Patent Description:
Light-emitting devices (LEDs) are known as the next generation of light sources having advantages such as long lifespan, low power consumption, fast response speed, and environmental friendliness as compared with light sources of the related art, and are used in various products such as illumination devices and backlights of display apparatuses. In particular, group III nitride-based LEDs such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), and indium aluminum gallium nitride (InAlGaN) serve as light-emitting devices that output light.

<CIT> describes a semiconductor light emitting device with improved light extraction efficiency comprising a body comprising a substrate and a first and a second semiconductor layer.

<CIT> describes a semiconductor light-emitting device including a substrate with a first groove and a second groove formed therein, the substrate including a first surface and a second surface opposite to the first surface.

One or more example embodiments provide a light-emitting device having electrodes arranged on both surfaces thereof and a method of manufacturing the light-emitting device.

One or more example embodiments also provide a display apparatus including a light-emitting device having electrodes arranged on both surfaces thereof and a method of manufacturing the display apparatus.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of example embodiments of the disclosure.

According to an aspect of an example embodiment, there is provided a light-emitting device including a body including a first semiconductor layer, an active layer, and a second semiconductor layer, a first electrode and a second electrode provided on a first surface of the body, the first electrode and the second electrode being in contact with the first semiconductor layer and the second semiconductor layer, respectively, and a third electrode and a fourth electrode provided on a second surface of the body, the third electrode and the fourth electrode being in contact with the first semiconductor layer and the second semiconductor layer, respectively,
a first trench passing through the first semiconductor layer and the active layer and exposing the second semiconductor layer; and wherein the second electrode is in contact with the second semiconductor layer via the first trench, and the second electrode and the fourth electrode are not connected to each other.

The light-emitting device may further include a through hole passing through the body, wherein the first electrode is in contact with the third electrode via the through hole.

The light-emitting device may further include a first insulating layer provided on an inner wall of the through hole.

The first insulating layer may extend to the second surface of the body and is in contact with the fourth electrode.

The first electrode may be provided inside of the through hole.

The first electrode may overlap with at least a portion of the third electrode in a thickness direction of the body.

The second electrode may overlap with at least a portion of the fourth electrode in a thickness direction of the body.

The light-emitting device may further include a second insulating layer provided on an inner wall of the first trench.

The second insulating layer may extend to the first surface of the body and may be in contact with the first electrode.

The second electrode may be provided inside of the first trench.

At least one of the first electrode, the second electrode, the third electrode, and the fourth electrode may be symmetrical with respect to a central axis of the light-emitting device.

At least one of the first electrode, the second electrode, the third electrode, and the fourth electrode may have a circular cross-sectional shape.

At least one of the first electrode, the second electrode, the third electrode, and the fourth electrode may have a ring cross-sectional shape.

At least one of the first electrode, the second electrode, the third electrode, and the fourth electrode may be transparent.

The light-emitting device may further include a second trench provided between the first electrode and the second electrode in the first surface of the body.

A width of the body in a horizontal direction may be greater than a thickness of the body in a vertical direction.

According to another aspect of an example embodiment, there is provided a display apparatus including a display layer including a plurality of light-emitting devices, and a driving layer including a plurality of transistors electrically connected to the plurality of light-emitting devices, respectively, the driving layer being configured to drive the plurality of light-emitting devices, wherein at least one of the plurality of light-emitting devices includes a body including a first semiconductor layer, an active layer, and a second semiconductor layer, a first electrode and a second electrode provided on an first surface of the body, the first electrode and the second electrode being in contact with the first semiconductor layer and the second semiconductor layer, respectively, and a third electrode and a fourth electrode provided on a second surface of the body, the third electrode and the fourth electrode being in contact with the first semiconductor layer and the second semiconductor layer, respectively.

At least one of the plurality of light-emitting devices may further include a through hole passing through the body, and the first electrode may be in contact with the third electrode via the through hole.

The display apparatus may further include a first insulating layer provided on an inner wall of the through hole.

At least one of the plurality of light-emitting devices includes a first trench passing through the first semiconductor layer and the active layer and exposing the second semiconductor layer, and the second electrode may be in contact with the second semiconductor layer via the first trench.

The display apparatus may further include a second insulating layer provided on an inner wall of the first trench.

One of the first electrode and the third electrode may be electrically connected to the driving layer, and one of the second electrode and the fourth electrode may be electrically connected to the driving layer.

According to another aspect of an example embodiment, there is provided a light-emitting device including a body including a first semiconductor layer, an active layer, and a second semiconductor layer, a first electrode and a second electrode provided on a first surface of the body, the first electrode and the second electrode being in contact with the first semiconductor layer and the second semiconductor layer, respectively, a third electrode and a fourth electrode provided on a second surface of the body, the third electrode and the fourth electrode being in contact with the first semiconductor layer and the second semiconductor layer, respectively, and a first trench passing through the first semiconductor layer and the active layer and exposing the second semiconductor layer; and wherein the second electrode is in contact with the second semiconductor layer via the first trench, and the second electrode and the fourth electrode are not connected to each other, and a through hole passing through the body, wherein the first electrode is in contact with the third electrode via the through hole, and wherein the first electrode overlaps with at least a portion of the third electrode in a thickness direction of the body.

