Micro light emitting diode with high light extraction efficiency

Abstract

To provide a micro light emitting diode (LED) having a high light extraction efficiency.SOLUTION: A micro light emitting diode (LED) having a high light extraction efficiency includes a bottom conductive layer, a light emitting layer on the bottom conductive layer, and a top conductive structure on the light emitting layer. The micro LED additionally includes a conductive side arm electrically connecting the sidewall of the light emitting layer with the bottom conductive layer, and a reflective bottom dielectric layer arranged under the light emitting layer and above the bottom conductive layer. In some embodiments, the micro LED further includes an ohmic contact between the top conductive structure and the light emitting layer that has a small area and is transparent, thereby increasing the light emergent area and improving the light extraction efficiency.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 965,889, entitled "MICRO LIGHT EMITTING DIODE WITH HIGH LIGHT EXTRACTION EFFICIENCY," filed on January 25, 2020, which is incorporated by reference herein.

[0002] Technical Field The present disclosure relates generally to display devices, and more particularly to systems and manufacturing methods for micro light emitting diodes (LEDs) with high light extraction efficiency. [Background technology]

[0003] background

[0003] Display technology is becoming more and more popular in today's commercial electronic devices. These display panels are widely used in stationary large screens such as liquid crystal display televisions (LCD TVs) and organic light emitting diode televisions (OLED TVs) as well as portable electronic devices such as laptop personal computers, smartphones, tablets, and wearable electronic devices. With the recent development of mini-LED and micro-LED technologies, consumer devices and applications such as augmented reality (AR), projection, head-up displays (HUDs), mobile device displays, wearable device displays, and automotive displays require LED panels with improved efficiency and resolution. For example, an AR display integrated into goggles and placed close to the wearer's eyes may have the dimensions of a fingernail while still requiring HD resolution (1280×720 pixels) or higher.

[0004]

[0004] A light emitting diode (LED) is a junction luminescent device, and the main structure of an LED is a PN junction. Under forward bias, the PN junction emits visible light or infrared light. The luminous efficiency of an LED depends on the epitaxy material, ohmic contact electrodes, chip structure, geometric shape, etc.

[0005]

[0005] In the current technology for LEDs, the formation of P-type LEDs is a big challenge. For example, it is difficult to dope P-GaN LEDs due to the lack of high work function metals that match P-GaN. In addition, low ohmic contact resistance is required by controlling annealing temperature, time, atmosphere, etc. The electrodes need to be transparent to ensure the transmission of light from the LED. Generally, Au / Ni alloys are required to form good ohmic contacts. Since gold is not transparent to the emitted wavelengths, the metal electrodes will block the incident light. Therefore, the electrodes cannot be made too thick. However, if the electrodes are too thin, the thin layer of the electrode can cause uneven diffusion of the current, resulting in overheating in localized areas, and reduced transparency of the electrode.

[0006]

[0006] Many developments in LED displays are aimed at improving the efficiency of LEDs. For example, flip-chip LED structures are realized by turning an LED structure upside down and bonding the flipped LED structure to a substrate with electrodes. Compared with other structures, flip-chip LED structures have many advantages in terms of efficiency and technological maturity, because they can reduce the photons absorbed by the P-type ohmic contact electrode and avoid the emitted light being blocked by the electrode. Although flip-chip LEDs have been widely researched, the limitations of the total reflection effect have not yet been overcome, and the improvement of light extraction efficiency is limited.

[0007]

[0007] Although Bragg mirrors are usually used to improve reflectivity, they only exhibit high reflectivity for perpendicularly incident light. They have low reflectivity for obliquely incident light. In such a situation, total reflection cannot be achieved.

[0008]

[0008] Furthermore, adding a rear reflector structure to a flip-chip LED structure reduces the contact area between the metal electrode and the semiconductor material, and the ohmic contact resistance increases significantly. The rear contact formed in the rear reflector structure reduces the reflective area of ​​the rear reflector structure, which in turn reduces the reflectivity of the reflective structure and the light extraction efficiency of the LED.

[0009]

[0009] In addition, in flip-chip LED structures, low work function metals are required for the electrodes to realize N-GaN ohmic contacts, and since the area remaining after the etching process is limited, it is very difficult to fabricate N-type ohmic contacts. Summary of the Invention [Problem to be solved by the invention]

[0010] overview

[0010] There is a need for improved LED designs that help improve upon and address the shortcomings of conventional LED systems and structures such as those described above. In particular, there is a need for display panels having highly efficient micro-LED structures with good ohmic contacts, large extraction areas, high reflectivities, and high extraction efficiencies. [Means for solving the problem]

[0011] Various embodiments include a display panel that includes an array of pixel light sources (eg, LEDs, OLEDs) electrically coupled to corresponding pixel driver circuits (eg, FETs).

[0012]

[0012] In some embodiments, a micro light-emitting diode with high light extraction efficiency includes a bottom conductive layer, a light-emitting layer on the bottom conductive layer, a top conductive structure on the light-emitting layer, a bottom dielectric layer disposed between the bottom conductive layer and the light-emitting layer, and a conductive side arm connecting a sidewall of the bottom layer of the light-emitting layer and the bottom conductive layer.

[0013]

[0013] In some embodiments, the micro light-emitting diode further includes an ohmic contact layer disposed between the upper conductive structure and the light-emitting layer.

[0014] In some embodiments, the lateral width of the ohmic contact layer is much narrower than the lateral width of the light emitting layer.

[0015] In some embodiments, the top conductive structure directly covers the ohmic contact layer, such that a substantial portion of the light emitting layer is not shielded by the ohmic contact layer.

[0016] In some embodiments, the ohmic contact layer is a metal film.

[0017] In some embodiments, the thickness of the ohmic contact layer is less than 20 nm and the lateral width of the ohmic contact layer is less than 0.5 μm.

[0018] In some embodiments, the material of the ohmic contact layer comprises at least one or more selected from the group consisting of metals from Groups I, II, III, IV, VI, and VIII of the periodic table.

[0019] In some embodiments, the upper conductive structure is transparent and the ohmic contact layer is transparent.

[0020] In some embodiments, the bottom dielectric layer is a composite reflective layer.

[0021]

[0021] In some embodiments, the composite reflective layer includes multiple layers including at least an insulating reflective dielectric layer and a composite metal reflective layer, where the composite metal reflective layer is disposed at the bottom of the insulating reflective dielectric layer and in contact with the bottom conductive layer.

[0022] In some embodiments, the composite metal reflective layer has multiple layers.

[0023] In some embodiments, the insulating reflective dielectric layer further comprises a top insulating dielectric layer and a bottom Bragg mirror.

[0024] In some embodiments, the upper insulating dielectric layer has three or more layers.

[0025] In some embodiments, the material of the upper insulating dielectric layer is a metal oxide.

