Patent Publication Number: US-2022230999-A1

Title: Display device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 16/968,065, filed on Aug. 6, 2020, which was filed as the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2018/007641, filed on Jul. 5, 2018, which claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2018-0015246, filed on Feb. 7, 2018, the entire contents of all these applications are all hereby expressly incorporated by reference into the present application. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present disclosure relates to a display device. 
     Discussion of the Related Art 
     Recently, a flat panel display device having excellent features such as thin and light designs, and low power consumption has been widely developed and used in various fields. 
     A liquid crystal display (LCD) is widely used in various areas, from small-sized portable terminals to large-sized televisions, because of its high display quality and features such as thin and lightweight designs, and low power consumption. 
     An organic light emitting diode (OLED) display device (hereinafter, “OLED”) is a device that emits light. Electrons and holes (electron holes) are injected into an emissive (or light-emitting) layer formed between a cathode which is an electron injection electrode and an anode which is a hole injection electrode. As the electrons and holes recombine, electron-hole pairs are created, forming an exciton. The emissive layer emits light as the excited state decays. Such an OLED device has advantages such as flexible nature, color capability, and low power consumption. More specifically, the OLED device can be formed even on a flexible substrate such as plastic, has excellent color naturalness due to its characteristics of self-emission and can be driven at a low voltage (less than 10V). 
     However, a liquid crystal displays (LCD) has some drawbacks, such as a not-so-fast response time and high energy consumption as it lowers efficiency of backlight unit with high efficiency. In the case of an organic light emitting diode (OLED), organics have much shorter lifetimes of up to around 2 years as they are vulnerable to reliability, and have low mass-production yield. 
     In order to obviate these problems, a new display device in which micro LEDs are aligned in each pixel region (or area) has been developed. 
     However, in a large display device using such micro LEDs, there is a difficulty in aligning each of the micro LEDs to a lower wiring on which the respective pixel regions are located, due to their small size. 
     In the related art, micro LEDs are self-aligned to a lower wiring by a capillary force. However, as the capillary force is too weak, a possibility of self-alignment is low. As a result, many micro LEDs are wasted, which leads to a decrease in yield. 
     Further, in the related art, one micro LED should be aligned in one pixel region, but a plurality of micro LEDs may be arranged in one pixel region. 
     SUMMARY OF THE DISCLOSURE 
     An aspect of the present disclosure is to provide a display device having a plurality of light-emitting devices aligned on a substrate in an accurate and efficient manner. 
     Embodiments disclosed herein provide a display device that may include a lower substrate on which a lower electrode is disposed, a flat layer disposed on the lower substrate and having a plurality of holes, a plurality of light-emitting devices disposed in each of the plurality of holes, a magnetic portion disposed on the lower substrate and having magnetic properties, and a reaction portion disposed at each of the light-emitting devices and forming an attractive force with the magnetic portion. A magnetization direction of the magnetic portion may be perpendicular to the lower substrate. 
     In one embodiment, the magnetic portion may be made of a ferromagnetic material, and the reaction portion may be made of a paramagnetic material. 
     In one embodiment, each of the light-emitting devices may include a first electrode electrically connected to the lower electrode and having a plurality of layers, a first conductive semiconductor layer disposed on the first electrode, an active layer disposed on the first conductive semiconductor layer, and a second conductive semiconductor layer disposed on the active layer. The reaction portion may be any one of the plurality of layers constituting the first electrode. 
     In one embodiment, the first electrode may include a first metal layer in contact with the first conductive semiconductor layer, and a second metal layer in contact with the lower electrode. The reaction portion may be disposed between the first electrode layer and the second electrode layer. 
     In one embodiment, the reaction portion may be made of any one of Ni, Fe, Mo, and Co, or an Ni—Mo—Fe alloy or an Ni—Cr—Mo—Fe alloy. 
     In one embodiment, resistivity of the first and second metal layers may be less than resistivity of the reaction portion. 
     In one embodiment, the lower electrode may include a plurality of layers, and the magnetic portion may be any one of the plurality of layers constituting the lower electrode. 
     In one embodiment, the magnetic portion may be made of an Sm—Co alloy. 
     In one embodiment, a thickness of the magnetic portion may be 20 to 1000 nm. 
     In one embodiment, the present disclosure may further include a flat layer covering the lower substrate and having a plurality of holes, and the magnetic portion may be disposed to overlap a corresponding hole of the plurality of holes. 
     The embodiments of the present disclosure may provide at least one or more of the following benefits or advantages. A possibility that two or more light-emitting devices are arranged in one pixel region may be reduced due to mating (or matching) of a light-emitting structure and a substrate. 
     A defective or improper electrical connection between a light-emitting device and a lower wiring may be reduced even when the light-emitting structure is rotated on an axis perpendicular to a lower substrate due to a shape of the light-emitting structure. 
     In addition, a magnetic portion and a reaction portion are provided on the lower substrate and the light-emitting device, thereby increasing a possibility of proper alignment of the light-emitting device using a capillary force and a magnetic force. 
     Also, a high-speed screen may be implemented with a fast response speed by disposing an inorganic light-emitting device in a pixel region. 
     Further, a separate backlight unit is not required, thereby providing excellent luminance and high efficiency. 
     Moreover, the light-emitting device is an inorganic material, which is advantageous in terms of a long lifespan. 
     Furthermore, the light-emitting devices may be disposed in the unit of pixels, making it suitable to be implemented as an active type. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a display device according to a first embodiment of the present disclosure; 
         FIG. 2  is a planar view of the display device according to the first embodiment illustrated in  FIG. 1 ; 
         FIG. 3  is a planar view of a lower substrate according to the first embodiment of the present disclosure; 
         FIG. 4  is a cross-sectional view taken along line “A-A” of the lower substrate illustrated in  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of a light-emitting device according to the first embodiment of the present disclosure; 
         FIG. 6  is a planar view of the light-emitting device according to the first embodiment of the present disclosure, 
         FIGS. 7A and 7B  are views illustrating modified examples of positioning partition walls according to the first embodiment of the present disclosure; 
         FIGS. 8A and 8B  are views illustrating modified examples of the light-emitting device according to the first embodiment of the present disclosure; 
         FIGS. 9A to 9D  are views illustrating a method of fabricating the display device according to the first embodiment of the present disclosure; 
         FIG. 10  is a cross-sectional view of a display device according to a second embodiment of the present disclosure; 
         FIG. 11  is a planar view of a lower substrate according to the second embodiment of the present disclosure; 
         FIG. 12  is a cross-sectional view of a light-emitting device according to the second embodiment of the present disclosure; 
         FIG. 13  is a cross-sectional view of a display device according to a third embodiment of the present disclosure; 
         FIG. 14A  is a cross-sectional view of a display device according to a fourth embodiment of the present disclosure; 
         FIG. 14B  is a cross-sectional view of a light-emitting device according to the fourth embodiment of the present disclosure; 
         FIGS. 15A to 15C  are views illustrating a method of fabricating the display device according to the second embodiment of the present disclosure; 
         FIG. 16  is a cross-sectional view of a display device according to the present disclosure; 
         FIG. 17  is a cross-sectional view of a lower wiring according to the present disclosure; 
         FIG. 18  is a cross-sectional view of a light-emitting device according to the present disclosure; 
         FIG. 19  is a bottom view of the light-emitting device according to the present disclosure; 
         FIGS. 20A to 20C  are cross-sectional views illustrating a method of fabricating the display device according to the present disclosure; and 
         FIG. 21  is a conceptual view illustrating a transfer process using holes having different shapes. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The advantages and features of the present disclosure will become better understood with reference to the following detailed description of embodiments taken in conjunction with the accompanying drawings. Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions and the like can be made without departing from the spirit of the disclosure, and these are, therefore, considered to be within the scope of the disclosure, as defined in the following claims. Like reference numerals refer to like components throughout the specification. 
     Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, term such as “below” can encompass both an orientation of above and below. The device may be otherwise oriented at other orientations, and the spatially relative descriptors used herein are interpreted accordingly. 
     In will be understood that the terminology used herein is for the purpose of describing the embodiments herein and is not intended to limit the present disclosure. A singular representation may include a plural representation as far as it represents a definitely different meaning from the context. Terms such as “comprises” and/or “comprising” used herein should be understood that they are intended to indicate the existence of a feature, a number, a step, a constituent element, a component or a combination thereof disclosed in the specification, and it may also be understood that the existence or additional possibility of one or more other features, numbers, steps, constituent elements, components or combinations thereof are not excluded in advance. 
     In the drawings, thickness or dimensions of each layer are exaggerated, omitted, or schematically illustrated for the sake of convenience and clarity. In addition, dimensions of constituent components and areas do not entirely reflect the actual dimensions and areas. 
     In addition, angles and directions mentioned for the purpose of describing a structure of a display device in the embodiments disclosed herein are based on those illustrated in the drawings. In describing the structures constituting the display device in the specification, if reference points and positional relationships with respect to angles are not explicitly referred to, reference is made to the related drawings. 
     Hereinafter, the embodiments will be described in more detail with reference to the drawings. 
       FIG. 1  is a cross-sectional view of a display device according to a first embodiment of the present disclosure,  FIG. 2  is a planar view of the display device according to the first embodiment illustrated in  FIG. 1 ,  FIG. 3  is planar view of a lower substrate according to the first embodiment of the present disclosure, and  FIG. 4  is a cross-sectional view taken along line “A-A” of the lower substrate illustrated in  FIG. 3 . 
     Referring to  FIGS. 1 to 4 , a display device  1  according to the first embodiment includes a lower substrate  10  on which lower wiring  11  is disposed, and at least two light-emitting devices (or elements)  100  each having a first electrode  121  electrically connected to the lower wiring  11  and a light-emitting structure  110  configured to generate light. 
     In addition, the display device  1  according to the first embodiment further includes a second electrode  122  located on a second conductive semiconductor layer  113 , an upper wiring  20  electrically connected to the second electrode  122 , and a color substrate  30  disposed on the light-emitting device  100  to convert a wavelength of light generated from the light-emitting device  100 . 
     The lower substrate  10  may be implemented as a film made of an insulating material. For example, the lower substrate  10  may be made of a transparent glass material, or may be made of a transparent plastic or a polymer film having high flexibility. 
     The lower wiring  11  is disposed on the lower substrate  10 . The lower wiring  11  is electrically connected to the light-emitting device  100  to supply driving power to the light-emitting device  100 . The lower wiring  11  located on the lower substrate  10  is provided at a position that corresponds to the light-emitting device  100 . More specifically, the lower wiring  11  is disposed in a line shape on a plane (or flat surface), as shown in  FIG. 3 , so as to supply driving power to a plurality of light-emitting devices  100 . The light-emitting devices  100  are arranged with a constant pitch on the lower wiring  11  that is disposed in the line shape. Alternatively, the lower wiring  11  is disposed in a dot shape on a plane. 
     The lower wiring  11  may include a conductive material, and include a metal selected from, such as In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, Cr, Mo, Nb, Al, Ni, Cu, and WTi, or an alloy thereof, and may be formed as a single layer or multiple layers. Further, the lower wiring  11  may be made of a light transmissive material that includes at least one of ITO, IZO (In—ZnO), GZO (Ga—ZnO), AZO (Al—ZnO), AGZO (Al—Ga ZnO), IGZO (In—Ga ZnO), IrO x , RuO x , RuO x /ITO, Ni/IrO x /Au, and Ni/IrO x /Au/ITO. 
     The lower wiring  11  is formed such that the conductive material described above is coated or deposited on the lower substrate  10  by using a deposition method such as sputtering. Then, a metal layer may be patterned by a photolithography process and an etching process using a mask. 
     The lower wirings  11  may be arranged to intersect each other and a switching element (not shown) may be located at a point of the intersection. The lower wiring  11  may be disposed in consideration of a pixel region (or area) P, which will be described hereinafter. 
     The lower wiring  11  is electrically connected to the first electrode  121  of the light-emitting device  100 , and a metal bonding layer  13  is provided to reinforce adhesion between the lower wiring  11  and the first electrode  121 . 
     The metal bonding layer  13  is disposed on the lower wiring  11  to correspond to each of the pixel regions P in which the respective light-emitting devices  100  are located. The metal bonding layer  13  is used for joining the lower wiring  11  and the first electrode  121  together. 
     In addition, the metal bonding layer  13  may be made of a material that produces a capillary force on the first electrode  121 . The plurality of light-emitting devices  100  is aligned on the lower wiring  11  to correspond to the respective pixel regions P by the capillary force acting between the metal bonding layer  13  and the first electrode  121 . 
     In detail, the lower substrate  10  on which the metal bonding layer  13  is disposed is put into a solution containing a larger number of light-emitting devices  100  than that of the pixel regions P while applying vibration. Then, the light-emitting devices  100  are self-aligned by the capillary force between the metal bonding layer  13  and the first electrode  121 . 
     When heat is applied to the metal bonding layer  13 , the metal bonding layer  13  is melted, allowing the first electrode  121  and the lower wiring  11  to be joined together. The metal bonding layer  13  has a melting point temperature of 45° C. to 300° C. A metal solder having 150° C. to 300° C. of melting point temperature is used to withstand driving conditions of the display device and temperature of post-processes. Thus, self-alignment is performed at the melting point temperature of the metal bonding layer  13 . More preferably, the melting point temperature of the metal bonding layer  13  is lower than a melting point temperature of the first electrode  121 . 
     The metal bonding layer  13  includes a conductive material. For example, the metal bonding layer  13  may be at least one element of Sn, Ag, Cu, Pb, Al, Bi, Cd, Fe, In, Ni, Sb, Zn, Co, and Au, or a component of these elements with eight-component systems or less. More preferably, the metal bonding layer  13  may be at least one element of Cu, Pb, Al, Fe and Ni, or a component of these elements. 
     The metal bonding layer  13  is formed on the lower wiring  11  by using a deposition method such as sputtering. Then, the metal layer may be patterned by a photolithography process and an etching process using a mask. 
     When the metal bonding layer  13  is melted, the metal bonding layer  13  disposed on the lower wiring  11  expands more than a set or predetermined size. As a result, two or more light-emitting devices  100  may be coupled to the metal bonding layer  13 . In order to prevent this, a positioning partition wall  12  is provided at an upper portion of the lower substrate  10 . 
