Patent Publication Number: US-2015069440-A1

Title: Light emitting diode and method of manufacturing the same

Description:
TECHNICAL FIELD 
     The present inventive concept disclosed herein relates to a light emitting diode, and more particularly, to a light emitting diode having a nanostructure capping pattern and a method of manufacturing the same. 
     BACKGROUND ART 
     A light emitting diode (LED), a type of P-N junction diode, is a semiconductor device using electroluminescence, a phenomenon in which monochromatic light emits when a forward voltage is applied, and a wavelength of light emitted from the light emitting diode is determined by bandgap energy (Eg) of a material used therein. In an initial stage of light emitting diode technique, light emitting diodes capable of emitting infrared and red light had been mainly developed and blue LEDs have been actively studied after Nakamura of Nichia Chemical discovered that blue light can be generated by using GaN in 1993. Since white color may be made through a combination of red, green and blue colors, development of the blue light emitting diode based on GaN along with the already developed red and green light emitting diodes made possible to realize a white light emitting diode. 
     Meanwhile, in order to increase marketability of a light emitting diode, there is a need for increasing light-emitting efficiency and lifetime of the light emitting diode. 
     However, with respect to the blue light emitting diode based on GaN, only a portion of light generated in an active layer is used for emitting light and most of the generated light is reabsorbed in the diode to become extinct. As a result, external quantum efficiencies of most of blue light emitting diodes remain at a level of about 54%, but various techniques for increasing the light-emitting efficiency have recently been studied. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     The present inventive concept provides a nanostructure capping pattern covering a nanostructure to increase an external light-emitting efficiency and prevent damage of the nanostructure, which may occur during a manufacturing process. 
     The object of the present inventive concept is not limited to the aforesaid, but other objects not described herein will be clearly understood by those skilled in the art from descriptions below. 
     Solution to Problem 
     Embodiments of the present inventive concept provide light emitting diodes including: a light-emitting structure including a first semiconductor layer, a second semiconductor layer, and an active layer between the first and second semiconductor layers; a nanostructure provided on the light-emitting structure; and a nanostructure capping pattern covering the nanostructure, wherein a refractive index of the nanostructure capping pattern may be higher than a refractive index of air and lower than a refractive index of the nanostructure. 
     In some embodiments, the nanostructure capping pattern may include a plurality of layers having different refractive indices and the refractive indices of the plurality of layers may gradually decrease from the layer in contact with the nanostructure to the layer in contact with air. 
     In other embodiments, the nanostructure capping pattern may include metal oxide. The metal oxide may include at least one of MgO, SiO, BeO, Lu 2 O 3 , Ta 2 O 5 , Y 2 O 3 , Yb 2 O 3 , and Al 2 O 3 . 
     In still other embodiments, the nanostructure capping pattern may include at least one of nickel (Ni), palladium (Pd), platinum (Pt), titanium (Ti), gold (Au), and copper (Cu). 
     In even other embodiments, a thickness of the nanostructure capping pattern may be in a range of about 100 Å to about 1000 Å 
     In yet other embodiments, the nanostructure capping pattern may cover a top surface and side surfaces of the nanostructure. 
     In further embodiments, the light emitting diode may further include a transparent electrode layer on the light-emitting structure, and the nanostructure may be provided on a surface of the transparent electrode layer. 
     In still further embodiments, the light emitting diode may further include a transparent electrode layer including a trench on the light-emitting structure, and the nanostructure may be provided in the trench. 
     In even further embodiments, the nanostructure may be provided on a surface of the first semiconductor layer. 
     In yet further embodiments, the nanostructure capping pattern may expose first and second electrodes. 
     In much further embodiments, the light emitting diode may further include metal islands in contact with the nanostructure. 
     In other embodiments of the present inventive concept, methods of manufacturing a light emitting diode include: forming a light-emitting structure including a first semi-conductor layer, a second semiconductor layer, and an active layer provided between the first and second semiconductor layers; forming a nanostructure on the light-emitting structure; forming a nanostructure capping pattern covering the nanostructure; and respectively forming a first electrode and a second electrode on the first semi-conductor layer and the second semiconductor layer, wherein a refractive index of the nanostructure capping pattern may be higher than a refractive index of air and lower than a refractive index of the nanostructure, and the nanostructure capping pattern may be formed earlier than the first and second electrodes. 
