Light emitting diode and method for manufacturing the same

Abstract

Disclosed are a light emitting diode (LED) with high luminance and a method for manufacturing the same. The LED comprises a substrate, a first conductive clad layer formed on the substrate, an active layer formed on the first conductive clad layer, a second conductive clad layer formed on the active layer, an alumina (Al 2 O 3 ) layer formed on the lower surface of the substrate, and an aluminum layer formed on the lower surface of the alumina (Al 2 O 3 ) layer. Otherwise, the substrate is removed, the aluminum layer and the alumina layer are formed directly on the lower surface of the first conductive clad layer. Compared to a single reflective layer made of a metal, a reflective layer including the aluminum layer and the alumina layer improves reflective characteristics of the LED.

What is claimed is:  
     
         1 . A light emitting diode comprising: 
 a substrate;    a first conductive clad layer formed on the substrate;    an active layer formed on the first conductive clad layer;    a second conductive clad layer formed on the active layer;    an alumina (Al 2 O 3 ) layer formed on the lower surface of the substrate; and    an aluminum layer formed on the lower surface of the alumina (Al 2 O 3 ) layer.    
     
     
         2 . The light emitting diode as set forth in  claim 1 , further comprising a glass layer formed on the lower surface of the aluminum layer.  
     
     
         3 . The light emitting diode as set forth in  claim 1  or  2 , 
 further comprising an alumina (Al 2 O 3 ) layer formed on the lower surface of the aluminum layer or formed between the aluminum layer and the glass layer.  
 
     
     
         4 . The light emitting diode as set forth in  claim 1 , 
 wherein the first and second conductive clad layers are made of a semiconductor material of a GaN compound, and the substrate is a sapphire substrate.    
     
     
         5 . A light emitting diode comprising: 
 a glass layer;    an aluminum layer formed on the glass layer;    an alumina (Al 2 O 3 ) layer formed on the aluminum layer;    a first conductive clad layer formed on the alumina (Al 2 O 3 ) layer;    an active layer formed on the first conductive clad layer; and    a second conductive clad layer formed on the active layer.    
     
     
         6 . The light emitting diode as set forth in  claim 5 , 
 further comprising an alumina (Al 2 O 3 ) layer formed between the aluminum layer and the glass layer.    
     
     
         7 . The light emitting diode as set forth in  claim 5 , 
 wherein the first and second conductive clad layers are made of a semiconductor material of a GaN compound, and the substrate is a sapphire substrate.    
     
     
         8 . A method for manufacturing a light emitting diode (LED), comprising the steps of: 
 preparing a substrate;    forming a first conductive clad layer on the substrate;    forming an active layer on the first conductive clad layer;    forming a second conductive clad layer on the active layer; and    bonding the aluminum film to the lower surface of the substrate by heating and compressing the aluminum film and the substrate under an oxygen atmosphere so as to form an aluminum layer provided with an alumina (Al 2 O 3 ) layer at an interface thereof.    
     
     
         9 . The method for manufacturing a LED as set forth in  claim 8 , 
 wherein a heating temperature applied in the step of bonding the aluminum film to the substrate is in the range of 250° C. to 500° C.    
     
     
         10 . The method for manufacturing a LED as set forth in  claim 8 , 
 wherein a pressure applied to the substrate and the aluminum layer in the step of bonding the aluminum film to the substrate is at least 30 gf/cm 2 .    
     
     
         11 . The method for manufacturing a LED as set forth in  claim 8 , 
 wherein a DC voltage in the range of 300V to 600V is applied to the substrate in the step of bonding the aluminum film to the substrate.    
     
     
         12 . The method for manufacturing a LED as set forth in  claim 8 , 
 wherein a glass layer is bonded to the lower surface of the aluminum layer in the step of bonding the aluminum film to the substrate.    
     
     
         13 . The method for manufacturing a LED as set forth in  claim 8 , 
 wherein an alumina layer is additionally formed on the lower surface of the aluminum layer in the step of bonding the aluminum film to the substrate.    
     
     
         14 . The method for manufacturing a LED as set forth in  claim 8 , 
 wherein the first and second conductive clad layers are made of a semiconductor material of a GaN compound, and the substrate is a sapphire substrate.    
     
     
         15 . A method for manufacturing a light emitting diode (LED), comprising the steps of: 
 preparing a substrate;    forming a first conductive clad layer on the substrate;    forming an active layer on the first conductive clad layer;    forming a second conductive clad layer on the active layer;    removing the substrate so as to expose the lower surface of the first conductive clad layer to the outside;    successively disposing an aluminum film and a glass layer on the lower surface of the first conductive clad layer under an oxygen atmosphere; and    bonding the aluminum film to the first conductive clad layer and the glass layer to the aluminum film by heating and compressing the three layers.    
     
     
         16 . The method for manufacturing a LED as set forth in  claim 15 , 
 wherein a heating temperature applied in the bonding step is in the range of 250° C. to 500° C.    
     
     
         17 . The method for manufacturing a LED as set forth in  claim 15 , 
 wherein a pressure applied to the substrate and the aluminum layer in the bonding step is at least 30 gf/cm 2 .    
     
     
         18 . The method for manufacturing a LED as set forth in  claim 15 , 
 wherein an alumina layer is additionally formed on the lower surface of the aluminum film contacting the glass layer in the bonding step.    
     
     
         19 . The method for manufacturing a LED as set forth in  claim 15 , 
 wherein the first and second conductive clad layers are made of a semiconductor material of a GaN compound, and the substrate is a sapphire substrate.