     The positioning partition wall  12  defines a space in which the metal bonding layer  13  is accommodated. In addition, the positioning partition wall  12  determines a position in which the first electrode  121  of the light-emitting device  100  is aligned. The positioning partition wall  12  serves as a wall that prevents the metal bonding layer  13  from expanding beyond a predetermined size. In addition, the positioning partition wall  12  holds the shape of the metal bonding layer  13 . Accordingly, the metal bonding layer  13  has a shape corresponding to a shape of the light-emitting device  100 , thereby facilitating alignment of the light-emitting device  100 , and preventing two or more light-emitting devices from being coupled to one metal bonding layer  13 . 
     Moreover, a central region S 1  of the light-emitting structure  110  is inserted in a space defined by the positioning partition wall  12 . The space defined by the positioning partition wall  12  has a shape that allows the central region S 1  to be inserted. When the central region S 1  is inserted into the space defined by the positioning partition wall  12 , the likelihood of proper (or successful) alignment of the light-emitting device  100  is increased. A center of the light-emitting device  100  is aligned with a center of the metal bonding layer  13  even though the light-emitting device  100  is brought into contact with the metal bonding layer  130  by a capillary force due to a mating (or matching) of the central region S 1  with the positioning partition wall  12 . 
     In more detail, the positioning partition wall  12  has a shape that accommodates a part (or portion) of the lower wiring  11  and protrudes upward than the lower wiring  11 . For example, as illustrated in  FIG. 4 , the positioning partition wall  12  may be a wall protruding upward from the lower substrate  10 . Alternatively, the positioning partition wall  12  may be recessed downward from an upper portion of the lower substrate  10 . However, considering arrangement of the lower wiring  11  on the lower substrate  10 , the positioning partition wall  12  may have a wall shape protruding from the lower substrate  10 . 
     In particular, referring to  FIG. 3 , the positioning partition wall  12  is disposed on the lower substrate  10  at a position corresponding to each of the pixel regions P in which the respective light-emitting devices  100  are to be located, so as to determine a region where the first electrode  121  and the metal bonding layer  13  are joined together. The metal bonding layer  13  is accommodated in a space defined by the positioning partition wall  12  on a plane. 
     The positioning partition wall  12  has a shape of a closed space on a plane. The positioning partition wall  12  is disposed to surround the metal bonding layer  13  on a plane. The positioning partition wall  12  has a ring shape on a plane. 
     More specifically, in order to prevent misalignment of the light-emitting device  100 , an inner space defined by the positioning partition wall  12  is formed to correspond to the central region S 1  of the light-emitting structure  110 , which will be described hereinafter. The inner space defined by the positioning partition wall  12  has a circular shape. A diameter d 1  of the inner space defined by the positioning partition wall  12  is greater than a diameter d 2  of the central region S 1 . The diameter d 1  of the inner space defined by the positioning partition wall  12  may correspond to 90% to 120% of the diameter d 2  of the central region S 1 . As another example, the positioning partition wall  12  is continuously (or consecutively) disposed on a boundary line that surrounds the central region S 1 , when viewed from above. 
     The positioning partition wall  12  is made of a resin material having electrical insulation properties. 
     The upper wiring  20  supplies driving (or electric) power to the light-emitting device  100 . The upper wiring  20  supplies electric power of opposite polarity to the lower wiring  11 . 
     In detail, the upper wiring  20  is electrically connected to the second electrode  122  of the light-emitting device  100 . The upper wiring  20  is located on the second electrode  122 . The upper wiring  20  is disposed to at least vertically overlap the second electrode  122 . In addition, the upper wiring  20  is disposed in a line shape on a plane. 
     The upper wiring  20  may include a conductive material, and include a metal selected from, such as In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, Cr, Mo, Nb, Al, Ni, Cu, and WTi, or an alloy thereof, and may be formed as a single layer or multiple layers. More preferably, the upper wiring  20  may be made of a material that transmits light generated from the light-emitting device  100  located below. For example, the upper wiring  20  may include at least one of ITO, IZO (In—ZnO), GZO (Ga—ZnO), AZO (Al—ZnO), AGZO (Al—Ga ZnO), IGZO (In—Ga ZnO), IrO x , RuO x , RuO x /ITO, Ni/IrO x /Au, and Ni/IrO x /Au/ITO. 
     The upper wiring  20  is formed such that the conductive material described above is coated or deposited on the second electrode  122  using a deposition method such as sputtering. Then, the metal layer may be patterned via a photolithography process and an etching process using a mask. 
     In order to arrange the upper wiring  20  having the line shape, a molding material  40  is filled in an air gap (or void) between each of the light-emitting devices  100 . An upper surface of the light-emitting device  100  is flattened (or planarized) by the molding material  40 . The molding material  40  is made of transparent silicone that transmits light, for example. 
     Referring to  FIG. 2 , the color substrate  30  is disposed on the light-emitting device  100  so as to convert the wavelength of light generated by the light-emitting device  100 . In addition, one region of the color substrate  30  shields light, and another region transmits light, so as to be divided into a plurality of pixel regions P and non-pixel regions P′. 
     The plurality of pixel regions P may be arranged in a matrix type having rows and columns. A black matrix  31  is disposed on the non-pixel regions P′ of the color substrate  30  with a constant interval to define the pixel regions P. 
     For example, the color substrate  30  may include the black matrix  31  and a color filter  32 . 
     The black matrix  31  is formed on the color substrate  30 . The black matrix  31  divides the region of the color substrate  30  into a plurality of pixel regions P where the color filters  32  are to be provided, and prevents light interference and external light reflection between adjacent pixel regions P. 
     A plurality of color filters  32  (R, G, B) is located at the pixel regions P that correspond to a space between the black matrices  31 . 
     The color filters  32  are provided in the pixel regions P divided by the black matrix  31  to be classified into red (R), green (G), and blue (B), so as to transmit red light, green light, and blue light, respectively. The red, green, and blue color filters  32  (R, G, and B) for representing colors may be arranged in a stripe shape along respective column directions. 
     The black matrix  31  may include a material that blocks light, for example, a non-light transmitting synthetic resin. 
     The color filter  32  may be disposed to vertically overlap the plurality of light-emitting devices  100  (see  FIG. 1 ). Further, the black matrix  31  may be disposed without vertically overlapping the plurality of light-emitting devices  100 . Accordingly, most of the light generated from the light-emitting devices  100  is emitted to the outside through the color filter  32 , thereby improving efficiency and brightness of the display device  1 . 
     The color filter  32  may include a phosphor that converts the wavelength of light generated in the light-emitting devices  100 . For example, at least one phosphor may be selected according to a wavelength of light to be realized (or achieved). 
     Such a phosphor may be one of a blue light emitting phosphor, a blue-green light emitting phosphor, a green light emitting phosphor, a yellow-green light emitting phosphor, a yellow light emitting phosphor, a yellow-red light emitting phosphor, an orange light emitting phosphor, and a red light emitting phosphor according to the wavelength of light emitted from the light-emitting device  100 . 
     In other words, the phosphor may be excited by light having first light emitted from the light-emitting device  100  to generate second light. 
     For example, when the light-emitting device  100  is a blue light-emitting diode and a phosphor is a yellow phosphor, the yellow phosphor may be excited by blue light to emit yellow light. 
     Such phosphors may be known phosphors, such as YAG-based, TAG-based, sulfide-based, silicate-based, aluminate-based, nitride-based, carbide-based, nitridosilicate-based, borate-based, fluoride-based, and phosphate-based phosphors. 
     Alternatively, the color substrate  30  may not be provided, but each of the light-emitting devices  100  may be configured to emit red, green, and blue light instead. However, in this case, it may be difficult to align each of the light-emitting devices  100  in a manner of corresponding to a color of the respective pixel region P. 
