Deep ultraviolet light emitting devices and methods of fabricating deep ultraviolet light emitting devices

Abstract

Light emitting devices and methods of fabricating light emitting devices that emit at wavelengths less than 360 nm with wall plug efficiencies of at least than 4% are provided. Wall plug efficiencies may be at least 5% or at least 6%. Light emitting devices and methods of fabricating light emitting devices that emit at wavelengths less than 345 nm with wall plug efficiencies of at least than 2% are also provided. Light emitting devices and methods of fabricating light emitting devices that emit at wavelengths less than 330 nm with wall plug efficiencies of at least than 0.4% are provided. Light emitting devices and methods of fabricating light emitting devices having a peak output wavelength of not greater than 360 nm and an output power of at least 5 mW, having a peak output wavelength of 345 nm or less and an output power of at least 3 mW and/or a peak output wavelength of 330 nm or less and an output power of at least 0.3 mW at a current density of less than about 0.35 μA/μm 2 are also provided. The semiconductor light emitting devices may have a direct current lifetime of at least 100 hours, at least 500 hours or at least 1000 hours.

1 . A semiconductor light emitting device having a peak output wavelength of not greater than 360 nm and a wall plug efficiency of at least 4%.  
     
     
         2 . The semiconductor light emitting device of  claim 1 , wherein the wall plug efficiency is at least 5%.  
     
     
         3 . The semiconductor light emitting device of  claim 1 , wherein the wall plug efficiency is at least 6%.  
     
     
         4 . The semiconductor light emitting device of  claim 1 , wherein the light emitting device has a direct current lifetime of at least 100 hours.  
     
     
         5 . The semiconductor light emitting device of  claim 1 , wherein the light emitting device has a direct current lifetime of at least 500 hours.  
     
     
         6 . The semiconductor light emitting device of  claim 1 , wherein the light emitting device has a direct current lifetime of at least 1000 hours.  
     
     
         7 . The semiconductor light emitting device of  claim 1 , wherein the light emitting device comprises an active region on a low defect density base structure.  
     
     
         8 . The semiconductor light emitting device of  claim 7 , wherein the low defect density base structure has a threading defect density less than 4×18 cm −2 .  
     
     
         9 . The semiconductor light emitting device of  claim 1 , wherein the wall plug efficiency is provided at a current density of less than about 0.35 μA/μm 2 .  
     
     
         10 . A semiconductor light emitting device having a peak output wavelength of less than 345 nm and a wall plug efficiency of at least 2%.  
     
     
         11 . The semiconductor light emitting device of  claim 10 , wherein the wall plug efficiency is at least 3%.  
     
     
         12 . The semiconductor light emitting device of  claim 10 , wherein the wall plug efficiency is at least 4%.  
     
     
         13 . The semiconductor light emitting device of  claim 10 , wherein the wall plug efficiency is provided at a current density of less than about 0.35 μA/μm 2 .  
     
     
         14 . The semiconductor light emitting device of  claim 10 , wherein the wall plug efficiency is at least 6% at a current density of less than about 0.08 μA/μm 2 .  
     
     
         15 . The semiconductor light emitting device of  claim 10 , wherein the light emitting device has a direct current lifetime of at least 100 hours.  
     
     
         16 . The semiconductor light emitting device of  claim 10 , wherein the light emitting device has a direct current lifetime of at least 500 hours.  
     
     
         17 . The semiconductor light emitting device of  claim 10 , wherein the light emitting device has a direct current lifetime of at least 1000 hours.  
     
     
         18 . The semiconductor light emitting device of  claim 10 , wherein the light emitting device comprises an active region on a low defect density base structure.  
     
     
         19 . The semiconductor light emitting device of  claim 18 , wherein the low defect density base structure has a threading defect density less than 4×10 8 cm   −2 .  
     
     
         20 . A semiconductor light emitting device having a peak output wavelength of less than 330 nm and a wall plug efficiency of at least 0.4%.  
     
