Gallium-nitride based light emitting diode light emitting layer structure

Abstract

A number of light-emitting layer structures for the GaN-based LEDs that can increase the lighting efficiency of the GaN-based LEDs on one hand and facilitate the growth of epitaxial layer with better quality on the other hand are provided. The light-emitting layer structure provided is located between the n-type GaN contact layer and the p-type GaN contact layer. Sequentially stacked on top of the n-type GaN contact layer in the following order, the light-emitting layer contains a lower barrier layer, at least one intermediate layer, and an upper barrier layer. That is, the light-emitting layer contains at least one intermediate layer interposed between the upper and lower barrier layers. When there are multiple intermediate layers inside the light-emitting layer, there is an intermediate barrier layer interposed between every two immediately adjacent intermediate layers.

1 . A light-emitting layer structure of a gallium-nitride (GaN) based light emitting diode (LED), wherein said LED comprises a sapphire substrate and comprises, on one side of said substrate from bottom to top, a n-type GaN contact layer, a light-emitting layer covering a part of an upper surface of said n-type GaN contact layer; a p-type GaN contact layer covering said light-emitting layer, a positive electrode covering said p-type GaN contact layer, and a negative electrode covering another part of said upper surface of said n-type GaN contact layer not covered by said light-emitting layer, wherein said light-emitting layer, sequentially from bottom to top, comprises: 
 a lower barrier layer made of un-doped aluminum-gallium-indium-nitride (Al 1-x-y Ga x In y N, 0≦x,y≦1, x+y≦1);    at least an intermediate layer, wherein, when there are more than one said intermediate layer, said intermediate layers stack sequentially and an intermediate barrier layer made of un-doped Al 1-i-j Ga i In j N (0≦i,j≦1, i+j≦1) is interposed between every two immediately adjacent said intermediate layers; and    an upper barrier layer made of un-doped Al 1-p-q Ga p In q N (0≦p,q≦1, p+q≦1).    
     
     
         2 . The light-emitting layer structure of a GaN-based LED according to  claim 1 , wherein said intermediate layer comprises, from bottom to top, a first ultra-thin quantum-dot layer made of indium-nitride (InN) and a quantum-well layer made of un-doped Al 1-m-n Ga m In n N (0≦m,n≦ 1 , m+n≦1).  
     
     
         3 . The light-emitting layer structure of a GaN-based LED according to  claim 2 , wherein said intermediate layer further comprises a second ultra-thin quantum-dot layer made of InN on top of said quantum-well layer.  
     
     
         4 . The light-emitting layer structure of a GaN-based LED according to  claim 2 , wherein said upper, intermediate, and lower barrier layers all have a thickness between 5 Å and 300 Å, said first ultra-thin quantum-dot layer has a thickness between 2 Å and 30 Å, and said quantum-well layer has a thickness between 5 Å and 100 Å.  
     
     
         5 . The light-emitting layer structure of a GaN-based LED according to  claim 3 , wherein said upper, intermediate, and lower barrier layers all have a thickness between 5 Å and 300 Å, said first and said second ultra-thin quantum-dot layers all have a thickness between 2 Å and 30 Å, and said quantum-well layer has a thickness between 5 Å and 100 Å.  
     
     
         6 . The light-emitting layer structure of a GaN-based LED according to  claim 1 , wherein said intermediate layer comprises, from bottom to top, a first ultra-thin layer made of InN and a quantum-well layer made of un-doped Al 1-m-n Ga m In n N (0≦m,n≦1, m+n≦1).  
     
     
         7 . The light-emitting layer structure of a GaN-based LED according to  claim 6 , wherein said intermediate layer further comprises a second ultra-thin layer made of InN on top of said quantum-well layer.  
     
     
         8 . The light-emitting layer structure of a GaN-based LED according to  claim 6 , wherein said upper, intermediate, and lower barrier layers all have a thickness between 5 Å and 300 Å, said first ultra-thin layer has a thickness between 2 Å and 10 Å, and said quantum-well layer has a thickness between 5 Å and 100 Å.  
     
