Micro light emitting device and display apparatus including the same

Abstract

The present disclosure relates to a micro light emitting device and a display apparatus including the same. The micro light emitting device includes a first semiconductor layer doped with a first impurity having a first conductivity type; a light emitting layer disposed on an upper surface of the first semiconductor layer; a second semiconductor layer disposed on an upper surface of the light emitting layer and doped with a second impurity having a second conductivity type electrically opposite to the first conductivity type; an insulating layer disposed on an upper surface of the second semiconductor layer; a first electrode disposed on an upper surface of the insulating layer and electrically connected to the first semiconductor layer; a second electrode disposed on the upper surface of the insulating layer and electrically connected to the second semiconductor layer; and an aluminum nitride layer disposed on a lower surface of the first semiconductor layer and having a flat surface.

Description

Technical Field

[0001] This disclosure relates to micro light-emitting devices and display devices including the same, and more particularly, to micro light-emitting devices having structures suitable for alignment in a fluid self-assembly method and display devices including the same. Background Technology

[0002] Light-emitting diodes (LEDs) have seen increased industrial demand due to their low power consumption and environmental friendliness, used in lighting devices, LCD backlighting, and as pixels in display devices. Recently, micro-LED display devices using micro-unit LED chips as pixels have been developed. In manufacturing display devices using micro-unit LED chips, laser stripping or pick-and-place methods are used to transfer the micro-LEDs. However, in this method, productivity decreases as the size of the micro-LEDs decreases and the size of the display device increases. Summary of the Invention

[0003] A micro light-emitting device is provided having a structure suitable for alignment in a fluid self-assembly method.

[0004] A display device is provided that can be manufactured by a fluid self-assembly method.

[0005] Additional aspects will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practicing embodiments of this disclosure.

[0006] According to one aspect of this disclosure, a micro light-emitting device includes: a first semiconductor layer doped with a first impurity having a first conductivity; a light-emitting layer disposed on an upper surface of the first semiconductor layer; a second semiconductor layer disposed on the upper surface of the light-emitting layer, the second semiconductor layer being doped with a second impurity having a second conductivity opposite to the first conductivity; an insulating layer disposed on the upper surface of the second semiconductor layer; a first electrode disposed on the upper surface of the insulating layer and electrically connected to the first semiconductor layer; a second electrode disposed on the upper surface of the insulating layer and electrically connected to the second semiconductor layer; and an aluminum nitride layer disposed on a lower surface of the first semiconductor layer, the aluminum nitride layer including a flat surface.

[0007] The width of a micro light-emitting device can range from about 1 μm to about 100 μm.

[0008] The width of the first semiconductor layer can be greater than the thickness of the micro light-emitting device.

[0009] The thickness of the micro light-emitting device can be in the range of about 2 μm to about 10 μm, and the width of the first semiconductor layer can be in the range of about 5 μm to about 50 μm.

[0010] The width of the second semiconductor layer can be greater than the thickness of the micro light-emitting device.

[0011] The side surface of the micro light-emitting device can be tilted so that the width of the first semiconductor layer is greater than the width of the second semiconductor layer.

[0012] The surface roughness of the aluminum nitride layer can be about 50 nm or less.

[0013] The surface roughness of the aluminum nitride layer can be about 10 nm or less.

[0014] The micro light-emitting device may also include an irregular light-scattering structure distributed inside the first semiconductor layer.

[0015] The aluminum nitride layer may include multiple isolated grooves.

[0016] Each of the plurality of isolated grooves may have a point shape, and the plurality of isolated grooves may be arranged in two dimensions on the surface of the aluminum nitride layer.

[0017] Each of the plurality of isolated grooves may have an annular shape, and the plurality of isolated grooves may be arranged concentrically on the surface of the aluminum nitride layer.

[0018] The second electrode can be arranged at a position corresponding to the center of the second semiconductor layer in the horizontal direction, and the first electrode can be arranged at a position corresponding to the edge of the second semiconductor layer in the horizontal direction.

[0019] The first electrode can have a symmetrical shape around the second electrode.

[0020] The micro light-emitting device may further include a via through the second semiconductor layer and the light-emitting layer, wherein an insulating layer extends to surround the sidewall of the via, a first electrode is configured to contact the first semiconductor layer through the via, and a second electrode may be configured to penetrate the insulating layer and contact the second semiconductor layer.

[0021] The micro light-emitting device may further include a bonding diffusion prevention wall disposed between the first electrode and the second electrode.

[0022] The bonding diffusion prevention wall can have a protruding shape on the upper surface of the insulation layer.

[0023] The joint diffusion prevention wall can have a groove shape.

[0024] Viewed vertically, a micro light-emitting device can have a rectangular cross-section, and the first electrode can be arranged in two vertex regions facing each other in the diagonal direction.

[0025] The micro light-emitting device may further include bonding pads arranged in each of two additional vertex regions different from the two vertex regions, the two additional vertex regions facing each other in a diagonal direction different from the diagonal direction.

[0026] According to one aspect of this disclosure, a display device includes a display substrate and a plurality of micro light-emitting devices disposed on the display substrate, wherein at least one of the plurality of micro light-emitting devices includes: a first semiconductor layer doped with a first impurity having a first conductivity; a light-emitting layer disposed on an upper surface of the first semiconductor layer; a second semiconductor layer disposed on the upper surface of the light-emitting layer, the second semiconductor layer being doped with a second impurity having a second conductivity opposite to the first conductivity; an insulating layer disposed on the upper surface of the second semiconductor layer; a first electrode disposed on the upper surface of the insulating layer and electrically connected to the first semiconductor layer; a second electrode disposed on the upper surface of the insulating layer and electrically connected to the second semiconductor layer; and an aluminum nitride layer disposed on a lower surface of the first semiconductor layer, the aluminum nitride layer including a flat surface.

[0027] The display device may further include a wavelength conversion layer configured to convert the wavelength of light emitted from the plurality of micro light-emitting devices.

[0028] The wavelength conversion layer may include: a first wavelength conversion layer configured to convert the light emitted by the plurality of micro light-emitting devices into light of a first wavelength band; and a second wavelength conversion layer configured to convert the light emitted by the plurality of micro light-emitting devices into light of a second wavelength band different from the first wavelength band.

[0029] The display device may further include a color filter layer comprising: a first filter arranged facing the first wavelength conversion layer and configured to transmit light of a first wavelength band; and a second filter arranged facing the second wavelength conversion layer and configured to transmit light of a second wavelength band.

[0030] According to one aspect of the present invention, a micro light-emitting device includes a first electrode on a first surface of the micro light-emitting device; and an aluminum nitride layer on a second surface of the micro light-emitting device opposite to the first surface, wherein the surface roughness of the aluminum nitride layer is 50 nm or less.

[0031] The first shape of the first electrode can be radially symmetrical about the center of the micro light-emitting device.

[0032] The micro light-emitting device may also include a second electrode on the first surface, wherein the second shape of the second electrode is radially symmetrical about the center of the micro light-emitting device.