[0026]

[0026] In some embodiments, the lateral width of the bottom conductive layer is greater than the lateral width of the bottom dielectric layer, such that the bottom conductive layer has a protruding top extending outside the bottom dielectric layer, one end of the conductive side arm is connected to the bottom layer of the light emitting layer, and at least a portion of another end of the conductive side arm is connected to and supported on the protruding top of the bottom conductive layer.

[0027] In some embodiments, the lateral width of the bottom dielectric layer is greater than or equal to the width of the bottom of the light emitting layer.

[0028] In some embodiments, the light emitting layer further includes, in order from top to bottom, a first type semiconductor layer, an active layer, and a second type semiconductor layer. In some embodiments, the second type semiconductor layer has a protruding top extending outside the active layer and the first type semiconductor layer, one end of the conductive side arm covers and contacts the protruding top of the second type semiconductor layer, and the other end of the conductive side arm contacts the bottom conductive layer.

[0029] In some embodiments, the lateral width of the bottom conductive layer is greater than the lateral width of the second type semiconductor layer and the lateral width of the bottom dielectric layer, such that the bottom conductive layer has a protruding top that extends outside the second type semiconductor layer and the bottom dielectric layer. In some embodiments, at least a portion of the conductive side arms are supported on the protruding top of the bottom conductive layer.

[0030] In some embodiments, the lateral width of the bottom conductive layer is less than 2 μm.

[0031] In some embodiments, the width of the protruding top of the bottom conductive layer is less than or equal to the width of the protruding top of the second type of semiconductor layer.

[0032]

[0032] In some embodiments, the second type semiconductor layer further comprises a second type top semiconductor layer and a second type bottom semiconductor layer, the second type bottom semiconductor layer extending outward relative to the second type top semiconductor layer, thereby forming a protruding top.

[0033] In some embodiments, the material of the top semiconductor layer of the second type is different from the material of the bottom semiconductor layer of the second type.

[0034] In some embodiments, the top semiconductor layer of the second type is AlGaInP, the bottom semiconductor layer of the second type is GaP, and the semiconductor layer of the first type is AlInP.

[0035]

[0035] In some embodiments, the ends of the conductive side arms are in electrical contact with the protruding upper portion of the second type bottom semiconductor layer, are not in electrical contact with the second type top semiconductor layer, and are not in electrical contact with the light emitting layer and the first type semiconductor layer.

[0036] In some embodiments, the lateral width of the first type semiconductor layer is greater than or equal to the lateral width of the active layer.

[0037] In some embodiments, the lateral width of the first type semiconductor layer is much narrower than the lateral width of the active layer.

[0038] In some embodiments, the conductive side arm has an inverted L-shape.

[0039] In some embodiments, the conductive side arms are attached and connected to the sidewalls of the bottom dielectric layer.

[0040]

[0040] In some embodiments, the lateral width of the bottom conductive layer is greater than the lateral width of the bottom dielectric layer, and the sidewalls of the bottom conductive layer protrude outside and beyond the sidewalls of the conductive side arms.

[0041]

[0041] In some embodiments, the micro light-emitting diode further includes a transparent insulating layer covering at least the protruding upper portion of the second type semiconductor layer, the upper portion and sidewalls of the conductive side arms, the sidewalls of the light-emitting layer, and the sidewalls of the first type semiconductor layer, and the upper conductive structure is disposed on top of the transparent insulating layer.

[0042] In some embodiments, the material of the conductive side arms is a conductive metal.

[0043] In some embodiments, the first type semiconductor layer is an N-type semiconductor layer and the second type semiconductor layer is a P-type semiconductor layer.

[0044] In some embodiments, the first type semiconductor layer is a P-type semiconductor layer and the second type semiconductor layer is an N-type semiconductor layer.

[0045] In some embodiments, the material of the bottom conductive layer includes one or more types of conductive metals.

[0046]

[0046] In some embodiments, the micro light-emitting diode further includes an electrical circuit base at the bottom of the bottom conductive layer, and the bottom conductive layer is used as an adhesive layer bonded to the surface of the electrical circuit base.

[0047] In some embodiments, the electrical circuit base includes at least a drive circuit that controls the emission of the light-emitting layer.

[0048]

[0048] In some embodiments, the micro light emitting diode has a light extraction efficiency of at least 20%.

[0049]

[0049] In some embodiments, the micro light emitting diode has a light extraction efficiency of at least 40%.

[0050]

[0050] In some embodiments, the micro light emitting diode has a light extraction efficiency of at least 60%.

[0051]

[0051] It should be noted that the various embodiments described above can be combined with any other embodiments described herein. The features and advantages described herein are not all-inclusive, and in particular many additional features and advantages will be apparent to those skilled in the art in view of the drawings, specification, and claims. Furthermore, it should be noted that the terms used in this specification are primarily selected for ease of reading and instructional purposes, and may not be selected to delineate or limit the scope of the present invention.

[0052] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order that the present disclosure may be understood in more detail, a more particular description may be made by referring to the features of various embodiments, some of which are illustrated in the accompanying drawings. However, the accompanying drawings merely illustrate the relevant features of the present disclosure and should therefore be considered as illustrative rather than limiting, and other useful features may be recognized. [Brief description of the drawings]

[0053] [Figure 1]

[0053] FIG. 1 is a cross-sectional view of a micro LED structure according to a first embodiment. [Diagram 2]

[0054] FIG. 2 is a cross-sectional view of a micro LED structure according to a second embodiment. [Diagram 3]

[0055] FIG. 11 is a cross-sectional view of a micro LED structure according to a third embodiment. [Figure 4]

[0056] 1 illustrates a cross-sectional view of a bottom dielectric layer structure of a micro LED structure according to some embodiments. [Diagram 5]

[0057] 1 illustrates a cross-sectional view of a bottom dielectric layer structure of a micro LED structure according to some embodiments. [Figure 6]

[0058] FIG. 11 is a cross-sectional view of a micro LED structure according to a fourth embodiment. [Figure 7]

[0059] FIG. 13 is a cross-sectional view of a micro LED structure according to a fifth embodiment. [Figure 8]

[0060] FIG. 13 is a cross-sectional view of a micro LED structure according to a sixth embodiment. [Figure 9]

[0061] FIG. 13 is a cross-sectional view of a micro LED structure according to a seventh embodiment. [Figure 10]

[0062] FIG. 13 is a cross-sectional view of a micro LED structure according to an eighth embodiment. [Figure 11]

[0063] FIG. 13 is a cross-sectional view of a micro LED structure according to a ninth embodiment. [Figure 12]

[0064] FIG. 12 is a top view of a micro-LED display panel 1200, according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054]

[0065] According to common practice, the various features illustrated in the figures are not drawn to scale. Thus, dimensions of the various features may be arbitrarily expanded or reduced for clarity. In addition, some of the figures may not depict all of the components of a given system, method, or device. Finally, like reference numerals may be used to denote like features throughout the specification and figures.

