Resonant cavity III-nitride light emitting devices fabricated by growth substrate removal

Abstract

A semiconductor light emitting device includes an n-type region, a p-type region, and light emitting region disposed between the n- and p-type regions. The n-type, p-type, and light emitting regions form a cavity having a top surface and a bottom surface. Both the top surface and the bottom surface of the cavity may have a rough surface. For example, the surface may have a plurality of peaks separated by a plurality of valleys. In some embodiments, the thickness of the cavity is kept constant by incorporating an etch-stop layer into the device, then thinning the layers of the device by a process that terminates on the etch-stop layer.

1 . A method of forming a semiconductor light emitting device, the method comprising: 
 growing an epitaxial structure on a growth substrate, the epitaxial structure comprising: 
 an etch-stop layer; and  
 a stack of III-nitride epitaxial layers including a light emitting layer;  
 wherein the stack is grown over the etch-stop layer;  
   bonding a host substrate to the structure;    removing the growth substrate; and    thinning the structure by a process that terminates on the etch-stop layer.    
     
     
         2 . The method of  claim 1  wherein thinning comprises thinning by photoelectrochemical etching and the etch stop layer comprises AlGaN.  
     
     
         3 . The method of  claim 1  wherein thinning comprises thinning by photoelectrochemical etching and the etch stop layer comprises InGaN.  
     
     
         4 . The method of  claim 1  wherein a thickness of the structure after thinning is less than one micron.  
     
     
         5 . The method of  claim 1  wherein after thinning, a thickness of the structure at any point varies less than 5% from an average thickness.  
     
     
         6 . The method of  claim 1  wherein removing the growth substrate comprises etching away a sacrificial layer disposed between the growth substrate and an etch-stop layer.  
     
     
         7 . The method of  claim 6  wherein etching comprises etching by photoelectrochemical etching.  
     
     
         8 . The method of  claim 1  wherein: 
 the growth substrate comprises a layer of SiC and a layer of Si;    the stack is grown on the layer of SiC; and    removing the growth substrate comprises etching away the layer of Si.    
     
     
         9 . The method of  claim 8  wherein the growth substrate further comprises a layer of an oxide of silicon disposed between the layer of SiC and the layer of Si.  
     
     
         10 . The method of  claim 9  wherein removing the growth substrate comprises etching away the layer of Si and the layer of an oxide of silicon.  
     
     
         11 . The method of  claim 1  further comprising removing the etch-stop layer after thinning.