Patent Publication Number: US-2022223575-A1

Title: Display device and manufacturing method therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national entry of International Application No. PCT/KR2020/001658, filed on Feb. 5, 2020, which claims under 35 U.S.C. §§ 119(a) and 365(b) priority to and benefits of Korean Patent Application No. 10-2019-0035948 filed on Mar. 28, 2019, in the Korean Intellectual Property Office (KIPO), the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to a display device and a method for manufacturing the same. 
     2. Description of Related Art 
     The importance of display devices is increasing with the development of multimedia. Accordingly, various types of display devices such as organic light-emitting display (OLED) devices and liquid crystal display (LCD) devices are being used. 
     A display panel such as an OLED panel or an LCD panel is a device included in a display device to display an image. Among such display panels, a light-emitting element may be provided as a light-emitting display panel, and examples of a light-emitting diode (LED) include an organic LED (OLED) using an organic material as a fluorescent material and an inorganic LED using an inorganic material as a fluorescent material. 
     An inorganic LED using an inorganic semiconductor as a fluorescent material has durability even in a high-temperature environment and has higher efficiency in blue light compared to the organic LED. In a manufacturing process pointed out as a limit of an existing inorganic LED element, a transfer method using a dielectrophoresis (DEP) method has been developed. Accordingly, research is being continuously conducted on the inorganic light-emitting diode having higher durability and efficiency than those of the organic light-emitting diode. 
     SUMMARY 
     Aspects of the disclosure provide a display device including a concave-convex pattern for emitting light emitted from a light emitting element upwards. 
     Aspects of the disclosure also provide a manufacturing process for a display device in which the device includes the concave-convex pattern such that a reflective member that reflects light emitted from a light emitting element is omitted, thereby reducing a manufacturing process of the device. 
     It should be noted that aspects of the disclosure are not limited thereto and other aspects, which are not mentioned herein, will be apparent to those of ordinary skill in the art from the following description. 
     According to an embodiment of the disclosure, a display device may comprise a first electrode, a second electrode spaced apart from the first electrode, a first insulating pattern disposed on the first electrode, at least partially overlapping the first electrode, and including a first side spaced apart from a first end of the first electrode, a second insulating pattern disposed on the second electrode and at least partially overlapping the second electrode and including a second side facing the first side spaced apart from an end of the second electrode facing the first end of the first electrode, at least one concave-convex pattern disposed on each of the first insulating pattern and the second insulating pattern, and at least one light emitting element disposed between the first insulating pattern and the second insulating pattern and including ends electrically connected to the first electrode and the second electrode, respectively. 
     A distance between the first insulating pattern and the second insulating pattern may be greater than a distance between the first electrode and the second electrode. 
     At least a portion of a top side of each of the first insulating pattern and the second insulating pattern may protrude upwards, and the at least one concave-convex patterns may be spaced apart from each other. 
     A concave or convex portion of the at least one concave-convex pattern may have at least one inclined outer side with respect to the top side of each of the first insulating pattern and the second insulating pattern. 
     At least a portion of the at least one concave-convex pattern may be located below a plane parallel to the first electrode and intersecting the ends of the at least one light emitting element. 
     The at least one concave-convex pattern may have a curved outer side. 
     The first insulating pattern may include a first hole pattern spaced apart from the first side and formed such that at least a portion of the top side of the first insulating pattern is recessed, and the second insulating pattern may include a second hole pattern spaced apart from the second side formed such that at least a portion of the top side of the second insulating pattern is recessed. 
     The at least one concave-convex pattern may be disposed between the first hole pattern and the first side, and disposed between the second hole pattern and the second side. 
     The display device may further comprise a fourth insulating pattern disposed between the first insulating pattern and the first electrode, a fifth insulating pattern placed between the second insulating pattern and the second electrode, and a sixth insulating pattern disposed between the fourth insulating pattern and the fifth insulating pattern, and partially overlapping each of the first end of the first electrode and the end of the second electrode. 
     The at least one light emitting element may be disposed on the sixth insulating pattern. 
     The display device may further comprise a first contact electrode disposed between the second insulating pattern and the sixth insulating pattern, and electrically contacting an end of the at least one light emitting element, and a second contact electrode disposed between the fifth insulating pattern and the sixth insulating pattern, and electrically contacting another end of the at least one light emitting element. 
     The display device may further comprise a third insulating pattern disposed between the first insulating pattern and the second insulating pattern, and disposed on at least a portion of a top side of the at least one light emitting element. 
     The display device may further comprise a bank spaced apart from a second end of the first electrode opposite to the first end of the first electrode. The first insulating pattern may be spaced apart from the bank, and the fourth insulating pattern may contact the bank. 
     A third side of the first insulating pattern opposite to the first side of the first insulating pattern may be located between the bank and the second end of the first electrode. 
     A distance between the first insulating pattern and the bank may be smaller than a distance between the first insulating pattern and the second insulating pattern. 
     The bank may be integral with the fourth insulating pattern. 
     According to an embodiment of the disclosure, a display device may comprise a first electrode extending in a first direction, and a second electrode extending in the first direction and spaced apart from the first electrode, at least one light emitting element disposed between the first electrode and the second electrode, a first insulating pattern extending in the first direction and partially overlapping the first electrode, a second insulating pattern extending in the first direction and spaced apart from the first insulating pattern and overlapping the second electrode, and at least one concave-convex pattern disposed on each of the first insulating pattern and the second insulating pattern. 
     A distance between the first insulating pattern and the second insulating pattern may be greater than a distance between the first electrode and the second electrode. 
     A first side portion of the first insulating pattern may be horizontally spaced inward from an end of the first electrode, and a second side portion of the first insulating pattern opposite to the first side portion horizontally may protrude outward beyond another end of the first electrode. 
     Two side portions of the second insulating pattern may be horizontally spaced inward from two ends of the second electrode, respectively. 
     The at least one concave-convex pattern may extend in a second direction and spaced apart from each other in a third direction different from the second direction. 
     The first insulating pattern may include a first hole pattern in which at least a portion of a top side of the first insulating pattern is recessed toward the first electrode. The second insulating pattern may include a second hole pattern in which at least a portion of a top side of the second insulating pattern may be recessed toward the second electrode, and each of the first hole pattern and the second hole pattern may extend in the first direction. 
     The at least one concave-convex pattern disposed on the first insulating pattern may be disposed between the first side portion and the first hole pattern, and the at least one concave-convex pattern disposed on the second insulating pattern may be disposed between each of side portions of the second insulating pattern and the second hole pattern. 
     According to an embodiment of the disclosure, a method for manufacturing a display device may comprise forming a first electrode and a second electrode on a substrate. The second electrode may be spaced apart from the first electrode, disposing at least one light emitting element between the first electrode and the second electrode, and forming at least one insulating pattern spaced apart from the at least one light emitting element and partially overlapping each of the first electrode and the second electrode. The at least one insulating pattern may have a concave-convex pattern in which at least a portion of a top side of the insulating pattern protrudes upwards. 
     The at least one insulating pattern may include a first insulating pattern at least partially overlapping the first electrode and, a second insulating pattern spaced apart from the first insulating pattern and at least partially overlapping the second electrode. Each of the first insulating pattern and the second insulating pattern may be spaced apart from the at least one light emitting element. 
     At least a portion of a top side of each of the first insulating pattern and the second insulating pattern protrudes upwards, and the concave-convex patterns may be spaced apart from each other. 
     The forming of the at least one insulating pattern may include forming an insulating material layer entirely overlapping the first electrode, the second electrode, and the at least one light emitting element, and exposing ends of the at least one light emitting element, and forming the first insulating pattern and the second insulating pattern having the concave-convex pattern formed thereon. 
     The forming of the at least one insulating pattern may be performed using a nano-imprinting process. 
     The method may further comprise forming a first contact electrode electrically contacting the first electrode and an end of the at least one light emitting element, and a second contact electrode electrically contacting the second electrode and another end of the at least one light emitting element. 
     The details of other embodiments are included in the detailed description and the accompanying drawings. 
     The display device according to one embodiment includes the insulating pattern onto which the light emitted from the light emitting element is incident and which includes the concave-convex pattern that receives the light and outputs upwards. As a result, in the display device free of a separate reflective electrode or reflective bank, the concave-convex pattern may output the light emitted from a side of the light emitting element in the upward direction. Thus, top emission efficiency thereof may be improved. 
     Further, the method for manufacturing the display device according to one embodiment may be free of a step of forming a reflective electrode or a reflective bank, and may perform the steps of forming the concave-convex pattern and forming the insulating pattern at the same time. Thus, the manufacturing process of the display device may be simplified. 
     The effects according to the embodiments are not limited by the contents exemplified above, and more various effects are included in this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An additional appreciation according to the embodiments of the disclosure will become more apparent by describing in detail the embodiments thereof with reference to the accompanying drawings, wherein: 
         FIG. 1  is a schematic plan view of a display device according to an embodiment. 
         FIG. 2  is a schematic cross-sectional view taken along lines IIa-IIa′, and IIc-IIc′ in  FIG. 1 . 
         FIG. 3  is a schematic diagram of a light emitting element according to an embodiment. 
         FIG. 4  is a schematic diagram illustrating a cross section of a portion of a display device according to an embodiment. 
         FIG. 5  is a schematic enlarged view of a portion A of  FIG. 4 . 
         FIG. 6  is a schematic plan view illustrating a top side of an insulating pattern according to an embodiment. 
         FIG. 7  is a schematic diagram illustrating a cross section of a sub-pixel according to an embodiment. 
         FIG. 8  is a flowchart illustrating a manufacturing process of the display device according to an embodiment. 
         FIG. 9  to  FIG. 16  are schematic cross-sectional views illustrating a manufacturing process of a display device according to an embodiment. 
         FIG. 17  to  FIG. 19  are schematic cross-sectional views illustrating a concave-convex pattern according to another embodiment. 
         FIG. 20  and  FIG. 21  are schematic plan views illustrating a concave-convex pattern according to another embodiment. 
         FIG. 22  is a schematic cross-sectional view of a display device according to another embodiment. 
         FIG. 23  and  FIG. 24  are schematic cross-sectional views of a display device according to another embodiment. 
         FIG. 25  to  FIG. 27  are schematic cross-sectional views illustrating some steps of a manufacturing process of the display device of  FIG. 24 . 
         FIG. 28  is a schematic cross-sectional view of a display device according to still another embodiment. 
         FIG. 29  and  FIG. 30  are schematic plan views illustrating a hole pattern formed in an insulating pattern according to still another embodiment. 
         FIG. 31  is a schematic cross-sectional view of a display device according to still yet another embodiment. 
         FIG. 32  is a schematic diagram of a light emitting element according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the disclosure are shown. This disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will convey the scope of the disclosure to those skilled in the art. 
     It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. The same reference numbers indicate the same components throughout the specification. 
     It will be understood that, although the terms “first,” “second,” and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For instance, a first element discussed below could be termed a second element without departing from the teachings of the disclosure. Similarly, the second element could also be termed the first element. 
     The terms “about” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” may mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value. 
     It will be understood that the terms “contact,” “connected to,” and “coupled to” may include a physical and/or electrical contact, connection or coupling. 
     The phrase “at least one of” is intended to include the meaning of “at least one selected from the group of ” for the purpose of its meaning and interpretation. For example, “at least one of A and B” may be understood to mean “A, B, or A and B.” 
     Unless otherwise defined or implied herein, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the disclosure, and should not be interpreted in an ideal or excessively formal sense unless clearly so defined herein. 
     Hereinafter, embodiments will be described with reference to the accompanying drawings. 
       FIG. 1  is a schematic plan view of a display device according to an embodiment. 
     Referring to  FIG. 1 , a display device  10  may include pixels PX. Each of the pixels PX may include at least one light emitting element  300  that emits light of a specific wavelength band to display a specific color. 
     Each of the pixels PX may include a first sub-pixel PX 1 , a second sub-pixel PX 2 , and a third sub-pixel PX 3 . The first sub-pixel PX 1  may emit light of a first color, the second sub-pixel PX 2  may emit light of a second color, and the third sub-pixel PX 3  may emit light of a third color. The first color may be red, the second color may be green, and the third color may be blue. However, the disclosure is not limited thereto. The sub-pixels PXn may emit light of the same color (where n is a natural number). Further,  FIG. 1  illustrates that a single pixel PX includes three sub-pixels PXn. However, the disclosure is not limited thereto. Each pixel PX may include a larger number of sub-pixels PXn. 
