlling the corrosion time, the corrosion voltage and observing the change of the corrosion current.

[0018] Furthermore, during the electrochemical corrosion process, the corrosion time and the corrosion voltage are adjusted according to the oxidizing property of the selected acid solution so that the depth, size and density of the first micropores and the second micropores meet the designed values.

[0019] Furthermore, the thickness of the first semiconductor layer is greater than 3 μm, and the doping concentration is greater than 3e18.

[0020] Furthermore, the thickness of the metal layer is greater than or equal to the aperture of the first micropores.

[0021] Further, the substrate of the LED is removed to expose the first semiconductor layer on the surface, including:

[0022] The substrate is removed by laser stripping, and the first semiconductor layer on the surface is exposed by grinding or pickling.

[0023] According to another aspect of the present application, a light emitting structure is provided, comprising:

[0024] An initial light emitting structure, the initial light emitting structure comprising a first semiconductor layer;

[0025] A metal layer, disposed on the first semiconductor layer;

[0026] The second optical waveguide structure includes a plurality of first micropores and a plurality of second micropores, wherein the first micropores are located in the metal layer and extend to the surface of the first semiconductor layer, and the second micropores are located in the first semiconductor layer and communicate with the first micropores.

[0027] Further, any one of the plurality of the first micropores corresponds to a plurality of the second micropores.

[0028] In the embodiment of the present invention, an initial light-emitting structure is obtained; the substrate of the initial light-emitting structure is removed to expose the first semiconductor layer on the surface; a metal layer is formed on the surface of the first semiconductor layer; the metal layer is electrochemically corroded to form a plurality of first microholes extending toward the first semiconductor layer to obtain a first optical waveguide structure; the electrochemical corrosion is continued along the first microholes to the first semiconductor layer until a plurality of second microholes are formed on the first semiconductor layer to obtain a second optical waveguide structure, thereby realizing a second optical waveguide structure with a changed refractive index formed on the initial light-emitting structure in a preparation method that is low-cost and does not require high-precision alignment, and the first microholes and the second microholes in the second optical waveguide structure are used to converge light, and the technical effect of improving light extraction efficiency is achieved, thereby solving the problem of high processing precision requirements and high manufacturing costs in the preparation of the light-emitting structure in the related art;

[0029] Furthermore, since the preparation of the first optical waveguide structure utilizes the property of the metal oxide layer that the metal layer can self-assemble to form a highly ordered nanoscale pore structure during the electrochemical corrosion process, its preparation process is simple, the structural parameters are adjustable, the insulation and stability are good, and the adhesion to the substrate is good, the mechanical strength is high, and the yield of the product can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, so that other features, purposes and advantages of the present invention become more obvious. The accompanying drawings of the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 is a schematic flow chart of a preparation method according to an embodiment of the present invention;

[0032] Figure 2 is a simulation schematic diagram of three point light sources according to an embodiment of the present invention;

[0033] Figure 3 is a simulation schematic diagram of forming an optical waveguide structure only on the first semiconductor layer according to an embodiment of the present invention;

[0034] Figure 4 is a simulation schematic diagram of forming a first optical waveguide structure and a second optical waveguide structure according to an embodiment of the present invention;

[0035] Figure 5 is a schematic diagram of a cross-sectional structure of an initial light-emitting structure according to an embodiment of the present invention;

[0036] Figure 6 is a schematic diagram of a cross-sectional structure after a metal layer is formed on an initial light-emitting structure according to an embodiment of the present invention;

[0037] Figure 7is a schematic cross-sectional structural diagram of forming a first optical waveguide structure on an initial light-emitting structure according to an embodiment of the present invention;

[0038] Figure 8 is a schematic cross-sectional structural diagram of forming a second optical waveguide structure on an initial light emitting structure according to an embodiment of the present invention;

[0039] Fig. 9 is a schematic cross-sectional structural diagram of forming a second optical waveguide structure on an initial light emitting structure according to another embodiment of the present invention;

[0040] Fig.10 is a schematic diagram of an electrochemical corrosion device according to an embodiment of the present invention;

[0041] Among them, 1 is an initial light emitting structure, 10 is a first semiconductor layer, 2 is a metal layer, 3 is a first microhole, 4 is a first optical waveguide structure, 5 is a second microhole, 6 is a second optical waveguide structure, 7 is a base, 70 is a horizontal part, 71 is a vertical part, 72 is a pressing part, and 8 is a conductive rubber. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged under appropriate circumstances to facilitate the embodiments of the present invention described herein.

