Nitride based semiconductor photo-luminescent device

Abstract

A nitride based semiconductor photo-luminescent device has an active layer having a quantum well structure. The active layer has both a high dislocation density region and a low dislocation density region that is lower in dislocation density than the high dislocation density region, wherein the low dislocation density region includes a current injection region into which a current is injected, and the active layer is less than 1×10 18 cm −3 in impurity concentration.

1 . A nitride based semiconductor photo-luminescent device having an active layer over a mask-less epitaxial lateral overgrowth substrate having a stripe-shaped nitride based semiconductor pattern with a window region, said active layer having both at least a high dislocation density region positioned over said stripe-shaped nitride based semiconductor pattern and at least a low dislocation density region positioned over said window region, and said low dislocation density region being lower in dislocation density than said high dislocation density region, 
 wherein said low dislocation density region includes a current injection region into which a current is injected, and said active layer is less than 1×10 18  cm −3  in impurity concentration.    
   
   
       2 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein a dislocation density of the low dislocation density region is not more than one tenth of a dislocation density of the high dislocation density region.  
   
   
       3 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein a dislocation density of the current injection region is not more than one tenth of an averaged dislocation density of the active layer.  
   
   
       4 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein a dislocation density of at least a part of the high dislocation density region is not less than 1×10 12  m −2 , and an average dislocation density of the current injection region in the low dislocation density region is less than 1×10 11  m −2 .  
   
   
       5 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein an average dislocation density of the active layer is not less than 1×10 12  m −2 , and an average dislocation density of the current injection region in the low dislocation density region is less than 1×10 11  m −2 .  
   
   
       6 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein an average dislocation density of the current injection region is less than 1×10 11  m −2 , and an average dislocation density of a peripheral region within a distance of 5 micrometers from the current injection region in the low dislocation density region is not less than 1×10 12  m −2 .  
   
   
       7 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein a current injection electrode is provided over an upper semiconductor layer overlying the active layer, and the active layer has an under-positioned region which is positioned under the current injection electrode, and an average dislocation density of the under-positioned region of the active layer is less than 1×10 11  m −2 , and an average dislocation density of a peripheral region within a distance of 5 micrometers from the under-positioned region is not less than 1×10 12  m −2 .  
   
   
       8 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein an average dislocation density of a peripheral region within a distance of 5 micrometers from the current injection region in the low dislocation density region is not more than one tenth of an average dislocation density of the current injection region.  
   
   
       9 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein a current injection electrode is provided over an upper semiconductor layer overlying the active layer, and the active layer has an under-positioned region which is positioned under the current injection electrode, and an average dislocation density of the under-positioned region of the active layer is not more than one tenth of an average dislocation density of an average dislocation density of a peripheral region within a distance of 5 micrometers from the under-positioned region.  
   
   
       10 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein a higher dislocation density region having a dislocation density of not less than ten times of a dislocation density of the current injection region is present in a peripheral region within a distance of 5 micrometers from the current injection region.  
   
   
       11 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein said window region has a width of not less than 25 micrometers.  
   
   
       12 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein said active layer is undoped.  
   
   
       13 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein said active layer comprises a multiple quantum well structure comprising alternating laminations of undoped quantum well layers and undoped potential barrier layers.  
   
   
       14 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein said active layer comprises a multiple quantum well structure comprising alternating laminations of undoped quantum well layers and Si-doped potential barrier layers having an impurity concentration of less than 1×10 18  cm −3 .  
   
   
       15 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein said active layer comprises a multiple quantum well structure comprising alternating laminations of Si-doped quantum well layers having an impurity concentration of less than 1×10 18  cm −3  and undoped potential barrier layers.  
   
   
       16 . The nitride based semiconductor photo-luminescent device as claimed in  claim 1 , wherein said active layer comprises a multiple quantum well structure comprising alternating laminations of Si-doped quantum well layers having an impurity concentration of less than 1×10 18  cm −3  and Si-doped potential barrier layers having an impurity concentration of less than 1×10 18  cm −3 .