Light-emitting device, preparation method thereof and light-emitting substrate

Abstract

The invention provides a light-emitting device and a preparation method thereof, and a light-emitting substrate, and relates to the technical field of display, the light-emitting device comprises a substrate, an epitaxial structure located at one side of the substrate, a plurality of insulating parts and a plurality of metal particles; a plurality of columnar structures are arranged on the epitaxial structure, and a groove is formed between every two adjacent columnar structures; the insulating part is arranged in the groove, and the insulating part covers the bottom of the groove and at least partial area of the side wall of the groove; the plurality of metal particles are positioned on the surface, far away from the substrate, of the insulating part, and are insulated from the epitaxial structure; the light-emitting device is simple in structure and high in light-emitting efficiency.

Description

Technical Field

[0001] The present application relates to the display field, and in particular to a light-emitting device and a preparation method thereof, and a light-emitting substrate. Background Art

[0002] With the rapid development of display technology, Mini LED (Mini Light Emitting Diode) and Micro LED (Micro Light Emitting Diode) display products have attracted widespread attention. However, the luminous efficiency of the above two LED light-emitting devices in the related art is difficult to further improve. Summary of the invention

[0003] The present application provides a light-emitting device and a preparation method thereof, and a light-emitting substrate. The light-emitting device has a simple structure and improved light-emitting efficiency.

[0004] The embodiments of the present application adopt the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a light emitting device, the light emitting device comprising:

[0006] substrate;

[0007] An epitaxial structure located on one side of the substrate; a plurality of columnar structures are arranged on the epitaxial structure, and a groove is arranged between two adjacent columnar structures;

[0008] A plurality of insulating parts, wherein the insulating parts are arranged in the groove and cover at least a portion of the bottom of the groove and the sidewall of the groove;

[0009] A plurality of metal particles are located on a surface of the insulating portion away from the substrate, and the plurality of metal particles are insulated from the epitaxial structure.

[0010] In some light-emitting devices provided by embodiments of the present application, the epitaxial structure includes a buffer layer, a first semiconductor layer, a quantum well layer, and a second semiconductor layer sequentially arranged in a direction away from the substrate;

[0011] The average distance between the surface of the insulating portion away from the substrate and the substrate is greater than the average distance between the surface of the quantum well layer away from the substrate and the substrate.

[0012] In some light-emitting devices provided in the embodiments of the present application, the bottom of the groove includes a partial area of ​​the first semiconductor layer;

[0013] The columnar structure includes a partial region of the first semiconductor layer, a partial region of the quantum well layer, and a partial region of the second semiconductor layer, which are sequentially arranged in a direction away from the substrate; a side surface of the first semiconductor layer, a side surface of the quantum well layer, and a side surface of the second semiconductor layer in the columnar structure serve as a side wall of the groove,

[0014] Alternatively, the columnar structure includes a partial region of the quantum well layer and a partial region of the second semiconductor layer arranged in sequence along a direction away from the substrate; the side surfaces of the quantum well layer and the side surfaces of the second semiconductor layer in the columnar structure serve as side walls of the groove.

[0015] In some light-emitting devices provided in the embodiments of the present application, the columnar structure further includes a first conductive portion, and the first conductive portion is located on a side of a partial region of the second semiconductor layer away from the substrate;

[0016] The side surface of the first conductive layer in the columnar structure serves as the side wall of the groove.

[0017] In some light-emitting devices provided by embodiments of the present application, the insulating portion at least covers the side surfaces of the quantum well layer in the side walls of the groove.

[0018] In some light-emitting devices provided in the embodiments of the present application, the light-emitting device further comprises a passivation layer, wherein the passivation layer covers the bottom of the groove and the sidewall of the groove;

[0019] The insulating portion is located on a side of the passivation layer away from the bottom of the groove and the sidewall of the groove.

[0020] In some light-emitting devices provided in the embodiments of the present application, the light-emitting device further includes a color conversion portion;

[0021] The color conversion portion is located in a region between the insulating portion and the metal particles;

[0022] Alternatively, the color conversion portion and the insulating portion are an integrated structure.

[0023] In some light-emitting devices provided in embodiments of the present application, the light-emitting device further includes a second conductive portion, which covers the plurality of columnar structures, the plurality of metal particles and the gaps between the metal particles, and electrically connects the metal particles in the plurality of grooves together.

[0024] In some light-emitting devices provided in the embodiments of the present application, the light-emitting device further comprises a connecting electrode, a first electrode and a second electrode, a first opening is provided on the epitaxial structure and the conductive portion, and an orthographic projection of an outer contour of the first opening on the substrate partially overlaps with an orthographic projection of a first semiconductor layer of the epitaxial structure on the substrate; the conductive portion comprises a first conductive portion and a second conductive portion;

[0025] The connecting electrode is electrically connected to the first semiconductor layer through the first opening;

[0026] The light emitting device further comprises a dielectric layer, the dielectric layer covers the conductive portion and a partial area of ​​the connecting electrode, a second opening and a third opening are provided on the dielectric layer, an orthographic projection of an outer contour of the second opening on the substrate overlaps with an orthographic projection of the connecting electrode on the substrate, and an orthographic projection of the third opening on the substrate overlaps with an orthographic projection of a partial area of ​​the conductive portion on the substrate;

[0027] The first electrode is electrically connected to the connection electrode through the second opening, and the second electrode is electrically connected to the conductive portion through the third opening.

[0028] In some light-emitting devices provided in the embodiments of the present application, the light-emitting device further includes a bonding layer and a reflective layer;

[0029] The bonding layer is located on a side of the conductive portion away from the epitaxial structure and is electrically connected to the conductive portion; the reflective layer covers a side of the epitaxial structure, a side of the conductive portion, a side of the bonding layer and a surface of the epitaxial structure away from the substrate.

[0030] In a second aspect, an embodiment of the present application provides a light-emitting substrate, comprising a plurality of light-emitting devices and a driving substrate as described in any one of the first aspects.