     As used herein, each of the terms “first,” “second,” etc. refers to each of components, and is used to simply distinguish components therebetween, and does not necessarily mean a corresponding component. That is, a component modified with each of the terms “first,” “second,” and the like is not necessarily limited to a specific structure or location. In some embodiments, another reference numeral may be assigned thereto. Accordingly, a reference numeral assigned to each component may be described based on the drawings and following descriptions. Further, a first element, component, region, layer, or section described below could be termed a second element, component, region, layer, or section, without departing from the spirit and scope of the disclosure. 
     Each sub-pixel PXn of the display device  10  may include a light-emitting area and a non-light-emitting area. The light-emitting area is defined as an area where a light emitting element  300  included in the display device  10  is disposed, and thus light of a specific wavelength band is output. The non-light emitting area may refer to an area other than the light-emitting area and may be defined as an area in which the light emitting element  300  is not disposed and thus light is not output. 
     The sub-pixel PXn of the display device  10  may include banks  400 , electrodes  210  and  220 , a light emitting element  300 , and at least one insulating layer  600  and  700 . 
     The electrodes  210  and  220  may be electrically connected to the light emitting element  300 . A predefined voltage may be applied to the electrodes  210  and  220  so that the light emitting element  300  emits light. Further, at least a portion of each of the electrodes  210  and  220  may be utilized to generate an electric field within the sub-pixel PXn to align the light emitting element  300 . 
     The electrodes  210  and  220  may include a first electrode  210  and a second electrode  220 . In an embodiment, the first electrode  210  may act as a separate pixel electrode for each sub-pixel PXn, and the second electrode  220  may act as a common electrode for the sub-pixels PXn. One of the first electrode  210  and the second electrode  220  may act as an anode of the light emitting element  300 , and the other thereof may act as a cathode of the light emitting element  300 . However, the disclosure is not limited thereto. One of the first electrode  210  and the second electrode  220  may act as a cathode of the light emitting element  300 , and the other thereof may act as an anode of the light emitting element  300 . 
     The first electrode  210  and the second electrode  220  may include electrode stems  210 S and  220 S extending in a first direction D 1 , respectively, and at least one electrode branch  210 B and at least one electrode branch  220 B respectively branching from the electrode stems  210 S and  220 S and extending in a second direction D 2  intersecting the first direction D 1 , respectively. 
     The first electrode  210  may include a first electrode stem  210 S extending in the first direction D 1 , and at least one first electrode branch  210 B branching from the first electrode stem  210 S and extending in the second direction D 2 . 
     The first electrode stem  210 S of a pixel may be discontinuous at a boundary between adjacent sub-pixels PXn. The first electrode stem  210 S may continuously extend in substantially the same straight line across neighboring sub-pixels (adjacent to each other in the first direction D 1 ) in the same row except for the discontinuity at the boundary between the adjacent sub-pixels PXn. Accordingly, different first electrode stems  210 S disposed in different sub-pixels PXn may apply different electrical signals to different first electrode branches  210 B, such that the different first electrode branches  210 B may be driven separately. 
     The first electrode branch  210 B may branch from at least a portion of the first electrode stem  210 S, may extend in the second direction D 2 , and may be terminated so as to be spaced apart from the second electrode stem  220 S opposite to the first electrode stem  210 S. 
     The second electrode  220  may include a second electrode stem  220 S extending in the first direction D 1  and spaced apart from and opposite to the first electrode stem  210 S, and a second electrode branch  220 B branching from the second electrode stem  220 S and extending in the second direction D 2 . The second electrode stem  220 S may extend across sub-pixels PXn adjacent to the pixel PX in the first direction D 1  without a discontinuity at a boundary between adjacent sub-pixels. Accordingly, the second electrode stem  220 S may continuously extend across adjacent pixels PX arranged in the first direction D 1  without a discontinuity at a boundary between adjacent pixels. 
     The second electrode branch  220 B may be spaced apart from and extend in a parallel manner to the first electrode branch  210 B and may be terminated so as to be spaced apart from the first electrode stem  210 S. For example, the second electrode branch  220 B may be disposed in the sub-pixel PXn and have an end connected to (and integral with) the second electrode stem  220 S, and the opposite end spaced apart from the first electrode stem  210 S. 
     Although  FIG. 1  shows that two second electrode branches  220 B are disposed in each sub-pixel PXn and a single first electrode branch  210 B is disposed between the two second electrode branches  220 B, the disclosure is not limited thereto. 
     The bank  400  may be disposed at a boundary between the sub-pixels PXn. As a result, the first electrode stem  210 S may be discontinuous at the bank  400 , and the second electrode stem  220 S may extend while passing by and under the bank  400 . The bank  400  may extend in the second direction D 2  and be disposed at the boundary between the sub-pixels PXn arranged in the first direction D 1 . However, the disclosure is not limited thereto. The bank  400  may extend in the first direction D 1  and may be disposed at the boundary between the sub-pixels PXn arranged in the second direction D 2 . 
     The light emitting elements  300  may be disposed between the first electrode branch  210 B and the second electrode branch  220 B. Each of at least some of the light emitting elements  300  may have an end electrically connected to the first electrode branch  210 B and another end electrically connected to the second electrode branch  220 B. 
     The light emitting elements  300  may be arranged and spaced from each other in the second direction D 2  and may be aligned with each other and may be substantially parallel to each other. A distance between the light emitting elements  300  is not particularly limited. In an embodiment, light emitting elements  300  may be spaced from each other by a constant distance. In an embodiment, light emitting elements  300  may be spaced from each other by irregular distances. In an embodiment, some of light emitting elements  300  may be spaced from each other by a constant distance, while the other of the plurality of light emitting elements  300  may be spaced from each other by irregular distances. 
     Insulating layers  600  and  700  are disposed in each sub-pixel PXn. The insulating layers  600  and  700  may include a first insulating layer  600  and a second insulating layer  700 . Although not shown in the drawing, the first insulating layer  600  may be disposed to cover (or overlap) an entire area of the sub-pixel PXn including the first electrode branch  210 B and the second electrode branch  220 B. The first insulating layer  600  may protect the electrodes  210  and  220  and insulate the electrodes  210  and  220  from each other so that the electrodes  210  and  220  do not directly contact each other. 
     The second insulating layer  700  may be disposed on the first insulating layer  600 , and at least a portion of the second insulating layer  700  may be disposed to partially overlap each of the electrode branches  210 B and  220 B. The second insulating layer  700  may include insulating patterns  710 ,  720 , and  730 , for example, first, second, and third insulating patterns  710 ,  720 ,  730 . A first insulating pattern  710  and a second insulating pattern  720  may be disposed to overlap the first electrode branch  210 B and the second electrode branch  220 B, respectively. The insulating patterns  710 ,  720 , and  730  may extend in a direction and may be spaced apart from each other in a direction different from the direction. 
     The first insulating pattern  710  may extend in the second direction D 2  and may be disposed on the first electrode branch  210 B. For example, a width of the first insulating pattern  710  may be smaller than a width of the first electrode branch  210 B. The first insulating pattern  710  may extend in a direction in which the first electrode branch  210 B extends and may be disposed between two contact electrodes  260  which will be described below. The first insulating pattern  710  may have both side portions contacting the two contact electrodes  260 , respectively. However, the disclosure is not limited thereto. The first insulating pattern  710  may have both opposing side portions spaced from or overlapping the two contact electrodes  260 , respectively. 
     The second insulating pattern  720  may extend in the second direction D 2  and may be disposed to partially overlap the second electrode branch  220 B. Unlike the first insulating pattern  710 , a portion of the second insulating pattern  720  may be disposed on the second electrode branch  220 B, and another portion thereof may be disposed on the first insulating layer  600 . A side of the second insulating pattern  720  may be disposed to contact, to be spaced from, or to overlap the contact electrode  260 , while another side thereof may be disposed between a side portion of the second electrode branch  220 B and the bank  400 . However, the disclosure is not limited thereto. 
     Although not shown in the drawing, a third insulating pattern  730  may be disposed between the first insulating pattern  710  and the second insulating pattern  720 . The third insulating pattern  730  may be disposed on the light emitting elements  300  and extend in a direction in which the light emitting elements  300  are arranged, for example, in the second direction D 2 . The third insulating pattern  730  may be disposed on the light emitting elements  300  and extend in the second direction D 2 . Thus, the third insulating pattern  730  may be disposed on the first insulating layer  600  in an area where the light emitting element  300  is not disposed. For example, the third insulating pattern  730  may be formed to substantially surround an outer side of the light emitting element  300 . 
     A shape of each of the insulating patterns  710 ,  720 , and  730  may be formed by placing a material forming (or constituting) the second insulating layer  700  to cover (or overlap)an entire area of each pixel PX or the sub-pixel PXn and partially patterning the placed material. However, the disclosure is not limited thereto. The insulating patterns  710 ,  720 , and  730  of the second insulating layer  700  may be formed by a single process. 
     In an embodiment, in the display device  10  according to one embodiment, at least one of the first insulating layer  600  and the second insulating layer  700  may include a concave-convex pattern  650 _ 3  or  750 , and thus may provide a light output path along which light emitted from the light emitting element  300  is output. The concave-convex pattern  650 _ 3  or  750  may be formed in a partial insulating pattern of the first or second insulating layer  600  or  700 . At least a portion of the light emitted from the light emitting element  300  may be incident on the first insulating layer  600  or the second insulating layer  700 , and exit therefrom toward a top of each sub-pixel PXn through the concave-convex pattern  650 _ 3  or  750 . Detailed descriptions of the insulating layers  600  and  700  and the insulating patterns  710 ,  720 , and  730  will be described below with reference to other drawings. 
     Each contact electrode  260  may be disposed on each of the first electrode branch  210 B and the second electrode branch  220 B. In this connection, a substantial portion of each contact electrode  260  may be disposed on the first insulating layer  600 , and at least a portion of each contact electrode  260  may contact each of the first electrode branch  210 B and the second electrode branch  220 B or may be electrically connected thereto. 
     Contact electrodes  260  may extend in the second direction D 2 , and may be arranged and be spaced apart from each other in the first direction D 1 . Each contact electrode  260  may contact at least one end of the light emitting element  300 , and each contact electrode  260  may be electrically connected to the first electrode  210  or the second electrode  220  and thus receive an electrical signal therefrom. Accordingly, each contact electrode  260  may transmit the electrical signal transmitted from the first electrode  210  or the second electrode  220  to the light emitting element  300 . 
     The contact electrodes  260  may include a first contact electrode  261  and a second contact electrode  262 . The first contact electrode  261  may be disposed on the first electrode branch  210 B and may contact an end of the light emitting element  300 . The second contact electrode  262  may be disposed on the second electrode branch  220 B and may contact another end of the light emitting element  300 . 
     The first electrode stem  210 S and the second electrode stem  220 S may be electrically connected to a circuit element layer of the display device  10  via contact holes, for example, a first electrode contact hole CNTD and a second electrode contact hole CNTS, respectively. The drawing shows that a second electrode contact hole CNTS is formed in the second electrode stem  220 S of the sub-pixels PXn. However, the disclosure is not limited thereto. In some embodiments, the second electrode contact hole CNTS may be formed in each sub-pixel PXn. 
     The display device  10  may further include the circuit element layer positioned below the electrodes  210  and  220  shown in  FIG. 1 . Hereinafter, a structure of the display device  10  will be described in detail with reference to  FIG. 2 . 
       FIG. 2  is a schematic cross-sectional view taken along lines IIa-IIa′, IIb-IIb′, and IIc-IIc′ in  FIG. 1 . 
       FIG. 2  illustrates a schematic cross-sectional view of the first sub-pixel PX 1 . However, this cross-sectional view may be equally applied to another pixel PX or sub-pixel PXn.  FIG. 2  illustrates a cross-section between an end and another end of a light emitting element  300 . 
     Referring to  FIGS. 1 and 2 , the display device  10  may include a substrate  110 , a buffer layer  115 , a light-blocking layer  180 , first and second transistors  120  and  140 , and the electrodes  210  and  220 , the light emitting element  300 , the first insulating layer  600 , and the second insulating layer  700  disposed above the first and second transistors  120  and  140 . 
     The substrate  110  may be embodied as an insulating substrate. The substrate  110  may be made of an insulating material such as glass, quartz, or polymer resin. Further, the substrate  110  may be a rigid substrate, or may be a flexible substrate which is capable of being bent, being folded, or is rollable. 
