CN117334809A - Micro display unit and display device - Google Patents

Abstract

The invention relates to a micro display unit and display equipment, wherein the micro display unit comprises a first light emitting unit and a second light emitting unit which are bonded through a first bonding layer, the first light emitting unit and the second light emitting unit respectively comprise a first semiconductor layer, a light emitting layer and a second semiconductor layer which are laminated in sequence, and the second semiconductor layer of the first light emitting unit and/or the second semiconductor layer of the second light emitting unit comprises a gallium nitride layer and a transition layer which are laminated in sequence.

Description

Micro display unit and display device

Technical Field

The invention relates to the field of semiconductor display, in particular to a micro display unit and display equipment.

Background

Micro light emitting diodes (Micro light emitting diode, abbreviated as Micro LEDs) are generally LED devices that reduce the size of LED chips to micrometer sizes based on conventional LED chip structures. By arranging Micro LEDs of three colors of red, green and blue on a thin film transistor (Thin Film Transistor, TFT for short) or a complementary metal oxide semiconductor (Complementary Metal Oxide Semiconductor, CMOS for short) according to a certain rule, a Micro device capable of realizing full color display is formed.

The micro light emitting diode chip has a small size, is used for displaying the characteristics of high integration level, self-luminescence, high stability and the like, has larger advantages in terms of brightness, resolution, contrast, energy consumption, service life, response speed, thermal stability and the like compared with a liquid crystal display (Liquid Crystal Display, LCD), but still faces a plurality of difficulties when forming a pixel unit by stacking the micro light emitting diodes.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a micro display unit and a display device with the micro display unit, which can effectively improve the performance of a micro light emitting diode when the micro light emitting diode is used as a light emitting device. The technical problems to be solved by the invention are realized by adopting the following technical scheme:

a microdisplay unit comprising: the LED light-emitting device comprises a first light-emitting unit and a second light-emitting unit which are arranged in opposite directions, wherein each of the first light-emitting unit and the second light-emitting unit comprises a first semiconductor layer, a light-emitting layer and a second semiconductor layer which are sequentially stacked, the light-emitting layer is positioned between the first semiconductor layer and the second semiconductor layer, the first light-emitting unit is bonded with the second light-emitting unit through the first layer, the second semiconductor layer of the first light-emitting unit and/or the second semiconductor layer of the second light-emitting unit comprises a gallium nitride layer and a transition layer which are sequentially stacked, the gallium nitride layer is positioned on the light-emitting layer, the transition layer is positioned on the gallium nitride layer, a conducting layer is arranged on the transition layer, the first bonding layer is positioned on the conducting layer, one side of the conducting layer faces the first bonding layer, and the other side of the conducting layer faces the conducting layer, and the other side of the conducting layer faces the transition layer.

Optionally, the transition layer is an indium gallium nitride layer.

Optionally, the indium gallium nitride layer gradually decreases from a position close to the conductive layer to a position far away from the conductive layer.

Optionally, the indium gallium nitride layer has the same indium content at different positions at the same distance from the conductive layer along the thickness direction.

Optionally, the indium content in the conductive layer has a highest value point along the thickness direction, where the highest value point is located on the front surface of the conductive layer, or the highest value point is located on the back surface of the conductive layer, or the highest value point is located between the front surface of the conductive layer and the back surface of the conductive layer.

Optionally, the conductive layer has the same indium content along the same horizontal position at the highest value point.

Optionally, the indium content of the conductive layer increases and decreases from the front surface of the conductive layer to the back surface of the conductive layer in the thickness direction.

Optionally, the indium content of different positions of the conductive layer, which are at the same distance from the front surface of the conductive layer in the thickness direction, is the same.

Optionally, the contact electrode is in point contact with the highest indium content value in the conductive layer.

Optionally, the back surface of the conductive layer and the surface of the transition layer facing the back surface of the conductive layer have the same indium content.

Optionally, a surface of the conductive layer, which is in contact with the first adhesive layer, is roughened.

The invention also provides a display device having a micro display unit as claimed in any one of claims 1 to 11.

