Miniature light-emitting element and miniature light-emitting element structure

Abstract

The invention provides a micro light-emitting element and a micro light-emitting element structure. The micro light-emitting element comprises an epitaxial structure, a first electrode, a second electrode, a first contact layer and a diffusion structure. The epitaxial structure comprises a first type semiconductor layer, an active layer and a second type semiconductor layer which are stacked in sequence. The second type semiconductor layer has an outer surface relatively away from the first type semiconductor layer. The first and second electrodes are respectively disposed on the epitaxial structure and electrically connected to the first and second type semiconductor layers, respectively. The first contact layer is disposed between the first electrode and the first type semiconductor layer. The diffusion structure is disposed on a side of the second type semiconductor layer away from the first type semiconductor layer. The conductivity of the diffusion structure is smaller than that of the second type semiconductor layer. The outer surface of the second-type semiconductor layer exposes the lower surface of the diffusion structure away from the first-type semiconductor layer. According to the micro light-emitting element, the uniformity of the current density can be improved, so that the internal quantum efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a semiconductor element and a semiconductor structure, and in particular to a micro light-emitting element and a micro light-emitting element structure. Background Art

[0002] The luminous efficiency of a micro-LED chip is related to its internal quantum efficiency and external light extraction efficiency, wherein the internal quantum efficiency of a micro-LED chip is related to its epitaxial quality and electrode design. Generally speaking, when the current enters the micro-LED chip through the contact layer, it has already passed through the active layer before diffusing in the horizontal direction, and most of the carriers are recombined just below the connection between the contact layer and the semiconductor layer, resulting in a high local current density and low internal quantum efficiency. Summary of the invention

[0003] The present invention is directed to a micro-light emitting element, which can increase the uniformity of current density to improve internal quantum efficiency.

[0004] The present invention is also directed to a micro-light emitting element structure, which includes the above-mentioned micro-light emitting element and has better display quality.

[0005] According to an embodiment of the present invention, a micro-light-emitting element includes an epitaxial structure, a first electrode, a second electrode, a first contact layer and a diffusion structure. The epitaxial structure includes a first-type semiconductor layer, an active layer and a second-type semiconductor layer stacked in sequence. The second-type semiconductor layer has an outer surface relatively far away from the first-type semiconductor layer. The first electrode is configured on the epitaxial structure and electrically connected to the first-type semiconductor layer. The second electrode is configured on the epitaxial structure and electrically connected to the second-type semiconductor layer. The first contact layer is configured between the first electrode and the first-type semiconductor layer. The diffusion structure is configured on a side of the second-type semiconductor layer away from the first-type semiconductor layer. The conductivity of the diffusion structure is less than the conductivity of the second-type semiconductor layer. The outer surface of the second-type semiconductor layer exposes the lower surface of the diffusion structure away from the first-type semiconductor layer.

[0006] According to an embodiment of the present invention, a micro-light-emitting element structure includes a substrate and a plurality of micro-light-emitting elements. The micro-light-emitting elements are separately arranged on the substrate. Each micro-light-emitting element includes an epitaxial structure, a first electrode, a second electrode, a first contact layer and a diffusion structure. The epitaxial structure includes a first-type semiconductor layer, an active layer and a second-type semiconductor layer stacked in sequence. The second-type semiconductor layer has an outer surface relatively far away from the first-type semiconductor layer. The first electrode is arranged on the epitaxial structure and electrically connected to the first-type semiconductor layer. The second electrode is arranged on the epitaxial structure and electrically connected to the second-type semiconductor layer. The first contact layer is arranged between the first electrode and the first-type semiconductor layer. The diffusion structure is arranged on a side of the second-type semiconductor layer away from the first-type semiconductor layer. The conductivity of the diffusion structure is less than the conductivity of the second-type semiconductor layer. The outer surface of the second-type semiconductor layer exposes the lower surface of the diffusion structure away from the first-type semiconductor layer.

