Substrate having concave-convex pattern, light-emitting diode including the substrate, and method for fabricating the diode

Abstract

Provided are a substrate having concave-convex patterns, a light-emitting diode (LED) including the substrate, and a method of fabricating the LED. The LED includes a substrate, and concave-convex patterns disposed in an upper surface of the substrate and having convexes and concaves defined by the convexes. Unit light-emitting device having a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer disposed on the substrate in sequence is present.

1 . A light-emitting diode (LED), comprising:
 a substrate;   concave-convex patterns disposed in an upper surface of the substrate, the concave-convex patterns comprising:
 convex portions, each convex portion comprising facets that are crystal planes; and 
 concave portions defined by the convex portions; and 
   a unit light-emitting device comprising:
 a first conductive semiconductor layer disposed on the substrate; 
 an active layer disposed on the first conductive semiconductor layer; and 
 a second conductive semiconductor layer disposed on the active layer. 
   
     
     
         2 . The LED of  claim 1 , wherein each of the convex portions further comprises an upper vertex formed by some of the facets in contact with each other. 
     
     
         3 . The LED of  claim 2 , wherein:
 the facets comprise lower facets that are first crystal planes and upper facets that are second crystal planes; and   the upper vertex is formed by the second crystal planes in contact with each other.   
     
     
         4 . The LED of  claim 3 , wherein an inclination angle of the second crystal planes with respect to a surface of the substrate is smaller than an inclination angle of the first crystal planes with respect to the surface of the substrate. 
     
     
         5 . The LED of  claim 4 , wherein the convex portions have a stripe or island shape. 
     
     
         6 . The LED of  claim 5 , wherein, when the convex portions have the island shape, bottom surfaces of the convex portions are in a triangle-like shape, each line segment of the triangle-like shape being arcuately formed and projected to the outside of the triangle-like shape. 
     
     
         7 . The LED of  claim 1 , wherein each of the convex portions further comprises a flat upper surface. 
     
     
         8 . The LED of  claim 1 , wherein the concave-convex patterns disposed in a partial area of the substrate comprise pits in surfaces of the concave-convex patterns. 
     
     
         9 . The LED of  claim 8 , wherein:
 the unit light-emitting device is one of a plurality of unit light-emitting devices, adjacent unit light-emitting devices being separated by a separation groove; and   the concave-convex patterns comprising the pits are disposed in the separation groove.   
     
     
         10 . The LED of  claim 9 , further comprising:
 a separating insulating layer disposed in the separation groove; and   an interconnection disposed on the separating insulating layer, the interconnection electrically connecting a pair of adjacent unit light-emitting devices of the plurality of unit light-emitting devices.   
     
     
         11 . The LED of  claim 8 , wherein:
 each of the unit light-emitting devices further comprises a mesa-etched region in an upper surface thereof, the mesa-etched region exposing the first conductive semiconductor layer; and   the concave-convex patterns comprising the pits are disposed in an area corresponding to the mesa-etched regions.   
     
     
         12 . A substrate for a light-emitting diode (LED) comprising:
 concave-convex patterns disposed in an upper surface of the substrate, each concave-convex pattern comprising convex portions and concave portions defined by the convex portions,   wherein the convex portions comprise facets that are crystal planes.   
     
     
         13 . A method of fabricating a light-emitting diode (LED), comprising:
 forming an etching mask pattern on a substrate;   forming concave-convex patterns in a surface of the substrate by wet-etching the substrate using the etching mask pattern as a mask, the concave-convex patterns comprising convex portions and concave portions defined by the convex portions; and   forming a stacked body comprising:
 a first conductive semiconductor layer disposed on the substrate; 
 an active layer disposed on the first conductive semiconductor layer; and 
 a second conductive semiconductor layer disposed on the active layer. 
   
     
     
         14 . The method of  claim 13 , wherein forming the concave-convex patterns comprises:
 dry-etching the substrate using the etching mask pattern as a mask before or after wet-etching the substrate.   
     
     
         15 . The method of  claim 13 , wherein:
 the wet-etching is a first wet-etching;   each of the convex portions further comprises an upper surface, and   the method further comprises:
 exposing, after the first wet-etching, the upper surfaces of the convex portions by removing the etching mask pattern; and 
 altering, after exposing the upper surfaces, each of the convex portions to comprise an upper vertex formed by some of the facets in contact with each other by a second wet-etching of the substrate. 
   
     
     
         16 . The method of  claim 13 , wherein, in the wet etching process, an etching solution is utilized to penetrate below the etching mask pattern, such that each of the convex portions is formed comprising the facets and an upper vertex formed by some of the facets in contact with each other. 
     
     
         17 . The method of  claim 16 , wherein a width of the etching mask pattern is 0.2 to 1 μm. 
     
     
         18 . The method of  claim 15 , wherein each of the convex portions comprises:
 lower facets that are first crystal planes;   upper facets that are second crystal planes; and   the upper vertex formed by the second crystal planes in contact with each other.   
     
     
         19 . The method of  claim 18 , wherein:
 the first crystal planes are inclined at a first inclination angle with respect to a surface of the substrate;   the second crystal planes are inclined at a second inclination angle with respect to the surface of the substrate; and   the second inclination angle is smaller than the first inclination angle.   
     
     
         20 . The method of  claim 13 , further comprising:
 forming pits in surfaces of concave-convex patterns disposed in a partial area of the upper surface of the substrate.   
     
     
         21 . The method of  claim 20 , wherein forming the pits comprises:
 forming a metal layer on the concave-convex patterns;   forming metal clusters by heat-treating the metal layer; and   etching surfaces of the concave-convex patterns using the metal clusters as a mask.   
     
     
         22 . The method of  claim 21 , further comprising:
 forming, before etching the surfaces of the concave-convex patterns, a photoresist pattern on the concave-convex patterns disposed in another area of the upper surface of the substrate,   wherein etching the surfaces of the concave-convex patterns is performed using the metal clusters and the photoresist pattern as a mask.   
     
     
         23 . The method of  claim 20 , further comprising:
 forming a separation groove exposing concave-convex patterns by etching a partial area of the stacked body until the substrate is exposed to separate adjacent unit light-emitting devices,   wherein forming the pits in the surfaces of the concave-convex patterns comprises forming the pits in surfaces of the concave-convex patterns exposed by the separation groove.   
     
     
         24 . The method of  claim 23 , wherein forming the pits comprises:
 forming a metal layer on the concave-convex patterns exposed by the separation groove and on the unit light-emitting devices;   forming metal clusters by heat-treating the metal layer;   forming a photoresist pattern on the unit light-emitting devices; and   etching surfaces of the concave-convex patterns using the metal clusters and the photoresist pattern as a mask.   
     
     
         25 . The method of  claim 20 , further comprising:
 forming a mesa-etched region by etching a partial area of the stacked body until the first conductive semiconductor layer is exposed,   wherein the concave-convex patterns comprising the pits are disposed in an area corresponding to the mesa-etched region.