The first light-emitting unit and the second light-emitting unit are bonded through the first bonding layer, so that the micro display unit is converted from a tiling scheme to a stacking scheme, the occupied area of each light-emitting unit is reduced, and the transfer workload of the stacking scheme is one third of that of the tiling scheme under the condition of the same pixel density, so that the workload and the process time are greatly reduced; the second semiconductor layer is arranged to comprise a gallium nitride layer and a transition layer which are sequentially laminated, the transition layer is provided with a conductive layer, the conductive layer is in contact with the contact electrode, current firstly expands on the conductive layer, then flows through the gallium nitride layer after passing through the transition layer and is subjected to composite luminescence with electrons in the luminescent layer, and current expansion and luminous efficiency are improved.

Drawings

Fig. 1 to 3 are schematic views of a display device provided by the present invention;

FIGS. 4 and 5 are schematic diagrams of prior art microdisplay units employing tiling schemes;

FIG. 6 is a schematic diagram of a prior art microdisplay unit employing a stacking scheme;

fig. 7 to 10 are cross-sectional views of micro-display units according to various embodiments of the present invention.

Detailed Description

The micro display unit and the display device provided by the present invention will be described in more detail with reference to the accompanying drawings, in which preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Accordingly, the following description is to be construed as broadly known to those skilled in the art and not as limiting the invention. In addition, in the drawings, the width, length, thickness, and the like of each member may be exaggerated for convenience of explanation. When it is described that one component is located "on" or "upper" of another component, it is not only the case where each component is located "directly" on "or" upper "of another component, but also the case where another component is interposed between each component and another component. Like reference numerals refer to like parts throughout the specification.

Fig. 1 to 3 show that the micro display unit described in the following embodiments may be used on any display device having display requirements, such as a palm top computer, a computer monitor containing an embedded computer, a computer monitor not containing an embedded computer, a tablet, a mobile phone, a media player or other handheld or portable electronic device, a wristwatch device, a hanging device, a headset or earpiece device, a device embedded in glasses or other device worn on the head of a user, or other wearable or micro device, a display, a computer display containing an embedded computer, a computer display not containing an embedded computer, a game device, a navigation device, an audio device, a video device, etc. The display device may have the shape of a wristwatch or glasses as shown in fig. 1-3, may form an outer shell having the shape of a helmet, or may have other configurations for helping to mount and secure components of one or more displays on or near the user's head.

Fig. 4 is a schematic diagram of a conventional microdisplay unit employing a tiling scheme, as shown in fig. 4, in which the conventional microdisplay unit typically uses light emitting units 20 (i.e., pixels) arranged on a display substrate 10 to display multiple images, each light emitting unit 20 includes at least a first light emitting unit 30 and a second light emitting unit 40 (i.e., sub-pixels), and the first light emitting unit 30 and the second light emitting unit 40 can emit light of the same color or emit light of different colors, and when the same color is emitted, the light can be blue light, or green light, or red light, and when the light of different colors is emitted, the light can be emitted, for example, blue light, green light, or blue light, red light, or green light, red light, respectively.

In order to realize full color display, as shown in fig. 5, each light emitting unit 20 may further include a third light emitting unit 50 (sub-pixel), and the first, second, and third light emitting units 30, 40, and 50 may emit light of different colors, for example, blue, green, and red light, respectively, and each light emitting unit 20 may emit light of different colors through the first, second, and third light emitting units 30, 40, and 50 to display a plurality of colors, and then display an image through a combination of the light emitting units 20.

The prior art tiles the first light emitting unit 30, the second light emitting unit 40, or the first light emitting unit 30, the second light emitting unit 40, and the third light emitting unit 50 on the display substrate 10, which results in each pixel occupying a larger area, and in the manufacturing process, when each sub-pixel is transferred to the display substrate, the workload and the process time are increased, the cost is high, and particularly when the sub-pixel area is further reduced, the transfer workload is huge.

As shown in fig. 6, the stacking scheme stacks the first light emitting unit 30, the second light emitting unit 40 of fig. 4, or the first light emitting unit 30, the second light emitting unit 40, and the third light emitting unit 50 of fig. 5 in a vertical direction to form one light emitting unit 20, and transfers each light emitting unit 20 to the display substrate 10. The stacking scheme greatly reduces the area occupied by each light emitting unit 20 compared with the tiling scheme, and the stacking scheme transfers one third of the workload and process time of the tiling scheme with the same pixel density, thereby having advantages in that the stacking scheme stacks the first light emitting unit 30, the second light emitting unit 40, or the first light emitting unit 30, the second light emitting unit 40, and the third light emitting unit 50 into a single light emitting unit 20, still faces a number of technical difficulties.