     The light-blocking layer  180  may be disposed on the substrate  110 . The light-blocking layer  180  may include a first light-blocking layer  181  and a second light-blocking layer  182 . The first light-blocking layer  181  may be electrically connected to a first drain electrode  123  of the first transistor  120  to be described below. The second light-blocking layer  182  may be electrically connected to a second drain electrode  143  of the second transistor  140  to be described below. 
     The first light-blocking layer  181  and the second light-blocking layer  182  may be disposed to overlap a first active material layer  126  of the first transistor  120  and a second active material layer  146  of the second transistor  140 , respectively. Each of the first and second light-blocking layers  181  and  182  may include a material that blocks light, and thus may prevent light from being incident on each of the first and second active material layers  126  and  146 . In an embodiment, each of the first and second light-blocking layers  181  and  182  may be made of an opaque metal material that blocks light transmission. 
     The buffer layer  115  may be disposed on the light-blocking layer  180  and the substrate  110 . The buffer layer  115  may be disposed to cover (or overlap)an entire area of the substrate  110 , including the light-blocking layer  180 . The buffer layer  115  may prevent diffusion of impurity ions, prevent invasion of moisture or external air, and perform a surface planarization function. Further, the buffer layer  115  may insulate the light-blocking layer  180  and the first and second active material layers  126  and  146  from each other. 
     A semiconductor layer may be disposed on the buffer layer  115 . The semiconductor layer may include the first active material layer  126  of the first transistor  120 , the second active material layer  146  of the second transistor  140 , and an auxiliary material layer  163 . The semiconductor layer may include polycrystalline silicon, monocrystalline silicon, oxide semiconductor, and the like. 
     A first gate insulating film  170  may be disposed on the semiconductor layer. The first gate insulating film  170  may be disposed to cover (or overlap)an entire area of the buffer layer  115 , including the semiconductor layer. The first gate insulating film  170  may function as a gate insulating film of each of the first and second transistors  120  and  140 . 
     A first conductive layer may be disposed on the first gate insulating film  170 . The first conductive layer may include a first gate electrode  121  disposed on the first gate insulating film  170  on the first active material layer  126  of the first transistor  120 , a second gate electrode  141  disposed on the first gate insulating film  170  on the second active material layer  146  of the second transistor  140 , and a power line  161  disposed on the first gate insulating film  170  on the auxiliary material layer  163 . 
     An interlayer insulating film  190  may be disposed on the first conductive layer. The interlayer insulating film  190  may perform an interlayer insulating function. Further, the interlayer insulating film  190  may include an organic insulating material and may perform a surface planarization function. 
     A second conductive layer may be disposed on the interlayer insulating film  190 . The second conductive layer may include the first drain electrode  123  and a first source electrode  124  of the first transistor  120 , the second drain electrode  143  and a second source electrode  144  of the second transistor  140 , and a power electrode  162  disposed on the power line  161 . 
     Each of the first drain electrode  123  and the first source electrode  124  may be electrically connected to the first active material layer  126  via a first contact hole extending through the interlayer insulating film  190  and the first gate insulating film  170 . Each of the second drain electrode  143  and the second source electrode  144  may be electrically connected to the second active material layer  146  via a second contact hole extending through the interlayer insulating film  190  and the first gate insulating film  170 . Further, the first drain electrode  123  and the second drain electrode  143  may be electrically connected to the first light-blocking layer  181  and the second light-blocking layer  182  via further contact holes, respectively. 
     A via layer  200  may be disposed on the second conductive layer. The via layer  200  may include an organic insulating material and perform a surface planarization function. 
     The bank  400  and the electrodes  210  and  220  are disposed on the via layer  200 . The bank  400  may be disposed at a boundary between the sub-pixels PXn such that the sub-pixels PXn are spaced apart from each other. 
     The bank  400  may define the boundary between the sub-pixels PXn. The bank  400  may extend in the first direction D 1  and the second direction D 2  to form a grid pattern and may be disposed at the boundary between the sub-pixels PXn. In case that an organic material or a solvent is sprayed using an inkjet printing method in manufacturing the display device  10 , the bank  400  may perform a function of preventing the organic material or the solvent from flowing between the sub-pixels PXn. As another example, in case that the display device  10  further includes another member, the another member may be disposed on the bank  400  so that the bank  400  may support the another member. The bank  400  may include polyimide (PI). 
     However, the disclosure is not limited thereto. The bank  400  may not necessarily be disposed on the via layer  200 . The bank  400  and the insulating layers  600  and  700  may be formed by a single process. In this case, the bank  400  may be integral with the insulating layers  600  and  700  and may have a partially protruding shape. 
     The electrodes  210  and  220  may be disposed on the via layer  200 . As described above, each of the electrodes  210  and  220  includes each of the electrode stems  210 S and  220 S and each of the electrode branches  210 B and  220 B. Line IIa-IIa′ in  FIG. 1  extends across the first electrode stem  210 S, line IIb-IIb′ in  FIG. 1  extends across the first electrode branch  210 B and the second electrode branch  220 B, and line IIc-IIc′ in  FIG. 1  extends across the second electrode stem  220 S. Each of the electrode stems  210 S and  220 S and each of the electrode branches  210 B and  220 B may form each of the first electrode  210  and the second electrode  220 . 
     At least a portion of the first electrode stem  210 S may overlap the bank  400 . As described above, the first electrode stem  210 S extends in the first direction D 1  and is discontinuous at the bank  400 . An end of the first electrode stem  210 S of the sub-pixel PXn may overlap the bank  400 , and the opposite end thereof may be spaced apart from the other bank  400 . An end of the first electrode stem  210 S overlapping the bank  400  may be electrically connected to the first drain electrode  123  via the first electrode contact hole CNTD that extends through the via layer  200  and exposes a portion of the first drain electrode  123  of the first transistor (or driving transistor)  120 . The first electrode stem  210 S may be electrically connected to the first drain electrode  123  of the driving transistor  120  and may receive a predefined electrical signal therefrom. 
     The first electrode branch  210 B and the second electrode branch  220 B may be spaced apart from each other. The first electrode branch  210 B and the second electrode branch  220 B are disposed in a central region of each sub-pixel PXn and are spaced apart from each other in the first direction D 1 . The light emitting elements  300  may be disposed in a space between the first electrode branch  210 B and the second electrode branch  220 B. 
     The second electrode stem  220 S may extend in a direction and further extend into the non-light emitting area where the light emitting elements  300  are not disposed. The second electrode stem  220 S may contact the power electrode  162  via a second electrode contact hole CNTS that extends through the via layer  200  and exposes a portion of the power electrode  162 . The second electrode stem  220 S may be electrically connected to the power electrode  162  and may receive a predefined electrical signal from the power electrode  162 . 
     Each of the electrodes  210  and  220  may include a transparent conductive material. In an embodiment, each of the electrodes  210  and  220  may include a material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), ITZO (Indium Tin-Zinc Oxide), etc. However, the disclosure is not limited thereto. In some embodiments, each of the electrodes  210  and  220  may include a conductive material having high reflectivity. For example, each of the electrodes  210  and  220  may include a metal such as silver (Ag), copper (Cu), aluminum (Al), etc. as the conductive material having high reflectivity. In this case, light incident on each of the electrodes  210  and  220  may be reflected therefrom and emitted toward a top of each sub-pixel PXn. 
     Further, each of the electrodes  210  and  220  may have a structure in which at least one transparent conductive material layer and at least one metal layer having high reflectivity are vertically stacked or may be composed of a single layer including the transparent conductive material and the metal having high reflectivity. In an embodiment, each of the electrodes  210  and  220  may have a stack structure of ITO/Ag/ITO/IZO, or may include an alloy including aluminum (Al), nickel (Ni), lanthanum (La), and the like. However, the disclosure is not limited thereto. 
     The first insulating layer  600  may be disposed to partially cover (or overlap)each of the first electrode  210  and the second electrode  220 . The first insulating layer  600  may be disposed to cover a substantial portion of a top side of each of the first electrode  210  and the second electrode  220 , but to expose a portion of each of the first electrode  210  and the second electrode  220 . The first insulating layer  600  may include a patterned portion  600 P exposing a portion of each of ends of the electrode branches  210 B and  220 B facing each other. Accordingly, the first insulating layer  600  may be discontinuous at the patterned portion  600 P. The contact electrode  260  may be disposed on the patterned portion  600 P such that the contact electrode  260  may contact the electrodes  210  and  220 . Further, the first insulating layer  600  may be partially disposed in an area between the second electrode branch  220 B and the bank  400 . A portion of the first insulating layer  600  disposed in an area between the first electrode branch  210 B and the second electrode branch  220 B may extend in the second direction D 2  and thus have an island shape or a linear shape. 
     The first insulating layer  600  may protect the first electrode  210  and the second electrode  220  and insulate the first electrode  210  and the second electrode  220  from each other. Further, the first insulating layer  600  may prevent the light emitting element  300  disposed on the first insulating layer  600  from directly contacting and damaged by other members. However, the shape and structure of the first insulating layer  600  are not limited thereto. In some embodiments, the first insulating layer  600  may have an insulating pattern having a concave-convex pattern formed thereon. For example, in case that the second insulating layer  700  is omitted, the first insulating layer  600  may include insulating patterns  610 _ 3 ,  620 _ 3 , and  630 _ 3  (shown in  FIG. 24 ), and a concave-convex pattern  650 _ 3  (shown in  FIG. 24 ) may be formed on the insulating pattern  610 _ 3 ,  620 _ 3 , or  630 _ 3 . In this case, the light emitted from the light emitting element  300  may be incident on the first insulating layer  600  and may be emitted toward the top of the sub-pixel PXn through the concave-convex pattern  650 _ 3  of the first insulating layer  600 . A detailed description thereof will be described below with reference to other drawings. 
     The light emitting element  300  may be disposed on the first insulating layer  600 . At least one light emitting element  300  may be disposed on a portion of the first insulating layer  600  disposed between the electrode branches  210 B and  220 B. Both opposing ends of the light emitting element  300  may be respectively aligned with both opposing ends of the underlying first insulating layer  600 . The light emitting element  300  may partially overlap the electrodes  210  and  220 . The light emitting element  300  may overlap each of ends of the first electrode branch  210 B and the second electrode branch  220 B facing toward each other and may be electrically connected to each of the electrodes  210  and  220  via the contact electrode  260 . 
     In an embodiment, the light emitting element  300  may include layers arranged in a direction parallel to the via layer  200 . The light emitting element  300  of the display device  10  according to an embodiment may include semiconductor layers of conductive types as above-described, and the active layer which may be sequentially arranged in a direction parallel to the via layer  200 . As shown in the drawing, the light emitting element  300  may include a first conductive type semiconductor  310 , an active layer  330 , a second conductive type semiconductor  320 , and a conductive electrode layer  370  which may be sequentially arranged in a direction parallel to the via layer  200 . However, the disclosure is not limited thereto. An order in which the layers of the light emitting element  300  are arranged may be reversed. In some embodiments, in case that the light emitting element  300  has a different structure from the above structure, the layers may be arranged in a direction perpendicular to the via layer  200 . 
     The second insulating layer  700  may be partially disposed on the first insulating layer  600  and the light emitting element  300 . The second insulating layer  700  may include the first insulating pattern  710 , the second insulating pattern  720 , and the third insulating pattern  730  as the insulating patterns. The first insulating pattern  710  and the second insulating pattern  730  may be disposed to overlap the first electrode branch  210 B and the second electrode branch  220 B, respectively, and the third insulating pattern  730  may be disposed on the light emitting element  300 . 
     The third insulating pattern  730  may protect the light emitting element  300  and perform a function of fixing the light emitting element  300  in the process of manufacturing the display device  10 . The third insulating pattern  730  may be disposed to partially surround an outer side of the light emitting element  300 . For example, a portion of a material of the third insulating pattern  730  may be disposed between a bottom side of the light emitting element  300  and the first insulating layer  600 . The third insulating pattern  730  may extend in the second direction D 2  and between the first electrode branch  210 B and the second electrode branch  220 B and thus may have an island-like or linear shape in a plan view. 