[0031] In a third aspect, an embodiment of the present application provides a method for preparing a light-emitting device as described in any one of the first aspects, the method comprising:

[0032] forming an epitaxial thin film on a substrate;

[0033] Performing patterning on the epitaxial film to obtain a plurality of columnar structures and a groove between two adjacent columnar structures;

[0034] forming an insulating portion; the insulating portion is disposed in the groove, and the insulating portion covers at least a portion of the bottom of the groove and the sidewall of the groove;

[0035] A plurality of metal particles are formed; the plurality of metal particles are located on a surface of the insulating portion away from the substrate and are insulated from the epitaxial structure.

[0036] An embodiment of the present application provides a light-emitting device and a method for preparing the same, and a light-emitting substrate. The light-emitting device includes a substrate, an epitaxial structure located on one side of the substrate, a plurality of insulating parts, and a plurality of metal particles; a plurality of columnar structures are arranged on the epitaxial structure, and a groove is arranged between two adjacent columnar structures; the insulating part is arranged in the groove, and the insulating part covers the bottom of the groove and at least a portion of the side wall of the groove; the plurality of metal particles are located on the surface of the insulating part away from the substrate, and are insulated from the epitaxial structure.

[0037] The present application provides a structure of a light-emitting device, which can improve the internal quantum efficiency of the epitaxial structure by arranging a plurality of columnar structures in an epitaxial structure and arranging a groove between two adjacent columnar structures; the columnar structure and the groove of the epitaxial structure can also reduce the probability of total reflection, thereby improving the light extraction efficiency of the light-emitting device; in addition, an insulating portion is arranged to cover the bottom of the groove and at least a part of the side wall of the groove, a plurality of metal particles are arranged on the surface of the insulating portion away from the substrate, and the plurality of metal particles are insulated from the epitaxial structure, so that the metal particles can be excited by the luminophore of the epitaxial structure, providing an extremely high photon state density, which in turn enhances the spontaneous radiation rate of the epitaxial structure, further improving the light extraction efficiency of the light-emitting device.

[0038] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1-2 Structural schematic diagrams of two light-emitting devices provided in the embodiments of the present application;

[0041] Figure 3 A schematic diagram of an intermediate structure of a light emitting device provided in an embodiment of the present application;

[0042] Figure 4A to Figure 5The following are schematic structural diagrams of three light-emitting devices provided in the embodiments of the present application;

[0043] Figure 6 to Figure 18 A schematic diagram of an intermediate structure of a method for preparing a light-emitting device provided in an embodiment of the present application;

[0044] Figure 19 to Figure 22 A schematic diagram of an intermediate structure of another method for preparing a light-emitting device provided in an embodiment of the present application;

[0045] Figure 23 to Figure 26 A schematic diagram of an intermediate structure of another method for preparing a light-emitting device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] In the drawings, the thickness of regions and layers may be exaggerated for clarity. The same reference numerals in the drawings represent the same or similar structures, and thus their detailed descriptions will be omitted. In addition, the drawings are only schematic illustrations of the present application and are not necessarily drawn to scale.

[0048] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as an open, inclusive meaning, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" and the like are intended to indicate that specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present application. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics described may be included in any one or more embodiments or examples in any appropriate manner.

[0049] In the embodiments of the present application, words such as "first" and "second" are used to indicate parts of identical or similar items having substantially the same functions and effects. This is only for the purpose of clearly describing the technical solutions of the embodiments of the present application and shall not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0050] The features such as "parallel", "perpendicular" and "same" used in the embodiments of the present application include the features such as "parallel", "perpendicular", "same" in the strict sense, as well as the cases where "approximately parallel", "approximately perpendicular", "approximately the same" and the like contain certain errors, taking into account the errors associated with the measurement of the specific quantity (e.g., the limitations of the measurement system), and are expressed within the acceptable deviation range for the specific value determined by ordinary technicians in the field. For example, "approximately" can mean within one or more standard deviations, or within 10% or 5% of the value. "At least one" means one or more, and "a plurality" means at least two.

[0051] The "same layer" in the embodiments of the present application refers to the relationship between multiple film layers formed by the same material after the same step (e.g., a one-step patterning process). The "same layer" here does not always mean that the thickness of multiple film layers is the same or the height of multiple film layers in the cross-sectional view is the same. The polygons in this specification are not strictly defined, and can be approximate triangles, parallelograms, trapezoids, pentagons or hexagons, etc., and there may be some small deformations caused by tolerances.

[0052] In this specification, "electrically connected" and "coupled" include the situation where the components are connected together through an element having some electrical function. There is no particular limitation on the "element having some electrical function" as long as it can transmit and receive electrical signals between the connected components. Examples of "element having some electrical function" include not only electrodes and wiring, but also switching elements such as transistors, resistors, inductors, capacitors, and other elements having various functions.

[0053] With the rapid development of display technology, Mini LED (Mini Light Emitting Diode) and Micro LED (Micro Light Emitting Diode) display products have attracted widespread attention. However, in the related technologies, the light efficiency of these two types of display products is low and difficult to further improve.

[0054] Based on this, an embodiment of the present application provides a light-emitting device and a preparation method thereof, and a light-emitting substrate. The light-emitting device includes a substrate, an epitaxial structure located on one side of the substrate, multiple insulating parts and multiple metal particles; a plurality of columnar structures are arranged on the epitaxial structure, and a groove is arranged between two adjacent columnar structures; the insulating part is arranged in the groove, and the insulating part covers the bottom of the groove and at least a portion of the side wall of the groove; the multiple metal particles are located on the surface of the insulating part away from the substrate, and are insulated from the epitaxial structure.

[0055] The light-emitting device and its preparation method, and the light-emitting substrate provided in the embodiments of the present application will be specifically introduced and described below with reference to the accompanying drawings.

[0056] The embodiment of the present application provides a light emitting device, such as Figure 1 and Figure 2 As shown, the light emitting device comprises:

[0057] Substrate 1;

[0058] An epitaxial structure 2 is located on one side of the substrate 1; a plurality of columnar structures Z are arranged on the epitaxial structure 2, and a groove C is arranged between two adjacent columnar structures Z;

[0059] A plurality of insulating parts 4, wherein the insulating parts 4 are arranged in the groove C, and the insulating parts 4 cover at least a portion of the bottom CD of the groove C and the side wall CB of the groove C;

[0060] The plurality of metal particles 5 are located on a surface of the insulating portion 4 away from the substrate 1 , and the plurality of metal particles 5 are insulated from the epitaxial structure 2 .