[0033] According to one aspect of the present invention, a micro light-emitting device includes: a first semiconductor layer doped with a first impurity having a first conductivity; a light-emitting layer disposed on an upper surface of the first semiconductor layer; a second semiconductor layer disposed on the upper surface of the light-emitting layer, the second semiconductor layer being doped with a second impurity having a second conductivity opposite to the first conductivity; an insulating layer disposed on the upper surface of the second semiconductor layer; a first electrode disposed on the upper surface of the insulating layer and electrically connected to the first semiconductor layer; a second electrode disposed on the upper surface of the insulating layer and electrically connected to the second semiconductor layer; a bonding diffusion prevention wall disposed between the first electrode and the second electrode; bonding pads disposed on the upper surface of the insulating layer; and an aluminum nitride layer disposed on a lower surface of the first semiconductor layer, the aluminum nitride layer including a flat surface. Attached Figure Description

[0034] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 A cross-sectional view is shown schematically illustrating the structure of a micro light-emitting device according to one embodiment;

[0036] Figures 2A to 2C A plan view illustrating various electrode structures of a micro light-emitting device according to an embodiment;

[0037] Figures 3A to 3D To illustrate manufacturing Figure 1 A cross-sectional view of the process of the micro light-emitting device shown;

[0038] Figure 4 A perspective view illustrating an example method of aligning a micro-light-emitting device using a fluid self-assembly method according to one embodiment;

[0039] Figure 5 A scanning process for aligning a micro light-emitting device is schematically illustrated according to one embodiment;

[0040] Figure 6 A cross-sectional view showing a schematic structure of a transfer substrate according to one embodiment, wherein micro-light-emitting devices are arranged in the transfer substrate;

[0041] Figure 7 A cross-sectional view illustrating, according to one embodiment, the process of transferring a micro-light-emitting device aligned on a transfer substrate onto a display substrate.

[0042] Figure 8 A cross-sectional view is shown schematically illustrating the structure of a micro light-emitting device according to one embodiment;

[0043] Figure 9A cross-sectional view is shown schematically illustrating the structure of a micro light-emitting device according to one embodiment;

[0044] Figure 10A and 10B This is a floor plan, showing... Figure 9 An example of multiple grooves formed in the aluminum nitride layer of a micro light-emitting device;

[0045] Figure 11 A cross-sectional view is shown schematically illustrating the structure of a micro light-emitting device according to one embodiment;

[0046] Figure 12 A cross-sectional view illustrating the structure of a display device according to one embodiment;

[0047] Figure 13 A cross-sectional view illustrating the structure of a display device according to one embodiment;

[0048] Figure 14 This is a schematic block diagram of an electronic device according to one embodiment;

[0049] Figure 15 An example of a display device applied to a mobile device according to an embodiment is shown;

[0050] Figure 16 An example of a display device according to an embodiment being applied to a vehicle display device is shown;

[0051] Figure 17 An example of a display device according to an embodiment being applied to augmented reality glasses or virtual reality glasses is shown;

[0052] Figure 18 An example of a display device applied to a sign according to an embodiment is shown; and

[0053] Figure 19 An example of a display device applied to a wearable display according to an embodiment is shown. Detailed Implementation

[0054] The embodiments will now be described in detail, examples of which are shown in the accompanying drawings, wherein the same reference numerals always denote the same elements. In this respect, embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, the embodiments are described below only by reference to the accompanying drawings to explain various aspects. As used herein, the term “and / or” includes any and all combinations of one or more related listed items. When following a column of elements, expressions such as “…at least one of…” modify the entire column of elements, without modifying any individual element within that column.

[0055] The miniature light-emitting device and the display device including the same will be described in detail below with reference to the accompanying drawings. In the following drawings, the same reference numerals denote the same parts, and for clarity and convenience, the dimensions of each part in the drawings may be enlarged. Furthermore, the embodiments described below are merely examples, and various modifications to these embodiments are possible.

[0056] The term "upper" or "above" as used below may include not only the directly above in contact but also the non-contacting above. Unless otherwise stated, singular terms may include plural forms. Furthermore, when a part "includes" a component, unless otherwise stated, it means that other components may be included, rather than excluded.

[0057] The use of the term "the" and similar descriptive terms may correspond to both the singular and plural. If there are no explicit or contradictory statements regarding the order of the steps constituting the method, these steps may be performed in an appropriate order and are not necessarily limited to the order described.

[0058] In addition, terms described in the specification, such as “unit” and “module”, refer to a unit that performs at least one function or operation, which may be implemented as hardware or software, or as a combination of hardware and software.

[0059] The lines connecting the components shown in the figure are illustrations of functional connections and / or physical or electrical connections, and may represent various functional connections, physical connections or electrical connections that can be replaced or added in an actual device.

[0060] All examples or illustrative terms are used only to describe the technical ideas in detail, and the scope is not limited by these examples or illustrative terms, except as limited by the claims.

[0061] Figure 1 A cross-sectional view showing the structure of a micro light-emitting device according to one embodiment. (Refer to...) Figure 1The micro-light-emitting device 100 may include a first semiconductor layer 103, a light-emitting layer 104 disposed on the upper surface of the first semiconductor layer 103, a second semiconductor layer 105 disposed on the upper surface of the light-emitting layer 104, an insulating layer 106 disposed on the upper surface of the second semiconductor layer 105, a first electrode 108 disposed on the upper surface of the insulating layer 106 such that the first electrode 108 is electrically connected to the first semiconductor layer 103, a second electrode 107 disposed on the upper surface of the insulating layer 106 such that the second electrode 107 is electrically connected to the second semiconductor layer 105, and an aluminum nitride (AlN) layer 102 disposed on the lower surface of the first semiconductor layer 103 and having a flat surface. The first electrode 108 and the second electrode 107 may be disposed on the upper surface (e.g., the first surface) of the micro-light-emitting device 100. The AlN layer 102 may be disposed on the lower surface (e.g., the second surface) of the micro-light-emitting device 100.

[0062] The first semiconductor layer 103 and the second semiconductor layer 105 may comprise, for example, group III-V or group II-VI compound semiconductors. The first semiconductor layer 103 and the second semiconductor layer 105 may provide electrons and holes to the light-emitting layer 104. For this purpose, the first semiconductor layer 103 and the second semiconductor layer 105 may be electrically doped with opposite types. For example, the first semiconductor layer 103 may be doped with an n-type impurity (e.g., a first impurity having a first conductivity), and the second semiconductor layer 105 may be doped with a p-type impurity (e.g., a second impurity having a second conductivity), or the first semiconductor layer 103 may be doped as p-type and the second semiconductor layer 105 may be doped as n-type.

[0063] The light-emitting layer 104 has a quantum well structure, wherein quantum wells are arranged between potential barriers. Light can be generated when electrons and holes supplied from the first semiconductor layer 103 and the second semiconductor layer 105 recombine in the quantum wells of the light-emitting layer 104. The wavelength of the light generated from the light-emitting layer 104 can be determined based on the band gap of the material forming the quantum wells in the light-emitting layer 104. The light-emitting layer 104 may have only one quantum well, or it may have a multiple quantum well (MQW) structure, wherein multiple quantum wells are alternately arranged with multiple potential barriers. The thickness of the light-emitting layer 104 or the number of quantum wells in the light-emitting layer 104 can be appropriately selected considering the driving voltage and luminous efficiency of the light-emitting device.

[0064] To facilitate alignment of the micro-light-emitting device 100 in the fluid self-assembly method described below, both the first electrode 108 and the second electrode 107 can be disposed on one surface of the micro-light-emitting device 100. For example, refer to... Figure 1An insulating layer 106 may be formed on the upper surface of the second semiconductor layer 105, and both the first electrode 108 and the second electrode 107 may be disposed on the upper surface of the insulating layer 106. To electrically connect the first electrode 108 to the first semiconductor layer 103, the micro-light-emitting device 100 may further include a via V passing through the second semiconductor layer 105 and the light-emitting layer 104. The insulating layer 106 may extend to surround the sidewalls of the via V. In other words, the portion of the second semiconductor layer 105 exposed by the via V and the portion of the light-emitting layer 104 exposed by the via V may be covered by the insulating layer 106. The first electrode 108 extends from the upper surface of the insulating layer 106 to the upper surface of the first semiconductor layer 103 exposed by the via V to contact the first semiconductor layer 103 through the via V. The second electrode 107 may be configured to penetrate the insulating layer 106 and contact the second semiconductor layer 105. Furthermore, a portion of the second electrode 107 may extend laterally further from the upper surface of the insulating layer 106.