In the following embodiments, the present invention is described in terms of the light emitting unit 20 including the first light emitting unit 30 and the second light emitting unit 40, and it should be noted that all embodiments of the present invention are applicable to a case where the light emitting unit 20 includes the first light emitting unit 30, the second light emitting unit 40 and the third light emitting unit 50.

Fig. 7 is a cross-sectional view of the light-emitting unit 20, as shown in fig. 7, the light-emitting unit 20 includes the first light-emitting unit 30 and the second light-emitting unit 40 which are disposed opposite to each other, the first light-emitting unit 30 includes the first semiconductor layer 31, the light-emitting layer 33, and the second semiconductor layer 35 which are sequentially stacked, the light-emitting layer 33 is disposed between the first semiconductor layer 31 and the second semiconductor layer 35, the second light-emitting unit 40 includes the first semiconductor layer 41, the light-emitting layer 43, and the second semiconductor layer 45 which are sequentially stacked, the light-emitting layer 43 is disposed between the first semiconductor layer 41 and the second semiconductor layer 45, the first light-emitting unit 30 is bonded to the second light-emitting unit 40 through the first bonding layer 61, the first bonding layer 61 is disposed between the second semiconductor layer 35 of the first light-emitting unit 30 and the first semiconductor layer 41 of the second light-emitting unit 40, the second semiconductor layer 35 includes the gallium nitride layer 351 and the transition layer 353 which are sequentially stacked, the gallium nitride layer 351 is disposed on the light-emitting layer 33, the transition layer 353 is disposed on the gallium nitride layer 351, the conductive layer 51 is disposed on the transition layer 353, the first bonding layer 61 is disposed on the conductive layer 51, the conductive layer 51 is disposed on the surface facing the conductive layer 51, and the first bonding layer 511 is the conductive layer 51.

The first light emitting unit 30 and the second light emitting unit 40 are bonded through the first bonding layer 61, so that the micro display unit is converted from a tiling scheme to a stacking scheme, the occupied area of each light emitting unit 20 is reduced, and the transfer workload of the stacking scheme is one third of that of the tiling scheme under the condition of the same pixel density, and the workload and the process time are greatly reduced; the second semiconductor layer 35 is provided to include a gallium nitride layer 351 and a transition layer 353 which are sequentially stacked, the transition layer 353 is provided with a conductive layer 51, the conductive layer 51 is in contact with a contact electrode, current firstly expands on the conductive layer, then flows through the gallium nitride layer 351 after passing through the transition layer 353, and is combined with electrons in the light emitting layer 33 to emit light, so that current expansion and light emitting efficiency are improved.

In this embodiment, the light emitting unit 20 emits light in a direction perpendicular to the display substrate 10, and the light emitted from the first light emitting unit 30 near the display substrate 10 is directed to the second light emitting unit 40 so as to be observed by human eyes, and the light emitted from the first light emitting unit 30 passes through the second light emitting unit 40.

In this embodiment, the first light emitting unit 30 and the second light emitting unit 40 may be micro light emitting diodes, for example, having an area of about 500×500 micrometers, 300×300 micrometers, 200×200 micrometers, 150×150 micrometers, 120×120 micrometers, 100×100 micrometers, 80×80 micrometers, 50×50 micrometers, 20×20 micrometers, 10×10 micrometers, 5×5 micrometers to 500×500 micrometers, or any desired area greater than 500×500 micrometers or less than 5×5 micrometers.

In other embodiments, the micro light emitting diode may have a rectangular, hexagonal, octagonal, circular, oval, or other shape structure with similar areas.

In this embodiment, the first and second light emitting units 30 and 40 may emit blue light, green light, or blue light, red light, or green light, blue light, or green light, red light, or red light, blue light, or red light, green light, respectively.

In other embodiments, the first and second light emitting units 30 and 40 each emit blue light, or green light, or red light.

In this embodiment, the wavelength ranges of red light, blue light and green light are 600-660nm, 440-480nm and 490-570nm, respectively.