[0007] Based on the above, in the design of the micro-light-emitting device of the present invention, the diffusion structure is disposed on the side of the second-type semiconductor layer away from the first-type semiconductor layer, wherein the conductivity of the diffusion structure is less than the conductivity of the second-type semiconductor layer, and the outer surface of the second-type semiconductor layer exposes the lower surface of the diffusion structure away from the first-type semiconductor layer. Through the design of the diffusion structure, carriers can be effectively blocked from flowing directly to the original recombination area, forcing the current to be diffused to a larger range, thereby increasing the uniformity of the current density to improve the internal quantum efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A is a cross-sectional schematic diagram of a micro-light emitting element according to an embodiment of the present invention;

[0009] Figure 1B yes Figure 1A A schematic top view of a micro light-emitting element;

[0010] Figure 1C is a schematic top view of a micro light emitting element according to another embodiment of the present invention;

[0011] Figure 2A is a cross-sectional schematic diagram of a micro-light emitting element according to another embodiment of the present invention;

[0012] Figure 2B yes Figure 2A A schematic top view of a micro light-emitting element;

[0013] Figure 2C is a schematic top view of a micro light emitting element according to another embodiment of the present invention;

[0014] Figure 3A is a cross-sectional schematic diagram of a micro-light emitting element according to another embodiment of the present invention;

[0015] Figure 3B yes Figure 3A A schematic top view of a micro light-emitting element;

[0016] Figure 4A is a cross-sectional schematic diagram of a micro-light emitting element according to another embodiment of the present invention;

[0017] Figure 4B yes Figure 4A A schematic top view of a micro light-emitting element;

[0018] Figure 5 is a cross-sectional schematic diagram of a micro-light emitting element according to another embodiment of the present invention;

[0019] Figure 6 is a cross-sectional schematic diagram of a micro-light emitting element structure according to an embodiment of the present invention;

[0020] Figure 7 is a cross-sectional schematic diagram of a micro-light emitting element structure according to another embodiment of the present invention;

[0021] Figure 8 is a cross-sectional schematic diagram of a micro-light emitting element structure according to another embodiment of the present invention;

[0022] Fig. 9 FIG. 4 is a cross-sectional schematic diagram of a micro-light emitting element structure according to another embodiment of the present invention.

[0023] Description of Reference Numerals

[0024] 10a, 10b, 10c, 10d: micro light emitting element structures;

[0025] 20:Substrate;

[0026] 30: solid crystal adhesive layer;

[0027] 100a, 100a', 100b, 100b', 100c, 100d, 100e, 100f: micro light emitting elements; 110: epitaxial structure;

[0028] 112: first type semiconductor layer;

[0029] 114: active layer;

[0030] 116: second type semiconductor layer;

[0031] 117: outer surface;

[0032] 120: a first electrode;

[0033] 130: second electrode;

[0034] 140: first contact layer;

[0035] 150a, 150a', 150b, 150b', 150c, 150d, 150e, 150f: diffusion structure;

[0036] 152a: lower surface;

[0037] 153c: inner surface;

[0038] 154a: upper surface;

[0039] 155d: outer surface;

[0040] 157e, 157f: first diffusion structure;

[0041] 159e, 159f: second diffusion structure;

[0042] 160: second contact layer;

[0043] 170: insulating layer;

[0044] C: center line;

[0045] D: platform surface;

[0046] G: gap;

[0047] H1: first thickness;

[0048] H2: second thickness;

[0049] H3: third thickness;

[0050] M:Platform. DETAILED DESCRIPTION

[0051] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0052] The embodiments of the present invention can be understood in conjunction with the accompanying drawings, which are also considered part of the disclosure. It should be understood that the drawings of the present invention are not drawn to scale, and in fact, the size of the elements may be arbitrarily enlarged or reduced to clearly show the features of the present invention.