[0055] Detailed Description

[0066] Numerous details are described herein to provide a thorough understanding of the example embodiments shown in the accompanying drawings. However, some embodiments may be practiced without many of the specific details, and the claims are limited only by the features and aspects specifically described in the claims. Moreover, well-known processes, components, and materials have not been described in detail so as not to unnecessarily obscure relevant aspects of the embodiments described herein. Reference will now be made in detail to preferred embodiments of the invention to provide a further understanding of the invention. The specific embodiments discussed and the accompanying drawings are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention or the appended claims.

[0056]

[0067] Embodiments consistent with the present disclosure include a display panel including a substrate having an array of pixel driver circuits, an array of LEDs formed on the substrate having the structure described below, and a method of making the display panel. A display panel with high light extraction efficiency can overcome the shortcomings of conventional display systems.

[0057]

[0068] FIG. 1 is a cross-sectional view of a micro LED structure according to a first embodiment. The micro LED structure 100 shown in FIG. 1 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the micro LED includes a bottom conductive layer 102, a light emitting layer 106 on the bottom conductive layer 102, and a top conductive structure 108 on the light emitting layer 106. In some embodiments, the micro LED further includes a bottom dielectric layer 104 disposed between the bottom conductive layer 102 and the light emitting layer 106. In some embodiments, the bottom dielectric layer 104 is part of the light emitting layer 106. In some embodiments, the light emitting layer 106 includes many different layers. In some embodiments, a conductive side arm 110 connects a sidewall of the bottom layer or bottom (not shown separately in FIG. 1) of the light emitting layer 106 to the bottom conductive layer 102. In some embodiments, the conductive side arms 110 are on either side of the micro LED structure. In some embodiments, the top conductive structure 108 forms a top conductive structure which is not limited by the scope of this embodiment. In some embodiments, the shape of the top conductive structure is a line, a square, a rectangle, or some other shape.

[0058]

[0069] FIG. 2 is a cross-sectional view of a micro LED structure according to a second embodiment. The micro LED structure 200 shown in FIG. 2 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the light extraction efficiency is at least 50%. In some embodiments, the micro LED structure 200 of FIG. 2 is based on the micro LED structure 100 of FIG. 1. Similar to the micro LED structure 100 in FIG. 1, the micro LED structure 200 includes a bottom conductive layer 202, a light emitting layer 206, a bottom dielectric layer 204, a top conductive structure 208, and a conductive side arm 210. In addition, in some embodiments, the bottom conductive layer 202 connected to the conductive side arm 210 has a protruding bottom 202-1, such that the bottom of the conductive side arm 210 is at least partially, or alternatively completely, supported by the protruding bottom 202-1 of the bottom conductive layer 202. In one example, the sidewalls of the conductive side arms 210 are aligned with the sidewalls of the protruding bottom 202-1 of the bottom conductive layer 202, as shown in FIG. 2. Furthermore, in some embodiments, an ohmic contact layer 212 is disposed between the top conductive structure 208 and the light emitting layer 206. In some embodiments, the ohmic contact layer 212 is a metal film. The components of the metal film of the ohmic contact layer 212 are at least selected from one or more of Groups I, II, III, IV, VI, and VIII of the periodic table, and combinations thereof, such as Au, Cr, Be, Zn, Pt, Ti, Ge, Ni, In, and combinations thereof. In some embodiments, when light is emitted from the top of the LED 200, a top conductive structure that is transparent to the emitted light, such as an indium tin oxide (ITO) transparent conductive film, is used as the top conductive structure 208. In some embodiments, the ohmic contact layer 212 is transparent to the emitted light. Preferably, when the thickness of the ohmic contact layer 212 is less than 20 nm, the ohmic contact layer 212 can be transparent to the emitted light.

[0059]

[0070] FIG. 3 is a cross-sectional view of a micro LED structure according to a third embodiment. The micro LED structure 300 shown in FIG. 3 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the light extraction efficiency is at least 50%. In some embodiments, the light extraction efficiency is at least 60%. In some embodiments, the micro LED structure 300 of FIG. 3 is based on the micro LED structure 200 of FIG. 2. Similar to the micro LED structure 200 of FIG. 2, the micro LED structure 300 includes a bottom conductive layer 302, a light emitting layer 306, a bottom dielectric layer 304, a top conductive structure 308, a conductive side arm 310, a protruding bottom portion 302-1 of the bottom conductive layer 302 below the conductive side arm 310, and an ohmic contact layer 312. In some embodiments, the width of the ohmic contact layer 312 is much narrower than the width of the light emitting layer 306 so as to form an ohmic contact point. The upper conductive structure 308 covers the ohmic contact layer 312, and the light emitting layer 306 is not completely shielded by the ohmic contact layer 312. In some embodiments, the lateral width of the ohmic contact layer 312 is less than 1 μm, preferably less than 0.5 μm, to improve light extraction efficiency. In some embodiments, the thickness of the ohmic contact layer 312 is less than 20 nm to improve light transmittance of the ohmic contact layer 312. In some embodiments, the material of the ohmic contact layer 312 depends on the type of the light emitting layer 306 and the material of the upper conductive structure 308. In some embodiments, the material of the ohmic contact layer 312 is a metal. In some preferred embodiments, the ohmic contact layer 312 has multiple layers formed of a composite metal material, such as the material used by the ohmic contact layer 212 of FIG. 2.

[0060]

[0071] FIG. 4 shows a cross-sectional view of the structure of the bottom dielectric layer of a micro LED structure according to some embodiments. The bottom dielectric layer 404 can be used as the bottom dielectric layer in FIGS. 1-3. The bottom dielectric layer 404 has a reflectivity. In some embodiments, the bottom dielectric layer 404 has a reflectivity of more than 50%. In some embodiments, the bottom dielectric layer 404 has a reflectivity of more than 70%. In some embodiments, the bottom dielectric layer 404 has a reflectivity of more than 90%. In some preferred embodiments, the bottom dielectric layer 404 is a composite reflective layer, which increases the reflective area and improves the reflective efficiency. As shown in FIG. 4, the composite reflective layer 404 has multiple layers, including at least an insulating reflective dielectric layer 404-1 and a composite metal reflective layer 404-2. In some embodiments, the composite metal reflective layer 404-2 is disposed at the bottom of the insulating reflective dielectric layer 404-1. In some embodiments, the composite metal reflective layer 404-2 is in contact with the bottom conductive layer shown in FIGS. 1-3. In some embodiments, the material of the composite metal reflective layer 404-2 is similar or identical to the material of the bottom conductive layer, such as Cr and / or Au, which is used not only as a reflective layer but also as a buffer layer between the insulating reflective dielectric layer 404-1 and the bottom conductive layer. The composite metal reflective layer 404-2 further increases the adhesion between the insulating reflective dielectric layer 404-1 and the bottom conductive layer, so that the insulating reflective dielectric layer 404-1 and the bottom conductive layer are firmly bonded together.

