Semiconductor light emitting element, semiconductor light emitting device, and method for fabricating semiconductor light emitting element

Abstract

Projections/depressions forming a two-dimensional periodic structure are formed in a surface of a semiconductor multilayer film opposing the principal surface thereof, while a metal electrode with a high reflectivity is formed on the other surface. By using the diffracting effect of the two-dimensional periodic structure, the efficiency of light extraction from the surface formed with the projections/depressions can be improved. By reflecting light emitted toward the metal electrode to the surface formed with the projections/depressions by using the metal electrode with the high reflectivity, the foregoing effect achieved by the two-dimensional periodic structure can be multiplied.

1 - 20 . (canceled)  
   
   
       21 . A method for fabricating a semiconductor light emitting element, the method comprising the steps of: 
 (a) forming a first two-dimensional periodic structure in a principal surface of a substrate or in a principal surface of a semiconductor layer provided on the substrate; and    (b) successively forming a first semiconductor layer, an active layer, and a second semiconductor layer over the first two-dimensional periodic structure.    
   
   
       22 . The method of  claim 21 , wherein the step (b) includes the step of forming, in a back surface of the first semiconductor layer, a second two-dimensional periodic structure which is complementary to the first two-dimensional periodic structure by forming the first semiconductor layer in such a manner that the first two-dimensional periodic structure is filled therewith.  
   
   
       23 . The method of  claim 22 , further comprising the step of: 
 (c) after the step (b), removing the substrate or the substrate and the semiconductor layer to expose the second two-dimensional periodic structure.    
   
   
       24 . The method of  claim 23 , wherein the step (c) is performed by polishing the substrate and by wet etching.  
   
   
       25 . The method of  claim 23 , wherein the step (c) is performed by a laser lift-off process.  
   
   
       26 . The method of  claim 23 , wherein the substrate removed in the step (c) is reusable.  
   
   
       27 . The method of  claim 21 , further comprising the step of: 
 after the step (b), forming a high-reflection film composed of a metal film containing at least one of an Au film, a Pt film, a Cu film, an Ag film, an Al film, and a Rh film on a principal surface of the second semiconductor layer.    
   
   
       28 . The method of  claim 23 , further comprising the step of: 
 after the step (c), performing wet etching under a condition where an etching speed differs depending on a crystal plane to form the second two-dimensional periodic structure composed of projections or depressions each configured as a polygonal pyramid.    
   
   
       29 . The method of  claim 21 , wherein the step (b) includes the step of forming the first semiconductor layer in such a manner as to form a cavity in the first two-dimensional periodic structure.  
   
   
       30 . The method of  claim 21 , wherein the first two-dimensional periodic structure is composed of a structure made of at least any one of an oxide, a nitride, and a metal.  
   
   
       31 . The method of  claim 23 , wherein the second two-dimensional periodic structure is composed of depressions, the method further comprising the step of: 
 after the steps (b) and (c), increasing a depth of each of the depressions or changing a cross-sectional configuration of each of the depressions by allowing electricity to flow in the semiconductor light-emitting element in an electrolytic solution.    
   
   
       32 . The method of  claim 21 , wherein the step (a) includes the steps of: 
 (a1) coating a first resist on the principal surface of the substrate or of the semiconductor layer;    (a2) pressing, against the first resist, a mold formed with a two-dimensional periodic structure which is complementary to the first two-dimensional periodic structure to transfer a pattern which is homologous to the first two-dimensional periodic structure thereto; and    (a3) forming the first two-dimensional periodic structure by using, as a mask, the first resist to which the pattern homologous to the first two-dimensional periodic structure has been transferred.    
   
   
       33 . The method of  claim 21 , wherein the first two-dimensional periodic structure is composed of a resin provided on the substrate, the method further comprising the steps of: 
 (d) after the step (b), removing the substrate;    (e) coating a second resist on a back surface of the first semiconductor layer;    (f) placing the substrate formed with the first two-dimensional periodic structure on the second resist to transfer a pattern which is complementary to the first two-dimensional periodic structure to the second resist; and    (g) forming a second two-dimensional periodic structure which is complementary to the first two-dimensional periodic structure in a back surface of the first semiconductor layer by using, as a mask, the second resist to which the pattern complementary to the first two-dimensional periodic structure has been transferred.    
   
   
       34 . The method of  claim 21 , further comprising the steps of: 
 mounting the semiconductor light emitting element on a mounting substrate; and    molding the semiconductor light emitting element with a hemispherical resin by using a mold die formed with a hemispherical cavity.