[0044] In the present invention, the directions or positional relationships indicated by the terms "upper", "lower", "inner", etc. are based on the directions or positional relationships shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

[0045] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0046] In addition, the terms "disposed", "provided with", "connected", "fixed" and the like should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In addition, the term "plurality" shall mean two or more.

[0048] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0049] To solve relevant technical problems, such as Figure 1 As shown, an embodiment of the present invention provides a method for preparing a light-emitting structure, comprising:

[0050] S10, obtaining an initial light-emitting structure 1;

[0051] S20, removing the substrate of the initial light emitting structure 1 to expose the first semiconductor layer 10 on the surface;

[0052] S30, forming a metal layer 2 on the surface of the first semiconductor layer 10;

[0053] S40, electrochemically corroding the metal layer 2 to form a plurality of first microholes 3 extending toward the first semiconductor layer 10, thereby obtaining a first optical waveguide structure 4;

[0054] S50 , continue electrochemically etching along the first microhole 3 to the first semiconductor layer 10 , until a plurality of second microholes 5 are formed on the first semiconductor layer 10 , thereby obtaining a second optical waveguide structure 6 .

[0055] like Figure 2 As shown in the figure, three 120° point light sources are used to simulate the LED emitting angle in the air. Figure 3 As shown, the case where the optical waveguide structure is only made on the first semiconductor layer 10 of the initial light-emitting structure 1 is simulated. It can be seen that at this time, the light has a focusing effect, but the light extraction efficiency is low.

[0056] For this reason, in the preparation method of this embodiment, Figure 4 As shown, the first semiconductor layer 10 and the metal layer 2 are combined to form an optical waveguide structure on the light-emitting side of the initial light-emitting structure 1, and finally a second optical waveguide structure 6 with a changed refractive index is formed. The second optical waveguide structure 6 with a changed refractive index is used to converge the light and improve the light extraction efficiency.

[0057] The metal layer 2 can be an AL layer or other metal layer. When the metal layer 2 is an AL layer, the process of making a waveguide structure for the metal layer 2 is the process of preparing an AAO template. Specifically, the AAO template is an aluminum oxide with a highly ordered nanoscale pore structure formed by self-assembly in an acidic solution. It has a simple preparation process, adjustable structural parameters, good insulation and stability, and is transparent in visible light and most infrared light regions. The porous AAO template has an extinction coefficient close to 0, the refractive index can be adjusted by the aperture and pores, the oxide thickness can be adjusted according to the surface coating technology, and the porous AAO has good adhesion to the substrate and high mechanical strength. It is suitable as an optical waveguide layer in full-color Micro LED to reduce the light beam divergence angle of the LED and reduce light crosstalk. It can be used to prepare micro-projection equipment based on full-color Micro LED, or used in AR equipment.

[0058] Moreover, the biggest difference in the preparation process from other anti-light crosstalk structures (such as adding light blocking walls or using lens lamps) is that it only requires electron beam evaporation and electrochemical corrosion equipment, which is low-cost, does not require high-precision alignment, and has a high fault tolerance. At the same time, the preparation process of the AAO template is mature and does not require a lot of experiments and funds to obtain parameters.

[0059] Based on this, in this embodiment, the AAO template is introduced into the initial light emitting structure 1, and the first optical waveguide structure 4 located on the surface of the first semiconductor layer 10 is first formed during the preparation process. Specifically, during the preparation, the substrate of the initial light emitting structure 1 is first removed to obtain Figure 5 In the structure shown, in this step, the substrate can be removed by laser stripping, and the first semiconductor layer 10 on the surface is exposed by grinding or pickling. In this embodiment, the first semiconductor layer is an N-GaN layer. Of course, other methods can also be used for removal, which is not limited in this embodiment. In one embodiment, the substrate of the initial light-emitting structure 1 can be a sapphire substrate.

[0060] After removing the substrate, the first semiconductor layer 10 of the initial light emitting structure 1 is exposed, and an AAO template is prepared on the surface of the first semiconductor layer 10. Specifically, Figure 6 As shown, a metal layer 2 with a certain thickness can be first formed on the surface of the first semiconductor layer 10, and electron beam evaporation or chemical plating can be used. The thickness of the metal layer 2 can be adjusted according to actual needs, and there is no limitation on it in this embodiment. The metal layer 2 completely covers the surface of the first semiconductor layer 10, and its coverage area can correspond to one pixel or multiple pixels of the initial light-emitting structure 1. In order to improve the production efficiency and the surface consistency of the metal layer 2, it is preferred that the metal layer 2 completely covers all the pixels of the initial light-emitting structure 1 in one preparation process.