[0053] Figure 1A is a cross-sectional schematic diagram of a micro light-emitting element according to an embodiment of the present invention. Figure 1B yes Figure 1A For the convenience of explanation, Figure 1B Some components are omitted. Please also refer to Figure 1A as well as Figure 1B In this embodiment, the micro-light emitting device 100a includes an epitaxial structure 110, a first electrode 120, a second electrode 130, a first contact layer 140 and a diffusion structure 150a. The epitaxial structure 110 includes a first-type semiconductor layer 112, an active layer 114 and a second-type semiconductor layer 116 stacked in sequence. The second-type semiconductor layer 116 has an outer surface 117 relatively far away from the first-type semiconductor layer 112. The first electrode 120 is disposed on the epitaxial structure 110 and electrically connected to the first-type semiconductor layer 112. The second electrode 130 is disposed on the epitaxial structure 110 and electrically connected to the second-type semiconductor layer 116. The first contact layer 140 is disposed between the first electrode 120 and the first-type semiconductor layer 112. The diffusion structure 150a is disposed on a side of the second-type semiconductor layer 116 away from the first-type semiconductor layer 112. The conductivity of the diffusion structure 150a is less than the conductivity of the second-type semiconductor layer 116. The outer surface 117 of the second-type semiconductor layer 116 exposes the diffusion structure 150 a away from the lower surface 152 a of the first-type semiconductor layer 112 .

[0054] Specifically, in the present embodiment, the micro light emitting element 100a is, for example, a micro light emitting diode (Micro LED) or a microchip. The "micro" element used herein means a size of 1 micron to 100 microns. In some embodiments, the micro element may have a maximum width of 20 microns, 10 microns, or 5 microns. In some embodiments, the micro element may have a maximum height of less than 20 microns, 10 microns, or 5 microns. However, it should be understood that the embodiments of the present invention are not necessarily limited to this, and the implementation of certain embodiments may be applied to larger and perhaps smaller scales.

[0055] Please refer to Figure 1A In this embodiment, the first-type semiconductor layer 112, the active layer 114, and the first portion 116a of the second-type semiconductor layer 116 form a platform M, and the second portion 116a of the second-type semiconductor layer 116 is formed to be recessed relative to the platform M to form a platform surface D. Furthermore, the first electrode 120 and the second electrode 130 of this embodiment are located on the same side of the epitaxial structure 110b, which means that the micro-light-emitting device 100a can be a flip-chip type or a lateral type light-emitting diode. Here, one of the first-type semiconductor layer 112 and the second-type semiconductor layer 116 is a P-type semiconductor layer, and the other of the first-type semiconductor layer 112 and the second-type semiconductor layer 116 is an N-type semiconductor layer, and the active layer 114 is a multiple quantum well (MQW) structure layer. In an embodiment not shown, the second electrode 130 passes through the through hole of the first-type semiconductor layer 112 and is electrically connected to the second-type semiconductor layer 114.

[0056] Furthermore, the micro-light emitting device 100a of the present embodiment further includes an insulating layer 170, which covers from the top surface of the platform M along the side surface to the platform surface D. The first contact layer 140 is disposed between the first electrode 120 and the first-type semiconductor layer 112, wherein the first contact layer 140 directly contacts the first-type semiconductor layer 112 to form an ohmic contact, and the first electrode 120 is disposed on the insulating layer 170 and is electrically connected to the first-type semiconductor layer 112 through the first contact layer 140. On the other hand, the micro-light emitting device 100a of the present embodiment further includes a second contact layer 160, which is disposed between the second electrode 130 and the second-type semiconductor layer 114 and is located on the platform surface D. In an embodiment not shown, the second contact layer of the micro-light emitting device may be disposed between the second electrode and the second-type semiconductor layer and is located in the through hole of the first-type semiconductor layer. The second contact layer 160 directly contacts the second-type semiconductor layer 116 to form an ohmic contact, and the second electrode 130 is disposed on the insulating layer 170 and is electrically connected to the second-type semiconductor layer 116 through the second contact layer 160. Here, the materials of the first contact layer 140 and the second contact layer 160 are, for example, gallium arsenide, double-layer metal titanium / aluminum film, indium tin oxide, antimony tin oxide, indium zinc oxide, zinc tin oxide, high-doped P-type semiconductor or high-doped N-type semiconductor, but are not limited thereto.

