Methods and devices for light extraction from a group iii-nitride volumetric led using surface and sidewall roughening

Abstract

A method of fabricating LEDs from a wafer comprising a substrate and epitaxial layers and having a substrate side and a epitaxial side, said method comprising: (a) applying a laser beam across at least one of said substrate side or said epitaxial side of said wafer to define at least one laser-scribed recess having a laser-machined surface; and (b) singulating said wafer along said laser-scribed recess to form singulated LEDs, said singulated LEDs having a top surface, a bottom surface, and a plurality of sidewalls, at least one of said sidewalls comprising at least a first portion comprising at least a portion of said laser-machined surface.

What is claimed is: 
     
         1 . A method of fabricating LEDs from a wafer comprising a substrate and epitaxial layers and having a substrate side and a epitaxial side, said method comprising:
 applying a laser beam across at least one of said substrate side or said epitaxial side of said wafer to define at least one laser-scribed recess having a laser-machined surface; and   singulating said wafer along said laser-scribed recess to form singulated LEDs, said singulated LEDs having a top surface, a bottom surface, and a plurality of sidewalls, at least one of said sidewalls comprising at least a first portion having a first texture and comprising at least a portion of said laser-machined surface, and a second portion having a second texture, wherein at least one of said first and second textures are different or said first and second portions are non-planar.   
     
     
         2 . The method of  claim 1 , wherein said second portion is orthogonal to said top surface. 
     
     
         3 . The method of  claim 2 , wherein first portion is defined along a non-crystallographic plane of said substrate, and second portion is defined along a crystallographic plane of said substrate. 
     
     
         4 . The method of  claim 1 , wherein said first texture comprises terraces and said second texture comprises vertical striations.