     
         21 . The semiconductor light emitting device of  claim 20 , wherein the wall plug efficiency is provided at a current density of less than about 0.35 μA/μm 2 .  
     
     
         22 . The semiconductor light emitting device of  claim 20 , wherein the light emitting device has a direct current lifetime of at least 100 hours.  
     
     
         23 . The semiconductor light emitting device of  claim 20 , wherein the light emitting device has a direct current lifetime of at least 500 hours.  
     
     
         24 . The semiconductor light emitting device of  claim 20 , wherein the light emitting device has a direct current lifetime of at least 1000 hours.  
     
     
         25 . The semiconductor light emitting device of  claim 20 , wherein the light emitting device comprises an active region on a low defect density base structure.  
     
     
         26 . The semiconductor light emitting device of  claim 25 , wherein the low defect density base structure has a threading defect density less than 4×10 8  cm −2 .  
     
     
         27 . A light emitting device having a peak output wavelength of not greater than 360 nm and a direct current lifetime of at least 100 hours.  
     
     
         28 . The semiconductor light emitting device of  claim 27 , wherein the light emitting device has a direct current lifetime of at least 500 hours.  
     
     
         29 . The semiconductor light emitting device of  claim 27 , wherein the light emitting device has a direct current lifetime of at least 1000 hours.  
     
     
         30 . The semiconductor light emitting device of  claim 27 , wherein the light emitting device comprises an active region on a low defect density base structure.  
     
     
         31 . The semiconductor light emitting device of  claim 30 , wherein the low defect density base structure has a threading defect density less than 4×10 8  cm −2 .  
     
     
         32 . The semiconductor light emitting device of  claim 27 , wherein the peak output wavelength is 345 nm or less.  
     
     
         33 . The semiconductor light emitting device of  claim 32 , wherein the light emitting device has a direct current lifetime of at least 500 hours.  
     
     
         34 . The semiconductor light emitting device of  claim 32 , wherein the light emitting device has a direct current lifetime of at least 1000 hours.  
     
     
         35 . The semiconductor light emitting device of  claim 32 , wherein the light emitting device comprises an active region on a low defect density base structure.  
     
     
         36 . The semiconductor light emitting device of  claim 35 , wherein the low defect density base structure has a threading defect density less than 4×10 8  cm −2 .  
     
     
         37 . The semiconductor light emitting device of  claim 27 , wherein the peak output wavelength is 330 nm or less.  
     
     
         38 . The semiconductor light emitting device of  claim 37 , wherein the light emitting device has a direct current lifetime of at least 500 hours.  
     
     
         39 . The semiconductor light emitting device of  claim 37 , wherein the light emitting device has a direct current lifetime of at least 1000 hours.  
     
     
         40 . The semiconductor light emitting device of  claim 37 , wherein the light emitting device comprises an active region on a low defect density base structure.  
     
     
         41 . The semiconductor light emitting device of  claim 40 , wherein the low defect density base structure has a threading defect density less than 4×10 8  cm −2 .  
     
     
         42 . A semiconductor light emitting device having a peak output wavelength of not greater than 360 nm and an output power of at least 5 mW at a current density of less than about 0.35 μA/μm 2 .  
     
     
         43 . A semiconductor light emitting device having a peak output wavelength of 345 nm or less and an output power of at least 3 mW at a current density of less than about 0.35 μA/μm 2 .  
     
     
         44 . A semiconductor light emitting device having a peak output wavelength of 330 nm or less and an output power of at least 0.3 mW at a current density of less than about 0.35 A/μm 2 .  
     
     
         45 . A light emitting device, comprising: 
 a low defect density base structure comprising: 
 an n-type SiC substrate; and  
 a GaN layer doped with n-type dopants;  
   a quantum well active region on the low defect density base structure that emits light at a peak output wavelength of not greater than 360 nm, the quantum well active region comprising: 
 a well layer comprising GaN or AlGaN; and  
 a doped AlGaN barrier layer;  
   an AlGaN layer on the quantum well active region; and    a GaN based contact layer on the AlGaN layer.    
     