[0061]

[0072] FIG. 5 shows a cross-sectional view of the structure of the bottom dielectric layer of a micro LED structure according to some embodiments. The bottom dielectric layer 504 can be used as the bottom dielectric layer in FIGS. 1-4. In some embodiments, the bottom dielectric layer 504 includes an insulating reflective dielectric layer 504-1 and a composite metal reflective layer 504-2. In some embodiments, the insulating reflective dielectric layer 504-1, also shown in FIG. 4, includes a top insulating dielectric layer 504-11 and a bottom distributed Bragg reflector (DBR) 504-12. In some embodiments, the material of the top insulating dielectric layer 504-11 is a metal oxide, and in some cases, the material of the top insulating dielectric layer 504-11 further includes Si, In, or / and Sn, etc. In some embodiments, a multi-layer Bragg mirror (DBR) is used as the bottom BBR 504-12, which is known to those skilled in the art and will not be further described herein. In some embodiments, the top insulating dielectric layer 504-11 can increase the transmittance and refractive index of light rays so that the light rays are effectively incident on the bottom DBR 504-12. In some embodiments, the top insulating dielectric layer 504-11 includes multiple layers, such as three or more layers.

[0062]

[0073] FIG. 6 is a cross-sectional view of a micro LED structure according to a fourth embodiment. The micro LED structure 600 shown in FIG. 6 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the light extraction efficiency is at least 50%. In some embodiments, the light extraction efficiency is at least 60%. In some embodiments, the micro LED structure 600 of FIG. 6 is based on the micro LED structure 300 of FIG. 3. Similar to the micro LED structure 300 in FIG. 3, the micro LED structure 600 includes a bottom conductive layer 602, a light emitting layer 606, a bottom dielectric layer 604, a top conductive structure 608, a conductive side arm 610, and an ohmic contact layer 612 that is much narrower than the light emitting layer 606 to form an ohmic contact point. In some embodiments, as shown in FIG. 6, the lateral width of the bottom conductive layer 602 is greater than the lateral width of the composite reflective layer (bottom dielectric layer 604), so that the bottom conductive layer 602 has a protruding top 602-2 that protrudes outward. In some embodiments, one end of the conductive side arm 610 is connected to the bottom layer or bottom (not shown separately in FIG. 6) of the light emitting layer 606, and at least a portion of the other end of the conductive side arm 610 is connected to the protruding top 602-2 of the bottom conductive layer 602. As shown in FIG. 6, a portion of the bottom of the conductive side arm 610 is supported on the protruding top 602-2 of the bottom conductive layer 602. In some embodiments, to ensure high extraction efficiency of the micro LED structure 600, the lateral width of the bottom conductive layer 602 is less than 2 μm, and preferably in the range of 0.3 to 2 μm.

[0063]

[0074] FIG. 7 is a cross-sectional view of a micro LED structure according to a fifth embodiment. The micro LED structure 700 shown in FIG. 7 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the light extraction efficiency is at least 50%. In some embodiments, the light extraction efficiency is at least 60%. In some embodiments, the micro LED structure 700 of FIG. 7 is based on the micro LED structure 600 of FIG. 6. Similar to the micro LED structure 600 in FIG. 6, the micro LED structure 700 includes a bottom conductive layer 702, a light emitting layer 706, a bottom dielectric layer 704, a top conductive structure 708, conductive side arms 710, and an ohmic contact layer 712 that is much narrower than the light emitting layer 706 to form an ohmic contact point. And the lateral width of the bottom conductive layer 702 is greater than the lateral width of the composite reflective layer (bottom dielectric layer 704), so that the bottom conductive layer 702 has an outwardly protruding top 702-2. In some embodiments, the bottom conductive layer 702 has an outwardly protruding top 702-2 relative to the bottom dielectric layer 704, so that the bottom of the conductive side arm 710 is at least partially, or alternatively completely, supported on the protruding top 702-2 of the bottom conductive layer 702. In one example, the sidewall of the conductive side arm 710 is aligned with the sidewall of the bottom conductive layer 702, as shown in FIG.

[0064]

[0075] 6 and 7, in some examples, the lateral width of bottom dielectric layer 704 is equal to or greater than the width of the bottom of light emitting layer 706, and the sidewalls of light emitting layer 706 are vertical or sloped. In other examples, the lateral width of bottom dielectric layer 704 can be less than the width of the bottom of light emitting layer 706, while the conductive side arms 710 are L-shaped.

[0065]

[0076] FIG. 8 is a cross-sectional view of a micro LED structure according to a sixth embodiment. The micro LED structure 800 shown in FIG. 8 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the light extraction efficiency is at least 50%. In some embodiments, the light extraction efficiency is at least 60%. In some embodiments, the micro LED structure 800 of FIG. 8 is based on the micro LED structure 700 of FIG. 7. Similar to the micro LED structure 700 in FIG. 7, the micro LED structure 800 includes a bottom conductive layer 802, a light emitting layer 806, a bottom dielectric layer 804, a top conductive structure 808, conductive side arms 810, and an ohmic contact layer 812 that is much narrower than the light emitting layer 806 to form an ohmic contact point. And the lateral width of the bottom conductive layer 802 is larger than the lateral width of the composite reflective layer (bottom dielectric layer 804), so that the bottom conductive layer 802 has a protruding top 802-2 protruding outward, and the bottom of the conductive side arm 810 is at least partially, or alternatively completely, supported on the protruding top 802-2 of the bottom conductive layer 802. In one example, the sidewall of the conductive side arm 810 is aligned with the sidewall of the bottom conductive layer 802, as shown in FIG. 8. In some embodiments, the lateral width of the bottom of the light emitting layer 806 is smaller than the lateral width of the bottom dielectric layer 804. In some embodiments, the conductive side arm 810 has an inverted L-shape. The conductive side arm 810 includes a horizontal portion 810-1 and a vertical portion 810-2. An end of horizontal portion 810-1 extends to and contacts the bottom layer or bottom (not shown separately in FIG. 8 ) of light emitting layer 806, while an end of vertical portion 810-2 extends to and contacts the bottom conductive layer 802.