     
         9 . The light-emitting layer structure of a GaN-based LED according to  claim 7 , wherein said upper, intermediate, and lower barrier layers all have a thickness between 5 Å and 300 Å, said first and said second ultra-thin layers all have a thickness between 2 Å and 10 Å, and said quantum-well layer has a thickness between 5 Å and 100 Å.  
     
     
         10 . The light-emitting layer structure of a GaN-based LED according to  claim 1 , wherein said intermediate layer is a super lattice well layer comprising at least a first ultra-thin monolayer made of InN and at least a second ultra-thin monolayer made of GaN, sequentially stacked and interleaved with each other.  
     
     
         11 . The light-emitting layer structure of a GaN-based LED according to  claim 10 , wherein said first ultra-thin monolayers and said second ultra-thin monolayers have identical number of layers, no more than five layers respectively, and a thickness between 2 Å and 20 Å for each individual layer.  
     
     
         12 . The light-emitting layer structure of a GaN-based LED according to  claim 10 , wherein said upper, intermediate, and lower barrier layers all have a thickness between 5 Å and 300 Å.  
     
     
         13 . A light-emitting layer structure of a GaN-based LED, wherein said LED comprises a sapphire substrate and comprises, on one side of said substrate from bottom to top, a n-type GaN contact layer, a light-emitting layer covering a part of an upper surface of said n-type GaN contact layer, a p-type GaN contact layer covering said light-emitting layer, a positive electrode covering said p-type GaN contact layer, and a negative electrode covering another part of said upper surface of said n-type GaN contact layer not covered by said light-emitting layer, wherein said light-emitting layer, sequentially from bottom to top, comprises: 
 a lower barrier layer, wherein said lower barrier layer is a super lattice barrier layer comprising at least a fifth ultra-thin monolayer made of AlN and at least a sixth ultra-thin monolayer made of GaN, sequentially stacked and interleaved with each other;    at least an intermediate layer, wherein, when there are more than one said intermediate layer, said intermediate layers stack sequentially and an intermediate barrier layer, being a super lattice barrier layer comprising at least a seventh ultra-thin monolayer made of In-doped AlN and at least a eighth ultra-thin monolayer made of In-doped GaN sequentially stacked and interleaved with each other, is interposed between every two immediately adjacent said intermediate layers; and    an upper barrier layer, wherein said upper barrier layer is a super lattice barrier layer comprising at least a ninth ultra-thin monolayer made of AlN and at least a tenth ultra-thin monolayer made of GaN, sequentially stacked and interleaved with each other.    
     
     
         14 . The light-emitting layer structure of a GaN-based LED according to  claim 13 , wherein said intermediate layer is a super lattice well layer comprising at least a third ultra-thin monolayer made of InN and at least a fourth ultra-thin monolayer made of GaN, sequentially stacked and interleaved with each other.  
     
     
         15 . The light-emitting layer structure of a GaN-based LED according to  claim 13 , wherein said upper, intermediate, and lower barrier layers all have a thickness between 5 Å and 300 Å.  
     
     
         16 . The light-emitting layer structure of a GaN-based LED according to  claim 14 , wherein said third ultra-thin monolayers and said fourth ultra-thin monolayers have identical number of layers, no more than five layers respectively, and a thickness between 2 Å and 20 Å for each individual layer.  
     
     
         17 . The light-emitting layer structure of a GaN-based LED according to  claim 13 , wherein said fifth ultra-thin monolayers and said sixth ultra-thin monolayers have identical number of layers, no more than five layers respectively, and a thickness between 2 Å and 20 Å for each individual layer.  
     
     
         18 . The light-emitting layer structure of a GaN-based LED according to  claim 13 , wherein said seventh ultra-thin monolayers and said eighth ultra-thin monolayers have identical number of layers, no more than five layers respectively, and a thickness between 2 Å and 20 Å for each individual layer.  
     
     
         19 . The light-emitting layer structure of a GaN-based LED according to  claim 13 , wherein said ninth ultra-thin monolayers and said tenth ultra-thin monolayers have identical number of layers, no more than five layers respectively, and a thickness between 2 Å and 20 Å for each individual layer.