Hereinafter, example embodiments will be described in detail with reference to the accompanying drawings. The example embodiments described are merely examples, and various modifications may be possible from the example embodiments. Like reference numerals in the drawings below refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation.

Hereinafter, the expression "above" or "on" may include not only "immediately on in a contact manner" but also "on in a non-contact manner".

Although the terms "first," "second," etc. may be used to describe various elements, these terms are used only for the purpose of distinguishing one element from another. These terms do not limit the difference between materials or structures of the elements.

It will be further understood that when a part "includes" or "comprises" an element, the part may further include other elements, not excluding the other elements, unless defined otherwise.

Also, the terms ". unit," "module," etc. used in the specification indicate an unit that processes at least one function or motion, and the unit may be implemented by hardware or software, or by a combination of hardware and software.

The use of term "the" and other similar determiners may correspond to both a singular form and a plural form.

Unless orders of operations included in a method are specifically described, the operations may be performed according to appropriate orders. Also, the use of all example terms (e.g., etc.) are merely for describing the disclosure in detail and the disclosure is not limited to the examples and the example terms, unless they are not defined in the scope of the claims.

<FIG> is a cross-sectional view of a light-emitting device <NUM> according to an example embodiment, <FIG> is a diagram illustrating an upper surface of the light-emitting device <NUM> of <FIG>, and <FIG> is a diagram illustrating a lower surface of the light-emitting device <NUM> of <FIG>.

As shown in <FIG>, the light-emitting device <NUM> includes an inorganic material-based light-emitting diode, and emits light of a specific wavelength according to a material included in the light-emitting device <NUM>. The light-emitting device <NUM> includes a body <NUM> including a plurality of semiconductor layers and an electrode portion <NUM> applying an electrical signal to the body <NUM>. The light-emitting device <NUM> according to an example embodiment may be micro-sized. For example, a width W of the light-emitting device <NUM> may be less than or equal to <NUM>, or less than or equal to <NUM>.

The body <NUM> may have a flat shape in which a width W is greater than a thickness T. A cross-section parallel to a width W direction of the body <NUM>, that is, a traverse section, may be, for example, circular, elliptical and/or polygonal. A cross-section parallel to a thickness T direction of the body <NUM> may have a quadrangular shape. For example, a side cross-section of the body <NUM> may be rectangular.

The body <NUM> includes a first semiconductor layer <NUM>, an active layer <NUM>, and a second semiconductor layer <NUM>.

The first semiconductor layer <NUM> may include, for example, a p-type semiconductor. However, embodiments are not limited thereto. The first semiconductor layer <NUM> may include an n-type semiconductor. The first semiconductor layer <NUM> may include a group III-V-based p-type semiconductor, for example, p-GaN. The first semiconductor layer <NUM> may have a single-layer or multi-layer structure. For example, the first semiconductor layer <NUM> may include any one semiconductor material of InAlGaN, GaN, AlGaN, InGaN, aluminum nitride (AIN), and indium nitride (InN), and may include a semiconductor layer doped with a conductive dopant such as silicon (Si), germanium (Ge), tin (Sn), etc..

The active layer <NUM> may be arranged on a lower surface of the first semiconductor layer <NUM>. The active layer <NUM> may generate light when electrons combine with holes, and may have a multi-quantum well (MQW) structure or a single-quantum well (SQW) structure. The active layer <NUM> may include a group III-V-based semiconductor such as InGaN, GaN, AlGaN, aluminum indium gallium nitride (AlInGaN), etc. A clad layer doped with a conductive dopant may be formed on an upper portion and/or a lower portion of the active layer <NUM>. For example, the clad layer may include an AlGaN layer or an InAlGaN layer.

The second semiconductor layer <NUM> is provided on a lower surface of the active layer <NUM>, and may include a semiconductor layer of a different type from the first semiconductor layer <NUM>. For example, the second semiconductor layer <NUM> may include an n-type semiconductor layer. The second semiconductor layer <NUM> may include, for example, InAlGaN, GaN, AlGaN, and/or InGaN, and may be a semiconductor layer doped with a conductive dopant such as magnesium (Mg), etc..

The electrode portion <NUM> includes a first electrode <NUM> and a second electrode <NUM> arranged on the upper surface of the body <NUM> and in contact with the first and second semiconductor layers <NUM> and <NUM>, respectively, and further includes a third electrode <NUM> and a fourth electrode <NUM> arranged on the lower surface of the body <NUM> and in contact with the first and second semiconductor layers <NUM> and <NUM>, respectively.

