Control of p-contact resistance in a semiconductor light emitting device

Abstract

A device according to embodiments of the invention includes a semiconductor structure including a light emitting layer disposed between an n-type region and a p-type region. A surface of the p-type region perpendicular to a growth direction of the semiconductor structure includes a first portion and a second portion. The first portion is less conductive than the second portion. The device further includes a p-contact formed on the p-type region. The p-contact includes a reflector and a blocking material. The blocking material is disposed over the first portion and no blocking material is disposed over the second portion.

What is claimed is: 
     
         1 . A method comprising:
 partially activating the p-type region in a III-nitride structure comprising a light emitting layer disposed between an n-type region and a p-type region;   after partially activating the p-type region, forming a metal p-contact on the p-type region, the metal p-contact comprising:
 a reflective first metal; and 
 a second metal; and 
   after forming the metal p-contact, further activating the p-type region.   
     
     
         2 . The method of  claim 1 , wherein the first metal is disposed between the second metal and the p-type region. 
     
     
         3 . The method of  claim 2 , wherein the metal p-contact further comprises a third metal and the first and second metals are disposed between the third metal and the p-type region. 
     
     
         4 . The method of  claim 3 , wherein the third metal is disposed above a first portion of the p-type region that is of lower conductivity. 
     
     
         5 . The method of  claim 3 , wherein the third metal prevents material disposed beneath the third metal from being oxidized. 
     
     
         6 . The method of  claim 3 , further comprising removing the second metal and the third metal by selective etch. 
     
     
         7 . The method of  claim 1 , wherein the first metal is embedded in the second metal. 
     
     
         8 . The method of  claim 7 , wherein the metal p-contact further comprises a third metal and the first and second metals are disposed between the third metal and the p-type region. 
     
     
         9 . The method of  claim 8 , wherein the third metal is disposed above a first portion of the p-type region that is of lower conductivity. 
     
     
         10 . The method of  claim 8 , wherein the third metal prevents material disposed beneath the third metal from being oxidized. 
     
     
         11 . The method of  claim 8 , further comprising removing the third metal by selective etch. 
     
     
         12 . A device comprising:
 a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region, wherein a surface of the p-type region comprises a first portion and a second portion, wherein the surface is perpendicular to a growth direction of the semiconductor structure, wherein the first portion is less conductive than the second portion; and   a p-contact formed on the p-type region, the p-contact comprising:
 a reflective first metal; and 
 a second metal, 
   the first metal being embedded in the second metal.   
     
     
         13 . The device of  claim 12 , wherein the metal p-contact further comprises a third metal and the first and second metals are disposed between the third metal and the p-type region. 
     
     
         14 . The device of  claim 13 , wherein the third metal is disposed above a first portion of the p-type region that is of lower conductivity. 
     
     
         15 . A device comprising:
 a semiconductor structure comprising a light emitting layer disposed between an n-type region and a p-type region, wherein a surface of the p-type region comprises a first portion and a second portion, wherein the surface is perpendicular to a growth direction of the semiconductor structure, wherein the first portion is less conductive than the second portion; and   a p-contact formed on the p-type region, the p-contact comprising:
 a reflective first metal; and 
 a second metal, 
   the first metal being disposed between the second metal and the p-type region.   
     
     
         16 . The device of  claim 15 , wherein the metal p-contact further comprises a third metal and the first and second metals are disposed between the third metal and the p-type region. 
     
     
         17 . The device of  claim 16 , wherein the third metal is disposed above a first portion of the p-type region that is of lower conductivity.