[0057] In addition, please also refer to Figure 1A as well as Figure 1B , the diffusion structure 150a of this embodiment is disposed in the second-type semiconductor layer 116 and is located below the first contact layer 140. The orthographic projection of the first contact layer 140 on the active layer 114 overlaps the orthographic projection of the diffusion structure 150a on the active layer 114. Further, the orthographic projection area of ​​the diffusion structure 150a on the active layer 114 is larger than the orthographic projection area of ​​the first contact layer 140 on the active layer 114. Here, the orthographic projection of the diffusion structure 150a on the active layer 114 completely overlaps the orthographic projection of the first contact layer 140 on the active layer 114. Figure 1B As shown, the shape of the orthographic projection of the diffusion structure 150 a is, for example, a circle, but not limited thereto.

[0058] Since the present embodiment is a horizontal micro-light-emitting device 100a, in order to more effectively diffuse the lateral current in the second-type semiconductor layer 116 under the configuration of the horizontal electrodes, the configuration range of the diffusion structure 150a in the vertical direction (i.e., the epitaxial direction) needs to extend the lower surface 152a to the outer surface 117, that is, the outer surface 117 of the second-type semiconductor layer 116 exposes the diffusion structure 150a away from the lower surface 152a of the first-type semiconductor layer 112, so as to avoid the current directly passing through the area between the lower surface 152a and the outer surface 117 without being diffused by the diffusion structure 150a. In short, by exposing the lower surface 152a of the diffusion structure 150a from the outer surface 117 of the second-type semiconductor layer 116, the current diffusion effect can be effectively improved.

[0059] Furthermore, please refer to Figure 1A , the first thickness H1 of the diffusion structure 150a of this embodiment is greater than half of the second thickness H2 of the second semiconductor layer 116. The second contact layer 160 is disposed in the second semiconductor layer 116 at a position of the third thickness H3 away from the lower surface 152a. The first thickness H2 of the diffusion structure 150a is greater than the third thickness H3 of the second portion 116a, so that the diffusion structure 150a can occupy the path of the horizontal flow of carriers from the second contact layer 160 to the first contact layer 140, so as to achieve the effect of diffusion current. There is a gap G between the upper surface 154a of the diffusion structure 150a relative to the lower surface 152a and the active layer 114, which means that the diffusion structure 150a does not directly contact the active layer 114. If the diffusion structure 150a directly contacts the active layer 114, the carriers will not be able to pass through the area of ​​the active layer 114 contacted by the diffusion structure 150a, and the recombination area will become smaller instead. In addition, since the upper surface 154a of the diffusion structure 150a of this embodiment is higher than the second contact layer 160 and there is a gap G between the active layer 114 and the upper surface 154a of the diffusion structure 150a, the effect of diffusing the lateral current can be achieved in the path between the first contact layer 140 and the second contact layer 160.

[0060] Preferably, the material of the diffusion structure 150a of the present embodiment is, for example, a material with low conductivity, such as an inorganic material, an organic material, or a combination of the above materials. The inorganic material may be an oxide or a nitride, such as silicon dioxide or aluminum nitride. The organic material may be a polymer material, such as a resin. Since the diffusion structure 150a in the second-type semiconductor layer 116 is made of a material with low conductivity, the instability of the stress on the epitaxial structure 110 can be reduced. In one embodiment, when the material of the diffusion structure 150a is air, it is a cavity, and the air inside forms an insulating effect, which can avoid changes in conductivity due to ion diffusion.

[0061] It is worth mentioning that the carriers shown in the drawings of this embodiment, ie, positive holes and negative electrons, are only for illustration, and the electrical properties and current directions of the first electrode 120 and the second electrode 130 may be swapped or oppositely configured.

[0062] It must be noted that the following embodiments use the same component numbers and some contents of the previous embodiments, wherein the same number is used to represent the same or similar components, and the description of the same technical contents is omitted. The description of the omitted parts can refer to the previous embodiments, and the following embodiments will not be repeated.

[0063] Figure 1C FIG. 1 is a schematic top view of a micro-light emitting element according to another embodiment of the present invention. Figure 1C Some components are omitted. Please also refer to Figure 1B and Figure 1C The micro-light emitting element 100a' of this embodiment is similar to the above-mentioned micro-light emitting element 100a, and the difference between the two is that in this embodiment, the shape of the orthographic projection of the diffusion structure 150a' of the micro-light emitting element 100a' is, for example, a rectangle, which is specifically a square.