       FIG. 5  is a cross-sectional view of a light-emitting device according to the first embodiment of the present disclosure, and  FIG. 6  is a planar view of the light-emitting device according to the first embodiment of the present disclosure. 
     The plurality of light-emitting devices  100  is located at the lower wiring  11  to correspond to the respective pixel regions P. In detail, the light-emitting devices  100  are aligned and adhered onto the respective metal bonding layers  13  located corresponding to each pixel region P. 
     The light-emitting device  100  includes the first electrode  121 , the second electrode  122 , and the light-emitting structure  110  that generates light. 
     The light-emitting device  100  may be an inorganic semiconductor selected from semiconductor materials having a composition formula In x Al y  Ga 1-x-y N (0=x=1, 0=y=1, 0=x+y=1). 
     A Liquid Crystal Display (LCD) has some drawbacks, for example, a response time is not fast, causing huge power consumption as it lowers efficiency of a backlight unit having high efficiency. Further, Organic Light Emitting Diodes (OLEDs) have shorter lifetimes of up to around 2 years, and have very low mass-production yield. 
     In this embodiment, a high-speed screen with a fast response speed may be realized by disposing the inorganic light-emitting devices  100  in the pixel regions P. In addition, a backlight unit is not separately required, thereby achieving excellent luminance (or brightness) and high efficiency. 
     Further, the light-emitting device  100  is an inorganic material, and thereby to have a long lifespan. Moreover, the light-emitting devices  100  may be arranged in the unit of pixels, making it suitable for implementing as an active type. 
     The light-emitting device  100  may emit an ultraviolet ray (UV) or blue light. In the case of light having a short wavelength, luminance is excellent, thereby achieving a light of high luminance with a low voltage. 
     The light-emitting device  100  may be formed using a metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma chemical vapor deposition (PECVD), Molecular Beam Epitaxy (MBE), Hydride Vapor Phase Epitaxy (HVPE), sputtering, and the like, but the method is not limited thereto. 
     For example, the light-emitting structure  110  includes a first conductive semiconductor layer  111 , an active layer  112  disposed on the first conductive semiconductor layer  111 , and the second conductive semiconductor layer  113  located on the active layer  112 . 
     The first conductive semiconductor layer  111  may be formed of a semiconductor compound and be doped with a first conductive dopant. For example, the first conductive semiconductor layer  111  may be implemented as an n-type semiconductor layer to provide electrons to the active layer  112 . The first conductive semiconductor layer  111  may be selected from semiconductor materials, such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN, and AlInN, that have a composition formula of In x Al y Ga 1-x-y N (0=x=1, 0=y=1, 0=x+y=1), and may be doped with a n-type dopant, such as Si, Ge, Sn, Se, and Te. 
     The active layer  112  may be disposed on the first conductive semiconductor layer  111 . The active layer  112  may have any one of a single quantum well structure, a multiple quantum well structure, a quantum-wire structure, and a quantum dot structure by using a compound semiconductor material of Group 3 to 5 elements. 
     When the active layer  112  consists of a quantum well structure, it may have a single or multiple quantum well structure with a well layer having a composition formula of In x Al y Ga 1-x-y N (0=x=1, 0=y=1, 0=x+y=1) and a barrier layer having a composition formula of In a Al b Ga 1-a-b N (0=a=1, 0=b=1, 0=a+b=1), for example. The well layer may be formed of a material having a smaller band gap than the barrier layer. 
     In addition, when the active layer  112  has a multiple quantum well structure, each of well layers (not shown) may have a different In content and a different band gap, which will be described hereinafter with reference to  FIG. 2 . 
     A conductive clad layer (not shown) may be formed on and/or beneath the active layer  112 . The conductive clad layer (not shown) may be implemented as a semiconductor, and have a larger band gap than the active layer  112 . For example, the conductive clad layer (not shown) may include AlGaN. 
     The second conductive semiconductor layer  113  may be formed of a semiconductor compound to inject holes into the active layer  112 , and be doped with a second conductive dopant. For example, the second conductive semiconductor layer  113  may be implemented as a p-type semiconductor layer. The second conductive semiconductor layer  113  may be selected from semiconductor materials, such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN, and AlInN, that have a composition formula of In x Al y Ga 1-x-y N (0=x=1, 0=y=1, 0=x+y=1), and may be doped with a p-type dopant such as Mg, Zn, Ca, Sr, and Ba. 
     Meanwhile, an intermediate layer (not shown) may be formed between the active layer  112  and the second conductive semiconductor layer  113 . The intermediate layer (not shown) may prevent electrons, injected into the active layer  112  from the first conductive semiconductor layer  111 , from flowing to the second conductive semiconductor layer  113  without being recombined with holes at the active layer  112  when a high current is applied. The intermediate layer (not shown) has a relatively larger band gap than the active layer  112 , and thus the electrons injected from the first conductive semiconductor layer  111  may be prevented from being injected into the second conductive semiconductor layer  113  without being recombined with the holes at the active layer  112 . Accordingly, the possibility of recombination of electrons and holes at the active layer  112  may be increased and a leakage current may be prevented. 
     In addition, the first conductive semiconductor layer  111  may be implemented as a p-type semiconductor layer, the second conductive semiconductor layer  113  may be implemented as an n-type semiconductor layer, and a third semiconductor layer (not shown) including an n-type or a p-type semiconductor layer opposite to polarity of the second conductive semiconductor layer  113  may be formed on the second conductive semiconductor layer  113 . Accordingly, the light-emitting device may have at least one of np, pn, npn, and pnp junction structures. The light-emitting device  100  of this embodiment is configured as a vertical type in which electrodes are formed at upper and lower portions of the light-emitting structure  110 , the first conductive semiconductor layer  111  is implemented as a p-type semiconductor layer, and the second conductive semiconductor layer  113  is implemented as an n-type semiconductor layer. 
     Meanwhile, the first electrode  121  electrically connected to the first conductive semiconductor layer  111  may be disposed on the first conductive semiconductor layer  111 . For example, the first electrode  121  may be formed at a lower portion of the first conductive semiconductor layer  111 . The first electrode  121  and the lower wiring  11  are adhered together by the metal bonding layer  13 . 
     Further, the second electrode  122  electrically connected to the second conductive semiconductor layer  113  may be disposed on the second conductive semiconductor layer  113 . More specifically, the second electrode  122  is located on the second conductive semiconductor layer  113 . 
     The first electrode  121  and the second electrode  122  may be formed by a deposition method such as sputtering. However, the present disclosure is not limited thereto. 
     Meanwhile, the first electrode  121  and the second electrode  122  may be made of a conductive material, and may include a metal selected from, such as In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, Cr, Mo, Nb, Al, Ni, Cu, and WTi, or an alloy thereof, and may be formed as a single layer or multiple layers. However, the present disclosure is not limited thereto. More preferably, the first electrode  121  is made of any one element of Au, Pt, and Ag, or an alloy thereof. 
     In addition, a bonding layer (not shown) that joins the first electrode  121  and the first conductive semiconductor layer  111  together is formed between the first electrode  121  and the first conductive semiconductor layer  111 . The bonding layer (not shown) may include any one of a PbSn alloy, an AuGe alloy, an AuBe alloy, an AuSn alloy, an Snln alloy, and a Pdln alloy. 