[0061] like Figure 7As shown, after the metal layer 2 is formed, the metal layer 2 is electrochemically etched to form a plurality of first micropores 3 extending toward the first semiconductor layer 10, and at this time, a first optical waveguide structure 4, i.e., an AAO template, can be formed on the surface of the first semiconductor layer 10. According to the formation process of the AAO template, the first micropores 3 are highly ordered nanoscale holes, and the aperture of the first micropores 3 and the spacing between adjacent first micropores 3 can be adjusted during the electrochemical etching process, so that the refractive index of the AAO template reaches a set value.

[0062] like Figure 8 As shown, after the first optical waveguide structure 4 is prepared, electrochemical etching can be continued along the first micropore 3 to obtain the second optical waveguide structure 6. Specifically, since the first micropore 3 is a nano-micropore extending toward the surface of the first semiconductor layer 10, Figure 8 As shown, the acid solution can be further corroded through the first micropore 3 by electrochemical corrosion until it contacts the first semiconductor layer 10, thereby electrochemically corroding the first semiconductor layer 10 to form a second micropore 5 with a certain depth. The depth of the second micropore 5 should be less than the thickness of the first semiconductor layer 10, so as not to affect the normal light emission of the initial light emitting structure 1. After the second micropore 5 is formed by electrochemical corrosion, a second optical waveguide structure 6 with a changed refractive index can be obtained. In this embodiment, the second optical waveguide structure 6 is a waveguide structure including the first micropore 3 and the second micropore 5.

[0063] Specifically, the light-emitting structure prepared based on the above preparation method has two layers of micropores with different refractive indices, and the inner wall refractive index of the first micropore 3 located in the upper layer is smaller than the inner wall refractive index of the second micropore 5 located in the lower layer. According to the simulation structure, compared with the case where only the optical waveguide structure is made on GaN, the light-emitting structure has a significant light convergence effect and increases the light extraction efficiency.

[0064] In addition, in this embodiment, the metal layer 2 is directly grown on the first semiconductor layer 10 of the initial light emitting structure 1, and then the first optical waveguide structure 4 is formed at low cost according to the physical properties of the metal layer 2 by electrochemical corrosion (for example, when the metal layer is an AL layer, the AAO template is formed by electrochemical corrosion). On this basis, the second microhole 5 is formed on the first semiconductor layer 10 along the first microhole 3 by electrochemical corrosion, and finally the second optical waveguide structure 6 with a refractive index change is formed. The whole preparation process is low-cost, does not require high-precision alignment, has a high fault tolerance rate, and the preparation process of the AAO template is mature, and does not require a lot of experiments and funds to find parameters.

[0065] Since the first micropores 3 and the second micropores 5 are both formed by electrochemical corrosion, in order to avoid the electrochemical corrosion process from affecting the non-target corrosion surface of the initial light-emitting structure 1, it is necessary to control the contact position of the acid solution and the initial light-emitting structure 1 and the metal layer 2 so that the acid solution only contacts the surface of the metal layer 2 and does not contact the periphery of the initial light-emitting structure 1 and the metal layer 2.

[0066] To this end, in the preparation method of this embodiment, electrochemically corroding the metal layer 2 includes:

[0067] Arranging a protective structure on the initial light-emitting structure 1, the protective structure is made of corrosion-resistant material, and the protective structure at least covers the periphery of the initial light-emitting structure 1 and exposes the surface of the metal layer 2;

[0068] The metal layer 2 is electrified, and the surface of the metal layer 2 is flushed with an acid solution to form a plurality of first micropores 3 extending toward the first semiconductor layer 10 .

[0069] In this embodiment, the protective structure has different arrangements according to the structural forms of the initial light-emitting structure 1 and the metal layer 2. In one embodiment, the protective structure can be sleeved on the initial light-emitting structure 1, one of the end faces of the protective structure is flush with the surface of the metal layer 2, and the protective structure is made of corrosion-resistant material. The protective structure blocks the acid solution from contacting the periphery of the metal layer 2 and the periphery of the initial light-emitting structure 1, so that during the electrochemical corrosion process, the acid solution only contacts the surface area of ​​the metal layer 2. After the metal layer 2 completes the electrochemical corrosion to form the first micropore 3, the acid solution contacts the first semiconductor layer 10 after passing through the first micropore 3 in the region, thereby corroding the first semiconductor layer 10 until the second micropore 5 is formed.