[0064] Figure 2A is a cross-sectional schematic diagram of a micro light-emitting element according to another embodiment of the present invention. Figure 2B yes Figure 2A For the convenience of explanation, Figure 2B Some components are omitted. Please also refer to Figure 1A , Figure 1B , Figure 2A and Figure 2B The micro-light emitting device 100b of this embodiment is similar to the micro-light emitting device 100a described above, and the difference between the two is that in this embodiment, the diffusion structure 150b of the micro-light emitting device 100b is offset inwardly toward the second electrode 130, that is, the horizontal distance between the diffusion structure 150b and the second electrode 130 is smaller than the horizontal distance between the first contact layer 140 and the second electrode 130. In addition to the earlier diffusion of carriers, a better effect of lateral current diffusion can be achieved, and a relatively large active layer 114 area is reserved in the outer region, so that more carriers can be recombined in the outer region of the active layer 114 with a lower carrier density, further improving the internal quantum efficiency.

[0065] Figure 2C FIG. 1 is a schematic top view of a micro-light emitting element according to another embodiment of the present invention. Figure 2C Some components are omitted. Please also refer to Figure 2B and Figure 2CThe micro-light emitting element 100b' of this embodiment is similar to the above-mentioned micro-light emitting element 100b. The difference between the two is that: in this embodiment, the diffusion structure 150b' of the micro-light emitting element 100b' is away from the second electrode 130 (please refer to Figure 2A ) direction is shifted outward.

[0066] Figure 3A is a cross-sectional schematic diagram of a micro light-emitting element according to another embodiment of the present invention. Figure 3B yes Figure 3A For the convenience of explanation, Figure 3B Some components are omitted. Please also refer to Figure 1A , Figure 1B , Figure 3A and Figure 3B The micro-light emitting device 100c of the present embodiment is similar to the micro-light emitting device 100a described above, and the difference between the two is that: in the present embodiment, the center of the diffusion structure 150c of the micro-light emitting device 100c is offset from the first contact layer 140, that is, the diffusion structure 150c is offset outward in a direction away from the second electrode 130, so that the orthographic projection of the diffusion structure 150c on the active layer 114 partially overlaps the orthographic projection of the first contact layer 140 on the active layer 114. At this time, the inner surface 153c of the diffusion structure 150c is, for example, aligned with the center line C of the first contact layer 140, and the horizontal distance between the diffusion structure 150c and the second electrode 130 is greater than the horizontal distance between the first contact layer 140 and the second electrode 130.

[0067] Figure 4A is a cross-sectional schematic diagram of a micro light-emitting element according to another embodiment of the present invention. Figure 4B yes Figure 4A For the convenience of explanation, Figure 4B Some components are omitted. Please also refer to Figure 1A , Figure 1B , Figure 4A and Figure 4B The micro-light emitting device 100d of the present embodiment is similar to the micro-light emitting device 100a described above, and the difference between the two is that in the present embodiment, the center of the diffusion structure 150d of the micro-light emitting device 100d is offset from the first contact layer 140, that is, the diffusion structure 150d is offset inwardly toward the second electrode 130, so that the orthographic projection of the diffusion structure 150d on the active layer 114 partially overlaps the orthographic projection of the first contact layer 140 on the active layer 114. At this time, the outer surface 155d of the diffusion structure 150d is, for example, aligned with the center line C of the first contact layer 140, and the horizontal distance between the diffusion structure 150d and the second electrode 130 is smaller than the horizontal distance between the first contact layer 140 and the second electrode 130.