In the present embodiment, the red light emitting material may be one or more of GaAs, gaP, alGaAs, gaAsP, alGaInP, but is not limited thereto.

In the present embodiment, the blue light emitting material may be one or more of GaN, inGaN, alInGaN, but is not limited thereto.

In the present embodiment, the green light emitting material may be one or more of GaN, inGaN, alInGaN, gaAs, gaP, alGaInP, alGaP, but is not limited thereto.

In this embodiment, the first semiconductor layers 31 and 41 may be N-type semiconductor layers having an N-type doping concentration, the light emitting layers 33 and 43 may be active quantum well layers, may be single-layer quantum well layers or multi-layer quantum well layers, the second semiconductor layers 35 and 45 may be P-type semiconductor layers having a P-type doping concentration, the N-type semiconductor layers and the P-type semiconductor layers are respectively connected with electrodes, electrons generated by the N-type semiconductor layers and holes generated by the P-type semiconductor layers after the electrodes are connected with a power supply are combined to emit light in the active quantum well layers, the light emitting wavelength is within a set or selected range, such as blue light with a wavelength range of 440-480nm, green light with a wavelength range of 490-570nm, red light with a wavelength range of 600-660 nm.

In other embodiments, the first semiconductor layers 31 and 41 may be P-type semiconductor layers having a P-type doping concentration, the light emitting layers 33 and 43 may be active quantum well layers, single quantum well layers or multi-quantum well layers, the second semiconductor layers 35 and 45 may be N-type semiconductor layers having an N-type doping concentration, the N-type semiconductor layers and the P-type semiconductor layers are respectively connected to electrodes, electrons generated by the N-type semiconductor layers and holes generated by the P-type semiconductor layers after the electrodes are connected to a power source are combined to emit light in the active quantum well layers, the light emitting wavelength is within a set or selected range, such as blue light with a wavelength range of 440-480nm, green light with a wavelength range of 490-570nm, red light with a wavelength range of 600-660 nm.

In this embodiment, the first semiconductor layers 31 and 41, the light emitting layers 33 and 43, and the second semiconductor layers 35 and 45 are formed by a Metal Organic Chemical Vapor Deposition (MOCVD) method, a molecular beam epitaxy (MBE, or the like) method, or the like.

In the present embodiment, the first light emitting unit 30 and the second light emitting unit 40 have a thickness, for example, the thickness of the first light emitting unit 30 is 0.5 micrometers to 10 micrometers, and the thickness of the second light emitting unit 40 is 0.5 micrometers to 8 micrometers.

In this embodiment, the first semiconductor layers 31, 41 have a thickness of 0.1 μm to 5 μm, the light emitting layers 33, 43 have a thickness of 0.01 μm to 2 μm, and the second semiconductor layers 35, 45 have a thickness of 0.01 μm to 3 μm.

In the present embodiment, the first adhesive layer 61 is disposed between the second semiconductor layer 35 of the first light emitting unit 30 and the first semiconductor layer 41 of the second light emitting unit 40.

In other embodiments, as shown in fig. 8, the first adhesive layer 61 may be disposed between the first semiconductor layer 31 of the first light emitting unit 30 and the second semiconductor layer 45 of the second light emitting unit 40, or between the first semiconductor layer 31 of the first light emitting unit 30 and the first semiconductor layer 41 of the second light emitting unit 40, or between the second semiconductor layer 35 of the first light emitting unit 30 and the second semiconductor layer 45 of the second light emitting unit 40.

In this embodiment, the first adhesive layer 61 is a transparent optical adhesive (OCA), and may be epoxy, polyimide, SU8, spin-on glass (SOG), benzocyclobutene (BCB), or the like.

OCA optical cement (Optically Clear Adhesive) is a special adhesive for transparent optical elements, mainly comprises the steps of preparing optical acrylic cement into a non-base material, then respectively attaching a release film on an upper bottom layer and a lower bottom layer to form the non-base material high-transmittance double-sided adhesive cement, and has the advantages of high cleanliness, high light transmittance, low haze, high adhesive force, no crystal point, no bubbles, water resistance, high temperature resistance, ultraviolet resistance and the like. The problems of yellowing, aging, fogging, detachment from the adhered surface, bubble generation and the like can not be generated after long-time use.