As shown in <FIG>, at least one of the first to fourth electrodes <NUM>, <NUM>, <NUM>, and <NUM> may be symmetrical with respect to a central axis X of the light-emitting device <NUM>. The first electrode <NUM> may be arranged to overlap with at least a portion of the third electrode <NUM> in the thickness T direction of the body <NUM>, and the second electrode <NUM> may overlap with at least a portion of the fourth electrode <NUM> in the thickness T direction of the body <NUM>.

Because the first to fourth electrodes <NUM>, <NUM>, <NUM>, and <NUM> of a symmetric structure are arranged on both surfaces of the light-emitting device <NUM>, when transferring the light-emitting device <NUM> to another substrate, there may be no need to consider which surface of the light-emitting device <NUM> is arranged on the substrate. This may reduce transfer defects of the light-emitting device <NUM>, thereby increasing a transfer yield.

The first to fourth electrodes <NUM>, <NUM>, <NUM>, and <NUM> may be transparent electrodes. For example, the first to fourth electrodes <NUM>, <NUM>, <NUM>, and <NUM> may be formed of a transparent conductive material. Because the first to fourth electrodes <NUM>, <NUM>, <NUM>, and <NUM> are arranged on both surfaces of the light-emitting device <NUM>, light generated in the active layer <NUM> may pass through the first to fourth electrodes <NUM>, <NUM>, <NUM>, and <NUM> to be emitted to the outside. Thus, a decrease in emission efficiency of the light-emitting device <NUM> may be prevented. The first to fourth electrodes <NUM>, <NUM>, <NUM>, and <NUM> may include metal such as silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), and alloys thereof, conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium tin zinc oxide (ITZO), conductive polymer such as PEDOT, etc..

The light-emitting device <NUM> may further include a through hole TH passing through the body <NUM>, that is, through the first semiconductor layer <NUM>, the active layer <NUM>, and the second semiconductor layer <NUM>. The through hole TH may be arranged at a center of the light-emitting device <NUM>, and the first electrode <NUM> may be in contact with the third electrode <NUM> through the through hole TH. The through hole TH may have a tapered shape in which the width W narrows from the first semiconductor layer <NUM> toward the second semiconductor layer <NUM>. However, embodiments are not limited thereto. The through hole TH may have the same width W from the first semiconductor layer <NUM> toward the second semiconductor layer <NUM> or vice versa.

The light-emitting device <NUM> may further include a first insulating layer <NUM> surrounding an inner wall of the through hole TH. One end of the first insulating layer <NUM> may extend to the upper surface of the body <NUM>, and the other end of the first insulating layer <NUM> may extend to the lower surface of the body <NUM> to be in contact with the fourth electrode <NUM>. Thus, the first insulating layer <NUM> may prevent the first electrode <NUM> from being in contact with the active layer <NUM> and the second semiconductor layer <NUM> via the through hole TH, and may prevent the third electrode <NUM> from being in contact with the second semiconductor layer <NUM>.

The light emitting-device <NUM> further includes a first trench T1 passing through only a portion of the body <NUM>. The first trench T1 passes through the first semiconductor layer <NUM> and the active layer <NUM> to expose the second semiconductor layer <NUM>. In addition, the second electrode <NUM> is in contact with the second semiconductor layer <NUM> via the first trench T1. An edge region of the second electrode <NUM> may be arranged on the upper surface of the body <NUM>, and a middle region of the second electrode <NUM> may be in contact with the second semiconductor layer <NUM> via the first trench T1.

In the drawings, two first trenches T1 are arranged at equal intervals with the through hole TH therebetween. However, embodiments are not limited thereto. There may be two or more first trenches T1. For example, when there are three first trenches T1, the three trenches T1 may be arranged to be rotationally symmetrical by <NUM> degrees with respect to the central axis X of the light-emitting device <NUM>.

The light-emitting device <NUM> may further include a second insulating layer <NUM> surrounding the inner wall of the first trench T1. The second insulating layer <NUM> may include a hole that exposes the second semiconductor layer <NUM> while surrounding the inner wall of the first trench T1, and may extend to the upper surface of the body <NUM> to be in contact with the first electrode <NUM>. Thus, the second insulating layer <NUM> may cause a portion of the second electrode <NUM> to be in contact with the second semiconductor layer <NUM> through the first trench T1, and may prevent the remaining portion of the second electrode <NUM> from being in contact with the first semiconductor layer <NUM> and the active layer <NUM>.

The first electrode <NUM> may have a circular shape that protrudes convexly along the through hole TH, and the second electrode <NUM> may have a ring shape that protrudes convexly along the first trench T1. The third electrode <NUM> may have a circular shape, and the fourth electrode <NUM> may have a ring shape.

<FIG> are diagrams illustrating a method of manufacturing the light-emitting device <NUM> according to an example embodiment.