     Moreover, the first electrode  121  may further include a reflective layer  123  that is conductive and reflects light incident from the active layer  112 . 
     When light generated in the active layer  112  travels to the lower substrate  10 , the light is reflected by the reflective layer  123  without being absorbed by the first electrode  121 , thereby preventing a decrease in luminance and brightness, due to light absorbed by the first electrode  121 . 
     The light-emitting structure  110  includes the central region S 1  in which the first electrode  121  is located and the peripheral region S 2  that surrounds the central region S 1 . 
     When viewed from the bottom, the central region S 1  is disposed at a middle of the light-emitting structure  110  and is located inside the peripheral region S 2 . The peripheral region S 2  defines a closed space for accommodating the central region S 1  therein. 
     The central region S 1  and the peripheral region S 2  may have step differences. In detail, the central region S 1  has a step that protrudes downward from the peripheral region S 2 . An area where the first electrode  121  is located is smaller than a lower area of the light-emitting structure  110 , and the first electrode  121  is located inward from a lower edge of the light-emitting structure  110 . This prevents a plurality of light-emitting devices  100  from being aligned in one pixel region P. In other words, even when side (or lateral) surfaces of the plurality of light-emitting devices  100  are in contact with each other on a plane, a diameter d 2  of the central region S 1  in which the first electrode  121  is located is less than a width d 3  of the light-emitting structure  110 , and the metal bonding layer  13  is formed to correspond to the first electrode  121 , thereby lowering a possibility of the plurality of light-emitting devices  100  coupled to one metal bonding layer  13 . 
     The step between the central region S 1  and the peripheral region S 2  may be formed by disposing a semiconductor layer beneath the light-emitting structure  110 , or by etching the peripheral region S 2  of the light-emitting structure  110  upward. 
     The step between a lower surface of the central region S 1  and a lower surface of the peripheral region S 2  is not limited. The step between the lower surface of the central region S 1  and the lower surface of the peripheral region S 2  may be, preferably, 500 nm to 7000 nm. This is because if the step between the lower surface of the central region S 1  and the lower surface of the peripheral region S 2  is less than 500 nm, the central region S 1  is easily separated or displaced even when inserted into the positioning partition wall  12 , whereas the step therebetween is greater than 7000 nm, efficiency of the light-emitting device  100  is reduced. Here, the first electrode  121  is disposed at the lower surface of the central region S 1 . 
     In more detail, at least a side (or lateral) surface of the first conductive semiconductor layer  111  is exposed to a boundary between the central region S 1  and the peripheral region S 2 . More preferably, at least the side surface of the first conductive semiconductor layer  111 , a side surface of the active layer  112  and a part (or portion) of a side surface of the second conductive semiconductor layer  113  are exposed to the boundary between the central region S 1  and the peripheral region S 2 . The central region S 1  may be formed by etching the lower edge of the light-emitting structure  110 . 
     A planar width or diameter of the light-emitting structure  110  is greater than a planar width or diameter of the central region S 1 . The planar width or diameter of the central region S 1  may be, preferably, 50% to 85% of those of the light-emitting structure  110 . The width of the peripheral region S 2  is equally formed along a circumference of the central region S 1 . 
     When viewed from the bottom, the light-emitting structure  110  has a shape of any one of a rectangular shape, a polygonal shape, and a circular shape. When the light-emitting structure  110  is densely disposed on a plane, a shape with a high porosity is more suitable. Therefore, a planar shape of the light-emitting structure  110  may be a hexagonal or more polygonal shape, or a circular shape. 
     When viewed from the bottom, the central region S 1  may have a shape of any one of a rectangular shape, a polygonal shape, and a circular shape. The central region S 1  may have a planar shape that corresponds to the planar shape of the light-emitting structure  110 , or have a different planar shape. However, in order to prevent the plurality of light-emitting devices  100  from being arranged in one pixel region P, the planar shape of the central region S 1  may be, preferably, the same as the planar shape of the light-emitting structure  110 . Accordingly, it is preferable that the central region S 1  disposed at the center of the lower surface of the light-emitting structure  110  has a hexagonal or more polygonal shape, or a circular shape. 
     A shape of the peripheral region S 2  viewed from below is determined by the shapes of the central region S 1  and the light-emitting structure  110 . The peripheral region S 2  has a ring shape when viewed from the bottom. The peripheral region S 2  serves as a buffer for preventing an electrode of the light-emitting device  100  located around the pixel region P from being brought into contact with the metal bonding layer  13  or the lower wiring  11  of the pixel region P. 
     In addition, the light-emitting device  100  further includes an insulating layer  124 . The insulating layer  124  prevents the lower wiring  11  from being electrically connected to other layers, except the first conductive semiconductor layer  111 . In detail, the insulating layer  124  covers a side surface of the light-emitting structure  110 . More specifically, the insulating layer  124  is disposed to surround the circumference of the central region S 1  and the peripheral region S 2 , and is disposed at a lower portion of the peripheral region S 2 . The insulating layer  124  includes a resin material made of an electrically insulating material. 
       FIGS. 7A and 7B  are views illustrating modified examples of the positioning partition walls according to the first embodiment of the present disclosure. 
     Referring to  FIG. 7A , the positioning partition wall  12  in  FIG. 7A  has a different shape to the positioning partition wall  12  of the first embodiment. The positioning partition wall  12  according to the modified example of  FIG. 7A  has a polygonal shape on a plane. In detail, the planar shape of the positioning partition wall  12  is rectangular. Here, the central region S 1  is also formed in a rectangular planar shape. 
     Referring to  FIG. 7B , the positioning partition wall  12  in  FIG. 7B  has a different shape to the positioning partition wall  12  of the first embodiment. The positioning partition wall  12  according to the modified example of  FIG. 7B  is disposed on a boundary line surrounding the central region S 1  in a non-continuous (or discontinuous) manner, when viewed from above. 
       FIGS. 8A and 8B  are views illustrating modified examples of the light-emitting device according to the first embodiment of the present disclosure. 
     Referring to  FIG. 8A , the light-emitting device  100  in  FIG. 8A  has a different shape to the light-emitting device  100  of the first embodiment. The light-emitting structure  110  according to the modified example of  FIG. 8A  has a polygonal shape on a plane. More specifically, the planar shape of the light-emitting structure  110  is rectangular. 
     In addition, the central region S 1  has the rectangular planar shape that corresponds to the planar shape of the light-emitting structure  110 . 
     Referring to  FIG. 8B , the light-emitting device  100  in  FIG. 8B  has a different shape to the light-emitting device  100  according to the first embodiment. In the modified example of  FIG. 8B , the light-emitting structure  110  has a rectangular shape on a plane, and the central region S 1  has a circular shape on a plane. 
       FIGS. 9A to 9D  are views illustrating a method of fabricating the display device according to the first embodiment of the present disclosure. 
     Referring to  FIG. 9A , the lower substrate  10  having the lower wiring  11  disposed thereon is prepared. The positioning partition wall  12  is formed on the lower substrate  10 . The metal bonding layer  13  is located inside a space defined by the positioning partition wall  12 . 
