Semiconductor light emitting device

Abstract

A semiconductor light emitting device including a substrate, an electrode and a light emitting region is provided. The substrate may have protruding portions formed in a repeating pattern on substantially an entire surface of the substrate while the rest of the surface may be substantially flat. The cross sections of the protruding portions taken along planes orthogonal to the surface of the substrate may be semi-circular in shape. The cross sections of the protruding portions may in alternative be convex in shape. A buffer layer and a GaN layer may be formed on the substrate.

What is claimed is: 
     
         1 . A C plane (0001) sapphire substrate comprising a plurality of protrusions formed on a primary surface of the sapphire substrate in a two-dimensionally repeated pattern so that in plan view of the sapphire substrate the protrusions have a shape of a polygon having sides that are not parallel to M-axis of the sapphire substrate. 
     
     
         2 . The sapphire substrate of  claim 1 , wherein the repeated pattern of the protrusions is such that six polygons surround one polygon to form a hexagon, and in plan view of the sapphire substrate the hexagon has sides that are perpendicular to A-axis of the sapphire substrate. 
     
     
         3 . The sapphire substrate of  claim 2 , wherein the polygon is a triangle. 
     
     
         4 . The sapphire substrate of  claim 3 , wherein the triangle is rounded. 
     
     
         5 . The sapphire substrate of  claim 3 , wherein in plan view of the sapphire substrate the triangle has sides that are perpendicular to M-axis of the sapphire substrate. 
     
     
         6 . The sapphire substrate of  claim 5 , wherein the triangle is rounded.