[0066]

[0077] FIG. 9 is a cross-sectional view of a micro LED structure according to a seventh embodiment. The micro LED structure 900 shown in FIG. 9 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the light extraction efficiency is at least 50%. In some embodiments, the light extraction efficiency is at least 60%. In some embodiments, the light extraction efficiency is at least 70%. In some embodiments, the micro LED structure 900 of FIG. 9 is based on the micro LED structure 800 of FIG. 8. Similar to the micro LED structure 800 in FIG. 8, the micro LED structure 900 includes a bottom conductive layer 902, a light emitting layer 906, a bottom dielectric layer 904, a top conductive structure 908, conductive side arms 910, and an ohmic contact layer 912 that is much narrower than the light emitting layer 906 to form an ohmic contact point. Furthermore, the lateral width of the bottom conductive layer 902 is greater than the lateral width of the composite reflective layer (bottom dielectric layer 904), such that the bottom conductive layer 902 has a protruding top 902-2 that protrudes outward, and the bottom of the conductive side arm 910 is at least partially, or alternatively completely, supported on the protruding top 902-2 of the bottom conductive layer 902. In one example, the sidewall of the conductive side arm 910 is aligned with the sidewall of the bottom conductive layer 902, as shown in FIG. 9. In some embodiments, the conductive side arm 910 has an inverted L-shape. The conductive side arm 910 includes a horizontal portion 910-1 and a vertical portion 910-2.

[0067]

[0078] As shown in FIG. 9, in some embodiments, the light emitting layer 906 comprises, from top to bottom, a first type semiconductor layer 906-1, an active layer 906-2, and a second type semiconductor layer 906-3. In some embodiments, the second type semiconductor layer 906-3 has a lateral width greater than the lateral width of the first type semiconductor layer 906-1 and the lateral width of the active layer 906-2, thus forming a protruding upper portion 906-3-3 at the edge of the second type semiconductor layer 906-3. In some embodiments, the lateral width of the first type semiconductor layer 906-1 is the same as the lateral width of the active layer 906-2. In some embodiments, the lateral width of the first type semiconductor layer 906-1 is the same as the lateral width of the upper conductive structure 908.

[0068]

[0079] In some embodiments, an end of the horizontal portion 910-1 of the conductive side arm 910 covers and contacts the protruding upper portion 906-3-3 of the second type semiconductor layer 906-3, and the other end of the vertical portion 910-2 of the conductive side arm 910 contacts the bottom conductive layer 902.

[0069]

[0080] In some embodiments, the first type semiconductor layer 906-1 is an N-type semiconductor layer and the second type semiconductor layer 906-3 is a P-type semiconductor layer. Alternatively, in some embodiments, the first type semiconductor layer 906-1 is a P-type semiconductor layer and the second type semiconductor layer 906-3 is an N-type semiconductor layer. In some embodiments, the material of the N-type semiconductor is N-type AlInP or N-type GaAs, or a composite material of various N-type semiconductor layers. In some embodiments, the material of the P-type semiconductor layer is P-type GaP or P-type AlGaInP.

[0070]

[0081] In some embodiments, the lateral width of the bottom conductive layer 902 is greater than the lateral width of the second type semiconductor layer 906-3. In some embodiments, the lateral width of the second type semiconductor layer 906-3 is equal to the lateral width of the bottom dielectric layer 904. The bottom conductive layer 902 has a protruding top 902-2 that extends outward relative to the second type semiconductor layer 906-3 and the bottom dielectric layer 904. In some embodiments, at least a portion of the conductive side arm 910 is at least partially, or alternatively completely, supported on the protruding top 902-2 of the bottom conductive layer 902. In some embodiments, the entire bottom of the conductive side arm 910 is supported on the protruding top 902-2 of the bottom conductive layer 902, as shown in FIG.

[0071]

[0082] In some embodiments, the end of the conductive side arm 910 that connects to the protruding top 906-3-3 of the second type semiconductor layer 906-3 is not directly connected to the active layer 906-2. As shown in FIG. 9, there is a gap between the vertical sidewall of the horizontal portion 910-1 of the conductive side arm 910 and the active layer 906-2. In some preferred embodiments, the lateral width of the protruding top 902-2 of the bottom conductive layer 902 (only the width of the portion that extends outside the bottom dielectric layer 904) is equal to or less than the width of the protruding top 906-3-3 of the second type semiconductor layer 906-3 (only the width of the portion that extends outside the active layer 906-2). Such an arrangement of the widths ensures that the bottom end of the conductive side arm 910 rests on the bottom conductive layer 902 and avoids the top end of the conductive side arm 910 contacting the active layer 906-2, thereby forming a stable and reliable electrical contact structure.

[0072]

[0083] FIG. 10 is a cross-sectional view of a micro LED structure according to an eighth embodiment. The micro LED structure 1000 shown in FIG. 10 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the light extraction efficiency is at least 50%. In some embodiments, the light extraction efficiency is at least 60%. In some embodiments, the light extraction efficiency is at least 70%. In some embodiments, the light extraction efficiency is at least 80%. In some embodiments, the micro LED structure 1000 of FIG. 10 is based on the micro LED structure 900 of FIG. 9. Similar to the micro LED structure 900 in FIG. 9, the micro LED structure 1000 includes a bottom conductive layer 1002, a light emitting layer 1006, a bottom dielectric layer 1004, a top conductive structure 1008, a conductive side arm 1010 having an inverted L shape, and an ohmic contact layer 1012 that is much narrower than the light emitting layer 1006 to form an ohmic contact point. In some embodiments, the light emitting layer 1006 comprises, from top to bottom, a first type semiconductor layer 1006-1, an active layer 1006-2, and a second type semiconductor layer 1006-3.

[0073]

[0084] As can be seen in FIG. 10, in some embodiments, the second type semiconductor layer 1006-3 includes a second type top semiconductor layer 1006-31 and a second type bottom semiconductor layer 1006-32. The second type bottom semiconductor layer 1006-32 extends outward relative to the second type top semiconductor layer 1006-31, so that the extended portion of the second type bottom semiconductor layer 1006-32 is used as the protruding top portion 1006-32-1. In some embodiments, the material of the second type top semiconductor layer 1006-31 and the material of the second type bottom semiconductor layer 1006-32 can be the same or different. In some embodiments, the second type top semiconductor layer 1006-31 is AlGaInP, and the second type bottom semiconductor layer 1006-32 is GaP. In addition, in some embodiments, the first type semiconductor layer 1006-1 has one layer or multiple layers. For example, the first-type semiconductor layer 1006-1 includes, from top to bottom, N-type AlInP and N-type GaAs. In another example, the first-type semiconductor layer 1006-1 includes only N-type AlInP. In some embodiments, the N-type AlInP is directly below and in contact with the ohmic contact layer 1012 and the upper conductive structure 1008. In one preferred embodiment, the light emitting layer 1006 includes, from top to bottom, N-type AlInP, a quantum active layer, P-type AlGaInP, and P-type GaP.

[0074]

[0085] As shown in FIG. 10, in some embodiments, the horizontal portion 1010-1 of the conductive side arm 1010 covers and is in direct contact with the bottom semiconductor layer 1006-32 of the second type, and the end of the horizontal portion 1010-1 is not directly connected to the top semiconductor layer 1006-31 of the second type, the active layer 1006-2, and / or the semiconductor layer 1006-1 of the first type. In some embodiments, the lateral width of the bottom conductive layer 1002 is greater than the lateral width of the bottom dielectric layer 1004. In some embodiments, the sidewalls of the bottom conductive layer 1002 protrude outward from the sidewalls of the conductive side arm 1010 (not shown in FIG. 10). In some embodiments, the material of the conductive side arm 1010 is a conductive metal or another conductive material.