As shown in <FIG>, a second semiconductor material layer 113a, an active material layer 112a, and a first semiconductor material layer 111a may be sequentially formed on a first substrate <NUM>. The first substrate <NUM> may be a substrate for growing the light-emitting device <NUM>. The first substrate <NUM> may include various materials used in a general semiconductor process. For example, a silicon substrate or a sapphire substrate may be used as the first substrate <NUM>.

The second semiconductor material layer 113a, the active material layer 112a, and the first semiconductor material layer 111a may be formed by methods such as metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), etc..

As shown in <FIG>, the second semiconductor material layer 113a, the active material layer 112a, and the first semiconductor material layer 111a are patterned to form the body <NUM> having the through hole TH and the first trench T1. The first substrate <NUM> may be exposed by the through hole TH, and the second semiconductor material layer 113a is exposed by the first trench T1. Cross-sections of the through hole TH and the first trench T1 may be circular, elliptical and/or polygonal. In <FIG>, one through hole TH and two first trenches T1 per body <NUM> are shown, but embodiments are not limited thereto. The numbers of through holes TH and first trenches T1 may vary.

As shown in <FIG>, a first insulating pattern <NUM> may be formed on the body <NUM>. The first insulating pattern <NUM> may be formed on the upper surface of the body <NUM>. The first insulating pattern <NUM> may extend to a side surface of the through hole TH and a side surface of the first trench T1, the first substrate <NUM> may be exposed by the through hole TH, and the second semiconductor layer <NUM> is exposed by the first trench T1. A portion of the first insulating pattern <NUM> may be part of the first insulating layer <NUM> of <FIG>, and the remaining portion of the first insulating pattern <NUM> may be part of the second insulating layer <NUM>.

As shown in <FIG>, the first and second electrodes <NUM> and <NUM> are formed on the body <NUM>. The first electrode <NUM> may be formed to pass through bottom and side surfaces of the through hole TH and extend to the upper surface of the body <NUM>. The second electrode <NUM> is formed to pass through bottom and side surfaces of the first trench T1 and extend to the upper surface of the body <NUM>, while being spaced apart from the first electrode <NUM>.

As shown in <FIG>, the body <NUM> having the first and second electrodes <NUM> and <NUM> formed thereon may be transferred to a second substrate <NUM> to expose the lower surface of the body <NUM>. The second substrate <NUM> may include an insulating material such as glass, organic polymer, crystal, etc. Further, the second substrate <NUM> may include a flexible material to bend or fold, and may have a single-layer structure or a multi-layer structure.

For example, the second substrate <NUM> is arranged on the upper surface of the body <NUM>. Then, after the upper and lower positions of the first and second substrates <NUM> and <NUM> are changed, the first substrate <NUM> may be removed from the body <NUM> by, for example, a laser lift-off method, a chemical lift-off method, or a grinding method.

As shown in <FIG>, a second insulating pattern <NUM> may be formed on the lower surface of the body <NUM>. The second insulating pattern <NUM> may be formed such that a portion of the second semiconductor layer <NUM> and a portion of the first electrode <NUM> are exposed. The second insulating pattern <NUM> may be part of the first and second insulating layers <NUM> and <NUM> described with reference to <FIG>.

As shown in <FIG>, the third and fourth electrodes <NUM> and <NUM> are formed on the lower surface of the body <NUM>. The third electrode <NUM> may be formed to overlap with at least a portion of the first electrode <NUM> in the thickness T direction of the body <NUM> while being in contact with the first electrode <NUM>. The fourth electrode <NUM> is formed to be in contact with the second semiconductor layer <NUM> while being spaced apart from the third electrode <NUM> in the width W direction of the body <NUM>. Further, the fourth electrode <NUM> may be formed to overlap with at least a portion of the second electrode <NUM> in the thickness T direction of the body <NUM>. The light-emitting device <NUM> completed may be separated from the second substrate <NUM> to be transferred to another substrate.

As described above, because the first to fourth electrodes <NUM>, <NUM>, <NUM>, and <NUM> are arranged on both the upper surface and the lower surface of the body <NUM>, there may be no need to consider the positions of the electrodes when transferring the light-emitting device <NUM> to another substrate. Thus, a defective rate of transfer of the light-emitting device <NUM> may be reduced.

<FIG> is a diagram illustrating a light-emitting device 100a according to another example embodiment. Compared to <FIG> and <FIG>, the through hole TH of the light-emitting device 100a of <FIG> may be filled with a first electrode 121a, and the first trench T1 may be filled with a second electrode 122a. When the through hole TH is emptied in the manufacturing process of the light-emitting device 100a, a connecting portion between the first electrode 121a and a third electrode 123a may be formed of a thin insulating layer and an electrode thin-film such that mechanical strength may be weakened. By filling the through hole TH with the first electrode 121a, the weakening of the strength of the light-emitting device 100a due to the through hole TH may be prevented or reduced. Similarly, the inside of the first trench T1 being filled with the second electrode 122a may prevent the weakening of the strength of the light-emitting device 100a.