     In some embodiments, the forming of the nanostructure capping pattern may include depositing a plurality of layers having different refractive indices and the plurality of layers may be formed to allow the refractive indices to gradually decrease from the layer in contact with the nanostructure to the layer in contact with air. 
     In other embodiments, the forming of the nanostructure may include: forming a metal catalyst layer on the light-emitting structure; heat treating the metal catalyst layer to form metal islands; and using the metal islands as seeds to grow nanowires. 
     Advantageous Effects of Invention 
     A light emitting diode including a nanostructure capping pattern is provided and thus, an external light-emitting efficiency may increase and damage of a nanostructure, which may occur during a manufacturing process, may be prevented. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the present inventive concept, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present inventive concept and, together with the description, serve to explain principles of the present inventive concept. In the drawings: 
         FIGS. 1 and 2  are plan view and cross-sectional view illustrating a light emitting diode according to an embodiment of the present inventive concept, respectively; 
         FIG. 3  is an enlarged view illustrating a nanostructure and a nanostructure capping pattern of  FIGS. 1 and 2 ; 
         FIGS. 4 and 5  are plan view and cross-sectional view illustrating a light emitting diode according to another embodiment of the present inventive concept, respectively; 
         FIGS. 6 and 7  are cross-sectional views illustrating light emitting diodes according to other embodiments of the present inventive concept; 
         FIG. 8  is a flowchart for explaining a method of manufacturing a light emitting diode according to an embodiment of the present inventive concept; and 
         FIGS. 9 and 10  are cross-sectional views for explaining the method of manufacturing a light emitting diode according to the embodiment of the present inventive concept. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Advantages and features of the present inventive concept, and implementation methods thereof will be clarified through following embodiments described with reference to the accompanying drawings. The present inventive concept 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 fully convey the scope of the present inventive concept to those skilled in the art. Further, the present inventive concept is only defined by scopes of claims. Like reference numerals refer to like elements throughout. 
     In the specification, it will be understood that when a layer, such as a conductive layer, a semiconductor layer, or an insulating 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. Also, though terms like a first, a second, and a third are used to describe various regions and layers in various embodiments of the present inventive concept, these terms are used only to discriminate one region or layer from another region or layer, and the regions and the layers are not limited to these terms. 
     In the following description, the technical terms are used only for explaining a specific exemplary embodiment while not limiting the present inventive concept. The terms of a singular form may include plural forms unless referred to the contrary. The meaning of “omprises” and/or “omprising” specifies a property, a region, a fixed number, a step, a process, an element and/or a component but does not exclude other properties, regions, fixed numbers, steps, processes, elements and/or components. 
     Additionally, the embodiment in the detailed description will be described with sectional views as ideal exemplary views of the present inventive concept. In the figures, the dimensions of layers and regions are exaggerated for clarity of illustration. Accordingly, shapes of the exemplary views may be modified according to manufacturing techniques and/or allowable errors. Therefore, the embodiments of the present inventive concept are not limited to the specific shape illustrated in the exemplary views, but may include other shapes that may be created according to manufacturing processes. For example, an etch region illustrated with right angles may be rounded or be configured with a predetermined curvature. Therefore, areas exemplified in the drawings have general properties, and are used to illustrate specific shapes of certain regions. Thus, this should not be construed as limited to the scope of the present inventive concept. 
     Hereinafter, a light emitting diode according to an embodiment of the present inventive concept and a method of manufacturing the light emitting diode will be described in detail with reference to the accompanying drawings. 
     Referring to  FIGS. 1 to 3 , a light emitting diode according to an embodiment of the present inventive concept is provided.  FIG. 1  is a plan view illustrating the light emitting diode according to the embodiment of the present inventive concept and FIG.  2  is a cross-sectional view taken along line A-A′ of  FIG. 1 .  FIG. 3  is an enlarged view illustrating a nanostructure and a nanostructure capping pattern of  FIGS. 1 and 2 . 
