Substrate-free light emitting diode chip

Abstract

A light emitting diode (LED) chip has a multilayer semiconductor structure that is at least 10 microns thick and does not require an attached growth substrate or transfer substrate for structural rigidity or support. The multilayer semiconductor structure includes a first doped layer, a second doped layer and an active region interposed between the first doped layer and the second doped layer. Optionally, the multilayer semiconductor structure includes an undoped layer. At least one of the layers of the multilayer semiconductor structure is at least 5 microns thick and is preferably deposited by hydride vapor phase epitaxy.

1 . An substrate-free, gallium-nitride-based light emitting diode chip comprising:
 a multilayer semiconductor structure that has a first side and an opposing second side and that includes a first doped layer proximal to said first side, an active region, a second doped layer proximal to said second side with said active region interposed between said first doped layer and said second doped layer;   a first electrode in electrical contact with said first doped layer; and   a second electrode in electrical contact with said second doped layer;   wherein said multilayer semiconductor has a total thickness of at least 10 microns and wherein said active region emits internally generated light when an electrical voltage is applied between said first electrode and said second electrode.   
     
     
         2 . The light emitting diode chip as in  claim 1 , wherein said multilayer semiconductor structure is at least 20 microns thick. 
     
     
         3 . The light emitting diode chip as in  claim 2 , wherein said multilayer semiconductor structure is at least 30 microns thick. 
     
     
         4 . The light emitting diode chip as in  claim 1 , wherein at least a portion of said first side of said multilayer semiconductor structure and at least a portion of said second side of said multilayer semiconductor structure transmit externally incident light. 
     
     
         5 . The light emitting diode chip as in  claim 4 , wherein said light emitting diode chip transmits at least 60 percent of said externally incident light that is directed to said first side or said second side of said multiplayer semiconductor structure. 
     
     
         6 . The light emitting diode chip as in  claim 5 , wherein said light emitting diode chip transmits at least 70 percent of said externally incident light. 
     
     
         7 . The light emitting diode chip as in  claim 6 , wherein said light emitting diode chip transmits at least 80 percent of said externally incident light. 
     
     
         8 . The light emitting diode chip as in  claim 1 , further comprising a reflective surface covering substantially all of said first side or substantially all of said second side of said multilayer semiconductor structure, wherein said reflective surface reflects externally incident light. 
     
     
         9 . The light emitting diode chip of  claim 8 , wherein said reflective surface is said first electrode or said second electrode. 
     
     
         10 . The light emitting diode chip as in  claim 8 , wherein said light emitting diode chip reflects at least 60 percent of said externally incident light that is directed to said multiplayer semiconductor structure. 
     
     
         11 . The light emitting diode chip as in  claim 10 , wherein said light emitting diode chip reflects at least 70 percent of said externally incident light. 
     
     
         12 . The light emitting diode chip as in  claim 11 , wherein said light emitting diode chip reflects at least 80 percent of said externally incident light. 
     
     
         13 . The light emitting diode chip as in  claim 1 , wherein said multiplayer semiconductor structure has an absorption coefficient less that 20 per centimeter. 
     
     
         14 . The light emitting diode chip as in  claim 13 , wherein said multiplayer semiconductor structure has an absorption coefficient less that 10 per centimeter. 
     
     
         15 . The light emitting diode chip as in  claim 14 , wherein said multiplayer semiconductor structure has an absorption coefficient less that 5 per centimeter. 
     
     
         16 . The light emitting diode chip as in  claim 15 , wherein said multiplayer semiconductor structure has an absorption coefficient less that 2 per centimeter. 
     
     
         17 . The light emitting diode chip as in  claim 1 , wherein said first doped layer or said second doped layer is at least 5 microns thick and is fabricated by hydride vapor phase epitaxy. 
     
     
         18 . The light emitting diode chip as in  claim 17 , wherein said first doped layer or said second doped layer is at least 10 microns thick. 
     
     
         19 . The light emitting diode chip as in  claim 18 , wherein said first doped layer or said second doped layer is at least 15 microns thick. 
     
     
         20 . The light emitting diode chip as in  claim 19 , wherein said first doped layer or said second doped layer is at least 25 microns thick. 
     
     
         21 . The light emitting diode chip as in  claim 1 , wherein said multiplayer semiconductor structure includes a substantially undoped layer adjacent to said first side or said second side, wherein said undoped layer is at least 5 microns thick and wherein said undoped layer is fabricated by hydride vapor phase epitaxy. 
     
     
         22 . The light emitting diode chip as in  claim 21 , wherein said undoped layer is at least 10 microns thick. 
     
     
         23 . The light emitting diode chip as in  claim 22 , wherein said undoped layer is at least 15 microns thick. 
     
     
         24 . The light emitting diode chip as in  claim 23 , wherein said undoped layer is at least 25 microns thick. 
     
     
         25 . The light emitting diode chip as in  claim 1 , wherein said first doped layer is an n-doped layer and said second doped layer is a p-doped layer.