     The first insulating pattern  710  and the second insulating pattern  720  are disposed on the first insulating layer  600 . The first insulating pattern  710  and the second insulating pattern  720  may be spaced apart from the patterned portion  600 P of the first insulating layer  600 . For example, each of sides of the first insulating pattern  710  and the second insulating pattern  720  facing each other may be disposed on the first insulating layer  600  and may be horizontally spaced from the patterned portion  600 P. In an embodiment, the drawing shows that each of the sides of the first insulating pattern  710  and the second insulating pattern  720  facing each other is inclined at a predefined angle. However, the disclosure is not limited thereto. Each of the sides of the first insulating pattern  710  and the second insulating pattern  720  facing each other may extend in a perpendicular to a top side of the first insulating layer  600 . 
     In an embodiment, the first insulating pattern  710  and the second insulating pattern  720  may overlap the electrodes  210  and  220  or the electrode branches  210 B and  220 B, respectively. At least one side of each of the first insulating pattern  710  and the second insulating pattern  720  may vertically overlap each of the electrode branches  210 B and  220 B and may be horizontally spaced apart from a corresponding side of each of the electrode branches  210 B and  220 B. 
     The first insulating pattern  710  may overlap the first electrode branch  210 B. Both opposing sides of the first insulating pattern  710  may overlap the first electrode branch  210 B and may be horizontally spaced apart from both opposing sides of the first electrode branch  210 B, respectively. Although not shown in the drawing, the opposite side of the first insulating pattern  710  may overlap the first electrode branch  210 B and may be horizontally spaced from the opposite side of the first electrode branch  210 B. Accordingly, both opposing sides of the first insulating pattern  710  may be spaced apart from the light emitting elements  300 . As another example, both opposing sides of the first insulating pattern  710  may be aligned with both opposing sides of the first electrode branch  210 B, respectively. 
     The second insulating pattern  720  may overlap the second electrode branch  210 B. One side thereof may overlap the second electrode branch  210 B and be horizontally spaced apart from one side of the second electrode branch  220 B. Thus, one side of the second insulating pattern  720  may be spaced apart from the light emitting element  300 . However, the opposite side of the second insulating pattern  720  may be positioned between the opposite side of the second electrode branch  220 B and the bank  400 . For example, only a portion of the second insulating pattern  720  may overlap the second electrode branch  220 B, while an entirety of the first insulating pattern  710  may overlap the first electrode branch  210 B. 
     According to an embodiment, the second insulating layer  700  may include concave-convex patterns  750  respectively disposed on the first insulating pattern  710  and the second insulating pattern  720 . The concave-convex pattern  750  may have a shape in which a top side of each of the first insulating pattern  710  and the second insulating pattern  720  partially protrudes upwards. The concave-convex patterns  750  may be spaced apart from each other. The light emitted from the light emitting element  300  may travel without directionality. At least some of light beams may travel in a direction in which the light emitting element  300  extends, for example, in a direction parallel to the top side of the via layer  200 . As described above, the first insulating pattern  710  and the second insulating pattern  720  may be spaced apart from and face the light emitting element  300 . Thus, a portion of the light emitted from the light emitting element  300  may be incident on the first insulating pattern  710  and the second insulating pattern  720 , for example, the second insulating layer  700 . 
     In an embodiment, the second insulating layer  700  and the first insulating layer  600  may include materials having different refractive indexes. The light incident on the second insulating layer  700  may be reflected from an interface between a flat bottom side of the second insulating layer  700  and a flat top side of the first insulating layer  600 , and then may be emitted toward the concave-convex pattern  750  and then be output from the concave-convex pattern  750 . The concave-convex pattern  750  may be formed by patterning a top side of the second insulating layer  700  or performing a nano-imprinting method on the top side of the second insulating layer  700  during a process of forming the second insulating layer  700 . In an embodiment, a vertical dimension measured from the via layer  200  to a top side of the third insulating pattern  730  may be approximate to an average value of a vertical dimension measured from the via layer  200  to a top side of the first insulating pattern  710  or the second insulating pattern  720  and a vertical dimension measured from the via layer  200  to a top side of the concave-convex pattern  750 . For example, the vertical dimension measured from the via layer  200  to the top side of the third insulating pattern  730  may be larger than the vertical dimension measured from the via layer  200  to the top side of the first insulating pattern  710  or the second insulating pattern  720 , but may be smaller than the vertical dimension measured from the via layer  200  to the top side of the concave-convex pattern  750 . However, the disclosure is not limited thereto. 
     The drawing shows that the concave-convex pattern  750  has five convex portions on each of the first and second insulating patterns  710  and  720 . However, the disclosure is not limited thereto. The concave-convex pattern  750  may be formed on an entire area of the top side of each of the first and second insulating patterns  710  and  720 . In some embodiments, the concave-convex pattern  750  may be formed on a portion of the top side of each of the first and second insulating patterns  710  and  720  spaced apart from both opposing sides of each of the first and second insulating patterns  710  and  720 . Further, a shape of a convex portion or a concave portion of the concave-convex pattern  750  is not limited to a rectangular shape. The shape of the convex portion or the concave portion of the concave-convex pattern  750  may have various shapes. A detailed description thereof will be described below with reference to other drawings. 
     The contact electrode  260  may be disposed on each of the electrodes  210  and  220 , the first insulating layer  600 , and the second insulating layer  700 . The first contact electrode  261  and the second contact electrode  262  may be disposed on the third insulating pattern  730  of the second insulating layer  700  and be spaced apart from each other. Accordingly, the second insulating layer  700  may insulate the first contact electrode  261  and the second contact electrode  262  from each other. 
     In an embodiment, the first contact electrode  261  may contact a portion of the first electrode  210  exposed through the patterned portion  600 P of the first insulating layer  600 , and an end of the light emitting element  300 . The second contact electrode  262  may contact a portion of the second electrode  220  exposed through patterned portion  600 P, and the opposite end of the light emitting element  300 . The first and second contact electrodes  261  and  262  may respectively contact both opposing sides of the light emitting element  300 , for example, the first conductive type semiconductor  310 , the second conductive type semiconductor  320 , or the conductive electrode layer  370 . Both opposing sides of the first insulating layer  600  disposed between the first electrode branch  210 B and the second electrode branch  220 B and corresponding to the patterned portion  600 P may be respectively aligned with both opposing sides of the light emitting element  300 . Thus, the contact electrode  260  may smoothly contact both opposing sides of the light emitting element  300 . 
     Further, the first and second contact electrodes  261  and  262  may respectively contact the first and second insulating patterns  710  and  720  disposed on the first insulating layer  600 . The first and second contact electrodes  261  and  262  may be respectively disposed on both portions of the first insulating layer  600  adjacent to the patterned portion  600 P and facing each other and may extend toward the first insulating pattern  710  and the second insulating pattern  720 . The drawing shows that lower ends of the first and second contact electrodes  261  and  262  respectively extend to and contact the first and second insulating patterns  710  and  720 . However, the disclosure is not limited thereto. The first and second contact electrodes  261  and  262  may be respectively spaced apart from the first and second insulating patterns  710  and  720  or may respectively partially and vertically overlap the first and second insulating patterns  710  and  720 . 
     The contact electrode  260  may include a conductive material. An example of the conductive material may include ITO, IZO, ITZO, aluminum (Al), etc. However, the disclosure is not limited thereto. 
     A passivation layer  800  may be disposed on the bank  400 , the first insulating layer  600 , the second insulating layer  700 , and the contact electrode  260 . The passivation layer  800  may function to protect the members disposed on the via layer  200  from an external environment. 
     Each of the first insulating layer  600 , the second insulating layer  700 , and the passivation layer  800  as described above may include an inorganic insulating material or an organic insulating material. In an embodiment, each of the first insulating layer  600 , the second insulating layer  700 , and the passivation layer  800  may include an inorganic insulating material such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum oxide (A 1   2 O 3 ), aluminum nitride (AlN), and the like. As another example, each of the first insulating layer  600 , the second insulating layer  700 , and the passivation layer  800  may include an organic insulating material including acrylic resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene resin, polyphenylene sulfide resin, benzocyclobutene, cardo resin, siloxane resin, silsesquioxane resin, polymethyl methacrylate, polycarbonate, polymethyl methacrylate-polycarbonate synthetic resin, etc. However, the disclosure is not limited thereto. 
       FIG. 3  is a schematic diagram of a light emitting element according to an embodiment. 
     The light emitting element  300  may be a light emitting diode. Specifically, the light emitting element  300  may be embodied as an inorganic light-emissive diode made of an inorganic material and having a size of nano-meter to micro-meter. The light emitting elements  300  may be arranged between the two electrodes facing each other. In case that an electric field in a specific orientation is generated between the two electrodes and thus each of the two electrodes is polarized, the light emitting elements ED may be aligned in the same orientation therebetween. 
     The light emitting element  300  may have a shape extending in one direction (or first direction). The light emitting element  300  may have a shape such as a nanorod, a nanowire, or a nanotube. In an embodiment, the light emitting element  300  may have a cylindrical or shape. However, the shape of the light emitting element  300  is not limited thereto. The light emitting element  300  may have a variety of shapes. In another example, the light emitting element  300  may have a shape of a polygonal prism such as a cube, a cuboid, or a hexagonal prism. Semiconductors included in the light emitting element  300  to be described below may be sequentially arranged or stacked in said one direction (or first direction). 
     The light emitting element  300  may include a semiconductor crystal doped with impurities of any conductive type, for example, p-type or n-type impurities. The semiconductor crystal may receive an electrical signal applied from an external power source and emit light in a specific wavelength band in response to the electrical signal. 
     The light emitting element  300  according to an embodiment may emit light of a specific wavelength band. In an embodiment, light emitted from the active layer  330  may be blue light having a central wavelength band in a range of about 450 nm to about 495 nm. However, it should be understood that the central wavelength band of blue light is not limited to the above-described range and includes all wavelength ranges in which light may be recognized as blue light in the art. Further, the light emitted from the active layer  330  of the light emitting element  300  is not limited thereto. The light emitted from the active layer  330  of the light emitting element  300  may be green light having a central wavelength band in a range of about 495 nm to about 570 nm or be red light having a central wavelength band in a range of about 620 nm to about 750 nm. 
     In an embodiment, the light emitting element  300  according to an embodiment may include the first conductive type semiconductor  310 , the second conductive type semiconductor  320 , the active layer  330 , and an insulating film  380 . Further, the light emitting element  300  according to an embodiment may further include at least one conductive electrode layer  370 .  FIG. 3  illustrates that the light emitting element  300  further includes a conductive electrode layer  370 . However, the disclosure is not limited thereto. In some embodiments, the light emitting element  300  may include a larger number of conductive electrode layers  370  or may be free of the conductive electrode layer  370 . Following descriptions of the light emitting element  300  may be equally applied to a case where the number of the conductive electrode layers  370  varies or the light emitting element  300  further includes another component. 
     Referring to  FIG. 3 , the first conductive type semiconductor  310  may be, for example, an n-type semiconductor. The first conductive type semiconductor layer  310  may include a semiconductor material having a chemical formula of Al x Ga y In 1-x-y N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, the first conductive type semiconductor  310  may be made of at least one of AlGaInN, GaN, AlGaN, InGaN, AlN, and InN and may be doped with a n-type dopant. The first conductive type semiconductor  310  may be doped with an n-type dopant, for example, Si, Ge, Sn, or the like. In an embodiment, the first conductive type semiconductor  310  may be n-GaN doped with an n-type dopant of Si. A length of the first conductive type semiconductor  310  may be in a range of about 1.5 μm to about 5 μm. However, the disclosure is not limited thereto. 
     The second conductive type semiconductor  320  may be disposed on the active layer  330  which will be described below. The second conductive type semiconductor  320  may be, for example, a p-type semiconductor. In an embodiment, in case that the light emitting element  300  emits light of a blue or green wavelength band, the second conductive type semiconductor  320  may include a semiconductor material having a chemical formula of Al x Ga y In 1-x-y N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, the second conductive type semiconductor layer  320  may be made of at least one of AlGaInN, GaN, AlGaN, InGaN, AlN, and InN and may be doped with a p-type dopant. The second conductive type semiconductor layer  320  may be doped with a p-type dopant, for example, Mg, Zn, Ca, Se, Ba, or the like. In an embodiment, the second conductive type semiconductor  320  may be p-GaN doped with p-type Mg. A length of the second conductive type semiconductor  320  may be in a range of about 0.0 μm to about 0.25 μm. However, the disclosure is not limited thereto. 