[0068] Figure 5 is a cross-sectional schematic diagram of a micro-light emitting element according to another embodiment of the present invention. Figure 1A and Figure 5 The micro-light emitting device 100e of the present embodiment is similar to the micro-light emitting device 100a described above, and the difference between the two is that: in the present embodiment, the diffusion structure 150e of the micro-light emitting device 100e includes a first diffusion structure 157e and a second diffusion structure 159e, wherein the first diffusion structure 157e is located between the second diffusion structure 159e and the active layer 114. Here, the material of the first diffusion structure 157e is different from the material of the second diffusion structure 159e. In some embodiments, the conductivity of the material of the first diffusion structure 157e is less than the conductivity of the material of the second diffusion structure 159e, so as to increase the current diffusion effect in the area closer to the active layer 114. In one embodiment, the material of the first diffusion structure 157e is, for example, air, and the material of the second diffusion structure 159e is, for example, an inorganic material, an organic material, or a combination of the above materials. In another embodiment, the material of the first diffusion structure 157e and the material of the second diffusion structure 159e are respectively air, an inorganic material, an organic material, or a combination of the above two materials.

[0069] Figure 6 is a cross-sectional schematic diagram of a micro-light emitting element structure according to an embodiment of the present invention. Figure 6 In this embodiment, the micro-light emitting element structure 10a includes a substrate 20 and a Figure 1A The micro-light emitting device 100a is configured on the substrate 20. Here, the micro-light emitting device structure 10a further includes a bonding layer 30, which is configured on the substrate 20, wherein the lower surface 152a of the diffusion structure 150a of the micro-light emitting device 100a and the outer surface 117 of the second-type semiconductor layer 116 directly contact the bonding layer 30, and the micro-light emitting device 100a is fixed to the substrate 20 through the bonding layer 30.

[0070] Figure 7 is a cross-sectional schematic diagram of a micro-light emitting element structure according to another embodiment of the present invention. Figure 6 and Figure 7The micro-light emitting device structure 10b of this embodiment is similar to the micro-light emitting device structure 10a described above, and the difference between the two is that: in this embodiment, the diffusion structure 150f of the micro-light emitting device 100f includes a first diffusion structure 157f and a second diffusion structure 159f, wherein the second diffusion structure 159f is located between the first diffusion structure 157f and the bonding adhesive layer 30. Here, the material of the first diffusion structure 157f is different from the material of the second diffusion structure 159f. In one embodiment, the material of the first diffusion structure 157f is air, and the material of the second diffusion structure 159f is the same as the material of the bonding adhesive layer 30. The second diffusion structure 159f can be formed by filling the bonding adhesive when the micro-light emitting device 100f is bonded to the substrate 20. In some embodiments, the Young's modulus of the material of the first diffusion structure 157f is greater than the Young's modulus of the material of the second diffusion structure 159f, and the mechanical strength inside the micro-light emitting device 100f is higher, and a buffer effect can be provided at the connection between the micro-light emitting device 100f and the substrate 20. In one embodiment, the material of the first diffusion structure 157f is an inorganic material, an organic material or a combination of the two materials, and the material of the second diffusion structure 159f is the same as the material of the bonding adhesive layer 30. In another embodiment, the material of the diffusion structure 150f can also be completely the same as the material of the bonding adhesive layer 30, that is, there is no air.

[0071] Figure 8 is a cross-sectional schematic diagram of a micro-light emitting element structure according to another embodiment of the present invention. Figure 6 and Figure 8 The micro-light emitting device structure 10c of this embodiment is similar to the above-mentioned micro-light emitting device structure 10a, and the difference between the two is that in this embodiment, a plurality of micro-light emitting devices 100a are separately disposed on the substrate 20.

[0072] Fig. 9 is a cross-sectional schematic diagram of a micro-light emitting element structure according to another embodiment of the present invention. Figure 7 and Fig. 9 The micro-light emitting element structure 10d of this embodiment is similar to the above-mentioned micro-light emitting element structure 10b, and the difference between the two is that in this embodiment, a plurality of micro-light emitting elements 100f are separately disposed on the substrate 20.