[0070] Since the metal layer 2 needs to be energized during the electrochemical corrosion process, in order to achieve the energization, the electrochemical corrosion of the metal layer 2 in this embodiment further includes:

[0071] Eight circles of conductive rubber are arranged on a portion of the surface of the metal layer 2 , and the eight circles of conductive rubber are close to the edge of the metal layer 2 .

[0072] Specifically, in this embodiment, the conductive rubber 8 is tightly attached to the surface of the metal layer 2 and covers the edge area of ​​the surface of the metal layer 2, and the conductive rubber 8 is electrically connected to the power supply through a wire. In one embodiment, the conductive rubber 8 is set in a ring shape and attached to the surface of the metal layer 2. According to the structural form of the metal layer 2, when the metal layer 2 is square, the conductive rubber 8 can be a square ring, and when the metal layer 2 is circular, the conductive rubber 8 can be a circular ring. The conductive rubber 8 is a conductive particle of glass silver-plated, aluminum silver-plated, silver, etc. uniformly distributed in the silicone rubber, and the conductive particles are brought into contact by pressure to achieve conductivity. Therefore, after the conductive rubber 8 is pressed onto the surface of the metal layer 2, the metal layer 2 and the initial light-emitting structure 1 can be energized through the conductive rubber 8, so that electrochemical corrosion is performed under the action of the acid solution.

[0073] After the conductive rubber 8 is provided, it is necessary to reduce the corrosion effect of the acid solution on the conductive rubber 8. For this purpose, a part of the protective structure in this embodiment covers the conductive rubber 8, and the conductive rubber 8 is electrically connected to the power supply through a wire. After the protective structure is provided, the conductive rubber 8 can be protected to a certain extent when the acid solution is flushed from bottom to top, thereby reducing the effect of the acid solution on the conductive rubber 8.

[0074] Based on the above implementation, Fig.10 As shown, this embodiment provides an electrochemical corrosion device as the protective structure of the above-mentioned embodiment to complete the above-mentioned electrochemical corrosion process. The electrochemical corrosion device includes a base 7 made of corrosion-resistant material, and the base 7 includes a horizontal portion 70, a vertical portion 71 arranged on the side of the horizontal portion 70 and extending downward, and a horizontally extending pressing portion 72 is provided at the lower end of the vertical portion 71, and the pressing portion 72 has an opening corresponding to the corrosion surface. The initial light-emitting structure 1 with a metal layer 2 can be assembled to the lower surface of the horizontal portion 70, and the conductive rubber 8 is pressed on the lower surface of the metal layer 2 through the pressing portion 72. The inner side of the vertical portion 71 is tightly attached to the initial light-emitting structure 1 and the ring side of the metal layer 2, and the acid solution can flush the corrosion surface through the opening on the pressing portion 72 to perform electrochemical corrosion.

[0075] Since the first micropore 3 needs to extend to the surface of the first semiconductor layer 10, the depth of the second micropore 5 needs to be smaller than the depth of the first semiconductor layer 10, and the aperture of the first micropore 3 and the second micropore 5 will affect the refractive index, and the density will affect the overall light extraction effect. Therefore, in the process of electrochemical corrosion, it is necessary to control the depth, aperture and density of the first micropore 3 and the second micropore 5. Specifically, according to the process of electrochemical corrosion, in the process of electrochemically corroding the metal layer 2 and the first semiconductor layer 10, the depth, size and density of the first micropore 3 and the second micropore 5 are controlled by controlling the corrosion time, corrosion voltage and observing the change of corrosion current.

[0076] In addition, during the electrochemical corrosion process, it is also necessary to adjust the corrosion time and corrosion voltage according to the oxidizing property of the selected acid solution so that the depth, size and density of the first micropore 3 and the second micropore 5 meet the design value. It can be understood that the stronger the oxidizing property of the selected acid solution or the higher the concentration (the lower the pH value), the smaller the corrosion holes of the same area and the higher the density, and the smaller the corrosion voltage required to achieve the same corrosion current. Conversely, the weaker the oxidizing property of the selected acid solution, the larger the corrosion holes of the same area and the lower the density, and the greater the corrosion voltage required to achieve the same corrosion current.