In this embodiment, the first adhesive layer 61 has a thickness of 0.2 μm to 10. Mu.m.

In this embodiment, the second semiconductor layer 35 of the first light emitting unit 30 includes a gallium nitride layer 351 and a transition layer 353 sequentially stacked, the gallium nitride layer 351 is located on the light emitting layer 33, the transition layer 353 is located on the gallium nitride layer 351, the conductive layer 51 is disposed on the transition layer 353, and the first adhesive layer 61 is located on the conductive layer 51.

In other embodiments, as shown in fig. 8, the first adhesive layer 61 is disposed between the first semiconductor layer 31 of the first light emitting unit 30 and the second semiconductor layer 45 of the second light emitting unit 40, the second semiconductor layer 45 of the second light emitting unit 40 includes a gallium nitride layer 451 and a transition layer 453 sequentially stacked, the gallium nitride layer 451 is disposed on the light emitting layer 43, the transition layer 453 is disposed on the gallium nitride layer 451, the conductive layer 71 is disposed on the transition layer 453, and the first adhesive layer 61 is disposed on the conductive layer 71.

In other embodiments, as shown in fig. 9, the first adhesive layer 61 is disposed between the second semiconductor layer 35 of the first light emitting unit 30 and the second semiconductor layer 45 of the second light emitting unit 40; the second semiconductor layer 35 of the first light emitting unit 30 includes a gallium nitride layer 351 and a transition layer 353 stacked in this order, the gallium nitride layer 351 being on the light emitting layer 33, the transition layer 353 being on the gallium nitride layer 351, the transition layer 353 being provided with a conductive layer 51; the second semiconductor layer 45 of the second light emitting unit 40 includes a gallium nitride layer 451 and a transition layer 453 stacked in this order, the gallium nitride layer 451 is located on the light emitting layer 43, the transition layer 453 is located on the gallium nitride layer 451, the conductive layer 71 is provided on the transition layer 453, and the first adhesive layer 61 is located between the conductive layer 51 and the conductive layer 71.

In the present embodiment, the conductive layer 51 includes Transparent Conductive Oxide (TCO), such as tin oxide (SnO), indium oxide (InO 2), zinc oxide (ZnO), indium Tin Oxide (ITO), and Indium Tin Zinc Oxide (ITZO), but is not limited thereto.

In this embodiment, the thickness of the conductive layer 51 is 0.01 micrometers to 2 micrometers.

Preferably, the transition layer 353 is an indium gallium nitride layer (In _X Ga _(1-X) N, where X represents the indium content and has a value of from 0.005 to 0.30), and the indium gallium nitride layer is formed by passing an indium source, which may be trimethylindium (TMIn), in the growth of the gallium nitride layer.

When indium is contained in the conductive layer 51, an indium gallium nitride layer is provided between the gallium nitride layer 351 and the conductive layer 51, so that the conductive layer 51 can better cover the second semiconductor layer 35, the conductive layer 51 is connected with the contact electrode, current is expanded through the conductive layer 51, indium is contained in the contact interface between the conductive layer 51, the second semiconductor layer 35 and the conductive layer 51 and the second semiconductor layer 35, and the current can better flow from the conductive layer 51 to the second semiconductor layer 35, thereby improving luminous efficiency.

As a further preferred example, the indium content of the ingan layer gradually decreases from a position close to the conductive layer 51 to a position far from the conductive layer 51, i.e., the indium content of the transition layer 353 gradually decreases from top to bottom in fig. 7.

The indium content of the indium gallium nitride layer is gradually reduced from a position close to the conductive layer 51 to a position far away from the conductive layer 51, at this time, the difference between the indium content in the indium gallium nitride layer and the indium content in the conductive layer 51 is smaller, which is beneficial to current flowing from the conductive layer 51 to the indium gallium nitride layer, after that, the indium content is gradually reduced, the difference between the indium content in the indium gallium nitride layer and the indium content in the gallium nitride layer 351 is gradually reduced, and the current is injected into the gallium nitride layer 351 after passing through the indium gallium nitride layer and generates holes in the gallium nitride layer 351.

