Method for fabricating a nitride-based semiconductor light emitting device

Abstract

An exemplary method includes the following steps. First, a substrate is provided. Second, a nitride-based multi-layered structure is epitaxially grown on the substrate. The multi-layered structure includes a first-type layer, an active layer, and a second-type layer arranged one on the other in that order along a direction away from the substrate. A crystal growth orientation of the multi-layered structure intersects with a <0001> crystal orientation thereof. Thirdly, the multi-layered structure is patterned to form a mesa structure thereof, wherein the first-type layer is partially exposed to form an exposed portion. The mesa structure has a top surface facing away from the substrate, and side surfaces adjacent to the top surface. Fourthly, a first-type electrode and a second-type electrode are formed in ohmic contact with the first-type layer and the second-type layer, respectively. Finally, the top and side surfaces of the patterned multi-layered structure are wet etched.

1 . A method for fabricating a nitride-based semiconductor light emitting device, the method comprising:
 providing a substrate;   epitaxially growing a nitride-based multi-layered structure on the substrate, the multi-layered structure comprising a first-type layer, an active layer and a second-type layer arranged in that order along a direction away from the substrate, wherein a crystal growth orientation of the multi-layered structure intersects with a <0001> crystal orientation of the multi-layered structure;   patterning the multi-layered structure to form a mesa structure thereof, wherein the first-type layer is partially exposed to form an exposed portion, and the mesa structure has a top surface facing away from the substrate and a plurality of side surfaces adjacent to the top surface;   forming a first-type electrode and a second-type electrode on the exposed portion and the top surface, respectively, wherein the first-type electrode is in ohmic contact with the first-type layer and the second-type electrode is in ohmic contact with the second-type layer; and   wet etching the patterned multi-layered structure to roughen the top surface and the side surfaces of the mesa structure.   
   
   
       2 . The method of  claim 1 , wherein the substrate is a single crystal plate, the single crystal plate has a crystal face on which the multi-layered is epitaxially grown, and the crystal growth orientation of the multi-layered structure matches a crystal orientation of the crystal face. 
   
   
       3 . The method of  claim 1 , wherein the first-type layer, the active layer and the second-type layer are made from one or more group III-nitride compound materials. 
   
   
       4 . The method of  claim 3 , further comprising irradiating the mesa structure with electromagnetic waves during the wet etching, wherein an energy of the electromagnetic waves is equal to or higher than an energy gap of at least one group III-nitride compound material which is etched. 
   
   
       5 . The method of  claim 1 , wherein the crystal growth orientation of the multi-layered structure is substantially perpendicular to the <0001> crystal orientation of the multi-layered structure. 
   
   
       6 . The method of  claim 1 , wherein the wet etching is performed by one of an acid etching solution containing phosphoric acid and sulfuric acid, and an alkaline etching solution containing potassium hydroxide. 
   
   
       7 . The method of  claim 1 , wherein an etching temperature during the wet etching is higher than 150 degrees Celsius. 
   
   
       8 . A method for fabricating a nitride-based semiconductor light emitting device, the method comprising:
 providing a single crystal substrate having a crystal face, wherein the crystal face is one of a non-polar face and a semi-polar face;   epitaxially growing a nitride-based multi-layered structure on the crystal face, wherein a crystal growth orientation of the multi-layered structure matches a crystal orientation of the crystal face, and the multi-layered structure includes an N-type layer and a P-type layer;   treating the multi-layered structure to form a mesa structure thereof;   forming a pair of electrodes on the multi-layered structure, the electrodes being electrically connected with the N-type layer and the P-type layer, respectively; and   wet etching the multi-layered structure to roughen at least one surface selected from the group consisting of a top surface and side surfaces of the mesa structure.   
   
   
       9 . The method of  claim 8 , further comprising irradiating the mesa structure with electromagnetic waves during the wet etching, wherein the multi-layered structure is made from one or more group III-nitride compound materials, and an energy of the electromagnetic waves is equal to or higher than an energy gap of at least one group III-nitride compound material which is etched. 
   
   
       10 . The method of  claim 8 , wherein the top surface faces away from the single crystal substrate, the side surfaces are adjacent to the top surface, and the top surface and all the side surfaces are roughened during the wet etching.