[0075]

[0086] Similar to Figures 1-9, in some embodiments, there are two conductive side arms 1010 on either side of the micro LED structure 1000 of Figure 10. Additionally, similar to Figures 1-9, in some embodiments, the conductive side arms 1010 may be attached to and contact the side walls of the bottom dielectric layer 1004 of Figure 10. As an alternative embodiment, the shape of the conductive side arms 1010 may be changed to another shape without contacting the side walls of the bottom dielectric layer 1004 (not shown in Figure 10), and equivalent embodiments or variations may be realized by one skilled in the art.

[0076]

[0087] FIG. 11 is a cross-sectional view of a micro LED structure according to a ninth embodiment. The micro LED structure 1100 shown in FIG. 11 has a high light extraction efficiency. In some embodiments, the light extraction efficiency is at least 20%. In some embodiments, the light extraction efficiency is at least 30%. In some embodiments, the light extraction efficiency is at least 40%. In some embodiments, the light extraction efficiency is at least 50%. In some embodiments, the light extraction efficiency is at least 60%. In some embodiments, the light extraction efficiency is at least 70%. In some embodiments, the light extraction efficiency is at least 80%. In some embodiments, the light extraction efficiency is at least 90%. In some embodiments, the micro LED structure 1100 of FIG. 11 is based on the micro LED structure 1000 of FIG. 10. Similar to the micro LED structure 1000 in Figure 10, the micro LED structure 1100 includes a bottom conductive layer 1102, a light emitting layer 1106, a bottom dielectric layer 1104, a top conductive structure 1108, conductive side arms 1110 having an inverted L shape, and an ohmic contact layer 1112 that is much narrower than the light emitting layer 1106 to form an ohmic contact point. In some embodiments, the light emitting layer 1106 comprises, from top to bottom, a first type semiconductor layer 1106-1, an active layer 1106-2, and a second type semiconductor layer 1106-3. In some embodiments, the second type semiconductor layer 1106-3 includes a second type top semiconductor layer 1106-31 and a second type bottom semiconductor layer 1106-32.

[0077]

[0088] According to Fig. 11, the micro LED structure 1100 with high light extraction efficiency further comprises a transparent insulating layer 1114. In some embodiments, there are two transparent insulating layers 1114 on both sides of the micro LED structure 1100. In some embodiments, the transparent insulating layer 1114 directly covers at least a part of the gap, or alternatively, all of the gap between the conductive side arm 1110 and the sidewall of the light emitting layer 1106 at the protruding top 1106-32-1 of the second type bottom semiconductor layer 1106-32. The transparent insulating layer 1114 also directly covers at least a substantial part of the exposed sidewall of the second type top semiconductor layer 1106-31, the top and sidewall of the conductive side arm 1110 towards the micro LED structure 1100, the sidewall of the active layer 1106-2, and the sidewall of the first type semiconductor layer 1106-1. In some embodiments, a substantial portion of the sidewall of the first type semiconductor layer 1106-1 is at least 50% of the sidewall from bottom to top. In some embodiments, a substantial portion of the sidewall of the first type semiconductor layer 1106-1 is at least 70% of the sidewall from bottom to top. In some embodiments, a substantial portion of the sidewall of the first type semiconductor layer 1106-1 is at least 90% of the sidewall from bottom to top.

[0078]

[0089] In some embodiments, the upper conductive structure 1108 is disposed on the sidewalls and top of the ohmic contact layer 1112, the protruding top of the first type semiconductor layer 1106-1, and the top of the transparent insulating layer 1114. In some embodiments, the top of the transparent insulating layer 1114 covers at least a portion of the top of the first type semiconductor layer 1106-1 (not shown in FIG. 11), but does not cover the top of the ohmic contact layer 1112.

[0079]

[0090] In some embodiments, the material of the bottom conductive layer 1102 includes one or more types of conductive metals, such as Cr, Pt, Au, Sn, etc. The multi-layer composite conductive layer used as the bottom conductive layer 1102 is made of these metals. In some embodiments, the bottom conductive layer 1102 is further used as a bonding layer bonded to the surface of an electric circuit base 1116 (not shown in FIG. 11 ) so as to electrically connect the light emitting layer 1106 to the electric circuit base 1116. The electric circuit base 1116 includes at least a driving circuit for controlling the light emission of the light emitting layer 1106.

[0080]

[0091] In some embodiments, the bottom of the conductive side arm 1110 extends downward but does not contact the electrical circuitry base 1116. In some embodiments, when the bottom of the conductive side arm 1110 extends downward to contact the electrical circuitry base 1116, a contact electrode on the electrical circuitry base 1116 is connected to the bottom of the conductive side arm 1110 and other areas below the bottom of the conductive side arm 1110 that are not in contact with the contact electrode are insulated. In some embodiments, the bottom of the conductive side arm 1110 is also bonded onto a surface of the electrical circuitry base 1116.

[0081]

[0092] As described above in FIG. 1-FIG. 11, in the LED structure with high light extraction efficiency disclosed herein, the light emitting layer realizes downward electrical contact using the bottom conductive layer and realizes upward electrical contact using the top conductive structure. Furthermore, the conductive side arms electrically connect the sidewalls of the light emitting layer to both sides of the bottom conductive layer. When the bottom of the conductive side arms extends downward to contact the electric circuit base, the conductive side arms further electrically connect the light emitting layer to the electric circuit base, thereby increasing the light emitting area and improving the light extraction efficiency.

[0082]

[0093] In addition, the reflective area of ​​the composite reflective layer (bottom dielectric layer) is enlarged by using conductive side arms to electrically connect the sidewalls of the light-emitting layer and the bottom conductive layer, thereby further improving the light extraction efficiency of the LED.

[0083]

[0094] Moreover, the ohmic contact layer formed between the upper conductive structure and the light emitting layer can be very small and thin, such as a transparent metal film, which ensures good ohmic contact between the light emitting layer and the upper conductive structure, thereby increasing the light emission area and improving the light extraction efficiency.

[0084]

[0095] Although the detailed description includes many details, these should not be interpreted as limiting the scope of the present invention, but merely as illustrating different examples and aspects of the present invention. It should be understood that the scope of the present invention includes other embodiments not described in detail above. It is also possible to use micro LED structures and layers having different shapes and thicknesses, such as, for example, square bases or other polygonal bases. Various other modifications, changes, and variations that are apparent to those skilled in the art may be made in the arrangement, operation, and details of the methods and apparatus of the present invention disclosed herein without departing from the spirit and scope of the present invention as defined in the appended claims. Therefore, the scope of the present invention should be determined by the appended claims and their legal equivalents.