As a further preferred example, the indium content of the indium gallium nitride layer is the same at different positions at the same distance from the conductive layer 51 in the thickness direction, i.e., the indium content of the transition layer 353 is the same or substantially the same at the same horizontal position in fig. 7.

The indium content in the indium gallium nitride layer is set to be the same or basically the same along the same horizontal direction, and when current flows along the longitudinal direction, the uniform expansion on the same horizontal section is ensured, and the luminous uniformity is improved.

As a further preferred embodiment, the indium content of the conductive layer 51 has a highest value point in the thickness direction.

The conductive layer 51 contacts with the contact electrode, and the current spreads at the contact surface of the conductive layer 51 and the contact electrode, so that the indium content in the conductive layer 51 is set to a highest value point along the thickness direction, and the current can sufficiently spread along the transverse direction at the highest value point and then flows along the longitudinal direction.

The highest point may be located on the front surface 511 of the conductive layer, where the contact electrode is disposed on the front surface 511 of the conductive layer and contacts the front surface 511 of the conductive layer, and the indium content in the conductive layer 51 is in a tendency of changing in an inclined straight line or parabola.

The highest point may also be located on the back 513 of the conductive layer, where the contact electrode is disposed on the back 513 of the conductive layer and contacts the back 513 of the conductive layer, and the indium content in the conductive layer 51 is in a tendency of changing in an inclined straight line or parabola.

The highest point may also be located between the front surface 511 of the conductive layer and the back surface 513 of the conductive layer, where the contact electrode is disposed between the front surface 511 of the conductive layer and the back surface 513 of the conductive layer and contacts the highest point of the indium content in the conductive layer 51, and the indium content in the conductive layer 51 is in a conical fold line or a normal curve trend and has a highest point.

When the highest value is located between the front surface 511 and the back surface 513 of the conductive layer, the indium content of the conductive layer 51 from the front surface 511 of the conductive layer to the back surface 513 of the conductive layer increases and decreases, so that the current can be ensured to be fully spread in the horizontal direction or the transverse direction, and then flows to the transition layer 353 and the gallium nitride layer 351 in the vertical direction or the longitudinal direction.

As a further preferred embodiment, the conductive layer 51 has the same or substantially the same indium content along the same horizontal position at the highest value point.

Setting the indium content of the conductive layer 51 to be the same or substantially the same along the same horizontal position at the highest value point described above can ensure uniform spreading of the current along the same horizontal position.

As a further preferred example, the conductive layer 51 has the same indium content at different positions at the same distance from the conductive layer front surface 511 in the thickness direction.

The same indium content at different locations of the conductive layer 51 at the same distance from the front surface 511 of the conductive layer in the thickness direction ensures that the current is uniformly distributed on the same cross section at different points in time when flowing in the vertical direction or the longitudinal direction.

As a further preferred example, the conductive layer back surface 513 has the same indium content as the transition layer 353 on the surface facing the conductive layer back surface 513.

Setting the indium content of the conductive layer back surface 513 to be the same or substantially the same as that of the transition layer 353 toward the conductive layer back surface 513 can reduce the influence of the contact interface on the current flow direction and make the current distribution more uniform on the contact interface.

As a further preferred example, the surface of the conductive layer 51 contacting the first adhesive layer 61 is roughened.

Roughening the surface of the conductive layer 51 in contact with the first adhesive layer 61 can improve the adhesive strength, the luminous strength, and the current spreading on the conductive layer 51.

Fig. 10 shows an embodiment in which the light emitting unit 20 includes the first, second, and third light emitting units 30, 40, and 50, and as shown in fig. 10, the third light emitting unit 50 includes a first semiconductor layer 51, a light emitting layer 53, and a second semiconductor layer 55 stacked in this order, with the light emitting layer 53 being located between the first and second semiconductor layers 51 and 55. The light emitting unit 20 emits light in a direction perpendicular to the display substrate 10, and the light emitting direction is emitted from the first light emitting unit 30 adjacent to the display substrate 10 to the third light emitting unit 50 so as to be observed by human eyes, and the light emitted from the first light emitting unit 30 sequentially passes through the second light emitting unit 40 and the third light emitting unit 50, and the light emitted from the second light emitting unit 40 passes through the third light emitting unit 50.

