Light emitting devices having light coupling layers with recessed electrodes

Abstract

A light emitting device comprises a first layer of an n-type semiconductor material, a second layer of a p-type semiconductor material, and an active layer between the first layer and the second layer. A light coupling structure is disposed adjacent to one of the first layer and the second layer. In some cases, the light coupling structure is disposed adjacent to the first layer. An orifice formed in the light coupling structure extends to the first layer. An electrode formed in the orifice is in electrical communication with the first layer.

What is claimed is: 
     
         1 . A light emitting device comprising:
 a semiconductor layer;   a light coupling layer on the semiconductor layer; and   an electrode on the semiconductor layer,   wherein the light coupling layer comprises a first layer having a first refractive index and a second layer having a second refractive index, and wherein the light coupling layer comprises light coupling moieties.   
     
     
         2 . The light emitting device of  claim 1  wherein the electrode is in a cavity of the light coupling layer. 
     
     
         3 . The light emitting device of claim wherein the semiconductor layer comprises an n-type semiconductor layer, a p-type semiconductor layer, a Group III-V semiconductor layer, or an n-GaN semiconductor layer. 
     
     
         4 . The light emitting device of  claim 1  wherein the first layer comprises a semiconductor layer, an n-type or p-type semiconductor layer, a Group III-V semiconductor layer, an n-GaN semiconductor layer, a u-type GaN semiconductor layer, a p-GaN semiconductor layer, an aluminum-containing Group III-V semiconductor layer, an AlGaN semiconductor layer, or a portion of the semiconductor layer. 
     
     
         5 . The light emitting device of  claim 1  wherein the second layer comprises a Group III-V semiconductor layer, a gallium nitride semiconductor layer, a u-type GaN semiconductor layer, an aluminum-containing Group III-V semiconductor layer, an aluminum gallium nitride semiconductor layer, or an aluminum nitride semiconductor layer. 
     
     
         6 . The light emitting device of  claim 1  wherein the light coupling structure further comprises a third layer adjacent to the second layer. 
     
     
         7 . The light emitting device of  claim 6  wherein the third layer comprises a Group III-V semiconductor layer, an aluminum-containing Group III-V semiconductor layer, an AlGaN semiconductor layer, or an AlN semiconductor layer. 
     
     
         8 . The light emitting device of  claim 1  wherein the electrode comprises one or more of titanium, aluminum, nickel, platinum, gold, silver, rhodium, copper and chromium. 
     
     
         9 . The light emitting device of  claim 1  wherein the light coupling layer further comprises additional layers. 
     
     
         10 . The light emitting device of  claim 1  wherein the light coupling moieties comprise triangular cross-sections, square cross-sections, or rectangular cross-sections. 
     
     
         11 . The light emitting device of  claim 1  wherein the light coupling moieties comprise conical, pyramidal, or rod-like cross-sections. 
     
     
         12 . The light emitting device of  claim 1  further comprising an active layer below the semiconductor layer. 
     
     
         13 . The light emitting device of  claim 1  further comprising an additional semiconductor layer below the active layer. 
     
     
         14 . The light emitting device of  claim 1  wherein the light coupling layer comprises a corrugation between about 10 nm and 3 microns, or between about 100 nm and 2 microns, or between about 200 nm and 15 microns. 
     
     
         15 . The light emitting device of  claim 1  wherein the light coupling layer comprises a corrugation that is less than 0.5 microns. 
     
     
         16 . The not emitting device of  claim 1  wherein a contact between the electrode and the semiconductor layer comprises an ohmic contact. 
     
     
         17 . The light emitting device of  claim 2  wherein a floor of the cavity comprises a corrugation between about 1 nm and 500 nm, or between about 10 nm and 100 nm. 
     
     
         18 . The light emitting device of  claim 2  wherein a floor of the cavity comprises a corrugation of less than about 0.5 microns, 0.1 microns, or 0.01 microns. 
     
     
         19 . The light emitting device of  claim 2  wherein a floor of the cavity comprises a corrugation smaller than a corrugation of the light coupling layer. 
     
     
         20 . The light emitting device of  claim 1  wherein the first layer is closer to the semiconductor layer than the second layer and the second refractive index is less than the first refractive index.