     In an embodiment, the drawing shows that each of the first conductive type semiconductor  310  and the second conductive type semiconductor  320  is composed of a single layer. However, the disclosure is not limited thereto. In some embodiments, depending on the material of the active layer  330 , each of the first conductive type semiconductor  310  and the second conductive type semiconductor  320  may include a larger number of layers, for example, a clad layer or a TSBR (tensile strain barrier reducing) layer. 
     The active layer  330  may be disposed between the first conductive type semiconductor  310  and the second conductive type semiconductor  320 . The active layer  330  may include a material of a single or multiple quantum well structure. In case that the active layer  330  includes the material of the multiple quantum well structure, the active layer  330  may have a structure in which quantum layers and well layers are alternately stacked with each other. The active layer  330  may emit light via combinations of electrons and holes according to an electrical signal applied through the first conductive type semiconductor  310  and the second conductive type semiconductor  320 . In an embodiment, in case that the active layer  330  emits light of a blue wavelength band, the active layer  330  may include a material such as AlGaN and AlGaInN. In case that the active layer  330  has a structure in which quantum layers and well layers are alternately stacked with each other, the quantum layer may include a material such as AlGaN or AlGaInN, and the well layer may include a material such as GaN or AlInN. In an embodiment, in case that the active layer  330  includes AlGaInN as a material of the quantum layer, and AlInN as a material of the well layer. As described above, the active layer  330  may emit blue light having a central wavelength band in a range of about 450 nm to about 495 nm. 
     However, the disclosure is not limited thereto. The active layer  330  may have a structure in which first layers made of a semiconductor material having larger bandgap energy and second layers made of a semiconductor material having a smaller bandgap energy are alternately stacked with each other. The active layer  330  may include groups III to V semiconductor materials depending on a wavelength band of emitted light. The light emitted from the active layer  330  is not limited to light of a wavelength band corresponding to a blue color. In some embodiments, the light emitted from the active layer  330  may be light of a red or green wavelength band. A length of the active layer  330  may be in a range of about 0.05 μm to about 0.25 μm. However, the disclosure is not limited thereto. 
     In an embodiment, the light emitted from the active layer  330  may emit not only from an outer side of the light emitting element  300  in a length direction, but also from both opposing sides thereof. A direction of the light emitted from the active layer  330  is not limited to a direction. 
     The conductive electrode layer  370  may be an ohmic contact electrode. However, the disclosure is not limited thereto. The conductive electrode layer  370  may be a Schottky contact electrode. The conductive electrode layer  370  may include a conductive metal. For example, the conductive electrode layer  370  may include at least one of aluminum (Al), titanium (Ti), indium (In), gold (Au), silver, (Ag), ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), and ITZO (Indium Tin-Zinc Oxide). Further, the conductive electrode layer  370  may include a semiconductor material doped with n-type or p-type dopants. The conductive electrode layer  370  may include the same material or different materials. However, the disclosure is not limited thereto. 
     The insulating film  380  may be disposed to surround outer sides of the semiconductors as described above. In an embodiment, the insulating film  380  may be disposed to surround at least an outer side of the active layer  330  and may extend in a direction in which the light emitting element  300  extends. The insulating film  380  may perform a function of protecting the members. In an embodiment, the insulating film  380  may be formed to surround side sides of the members such that both opposing ends of the light emitting element  300  in a length direction of the light emitting element  300  may be exposed. 
     The drawing shows that the insulating film  380  extends in the longitudinal direction of the light emitting element  300  and covers (or overlaps) an area from the first conductive type semiconductor  310  to the conductive electrode layer  370 . However, the disclosure is not limited thereto. The insulating film  380  may cover an outer side of only one of the conductive type semiconductors and an outer side of the active layer  330  or may cover only a portion of an outer side of the conductive electrode layer  370  so that another portion of the outer side of the conductive electrode layer  370  may be exposed. 
     A thickness of insulating film  380  may be in a range of about 10 nm to about 1.0 μm. However, the disclosure is not limited thereto. The thickness of the insulating film  380  may be about 40 nm. 
     The insulating film  380  may include a material having insulating properties, for example, silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y ), aluminum nitride (AlN), aluminum oxide (Al 2 O 3 ), etc. Accordingly, the insulating film  380  may prevent an electrical short circuit that may otherwise occur in case that the active layer  330  directly contacts the electrode through which an electrical signal is transmitted to the light emitting element  300 . Further, the insulating film  380  protects the outer side of the light emitting element  300  including the active layer  330  such that a decrease in luminous efficiency may be prevented. 
     In some embodiments, the insulating film  380  may be surface-treated. The light emitting elements  300  may be sprayed onto the electrodes while being dispersed in ink during a manufacturing process of the display device  10  and may be aligned with each other. In this connection, in order to maintain a state in which the light emitting element  300  does not aggregate with other adjacent light emitting elements  300  in the ink, but the light emitting elements  300  are dispersed in the ink, the insulating film  380  may have a hydrophobic or hydrophilic surface. 
     In an embodiment, the light emitting element  300  may have a length h of about 1 μm to about 10 μm or about 2 μm to about 6 μm, preferably about 4 μm to about 5 μm. Further, a diameter of the light emitting element  300  may be in a range of about 300 nm to about 700 nm, and an aspect ratio of the light emitting element  300  may be in a range of about 1.2 to about 100. However, the disclosure is not limited thereto. The light emitting elements  300  included in the display device  10  may have different diameters because of differences between compositions of the active layers  330  thereof. The diameter of the light emitting element  300  may be about 500 nm. 
       FIG. 4  is a schematic diagram illustrating a cross section of a portion of a display device according to an embodiment.  FIG. 5  is a schematic enlarged view of portion A of  FIG. 4 .  FIG. 6  is a schematic plan view illustrating a top side of an insulating pattern according to an embodiment. 
     In  FIG. 4 , some members of the display device  10  are omitted or briefly illustrated in order to illustrate travel of the light emitted from the light emitting element  300  into the second insulating layer  700 .  FIG. 4  illustrates only the via layer  200 , the first electrode  210 , the second electrode  220 , the first insulating layer  600 , the light emitting element  300 , the second insulating layer  700 , and the contact electrode  260 , but a structure of the display device  10  is not limited thereto. The display device  10  may include the members as described above with reference to  FIG. 2 . Hereinafter, the insulating layers  600  and  700  of the display device  10  will be described in detail with reference to  FIG. 4  and other drawings. 
     Referring to  FIGS. 4 to 6 , at least a portion of the light emitted from the light emitting element  300  may be incident on the second insulating layer  700 . The light may be incident on one side (or first side)  710 S of the first insulating pattern  710  and one side (or first side)  720 S of the second insulating pattern  720 . The second insulating layer  700  may include an inorganic material or an organic insulating material having a predefined refractive-index. Light beams incident on the first insulating pattern  710  and the second insulating pattern  720  may be refracted on one side (or first sides)  710 S and  720 S, respectively, and travel in the first insulating pattern  710  and the second insulating pattern  720 , respectively. 
     Each of the first and second insulating patterns  710  and  720  may include a top side forming an interface with the passivation layer  800  disposed thereon, and a bottom side forming an interface with the underlying first insulating layer  600  as shown in  FIG. 2 . Light incident on the first and second insulating patterns  710  and  720  may be reflected or refracted on the top side and the bottom side of each of the insulating patterns  710  and  720  at which the interface is formed between the layers having different refractive indexes. The light beams reflected from the interface may not be output from the insulating patterns  710  and  720  such that the light efficiency of the display device  10  may decrease. 
     According to an embodiment, the second insulating layer  700  may include the concave-convex pattern  750  disposed on each of the insulating patterns  710  and  720  and thus provide an optical path through which light incident on the second insulating layer  700  is output. The light may be reflected and move in the second insulating layer  700  and then may be output therefrom through the concave-convex pattern  750  (EL in  FIG. 4 ). The concave-convex pattern  750  has a shape in which a portion of a top side of the second insulating layer  700  protrudes upwards. A protruding area may change an incident angle at which the light is incident in a totally reflected manner toward the top side of the second insulating layer  700 . Light incident on the concave-convex pattern  750  may be refracted at an interface between the concave-convex pattern  750  and an outside thereof and then may be output therefrom. The second insulating layer  700  may provide a travel path of the incident light and output the light through the concave-convex pattern  750 P, such that the light efficiency of the display device  10  may be improved. 
     The concave-convex pattern  750  is substantially integral with the second insulating layer  700 . The concave-convex pattern  750  may be formed by patterning the top side of the second insulating layer  700  or pressing the top side with a mold in a process of forming the second insulating layer  700 . However, the disclosure is not limited thereto. 
       FIG. 4  illustrates that a side of the concave-convex pattern  750  extends in a direction perpendicular to the top side of the second insulating layer  700  or the first insulating pattern  710 , and a top side of the concave-convex pattern  750  extends in a parallel manner to the top side of the first insulating pattern  710 . For example, a concave or convex portion of the concave-convex pattern  750  may have a shape of a quadrangle having a right angled corner. However, the disclosure is not limited thereto. A side of the concave or convex portion of the concave-convex pattern  750  may be inclined, or the concave or convex portion of the concave-convex pattern  750  may have a partially curved shape. 
     According to an embodiment, the concave-convex pattern  750  may at least a portion thereof extending in a direction. As shown in  FIG. 6 , the concave-convex pattern  750  may be formed on the top side of the second insulating layer  700 , and the concave-convex pattern  750  and the first and second insulating patterns  710  and  720  may be patterned to extend in substantially a same direction. In an embodiment, the concave-convex pattern  750  may be disposed on the first and second insulating patterns  710  and  720  and may extend in a parallel manner to a direction in which the insulating patterns  710  and  720  extend, for example, the second direction D 2 . However, the disclosure is not limited thereto. The concave-convex pattern  750  may extend in a direction different from a direction in which the insulating patterns  710  and  720  extend, or the concave-convex pattern  750  may be divided into repeated units which may be spaced from each other. 
     In an embodiment, each of the concave-convex patterns  750  may have a predefined vertical dimension or depth Gd or a predefined pitch Gp. The depth Gd and the pitch Gp of the concave-convex pattern  750  may vary based on a refractive index (N) of a material forming the second insulating layer  700  and a wavelength (λ) of light incident on the concave-convex pattern  750 . In an embodiment, each of the pitch Gp and the depth Gd of the concave-convex pattern  750  may be inversely proportional to the refractive index of the material of the second insulating layer  700  and may be proportional to the wavelength (λ) of the incident light. For example, in case that the refractive index of the second insulating layer  700  is larger or the wavelength (X) of the incident light is smaller, each of the pitch Gp and the depth Gd of the concave-convex pattern  750  may be smaller. Thus, the concave-convex patterns  750  may be dense on the second insulating layer  700 . In contrast, in case that the refractive index of the second insulating layer  700  is smaller or the wavelength (λ) of light is larger, each of the pitch Gp and the depth Gd of the concave-convex pattern  750  may be larger. 
       FIG. 7  is a schematic diagram illustrating a cross section of a sub-pixel according to an embodiment. 
     In  FIG. 7 , in order to illustrate a structure in which the first insulating pattern  710  and the second insulating pattern  720  of the second insulating layer  700  are arranged in each sub-pixel PXn, some members of the display device  10  are omitted or shown in a simpler manner.  FIG. 7  illustrates the via layer  200 , the first electrode  210 , the second electrode  220 , the bank  400 , the first insulating layer  600 , and the second insulating layer  700 . However, the structure of the display device  10  is not limited thereto. 
     Referring to  FIG. 7 , each sub-pixel PXn includes the bank  400 , the first electrode  210 , the second electrode  220 , the first insulating layer  600 , and the second insulating layer  700 . A sub-pixel PXn may include a first electrode branch  210 B and two second electrode branches  220 B and may include a first insulating pattern  710  and two second insulating pattern  720  overlapping the first electrode branch  210 B and the two second electrode branches  220 B, respectively. 
     The first electrode branch  210 B and the second electrode branch  220 B disposed in each sub-pixel PXn may have the same width. A width LE 1  of the first electrode branch  210 B is equal to a width LE 2  of the second electrode branch  220 B. In an embodiment, a width LI 1  of the first insulating pattern  710  may be smaller than a width LI 2  of the second insulating pattern  720 . As described above, the insulating patterns  710  and  720  may respectively overlap the electrode branches  210 B and  220 B, while at least one side of each of the insulating patterns  710  and  720  may overlap each of the electrode branches  210 B and  220 B but be horizontally spaced from a side of each of the electrode branches  210 B and  220 B. Accordingly, a side of each of the first and second insulating patterns  710  and  720  may be spaced apart from the light emitting element  300  disposed between the electrode branches  210 B and  220 B. 