[0061] The light emitting device provided in the embodiment of the present application may be a structure with a size reduced to the order of hundreds of microns. For example, the area of ​​the light emitting region of the light emitting device is preferably 1 mm 2 Below, more preferably 10000 μm 2 Below, more preferably 3000 μm 2 Below, more preferably 700 μm 2 Below, even below 200μm 2 the following.

[0062] Exemplarily, the light-emitting device may be a sub-millimeter light-emitting diode or a micro light-emitting diode that emits blue light; or, the light-emitting device may be a sub-millimeter light-emitting diode or a micro light-emitting diode that emits green light; or, the light-emitting device may be a sub-millimeter light-emitting diode or a micro light-emitting diode that emits red light.

[0063] There is no limitation on the specific material of the substrate 1. For example, the material of the substrate 1 may include one of glass, silicon, sapphire and polyimide.

[0064] In some embodiments, the light emitting device may not include the substrate 1. Specifically, the substrate 1 made of sapphire may be removed by laser lift-off; the substrate 1 made of silicon may be removed by wet etching or dry etching. Of course, in some embodiments, the light emitting device may include the substrate 1.

[0065] Exemplarily, the plane shape of the columnar structure Z can be circular, elliptical or polygonal, wherein the polygon includes a quadrilateral, a pentagon and a hexagon, as well as a rounded quadrilateral, a rounded pentagon and a rounded hexagon.

[0066] Exemplarily, the plane figure of the outer contour of the above-mentioned groove C can be a circle, an ellipse or a polygon, wherein the polygon includes a quadrilateral, a pentagon and a hexagon, as well as a rounded quadrilateral, a rounded pentagon and a rounded hexagon.

[0067] Exemplarily, the plane figure of the columnar structure Z and the plane figure of the outer contour of the groove C may be the same.

[0068] Exemplarily, the maximum size of the plane graph of the columnar structure Z is in the range of 300 nm to 1 μm.

[0069] Exemplarily, the maximum size of the planar figure of the outer contour of the groove C is in the range of 300 nm to 1 μm.

[0070] For example, Figure 1 or Figure 2 As shown, the epitaxial structure includes a first semiconductor layer 22 , a quantum well layer 23 (MQW) and a second semiconductor layer 24 which are sequentially arranged in a direction away from the substrate 1 .

[0071] In some examples, such as Figure 1 or Figure 2 As shown, the epitaxial structure may further include a buffer layer 21 .

[0072] The buffer layer 21 is used to improve the conduction stability between the first semiconductor layer 22 and the substrate 1 or the film forming property of the first semiconductor layer 22 on the substrate 1. Exemplarily, the material of the buffer layer 21 may include indium tin oxide (ITO).

[0073] The insulating portion 4 is used to isolate the metal particles 5 and the epitaxial structure 2 to prevent the two from overlapping and being electrically connected.

[0074] The insulating portion 4 covers at least a portion of the bottom CD of the groove C and the side wall CB of the groove C in the following cases:

[0075] The first type is that the insulating portion 4 covers the bottom CD of the groove C and covers a portion of the side wall CB of the groove C;

[0076] In the second type, the insulating portion 4 covers the bottom CD of the groove C and covers the entire area of ​​the side wall CB of the groove C.

[0077] The insulation arrangement between the plurality of metal particles 5 and the epitaxial structure 2 refers to that the plurality of metal particles 5 and the quantum well layer 23 in the epitaxial structure 2 are insulated from each other.

[0078] Regardless of whether the insulating portion 4 covers the entire area or a portion of the side wall CB of the groove C, the quantum well layer 23 in two adjacent columnar structures Z of the epitaxial structure 2 must be isolated from the metal particles 5 to prevent the metal particles 5 from conducting the quantum well layers 23 in the two adjacent columnar structures Z.

[0079] Exemplarily, the material of the insulating portion 4 includes an insulating material, such as resin.

[0080] Here, for the insulating portion 4

[0081] Exemplarily, the metal particles 5 may include at least one of gold (Au), silver (Ag), and copper (Cu).

[0082] Exemplarily, the size of the metal particles 5 along the normal direction of the substrate 1 ranges from 5 nm to 20 nm.

[0083] Exemplary metal particles 5 have a size in the normal direction perpendicular to substrate 1 ranging from 50 nm to 200 nm, for example, 80 nm, 100 nm, 120 nm, 150 nm, 170 nm, 180 nm or 190 nm.

[0084] The sizes of the metal particles 5 mentioned above all refer to the average size of the plurality of metal particles 5 , and the size of a single metal particle 5 may fluctuate by 3% to 5% based on the average size.

[0085] The above-mentioned metal particles 5 can also be called surface plasmons (SP). Surface plasmons (SP) are electromagnetic modes formed by the interaction of free electrons and photons in the interface region between metals and dielectrics. This concept was first proposed by Huffman et al. in 1957. He believed that after free electrons in metals are excited by an external electromagnetic field, they will oscillate in a quantized manner against the background of positive ions. Under certain conditions, surface plasmons (SP) are excited by the surrounding luminophores, and at the same time, they excite very strong near-field electromagnetic fields and provide extremely high photon state density, which in turn can enhance the spontaneous radiation rate of the luminophore.

[0086] The present application provides a structure of a light-emitting device, which is provided by arranging a plurality of columnar structures Z in an epitaxial structure, and a groove C is provided between two adjacent columnar structures Z, so that a whole epitaxial structure 2 light-emitting body is divided into light-emitting bodies of a plurality of columnar structures Z by the groove C, which can weaken the polarization electric field and improve the internal quantum efficiency of the epitaxial structure; the columnar structures Z and the grooves C of the epitaxial structure 2 can also reduce the probability of total reflection of the light-emitting device, thereby improving the light extraction efficiency of the light-emitting device; in addition, an insulating part 4 is provided to cover at least a part of the bottom CD of the groove C and the side wall CB of the groove C, a plurality of metal particles 5 are provided on the surface of the insulating part 4 away from the substrate 1, and the plurality of metal particles 5 are insulated from the epitaxial structure 2, so that the metal particles 5 can be excited by the light-emitting body of the epitaxial structure 2, and provide an extremely high photon state density, which in turn enhances the spontaneous radiation rate of the epitaxial structure 2, and further improves the light extraction efficiency of the light-emitting device.

