Light emitting device, method of manufacturing the same, light emitting device package and lighting system

Abstract

A light emitting device includes an active layer formed between first and second semiconductor layers. The first semiconductor layer includes a first surface facing the active layer, a second surface opposing the first surface, and a side surface that includes a stepped portion. The stepped portion causes the side surface to extend beyond one of the first surface or second surface of the first semiconductor layer. A light emitting device may also be formed with a buffer layer that includes a stepped portion, and a light emitting device package and system may be formed from the light emitting devices.

1 . A light emitting device comprising:
 a first semiconductor layer;   a second semiconductor layer; and   an active layer between the first and second semiconductor layers, wherein the first semiconductor layer includes:   (a) a first surface facing the active layer,   (b) a second surface opposing the first surface, and   (c) a side surface that includes a stepped portion,   wherein the stepped portion causes the side surface to extend beyond one of the first surface or second surface.   
     
     
         2 . The device of  claim 1 , wherein an area of the first surface is greater than an area of the second surface. 
     
     
         3 . The device of  claim 2 , wherein the area of the second surface is less than the area of the first surface as a result of the stepped portion. 
     
     
         4 . The device of  claim 1 , wherein an area of the first surface is less than an area of the second surface. 
     
     
         5 . The device of  claim 1 , wherein the first semiconductor layer is a first conductivity type and the second semiconductor layer is a second conductivity type. 
     
     
         6 . The device of  claim 1 , further comprising:
 a buffer layer,   wherein a first semiconductor layer is located between the buffer layer and the active layer, the first semiconductor layer is of a first conductivity type, and the second semiconductor layer is of a second conductivity type.   
     
     
         7 . The device of  claim 6 , wherein the buffer layer is formed on a first portion of the first conductivity type semiconductor, and
 wherein the device further comprises:   a first electrode on the first semiconductor layer where the buffer layer is not formed, and   a second electrode under the second semiconductor layer.   
     
     
         8 . The device of  claim 7 , wherein the buffer layer is divided into first and second sections disposed on the first semiconductor layer, the first and second sections of the buffer layer separated to expose a portion of the first semiconductor layer, the first electrode electrically coupled to the exposed portion of the first semiconductor layer. 
     
     
         9 . The device of  claim 6 , wherein the buffer layer is an undoped layer. 
     
     
         10 . The device of  claim 6 , wherein the buffer layer is a doped layer. 
     
     
         11 . The device of  claim 1 , further comprising:
 at least one reflector to reflect light emitted from the active layer.   
     
     
         12 . The device of  claim 11 , wherein the reflector is located adjacent the first semiconductor layer. 
     
     
         13 . The device of  claim 12 , wherein the reflector includes:
 a protrusion that extends from a surface of a substrate that supports or is coupled to the first semiconductor layer.   
     
     
         14 . The device of  claim 1 , further comprising:
 at least one diffuser, located on the second surface of the first semiconductor layer, to diffuse light emitted from the active layer.   
     
     
         15 . The device of  claim 14 , wherein the diffuser extends into the second surface of the first semiconductor layer. 
     
     
         16 . The device of  claim 15 , wherein the diffuser includes a recess that extends into the second surface of the first semiconductor layer. 
     
     
         17 . A light emitting device comprising:
 a buffer layer;   a first semiconductor layer;   a second semiconductor layer; and   an active layer between the first and second semiconductor layers, wherein:   the first semiconductor layer is between the buffer layer and active layer,   the active layer is between the first and second semiconductor layers, and   wherein a bottom surface of the buffer layer has an area smaller than an area of at least one of the surfaces of the first semiconductor layer.   
     
     
         18 . The device of  claim 17 , wherein a side surface of the buffer layer includes:
 a stepped portion which causes a top surface of the buffer layer facing the first semiconductor layer to have an area greater than the bottom surface of the buffer layer.   
     
     
         19 . The device of  claim 17 , wherein a side surface of the buffer layer includes:
 a stepped portion which causes the side surface of the buffer layer to extend beyond at least one of a top surface or the bottom surface of the buffer layer.   
     
     
         20 . The device of  claim 17 , wherein the buffer layer is a doped layer. 
     
     
         21 . The device of  claim 17 , wherein the buffer layer is an undoped layer. 
     
     
         22 . The device of  claim 17 , further comprising:
 at least one reflector to reflect light emitted from the active layer.   
     
     
         23 . The device of  claim 22 , wherein the reflector is adjacent the buffer layer. 
     
     
         24 . The device of  claim 23 , wherein the reflector includes:
 a protrusion that extends from a surface of a substrate that supports or is coupled to the buffer layer.   
     
     
         25 . A light emitting device package comprising the light emitting device of  claim 1 . 
     
     
         26 . A light emitting device package comprising the light emitting device of  claim 17 . 
     
     
         27 . A lighting system comprising a light emitting device as recited in  claim 1 ,
 wherein said device is coupled to a substrate of a light emitting module.   
     
     
         28 . A method of manufacturing a light emitting device, comprising:
 forming a mask layer on a substrate to define a region of a light emitting device;   forming a semiconductor layer of a first conductivity type, an active layer, and a semiconductor layer of a second conductivity type at said region;   selectively removing the mask layer; and   forming first and second electrodes electrically coupled to the first and second semiconductor layers respectively, wherein one of the semiconductor layers is formed to include a first surface facing the active layer, a second surface opposing the first surface, and a side surface that includes a stepped portion, and wherein the stepped portion causes the side surface to extend beyond one of the first surface or second surface.   
     
     
         29 . A method of manufacturing a light emitting device, comprising:
 forming a mask layer on a substrate to define a region of a light emitting device;   forming a semiconductor layer of a first conductivity type, an active layer, and a semiconductor layer of a second conductivity type at said region;   selectively removing the mask layer; and   forming first and second electrodes electrically coupled to the first and second semiconductor layers respectively, wherein one of the semiconductor layers is formed to include a first surface facing the active layer, said method further comprising:   forming a buffer layer coupled to the first and second semiconductor layers and the active layer, wherein a bottom surface of the buffer layer has an area smaller than an area of at least one of the surfaces of the semiconductor layer of the first conductivity type or the second conductivity type.   
     
     
         30 . The method of  claim 29 , wherein the buffer layer includes a stepped portion that causes the bottom surface of the buffer layer to have an area smaller than an area of at least one of the surfaces of the semiconductor layer of the first conductivity type or the second conductivity type.