     Referring to  FIGS. 9B and 9C , numerous light-emitting devices  100  are aligned with respective pixel regions P by a capillary force acting between the metal bonding layer  13  and the first electrode  121  of the light-emitting device  100 . In detail, the lower substrate  10  provided with the metal bonding layer  13  is put into a container containing a solution with the numerous light-emitting devices  100 , and vibration is applied. In the solution, the light-emitting devices  100  are aligned with the respective pixel regions P by the capillary force between the metal bonding layer  13  and the first electrode  121  of the light-emitting device  100 . At this time, heat is applied to melt the metal bonding layer  13 . The melted metal boding layer  10  allows the first electrode  121  to be adhered onto the lower wiring  11 . 
     Here, the light-emitting device  100  is put into the solution in a state that the first electrode  121  and the light-emitting structure  110  are only formed. This is because when the second electrode  122  is formed, a defect occurs, namely, the second electrode  122  and the lower wiring  11  are connected to each other. 
     Shapes of the positioning partition wall  12  and the central region S 1  may prevent two or more of the light-emitting devices  100  from being aligned in one pixel region P. The central region S 1  of the light-emitting structure  110  may be easily inserted into the positioning partition wall  12  even when the central region S 1  has a circular shape to allow the light-emitting structure  110  to be rotated. 
     Referring to  FIG. 9D , the second electrode  122  is formed on the light-emitting device  100 . A molding material is filled in an air gap (or void) between the light-emitting devices  100  to be flattened. Then, the upper wiring  20  and the color substrate  30  are disposed on the light-emitting device  100 . 
       FIG. 10  is a cross-sectional view of a display device according to a second embodiment of the present disclosure,  FIG. 11  is a planar view of a lower substrate according to the second embodiment of the present disclosure, and  FIG. 12  is a cross-sectional view of a light-emitting device according to the second embodiment of the present disclosure. 
     Referring to  FIGS. 10 to 12 , a display device  1 A according to the second embodiment further includes a magnetic portion (or part) located at any one of the lower substrate  10  and a light-emitting device  100 A, and a reaction portion (or part) located at the remaining one, as compared to the first embodiment. Hereinafter, the difference from the first embodiment will be mainly discussed, and a description the same as the first embodiment will be omitted. 
     The display device  1 A according to the second embodiment includes the lower substrate  10  on which at least two lower wirings  11  are disposed, at least two light-emitting devices  100 A each having the first electrode  121  electrically connected to the lower wiring  11  and the light-emitting structure  110  that generates light, and the magnetic portion located on any one of the light-emitting device  100 A and the lower substrate  10 , and the reaction portion located on the remaining one, so as to be attracted by the magnetic portion. 
     In the second embodiment, the positioning partition wall  12  of the first embodiment is not provided. In the second embodiment, one light-emitting device  100 A is self-aligned in one pixel region P by a magnetic force acting between the magnetic portion and the reaction portion. 
     The metal bonding layer  13  is disposed on the lower wiring  11  in an area where the light-emitting device  100 A is to be located, as in the first embodiment. 
     The light-emitting device  100 A of the second embodiment has no distinction between the central region S 1  and the peripheral region S 2  at a lower portion the light-emitting device  100 A, as compared with the light-emitting device  100  of the first embodiment. That is, the lower portion of the light-emitting device  100 A is formed flat. 
     In particular, referring to  FIG. 12 , the light-emitting device  100 A of the second embodiment includes the light-emitting structure  110 , the first electrode  121 , and the second electrode  122 . The display device  1 A of the second embodiment further includes the upper wiring  20  electrically connected to the second electrode  122  and the color substrate  30  disposed on the light-emitting device  100 A. 
     The light-emitting structure  110  includes the first conductive semiconductor layer  111 , the active layer  112  located on the first conductive semiconductor layer  111 , and the second conductive semiconductor layer  113  located on the active layer  112 . 
     The first electrode  121  is exposed to a lower portion of the first conductive semiconductor layer  111 , and the second electrode  122  is exposed to an upper portion of the second conductive semiconductor layer  113 . 
     The insulating layer  124  is also provided in the second embodiment. The insulating layer  124  is disposed to surround at least a side surface of the light-emitting structure  110 . 
     The plurality of light-emitting devices  100 A is aligned on the lower wiring  11  of the lower substrate  10  by an attractive force between the magnetic portion and the reaction portion. 
     The magnetic portion is a material having a magnetic force. For example, the magnetic portion includes a magnet. The magnetic portion includes a permanent magnet or a temporary magnet. The magnetic portion is located at any one of the lower substrate  10  and the light-emitting device  100 A. However, in case the magnetic portion is implemented as a magnet, the magnetic portion should be located on the lower substrate  10  since it is difficult to place the magnet on the light-emitting device  100 A. 
     Alignment positions of the light-emitting devices  100 A on the lower substrate  10  are defined by these magnetic portions. The magnetic portions are arranged on the lower substrate  10  corresponding to the respective pixel regions P. More specifically, the magnetic portions are arranged to vertically overlap a part of the lower wirings  11  vertically overlapping the respective pixel regions P. 
     The magnetic portion may be located beneath the lower wiring  11 . That is, each of the magnetic portions may be located between the lower wiring  11  and the lower substrate  10 . In addition, the magnetic portions may be located inside the lower substrate  10 , or located at a lower surface of the lower substrate  10 . For example, as illustrated in  FIG. 10 , the magnetic portion may include a first magnetic portion  14  buried or embedded in the lower substrate  10 . 
     When an area of the magnetic portion is too large, a plurality of light-emitting devices  100 A may be arranged in one pixel region P. Thus, each of the magnetic portions has a planar shape that corresponds to the first electrode  121 . In detail, the magnetic portions have a circular planar shape as illustrated in  FIG. 11 . In addition, the area and width of the magnetic portions are less than those of the first electrode  121 . 
     Here, the metal bonding layer  13  is disposed to vertically overlap the magnetic portion. The magnetic portion vertically overlaps a middle portion of the metal bonding layer  13 , but does not overlap edges of the metal bonding layer  13 . 
     The reaction portion reacts with a magnetic force of the magnetic portion, so that an attractive force is generated therebetween. 
     For example, the reaction portion includes a magnet so that an attractive force is acted on the magnetic portion. More specifically, the magnetic portion is a magnet having a first polarity, and the reaction portion is a magnet having a second polarity opposite to the first polarity. 
     As another example, the reaction portion includes a magnetic metal so that an attractive force is acted on the magnetic portion. The magnetic metal is a metal that includes a magnetic body that is attracted by a magnetic force of the magnet. The magnetic metal includes a ferromagnetic material. In detail, the reaction portion includes any one element of Ni, Cr, Mo, and Fe, or is an alloy of these elements. 
     The reaction portion is located at the remaining one of the lower substrate  10  and the light-emitting device  100 A. As the reaction portion is made of a magnetic metal, the reaction portion may be, preferably, located at the light-emitting device  100 A. 
     As the reaction portion is a conductor, it is configured to be electrically connected to the first electrode  121  and/or the second electrode  122  during a growth process of the light-emitting device  100 A so as to prevent an electrical short circuit. More specifically, the reaction portion may be formed by a deposition method such as sputtering together with the first electrode  121  and/or the second electrode  122 . 
     In particular, referring to  FIG. 12 , the reaction portion is implemented as a first magnetic electrode  131  located between the first electrode  121  and the first conductive semiconductor layer  111 . Accordingly, the first magnetic electrode  131  is located beneath or below the first conductive semiconductor layer  111 , and the first electrode  121  is located beneath the first magnetic electrode  131 . 