[0065] The AlN layer 102 can provide a flat lower surface to facilitate the alignment of the micro-light-emitting device 100 in a fluid self-assembly method. For this purpose, the AlN layer 102 can have a very smooth and flat lower surface. For example, the root mean square (RMS) of the surface roughness of the lower surface of the AlN layer 102 can be about 50 nm or less, or about 10 nm or less.

[0066] Furthermore, to facilitate alignment of the micro-light-emitting device 100 in the fluid self-assembly method, the micro-light-emitting device 100 may have a shape in which the diameter or width of the micro-light-emitting device 100 is greater than the thickness of the micro-light-emitting device 100. Specifically, the diameter or width W1 of the first semiconductor layer 103 may be greater than the thickness T of the micro-light-emitting device 100. For example, the thickness T of the micro-light-emitting device 100 may be less than about 20 μm, for example, in the range of about 1 μm to about 20 μm, or in the range of about 2 μm to about 10 μm, and the diameter or width W1 of the first semiconductor layer 103 may be less than about 100 μm, for example, in the range of about 1 μm to about 100 μm, or in the range of about 5 μm to about 50 μm. For example, the diameter or width W1 of the first semiconductor layer 103 may be greater than the thickness T, or greater than two or five times the thickness T of the micro-light-emitting device 100. Here, the size of the micro-light-emitting device 100, i.e., its diameter or width, may be defined as the diameter or width W1 of the widest portion of the first semiconductor layer 103. Therefore, the size, i.e., the diameter or width, of the micro light-emitting device 100 can be, for example, in the range of about 1 μm to about 100 μm, or in the range of about 5 μm to about 50 μm.

[0067] According to one embodiment, the micro-light-emitting device 100 may have a sloping side surface, such that the diameter or width W1 of both the AlN layer 102 and the first semiconductor layer 103 is greater than the diameter or width W2 of the second semiconductor layer 105 and the insulating layer 106. For example, the diameter or width W2 of the second semiconductor layer 105 may be 0.7 times or greater than the diameter or width W1 of the first semiconductor layer 103 and less than the diameter or width W1, or it may be 0.8 times or greater than the diameter or width W1 and 0.95 times or less than the diameter or width W1. Therefore, the area of ​​the AlN layer 102 and the first semiconductor layer 103 may be greater than the area of ​​the second semiconductor layer 105 and the insulating layer 106. Furthermore, the diameter or width W2 of the second semiconductor layer 105 of the micro-light-emitting device 100 may also be greater than the thickness T of the micro-light-emitting device 100.

[0068] Furthermore, the micro-light-emitting device 100 may also include a bonding diffusion prevention wall 109 disposed between the first electrode 108 and the second electrode 107 on the upper surface of the insulating layer 106. For example, during the manufacturing process of a display device, when the first electrode 108 and the second electrode 107 of the micro-light-emitting device 100 are bonded to corresponding electrode pads on the display substrate of the display device, the bonding diffusion prevention wall 109 prevents bonding materials such as solder bumps from diffusing between the first electrode 108 and the second electrode 107 to prevent short circuits. The bonding diffusion prevention wall 109 may have a shape that protrudes above the upper surface of the insulating layer 106. The thickness of the bonding diffusion prevention wall 109 may be less than or equal to the thickness of the first electrode 108 and the second electrode 107. Furthermore, the bonding diffusion prevention wall 109 may be made of an electrically insulating material.

[0069] In the process of manufacturing the display device, in order to easily bond the first electrode 108 and the second electrode 107 of the micro light-emitting device 100 to the corresponding electrode pads on the display substrate, the first electrode 108 and the second electrode 107 may have symmetrical shapes. In other words, for example, the first electrode 108 and the second electrode 107 may have a first shape and a second shape, each of which is radially symmetrical with respect to the center of the micro light-emitting device 100. Figures 2A to 2C This is a plan view showing the various electrode structures of the micro light-emitting device 100.

[0070] Reference Figure 2AThe horizontal cross-section (e.g., the cross-section when viewed vertically) of the micro-light-emitting device 100 may have a circular shape. The second electrode 107 may be disposed at the center of the second semiconductor layer 105, i.e., at a position corresponding to the center of the micro-light-emitting device 100 in the horizontal direction (e.g., the width direction). The second electrode 107 may have a circular shape. However, this disclosure is not necessarily limited to this; the second electrode 107 may have a quadrilateral or other polygonal shape. The first electrode 108 may be disposed at the edge of the micro-light-emitting device 100, i.e., at a position corresponding to the edge of the second semiconductor layer 105 in the horizontal direction. The first electrode 108 may have a symmetrical shape surrounding the second electrode 107. For example, the first electrode 108 may have the form of two separate semicircular rings surrounding the second electrode 107. Figure 2A In the illustration, the first electrode 108 is shown as having the shape of two separate rings, but this disclosure is not limited thereto. The first electrode 108 may have, for example, the shape of three or more separate rings. Even though the first electrode 108 has separate portions, they can still be electrically connected to each other when they are bonded to electrode pads on the display substrate.

[0071] Furthermore, the bonding diffusion prevention wall 109 can be arranged in a ring shape between the first electrode 108 and the second electrode 107. The bonding diffusion prevention wall 109 can have the shape of two or more separate rings like the first electrode 108, and can be arranged to completely block the path between the first electrode 108 and the second electrode 107.

[0072] Reference Figure 2B Each of the first electrode 108 and the bonding diffusion prevention wall 109 may have the form of a complete ring.

[0073] Reference Figure 2C The micro-light-emitting device 100 may have a rectangular cross-section. A second electrode 107 is disposed at the center of the micro-light-emitting device 100 and may have a circular or polygonal shape. First electrodes 108 may be disposed at two opposite vertices of the rectangular shape along their diagonal directions. Furthermore, the micro-light-emitting device 100 may include bonding pads 110 disposed at two different opposite vertices along different diagonal directions. In other words, bonding pads 110 may be disposed at two other opposite vertices of the rectangular shape along another diagonal direction. The bonding pads 110 are disposed on the upper surface of the insulating layer 106. When the first electrode 108 and the second electrode 107 of the micro-light-emitting device 100 are bonded to the electrode pads on the display substrate, the bonding pads 110 bond to the display substrate, allowing the micro-light-emitting device 100 to be stably mounted on the display substrate. Alternatively, the first electrode 108 may be disposed at all four vertices without bonding pads 110.

[0074] Figures 3A to 3D To illustrate manufacturing Figure 1 A cross-sectional view of the process of the micro light-emitting device 100 shown.

[0075] Reference Figure 3A An AlN layer 102, a first semiconductor layer 103, a light-emitting layer 104, and a second semiconductor layer 105 can be sequentially grown on a growth substrate 101. The growth substrate 101 can be, for example, a silicon substrate. The AlN layer 102 can be used as a buffer layer for growing compound semiconductors on a silicon substrate.

[0076] Reference Figure 3B The first semiconductor layer 103 can be exposed by partially etching the second semiconductor layer 105, the light-emitting layer 104, and the first semiconductor layer 103 to a portion of the first semiconductor layer 103 to form a via V.