     Unlike the second electrode branch  220 B, the first electrode branch  210 B may have both opposing sides horizontally spaced apart from both opposing sides of the second electrode branch  220 B, respectively. A side of the second electrode branch  220 B may face the first electrode branch  210 B, and the opposite side thereof may face the bank  400 . Accordingly, both opposing sides of the first insulating pattern  710  may overlap the first electrode branch  210 B but may be horizontally spaced from both opposing sides of the first electrode branch  210 B, respectively. A side of the second insulating pattern  720  may be disposed between the second electrode branch  220 B and the bank  400 . For example, the width LI 1  of the first insulating pattern  710  may be smaller than the width LI 2  of the second insulating pattern  720 . 
     According to an embodiment, a distance LIp between the first insulating pattern  710  and the second insulating pattern  720  may be greater than a distance LEp between the first electrode branch  210 B and the second electrode branch  220 B. Further, a distance LIg between the second insulating pattern  720  and the bank  400  may be smaller than the distance LIp between the first and second insulating patterns  710  and  720 . As described above, at least one side of each of the first and second insulating patterns  710  and  720  may overlap each of the electrode branches  210 B and  220 B but may be horizontally spaced from a side of each of the electrode branches  210 B and  220 B. Thus, distances therebetween may be different from each other. In an embodiment, each of the widths LI 1  and LI 2  of the first insulating pattern  710  and the second insulating pattern  720  may be in a range of about 10 μm to about 2 μm. However, the disclosure is not limited thereto. 
     The display device  10  according to an embodiment includes the second insulating layer  700  including the concave-convex pattern  750  as described above, which may provide a light travel path along which the light emitted by the light emitting element  300  is output toward a top of each pixel PX or sub-pixel PXn. Accordingly, the display device  10  may have improved top emission efficiency. Further, the device may be free of a separate bank structure or a reflective layer to reflect upward the light emitted from the light emitting element  300 . Thus, a manufacturing cost of the display device  10  may be reduced. 
     Hereinafter, a method for manufacturing the display device  10  according to an embodiment will be described. 
       FIG. 8  is a schematic flowchart illustrating a manufacturing process of a display device according to an embodiment.  FIGS. 9 to 16  are schematic cross-sectional views illustrating a manufacturing process of a display device according to an embodiment. 
     Referring to  FIG. 8 , the method for manufacturing the display device  10  according to an embodiment includes preparing a substrate on which the first electrode  210  and the second electrode  220  are disposed and placing the light emitting element  300  in a space between the first electrode  210  and the second electrode  220  (S 100 ), and forming at least one insulating pattern  710  and  720  that is spaced apart from the light emitting element  300 , partially overlaps the first electrode  210  and the second electrode  220 , and has the concave-convex pattern  750  formed on at least a portion of a top side thereof (S 200 ). 
     The display device  10  according to an embodiment may be manufactured by placing the light emitting element  300  on the substrate on which the first electrode  210  and the second electrode  220  are formed, and then forming the insulating patterns  710  and  720  having the concave-convex patterns  750 , respectively. Each of the insulating patterns  710  and  720  may be formed by forming a second insulating material layer  700 ′ so as to entirely overlap the first electrode  210  and the second electrode  220 , and by etching at least a portion of the second insulating material layer  700 ′ or performing a process of pressing the at least a portion of the second insulating material layer  700 ′ with a predefined mold. In an embodiment, the insulating patterns  710  and  720  may be formed by performing a patterning method or a nano-imprinting method such that the concave-convex pattern  750  may be disposed thereon while the insulating patterns  710  and  720  may be spaced apart from the light emitting element  300 . Hereinafter, the manufacturing process of the display device  10  will be described in detail with reference to other drawings. 
     First, referring to  FIG. 9 , the first electrode  210  and the second electrode  220  disposed on the via layer  200  are prepared, and a first insulating material layer  600 ′ disposed to cover (or overlap) an entire area of the first electrode  210  and the second electrode  220  is formed. The first electrode  210  and the second electrode  220  are spaced apart from each other. It may be understood that the first electrode  210  and the second electrode  220  in  FIG. 9  may act as substantially the first electrode branch  210 B and the second electrode branch  220 B, respectively. Descriptions of the structures thereof are the same as described above. 
     Although not shown in the drawing, the bank  400  as described above in  FIG. 2  may be disposed on the via layer  200 . In an embodiment, the bank  400  may be disposed directly on the via layer  200 . In some embodiments, the bank  400  may be formed simultaneously together with the first insulating material layer  600 ′. However, in following drawings including  FIG. 9 , the bank  400  will be omitted, and the formation of the insulating patterns  710  and  720  will be described in detail. 
     The first insulating material layer  600 ′ may be patterned in a step to be described below to form the first insulating layer  600 . The first insulating material layer  600 ′ may be disposed to cover (or overlap) an entire area of the top sides of the via layer  200  and the first electrode  210  and the second electrode  220 . In a subsequent process, the patterned portion  600 P exposing a portion of each of the first electrode  210  and the second electrode  220  is formed. In an embodiment, the first insulating material layer  600 ′ may include an inorganic insulating material. However, the disclosure is not limited thereto. The first insulating material layer  600 ′ may include an organic insulating material. 
     Next, referring to  FIG. 10 , at least one light emitting element  300  may be placed in an area between the first electrode  210  and the second electrode  220  and on the first insulating material layer  600 ′. In the step of placing the light emitting element  300 , ink containing the light emitting elements  300  may be sprayed, and then an electrical signal may be applied to each of the electrodes  210  and  220 . Thus, an electric field may be generated on the ejected or sprayed ink via the electrical signal applied to each of the electrodes  210  and  220 . Thus, the light emitting elements  300  may be subjected to a dielectrophoretic force resulting from the electric field. Thus, the light emitting element  300  subjected to the dielectrophoretic force may be oriented in a direction and may be arranged between the electrodes  210  and  220 . 
     Next, referring to  FIG. 11 , the second insulating material layer  700 ′ covering (or overlapping) an entire area of the top sides of the first insulating material layer  600 ′ and the light emitting elements  300  is formed. The second insulating material layer  700 ′ may be partially removed in a subsequent process to form the insulating patterns  710 ,  720 , and  730 . In an embodiment, the second insulating material layer  700 ′ may include an organic insulating material. In case that the second insulating material layer  700 ′ includes the organic insulating material, the second insulating material layer  700 ′ may be formed in an uncured state such that the concave-convex pattern  750  is formed in a subsequent process. However, the disclosure is not limited thereto. 
     Next, referring to  FIGS. 12 and 13 , a portion of the second insulating material layer  700 ′ is processed to form insulating patterns  710 ,  720 , and  730 . The insulating patterns may include the first insulating pattern  710  and the second insulating pattern  720  respectively including the concave-convex patterns  750 , and the third insulating pattern  730  disposed on the light emitting element  300  and exposing at least a portion of the light emitting element  300 . The descriptions of the structures and shapes of the first insulating pattern  710 , the second insulating pattern  720 , and the third insulating pattern  730  are the same as those as described above, and thus detailed descriptions thereof will be omitted. 
     According to an embodiment, in the step of forming the insulating patterns  710 ,  720 , and  730 , at least a portion of the light emitting element  300  may be exposed, and each of the concave-convex patterns  750  may be formed on at least a portion of each of the insulating patterns  710 ,  720 , and  730 . For example, a step of forming the concave-convex pattern  750  of the display device  10  and a step of exposing both opposing sides of the light emitting element  300  contacting the contact electrode  260  may be performed by a same process. In an embodiment, this process may be performed using a nano-imprinting method or a patterning method. Hereinafter, an example in which this process is carried out using the nano-imprinting method will be described. 
     As shown in  FIG. 12 , the top side of the second insulating material layer  700 ′ is pressed using a mold MOLD having a side having a partial protrusion, and then is irradiated with ultraviolet hv or is subjected to a heat-treatment H process. The mold MOLD has a first area having a concave-convex structure inverse to that of the concave-convex pattern  750  disposed on each of the first insulating pattern  710  and the second insulating pattern  720 ; and a second area having a structure which allows the opposing sides of the light emitting element  300  to be exposed and is inverse to a structure of the third insulating pattern  730  so as to form the third insulating pattern  730 . A concave-convex structure corresponding to the inverse concave-convex structure formed in the mold MOLD may be formed on the second insulating material layer  700 ′ including the uncured organic material. The concave-convex pattern  750  may be formed in an area of the second insulating material layer  700 ′ contacting the first area of the mold MOLD, while the third insulating pattern  730  may be formed in an area of the second insulating material layer  700 ′ contacting the second area of the mold, and the both opposing sides of the light emitting element  300  may be exposed in the area of the second insulating material layer  700 ′ contacting the second area thereof. 
     As shown in  FIG. 13 , after the mold MOLD has pressed the second insulating material layer  700 ′ and the ultraviolet hv irradiation and the heat-treatment H process have been carried out, the second insulating material layer  700 ′ may be sufficiently hardened. The mold MOLD is removed from the second insulating material layer  700 ′ to form the second insulating layer  700 . The second insulating layer  700  may include the first insulating pattern  710 , the second insulating pattern  720 , and the third insulating pattern  730 . Each of the both exposed opposing sides of the light emitting element  300  may be spaced apart from each of one sides (or first sides)  710 S and  720 S of the first insulating pattern  710  and the second insulating pattern  720 . A portion of the first insulating material layer  600 ′ may be exposed in the area between the sides  710 S and  720 S of the first insulating pattern  710 , and may be etched in a subsequent process such that the patterned portion  600 P may be formed. 
     In an embodiment, the process of forming the second insulating layer  700  is not limited thereto. In the process of forming the second insulating layer  700 , the concave-convex pattern  750  may be formed not using the mold MOLD but using a patterning process. 
       FIGS. 14A, 14B, and 14C  schematically illustrates a process of forming the second insulating layer  700 . The second insulating layer  700  includes the third insulating pattern  730  and the concave-convex pattern  750 , such that a top side thereof may not be flat, and a step (or height difference) may be formed on the top side thereof. The concave-convex pattern  750  having a fine size and a fine pitch may be formed by patterning the top side of the second insulating material layer  700 ′ at different pressing strengths in different areas thereof. In an embodiment, the process of forming the second insulating layer  700  may be performed by means of a patterning process using a halftone mask or a slit mask. First, as shown in  FIG. 14A , a portion of the second insulating material layer  700 ′ may be patterned to expose both opposing sides of the light emitting element  300 . The first insulating pattern  710 , the second insulating pattern  720 , and the third insulating pattern  730  may be formed. Then, each of the top sides of the first insulating pattern  710  and the second insulating pattern  720  may be partially patterned to form the concave-convex pattern  750 . In this connection, the concave-convex pattern  750  may be formed using a halftone mask MASK 1  as shown in  FIG. 14B , or using a slit mask MASK 2  as shown in  FIG. 14C . 
     Each of the top sides of the first insulating pattern  710  and the second insulating pattern  720  may be exposed to light beams by using the halftone mask MASK 1  or the slit mask MASK 2 . In this case, even in case that light is irradiated toward an entire area of the mask, only some of light beams corresponding to portions of the mask pass through the mask. Thus, the concave-convex pattern  750  having a fine size and a fine pitch may be formed on the top side of each of the first insulating pattern  710  and the second insulating pattern  720 . The method for manufacturing the display device  10  according to an embodiment may obtain the first insulating pattern  710  and the second insulating pattern  720  in which the concave-convex pattern  750  is formed, by designing a shape of the halftone mask MASK 1  or the slit mask MASK 2 . However, the disclosure is not limited thereto. 
     Next, as shown in  FIGS. 15 and 16 , a portion of the first insulating material layer  600 ′ exposed through a space between each of both opposing sides of the light emitting element  300  and each of the first insulating pattern  710  and the second insulating pattern  720  may be etched away to form the patterned portion  600 P. The first insulating material layer  600 ′ may be discontinuous at the patterned portion  600 P to form the first insulating layer  600 . 
     Next, although not shown in the drawing, the first contact electrode  261  and the second contact electrode  262  contacting the both exposed opposing sides of the light emitting element  300  are formed, and the passivation layer  800  covering (or overlapping)the first contact electrode  261  and the second contact electrode  262  is formed. In this way, the display device  10  may be manufactured. In forming the second insulating layer  700  including the insulating patterns  710 ,  720 , and  730  during the manufacturing of the display device  10  using the process as described above, both a process of exposing the both opposing sides of the light emitting element  300  and a process of forming the concave-convex pattern  750  on the first insulating pattern  710  and the second insulating pattern  720  may be simultaneously performed. 