[0077] According to the process of electrochemical corrosion, when the voltage is constant, the corrosion rate remains constant, and the corrosion depth and corrosion area can be obtained according to the corrosion time. As the corrosion depth and area change, the current passing through the material to be corroded will also change accordingly. Therefore, the depth, pore size and density of the first micropore 3 and the second micropore 5 can be controlled by controlling the corrosion time and observing the change of the corrosion current. In addition, when the voltage increases, the corrosion rate increases. Therefore, under the same time, a larger voltage will corrode to form larger micropores, reducing the density per unit area. Therefore, the depth, pore size and density of the first micropore 3 and the second micropore 5 can also be controlled by controlling the corrosion voltage.

[0078] Due to the difference in properties between the metal layer 2 and the first semiconductor layer 10, generally speaking, during the electrochemical corrosion process, a plurality of second micropores 5 will be formed in the area corresponding to a first micropore 3 on the first semiconductor layer 10, and the greater the number of second micropores 5, the better the light extraction effect of the formed optical waveguide structure.

[0079] In one embodiment, in order to facilitate electrochemical corrosion of the first semiconductor layer 10, the thickness of the first semiconductor layer 10 in this embodiment is greater than 3 μm, and the doping concentration is greater than 3e18. In one embodiment, in order to enable the first micropore to have a satisfactory light extraction effect, the thickness of the metal layer 2 is greater than or equal to the aperture of the first micropore 3.

[0080] Specifically, it should be noted that when the thickness of the metal layer 2 is smaller than the aperture of the first micropore 3, that is, when the hole depth of the first micropore 3 is smaller than the aperture, the cross section of the first micropore 3 is a flat rectangle, and most of the light emitted from the initial light-emitting structure 1 cannot contact the wall of the first micropore 3, resulting in poor light extraction effect. Therefore, in order to ensure sufficient light extraction effect, the hole depth of the first micropore 3 must be at least equal to the aperture, that is, the thickness of the metal layer 2 is greater than or equal to the aperture of the first micropore 3.

[0081] In one embodiment, the more micropores there are on the same pixel, the higher the light extraction efficiency and the better the light focusing effect. Generally, there are at least 25 micropores on one pixel. When the micropores are designed to be smaller, the thickness of the metal layer 2 can be smaller.

[0082] like Figure 8 As shown, according to another aspect of the present application, a light emitting structure is provided, including:

[0083] An initial light emitting structure 1, the initial light emitting structure 1 comprising a first semiconductor layer 10;

[0084] The metal layer 2 is disposed on the first semiconductor layer 10;

[0085] The second optical waveguide structure 6 includes a plurality of first micropores 3 and a plurality of second micropores 5 . The first micropores 3 are located in the metal layer 2 and extend to the surface of the first semiconductor layer 10 . The second micropores 5 are located in the first semiconductor layer 10 and communicate with the first micropores 3 .

[0086] In this embodiment, the second optical waveguide structure 6 formed on the light emitting structure includes a first micropore 3 and a second micropore 5, wherein the first micropore 3 is formed in the metal layer 2, and the second micropore 5 is formed in the first semiconductor layer 10. According to the physical properties of the material, the refractive index of the inner wall of the first micropore 3 will be significantly smaller than the refractive index of the inner wall of the second micropore 5, so after the light emitted from the first semiconductor layer 10 is reflected on the inner walls of the second micropore 5 and the first micropore 3 in turn, the change in the refractive index of the inner wall and the depth of the hole can be used to achieve light convergence and improve light extraction efficiency.

[0087] To avoid affecting the function of the first semiconductor layer 10, the depth of the second micropores 5 should be less than the thickness of the first semiconductor layer 10. Since the light emitted by the initial light emitting structure 1 needs to be reflected in the first micropores 3 and the second micropores 5, the more micropores the better to improve the light emitting effect. Fig. 9 As shown, a plurality of second micropores 5 should be formed in the region corresponding to the first micropores 3. That is, any first micropore 3 among the plurality of first micropores 3 corresponds to a plurality of second micropores 5.

[0088] Similarly, the distribution density, hole depth and other parameters of the second micropores 5 can still be controlled during the electrochemical corrosion process. For the structure in which the first micropores 3 are formed on the metal layer 2, the preparation method of the AAO template can be used for preparation. Specifically, the AAO template is an aluminum oxide with a highly ordered nanoscale pore structure formed by self-assembly in an acidic solution. It has a simple preparation process, adjustable structural parameters, good insulation and stability, and is transparent in the visible light and most infrared light regions. The porous AAO template has an extinction coefficient close to 0, the refractive index can be adjusted by the aperture and pores, the oxide thickness can be adjusted according to the surface coating technology, and the porous AAO has good adhesion to the substrate and high mechanical strength. It is suitable for use as an optical waveguide layer in full-color Micro LEDs to reduce the light beam divergence angle of the LED and reduce light crosstalk. It can be used to prepare micro-projection devices based on full-color Micro LEDs, or used on AR devices.