<FIG> is a diagram illustrating a light-emitting device 100b according to another example embodiment. Upon comparing <FIG> and <FIG>, the light-emitting device 100b of <FIG> may further include an insulating material <NUM> that fills spaces in the through hole TH and the first trench T1. When the through hole TH is filled with transparent insulating material <NUM>, an emission area may be increased as compared with an example embodiment in which the through hole TH is filled with an electrode material, and thus, a decrease in emission efficiency may be prevented or reduced.

The through hole TH may not be arranged on a central axis X of the light-emitting device 100b. <FIG> is a diagram illustrating a light-emitting device 100c according to another example embodiment. As shown in <FIG>, the through hole TH may be arranged in an edge region of the light-emitting device 100c, and a first electrode 121b may have a ring shape. A second electrode 122b may be arranged on a central axis X of the light-emitting device 100c, and may have a circular shape. Because the through hole TH is arranged on the edge of the light-emitting device 100c, a larger emission area of the active layer <NUM> may be secured.

<FIG> is a diagram illustrating a light-emitting device 100d according to another example embodiment. The light-emitting device 100d of <FIG> may further include a second trench T2 between the first electrode 121b and the second electrode 122b. The second trench T2 may have a ring shape. The second trench T2 may prevent the first and second electrodes 121b and 122b from being short-circuited. In <FIG>, the second trench T2 is arranged between the first and second electrodes 121b and 122b, but embodiments are not limited thereto. The second trench T2 may be arranged between the third and fourth electrodes <NUM> and <NUM>. Further, the second trench T2 may have a ring shape, or may have a shape including a plurality of grooves H that are apart from each other.

<FIG> is a diagram illustrating a light-emitting device 100e according to another example embodiment. A second insulating layer 140a included in the light-emitting device 100e of <FIG> may surround a side surface of the body <NUM>. The second insulating layer 140a may not only electrically insulate between the second and fourth electrodes <NUM> and <NUM> and the body <NUM>, but may also be a protective film for protecting the body <NUM> from the outside.

<FIG> is a diagram illustrating a light-emitting device 100f according to another example embodiment. A body 110a included in the light-emitting device 100f of <FIG> may have an increasing width from an upper portion toward a lower portion thereof. As described above, by varying widths of the upper surface and the lower surface of the body 110f, when transferring the light-emitting device 100f, the light-emitting device 100f may be induced to be transferred in a specific direction. For example, in a case where a width of the body 110f increases from the upper portion toward the lower portion thereof, when transferring the light-emitting device 100f, the third and fourth electrodes <NUM> and <NUM> of the light-emitting device 100f may be induced to be arranged in the lower portion of the light-emitting device 100f.

As described above, because the electrodes are arranged on both the upper surface and the lower surface of the body, the light-emitting device <NUM>, 100a, 100b, 100c, 100d. 100e, 100f may be transferred without considering the positions of the electrodes included in the light-emitting device. Thus, a defective rate of the light-emitting device <NUM>, 100a, 100b, 100c, 100d. 100e, 100f during transfer may be reduced.

<FIG> are diagrams illustrating a method of transferring the light-emitting device <NUM> to a transfer substrate <NUM>, according to an example embodiment.

As shown in <FIG>, a liquid <NUM> may be supplied to the transfer substrate <NUM>. The transfer substrate <NUM> may be a single body including a plurality of grooves H or a substrate having a single mold structure. The transfer substrate <NUM> may include, for example, an organic material, such as silicon, glass, sapphire, and polymer, an inorganic material, and/or a metal, and may be manufactured by photoresist patterning, etching, molding, etc., but the present disclosure is not limited thereto. When the light-emitting device <NUM> is transferred to the transfer substrate <NUM>, the groove H may serve a role of guiding the transfer of the light-emitting device <NUM>.

The groove H may have a cross-sectional area greater than the area of the light-emitting device <NUM> to accommodate the light-emitting device <NUM>. The groove H may have an area capable of containing only one light-emitting device <NUM>, or may have an area capable of containing a plurality of light-emitting devices <NUM>. The groove H may have a shape similar to the cross-section of the light-emitting device <NUM>, for example, a circular cross-section or a polygonal cross-section. The groove H may have a depth less or greater than the thickness of the light-emitting device <NUM>, for example, a depth less than twice the thickness of the light-emitting device <NUM>, or a depth in a range of <NUM> to <NUM> times the thickness of the light-emitting device <NUM>. A bottom surface of the groove H may have a roughness of <NUM> or less.

As the liquid <NUM>, any type of liquid may be used as long as the liquid <NUM> does not corrode or damage the light-emitting device <NUM>. The liquid <NUM> may include, for example, one or a plurality of combinations from the group including water, ethanol, alcohol, polyol, ketone, halocarbon, acetone, a flux, and an organic solvent. The organic solvent may include, for example, isopropyl alcohol (IPA). The liquid <NUM> that may be used is not limited thereto, and various modifications may be made.