     Further, forming the first insulating pattern  710  and the second insulating pattern  720  respectively including the concave-convex patterns  750  may allow omitting a reflective electrode that reflects the light emitted from the light emitting element  300 , such that the number of steps for manufacturing the display device  10  may be reduced, thereby improving manufacturing efficiency. 
     In an embodiment, as described above, a shape of the concave-convex pattern  750  of the display device  10  is not limited to a shape shown in  FIG. 4 . In some embodiments, the concave or convex portion of the concave-convex pattern  750  may have an inclined side, or have a curved shape. 
       FIGS. 17 to 19  are schematic cross-sectional views illustrating a concave-convex pattern according to an embodiment.  FIGS. 17 to 19  illustrates enlarged cross sections of a portion corresponding to portion A of  FIG. 4  according to an embodiment. 
     Referring to  FIGS. 17 to 19 , a concave or convex portion of the concave-convex pattern  750  according to an embodiment may have an inclined side extending from a top side of the second insulating layer  700  or the first insulating pattern  710 . The concave or convex portion of the concave-convex pattern  750  in  FIG. 17  has both opposing sides having a predefined inclination angle Θq. A concave or convex portion of the concave-convex pattern  750  of  FIG. 18  may have an inclined side and the opposite side which may extend in a perpendicular manner to the top side of the first insulating pattern  710 . A concave or convex portion of the concave-convex pattern  750  in  FIG. 19  may have a curved shape protruding upwards. Depending on the shape of the concave or convex portion of the concave-convex pattern  750 , light incident on the first insulating pattern  710  may be incident on the concave-convex pattern  750  at various angles of incidence. A percentage of an amount of light which is not reflected from the concave-convex pattern  750  but is output through the concave-convex pattern  750  to the outside may increase. 
     Further, in case that as shown in  FIGS. 18 and 19 , the concave or convex portion of the concave-convex pattern  750  has a prism shape or a micro lens shape having a curved outer side, the concave-convex pattern  750  may scatter incident light thereon, thereby further increasing the top emission efficiency of the device. 
       FIGS. 20 and 21  are schematic plan views illustrating a concave-convex pattern according to an embodiment. 
     First, referring to  FIG. 20 , the concave-convex pattern  750  may be disposed on the first insulating pattern  710  and the second insulating pattern  720  and extend in a direction. The direction in which the concave-convex pattern  750  extends is not particularly limited. In an embodiment, the concave-convex pattern  750  may extend in a direction different from the second direction D 2  in which the first insulating pattern  710  extends. In an embodiment, as shown in  FIG. 20 , the concave-convex pattern  750  may extend in an oblique direction with respect to the second direction D 2 . 
     Further, referring to  FIG. 21 , the concave-convex pattern  750  does not extend in a direction and has repeating units. Concave-convex patterns  750  may be arranged and be spaced apart from each other. For example, the concave-convex patterns  750  may be arranged in a single grid pattern on the first insulating pattern  710  or the second insulating pattern  720 . 
     Such various structures of the concave-convex pattern  750  may be formed using a mold MOLD having a convex or concave structure inverse to a convex or concave structure of the concave-convex pattern  750  during the manufacturing process of the display device  10 . In case that the inverse convex or concave structure of the mold MOLD extends in a direction, the concave-convex pattern  750  formed on the first insulating pattern  710  and the second insulating pattern  720  may extend in a direction. In case that the inverse convex or concave structure of the mold MOLD has a grid pattern, the concave-convex pattern  750  formed on the first insulating pattern  710  and the second insulating pattern  720  may have a grid pattern. However, the disclosure is not limited thereto. 
     Hereinafter, other embodiments of the display device  10  will be described. 
       FIG. 22  is a schematic cross-sectional view of a display device according to an embodiment. 
     Referring to  FIG. 22 , according to an embodiment, a display device  10 _ 1  may include electrodes  210 _ 1  and  220 _ 1  including a material having high reflectivity. For example, each of the electrodes  210 _ 1  and  220 _ 1  of the display device  10 _ 1  may act as a reflective electrode that reflects incident light. The display device  10   1  of  FIG. 22  is the same as the display device  10  of  FIG. 2  except that a material forming the electrodes  210 _ 1  and  220 _ 1  is different from that in the display device  10  of  FIG. 2 . Thus, repetitive descriptions thereof will be omitted. 
     Light emitted from the light emitting element  300  may be reflected or refracted at an interface between each of the first insulating pattern  710  and the second insulating pattern  720  and another layer and then may travel. At least a portion of the light may not be reflected but be refracted at the interface between each of the first insulating pattern  710  and the second insulating pattern  720  and the first insulating layer  600  and then may be incident on each of the electrodes  210 _ 1  and  220 _ 1 . 
     The display device  10   1  according to an embodiment may include the electrodes  210 _ 1  and  220 _ 1  made of a material having high reflectivity, such that light may be reflected from the electrodes  210 _ 1  and  220 _ 1 . In an embodiment, each of the electrodes  210 _ 1  and  220 _ 1  may be made of the material with high reflectivity including a metal such as silver (Ag), copper (Cu), aluminum (Al), etc., or may have a stack structure of ITO/silver(Ag)/ITO/IZO, or may be made of an alloy including aluminum (Al), nickel (Ni), lanthanum (La), and the like. However, the disclosure is not limited thereto. The display device  10 _ 1  may include the electrodes  210 _ 1  and  220 _ 1  made of a material having high reflectivity, and thus may have a reduced loss of light for each pixel PX or each sub-pixel PXn and thus may have improved top emission efficiency. 
       FIGS. 23 and 24  are schematic cross-sectional views of a display device according to an embodiment. 
     Referring to  FIG. 23 , in a display device  10 _ 2  according to an embodiment, a first insulating layer  600 _ 2  and a bank  400 _ 2  may be formed by a same process. For example, the first insulating layer  600 _ 2  and the bank  400 _ 2  may be integrated into a layer. The display device  10 _ 2  in  FIG. 23  is the same as the display device  10  in  FIG. 2  except that the first insulating layer  600 _ 2  and the bank  400 _ 2  are integrated into a single layer. Thus, repetitive descriptions thereof will be omitted. 
     The first insulating layer  600 _ 2  may be formed by patterning an inorganic material or an organic insulating material, or may be formed by using a nano-imprinting method. In an embodiment, in case that the first insulating layer  600 _ 2  is formed using the nano-imprinting method, the first insulating layer  600 _ 2  having different steps may be formed over the substrate on which the electrodes  210  and  220  are formed. However, the disclosure is not limited thereto. The first insulating layer  600 _ 2  having different steps (or height differences) may be formed using a slit mask or a halftone mask, and the bank  400 _ 2  may be formed at the same time. As a result, the process of forming a separate bank  400  is omitted, so that there is an advantage in the manufacturing process of the display device  10 _ 2 . 
     Referring to  FIG. 24 , in a display device  10 _ 3  according to an embodiment, the second insulating layer  700  may be omitted, and a first insulating layer  600 _ 3  may include insulating patterns  610 _ 3 ,  620 _ 3 , and  630 _ 3 . Unlike the first insulating layer  600  in  FIG. 2 , the first insulating layer  600 _ 3  in  FIG. 24  may have the insulating patterns  610 _ 3 ,  620 _ 3 , and  630 _ 3  having different steps. As described above, the first insulating layer  600 _ 3  may be formed using a nano-imprinting method. According to an embodiment, in a process of forming the first insulating layer  600 _ 3 , some of insulating patterns  610 _ 3 ,  620 _ 3 , and  630 _ 3  may have a thickness smaller than that of the other of the insulating patterns  610 _ 3 ,  620 _ 3 , and  630 _ 3 . 
     In an embodiment, fourth and fifth insulating patterns  610 _ 3  and  620 _ 3  may be spaced apart from a sixth insulating pattern  630 _ 3  via the patterned portion  600 P_ 3 . The contact electrodes  261  and  262  may be disposed on the patterned portion  600 P_ 3 , and the contact electrodes  261  and  262  may contact the electrode branches  210 B and  220 B, respectively. In the display device  10 _ 3  of  FIG. 22 , the second insulating layer  700  is omitted, such that portions of the first and second contact electrodes  261  and  262  on a top face of the light emitting element  300  instead of a top face of the third insulating pattern  730  are spaced apart from each other. 
     Further, in the display device  10 _ 3  in  FIG. 24 , the first insulating layer  600 _ 3  and a bank  400 _ 3  may be formed by a same process. Thus, the bank  400 _ 3  may be integral with a partial insulating pattern of the first insulating layer  600 _ 3 . Descriptions of the bank  400 _ 3  integral with the first insulating layer  600 _ 3  are the same as described above with reference to  FIG. 23 . 
     The first insulating layer  600 _ 3  may include the fourth insulating pattern  610 _ 3 , the fifth insulating pattern  620 _ 3 , and the sixth insulating pattern  630 _ 3 . The fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  may at least partially overlap the electrode branches  210 B and  220 B, respectively. The sixth insulating pattern  630 _ 3  may be disposed between the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  and may be disposed to cover (or overlap) an end of each of the electrode branches  210 B and  220 B. In an embodiment, the sixth insulating pattern  630 _ 3  may have a thickness measured in a direction smaller than that of each of the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3 . For example, the insulating patterns  610 _ 3 ,  620 _ 3 , and  630 _ 3  may have different vertical dimensions from the via layer  200  such that steps are formed on top sides thereof. The light emitting element  300  may be disposed on the sixth insulating pattern  630 _ 3 , which has the vertical dimension smaller than that of each of the other insulating patterns  610 _ 3  and  620 _ 3 . The sixth insulating pattern  630 _ 3  of  FIG. 24  may correspond to a portion of the first insulating layer  600  of  FIG. 2  disposed between the electrode branches  210 B and  220 B and spaced apart from other portions of the first insulating layer  600  via the patterned portion  600 P. 
     In an embodiment, each of the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  may include a concave-convex pattern  650 _ 3  in which at least a portion of a top side thereof protrudes upwards. The fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  in  FIG. 24  may respectively correspond to the first insulating pattern  710  and the second insulating pattern  720  in  FIG. 2 . 
     In an embodiment, as in the first insulating pattern  710  of  FIG. 2 , the fourth insulating pattern  610 _ 3  may be formed such that both opposing sides thereof are respectively and horizontally spaced apart from both opposing side portions of the first electrode branch  210 B while overlapping the first electrode branch  210 B. A width measured in a direction of the fourth insulating pattern  610 _ 3  may be smaller than a width of the first electrode branch  210 B. The fourth insulating pattern  610 _ 3  may be spaced apart from the sixth insulating pattern  630 _ 3  via the patterned portion  600 P_ 3 , and at least one side of the fourth insulating pattern  610 _ 3  may be spaced apart from the light emitting element  300 . 
     As in the second insulating pattern  720  of  FIG. 2 , the fifth insulating pattern  620 _ 3  may be formed such that a side thereof is horizontally spaced apart from a side of the second electrode branch  210 B while vertically overlapping the second electrode branch  210 B. However, the opposite side of the fifth insulating pattern  620 _ 3  may be integral with the bank  400 _ 3 . Unlike the second insulating pattern  720  in  FIG. 2 , the fifth insulating pattern  620 _ 3  may not be spaced apart from the bank  400 _ 3 . For example, the fifth insulating pattern  620 _ 3  and the bank  400 _ 3  may be integrated into a single layer. 
     Each of the concave-convex patterns  650 _ 3  may be formed on at least a portion of each of top sides of the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3 . The concave-convex pattern  650 _ 3  may be formed in an area thereof overlapping each of the electrode branches  210 B and  220 B. However, the disclosure is not limited thereto. The concave-convex pattern  650 _ 3  formed on the fifth insulating pattern  620 _ 3  may extend to the bank  400 _ 3 . Unlike the display device  10  in  FIG. 2 , the display device  10 _ 3  of  FIG. 24  is configured such that a part of an insulating pattern of the first insulating layer  600 _ 3  may include the concave-convex pattern  650 _ 3  positioned above the light emitting element  300  in a cross-sectional view such that the light emitted from the light emitting element  300  is incident on the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3 . 