[0087] In some light-emitting devices provided in the embodiments of the present application, such as Figure 1 and Figure 2 As shown, the epitaxial structure 2 includes a buffer layer 21, a first semiconductor layer 22, a quantum well layer 23 and a second semiconductor layer 24 which are sequentially arranged in a direction away from the substrate 1;

[0088] Exemplarily, the first semiconductor layer 22 may be a P-type semiconductor layer, such as P-type gallium nitride (P-GaN), and the second semiconductor layer 24 may be an N-type semiconductor layer, such as N-type gallium nitride (N-GaN). Alternatively, the first semiconductor layer 22 may be an N-type semiconductor layer, such as N-type gallium nitride (N-GaN), and the second semiconductor layer 24 may be a P-type semiconductor layer, such as P-type gallium nitride (P-GaN).

[0089] Among them, Figure 3 As shown, an average distance d2 between the surface of the insulating portion 4 away from the substrate 1 and the substrate 1 is greater than an average distance d1 between the surface of the quantum well layer 23 away from the substrate 1 and the substrate 1 . Figure 3 for Figure 1 and Figure 2 A simplified schematic diagram is provided to clearly mark the positions of d1 and d2.

[0090] It should be noted that the average distance d2 between the surface of the insulating portion 4 away from the substrate 1 and the substrate 1 refers to the average value between the maximum distance d4 between the surface of the insulating portion 4 away from the substrate 1 and the substrate 1 and the minimum distance d3 between the surface of the insulating portion 4 away from the substrate 1 and the substrate 1.

[0091] There is no limitation on whether the surface of the insulating portion 4 away from the substrate 1 is a flat surface or a curved surface. This specification takes the surface away from the substrate 1 as a curved surface as an example for drawing and explanation.

[0092] In the embodiment of the present application, the average distance d2 between the surface of the insulating portion 4 away from the substrate 1 and the substrate 1 is set to be greater than the average distance d1 between the surface of the quantum well layer 23 away from the substrate 1 and the substrate 1. In this way, when the plurality of metal particles 5 are arranged on the surface of the insulating portion 4 away from the substrate 1, the plurality of metal particles 5 and the quantum well layer 23 must not be in contact, that is, the two are insulated and cannot be conductive.

[0093] In some light-emitting devices provided in the embodiments of the present application, such as Figure 1 or Figure 2 As shown, the bottom CD of the groove C includes a partial area of ​​the first semiconductor layer 22;

[0094] Among them, Figure 2 As shown, the columnar structure Z includes a partial region of the first semiconductor layer 22, a partial region of the quantum well layer 23, and a partial region of the second semiconductor layer 24, which are sequentially arranged in a direction away from the substrate 1; the side surfaces of the first semiconductor layer 22, the side surfaces of the quantum well layer 23, and the side surfaces of the second semiconductor layer 24 in the columnar structure Z serve as side walls CB of the groove C.

[0095] Or, if Figure 1 As shown, the columnar structure Z includes a partial area of ​​the quantum well layer 23 and a partial area of ​​the second semiconductor layer 24 arranged in sequence along a direction away from the substrate 1; the side surfaces of the quantum well layer 23 and the second semiconductor layer 24 in the columnar structure Z serve as side walls CB of the groove C.

[0096] In some light-emitting devices provided in the embodiments of the present application, such as Figure 2 As shown, the columnar structure Z further includes a first conductive portion 31 , which is located on a side of a partial region of the second semiconductor layer 24 away from the substrate 1 ; the side surface of the first conductive portion layer 31 in the columnar structure Z serves as a side wall of the groove C.

[0097] In some light-emitting devices provided in the embodiments of the present application, such as Figures 1 to 5 As shown, the insulating portion 4 at least covers the side surfaces of the quantum well layer 23 in the side walls of the groove C.

[0098] In an exemplary embodiment, the insulating portion 4 covers the side surfaces of the quantum well layer 23 in the side walls of the groove C; or, the insulating portion 4 covers the side surfaces of the quantum well layer 23 and the side surfaces of the second semiconductor layer 24 in the side walls of the groove C; or, the insulating portion 4 covers the side surfaces of the first semiconductor layer 22 and the side surfaces of the quantum well layer 23 in the side walls of the groove C; or, the insulating portion 4 covers the side surfaces of the first semiconductor layer 22, the side surfaces of the quantum well layer 23, and the side surfaces of the second semiconductor layer 24 in the side walls of the groove C; or, the insulating portion 4 covers the side surfaces of the first semiconductor layer 22, the side surfaces of the quantum well layer 23, the side surfaces of the second semiconductor layer 24, and the side surfaces of the first conductive portion layer 31 in the side walls of the groove C.

[0099] In some light-emitting devices provided in embodiments of the present application, the light-emitting device further includes a passivation layer (not drawn), which covers the bottom CD of the groove C and the side wall of the groove CB; wherein the insulating part 4 is located on the side of the passivation layer away from the bottom CD of the groove C and the side wall CB of the groove C.

[0100] The passivation layer is located between the groove C and the insulating portion 4 , and is used to protect the sidewall CB and the bottom CD of the groove C.

[0101] Exemplarily, the passivation layer refers to SiO, SiN, Al2O3, etc. used to protect the sidewalls and bottom of the groove C, wherein SiO can be formed by ALD, PECVD, etc., and SiO formed by curing an organic passivation glue can also be used as the passivation layer.

[0102] In some embodiments, the sidewall of the groove C may be repaired by high temperature annealing or wet etching without setting a passivation layer (mainly for repairing the epitaxial structure); wherein, high temperature annealing refers to annealing at a certain temperature (500-900°C) in an atmosphere such as N2 or NH3 to reduce internal dislocations of the epitaxial structure, while promoting local element diffusion and recombination to reduce internal defects (changes at the atomic level, changes that cannot be seen); in addition, wet etching refers to using alkaline KOH, TMAH or acidic H3PO4 solutions to react with the sidewalls to reduce the surface dangling bonds and oxide content, thereby reducing defects; in addition, neutral solutions such as ammonium sulfide may be used to replace the surface to reduce the defect content. It should be noted that after wet etching, an uneven structure will appear on the sidewall surface.