     A bonding layer  134  may be provided between the first magnetic electrode  131  and the first conductive semiconductor layer  111  to improve a binding (or coupling) force between the first magnetic electrode  131  and the first conductive semiconductor layer  111 . The bonding layer  134  is at least one element of Sn, Ag, Cu, Pb, Al, Bi, Cd, Fe, In, Ni, Sb, Zn, Co, and Au, or a compound of these elements. Further, the bonding layer  134  and the first magnetic electrode  131  may be implemented as a single layer. 
     The first magnetic electrode  131  is an electrically conductive material, and includes a magnetic metal attracted by a magnetic force of the magnetic portion. The first magnetic electrode  131  includes any one element of Ni, Cr, Mo, and Fe, or an alloy of these elements. 
       FIG. 13  is a cross-sectional view of a display device according to a third embodiment of the present disclosure. 
     Referring to  FIG. 13 , a display device  1 B according to the third embodiment further includes a second magnetic portion  15  and a second magnetic electrode  132 , as compared to the second embodiment. 
     The magnetic portion may include the first magnetic portion  14  and the second magnetic portion  15 , or include only the second magnetic portion  15  or only the first magnetic portion  14 . In  FIG. 13 , the magnetic portion includes the first magnetic portion  14  and the second magnetic portion  15 . 
     When a magnetic force of the magnetic portion is weak, a possibility of proper alignment of the light-emitting device  100 A decreases, and thus a plurality of magnetic portions may be provided. That is, a plurality of magnetic portions is provided in one pixel region P. 
     The second magnetic portion  15  is located at the lower surface of the lower substrate  10 . In detail, the second magnetic portion  15  is disposed to vertically overlap the first magnetic portion  14 , and has a shape and a size corresponding to a shape and a size of the first magnetic portion  14 . 
     The reaction portion may include the first magnetic electrode  131  and the second magnetic electrode  132 , or include only the first magnetic electrode  131 . In  FIG. 13 , the reaction portion includes the first magnetic electrode  131  and the second magnetic electrode  132 . 
     The second magnetic electrode  132  is electrically connected to the second electrode  122 . The second magnetic electrode  132  is located between the second electrode  122  and the second conductive semiconductor layer  113 . The second magnetic electrode  132  is used to provide more magnetic force when the magnetic force is insufficient with the first magnetic electrode  131  alone. 
       FIG. 14A  is a cross-sectional view of a display device according to a fourth embodiment of the present disclosure, and  FIG. 14B  is a cross-sectional view of a light-emitting device according to the fourth embodiment of the present disclosure. 
     A display device  1 C according to the fourth embodiment has a different shape to the display device  1 A of the second embodiment. 
     In a light-emitting device  100 C of the fourth embodiment, the light-emitting structure  110  is divided into a central region S 1  and a peripheral region S 2 , and the first electrode  121  and the first magnetic electrode  131  are located at the central region S 1 . The central region S 1  and the peripheral region S 2  are the same as those described in the first embodiment. 
     Accordingly, a possibility of a plurality of light-emitting devices  100 C located in one pixel region P is reduced. 
       FIG. 15A to 15C  are views illustrating a method of fabricating the display device according to the second embodiment of the present disclosure. 
     Referring to  15 A, first, the lower substrate  10  having the lower wiring  11  disposed thereon is prepared. The first magnetic portion  14  is formed on the lower substrate  10 . The metal bonding layer  13  is disposed on the lower wiring  11  corresponding to the pixel region P. 
     Referring to  FIGS. 15B and 15C , numerous light-emitting devices  100 A are aligned with respective pixel regions P by a capillary force between the metal bonding layer  13  and the first electrode  121  of the light-emitting device  100 A, and an attractive force between the first magnetic portion  14  and the first magnetic electrode  131  of the light-emitting device  100 A. More specifically, the lower substrate  10  is put into a container including a solution containing the numerous light-emitting devices  100 A, and vibration is applied thereto. Then, the light-emitting devices  100 A are aligned to the respective pixel regions P in the solution by the magnetic force and the capillary force. Here, heat is applied to melt the metal bonding layer  13 . The melted boding layer  13  allows the first electrode  121  to be adhered onto the lower wiring  11 . 
     At this time, the light-emitting device  100 A is put into the solution in a state that the first electrode  121 , the first magnetic electrode  131 , and the light-emitting structure  110  are only formed. This is because when the second electrode  122  is formed, a defect occurs, namely, the second electrode  122  and the lower wiring  11  are connected to each other. 
     Then, the second electrode  122  is formed on the light-emitting device  100 A. A molding material is filled in an air gap between the light-emitting devices  100 A to be flattened. Thereafter, the upper wiring  20  and the color substrate  30  are disposed on the light-emitting device  100 A. 
     Meanwhile, the present disclosure provides a structure for improving accuracy of transferring light-emitting devices by using the fabrication method according to  FIGS. 9A to 9D . Hereinafter, for the sake of convenience, a description will be given that the magnetic portion is disposed on the lower substrate and the reaction portion is disposed on the light-emitting device. 
       FIG. 16  is a cross-sectional view of a display device according to the present disclosure,  FIG. 17  is a cross-sectional view of a lower wiring,  FIG. 18  is a cross-sectional view of a light-emitting device according to the present disclosure, and  FIG. 19  is a bottom view of the light-emitting device according to the present disclosure. 
     A display device according to the present disclosure may include a lower substrate  310 , a lower electrode  320 , a flat layer  340 , a light-emitting device  350 , a second electrode  352 , a first electrode  356 , a black matrix  391 , a red color filter  380   a , a green color filter  380   b , a magnetic portion  321 , and a reaction portion  356   a . Hereinafter, these components will be described in detail. 
     A description of the lower substrate  310  will be replaced by the description of the lower substrate in  FIG. 3 , and a description of the lower electrode  320  will be replaced by the aforementioned description of the lower wiring. 
     The magnetic portion  321  is formed on the lower substrate  310  and generates a magnetic field, thereby forming an attractive force or repulsive force with a magnetic material. The magnetic portion  321  may be made of a thin film magnet. The thin film magnet may be made of a ferromagnetic material. For example, the thin film magnet may be made of an Sm—Co alloy. An area of the thin film magnet may correspond to 10 to 200% of an area of the semiconductor light-emitting device  350 . 
     Here, when the thin film magnet is made of a ferromagnetic material, the thin film magnet may be magnetized in a constant direction. The magnetization direction of the thin film magnet may be a direction perpendicular to the lower substrate  310 . This may allow the light-emitting device  350  to be aligned to a correct or proper position when transferring the light-emitting device  350  onto the lower substrate  310 . Since the magnetization direction greatly affects transfer accuracy, the thin film magnet should be made of the ferromagnetic material that is not affected by an external magnetic field. The Sm—Co alloy may be magnetized in a direction perpendicular to the lower substrate  310 , making it suitable to be used in the thin film magnet. 
     In one embodiment, based on the total weight of the thin film magnet, the thin film magnet may be made of an Sm—Co alloy composed of 34% of Sm and 66% of Co by weight, or an Sm—Co alloy composed of 23% of Sm and 77% of Co by weight. Here, an error range of the alloy composition is within 10%. 
     Meanwhile, a thickness of the thin film magnet may be 20 to 1000 nm. When the thickness of the thin film magnet is less than 20 nm, intensity of the magnetic field generated in the thin film magnet is insufficient to align the light-emitting device. In contrast, when the thickness of the thin film magnet exceeds 1000 nm, the resistivity (or specific resistance) of the circuit may be excessively increased due to the thin film magnet. 