[0085]

[0096] Further embodiments include various subsets of the above embodiments, including those illustrated in Figures 1-11, combined or otherwise reconfigured with various other embodiments.

[0086]

[0097] 12 is a top view of a micro LED display panel 1200 according to some embodiments. The display panel 1200 includes a data interface 1210, a control module 1220, and a pixel area 1250. The data interface 1210 receives data defining an image to be displayed. The source and format of this data can vary depending on the application. The control module 1220 receives the input data and converts it into a form suitable for driving pixels of the display panel. The control module 1220 may include a scan controller including digital logic and / or state machines to convert the received format into a format suitable for the pixel area 1250, shift registers or other types of buffers and memories to store and transfer data, digital to analog converters and level shifters, and clock circuits.

[0087]

[0098] The pixel area 1250 includes an array of pixels. The pixels include micro LEDs, such as the micro LED 1234 having the structure described in Figures 1-11, and in some examples are integrated with a pixel driver. In this example, the display panel 1200 is a color RGB display panel. The display panel includes red, green, and blue pixels. Within each pixel, the LED 1234 is controlled by a pixel driver. The pixels are in contact with a supply voltage (not shown) and with ground via a ground pad 1236, according to some embodiments, and also with a control signal. Although not shown in Figure 12, the p-electrode of the LED 1234 is electrically connected to the output of the drive transistor. The LED current drive signal connection (between the p-electrode of the LED and the output of the pixel driver), the ground connection (between the n-electrode and system ground), the supply voltage Vdd connection (between the source of the pixel driver and system Vdd), and the control signal connection to the gate of the pixel driver are made according to various embodiments.

[0088]

[0099] FIG. 12 is a representative diagram only. Other designs will be apparent. For example, the colors need not be red, green, and blue. Nor need they be arranged in columns or stripes. As an example, away from the square matrix arrangement of pixels shown in FIG. 12, a hexagonal matrix arrangement of pixels could be used to form the display panel 1200.

[0089]

[0100] In some applications, a fully programmable rectangular array of pixels is not necessary. Other designs of display panels with a wide variety of shapes and displays can also be formed using the device structures described herein. One class of examples is specialized applications, including signage and automotive applications. For example, multiple pixels can be arranged in a star or spiral shape to form a display panel, and different patterns can be generated on the display panel by turning LEDs on and off. Another specialized example is automobile headlights and smart lighting, where certain pixels are grouped together to form various lighting shapes, and each group of LEDs can be turned on and off or otherwise adjusted by individual pixel drive circuits.

[0090]

[0101] Different types of display panels can be made. For example, the resolution of a display panel can typically range from 8x8 to 3840x2160. Common display resolutions include QVGA with a resolution of 320x240 and an aspect ratio of 4:3, XGA with a resolution of 1024x768 and an aspect ratio of 4:3, D with a resolution of 1280x720 and an aspect ratio of 16:9, FHD with a resolution of 1920x1080 and an aspect ratio of 16:9, UHD with a resolution of 3840x2160 and an aspect ratio of 16:9, and 4K with a resolution of 4096x2160. There can also be a wide variety of pixel sizes ranging from submicron to over 100mm. The size of the total display area can also vary widely, from as little as a diagonal of tens of microns or less to over hundreds of inches.

[0091]

[0102] Example applications include display screens, home / office projectors and portable electronics such as smartphones, laptops, wearable electronics, AR and VR glasses, as well as light engines for retinal projection. Power consumption can vary from a few milliwatts for retinal projectors to several kilowatts for large screen outdoor displays, projectors, and smart car headlights. In terms of frame rate, due to the fast response (nanoseconds) of inorganic LEDs, frame rates can be KHz or even MHz at lower resolutions.

[0092]

[0103] Further embodiments include various subsets of the above embodiments, including the embodiments shown in Figures 1-12 combined with various other embodiments or rearranged in other ways.

[0093]

[0104] Although the detailed description includes many details, these should not be interpreted as limitations on the scope of the present invention, but merely as illustrative of different examples and aspects of the present invention. It should be understood that the scope of the present invention includes other embodiments not described in detail above. For example, the above-described techniques can also be applied to the integration of functional devices other than LEDs and OLEDs with control circuits other than pixel drive circuits. Examples of non-LED devices include vertical cavity surface emitting lasers (VCSELs), photodetectors, microelectromechanical systems (MEMS), silicon photonic devices, power electronic devices, and distributed feedback lasers (DFBs). Examples of other control circuits include current drive circuits, voltage drive circuits, transimpedance amplifiers, and logic circuits.

[0094]

[0105] The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the embodiments described herein and variations thereof. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the subject matter disclosed herein. Thus, the present disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.

[0095]

[0106] Features of the present invention may be implemented in, using, or with the aid of a computer program product, such as a storage medium or computer-readable storage medium having instructions stored thereon that can be used to program a processing system to perform any of the features presented herein. The storage medium may include high-speed random access memory, such as, but not limited to, DRAM, SRAM, DDR RAM, or other random access solid-state memory devices, and may include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices. The memory optionally includes one or more storage devices located remotely from the CPU. The memory, or alternatively, the non-volatile memory devices within the memory, include non-transitory computer-readable storage media.

[0096]

[0107] When stored on any machine-readable medium, features of the present invention may be embodied in software and / or firmware to control the hardware of a processing system and to enable the processing system to utilize the results of the present invention and interact with other mechanisms. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0097]

[0108] Although the terms "first," "second," etc. may be used herein to describe various elements, it will be understood that these elements or steps should not be limited by these terms. These terms are used only to distinguish one element or step from another element or step.

[0098]

[0109] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the claims. When used in the description of the embodiments and in the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or," when used herein, refers to and includes any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms "comprise" and / or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0099]

[0110] The above description, for purposes of illustration, has been set forth with reference to specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the scope of the claims to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of operation and practical application, thereby enabling others skilled in the art to do so.

Claims

1. A micro light emitting diode with high light extraction efficiency, a bottom conductive layer; a light emitting layer on the bottom conductive layer; an upper conductive structure on the light emitting layer; a bottom dielectric layer disposed between the bottom conductive layer and the light emitting layer; and a conductive side arm connecting a sidewall of the bottom layer of the light emitting layer and the bottom conductive layer.

2. 10. The micro light-emitting diode of claim 1, further comprising an ohmic contact layer disposed between the upper conductive structure and the light-emitting layer.

3. The micro light emitting diode of claim 2 , wherein the lateral width of the ohmic contact layer is much narrower than the lateral width of the light emitting layer.

4. The micro light-emitting diode according to claim 2 or 3, wherein the upper conductive structure directly covers the ohmic contact layer, and a substantial portion of the light-emitting layer is not shielded by the ohmic contact layer.