     Referring to  FIGS. 1 to 3 , a light-emitting structure  120  may be provided on a substrate  100 . The substrate  100  may be a sapphire, SiC, GaN, Si, or GaAs substrate, and single crystal oxide having a lattice constant close to a lattice constant of a nitride semiconductor may be used. The light-emitting structure  120  may include a first semi-conductor layer  121 , an active layer  122 , and a second semiconductor layer  123 . A buffer layer  110  may be provided between the substrate  100  and the first semi-conductor layer  121 . The buffer layer  110  may be an Al x Ga y N 1-x-y  layer (0&lt;x&lt;1, 0&lt;y&lt;1). Symbols such as x and y are used in order to express compositions in the present specification, but the symbols do not express a specific composition, and use of the same symbol does not refer to having the same composition. The buffer layer  110  may be a seed layer for forming an epitaxial layer from the substrate  100 . The buffer layer  110  may decrease crystal defects generated due to differences in lattice constants and thermal expansion coefficients of the substrate  100  and the nitride semiconductor. 
     For example, the first semiconductor layer  121  may include an n-type contact layer and an n-type clad layer. The second semiconductor layer  123  may include a p-type contact layer and a p-type clad layer. The first semiconductor layer  121  may be an n-type Ga x N 1-x  layer (0&lt;x&lt;1). The active layer  122  may include a multi quantum well (MQW) layer. The multi quantum well layer may emit light by recombination of electrons and holes. For example, the active layer  122  may be an In x Ga 1-x N layer (0&lt;x&lt;1). The second semiconductor layer  123  may be a p-type Ga x N 1-x  layer (0&lt;x&lt;1). 
     A transparent electrode layer  131  may be provided on the light-emitting structure  120 . The transparent electrode layer  131  may transmit light radiating from the active layer  122  and may diffuse a current from a second electrode to be described below to an entire region of an upper surface of the light-emitting structure  120 . The transparent electrode layer  131  may be a material including nickel (Ni) and gold (Au), or indium tin oxide (ITO). First electrode  142  and second electrode  141  are provided on the first semiconductor layer  121  and the transparent electrode layer  131 , respectively. The first electrode  142  and the second electrode  141  are not limited to have shapes shown in  FIG. 1 , and may have various shapes, such as a circular, oval, rectangular, or triangular shape. The first electrode  142  and the second electrode  141  may include at least one of silver (Ag), aluminum (Al), gold (Au), palladium (Pd), nickel (Ni), zinc (Zn), molybdenum (Mo), tungsten (W), chromium (Cr), titanium (Ti), europium (Eu), platinum (Pt), and manganese (Mn). 
     A first nanostructure  156  may be provided on the transparent electrode layer  131 . The first nanostructure  156  may be provided in a first trench  113  formed in the transparent electrode layer  131 . For example, the first trench  113  may surround at least a portion of the first electrode  142 . The first nanostructure  156  may be Zn x O 1-x  nanowires (0&lt;x&lt;1). The nanowires may be aligned in a direction substantially perpendicular to a bottom surface of the trench. The Zn x O 1-x  nanowires (0&lt;x&lt;1) have a diameter of about 100 nm or less and a height ranging from about 10 nm to about 1 μm, and thus, may be hair-shape nanostructures having a high aspect ratio. A refractive index of the first nanostructure  156  may be an intermediate value between a refractive index of the transparent electrode layer  131  and a refractive index of air. For example, when the refractive index of the transparent electrode layer  131  is 2.35 and the refractive index of air is 1.0, the refractive index of the first nanostructure  156  may be a value between 1.0 and 2.35. For example, when the first nanostructure  156  is Zn x O 1-x  nanowires (0&lt;x&lt;1), the refractive index of the first nanostructure  156  may be about 2.0. Therefore, the first nanostructure  156  may improve a light-emitting efficiency of the light-emitting diode by reducing reflection of the light generated from the active layer  122  at an interface between the transparent electrode layer  131  and air. For the simplicity of the description, only a single first trench  113  having the first nanostructure  156  provided therein is illustrated, but a plurality of the first trenches  113  may be formed in the transparent electrode layer  131 , and the first nanostructure  156  may be formed in each of the plurality of first trenches  113 . In this case, a nanostructure capping pattern to be described below may cover each of the plurality of first trenches  113 . 
     Metal islands  155  in contact with the first nanostructure  156  may be provided. The metal islands  155  may be attached to an upper portion or intermediate portion of the first nanostructure  156 , or may be provided on the bottom surface of the first trench  113 . The metal islands  155  may be seeds for forming the Zn x O 1-x  nanowires (0&lt;x&lt;1) as described in a manufacturing method below. The metal islands  155  may include at least one of Au, cobalt (Co), lead (Pb), Pt, and Ni. 
     A nanostructure capping pattern  171  covering the first nanostructure  156  may be provided. A refractive index of the nanostructure capping pattern  171  may be higher than that of air and lower than that of the first nanostructure  156 . For example, when the refractive index of air is 1.0 and the refractive index of the first nanostructure  156  is 2.0, the refractive index of the nanostructure capping pattern  171  may be greater than 1.0 and smaller than 2.0. When the refractive index of the nanostructure capping pattern  171  is higher than that of air and lower than that of the first nanostructure  156 , an amount of light not reflecting at an end of the first nanostructure  156  but radiating to the outside may increase. Such a phenomenon may be explained according to Snell s law in Equation 1. 
     