A method of supplying the liquid <NUM> to the transfer substrate <NUM> may include, for example, a spraying method, a dispensing method, an inkjet dot method, a method of spilling the liquid <NUM> onto the transfer substrate <NUM>, etc., which will be described later. The amount of the liquid <NUM> that is supplied may be variously adjusted to rightly fit the groove H or to spill over from the groove H.

As shown in <FIG>, a plurality of light-emitting devices <NUM> may be supplied to the transfer substrate <NUM>. The light-emitting device <NUM> may be directly sprayed onto the transfer substrate <NUM> without another liquid <NUM>, or may be supplied while being included in a suspension. A method of supplying the light-emitting device <NUM> included in the suspension may include various methods such as a dispensing method for dropping the liquid <NUM>, an inkjet dot method for discharging the liquid <NUM>, such as a printing method, a method of spilling the suspension onto the transfer substrate <NUM>, etc..

The supplying of the liquid <NUM> to the groove H of the transfer substrate <NUM> and the supplying of the light-emitting device <NUM> to the transfer substrate <NUM> may be performed in the reverse order to the order described with reference to <FIG> and <FIG>. Further, the supplying of the liquid <NUM> to the groove H of the transfer substrate <NUM> and the supplying of the light-emitting device <NUM> to the transfer substrate <NUM> may be performed simultaneously in one operation. For example, by supplying the suspension including the light-emitting device <NUM> to the transfer substrate <NUM>, the liquid <NUM> and the light-emitting device <NUM> may be simultaneously supplied to the transfer substrate <NUM>.

As shown in <FIG>, the transfer substrate <NUM> is scanned using an absorber <NUM> capable of absorbing the liquid <NUM>. The absorber <NUM> may include all kinds of materials capable of absorbing the liquid <NUM>, and a shape or a structure of the absorber <NUM> is not limited to particular types. The absorber <NUM> may include, for example, fabric, tissue, polyester fiber, paper, a wiper, etc. Although the absorber <NUM> may be used independently without an auxiliary device, in some embodiments, the absorber <NUM> may be coupled to a support to facilitate scanning of the transfer substrate <NUM>. The support may have various forms and structures suitable for scanning the transfer substrate <NUM>. The support may have, for example, a shape such as a rod, a blade, a plate, or a wiper. The absorber <NUM> may be provided on a surface of the support, or may surround a perimeter of the support.

The scanning may include absorbing the liquid <NUM> while the absorber <NUM> contacts the transfer substrate <NUM> and passes through the plurality of grooves H. The scanning may be performed, for example, by various methods such as a sliding method, a rotating method, a translating movement method, a reciprocating movement method, a rolling method, a spinning method, and/or a rubbing method of the absorber <NUM>, and may include both a regular method and an irregular method.

The scanning may be performed by moving the transfer substrate <NUM> instead of moving the absorber <NUM>, and the scanning of the transfer substrate <NUM> may also be performed by a sliding, rotating, translating, reciprocating, rolling, spinning, and/or rubbing method, etc. The scanning may be performed via cooperation of the absorber <NUM> and the transfer substrate <NUM>.

In the scanning process, the light-emitting device <NUM> may be seated in the groove H due to a difference in surface energy or a complementary shape between the groove H and the light-emitting device <NUM>. Because the light-emitting device <NUM> has electrodes arranged on both the upper surface and the lower surface thereof, the light-emitting device <NUM> may be seated in a forward direction or in a reverse direction.

After the absorber <NUM> scans the transfer substrate <NUM>, a dummy light-emitting device remaining in the transfer substrate <NUM> may be removed without entering the groove H. The operations described with reference to <FIG> may be repeated, and through these operations, the light-emitting device <NUM> may be rapidly transferred to the transfer substrate <NUM>.

<FIG> is a diagram illustrating, as a related example, a state in which light-emitting devices LED1 and LED2 having electrodes arranged on only one surface thereof are transferred to the transfer substrate <NUM>. Due to a difference in surface energy between the transfer substrate <NUM> and the light-emitting devices LED1 and LED2, the light-emitting devices LED1 and LED2 may be seated in the groove H. In general, the electrodes of the light-emitting device LED1 may be arranged towards the outside of the groove H of the transfer substrate <NUM>. This is because an upper surface of the transfer substrate <NUM> except for the groove H and the electrodes of the light-emitting device LED1 may be hydrophobic, while the bottom surface of the groove H of the transfer substrate <NUM> may be hydrophilic. However, when adjustment of the difference in the surface energy fails, the electrodes of the light-emitting device LED2 may be arranged towards the bottom surface of the groove H. The light-emitting device LED2 is defectively transferred, and may need to be repaired.