5. The micro light-emitting diode according to any one of claims 2 to 4, wherein the ohmic contact layer is a metal film.

6. The micro light-emitting diode according to any one of claims 2 to 5, wherein the thickness of the ohmic contact layer is less than 20 nm, and the lateral width of the ohmic contact layer is less than 0.5 μm.

7. The micro light-emitting diode of any one of claims 2 to 6, wherein the material of the ohmic contact layer comprises at least one or more selected from the group consisting of metals of Groups I, II, III, IV, VI, and VIII of the periodic table.

8. The micro light-emitting diode according to any one of claims 2 to 7, wherein the upper conductive structure is transparent and the ohmic contact layer is transparent.

9. The micro light-emitting diode according to any one of claims 1 to 8, wherein the bottom dielectric layer is a composite reflective layer.

10. 10. The micro light-emitting diode of claim 9, wherein the composite reflective layer includes a plurality of layers, including at least an insulating reflective dielectric layer and a composite metal reflective layer, the composite metal reflective layer being disposed on the bottom of the insulating reflective dielectric layer and contacting the bottom conductive layer.

11. The micro light emitting diode of claim 10 , wherein the composite metal reflective layer has multiple layers.

12. The micro light-emitting diode of claim 10 or 11, wherein the insulating reflective dielectric layer further comprises a top insulating dielectric layer and a bottom Bragg mirror.

13. The micro light-emitting diode of claim 12 , wherein the upper insulating dielectric layer has three or more layers.

14. The micro light-emitting diode according to claim 12 or 13, wherein the material of the upper insulating dielectric layer is a metal oxide.

15. The micro light-emitting diode of any one of claims 1 to 14, wherein the lateral width of the bottom conductive layer is greater than the lateral width of the bottom dielectric layer, such that the bottom conductive layer has a protruding top extending outside the bottom dielectric layer, one end of the conductive side arm is connected to the bottom layer of the light-emitting layer, and at least a portion of another end of the conductive side arm is connected to and supported on the protruding top of the bottom conductive layer.

16. The micro light-emitting diode of any one of claims 1 to 15, wherein the lateral width of the bottom dielectric layer is equal to or greater than the width of the bottom of the light-emitting layer.

17. the light emitting layer further comprises, in order from top to bottom, a first type semiconductor layer, an active layer, and a second type semiconductor layer; the second-type semiconductor layer has a protruding upper portion extending outside the active layer and the first-type semiconductor layer; The micro light-emitting diode of any one of claims 1 to 16, wherein one end of the conductive side arm covers and contacts the protruding top of the second type semiconductor layer, and another end of the conductive side arm contacts the bottom conductive layer.

18. a lateral width of the bottom conductive layer is greater than a lateral width of the second type semiconductor layer and a lateral width of the bottom dielectric layer, such that the bottom conductive layer has a protruding top portion extending outside the second type semiconductor layer and the bottom dielectric layer; 20. The micro light emitting diode of claim 17, wherein at least a portion of the conductive side arm is supported on the protruding top of the bottom conductive layer.

19. 20. The micro light emitting diode of claim 18, wherein the lateral width of the bottom conductive layer is less than 2 μm.

20. 20. The micro light-emitting diode of claim 18 or 19, wherein the width of the protruding top of the bottom conductive layer is less than or equal to the width of the protruding top of the second type semiconductor layer.

21. 21. The micro light emitting diode of claim 17, wherein the second type semiconductor layer further comprises a second type top semiconductor layer and a second type bottom semiconductor layer, the second type bottom semiconductor layer extending outward relative to the second type top semiconductor layer, thereby forming a protruding top.

22. 22. The micro light emitting diode of claim 21, wherein the material of the top semiconductor layer of the second type is different from the material of the bottom semiconductor layer of the second type.

23. 23. The micro light-emitting diode of claim 21 or 22, wherein the top semiconductor layer of the second type is AlGaInP, the bottom semiconductor layer of the second type is GaP, and the first type semiconductor layer is AlInP.

24. The end of the conductive side arm is in electrical contact with the protruding top portion of the second-type bottom semiconductor layer; is not in electrical contact with the second-type upper semiconductor layer; The micro light emitting diode of any one of claims 21 to 23, wherein the light emitting layer and the first type semiconductor layer are not in electrical contact.

25. The micro light emitting diode of any one of claims 17 to 24, wherein the lateral width of the first type semiconductor layer is equal to or greater than the lateral width of the active layer.

26. The micro light emitting diode of any one of claims 17 to 24, wherein the lateral width of the first type semiconductor layer is much narrower than the lateral width of the active layer.

27. The micro light-emitting diode of any one of claims 1 to 26, wherein the conductive side arm has an inverted L-shape.

28. The micro light emitting diode according to any one of claims 1 to 27, wherein the conductive side arms are attached and connected to sidewalls of the bottom dielectric layer.

29. 29. The micro light emitting diode of any one of claims 1 to 28, wherein the lateral width of the bottom conductive layer is greater than the lateral width of the bottom dielectric layer, and the sidewalls of the bottom conductive layer protrude outwardly and beyond the sidewalls of the conductive side arms.

30. a transparent insulating layer covering at least the protruding top of the second-type semiconductor layer, the top and sidewalls of the conductive side arms, the sidewalls of the light emitting layer, and the sidewalls of the first-type semiconductor layer; The micro light-emitting diode according to any one of claims 17 to 29, wherein the upper conductive structure is disposed on top of the transparent insulating layer.

31. The micro light-emitting diode according to any one of claims 1 to 30, wherein the material of the conductive side arms is a conductive metal.

32. The micro light-emitting diode of any one of claims 17 to 31, wherein the first type semiconductor layer is an N-type semiconductor layer and the second type semiconductor layer is a P-type semiconductor layer.

33. The micro light-emitting diode of any one of claims 17 to 31, wherein the first type semiconductor layer is a P-type semiconductor layer and the second type semiconductor layer is an N-type semiconductor layer.

34. The micro light-emitting diode according to any one of claims 1 to 33, wherein the material of the bottom conductive layer comprises one or more types of conductive metals.

35. The micro light-emitting diode of any one of claims 1 to 34, further comprising an electrical circuit base on the bottom of the bottom conductive layer, the bottom conductive layer being used as a bonding layer bonded to the surface of the electrical circuit base.

36. 36. The micro light-emitting diode of claim 35, wherein the electrical circuit base comprises at least a drive circuit for controlling the emission of the light-emitting layer.

37. The micro light-emitting diode according to any one of claims 1 to 36, wherein the micro light-emitting diode has a light extraction efficiency of at least 20%.

38. The micro light-emitting diode according to any one of claims 1 to 36, wherein the micro light-emitting diode has a light extraction efficiency of at least 40%.

39. The micro light-emitting diode according to any one of claims 1 to 36, wherein the micro light-emitting diode has a light extraction efficiency of at least 60%.

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