     The display device  10 _ 3  in  FIG. 24  may include the concave-convex pattern  650 _ 3  that provides a travel path of light emitted from the light emitting element  300 , and may be free of the second insulating layer  700 , and thus has an advantage in the manufacturing process of the display device  10 _ 3 . 
       FIGS. 25 to 27  are schematic cross-sectional views illustrating some steps of the manufacturing process of the display device of  FIG. 24 . 
     In the display device  10 _ 3  of  FIG. 24 , the second insulating layer  700  is omitted, and the first insulating layer  600 _ 3  includes the insulating patterns  610 _ 3 ,  620 _ 3 , and  630 _ 3 . The manufacturing process of the display device  10 _ 3  may be free of forming the second insulating layer  700  and may include forming the first insulating layer  600 _ 3  on the electrodes  210  and  220  and placing the light emitting element  300 . 
     Referring to  FIG. 25 , the first electrode  210  and the second electrode  220  are formed on the via layer  200 , and a first insulating material layer  600 ′_ 3  covering (or overlapping) an entire area thereof is formed. The first insulating material layer  600 ′_ 3  in  FIG. 25  may have a relatively larger thickness, unlike the first insulating material layer  600 ′ in  FIG. 9 . A portion of the first insulating material layer  600 ′_ 3  in  FIG. 25  may be patterned by a subsequent process to form a space in which the light emitting element  300  is disposed. 
     Next, referring to  FIG. 26 , at least a portion of the first insulating material layer  600 ′_ 3  is patterned such that the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  respectively including the concave-convex patterns  650 _ 3  are formed. The first insulating material layer  600 ′_ 3  may have a shape in which a portion thereof is recessed so that the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  are spaced apart from each other and face each other. The fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  respectively include one sides (or first sides)  610 S_ 3  and  620 S_ 3  that are spaced apart from each other and face each other. Each of one side  610 S_ 3  of the fourth insulating pattern  610 _ 3  and one side face  620 S_ 3  of the fifth insulating pattern  620 _ 3  may be formed to be inclined with respect to each top side on which each concave-convex pattern  650 _ 3  is formed. A spaced area between the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  overlaps a spaced area between the first electrode  210  and the second electrode  220 . The light emitting element  300  may be placed in the spaced area between the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  by a subsequent process. 
     Next, referring to  FIG. 27 , at least one light emitting element  300  is placed in the spaced area between the fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3 . A patterned portion  600 P_ 3  partially exposing the first electrode  210  and the second electrode  220  is formed by etching at least a portion of the first insulating material layer  600 ′_ 3 . The patterned portions  600 P_ 3  may be respectively formed along and on both opposing sides of the light emitting element  300  disposed on the first insulating material layer  600 ′_ 3 . The sixth insulating pattern  630 _ 3  may be formed between the patterned portions  600 P_ 3 . The fourth insulating pattern  610 _ 3  and the fifth insulating pattern  620 _ 3  may be spaced from each other via the patterned portion  600 P_ 3  and may be spaced from the sixth insulating pattern  630 _ 3  via the patterned portion  600 P_ 3 . 
     Next, although not shown in the drawings, the first contact electrode  261  and the second contact electrode  262  disposed in the patterned portion  600 P_ 3  are formed, and then the passivation layer  800  covering (or overlapping) the first contact electrode  261  and the second contact electrode  262  is formed. Thus, the display device  10 _ 3  of  FIG. 24  may be manufactured. 
       FIG. 28  is a schematic cross-sectional view of a display device according to an embodiment.  FIGS. 29 and 30  are schematic plan views illustrating hole patterns formed in an insulating pattern according to an embodiment. 
     Referring to  FIG. 28 , a display device  10 _ 4  according to an embodiment may include each of hole patterns  710   h  and  720   h  in which at least a portion of each of first and second insulating patterns  710 _ 4  and  720 _ 4  is recessed. The display device  10 _ 4  in  FIG. 28  may be different from the display device  10  in  FIG. 4  at least in that each of the first and second insulating patterns  710 _ 4  and  720 _ 4  further includes each of the hole patterns  710   h  and  720   h . Hereinafter, repetitive descriptions thereof will be omitted, and descriptions will be made focusing on differences. 
     According to an embodiment, the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4  on which the light emitted from the light emitting element  300  is incident may include at least one hole pattern  710   h  and at least one hole pattern  720   h , respectively. The light incident on the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4  may be reflected at an interface between each of the insulating patterns and another layer and then be output through a concave-convex pattern  750 _ 4 . However, in some embodiments, some of light beams that travel in the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4  may not be output through the concave-convex pattern  750 _ 4  but may be continuously reflected in the insulating patterns and travel therein. A third insulating pattern  730 _ 4  may be disposed on the light emitting element  300 . 
     Although not shown in the drawing, in case that the bank  400  is integral with the second insulating layer  700 , a portion of the light incident onto the second insulating pattern  720 _ 4  may travel to a position where the bank  400  is located, and may not be output to the outside. The first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4  according to an embodiment may include at least one hole pattern  710   h  and at least one hole pattern  720   h  respectively to change a path of light traveling in the insulating pattern in order to minimize loss of the incident light. The hole patterns  710   h  and  720   h  may include a first hole pattern  710   h  formed in the first insulating pattern  710 _ 4  and a second hole pattern  720   h  formed in the second insulating pattern  720 _ 4 . As shown in the figure, a portion of the light traveling in each of the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4  may be reflected from each of the hole patterns  710   h  and  720   h  and then may be output through the concave-convex pattern  750 _ 4 . 
     Each of the hole patterns  710   h  and  720   h  may be formed by etching at least a portion of each of top sides of the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4 . Each of depths of the hole patterns  710   h  and  720   h  is not particularly limited. Each of depths of the hole patterns  710   h  and  720   h  may be smaller than a thickness of each of the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4  so that the first insulating layer  600  is not exposed. 
     Each of both opposing sides of the first insulating pattern  710 _ 4  may face the light emitting element  300  while being spaced apart from the light emitting element  300 . The first hole pattern  710   h  may be located at a center of the first insulating pattern  710 _ 4 . In contrast, a side of the second insulating pattern  720 _ 4  faces the light emitting element  300 , while the opposite side thereof faces the bank  400 . Thus, the second hole pattern  720   h  may be disposed adjacent to the bank  400  and in the second insulating pattern  720 _ 4 . However, the disclosure is not limited thereto. Hole patterns  710   h  and hole patterns  720   h  may be respectively formed in the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4 , respectively, and may be spaced from each other. 
     Referring to  FIG. 29 , in an embodiment, each of the hole patterns  710   h  and  720   h  may have a shape extending in a direction and along each of the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4 . Similar to the concave-convex pattern  750 , each of the hole patterns  710   h  and  720   h  may extend in a direction (or second direction D 2 ) in which each of the first insulating pattern  710 _ 4  and the second insulating pattern  720 _ 4  extends. 
     However, the disclosure is not limited thereto. A larger number of hole patterns  710   h  and a larger number of hole patterns  720   h  may be formed to define a single unit hole pattern  710   h  and a single unit hole pattern 720   h , respectively. Referring to  FIG. 30 , the hole patterns  710   h  may be formed in the first insulating pattern  710 _ 4  and may be spaced from each other to form a grid pattern. The hole patterns  720   h  may be formed in the second insulating pattern  720 _ 4  and may be spaced from each other to form a grid pattern. 
       FIG. 31  is a schematic cross-sectional view of a display device according to an embodiment. 
     Referring to  FIG. 31 , in a display device  10 _ 5  according to an embodiment, the light emitting element  300  may be located above a concave-convex pattern  750 _ 5 . For example, in the display device  10 _ 5 , a vertical dimension measured from the via layer  200  to a top side of the light emitting element  300  in a cross-sectional view may be larger than a vertical dimension measured from the via layer  200  to a bottom side of the concave-convex pattern  750 _ 5 . At least a portion of the concave-convex pattern  750 _ 5  may be located below a virtual plane parallel to a top side of the via layer  200  and flush with a top side of the light emitting element  300 . A third insulating pattern  730 _ 5  may be disposed on the light emitting elements  300 . 
     The display device  10  according to an embodiment may include the concave-convex pattern  750  such that the light emitted from the light emitting element  300  travels toward a top of each sub-pixel PXn. In the display device  10  as described above, the light emitted from the light emitting element  300  may be incident on the first insulating layer  600  or the second insulating layer  700 , may travel therein, and may be output to the outside through the concave-convex pattern  650 _ 3  or  750 . In contrast, in the display device  10 _ 5  in  FIG. 31 , the light emitted from the light emitting element  300  may be not incident on the first insulating layer  600  or the second insulating layer  700 , but may directly travel toward the concave-convex pattern  750 _ 5  and then may be reflected therefrom, and may be emitted toward the top of each sub-pixel PXn. 
     The concave-convex pattern  750 _ 5  of the display device  10 _ 5  according to an embodiment may have at least one side having an inclined shape with respect to a top side of each of a first insulating pattern  710 _ 5  and a second insulating pattern  720 _ 5  so that the light emitted from the light emitting element  300  may be reflected thereon. The inclined side of the concave-convex pattern  750 _ 5  has a predefined inclination angle with respect to a plane parallel to a top side of the via layer  200 . Light emitted from the light emitting element  300  and traveling in a parallel direction to the top side of the via layer  200  may be reflected from the inclined side of the concave-convex pattern  750 _ 5  and then may be mitted in an upward direction. In the display device  10 _ 5  in  FIG. 31 , the light may not be incident on the insulating pattern, thereby reducing the light loss, compared to the display device  10 . 
     In an embodiment, a structure of the light emitting element  300  is not limited to that as shown in  FIG. 3  and may have a different structure. 
       FIG. 32  is a schematic diagram of a light emitting element according to an embodiment. 
     Referring to  FIG. 32 , a light emitting element  300 ′ may be formed such that layers are not stacked in a direction, but each of the layers surrounds an outer side of adjacent another layer. The light emitting element  300 ′ in  FIG. 32  is the same as the light emitting element  300  in  FIG. 3 , except that a shape of each layer is different from that in the light emitting element  300  in  FIG. 3 . Hereinafter, the same contents will be omitted, and differences will be described. 
     According to an embodiment, a first conductive type semiconductor  310 ′ may extend in a direction, and each of both opposing ends thereof may be tapered toward the centers thereof. The first conductive type semiconductor  310 ′ in  FIG. 32  may have a rod-shaped or cylindrical body, and a conical portion on each of upper and lower ends of the body. A conical portion on the upper end of the body may have a steeper slope that that of the conical portion on the lower end thereof. 
     An active layer  330 ′ surrounds an outer side of the body of the first conductive type semiconductor  310 ′. The active layer  330 ′ may have an annular shape extending in a direction. The active layer  330 ′ does not surround each of the conical portions of the first conductive type semiconductor  310 ′. For example, the active layer  330 ′ may contact a side of the first conductive type semiconductor  310 ′ parallel thereto. 
     A second conductive type semiconductor  320 ′ surrounds an outer side of the active layer  330 ′ and the upper conical portion of the first conductive type semiconductor  310 ′. The second conductive type semiconductor  320 ′ may include an annular body extending in a direction and an upper conical portion on an upper end of the body. For example, the second conductive type semiconductor  320 ′ may directly contact a side of the active layer  330 ′ parallel thereto and an inclined side of the upper conical portion of the first conductive type semiconductor  310 ′. However, the second conductive type semiconductor  320 ′ does not surround the lower conical portion of the first conductive type semiconductor  310 ′. 
     An electrode material layer  370 ′ may be disposed to surround an outer side of the second conductive type semiconductor  320 ′. For example, a shape of the electrode material layer  370 ′ may be substantially the same as that of the second conductive type semiconductor  320 ′. For example, the electrode material layer  370 ′ may contact an entire area of the outer side of the second conductive type semiconductor  320 ′. 
     An insulating film  380 ′ may be disposed to surround an outer side of the electrode material layer  370 ′ and the outer side of the first conductive type semiconductor  310 ′. The insulating film  380 ′ may directly contact the outer side of the electrode material layer  370 ′, the lower conical portion of the first conductive type semiconductor  310 ′, and an exposed lower end of each of the active layer  330 ′ and the second conductive type semiconductor  320 ′. 
     In concluding the detailed description, those skilled in the art will appreciate that many variations and modifications can be made to the embodiments without substantially departing from the principles of the disclosure. Therefore, the disclosed embodiments of the disclosure are used in a generic and descriptive sense only and not for purposes of limitation.