[0077] Reference Figure 3C An insulating layer 106 can be formed on the second semiconductor layer 105. The insulating layer 106 extends to the inner sidewall of the via V, such that the portion of the second semiconductor layer 105 exposed by the via V and the portion of the light-emitting layer 104 exposed by the via V can be covered by the insulating layer 106. Then, the first electrode 108 and the second electrode 107 can be formed to contact the first semiconductor layer 103 and the second semiconductor layer 105, respectively, and a bonding diffusion prevention wall 109 can be formed between the first electrode 108 and the second electrode 107.

[0078] Reference Figure 3D The insulating layer 106, the second semiconductor layer 105, the light-emitting layer 104, the first semiconductor layer 103, and the AlN layer 102 are partially etched to form a plurality of micro-light-emitting devices 100. Although for convenience, in Figure 3D The diagram shows a micro light-emitting device 100, but a large number of micro light-emitting devices 100 can be formed on a growth substrate 101.

[0079] Subsequently, the micro-light-emitting device 100 can be separated from the growth substrate 101 by chemical peeling. When the micro-light-emitting device 100 is separated by chemical peeling, the lower surface of the micro-light-emitting device 100, that is, the lower surface of the AlN layer 102, can be very smooth.

[0080] Before being mounted onto the display substrate of a display device, the micro-light-emitting device 100 formed in this way can first be aligned on a separate transfer substrate using a fluid self-assembly method. Figure 4 This is a perspective view illustrating an example method of aligning a micro-light-emitting device 100 using a fluid self-assembly method.

[0081] Reference Figure 4Multiple micro-light-emitting devices 100 can be supplied on the upper surface of a transfer substrate 130 having grooves 135 arranged in two dimensions. After liquid is supplied to the grooves 135 of the transfer substrate 130, the multiple micro-light-emitting devices 100 can be directly sprayed onto the transfer substrate 130, or supplied onto the transfer substrate 130 in a state included in a suspension.

[0082] The liquid supplied to the recess 135 can be any type of liquid, as long as it does not corrode or damage the micro-light-emitting device 100, and can be supplied to the recess 135 by various methods (such as jetting, dispensing, inkjet dotting, methods for allowing the liquid to flow onto the transfer substrate 130, etc.). The liquid can include, for example, any one or more of water, ethanol, alcohol, polyols, ketones, halogenated hydrocarbons, acetone, flux, and organic solvents. Organic solvents can include, for example, isopropanol (IPA). The amount of liquid supplied can be varied to fit the recess 135 or overflow from the recess 135.

[0083] Multiple micro-light-emitting devices 100 can be directly sprayed onto the transfer substrate 130 without another liquid, or they can be supplied onto the transfer substrate 130 in a state contained in a suspension. As a method of supplying the micro-light-emitting devices 100 contained in the suspension, various methods can be used, such as spraying methods, dispensing methods for dripping liquid, inkjet dot methods for discharging liquid (e.g., printing methods), and methods for causing the suspension to flow onto the transfer substrate 130.

[0084] Figure 5 The scanning process for aligning the micro-light-emitting device 100 is illustrated schematically. (Refer to...) Figure 5 The absorber 10 can scan the transfer substrate 130. As it scans through multiple grooves 135 and contacts the transfer substrate 130, the absorber 10 can move the micro-light-emitting device 100 into the grooves 135 and can also absorb the liquid L in the grooves 135. The absorber 10 is sufficient as long as it is made of a material capable of absorbing the liquid L, and its shape or structure is not limited. The absorber 10 can include, for example, fabric, tissue paper, polyester fiber, paper, or a wiping material.

[0085] The absorber 10 can be used independently without other auxiliary devices, but is not limited thereto, and can be connected to the support 20 to facilitate scanning the transfer substrate 130. The support 20 can have various shapes and structures suitable for scanning the transfer substrate 130. For example, the support 20 can be in the form of a rod, blade, plate, wipe, etc. The absorber 10 can be provided on either side of the support 20 or surrounding the support 20. The shapes of the support 20 and the absorber 10 are not limited to the rectangular cross-sectional shape shown, and can have circular or other cross-sectional shapes.

[0086] The absorber 10 can be scanned while pressing the transfer substrate 130 with appropriate pressure. Because the partition walls 131 of the transfer substrate 130 are made of a flexible polymer material, the original thickness of the partition walls 131 can be restored after scanning even if pressure is applied to the transfer substrate 130. Scanning can be performed in various ways, such as sliding, rotating, translating, reciprocating, rolling, spinning, and / or rubbing methods of the absorber 10, and can include both regular and irregular methods. Scanning can be performed by moving the transfer substrate 130 instead of moving the absorber 10, and scanning of the transfer substrate 130 can also be performed using methods such as sliding, rotating, reciprocating translation, rolling, spinning, and / or rubbing. Furthermore, scanning can be performed through the cooperation of the absorber 10 and the transfer substrate 130.

[0087] The operations of supplying liquid L to the grooves 135 of the transfer substrate 130 and supplying micro-light-emitting devices 100 to the transfer substrate 130 can be performed in the reverse order described above. Furthermore, the operations of supplying liquid L to the grooves 135 of the transfer substrate 130 and supplying micro-light-emitting devices 100 to the transfer substrate 130 can be performed simultaneously in one operation. For example, by supplying a suspension including micro-light-emitting devices 100 to the transfer substrate 130, liquid L and micro-light-emitting devices 100 can be supplied to the transfer substrate 130 simultaneously. After the absorber 10 scans the transfer substrate 130, micro-light-emitting devices 100 remaining in the transfer substrate 130 but not entering the grooves 135 can be removed. The above process can be repeated until the micro-light-emitting devices 100 are located in all the grooves 135. As described above, a large number of micro-light-emitting devices 100 can be aligned on a large-area transfer substrate 130 using a fluid self-assembly method.

[0088] Figure 6 A cross-sectional view showing a schematic structure of a transfer substrate 130 according to one embodiment, in which micro-light-emitting devices 100 are arranged. (Refer to...) Figure 6The transfer substrate 130 may include a partition wall 131 disposed on its upper surface and having a plurality of grooves 135. The partition wall 131 may be made of a flexible polymer material. For example, the partition wall 131 may include at least one of an acrylic polymer, a silicone-based polymer, and an epoxy-based polymer. Furthermore, the partition wall 131 may further include a photosensitive material. When the partition wall 131 includes a photosensitive material, the plurality of grooves 135 can be formed by photolithography. When the partition wall 131 does not include a photosensitive material, the plurality of grooves 135 can be formed by etching and molding. The thickness (e.g., height) of the partition wall 131 may be slightly greater than or slightly less than the thickness of the micro-light-emitting device 100. For example, the thickness of the partition wall 131 may be 0.8 to 1.2 times the thickness of the micro-light-emitting device 100.

[0089] Using the fluid self-assembly method described above, a micro-light-emitting device 100 can be arranged in each groove 135. In this case, a partition wall 131 can surround the micro-light-emitting device 100. The micro-light-emitting device 100 can be configured such that the first electrode 108 and the second electrode 107 face upwards, that is, outside the groove 135, and the AlN layer 102 contacts the bottom surface 132 of the groove 135. For this purpose, the bottom surface 132 of the groove 135 that contacts the lower surface of the micro-light-emitting device 100 can be made of a dielectric material with high hydrophilicity and can be a very smooth surface. For example, the RMS surface roughness of the bottom surface 132 of the groove 135 can be about 50 nm or less, or about 10 nm or less. Furthermore, the AlN layer 102 that contacts the bottom surface 132 of the groove 135 can also be hydrophilic and have an RMS surface roughness of about 50 nm or less, or about 10 nm or less.

