Inxalygazn optical emitters fabricated via substrate removal

Abstract

Devices and techniques for fabricating InAlGaN light-emitting devices are described that result from the removal of light-emitting layers from the sapphire growth substrate. In several embodiments, techniques for fabricating a vertical InAlGaN light-emitting diode structure that result in improved performance and or cost-effectiveness are described. Furthermore, metal bonding, substrate liftoff, and a novel RIE device separation technique are employed to efficiently produce vertical GaN LEDs on a substrate chosen for its thermal conductivity and ease of fabrication.

We claim:  
     
         1 . An InAlGaN light-emitting device comprising: 
 a host substrate;    an AlInGaN light-emitting structure, including device layers of a first and second polarity, proximate to a top side of the host substrate;    a first device contact to a top side of the AlInGaN light-emitting structure;    a wafer bonding layer, interposing the host substrate and the AlInGaN structure; and    a second device contact, positioned within the wafer bonding layer, electrically connected to a bottom side of the AlInGaN light-emitting structure.    
     
     
         2 . A device, as defined in    claim 1   , wherein the second device contact contains at least 50% silver.  
     
     
         3 . A device, as defined in    claim 1   , wherein the second device contact contains at least  50 % aluminum.  
     
     
         4 . A device, as defined in    claim 1   , wherein the host substrate is selected from a group that includes metals and semiconductors.  
     
     
         5 . A device, as defined in    claim 4   , wherein the host substrate is selected from a group that includes silicon, germanium, glass, copper, and gallium arsenide.  
     
     
         6 . A device, as defined in    claim 4   , wherein the host substrate is a semiconductor, further comprising a first substrate ohmic contact positioned on the top side of the host substrate.  
     
     
         7 . A device, as defined in    claim 6   , further comprising a second substrate ohmic contact that is electrically connected to a bottom side of the host substrate.  
     
     
         8 . A device, as defined in    claim 1   , further comprising a pair of polished mirrors positioned on two opposing side faces of the InAlGaN light-emitting structure forming an edge emitting laser.  
     
     
         9 . A device, as defined in    claim 1   , further comprising: 
 a first dielectric Bragg reflector mirror, positioned on the top side of the InAlGaN light-emitting structure; and    a second dielectric Bragg reflector mirror, positioned within the wafer bonding layer, adjacent to the bottom side of the InAlGaN light emitting structure.    
     
     
         10 . A method for fabricating a vertical conducting AlInGaN light-emitting device comprising the steps of: 
 growing an AlInGaN light-emitting structure that has device layers of a first and a second polarity on a growth substrate;    depositing a first ohmic metal layer onto an exposed side of the InAlGaN light-emitting structure;    depositing a second ohmic metal layer onto a host substrate; and    wafer bonding the first and second ohmic metal layers to form a first electrical contact within the wafer bond interface.    
     
     
         11 . A method, as defined in    claim 10   , wherein the first ohmic metal layer is selected from a group that includes silver, nickel, aluminum, gold, and cobalt.  
     
     
         12 . A method, as defined in    claim 10   , further comprising the steps of: 
 removing the growth substrate; and    fabricating a second electrical contact to a newly exposed side of InAlGaN light-emitting structure.    
     
     
         13 . A method, as defined in    claim 12   , further comprising the step of etching mesas through the AlInGaN light-emitting structure corresponding to a desired device size.  
     
     
         14 . A method, as defined in    claim 13   , further comprising the step of singulating the host substrate.  
     
     
         15 . A method, as defined in    claim 10   , wherein the step of growing an InAlGaN light-emitting structure comprises the step of growing an AlInGaN film having a thickness greater than 50 microns on the growth substrate.  
     
     
         16 . A method, as defined in    claim 10   , wherein the host substrate is selected from a group that includes metals and semiconductors.