In the present embodiment, the first light emitting unit 30 is bonded to the second light emitting unit 40 through the first bonding layer 61, and the second light emitting unit 40 is bonded to the second light emitting unit 40 through the second bonding layer 81.

Specifically, the first adhesive layer 61 is located between the second semiconductor layer 35 of the first light emitting unit 30 and the first semiconductor layer 41 of the second light emitting unit 40, and the second adhesive layer 81 is located between the second semiconductor layer 45 of the second light emitting unit 40 and the second semiconductor layer 55 of the third light emitting unit 50.

The second semiconductor layer 35 of the first light emitting unit 30 includes a gallium nitride layer 351 and a transition layer 353 stacked in this order, the gallium nitride layer 351 being on the light emitting layer 33, the transition layer 353 being on the gallium nitride layer 351, the transition layer 353 being provided with a conductive layer 51; the second semiconductor layer 45 of the second light emitting unit 40 includes a gallium nitride layer 451 and a transition layer 453 sequentially stacked, the gallium nitride layer 451 is located on the light emitting layer 43, the transition layer 453 is located on the gallium nitride layer 451, the conductive layer 71 is disposed on the transition layer 453, and the first adhesive layer 61 is located between the conductive layer 51 and the first semiconductor layer 41 of the second light emitting unit 40; the second semiconductor layer 55 of the third light emitting unit 50 includes a gallium nitride layer 551 and a transition layer 553 stacked in this order, the gallium nitride layer 551 is on the light emitting layer 53, the transition layer 553 is on the gallium nitride layer 551, the conductive layer 91 is disposed on the transition layer 553, and the second adhesive layer 81 is between the conductive layer 91 and the conductive layer 71.

While the above description of the related embodiments of the present invention has been provided, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (12)

1. A micro display unit, comprising: the LED light-emitting device comprises a first light-emitting unit and a second light-emitting unit which are arranged in opposite directions, wherein each of the first light-emitting unit and the second light-emitting unit comprises a first semiconductor layer, a light-emitting layer and a second semiconductor layer which are sequentially stacked, the light-emitting layer is positioned between the first semiconductor layer and the second semiconductor layer, the first light-emitting unit is bonded with the second light-emitting unit through the first layer, the second semiconductor layer of the first light-emitting unit and/or the second semiconductor layer of the second light-emitting unit comprises a gallium nitride layer and a transition layer which are sequentially stacked, the gallium nitride layer is positioned on the light-emitting layer, the transition layer is positioned on the gallium nitride layer, a conducting layer is arranged on the transition layer, the first bonding layer is positioned on the conducting layer, one side of the conducting layer faces the first bonding layer, and the other side of the conducting layer faces the conducting layer, and the other side of the conducting layer faces the transition layer.

2. The microdisplay unit of claim 1 in which the transition layer is an indium gallium nitride layer.

3. A microdisplay unit according to claim 2, wherein the indium gallium nitride layer has a gradually decreasing indium content from a location near the conductive layer to a location remote from the conductive layer.

4. A microdisplay unit according to claim 3, wherein the indium gallium nitride layer has the same indium content at different locations at the same distance from the conductive layer in the thickness direction.

5. A microdisplay unit according to any of claims 1-4, wherein the indium content of the conductive layer has a highest value point in the thickness direction, said highest value point being located on the front surface of the conductive layer, or said highest value point being located on the back surface of the conductive layer, or said highest value point being located between the front surface of the conductive layer and the back surface of the conductive layer.

6. A microdisplay unit according to claim 5, wherein the conductive layer has the same indium content along the same horizontal position at the highest value point.

7. The microdisplay unit of claim 5 in which the indium content of the conductive layer increases and decreases from the front surface of the conductive layer to the back surface of the conductive layer in the thickness direction.

8. The microdisplay unit of claim 7 in which the conductive layer has the same indium content at different locations at the same distance from the front surface of the conductive layer in the thickness direction.

9. A microdisplay unit according to claim 5, wherein the contact electrode is in point contact with the highest indium content value in the conductive layer.

10. The microdisplay unit of claim 1 in which the conductive layer back and the transition layer back face have the same indium content.

11. The micro display unit as set forth in claim 1, wherein a surface of the conductive layer contacting the first adhesive layer is roughened.

12. A display device having a micro display unit as claimed in any one of claims 1 to 11.