     As illustrated in  FIG. 17 , the lower electrode  320  may include a plurality of layers, and the magnetic portion  321  and the reaction portion  322  may be any one of the plurality of layers constituting the lower electrode  320 . 
     Meanwhile, the reaction portion  356   a  that forms an attractive force with the magnetic portion  321  may be disposed at the light-emitting device  350 . As illustrated in  FIG. 18 , the reaction portion  356   a  may be disposed between a first conductive electrode  356   b  and a first conductive semiconductor layer  355 . 
     The reaction portion  356   a  may be made of a magnetic material. More specifically, the reaction portion  356   a  may be, preferably, a paramagnetic material. For transferring the light-emitting devices  350  onto the lower substrate  310 , a dispersion liquid of light-emitting device is applied onto the lower substrate  310 . Here, when the light-emitting device  350  is made of a ferromagnetic material, the light-emitting devices  350  may aggregate with each other. The reaction portion  356   a  may, preferably, react with a magnetic field generated in the magnetic portion  321 . 
     The reaction portion  356   a  may be made of a ferromagnetic material and a paramagnetic material. For example, the reaction portion  356   a  may be made of any one of Ni, Fe, Mo, and Co, or an Ni—Mo—Fe alloy or an Ni—Cr—Mo—Fe alloy. The Ni—Mo—Fe alloy and the Ni—Cr—Mo—Fe alloy have strong corrosion resistance to acid, thereby preventing the reaction portion  356   a  from being corroded by the acid used in a transfer process of the light-emitting devices  350 . 
     Meanwhile, a thickness of the reaction portion  356   a  may be 0.01 nm to 5 μm. When the thickness of the reaction portion  356   a  is less than 0.01 nm, an attractive force between the reaction portion  356   a  and the magnetic portion  321  may not be sufficient. In contrast, when the thickness of the reaction portion  356   a  exceeds 5 μm, the resistivity of the circuit may be excessively increased due to the reaction portion  356   a.    
     Meanwhile, each of the light-emitting devices  350  may include a first electrode electrically connected to the lower electrode  320  and having a plurality of layers, a first conductive semiconductor layer located on the first electrode, an active layer located on the first conductive semiconductor layer, and a second conductive semiconductor layer located on the active layer. The reaction portion  356   a  may be any one of the plurality of layers constituting the first electrode. 
     In detail, the first electrode may include a first metal layer in contact with the first conductive semiconductor layer and a second metal layer in contact with the lower electrode  320 . The reaction portion  356   a  may be disposed between the first metal layer and the second metal layer. As the reaction portion  356   a  made of a paramagnetic material increases the resistivity of the circuit, the first and second metal layers should have a lower resistivity than the reaction portion  356   a.    
     Alternatively, the reaction portion  356   a  may be made of a magnetically conductive material, so that the reaction portion  356   a  and the first conductive electrode  356   b  are formed as an integrated electrode, instead of being implemented as a separate layer formed on the first conductive electrode  356   b.    
     As illustrated in  FIG. 18 , areas of the reaction portion  356   a  and the first conductivity electrode  356   b  may be less (or smaller) than an area of the first conductivity semiconductor layer  355 . This is to improve transfer accuracy of the semiconductor light-emitting devices  350  that includes the second electrode layer  352 , the insulating layer  357 , the second conductive semiconductor layer  353  and the active layer  354 . 
     Meanwhile, the display device according to the present disclosure includes the flat layer  340  covering the wiring substrate  310  and having a plurality of holes  341 . The flat layer  340  may be made of a light transmissive material. 
     Each of the holes  341  formed in the flat layer  340  may be provided at a position corresponding to a region where the lower electrode  320  is formed. The hole  341  allows the lower electrode  320  to be exposed to the outside before the light-emitting device  350  is being transferred. 
     When the light-emitting device  350  is transferred while only a portion of the lower electrode  320  is exposed to the outside, the light-emitting device  350  is selectively transferred onto the lower electrode  320  that is exposed to the outside. As described above, the hole  341  serves to allow the light-emitting device  350  to be coupled to a specific position in the transfer process. 
     The hole  341  may be formed in various shapes. A shape of the light-emitting device  350  transferred on the lower electrode  320  may be changed (or determined) according to the shape of the hole  341 . In detail, when the hole  341  has a circular shape, a circular-shaped light-emitting device may be transferred onto the lower electrode  320 . Or, when the hole  341  has a rectangular shape, a rectangular-shaped light-emitting device may be transferred onto the lower electrode  320 . 
     Meanwhile, the display device according to the present disclosure may further include a metal bonding layer  360  that joins the light-emitting device  350  and the lower electrode  320  together. The metal bonding layer  360  is the same as described above. 
     When the display device is configured as described above, a time taken to transfer the light-emitting devices will be reduced. Hereinafter, a method of fabricating the display device according to the present disclosure will be described. 
       FIGS. 20A to 20C  are cross-sectional views illustrating a method of fabricating the display device according to the present disclosure. 
     As illustrated in  FIG. 20A , after forming the lower electrode  320  and the metal bonding layer  360  on the wiring substrate  310 , the flay layer  340  is formed to cover the wiring substrate  310 , the lower electrode  320 , and the metal bonding layer  360 . 
     Then, a plurality of holes  341  is formed at positions corresponding to the respective metal bonding layers  360  through hole processing. Accordingly, the metal bonding layer  360  is exposed to the outside. 
     Meanwhile, the lower electrode  320  includes the magnetic portion that generates an electric force or a magnetic force, as aforementioned. 
     Then, as shown in  FIG. 20B , a dispersion liquid of the light-emitting devices  350  is applied onto the wiring substrate  310  coated with the metal bonding layer  360 . When the dispersion liquid is applied, an attractive force is formed between the magnetic portion provided at the lower electrode  320  and the reaction portion provided at each of the light-emitting devices  350 . Accordingly, the light-emitting devices  350  are inserted into the hole  341 , and are then adhered to the metal bonding layer  360 , as illustrated in  FIG. 20C . Each of the light-emitting devices  350  is electrically connected to the lower electrode  320  through the metal bonding layer  360 . 
     When the light-emitting devices are transferred in this manner, it is not necessary to individually pick and place the light-emitting devices onto the electrode. 
     Meanwhile, as illustrated in  FIG. 21 , when shapes of holes  341   a ,  341   b  and  341   c  are formed differently, a light-emitting device having a specific shape may be attached or adhered to a specific position. In more detail, the plurality of holes may include a first hole  341   a  having a first shape and a second hole  341   b  having a different shape from the first shape, and a third hole  341   c  having a different shape from the first shape and the second shape. 
     A first light-emitting device  350   a  corresponding to the first shape may be only disposed on the first hole  341   a , a second light-emitting device  350   b  corresponding to the second shape may be only disposed on the second hole  341   b , and a third light-emitting device  350   c  corresponding to the third shape may be only disposed on the third hole  341   c . In case holes are formed into three types of shapes, a dispersion liquid mixed of the three different types of light-emitting devices is applied, thereby allowing transfer of R, G, and B light-emitting devices to be performed at once. 
     Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions and the like can be made without departing from the spirit of the disclosure, and these are, therefore, considered to be within the scope of the disclosure, as defined in the following claims.