     
         46 . The light emitting device of  claim 45 , wherein the GaN layer doped with n-type dopants comprises a doped GaN layer having a defect density of less than about 4×10 8  cm −2 .  
     
     
         47 . The light emitting device of  claim 45 , wherein the GaN layer doped with n-type dopants comprises GaN doped with silicon.  
     
     
         48 . The light emitting device of  claim 45 , wherein the AlGaN layer on the quantum well active region comprises an AlGaN layer doped with a p-type dopant on the quantum well active region and the GaN based contact layer on the AlGaN layer comprises a GaN based contact layer doped with a p-type dopant.  
     
     
         49 . The light emitting device of  claim 48 , wherein the p-type dopant comprises Mg.  
     
     
         50 . The light emitting device of  claim 45 , wherein the barrier layer is doped with Si.  
     
     
         51 . The light emitting device of  claim 45 , wherein the quantum well active region comprises ten quantum well layers and eleven barrier layers with the quantum well layers being disposed between adjacent barrier layers.  
     
     
         52 . The light emitting device of  claim 45 , wherein the light emitting device has an overall thickness of less than about 2.5 μm.  
     
     
         53 . A light emitting device, comprising: 
 a quantum well active region configured to emit at a peak output wavelength of not greater than 360 nm and comprising: 
 a barrier layer comprising Al w In x Ga 1-x-w N, where 0<w≦1, 0≦x<1 and 0<w+x≦1 and where w and x provide a barrier energy greater than a bandgap energy of GaN or within about 1 eV of the bandgap energy of GaN; and  
 a well layer comprising Al y In z Ga 1-y-z N on the barrier layer, where 0≦y<1,0≦z<1 and 0≦y+z<1.  
   
     
     
         54 . The light emitting device of  claim 53 , further comprising: 
 a first layer of Al p Ga 1-p N doped with a p-type dopant on the quantum well active region where 0<p≦0.8; and    a second layer of Al q Ga 1-q N doped with a p-type dopant on the first layer, where 0≦q<p.    
     
     
         55 . The light emitting device of  claim 53 , further comprising a GaN layer doped with an n-type dopant and having a threading dislocation density of not greater than 4×10 8  cm −2 , the quantum well active region being disposed on the GaN layer doped with an n-type dopant.  
     
     
         56 . The light emitting device of  claim 53 , further comprising a semiconductor substrate and wherein the quantum well active region is disposed on the semiconductor substrate.  
     
     
         57 . The light emitting device of  claim 56 , wherein the semiconductor substrate comprises a conducting substrate.  
     
     
         58 . The light emitting device of  claim 56 , wherein the semiconductor substrate comprises a SiC substrate.  
     
     
         59 . The light emitting device of  claim 56 , wherein the semiconductor substrate comprises an insulating substrate.  
     
     
         60 . The light emitting device of  claim 56 , wherein the semiconductor substrate comprises a sapphire substrate.  
     
     
         61 . The light emitting device of  claim 56 , wherein the semiconductor substrate comprises a GaN substrate.  
     
     
         62 . The light emitting device of  claim 53 , wherein the barrier layer is doped with an n-type dopant.  
     
     
         63 . The light emitting device of  claim 54 , wherein the barrier layer has a thickness of from about 10 Å to about 100 Å and the well layer has a thickness of from about 10 Å to about 30 Å.  
     
     
         64 . The light emitting device of  claim 63 , wherein the first layer has a thickness of about 50 Å and the second layer has a thickness of about 300 Å.  
     