[0090] Therefore, when the AlN layer 102 contacts the bottom surface 132 of the groove 135 during the fluid self-assembly process, the micro-light-emitting device 100 is positioned within the groove 135 without leaving it due to its high surface energy. Furthermore, since the structure of the micro-light-emitting device 100 has a diameter or width larger than its thickness, the contact area is relatively large when the AlN layer 102 contacts the bottom surface 132 of the groove 135, further increasing the surface energy. Moreover, in the structure of the micro-light-emitting device 100 with inclined side surfaces, because the area of ​​the AlN layer 102 is larger than the area of ​​the insulating layer 106, the surface energy can be further increased when the AlN layer 102 contacts the bottom surface 132 of the groove 135.

[0091] On the other hand, when the first electrode 107 and the second electrode 108 contact the bottom surface 132 of the groove 135 within the groove 135, the micro-light-emitting device 100 can easily detach from the groove 135 even with a relatively weak force due to its low surface energy. Therefore, when aligning the micro-light-emitting device 100 using a fluid self-assembly method, the first electrode 107 and the second electrode 108 can face outwards from the groove 135 when the micro-light-emitting device 100 is fixed in the groove 135. Furthermore, during cleaning operations, the first electrode 107 and the second electrode 108 allow the micro-light-emitting device 100, which is not fixed in the groove 135 and remains on the partition wall 131, to be easily separated from the transfer substrate 130. In this respect, the disclosed micro-light-emitting device 100 can have a structure suitable for alignment in a fluid self-assembly method. Although not shown in the figures, an embossed pattern can be further formed on the upper surface of the partition wall 131, making it easier for the micro-light-emitting device 100 to separate from the partition wall 131.

[0092] Multiple micro-light-emitting devices 100 aligned on the transfer substrate 130 can be transferred to the display substrate of the display device for manufacturing the display device. Figure 7 This is a cross-sectional view schematically illustrating the process of transferring a micro-light-emitting device 100 aligned on a transfer substrate 130 onto a display substrate.

[0093] Reference Figure 7 The display substrate 210 may include a plurality of first electrode pads 211 and a plurality of second electrode pads 212. The display substrate 210 may also include a driving circuit comprising a plurality of thin-film transistors for independently controlling a plurality of micro-light-emitting devices 100. For example, the plurality of thin-film transistors are arranged below the first electrode pads 211 and the second electrode pads 212 in the display substrate 210, and the plurality of thin-film transistors can be electrically connected to the first electrode pads 211 and the second electrode pads 212 via wiring.

[0094] The transfer substrate 130 can be arranged such that the first electrode 108 and the second electrode 107 of the micro-light-emitting device 100 face the display substrate 210. The transfer substrate 130 can then be pressed onto the display substrate 210 such that the first electrode 108 of the micro-light-emitting device 100 contacts the first electrode pad 211 of the display substrate 210, and the second electrode 107 contacts the second electrode pad 212 of the display substrate 210. Then, the first electrode 108 can be bonded to the first electrode pad 211 and the second electrode 107 can be bonded to the second electrode pad 212 using a bonding material such as solder bumps. In this way, the transfer substrate 130 can be detached from the micro-light-emitting device 100 when the micro-light-emitting device 100 is completely fixed to the display substrate 210. As described above, by using the micro-light-emitting device 100 having a structure suitable for alignment in a fluid self-assembly method, a large-area display device can be manufactured relatively easily by a fluid self-assembly method.

[0095] Figure 8 A cross-sectional view is shown schematically illustrating the structure of a micro light-emitting device according to one embodiment. Figure 1 In this context, the bonding diffusion prevention wall 109 has been described as having a protruding structure over the insulating layer 106, but this disclosure is not limited thereto. (See also...) Figure 8 The micro-light-emitting device 100a may include a bonding diffusion prevention wall 109a with an etched structure (e.g., a groove). For example, when forming a via V, a trench can be formed by etching a portion of the second semiconductor layer 105, a portion of the light-emitting layer 104, and / or a portion of the first semiconductor layer 103 at the location of the bonding diffusion prevention wall 109a. An insulating layer 106 can then be formed to cover the sidewalls and bottom surface of the trench with a predetermined thickness. Extensive diffusion of the bonding material between the first electrode 108 and the second electrode 107 can then be prevented because the bonding material flows along the etched groove of the bonding diffusion prevention wall 109a. (No reference provided) Figure 8 Other structures of the described micro light-emitting device 100a can be compared with... Figure 1 The same as those of the micro light-emitting devices 100 shown.

[0096] Figure 9 A cross-sectional view is shown schematically illustrating the structure of a micro light-emitting device according to one embodiment. (Refer to...) Figure 9 The micro-light-emitting device 100b may further include a plurality of grooves 111 formed in the lower surface of the AlN layer 102. The plurality of grooves 111 may be formed by etching the AlN layer 102. The plurality of grooves 111 may be formed by etching into a portion of the first semiconductor layer 103. The plurality of grooves 111 may have a closed structure that isolates them from each other.

[0097] Figure 10A and Figure 10BThis is a floor plan, showing... Figure 9 An example of multiple grooves 111 formed in the AlN layer 102 of the micro-light-emitting device 100b shown. (Refer to...) Figure 10A Multiple grooves 111 can have a point shape and can be arranged two-dimensionally in the lower surface of the AlN layer 102. Furthermore, referring to... Figure 10B Multiple grooves 111 can have an annular shape and can be arranged in a concentric circle shape in the lower surface of AlN layer 102.

[0098] When by reference Figure 4 and Figure 5 When the described fluid self-assembly method aligns the micro-light-emitting device 100b onto the transfer substrate 130, a plurality of grooves 111 can be filled with a liquid for fluid self-assembly. When the AlN layer 102 contacts the bottom surface 132 of the grooves 135 of the transfer substrate 130, the liquid filling the plurality of grooves 111 can further increase the surface energy. Therefore, the micro-light-emitting device 100b can be more stably positioned in the grooves 135 of the transfer substrate 130. For this purpose, the plurality of grooves 111 can have an isolated, closed structure so that the liquid filling the plurality of grooves 111 does not leak. For example, the plurality of grooves 111 can be arranged in the lower surface of the AlN layer 102 so that the liquid does not leak to the edge of the lower surface of the AlN layer 102.

[0099] Furthermore, the multiple grooves 111 can serve as a light scattering structure, which facilitates the emission of light generated from the light-emitting layer 104 of the micro-light-emitting device 100b through the AlN layer 102 to the outside. The light generated from the light-emitting layer 104 can be emitted relatively uniformly to the outside of the AlN layer 102, while being refracted in the multiple grooves 111. For this purpose, the multiple grooves 111 can be arranged irregularly.

[0100] Figure 11 A cross-sectional view is shown schematically illustrating the structure of a micro light-emitting device according to one embodiment. (Refer to...) Figure 11 The micro-light-emitting device 100c may further include light-scattering structures 112 distributed within the first semiconductor layer 103. The light-scattering structures 112 may be made of air, voids, a transparent dielectric material, or a semiconductor material different from the semiconductor material of the first semiconductor layer 103. The width, thickness, shape, or distance between the light-scattering structures 112 may be irregularly distributed. Therefore, light generated from the light-emitting layer 104 can be emitted relatively uniformly to the outside through the irregular light-scattering structures 112 in the first semiconductor layer 103.

[0101] Figure 12 This is a schematic cross-sectional view illustrating the structure of a display device according to an example embodiment. (Refer to...) Figure 12The display device 200 may include a display substrate 210, a plurality of micro light-emitting devices 100 mounted on the display substrate 210, and a wavelength conversion layer 220 disposed on the plurality of micro light-emitting devices 100. In addition, the display device 200 may further include an upper substrate 230 disposed on the wavelength conversion layer 220. Figure 12 It shows the use of Figure 1 The micro light-emitting device 100 shown is used, but micro light-emitting devices 100a, 100b and 100c according to other embodiments may also be used.