[0103] In some light-emitting devices provided in the embodiments of the present application, such as Figure 5 As shown, the light emitting device further includes a color conversion portion QD;

[0104] The color conversion part QD is located in the region between the insulating part 4 and the metal particles 5;

[0105] Alternatively, the color conversion portion QD and the insulating portion 4 are an integrated structure.

[0106] in, Figure 5 In the figure, the color conversion part QD and the insulating part 4 are drawn as an integrated structure as an example.

[0107] Exemplarily, the color conversion portion QD includes a quantum dot material, for example, a red quantum dot material or a green quantum dot material. In this case, the luminescent color of the epitaxial structure 2 may be blue.

[0108] In the case where the color conversion portion QD and the insulating portion 4 are an integrated structure, the material of the color conversion portion QD can be mixed with the material of the insulating portion 4 and then prepared by methods such as gluing and curing.

[0109] In the embodiments of the present application, the light-emitting device further includes a color conversion unit QD; the color conversion unit QD is located in the region between the insulating unit 4 and the metal particles 5; or the color conversion unit QD and the insulating unit 4 are an integrated structure; thus, when the light-emitting device emits light, the metal particles 5 can enhance the radiation rate of the color conversion unit QD and improve the color conversion efficiency. In some examples, when the metal particles 5 (plasmons) are provided, the spontaneous radiation rate of the color conversion unit QD can be increased by nearly 1000 times by enhancing the light emission through the plasmons.

[0110] In some light-emitting devices provided in the embodiments of the present application, such as Figures 2 to 5 As shown, the light emitting device further includes a second conductive portion 32 , which covers the plurality of columnar structures Z, the plurality of metal particles 5 and the gaps between the metal particles 5 , and electrically connects the metal particles 5 in the plurality of grooves C together.

[0111] The first conductive part 31 and the second conductive part 32 are stacked together and are called the conductive part 3 .

[0112] In some light-emitting devices provided in the embodiments of the present application, such as Figures 1 to 5 Shown (for clarity only Figure 5 The thickness H1 of the conductive part 3 located on the columnar structure Z along the normal direction of the substrate 1 is greater than the thickness H2 of the conductive part 3 located in the groove C along the normal direction of the substrate 1. The conductive part 3 includes a first conductive part 31 and a second conductive part 32.

[0113] In some light-emitting devices provided in the embodiments of the present application, Figure 4A and Fig.19 As shown, the light-emitting device further includes a connecting electrode L, a first electrode DJ1 and a second electrode DJ2. A first opening K1 is provided on the epitaxial structure 2 and the conductive portion 3. The orthographic projection of the outer contour of the first opening K1 on the substrate 1 partially overlaps with the orthographic projection of the first semiconductor layer 22 of the epitaxial structure on the substrate 1; the connecting electrode L is electrically connected to the first semiconductor layer 22 through the first opening K1; the light-emitting device further includes a dielectric layer J, which covers a portion of the conductive portion 3 and the connecting electrode L, and is combined with Figure 4A and Fig.21 As shown, a second opening K2 and a third opening K3 are provided on the dielectric layer J, the orthographic projection of the outer contour of the second opening K2 on the substrate 1 overlaps with the orthographic projection of the connecting electrode L on the substrate 1, and the orthographic projection of the third opening K3 on the substrate 1 overlaps with the orthographic projection of a partial area of ​​the conductive portion 3 on the substrate 1;

[0114] like Figure 4AAs shown, the first electrode DJ1 is electrically connected to the connection electrode L through the second opening K2, and the second electrode DJ2 is electrically connected to the conductive portion 3 through the third opening K3.

[0115] One of the first electrode DJ1 and the second electrode DJ2 is an anode, and the other is a cathode.

[0116] In some light-emitting devices provided in the embodiments of the present application, such as Figure 4B As shown, the light-emitting device also includes a bonding layer JH and a reflective layer F; the bonding layer JH is located on the side of the conductive part 3 away from the epitaxial structure 2, and is electrically connected to the conductive part 3; the reflective layer F covers the side of the epitaxial structure 2, the side of the conductive part 3, the side of the bonding layer JH, and the surface of the epitaxial structure 2 away from the substrate 1.

[0117] Figure 4B A schematic diagram of a structure in which a plurality of light emitting devices are arranged on a driving substrate BP is drawn, wherein: Figure 4B The dotted box in FIG. 1 is one of the light emitting devices. In addition, it should be noted that: Figure 1 , Figure 2 and Figure 4A A light-emitting device is drawn in each case.

[0118] Exemplarily, the bonding layer JH fixes and connects the epitaxial structure and the conductive structure together through bonding.

[0119] The reflective layer F is used to reflect light and improve the light extraction efficiency of the light emitting device.

[0120] The specific material of the reflective layer F is not limited here, and any material with a reflective effect can be used to prepare the reflective layer F. Exemplarily, the material of the reflective layer F may include metal, such as silver (Ag), aluminum (Al), and copper (Cu). Exemplarily, the material of the reflective layer F may include a reflective film and a reflective coating; wherein the reflective film may achieve a reflective effect by forming an uneven microstructure on the surface of the film layer; and the reflective coating may include a polymer reflective material.

[0121] An embodiment of the present application provides a light-emitting substrate, which includes a plurality of light-emitting devices as described in any one of the above, and also includes a driving substrate.

[0122] In some examples, the above-mentioned light-emitting substrate can be directly used for backlight, for example, the light-emitting colors of multiple light-emitting devices in the light-emitting substrate are the same, and are all white; or the light-emitting colors of multiple light-emitting devices in the light-emitting substrate are the same, and are all blue.

[0123] In some examples, the light-emitting substrate can be directly used for display. For example, the light-emitting devices in the light-emitting substrate have different light-emitting colors. For example, the light-emitting substrate includes three light-emitting devices with red, green and blue light-emitting colors.