     
         65 . The light emitting device of  claim 54 , wherein the barrier layer comprises Al w In x Ga 1-x-w N, where 0.2<w≦0.8, 0≦x<0.2 and 0.2<w+x≦1 and has a thickness of from about 10 Å to about 60 Å; 
 the well layer comprises Al y In z Ga 1-y-z N on the barrier layer, where 0≦y<0.4, 0≦z<0.1 and 0≦y+z<0.5 and has a thickness of from about 10 Å to about 30 Å;    the first layer comprises Al p Ga 1-p N doped with a p-type dopant on the quantum well active region where 0.3<p≦0.8 and has a thickness of from about 50 Å to about 250 Å;    the second layer comprises Al q Ga 1-q N doped with a p-type dopant on the first layer, where 0≦q<p and the second layer has a thickness of from about 200 Å to about 600 Å; and    wherein the quantum well active region comprises from about 3 to about 12 quantum wells of the well layer and corresponding barrier layers.    
     
     
         66 . The light emitting device of  claim 54 , wherein the barrier layer comprises Al w In x Ga 1-x-w N, where 0.2<w≦0.8, 0≦x<0.2 and 0.2<w+x≦1 and has a thickness of from about 10 Å to about 60 Å; 
 the well layer comprises Al y In z Ga 1-y-z N on the barrier layer, where y-0 and z=0 and has a thickness of from about 10 Å to about 30 Å;    the first layer comprises Al p Ga 1-p N doped with a p-type dopant on the quantum well active region where 0.3<p≦0.8 and has a thickness of from about 50 Å to about 250 Å;    the second layer comprises Al q Ga 1-q N doped with a p-type dopant on the first layer, where 0≦q<p and the second layer has a thickness of from about 200 Å to about 600 Å;    wherein the quantum well active region comprises from about 3 to about 12 quantum wells of the well layer and corresponding barrier layers; and    wherein a peak output wavelength of the light emitting device is not greater than 345 nm.    
     
     
         67 . The light emitting device of  claim 54 , wherein the barrier layer comprises Al w In x Ga 1-x-w N, where 0.3<w≦0.8, 0≦x<0.2 and 0.3<w+x≦1 and has a thickness of from about 10 Å to about 50 Å; 
 the well layer comprises Al y In z Ga 1-y-z N on the barrier layer, where 0≦y<0.4, 0≦z<0.1 and 0≦y+z<0.5 and has a thickness of from about 10 Å to about 30 Å;    the first layer comprises Al p Ga 1-p N doped with a p-type dopant on the quantum well active region where 0.3<p≦0.8 and has a thickness of from about 50 Å to about 250 Å;    the second layer comprises Al q Ga 1-q N doped with a p-type dopant on the first layer, where 0≦q<p and the second layer has a thickness of from about 200 Å to about 600 Å;    wherein the quantum well active region comprises from about 3 to about 12 quantum wells of the well layer and corresponding barrier layers; and    wherein a peak output wavelength of the light emitting device is not greater than 330 nm.    
     
     
         68 . The light emitting device of  claim 54 , wherein the well layer comprises Al w In x Ga 1-x-w N, where w=0, x=0 and has a thickness of 15 Å; 
 the barrier layer comprises Al y In z Ga 1-y-z N doped with silicon on the barrier layer, where y=0.3, z=0 and has a thickness of 35 Å;    the first layer comprises Al p Ga 1-p N doped with Mg on the quantum well active region where p=0.5 and has a thickness of 50 Å;    the second layer comprises Al q Ga 1-q N doped with Mg on the first layer, where q=0 and the second layer has a thickness of 300 Å;    wherein the quantum well active region comprises ten quantum wells of the well layer and corresponding barrier layers; and    wherein a peak output wavelength of the light emitting device is about 340 nm.    
     