[0102] The wavelength conversion layer 220 may include: a first wavelength conversion layer 220R for converting light emitted from the micro-light-emitting device 100 into light of a first wavelength band; a second wavelength conversion layer 220G for converting light emitted from the micro-light-emitting device 100 into light of a second wavelength band different from the first wavelength band; and a third wavelength conversion layer 220B for converting light emitted from the micro-light-emitting device 100 into light of a third wavelength band different from the first and second wavelength bands. For example, the light of the first wavelength band may be red light, the light of the second wavelength band may be green light, and the light of the third wavelength band may be blue light. The first wavelength conversion layer 220R, the second wavelength conversion layer 220G, and the third wavelength conversion layer 220B are arranged spaced apart, with a diaphragm 221 disposed between them, and may be arranged to face the respective micro-light-emitting device 100.

[0103] When the micro-light-emitting device 100 emits blue light, the third wavelength conversion layer 220B may include a resin that transmits blue light. The second wavelength conversion layer 220G can convert the blue light emitted from the micro-light-emitting device 100 to emit green light. The second wavelength conversion layer 220G may include quantum dots or phosphors that are excited by blue light to emit green light. The first wavelength conversion layer 220R can convert the blue light emitted from the micro-light-emitting device 100 into red light for emission. The first wavelength conversion layer 220R may include quantum dots or phosphors that are excited by blue light to emit red light.

[0104] The quantum dots included in the first wavelength conversion layer 220R or the second wavelength conversion layer 220G may have a core-shell structure comprising a core and a shell portion, or may have a shell-less particulate structure. The core-shell structure may be a single-shell or multi-shell structure, such as a double-shell structure. The quantum dots may include group II-VI semiconductors, group III-V semiconductors, group IV-VI semiconductors, group IV semiconductors, and / or graphene quantum dots. The quantum dots may include, for example, Cd, Se, Zn, S, and / or InP, and each quantum dot may have a diameter of tens of nm or smaller, for example, about 10 nm or smaller. The quantum dots included in the first wavelength conversion layer 220R and the second wavelength conversion layer 220G may have different sizes.

[0105] Figure 13 A cross-sectional view schematically illustrating the structure of a display device according to one embodiment. (Refer to...) Figure 13 The display device 300 may further include a cover layer 250 disposed on the wavelength conversion layer 220 and a color filter layer 240 disposed on the cover layer 250. The cover layer 250 and the color filter layer 240 may be disposed on... Figure 12 The display device 200 shown is located between the wavelength conversion layer 220 and the upper substrate 230. The color filter layer 240 includes a first filter 240R, a second filter 240G, and a third filter 240B, separated by a black matrix 241. The first filter 240R, the second filter 240G, and the third filter 240B are arranged facing the first wavelength conversion layer 220R, the second wavelength conversion layer 220G, and the third wavelength conversion layer 220B, respectively. The first filter 240R, the second filter 240G, and the third filter 240B transmit red light, green light, and blue light, respectively, and absorb light of different colors. When the color filter layer 240 is provided, the first filter 240R and the second filter 240G can respectively remove light emitted in the first wavelength conversion layer 220R without wavelength conversion (e.g., light other than red light) or light emitted in the second wavelength conversion layer 220G without wavelength conversion (e.g., light other than green light), thereby improving the color purity of the display device 300.

[0106] The aforementioned display device can be applied to various electronic devices with screen display functions. Figure 14 This is a schematic block diagram of an electronic device according to an example embodiment. (Refer to...) Figure 14Electronic device 8201 can be provided in a network environment 8200. In the network environment 8200, electronic device 8201 can communicate with another electronic device 8202 through a first network 8298 (such as a short-range wireless communication network), or can communicate with another electronic device 8204 and / or server 8208 through a second network 8299 (such as a long-range wireless communication network). Electronic device 8201 can communicate with electronic device 8204 through server 8208. Electronic device 8201 may include a processor 8220, a memory 8230, an input device 8250, an audio output device 8255, a display device 8260, an audio module 8270, a sensor module 8210, and an interface 8277, a haptic module 8279, a camera module 8280, a power management module 8288, a battery 8289, a communication module 8290, a user identification module 8296, and / or an antenna module 8297. In electronic device 8201, some of these components may be omitted or other components may be added. Some of these components can be implemented as an integrated circuit. For example, sensor module 8210 (fingerprint sensor 8211, accelerometer 8212, position sensor 8213, 3D sensor 8214, iris sensor, illuminance sensor, etc.) can be implemented by embedding it in display device 8260 (display, etc.).

[0107] Processor 8220 can execute software (program 8240, etc.) to control one or more other components (such as hardware, software components, etc.) connected to electronic device 8201 and perform various data processing or operations. As part of the data processing or operation, processor 8220 can load commands and / or data received from other components (sensor module 8210, communication module 8290, etc.) into volatile memory 8232, process the commands and / or data stored in volatile memory 8232, and store the result data in non-volatile memory 8234. Non-volatile memory 8234 may include internal memory 8236 and removable external memory 8238 installed in electronic device 8201. Processor 8220 may include a main processor 8221 (such as a central processing unit, application processor, etc.) and an auxiliary processor 8223 (such as a graphics processing unit, image signal processor, sensor hub processor, communication processor, etc.), which may operate independently or together with main processor 8221. The auxiliary processor 8223 can use less power than the main processor 8221 and can perform specialized functions.

[0108] The auxiliary processor 8223 can control functions and / or states related to some components of other electronic devices 8201 (such as display device 8260, sensor module 8210, communication module 8290, etc.) on behalf of the main processor 8221 when the main processor 8221 is in an inactive state (sleep state), or it can work with the main processor 8221 to control functions and / or states related to some components of other electronic devices 8201 (such as display device 8260, sensor module 8210, communication module 8290, etc.) when the main processor 8221 is in an active state (application execution state). The auxiliary processor 8223 (such as an image signal processor, communication processor, etc.) can be implemented as part of other functionally related components (such as camera module 8280, communication module 8290, etc.).

[0109] The memory 8230 may store various data required by components of the electronic device 8201 (such as processor 8220, sensor module 8210, etc.). This data may include, for example, software (such as program 8240), input data for associated commands, and / or output data. The memory 8230 may include volatile memory 8232 and / or non-volatile memory 8234.

[0110] The program 8240 can be stored as software in the memory 8230 and may include an operating system 8242, middleware 8244 and / or application 8246.

[0111] Input device 8250 can receive commands and / or data from outside the electronic device 8201 (the user) for use by components of the electronic device 8201 (such as processor 8220). Input device 8250 may include a remote control, microphone, mouse, keyboard, and / or digital pen (such as a stylus).

[0112] Audio output device 8255 can output audio signals to the outside of electronic device 8201. Audio output device 8255 may include a speaker and / or a receiver. The speaker can be used for general purposes such as multimedia playback or recording playback, and the receiver can be used to answer incoming calls. The receiver can be integrated as part of the speaker or can be implemented as a separate, independent device.

[0113] Display device 8260 can visually provide information to the outside of electronic device 8201. Display device 8260 may include a display, holographic device, or projector, as well as control circuitry for controlling the device. Display device 8260 may include the aforementioned driving circuitry, micro-light-emitting devices, side-reflective structures, bottom-reflective structures, etc. Display device 8260 may include touch circuitry configured to sense touch and / or sensor circuitry configured to measure the intensity of the force generated by touch (such as a pressure sensor).