[0089] For the AAO template, the AAO template completely covers the surface of the first semiconductor layer 10, and its coverage area may correspond to one pixel or multiple pixels of the initial light-emitting structure 1. In order to improve production efficiency and surface consistency, it is preferred that the AAO template completely covers all pixels of the initial light-emitting structure 1 in one preparation process.

[0090] The second optical waveguide structure in the light-emitting structure of this embodiment has two layers of micropores with different refractive indices, and the refractive index of the inner wall of the first micropore 3 located in the upper layer is smaller than the refractive index of the inner wall of the second micropore 5 located in the lower layer. According to the simulation structure, the light-emitting structure has a significant light convergence effect compared with the case where the optical waveguide structure is only made on GaN, and at the same time increases the light extraction efficiency.

[0091] In addition, since the preparation process of AAO template is mature and the preparation cost is low, and no high-precision alignment is required, while ensuring that the light-emitting structure has sufficient light focusing performance and light extraction efficiency, it greatly reduces the production cost and difficulty of the light-emitting structure and improves the product yield.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Within the spirit and principle of the present invention, any modification, equivalent replacement, improvement, etc. made shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a light-emitting structure, characterized in that: include: obtaining an initial light-emitting structure; Removing the substrate of the initial light-emitting structure to expose the first semiconductor layer on the surface; forming a metal layer on a surface of the first semiconductor layer; Electrochemically corroding the metal layer to form a plurality of first microholes extending toward the first semiconductor layer to obtain a first optical waveguide structure; Electrochemical etching is continued along the first microhole to the first semiconductor layer until a plurality of second microholes are formed on the first semiconductor layer to obtain a second optical waveguide structure.

2. The preparation method according to claim 1, characterized in that: The electrochemically corroding the metal layer comprises: Arranging a protection structure on the initial light-emitting structure, wherein the protection structure at least covers the periphery of the initial light-emitting structure and exposes the surface of the metal layer; The metal layer is electrified, and the surface of the metal layer is flushed with an acid solution to form a plurality of first micropores extending toward the first semiconductor layer.

3. The preparation method according to claim 2, characterized in that: The electrochemically corroding the metal layer further comprises: Arranging a conductive rubber ring on a part of the surface of the metal layer, wherein the conductive rubber ring is close to the edge of the metal layer; A portion of the protective structure covers the conductive rubber ring, and the conductive rubber ring is electrically connected to a power source through a wire.

4. The method for preparing a light emitting structure according to claim 1, characterized in that: During the electrochemical corrosion of the metal layer and the first semiconductor layer, the depth, size and density of the first micropores and the second micropores are controlled by controlling the corrosion time, the corrosion voltage and observing the change of the corrosion current.

5. The method for preparing a light emitting structure according to claim 4, characterized in that: During the electrochemical corrosion process, the corrosion time and the corrosion voltage are adjusted according to the oxidizing property of the selected acid solution so that the depth, size and density of the first micropores and the second micropores meet the designed values.

6. The method for preparing a light emitting structure according to claim 1, characterized in that: The thickness of the first semiconductor layer is greater than 3 μm, and the doping concentration is greater than 3e18.

7. The method for preparing a light emitting structure according to claim 1, characterized in that: The thickness of the metal layer is greater than or equal to the aperture of the first micropore.

8. The method for preparing a light emitting structure according to claim 1, characterized in that: The method of removing the substrate of the LED to expose the first semiconductor layer on the surface includes: The substrate is removed by laser stripping, and the surface first semiconductor layer is exposed by grinding or pickling.

9. A light emitting structure, characterized in that: include: An initial light emitting structure, the initial light emitting structure comprising a first semiconductor layer; A metal layer, disposed on the first semiconductor layer; The second optical waveguide structure includes a plurality of first micropores and a plurality of second micropores, wherein the first micropores are located in the metal layer and extend to the surface of the first semiconductor layer, and the second micropores are located in the first semiconductor layer and communicate with the first micropores.

10. The light emitting structure according to claim 9, characterized in that: Any one of the plurality of the first micropores corresponds to a plurality of the second micropores.

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