However, because the light-emitting device <NUM> according to an example embodiment has electrodes arranged on both surfaces thereof, defects may not occur even when the light-emitting device <NUM> is transferred upside down. Thus, a repair operation may be omitted, and costs and time may be saved.

In <FIG>, the light-emitting device <NUM> is transferred by a fluidic self-assembly method. However, embodiments are not limited thereto, and the light-emitting device <NUM> according to an example embodiment may be transferred by various methods such as a pick-and-place method, etc..

The light-emitting devices <NUM>, 100a, 100b, 100c, 100d, 100e, and 100f described above may be used as emission sources of various devices. For example, the light-emitting devices <NUM>, 100a, 100b, 100c, 100d, 100e, and 100f may be applied to an illumination device or a self-emission display apparatus.

<FIG> are diagrams illustrating a process of manufacturing a display apparatus <NUM> by using the light-emitting device <NUM>, according to an example embodiment.

Referring to <FIG>, a target substrate <NUM> may be aligned on the transfer substrate <NUM> to which the light-emitting device <NUM> is transferred. The light-emitting device <NUM> may be transferred to the transfer substrate <NUM> by a fluidic self-assembly method, a pick-and-place method, etc. The target substrate <NUM> may include a substrate <NUM> and a driving layer <NUM>. The substrate <NUM> may include an insulating material such as glass, organic polymer, crystal, etc. Further, the substrate <NUM> may include a flexible material to bend or fold, and may have a single-layer structure or a multi-layer structure. The driving layer <NUM> may include a transistor driving the light-emitting device <NUM>, an electrode pattern, etc. The electrodes of the light-emitting device <NUM> may be arranged to face the electrode pattern formed on the target substrate <NUM>. The electrodes of the light-emitting device <NUM> facing the electrode pattern may be the first and second electrodes <NUM> and <NUM>, or may be the third and fourth electrodes <NUM> and <NUM>.

As shown in <FIG>, the light-emitting device <NUM> may be transferred to the target substrate <NUM>. For example, the light-emitting device <NUM> may be transferred to the target substrate <NUM> by a bonding method. After aligning the transfer substrate <NUM> and the target substrate <NUM>, the light-emitting device <NUM> may be bonded to the target substrate <NUM> using thermo-compression, ultrasonic, or light (e.g., laser and UV). For example, when thermo-compression is applied between the electrodes of the light-emitting device <NUM> and the electrode pattern of the target substrate <NUM>, The electrodes of the light-emitting device <NUM> and the electrode pattern of the target substrate 410may be compressed in proportion to the pressure and temperature and bonded to the electrodes of the light-emitting device <NUM> and the electrode pattern of the target substrate <NUM>.

After transferring the light-emitting device <NUM> to the target substrate <NUM>, the transfer substrate <NUM> is removed. Then, as shown in <FIG>, the position of the target substrate <NUM> may be changed such that the light-emitting device <NUM> may be arranged on the top.

When the transfer substrate <NUM> itself is a target substrate including a driving layer, the light-emitting device <NUM> may be bonded to the transfer substrate <NUM> without an additional transfer.

As shown in <FIG>, a planarization layer <NUM> may be formed on the light-emitting device <NUM> and the target substrate <NUM>. The planarization layer <NUM> may cover the light-emitting device <NUM> and have a flat upper surface. The planarization layer <NUM> may alleviate a step generated by components arranged below the planarization layer <NUM>, and may prevent oxygen and moisture from penetrating into the light-emitting device <NUM>. The planarization layer <NUM> may be formed of an insulating material. The planarization layer <NUM> may include an organic insulating film (e.g., acrylic or silicon-based polymer) or an inorganic insulating film (e.g., silicon oxide (SiO<NUM>), silicon nitride (SiN), aluminum oxide (Al<NUM>O<NUM>), or titanium oxide (TiO<NUM>)), but embodiments are not limited thereto. The planarization layer <NUM> may be formed of a plurality of insulating materials having different dielectric constants in a multi-layered structure.

As shown in <FIG>, a color conversion layer <NUM> may be formed on the planarization layer <NUM>. When the light-emitting device <NUM> emits light of the same wavelength, the color conversion layer <NUM> may include a first color conversion pattern <NUM>, a second color conversion pattern <NUM>, and a third color conversion pattern <NUM> that convert the light generated in the light-emitting device <NUM> into light of a predetermined wavelength. Here, each of the first to third color conversion patterns <NUM>, <NUM>, and <NUM> may correspond to each sub-pixel. For example, the first color conversion pattern <NUM> may correspond to a first sub-pixel SP1, and the second color conversion pattern <NUM> may correspond to a second sub-pixel SP2, and the third color conversion pattern 435may correspond to a third sub-pixel SP3. The color conversion layer <NUM> may be formed by a photolithography method.