[0124] In some examples, the light emitting device may not include the substrate 1. Specifically, the substrate 1 made of sapphire may be removed by laser stripping; the substrate 1 made of silicon may be removed by wet etching or dry etching. Figure 4B , wherein the bonding layer JH electrically connects the driving substrate BP and the plurality of light-emitting devices together, and then an electrode 6 (eg, a cathode) is disposed on a side of the epitaxial structure 2 away from the driving substrate BP.

[0125] An embodiment of the present application provides a method for preparing a light-emitting device as described in any one of the foregoing, the method comprising:

[0126] S01, such as Figure 6 As shown, an epitaxial thin film is formed on a substrate 1;

[0127] S02, such as Fig.11 As shown, the epitaxial film is patterned to obtain a plurality of columnar structures Z and a groove C located between two adjacent columnar structures Z;

[0128] S03, such as Fig.14 As shown, an insulating portion 4 is formed; the insulating portion 4 is disposed in the groove C, and the insulating portion 4 covers at least a portion of the bottom CD of the groove C and the side wall CB of the groove C;

[0129] S04, such as Fig.17 As shown, a plurality of metal particles 5 are formed; the plurality of metal particles 5 are located on a surface of the insulating portion 4 away from the substrate 1 and are insulated from the epitaxial structure 2 .

[0130] The light-emitting device prepared in the present application is provided with a plurality of columnar structures Z in the epitaxial structure, and a groove C is provided between two adjacent columnar structures Z. Thus, the light-emitting body of an integral epitaxial structure 2 is divided into light-emitting bodies of a plurality of columnar structures Z by the groove C, so that the polarization electric field can be weakened and the internal quantum efficiency of the epitaxial structure can be improved. The columnar structures Z and the grooves C of the epitaxial structure 2 can also reduce the probability of total reflection of the light-emitting device, thereby improving the light extraction efficiency of the light-emitting device. In addition, an insulating portion 4 is provided to cover at least a portion of the bottom CD of the groove C and the side wall CB of the groove C, a plurality of metal particles 5 are provided on the surface of the insulating portion 4 away from the substrate 1, and the plurality of metal particles 5 are insulated from the epitaxial structure 2. Thus, the metal particles 5 can be excited by the light-emitting body of the epitaxial structure 2, providing an extremely high photon state density, thereby in turn enhancing the spontaneous radiation rate of the epitaxial structure 2, and further improving the light extraction efficiency of the light-emitting device.

[0131] It should be noted that in this specification, “layer” refers to the structure after patterning, and “film” refers to the structure before patterning.

[0132] Below Figure 2 Taking the structure shown in the figure as an example, a method for preparing a light-emitting device is described as follows:

[0133] Step 1: Figure 6 As shown, an epitaxial film is formed on a substrate 1 (the epitaxial film is an epitaxial structure 2 before patterning. In order to avoid confusion, Figure 6 The epitaxial film is also marked as 2);

[0134] Step 2: Figure 6 As shown, a first conductive film 30 is formed on the epitaxial film;

[0135] The thickness of the first conductive portion thin film 30 is about 120 nm, for example, 120 nm±10 nm.

[0136] Step 3: Figure 7 As shown, a hard mask film SiO is formed on the first conductive film 30, wherein the hard mask film may be one of silicon oxide, silicon nitride or silicon oxynitride. This specification takes the case where the hard mask film may be silicon oxide as an example for explanation;

[0137] The thickness of the hard mask film SiO ranges from 100nm to 400nm.

[0138] Step 4: Figure 8 As shown, a first imprint mask pattern PR1 is formed on the hard mask film SiO, as shown Fig. 9 As shown, the first imprint mask pattern PR1 is used as a mask plate to perform patterning to obtain a hard mask pattern SiO;

[0139] Among them, nanoimprinting and etching can be selected for patterning according to size requirements (patterning size ≥ 100 nm), or exposure and development processes can be selected for patterning (patterning size ≥ 500 nm).

[0140] After the nano-imprinting, F-based gas, such as CF4, SF6, CHF3, etc., may be used to etch the hard mask film SiO to ensure that the hard mask film SiO is completely etched.

[0141] Step 5: Fig.10 As shown, the first conductive portion thin film 30 is patterned to obtain the first conductive portion 30;

[0142] Among them, a mixture of Cl2 / BCl3 / Ar or the like can be used to etch the first conductive portion film 3.

[0143] The material of the first conductive film 3 is indium tin oxide (ITO).

[0144] Step 6: Fig.11 As shown, the epitaxial film is patterned to obtain an epitaxial structure 2, wherein the epitaxial structure 2 includes a plurality of columnar structures Z and a groove C located between two adjacent columnar structures Z;

[0145] Among them, a mixed gas such as Cl2 / BCl3 can be used to etch the epitaxial thin film to simultaneously obtain the columnar structure Z and the groove C. For example, P-GaN, MQW, and N-GaN are sequentially etched (N-GaN is not etched; or N-GaN is partially etched but not etched through), and the etching depth of the epitaxial thin film is about 300nm~1um.

[0146] Step 7: Fig.12 As shown, the first imprint mask pattern PR1 is removed;

[0147] Exemplarily, the first imprint mask pattern PR1 may be a nanoimprint paste.

[0148] Step 8, perform defect repair; in the previous patterning process, the side wall of the groove C will be damaged, which can be repaired by high temperature annealing, wet etching, side wall passivation, etc.

[0149] In some light-emitting devices, the light-emitting device further includes a passivation layer (not shown), and the passivation layer covers the bottom CD of the groove C and the side wall of the groove CB; wherein the insulating portion 4 is located on a side of the passivation layer away from the bottom CD of the groove C and the side wall CB of the groove C. The passivation layer is between the groove C and the insulating portion 4, and is used to protect the side wall CB and the bottom CD of the groove C.

[0150] Exemplarily, the passivation layer refers to SiO, SiN, Al2O3, etc. used to protect the sidewalls and bottom of the groove C, wherein the passivation layer can be formed by ALD, PECVD, etc., and SiO formed by curing an organic passivation glue can also be used as the passivation layer.