[0114] Audio module 8270 can convert sound into electrical signals, or conversely, can convert electrical signals into sound. Audio module 8270 can acquire sound through input device 8250, or output sound through the speaker and / or headphones of audio output device 8255, and / or other electronic devices (such as other electronic devices 8202) directly or wirelessly connected to electronic device 8201.

[0115] Sensor module 8210 can detect the operating status (such as power, temperature, etc.) or external environmental status (such as user status) of electronic device 8201, and can generate electrical signals and / or data values ​​corresponding to the detected status. Sensor module 8210 may include gesture sensors, gyroscope sensors, barometric pressure sensors, magnetic sensors, accelerometers, grip sensors, proximity sensors, color sensors, infrared (IR) sensors, biometric sensors, temperature sensors, humidity sensors, and / or illuminance sensors.

[0116] Interface 8277 may support one or more specified protocols, which can be used to connect electronic device 8201 directly or wirelessly to another electronic device (such as other electronic device 8202). Interface 8277 may include a High Definition Multimedia Interface (HDMI), a Universal Serial Bus (USB) interface, an SD card interface, and / or an audio interface.

[0117] Connection terminal 8278 may include a connector through which electronic device 8201 can be physically connected to another electronic device (such as other electronic device 8202). Connection terminal 8278 may include an HDMI connector, a USB connector, an SD card connector, and / or an audio connector (such as a headphone connector).

[0118] The haptic module 8279 can convert electrical signals into mechanical stimuli (such as vibration, movement, etc.) or electrical stimuli that can be perceived by the user through touch or kinesthesia. The haptic module 8279 may include a motor, a piezoelectric element, and / or an electrical stimulation device.

[0119] Camera module 8280 can capture still images and video. Camera module 8280 may include a lens assembly (which includes one or more lenses), an image sensor, an image signal processor, and / or a flash. The lens assembly included in camera module 8280 can collect light emitted from an object (which is the target of image capture).

[0120] The power management module 8288 manages the power supplied to the electronic device 8201. The power management module 8288 can be implemented as part of a power management integrated circuit (PMIC).

[0121] Battery 8289 can supply power to components of electronic device 8201. Battery 8289 may include non-rechargeable primary batteries, rechargeable secondary batteries, and / or fuel cells.

[0122] Communication module 8290 can support the establishment of direct (wired) communication channels and / or wireless communication channels, and communicate between electronic device 8201 and other electronic devices (such as other electronic devices 8202, other electronic devices 8204, server 8208, etc.) through the established communication channels. Communication module 8290 may include one or more communication processors that operate independently of processor 8220 (such as an application processor) and support direct and / or wireless communication. Communication module 8290 may include wireless communication module 8292 (such as a cellular communication module, a short-range wireless communication module, a Global Navigation Satellite System (GNSS) communication module, etc.) and / or wired communication module 8294 (such as a local area network (LAN) communication module, a power line communication module, etc.). Among these communication modules, the corresponding communication module can communicate with other electronic devices through a first network 8298 (such as a short-range communication network of Bluetooth, WiFi Direct, or Infrared Data Association (IrDA)) or a second network 8299 (a cellular network, the Internet, or a telecommunications network such as a computer network (such as a LAN, WAN, etc.). These various types of communication modules can be integrated into a single component (such as a single chip) or implemented as multiple separate components (multiple chips). The wireless communication module 8292 can use user information (such as the International Mobile Subscriber Identity (IMSI)) stored in the user identification module 8296 to verify and authenticate electronic devices 8201 in communication networks such as the first network 8298 and / or the second network 8299.

[0123] Antenna module 8297 can transmit signals and / or power to or from external devices (such as other electronic devices) or receive signals and / or power from external devices. The antenna may include a radiator made of conductive patterns formed on a substrate (such as a printed circuit board (PCB)). Antenna module 8297 may include one or more antennas. If antennas are included, communication module 8290 can select from a plurality of antennas an antenna suitable for a communication method used in a communication network such as a first network 8298 and / or a second network 8299. Signals and / or power can be transmitted or received between communication module 8290 and another electronic device via the selected antenna. In addition to antennas, other components (such as radio frequency integrated circuits (RFICs)) may be included as part of antenna module 8297.

[0124] Some components are interconnected and can exchange signals (such as commands, data, etc.) through communication methods between peripheral devices (such as buses, general purpose input and output (GPIO), serial peripheral interfaces (SPI), mobile industrial processor interfaces (MIPI), etc.).

[0125] Commands or data can be sent or received between electronic device 8201 and other electronic devices 8204 via server 8208 connected to the second network 8299. Other electronic devices 8202 and 8204 can be the same as or different types of devices as electronic device 8201. All or some operations performed by electronic device 8201 can be performed by one or more of the other electronic devices (i.e., other electronic devices 8202 and 8204, and server 8208). For example, when electronic device 8201 needs to perform a function or service, it can request one or more other electronic devices to perform that function or part or all of the service, instead of performing it itself. One or more other electronic devices receiving the request can perform additional functions or services related to the request and can send the execution results to electronic device 8201. Cloud computing, distributed computing, and / or client-server computing technologies can be used for this purpose.

[0126] Figure 15 An example of a display device applied to a mobile device according to an embodiment is shown. The mobile device 9100 may include a display device 9110, and the display device 9110 may include the driving circuitry, micro-light-emitting devices, side-reflective structures, bottom-reflective structures, etc., described above. The display device 9110 may have a foldable structure, for example, a multi-foldable structure.

[0127] Figure 16 An example of a display device according to an embodiment applied to a vehicle display device is shown. The display device may be a vehicle head-up display 9200 and may include a display 9210 provided in a region of the vehicle and an optical path changing member 9220 that converts the optical path so that the driver can see an image generated on the display 9210.

[0128] Figure 17 An example of a display device according to an embodiment applied to augmented reality glasses or virtual reality glasses is shown. Augmented reality glasses 9300 may include a projection system 9310 for forming an image and elements 9320 for guiding the image from the projection system 9310 to the user's eyes. The projection system 9310 may include the driving circuitry, micro-light-emitting devices, side-reflective structures, bottom-reflective structures, etc., as described above.

[0129] Figure 18An example of a display device applied to a sign according to an embodiment is shown. The sign 9400 can be used for outdoor advertising using a digital information display, and the advertising content can be controlled via a communication network, etc. The sign 9400 can be used, for example, by referring to... Figure 14 The described electronic device is used to achieve this.

[0130] Figure 19 An example of a display device applied to a wearable display according to an embodiment is shown. The wearable display 9500 may include the driving circuitry, micro-light-emitting devices, side-reflective structures, bottom-reflective structures, etc., as described above, and can be referenced... Figure 14 The described electronic device is used to achieve this.

[0131] The display device according to the example implementation can also be applied to various products, such as rollable TVs and stretchable displays.

[0132] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for limiting purposes. Descriptions of features or aspects within each embodiment should generally be considered applicable to other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the spirit and scope defined by the appended claims.

[0133] This application is based on and claims priority to Korean Patent Application No. 10-2021-0145860, filed on October 28, 2021, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A miniature light-emitting device, comprising: The first semiconductor layer is doped with a first impurity having a first conductivity; A light-emitting layer is disposed on the upper surface of the first semiconductor layer; A second semiconductor layer is disposed on the upper surface of the light-emitting layer, and the second semiconductor layer is doped with a second impurity having a second conductivity that is opposite to the first conductivity. An insulating layer is disposed on the upper surface of the second semiconductor layer; The first electrode is disposed on the upper surface of the insulating layer and electrically connected to the first semiconductor layer; The second electrode is disposed on the upper surface of the insulating layer and electrically connected to the second semiconductor layer; as well as An aluminum nitride layer is disposed on the lower surface of the first semiconductor layer. The aluminum nitride layer includes a flat lower surface, which is the lower surface of the micro-light-emitting device. The surface roughness of the lower surface of the aluminum nitride layer is 50 nm or less.