       
         
           
             
               
                 Sin 
                  
                 
                     
                 
                  
                 
                   θ 
                   1 
                 
               
               
                 Sin 
                  
                 
                     
                 
                  
                 
                   θ 
                   2 
                 
               
             
             = 
             
               
                 n 
                 2 
               
               
                 n 
                 1 
               
             
           
         
       
     
     (θ 1  is an incident angle for transmitting the first nanostructure, θ 2  is a refraction angle for refracting from the nanostructure capping pattern, n 1  is a refractive index of the first nanostructure, and n 2  is a refractive index of the nanostructure capping pattern) 
     That is, a critical angle of θ 1  at which a total reflection (θ 2 =90°) occurs may increase as the refractive index n 2  of the nanostructure capping pattern  171  is higher. Such a phenomenon may be similarly applied to an interface between the nanostructure capping pattern  171  and air, and thus, when the refractive index of the nanostructure capping pattern  171  is an intermediate value between the refractive index of air and the refractive index of the first nanostructure  156 , the light-emitting efficiency of the light emitting diode may increase because possibility of the light generated from the active layer  122  being emitted to the outside increases. 
     The nanostructure capping pattern  171  may be a single layer. In another embodiment of the present inventive concept, the nanostructure capping pattern  171  may include a plurality of layers having different refractive indices and the refractive indices of the plurality of layers may gradually decrease from the layer in contact with the first nanostructure  156  to the layer in contact with air. For example, the nanostructure capping pattern  171  may include four layers, L 1 , L 2 , L 3 , and L 4 , as shown in  FIG. 3 , and refractive indices of the four layers may satisfy L 1 &gt;L 2 &gt;L 3 &gt;L 4 . 
     A material for the nanostructure capping pattern 171 may include at least one of materials in Table 1. When the nanostructure capping pattern  171  includes a plurality of layers having different refractive indices as described above, the plurality of layers may be selected from Table 1 so as to allow the refractive indices to gradually decrease from the layer in contact with the first nanostructure  156  to the layer in contact with air. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Oxide base 
                 Metal base 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Material 
                 Refractive index 
                 Material 
                 Refractive index 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 MgO 
                 1.75 
                 Ni 
                 1.628 
               
               
                   
                 SiO 
                 1.55 
                 Pd 
                 1.4 
               
               
                   
                 BeO 
                 1.7 
                 Pt 
                 1.84 
               
               
                   
                 Lu 2 O 3   
                 1.92 
                 Ti 
                 1.69 
               
               
                   
                 Ta 2 O 5   
                 1.79 
                 Au 
                 1.5 
               
               
                   
                 Y 2 O 3   
                 1.92 
                 Cu 
                 1.16 
               
               
                   
                 Yb 2 O 3   
                 1.94 
                 — 
                 — 
               
               
                   
                 Al 2 O 3   
                 1.67 
                 — 
                 — 
               
               
                   
                   
               
            
           
         
       