[0151] In some embodiments, the sidewall of the groove C may be repaired by high temperature annealing or wet etching without setting a passivation layer (mainly for repairing the epitaxial structure); wherein, high temperature annealing refers to annealing at a certain temperature (500-900°C) in an atmosphere such as N2 or NH3 to reduce internal dislocations of the epitaxial structure, while promoting local element diffusion and recombination to reduce internal defects (changes at the atomic level, changes that cannot be seen); in addition, wet etching refers to using alkaline KOH, TMAH or acidic H3PO4 solutions to react with the sidewalls to reduce the surface dangling bonds and oxide content, thereby reducing defects; in addition, neutral solutions such as ammonium sulfide may be used to replace the surface to reduce the defect content. It should be noted that after wet etching, an uneven structure will appear on the sidewall surface.

[0152] Step 9: Fig.13 As shown, an insulating material 40 is applied; wherein the insulating material 40 fills the groove C and covers the surface of the columnar structure Z;

[0153] Insulating material can be spin coated (for example, Spin on glass process, referred to as SOG); after the insulating material is solidified, a polymer is formed, and the main component of the polymer is SiO. In this way, on the one hand, the quantum well layers in two adjacent columnar structures Z can be prevented from being turned on, and on the other hand, the side walls of the columnar structure Z can be protected to reduce the defects of the epitaxial structure after etching.

[0154] Step 10: Fig.14 As shown, the insulating material 40 is etched on the entire surface to remove the insulating material 40 on the surface of the columnar structure Z, and the insulating material 40 in a part of the groove C is etched away to obtain the insulating portion 4;

[0155] Step 11: Fig.15 As shown, Ag film is plated with a thickness of 5-20nm;

[0156] Step 12: Fig.16 As shown, the annealing method is adopted, the temperature is 400-600℃, the time is 5-20min, and different film thicknesses and annealing conditions can form different Ag nanoparticle sizes;

[0157] Alternatively, step 11 and step 12 may be replaced by spin coating the entire surface with a suspension of Ag nanoparticles.

[0158] Step 13: Fig.17 As shown, the hard mask pattern SiO on the columnar structure Z is removed;

[0159] The hard mask pattern SiO on the columnar structure Z can be removed by wet etching, HF solution immersion, ultrasonic treatment, etc. At the same time, the Ag particles attached to the hard mask pattern SiO will also be cleaned away, leaving only the Ag particles in the groove C.

[0160] Step 14: Fig.18 As shown, the entire surface of ITO is deposited as the second conductive portion 32. To ensure good current spreading performance, the thickness of ITO is preferably greater than or equal to 100 nm and less than and equal to 300 nm.

[0161] Below Figure 4A Taking the structure shown in FIG. 1 as an example, the preparation method of the light emitting device is further described as follows:

[0162] Step 15: Fig.19 As shown, the first opening K1 is etched; specifically, the conductive portion 3 is etched first, and then the epitaxial structure is etched;

[0163] The epitaxial structure 2 may be etched through the quantum well layer 23 ; or, the epitaxial structure 2 may be etched through the quantum well layer 23 and a portion of the thickness of the first semiconductor layer 22 may be etched.

[0164] Step 16: Fig. 20 As shown, a connecting electrode L is formed;

[0165] The connecting electrode L can be deposited by E-beam electron beam evaporation and can be a stacked structure of Ti / Al / Ni / Au with a thickness of 30 / 175 / 35 / 1000nm; or a stacked structure of Cr / Pt / Au with a thickness of 20nm / 20nm / 1000nm.

[0166] Step 17: Fig.21 As shown, a dielectric layer J is formed, and a second opening K2 and a third opening K3 are provided on the dielectric layer J. The orthographic projection of the outer contour of the second opening K2 on the substrate 1 overlaps with the orthographic projection of the connecting electrode L on the substrate 1, and the orthographic projection of the third opening K3 on the substrate 1 overlaps with the orthographic projection of a partial area of ​​the conductive portion 3 on the substrate 1;

[0167] The dielectric layer J has a thickness ranging from 600 nm to 700 nm, and the material of the dielectric layer may be an inorganic insulating material, such as one of silicon nitride, silicon oxide and silicon oxynitride.

[0168] Step 18: Fig. 22 As shown, a first electrode DJ1 and a second electrode DJ2 are formed;

[0169] The first electrode DJ1 and the second electrode DJ2 may both adopt a stacked structure of Ti / Al / Ni / Au or Cr / Pt / Au, with an overall thickness of about 1.5 μm.

[0170] Step 19: Combine Figure 4AAs shown by the arrows at both ends, deep etching is performed with an etching depth of 4-5 μm to separate the multiple light-emitting devices and to etch to the sapphire substrate 1 to facilitate the subsequent cutting process to cut the multiple light-emitting devices apart.

[0171] It should be noted that Figure 19 to Figure 22 A light-emitting device is drawn in each of the figures.

[0172] Below Figure 4B Taking the structure shown in FIG. 1 as an example, a method for preparing a light-emitting substrate for preparing a light-emitting device is further described as follows:

[0173] Step 15: Fig.23 As shown, a bonding layer JH is formed on the side of the conductive portion 3 away from the epitaxial structure 2;

[0174] The bonding layer JH metal uses MTD / Cu or Au, etc. MTD / Cu is prepared by Sputter, and Au can be evaporated by E-beam with a thickness of 1 to 2 μm. MTD is a molybdenum-copper alloy.

[0175] Step 16: Fig.24 As shown, the light emitting device is patterned; Fig.24 The dotted frame is a light emitting device; Figure 23 to Figure 26 In the figure, for the sake of clarity, a light emitting device is drawn including two columnar structures. In practical applications, a light emitting device includes a plurality of columnar structures arranged in an array;

[0176] It should be noted that when forming the bonding layer JH, the epitaxial structures of multiple light-emitting devices are connected together. After the bonding layer JH is formed, the epitaxial structures of the multiple light-emitting devices are patterned to separate the epitaxial structures of two adjacent light-emitting devices; in practice, the epitaxial structures of multiple light-emitting devices are connected as a whole through the same substrate 1.

[0177] Patterning specifically includes photoresist coating, exposure and development, and etching. Etching is performed in steps, metal materials can be dry etched, and epitaxial structures can be etched by gas, and etching gases generally include Cl2 and BCl3.