2. The micro light-emitting device according to claim 1, wherein the width of the micro light-emitting device is in the range of 1 μm to 100 μm.

3. The micro light-emitting device according to claim 1, wherein the width of the first semiconductor layer is greater than the thickness of the micro light-emitting device.

4. The micro light-emitting device according to claim 3, wherein the thickness of the micro light-emitting device is in the range of 2 μm to 10 μm, and the width of the first semiconductor layer is in the range of 5 μm to 50 μm.

5. The micro light-emitting device according to claim 3, wherein the width of the second semiconductor layer is greater than the thickness of the micro light-emitting device.

6. The micro light-emitting device according to claim 5, wherein the side surface of the micro light-emitting device is inclined such that the width of the first semiconductor layer is greater than the width of the second semiconductor layer.

7. The micro light-emitting device according to claim 1, wherein the surface roughness of the lower surface of the aluminum nitride layer is 10 nm or less.

8. The micro light-emitting device according to claim 1 further includes an irregular light scattering structure distributed within the first semiconductor layer.

9. The micro light-emitting device according to claim 1, wherein the aluminum nitride layer comprises a plurality of isolated grooves.

10. The micro light-emitting device of claim 9, wherein each of the plurality of isolated recesses has a dot shape, and The plurality of isolated grooves are arranged in a two-dimensional pattern on the surface of the aluminum nitride layer.

11. The micro light-emitting device of claim 9, wherein each of the plurality of isolated recesses has an annular shape, and The plurality of isolated grooves are concentrically arranged in the surface of the aluminum nitride layer.

12. The micro light-emitting device according to claim 1, wherein the second electrode is arranged at a position corresponding to the center of the second semiconductor layer in the horizontal direction, and The first electrode is positioned along the horizontal direction at a location corresponding to the edge of the second semiconductor layer.

13. The micro light-emitting device of claim 12, wherein the first electrode has a symmetrical shape surrounding the second electrode.

14. The micro light-emitting device according to claim 12, further comprising a through-hole passing through the second semiconductor layer and the light-emitting layer, The insulating layer extends to surround the sidewalls of the via, and the first electrode is configured to contact the first semiconductor layer through the via. The second electrode is configured to penetrate the insulating layer and contact the second semiconductor layer.

15. The micro light-emitting device of claim 12, further comprising a bonding diffusion prevention wall disposed between the first electrode and the second electrode.

16. The micro light-emitting device of claim 15, wherein the bonding diffusion prevention wall has a protruding shape on the upper surface of the insulating layer.

17. The micro light-emitting device of claim 15, wherein the bonding diffusion prevention wall has a groove shape.

18. The micro light-emitting device of claim 12, wherein the micro light-emitting device has a rectangular cross-section when viewed from a vertical direction, and The first electrode is arranged in two vertex regions facing each other along the diagonal direction.

19. The micro light-emitting device of claim 18, further comprising bonding pads disposed in each of two other vertex regions different from the two vertex regions, the two other vertex regions facing each other in a diagonal direction different from the diagonal direction.

20. A display device, comprising: Display substrate including driving circuitry; as well as Multiple micro light-emitting devices arranged on the display substrate, At least one of the plurality of micro light-emitting devices includes: The first semiconductor layer is doped with a first impurity having a first conductivity; A light-emitting layer is disposed on the upper surface of the first semiconductor layer; A second semiconductor layer is disposed on the upper surface of the light-emitting layer, and the second semiconductor layer is doped with a second impurity having a second conductivity that is opposite to the first conductivity. An insulating layer is disposed on the upper surface of the second semiconductor layer; The first electrode is disposed on the upper surface of the insulating layer and electrically connected to the first semiconductor layer; A second electrode is disposed on the upper surface of the insulating layer and electrically connected to the second semiconductor layer; and An aluminum nitride layer is disposed on the lower surface of the first semiconductor layer, the aluminum nitride layer having a flat lower surface, the lower surface of the aluminum nitride layer being the lower surface of at least one of the plurality of micro-light-emitting devices. The surface roughness of the lower surface of the aluminum nitride layer is 50 nm or less.

21. The display device of claim 20, wherein the second electrode is arranged at a position corresponding to the center of the second semiconductor layer in a horizontal direction, and The first electrode is positioned along the horizontal direction at a location corresponding to the edge of the second semiconductor layer.

22. The display device of claim 21, further comprising a bonding diffusion prevention wall disposed between the first electrode and the second electrode.

23. The display device according to claim 21, wherein the micro-light-emitting device has a rectangular cross-section when viewed in the vertical direction, and The first electrode is arranged in two vertex regions facing each other in the diagonal direction.

24. The display device of claim 23, further comprising bonding pads disposed in each of two other vertex regions different from the two vertex regions, the two other vertex regions facing each other in a diagonal direction different from the diagonal direction.

25. The display device of claim 20, further comprising a wavelength conversion layer configured to convert the wavelength of light emitted from the plurality of micro light-emitting devices.

26. The display device of claim 25, wherein the wavelength conversion layer comprises: The first wavelength conversion layer is configured to convert light emitted from the plurality of micro light-emitting devices into light of a first wavelength band; And a second wavelength conversion layer configured to convert light emitted from the plurality of micro light-emitting devices into light of a second wavelength band different from the first wavelength band.

27. The display device of claim 26, further comprising a color filter layer, the color filter layer comprising: A first filter is arranged to face the first wavelength conversion layer and configured to transmit light of the first wavelength band; as well as A second filter is arranged to face the second wavelength conversion layer and configured to transmit light of the second wavelength band.

28. A miniature light-emitting device, comprising: The first electrode on the first surface of the micro light-emitting device; as well as An aluminum nitride layer on a second surface opposite to the first surface of the micro-light-emitting device, the aluminum nitride layer comprising a flat lower surface, The surface roughness of the aluminum nitride layer is 50 nm or less. The lower surface of the aluminum nitride layer is the lower surface of the micro light-emitting device.

29. The micro light-emitting device of claim 28, wherein the first shape of the first electrode is radially symmetrical about the center of the micro light-emitting device.

30. The micro light-emitting device according to claim 29, further comprising a second electrode on the first surface, The second shape of the second electrode is radially symmetrical about the center of the micro light-emitting device.

31. A miniature light-emitting device, comprising: The first semiconductor layer is doped with a first impurity having a first conductivity; A light-emitting layer is disposed on the upper surface of the first semiconductor layer; A second semiconductor layer is disposed on the upper surface of the light-emitting layer, and the second semiconductor layer is doped with a second impurity having a second conductivity that is opposite to the first conductivity. An insulating layer is disposed on the upper surface of the second semiconductor layer; The first electrode is disposed on the upper surface of the insulating layer and electrically connected to the first semiconductor layer; The second electrode is disposed on the upper surface of the insulating layer and electrically connected to the second semiconductor layer; A diffusion-preventing wall is disposed between the first electrode and the second electrode; Bonding pads are arranged on the upper surface of the insulating layer; as well as An aluminum nitride layer is disposed on the lower surface of the first semiconductor layer. The aluminum nitride layer includes a flat lower surface, which is the lower surface of the micro-light-emitting device. The surface roughness of the lower surface of the aluminum nitride layer is 50 nm or less.

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