     
     A thickness of the nanostructure capping pattern  171  may be in a range of about 100 Å to about 1000 Å. The nanostructure capping pattern  171  may be restrictively provided on the first nanostructure  56  and may expose the first and second electrodes  141  and  142 . Alternatively, a portion of the nanostructure capping pattern  171  may exist between the nanowires constituting the first nanostructure  156 . 
       FIGS. 4 and 5  are plan view and cross-sectional view illustrating a light emitting diode according to another embodiment of the present inventive concept, respectively.  FIG. 5  is a cross-sectional view taken along line A-A′ of  FIG. 4 . For the simplicity of the description, the description related to the overlapping configuration will not be provided. 
     In the embodiment of the present inventive concept, a second nanostructure  153  may be provided in a second trench  115  formed in the first semiconductor layer  121 . The second trench  115  may surround at least a portion of the first electrode  142 . The second nanostructure  153  may be Zn x O 1-x  nanowires (0&lt;x&lt;1). Metal islands  152  in contact with the second nanostructure  153  may be provided. The second nanostructure  153  and the metal islands  152  may be substantially the same structure and material as the foregoing first nanostructure  156  and metal islands  155 . 
     Nanostructure capping patterns  172  respectively covering the first and second nanostructures  153  and  156  may be provided. A shape of the nanostructure capping pattern  172  is not limited thereto and any shape covering the first and second nanostructures  153  and  156  may be possible. For example, the nanostructure capping pattern  172  may be provided on the first and second nanostructures  153  and  156  in each separate form. The nanostructure capping pattern  172  may include a plurality of layers as shown in  FIG. 3 . For the simplicity of the description, only one first trench  113  having the first nanostructure  156  provided therein is illustrated, but a plurality of the first trenches  113  may be formed in the transparent electrode layer  131  and the first nanostructure  156  may be formed in each of the plurality of first trenches  113 . In this case, the nanostructure capping pattern  172  may cover each of the plurality of first trenches  113 . 
       FIGS. 6 and 7  are cross-sectional views illustrating light emitting diodes according to other embodiments of the present inventive concept. For the simplicity of the description, the description related to the overlapping configuration will not be provided. 
     A second electrode  144  may be provided on a structure support layer  182 . The structure support layer  182  may support a light-emitting structure after separation of a substrate (not shown). The structure support layer  182  may be formed of a silicon substrate or a metal substrate. The structure support layer  182  may be attached to the second electrode  144  by an adhesive layer  181 . The adhesive layer  181  may include at least one of gold (Au), indium (In), palladium (Pd), and tin (Sn). 
     A light-emitting structure  120  may be provided on the second electrode  144 . The light-emitting structure  120  may include a first semiconductor layer  121 , a second semiconductor layer  123 , and an active layer  122  between the first and second semi-conductor layers  121  and  123 . A reflective layer  167  may be provided between the light-emitting structure  120  and the second electrode  144 . The reflective layer  167  may be formed of metal including at least one of Al, Ag, copper (Cu), AgCu, Ni, rhodium (Rh), Pd, Pt, ruthenium (Ru), and Au, or may include conductive metal oxides such as MgZnO doped with TiO, NiO, indium, or gallium, InO doped with gallium, or ZnO doped with gallium. The reflective layer  167  may reflect light, which is generated from the active layer  122  and emitted in a direction of the second semiconductor layer  123 , to a direction of the first semiconductor layer  121 . In another embodiment of the present inventive concept, the reflective layer  167  is not provided and a portion of the second electrode  144  may act as a reflective layer. 
     A transparent electrode layer  131  and a first electrode  143  may be sequentially provided on the light-emitting structure  120 . A nanostructure  158  may be provided on a surface of the transparent electrode layer  131 . The nanostructure  158  may cover an entire surface of the exposed transparent electrode layer  131  as shown in  FIG. 6  or may be provided in a cluster form separated from one another on the transparent electrode layer  131  as shown in  FIG. 7 . Metal islands  157  in contact with the nanostructure  158  may be provided. 
     A nanostructure capping pattern  173  covering the nanostructure  158  may be provided. The nanostructure capping pattern  173  may cover a top surface and side surfaces of the nanostructure  158 . For example, when the nanostructure  158  includes mutually separated clusters as shown in  FIG. 7 , the nanostructure capping pattern  173  may cover a top surface and side surfaces of the each cluster constituting the nanostructure  158 . The nanostructure capping pattern  173  may include a plurality of layers as show in  FIG. 3 . Structures of  FIGS. 6 and 7  may be applied to the embodiments of  FIGS. 2 and 5 . That is, the first nanostructure  156  in the embodiments of  FIGS. 2 and 5  may be formed on the surface of the transparent electrode layer  131  without a trench as in the nanostructure  158  of  FIGS. 6 and 7 . 