In <FIG>, the light-emitting device <NUM> emits light of the same wavelength, but embodiments are not limited thereto. When each of the light-emitting devices <NUM> functions as a sub-pixel by emitting different light, for example, red, blue, and green light, a color conversion layer may not be formed.

In the display apparatus <NUM> manufactured through the process illustrated in <FIG>, lower electrodes of the light-emitting device <NUM> and the driving layer are electrically connected, but embodiments are not limited thereto. Upper electrodes of the light-emitting device <NUM> and the driving layer may also be electrically connected.

<FIG> are diagrams illustrating a process of manufacturing a display apparatus <NUM> by using the light-emitting device <NUM>, according to another example embodiment.

As shown in <FIG>, a driving layer <NUM> may be formed on a substrate <NUM>. The driving layer <NUM> may include a thin-film transistor (TFT), a first electrode pattern EL1, a capacitor, etc..

As shown in <FIG>, a flexible partition <NUM> having a groove H may be formed on the driving layer <NUM>. The flexible partition <NUM> may include a polymer layer <NUM> and a metal layer <NUM>. The metal layer <NUM> may be electrically connected to the first electrode pattern EL1 of the driving layer <NUM> via a hole h formed in the polymer layer <NUM>. The substrate <NUM>, the driving layer <NUM>, and the flexible partition <NUM> may form a transfer substrate.

As shown in <FIG>, the light-emitting device <NUM> may be transferred in the groove H. The transfer of the light-emitting device <NUM> may be the same as shown in <FIG>, but embodiments are not limited thereto. The light-emitting devices 100a, 100b, 100c, 100d, 100e, and 100f shown in <FIG> may also be transferred. The light-emitting device <NUM> may be transferred by, for example, a fluidic self-assembly method or a pick-and-place method.

As shown in <FIG>, an insulating layer <NUM> covering the light-emitting device <NUM> and at least a portion of the flexible partition <NUM> may be formed, and a second electrode pattern EL2 electrically connecting the upper electrodes of the light-emitting device <NUM> and the driving layer <NUM> may be formed. The second electrode pattern EL2 may be electrically connected to the first electrode pattern EL1 of the driving layer <NUM> via the metal layer <NUM> of the flexible partition <NUM>. The insulating layer <NUM> may prevent oxygen and moisture from penetrating into the light-emitting device <NUM>.

Then, as shown in <FIG>, a planarization layer <NUM> may be formed on the insulating layer <NUM> and the second electrode pattern EL2. A color conversion layer may be further formed.

<FIG> is a diagram illustrating a display apparatus <NUM> including the light-emitting device <NUM>, according to another example embodiment. The display apparatus <NUM> of <FIG> may include a third electrode pattern EL3 arranged under the light-emitting device <NUM> and a fourth electrode pattern EL4 arranged on the light-emitting device <NUM>. The third electrode pattern EL3 may be electrically connected to any one of the lower electrodes of the light-emitting device <NUM>, and the fourth electrode pattern EL4 may be electrically connected to any one of the upper electrodes of the light-emitting device <NUM>. For example, the third electrode pattern EL3 may be electrically connected to the third electrode <NUM> of the light-emitting device <NUM> without being electrically connected to the fourth electrode <NUM>. The fourth electrode pattern EL4 may be electrically connected to the second electrode <NUM> without being electrically connected to the first electrode <NUM>.

Because the electrodes are arranged on both surfaces of the light-emitting device <NUM>, a display apparatus may be manufactured by selectively using the lower electrodes and the upper electrodes of the light-emitting device <NUM>, and thus, a method of manufacturing the display apparatus may be diversified.

A display apparatus including the light-emitting devices <NUM>, 100a, 100b, 100c, 100d, 100e, and 100f described above may be employed in various electronic devices. For example, the display apparatus may be applied to a television, a laptop, a mobile phone, a smartphone, a smart pad (PD), a portable media player (PMP), personal digital assistants (PDA), navigation, various wearable devices such as a smart watch and a head mounted display, etc..

Claim 1:
A light-emitting device comprising:
a body comprising a first semiconductor layer (<NUM>), an active layer (<NUM>), and a second semiconductor layer (<NUM>);
a first electrode (<NUM>) and a second electrode (<NUM>) provided on a first surface of the body, the first electrode and the second electrode being in contact with the first semiconductor layer and the second semiconductor layer, respectively;
a third electrode (<NUM>) and a fourth electrode (<NUM>) provided on a second surface of the body, the third electrode and the fourth electrode being in contact with the first semiconductor layer and the second semiconductor layer, respectively;
a first trench (T1) passing through the first semiconductor layer (<NUM>) and the active layer (<NUM>) and exposing the second semiconductor layer (<NUM>); and
wherein the second electrode (<NUM>) is in contact with the second semiconductor layer (<NUM>) via the first trench (T1), and characterised in that the second electrode (<NUM>) and the fourth electrode (<NUM>) are not connected to each other.