     
         69 . The light emitting device of  claim 54 , wherein the well layer comprises Al w In x Ga 1-x-w N where w=0.3, x=0 and has a thickness of 15 Å; 
 the barrier layer comprises Al y In z Ga 1-y-z N doped with silicon on the barrier layer, where y=0.5, z=0 and has a thickness of 20 Å;    the first layer comprises Al p Ga 1-p N doped with Mg on the quantum well active region where p=0.5 and has a thickness of 230 Å;    the second layer comprises Al q Ga 1-q N doped with Mg on the first layer, where q=0 and the second layer has a thickness of 300 Å;    wherein the quantum well active region comprises ten quantum wells of the well layer and corresponding barrier layers; and    wherein a peak output wavelength of the light emitting device is about 325 nm.    
     
     
         70 . A method of fabricating light emitting device, comprising: 
 forming a quantum well active region configured to emit at a peak output wavelength of not greater than 360 nm and comprising: 
 a barrier layer comprising Al w In x Ga 1-x-w N, where 0<w≦1, 0≦x<1 and 0<w+x≦1 and where w and x provide a barrier energy greater than a bandgap energy of GaN or within about 1 eV of the bandgap energy of GaN; and  
 a well layer comprising Al y In z Ga 1-y-z N on the barrier layer, where 0≦y<1, 0≦z<1 and 0≦y+z<1.  
   
     
     
         71 . The method of  claim 70 , further comprising: 
 forming a first layer of Al p Ga 1-p N doped with a p-type dopant on the quantum well active region where 0<p≦0.8; and    forming a second layer of Al q Ga 1-q N doped with a p-type dopant on the first layer, where 0≦q<p.    
     
     
         72 . The method of  claim 70 , further comprising forming a GaN layer doped with an n-type dopant and having a threading dislocation density of not greater than 4×10 8  cm −2  and wherein forming a quantum well active region comprises forming a quantum well active region on the GaN layer doped with an n-type dopant.  
     
     
         73 . The method of  claim 70 , wherein forming a quantum well active region comprises forming a quantum well active region on a semiconductor substrate.  
     
     
         74 . The method of  claim 73 , wherein the semiconductor substrate comprises a conducting substrate.  
     
     
         75 . The method of  claim 73 , wherein the semiconductor substrate comprises a SiC substrate.  
     
     
         76 . The method of  claim 73 , wherein the semiconductor substrate comprises an insulating substrate.  
     
     
         77 . The method of  claim 73 , wherein the semiconductor substrate comprises a sapphire substrate.  
     
     
         78 . The method of  claim 73 , wherein the semiconductor substrate comprises a GaN substrate.  
     
     
         79 . A method of fabricating a light emitting device, comprising: 
 forming a low defect density base structure comprising: 
 an n-type SiC substrate; and  
 a GaN layer doped with n-type dopants;  
   forming a quantum well active region on the low defect density base structure that emits light at a peak output wavelength of not greater than 360 nm, the quantum well active region comprising: 
 a well layer comprising GaN or AlGaN; and  
 a doped AlGaN barrier layer;  
   forming an AlGaN layer on the quantum well active region; and    forming a GaN based contact layer on the AlGaN layer.    
     
     
         80 . A method of fabricating a semiconductor light emitting device comprising forming a light emitting device having a peak output wavelength of not greater than 360 nm and a wall plug efficiency of at least 4%.  
     
     
         81 . A method of fabricating a semiconductor light emitting device comprising forming a light emitting device having a peak output wavelength of 345 nm or less and a wall plug efficiency of at least 2%.  
     
     
         82 . A method of fabricating a semiconductor light emitting device comprising forming a light emitting device having a peak output wavelength of 330 nm or less and a wall plug efficiency of at least 0.4%.  
     
     
         83 . A method of fabricating a semiconductor light emitting device comprising forming a light emitting device having a peak output wavelength of not greater than 360 nm and a direct current lifetime of at least 100 hours.  
     
     
         84 . A method of fabricating a semiconductor light emitting device comprising forming a light emitting device having a peak output wavelength of not greater than 360 nm and an output power of at least 3 mW at a current density of about 0.35 μA/μM 2 .