       FIG. 8  is a flowchart for explaining a method of manufacturing a light emitting diode according to an embodiment of the present inventive concept.  FIGS. 9 and 10  are cross-sectional views for explaining the method of manufacturing a light emitting diode according to the embodiment of the present inventive concept. For the simplicity of the description, the following manufacturing method is described based on the light emitting diode according to the embodiment of  FIGS. 1 to 3 , but may be identically or similarly applied to the embodiments of  FIGS. 4 to 7 . 
     Referring to  FIGS. 8 and 9 , A metal catalyst layer  151  may be formed on a first trench  113  formed in the transparent electrode layer  131  (S 1 ). The metal catalyst layer  151  may be formed of a material including at least one of Au, Co, Pb, Pt, and Ni. The metal catalyst layer  151  may be formed by electron-beam evaporation, sputtering, or metalorganic chemical vapor deposition (MOCVD) after masking a portion other than the first trench  113  with a mask. The forming of the first trench  113  and the forming of the metal catalyst layer  151  may be performed by using the same mask. 
     Referring to  FIGS. 8 and 10 , Metal islands  155  may be formed by heat treating the metal catalyst layer  151  (S 2 ). The heat treatment process may be performed within a temperature range of about 300° C. to about 900° C. The metal catalyst layer  151  may become nano-sized metal islands  155  by the heat treatment. A size of the metal islands  155  may be in a range of a few Å to a few hundreds nanometer. A first nanostructure  156  may be formed by using the metal islands  155  as seeds (S 2 ). The first nanostructure  156  may be Zn x O 1-x  nanowires (0&lt;x&lt;1). The nanowires may be grown between a bottom surface of the first trench  113  and the metal islands  155  or may be grown from an upper portion of the metal islands  155 . Therefore, after completion of the growth, the metal islands  155  may exist under the first nanostructure  156  or may exist at an upper portion or an intermediate portion of the first nanostructure  156 . For the sake of convenience,  FIG. 10  illustrates that the metal islands  155  exist on the first nanostructure  156 . The nanowires may be grown from the metal islands  155  by charging zinc oxide (ZnO) powder or zinc (Zn) powder into a reaction furnace of a thermal chemical vapor deposition (CVD) equipment and supplying Ar gas and N 2  gas. Also, the nanowires may be formed by molecular beam epitaxy (MBE). Further, the nanowires may be formed by metalorganic CVD (MOCVD) by using a precursor, such as dimethyl-zinc (DMZn), and O 2  gas. The forming of the metal islands  155  and the forming of the first nanostructure  156  may be performed in the same reaction furnace. 
     A nanostructure capping pattern  171  may be formed on the first nanostructure  156  (S 3 ). A refractive index of the nanostructure capping pattern  171  may be higher than that of air and may be lower than that of the first nanostructure  156 . For example, when the refractive index of air is 1.0 and the refractive index of the first nanostructure  156  is 2.0, the refractive index of the nanostructure capping pattern  171  may be greater than 1.0 and smaller than 2.0. The nanostructure capping pattern  171  may include a plurality of layers having different refractive indices as shown in  FIG. 3  and the refractive indices of the plurality of layers may gradually decrease from the layer in contact with the first nanostructure  156  to the layer in contact with air. 
     The nanostructure capping pattern  171  may be formed by various methods according to the type of materials described in Table 1. For example, the nanostructure capping pattern  171  may be formed by sputtering, e-beam evaporation, MOCVD, or atomic layer deposition (ALD). The formation of the nanostructure capping pattern  171  may include an etching process using a photoresist. The transparent electrode layer  131  and the first semiconductor layer  121  may be exposed by the etching process. 
     Referring to  FIGS. 1 and 2  again, a first electrode  142  and a second electrode  141  may be formed on the first semiconductor layer  121  and the transparent electrode layer  131 , respectively (S 4 ). That is, the nanostructure capping pattern  171  may be formed earlier than the electrodes  141  and  142 . The nanostructure capping pattern  171  may prevent damage or separation of the first nanostructure  156  during a process after the forming of the first nanostructure  156 , such as the forming of the electrodes  141  and  142 . 
     The above detailed description exemplifies and explains the present inventive concept. Also, the foregoing description is merely provided to present and describe preferred embodiments of the present inventive concept. The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the present inventive concept. Thus, to the maximum extent allowed by law, the scope of the present inventive concept is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description. 
     INDUSTRIAL APPLICABILITY 
     The present inventive concept may be used in semiconductor device, especially in LED industry.