[0178] Step 17: Fig.24 As shown, a reflective portion F is deposited on the side wall of the light emitting device, wherein the reflective portion F is made of a high reflectivity metal such as Ag or Al, with a thickness of about 100 nm, and is patterned and etched at the same time to expose the top bonding layer JH;

[0179] Step 18: Fig.25As shown, the cut light-emitting device array and the driving substrate BP (such as a silicon-based backplane) are bonded with high precision to achieve electrical connection between the driving substrate and the light-emitting device; the bonding metal 7 is bonded to the bonding layer JH, and the bonding metal 7 can be gold (Au) or tin (Sn).

[0180] Step 19: Fig.26 As shown, the substrate 1 and the buffer layer 21 in the epitaxial structure are removed;

[0181] Step 20: Fig.26 As shown, an electrode 6 (eg, a cathode) is prepared on a side of the epitaxial structure 2 away from the driving substrate BP.

[0182] The material of the electrode 6 can be a stacked Ti / Al / Ni / Au or a stacked Cr / Pt / Au, the thickness range of Ti / Al / Ni / Au is 15nm~30nm / 50nm~200nm / 20nm~50nm / 50nm~350nm; the thickness of Cr / Pt / Au is 50nm±5nm / 20nm±5nm / 250nm±5nm.

[0183] This specification only introduces the structure and preparation process related to the invention point of the light-emitting device. The light-emitting device may also include other film layers and structures, and the preparation method may also include other processes and steps. For details, please refer to the introduction in the relevant technology, which will not be repeated here.

[0184] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A light emitting device, characterized in that: The light emitting device comprises: substrate; An epitaxial structure located on one side of the substrate; a plurality of columnar structures are arranged on the epitaxial structure, and a groove is arranged between two adjacent columnar structures; A plurality of insulating parts, wherein the insulating parts are arranged in the groove and cover at least a portion of the bottom of the groove and the sidewall of the groove; A plurality of metal particles are located on a surface of the insulating portion away from the substrate, and the plurality of metal particles are insulated from the epitaxial structure.

2. The light emitting device according to claim 1, characterized in that: The epitaxial structure comprises a buffer layer, a first semiconductor layer, a quantum well layer and a second semiconductor layer which are sequentially arranged in a direction away from the substrate; The average distance between the surface of the insulating portion away from the substrate and the substrate is greater than the average distance between the surface of the quantum well layer away from the substrate and the substrate.

3. The light emitting device according to claim 2, characterized in that: The bottom of the groove includes a partial area of ​​the first semiconductor layer; The columnar structure includes a partial region of the first semiconductor layer, a partial region of the quantum well layer, and a partial region of the second semiconductor layer, which are sequentially arranged in a direction away from the substrate; a side surface of the first semiconductor layer, a side surface of the quantum well layer, and a side surface of the second semiconductor layer in the columnar structure serve as a side wall of the groove, Alternatively, the columnar structure includes a partial region of the quantum well layer and a partial region of the second semiconductor layer arranged in sequence along a direction away from the substrate; the side surfaces of the quantum well layer and the side surfaces of the second semiconductor layer in the columnar structure serve as side walls of the groove.

4. The light emitting device according to claim 3, characterized in that: The columnar structure further includes a first conductive portion, and the first conductive portion is located on a side of a partial region of the second semiconductor layer away from the substrate; The side surface of the first conductive layer in the columnar structure serves as the side wall of the groove.

5. The light emitting device according to claim 3 or 4, characterized in that: The insulating portion at least covers a side surface of the quantum well layer in a side wall of the groove.

6. The light emitting device according to claim 5, characterized in that: The light emitting device further comprises a passivation layer, wherein the passivation layer covers the bottom of the groove and the sidewall of the groove; The insulating portion is located on a side of the passivation layer away from the bottom of the groove and the sidewall of the groove.

7. The light emitting device according to claim 1, characterized in that: The light emitting device further includes a color conversion portion; The color conversion portion is located in a region between the insulating portion and the metal particles; Alternatively, the color conversion portion and the insulating portion are an integrated structure.

8. The light emitting device according to any one of claims 1 to 7, characterized in that: The light emitting device further includes a second conductive portion, which covers the plurality of columnar structures, the plurality of metal particles and gaps between the metal particles, and electrically connects the metal particles in the plurality of grooves together.

9. The light emitting device according to claim 8, characterized in that: The light emitting device further comprises a connecting electrode, a first electrode and a second electrode, a first opening is provided on the epitaxial structure and the conductive part, and an orthographic projection of an outer contour of the first opening on the substrate partially overlaps with an orthographic projection of a first semiconductor layer of the epitaxial structure on the substrate; the conductive part comprises a first conductive part and a second conductive part; The connecting electrode is electrically connected to the first semiconductor layer through the first opening; The light emitting device further comprises a dielectric layer, the dielectric layer covers the conductive portion and a partial area of ​​the connecting electrode, a second opening and a third opening are provided on the dielectric layer, an orthographic projection of an outer contour of the second opening on the substrate overlaps with an orthographic projection of the connecting electrode on the substrate, and an orthographic projection of the third opening on the substrate overlaps with an orthographic projection of a partial area of ​​the conductive portion on the substrate; The first electrode is electrically connected to the connection electrode through the second opening, and the second electrode is electrically connected to the conductive portion through the third opening.

10. The light emitting device according to claim 8, characterized in that: The light emitting device further comprises a bonding layer and a reflective layer; The bonding layer is located on a side of the conductive portion away from the epitaxial structure and is electrically connected to the conductive portion; the reflective layer covers a side of the epitaxial structure, a side of the conductive portion, a side of the bonding layer and a surface of the epitaxial structure away from the substrate.

11. A light-emitting substrate, comprising a plurality of light-emitting devices according to any one of claims 1 to 10 and a driving substrate.

12. A method for preparing a light emitting device according to any one of claims 1 to 10, characterized in that: The method comprises: forming an epitaxial thin film on a substrate; Performing patterning on the epitaxial film to obtain a plurality of columnar structures and a groove between two adjacent columnar structures; forming an insulating portion; the insulating portion is disposed in the groove, and the insulating portion covers at least a portion of the bottom of the groove and the sidewall of the groove; A plurality of metal particles are formed; the plurality of metal particles are located on a surface of the insulating portion away from the substrate and are insulated from the epitaxial structure.

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