[0073] In summary, in the design of the micro-light-emitting device of the present invention, the diffusion structure is disposed on the side of the second-type semiconductor layer away from the first-type semiconductor layer, wherein the conductivity of the diffusion structure is less than the conductivity of the second-type semiconductor layer, and the outer surface of the second-type semiconductor layer exposes the lower surface of the diffusion structure away from the first-type semiconductor layer. Through the design of the diffusion structure, carriers can be effectively blocked from flowing directly to the original recombination area, forcing the current to be diffused to a larger range, thereby increasing the uniformity of the current density to improve the internal quantum efficiency.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A micro light-emitting element, characterized in that: include: An epitaxial structure comprises a first-type semiconductor layer, an active layer and a second-type semiconductor layer stacked in sequence, wherein the second-type semiconductor layer has an outer surface relatively far away from the first-type semiconductor layer; A first electrode, disposed on the epitaxial structure and electrically connected to the first-type semiconductor layer; A second electrode is disposed on the epitaxial structure and electrically connected to the second-type semiconductor layer; A first contact layer, disposed between the first electrode and the first-type semiconductor layer; as well as A diffusion structure is arranged on a side of the second-type semiconductor layer away from the first-type semiconductor layer, wherein the conductivity of the diffusion structure is less than the conductivity of the second-type semiconductor layer, and the outer surface of the second-type semiconductor layer exposes the lower surface of the diffusion structure away from the first-type semiconductor layer.

2. The micro-light emitting element according to claim 1, characterized in that: A gap is formed between an upper surface of the diffusion structure relative to the lower surface and the active layer.

3. The micro-light emitting element according to claim 1, characterized in that: The first thickness of the diffusion structure is greater than half of the second thickness of the second-type semiconductor layer.

4. The micro-light emitting element according to claim 1, characterized in that: The orthographic projection of the first contact layer on the active layer overlaps with the orthographic projection of the diffusion structure on the active layer.

5. The micro-light emitting element according to claim 4, characterized in that: An orthographic projection area of ​​the diffusion structure on the active layer is larger than an orthographic projection area of ​​the first contact layer on the active layer.

6. The micro-light emitting element according to claim 1, characterized in that: Also includes: The second contact layer is disposed between the second electrode and the second-type semiconductor layer, and has a third thickness between the second contact layer and the outer surface.

7. The micro-light emitting element according to claim 6, characterized in that: The first-type semiconductor layer, the active layer and the first part of the second-type semiconductor layer form a platform, the second part of the second-type semiconductor layer is recessed relative to the platform to form a platform surface, and the second contact layer is located on the platform surface.

8. The micro-light emitting element according to claim 7, characterized in that: The first thickness of the diffusion structure is greater than the third thickness.

9. The micro-light emitting element according to claim 1, characterized in that: The material of the diffusion structure includes air, organic material, inorganic material or a combination of the above materials.

10. A micro light-emitting element structure, characterized in that: include: substrate; as well as A plurality of micro-light emitting elements are separately disposed on the substrate, wherein each of the plurality of micro-light emitting elements comprises: An epitaxial structure comprises a first-type semiconductor layer, an active layer and a second-type semiconductor layer stacked in sequence, wherein the second-type semiconductor layer has an outer surface relatively far away from the first-type semiconductor layer; A first electrode, disposed on the epitaxial structure and electrically connected to the first-type semiconductor layer; A second electrode is disposed on the epitaxial structure and electrically connected to the second-type semiconductor layer; A first contact layer is disposed between the first electrode and the first-type semiconductor layer; and The diffusion structure is arranged on a side of the second-type semiconductor layer away from the first-type semiconductor layer, wherein the conductivity of the diffusion structure is less than the conductivity of the second-type semiconductor layer, and the outer surface of the second-type semiconductor layer exposes the lower surface of the diffusion structure away from the first-type semiconductor layer.

11. The micro-light emitting element structure according to claim 10, characterized in that: Also includes: A bonding glue layer is disposed on the substrate, the lower surface of the diffusion structure of each of the plurality of micro-light-emitting elements and the outer surface of the second-type semiconductor layer directly contact the bonding glue layer, and each of the plurality of micro-light-emitting elements is fixed to the substrate through the bonding glue layer.

12. The micro-light emitting element structure according to claim 11, characterized in that: The diffusion structure includes a first diffusion structure and a second diffusion structure. The second diffusion structure is located between the first diffusion structure and the bonding adhesive layer. The first diffusion structure and the second diffusion structure are made of different materials.

13. The micro-light emitting element structure according to claim 12, characterized in that: The material of the second diffusion structure is the same as that of the die-bonding adhesive layer.

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