Semiconductor diode with suppression of auger generation processes

Abstract

A multi-layer Auger suppressed diode having at least two exclusion interfaces and at least two extraction interfaces. A specific embodiment has two composite contacts, each consisting of a heavily doped layer ( 3, 4 ) and a buffer layer ( 8, 9 ) of lower doped, high bandgap material sandwiched between the heavily doped layer and the active region ( 2 ) of the device.

What is claimed is:  
     
       1. A diode comprising multiple epitaxial layers of semiconducting material including: 
       a first outer layer ( 4 ) of heavily doped p-type material;  
       an active layer ( 2 ) of lightly doped semiconducting material; and  
       a second outer layer ( 3 ) of heavily doped n-type material,  
       characterised by the diode further comprising: 
       a first buffer layer ( 8 ) of lightly doped p-type material; and  
       a second buffer layer ( 9 ) of lightly doped n-type material;  
       the layers ( 2 ,  3 ,  4 ,  8 ,  9 ) being arranged in a stack with the first buffer layer ( 8 ) being sandwiched between the active layer ( 2 ) and the first outer layer ( 4 ) and forming, when a reverse bias is applied, an extracting interface with each, and the second buffer layer ( 9 ) being sandwiched between the active layer ( 2 ) and the second outer layer ( 3 ) and forming, when a reverse bias is applied, an excluding interface with each.  
     
     
       2. A diode according to  claim 1  wherein the active layer ( 2 ) is n-type material. 
     
     
       3. A diode according to  claim 1  wherein the active layer ( 2 ) is p-type material. 
     
     
       4. A diode according to  claim 1  wherein both the first buffer layer ( 8 ) and the second buffer layer ( 9 ) have doping concentrations that are close to or equal to the doping concentration in the active layer, the bandgaps of said active layer ( 2 ) and buffer layers ( 8 ,  9 ) being such that the minority carrier concentration in each of said buffer layers ( 8 ,  9 ) is less than one tenth of the minority carrier concentration in said active layer ( 2 ). 
     
     
       5. A diode according to  claim 1  wherein the doping concentration in the heavily doped material is greater than 2×10 17  cm −3 . 
     
     
       6. A diode according to  claim 1  wherein the doping concentration in the active layer is less than 5×10 16  cm −3 . 
     
     
       7. A diode according to  claim 1  wherein the semiconducting material is a cadmium mercury telluride compound having the formula Hg (1-x) Cd x Te wherein 0<x<1. 
     
     
       8. A diode according to  claim 1  wherein the transition between the heavily doped semiconducting material and the lightly doped semiconducting material takes place over a distance of several microns. 
     
     
       9. A diode according to  claim 1  wherein the thickness of the active layer ( 2 ) is less than or equal to the diffusion length of the minority carrier. 
     
     
       10. A diode according to  claim 9  wherein the thickness of the active layer ( 2 ) is less than 5 μm. 
     
     
       11. A diode according to  claim 10  wherein the thickness of the active layer ( 2 ) is less than 2 μm. 
     
     
       12. A diode according to  claim 1  wherein the diode further comprises a substrate ( 5 ) that is in contact with the one of the outer layers ( 3 ,  4 ). 
     
     
       13. A diode according to  claim 12  wherein the substrate ( 5 ) is in contact with the first outer layer ( 4 ). 
     
     
       14. A diode comprising multiple epitaxial layers of semiconducting material including: 
         a first outer layer of heavily doped p - type material;    
         an active layer of lightly doped p - type semiconducting material;    
         a second outer layer of heavily doped n - type material;    
         a first buffer layer of lightly doped p - type material; and    
         a second buffer layer of lightly doped n - type material;    
       
         wherein the layers are arranged in a stack with the first buffer layer being sandwiched between the active layer and the first outer layer and forming, when a reverse bias is applied, an excluding interface, and the second buffer layer being sandwiched between the active layer and the second outer layer and forming, when a reverse bias is applied, an extracting interface. 
       
     
     
       15. A diode according to  claim 14 , wherein both the first buffer layer and the second buffer layer having doping concentrations that are close to or equal to the doping concentration in the active layer, the bandgaps of the active layer and the buffer layers being such that the minority carrier concentration in each of the buffer layers is less than one tenth of the minority carrier concentration in the active layer. 
     
     
       16. A diode according to  claim 14 , wherein the doping concentration in the heavily doped material is greater than  2 × 10   17    cm   −3   .   
     
     
       17. A diode according to  claim 14 , wherein the doping concentration in the active layer is less than  5 × 10   16    cm   −3   .   
     
     
       18. A diode according to  claim 14 , wherein the semiconducting material is a cadmium mercury telluride compound having the formula Hg (1-x)   CD   x   Te wherein  0 <x< 1 .   
     
     
       19. A diode according to  claim 14 , wherein the transition between the heavily doped semiconducting material and the lightly doped semiconducting material takes place over a distance of several microns. 
     
     
       20. A diode according to  claim 14 , wherein the thickness of the active layer is less than or equal to the diffusion length of the minority carrier. 
     
     
       21. A diode according to  claim 20 , wherein the thickness of the active layer is less than  5  μm. 
     
     
       22. A diode according to  claim 21 , wherein the thickness of the active layer is less than  2  μm. 
     
     
       23. A diode according to  claim 14 , wherein the diode further comprises a substrate that is in contact with one of the outer layers. 
     
     
       24. A diode according to  claim 23 , wherein the substrate is in contact with the first outer layer. 
     
     
       25. A diode comprising multiple epitaxial layers of semiconducting material comprising: 
         a first outer layer of heavily doped p - type material;    
       
         an active layer of lightly doped semiconducting material;  
       
         a second outer layer of heavily doped n - type material;    
         a first buffer layer of lightly doped p - type material; and    
         a second buffer layer of lightly doped n - type material,    
       
         wherein the layers are arranged in a stack with the first buffer layer being sandwiched between the active layer and the first outer layer and the second buffer layer being sandwiched between the active layer and the second outer layer, and  
       
         when the active layer is n - type semiconducting material and a reverse bias is applied, the first buffer layer forms an extracting interface with both the active layer and the first outer layer and the second buffer layer forms an excluding interface with both the active layer and the second outer layer, and    
         when the active layer is p - type semiconducting material and a reverse bias is applied, the first buffer layer forms an excluding interface with both the active layer and the first outer layer and the second buffer layer forms an extracting interface with both the active layer and the second outer layer.   
     
     
       26. A diode according to  claim 25 , wherein the active layer is n- type material.   
     
     
       27. A diode according to  claim 25 , wherein the active layer is p- type material.   
     
     
       28. A diode according to  claim 25 , wherein both the first buffer layer have doping concentrations that are close to or equal to the doping concentration in the active layer, the bandgaps of said active layer and buffer layers being such that the minority carrier concentration in each of said buffer layers is less than one tenth of the minority carrier concentration in said active layer. 
     
     
       29. A diode according to  claim 25 , wherein the doping concentration in the heavily doped material is greater than  2 × 10   17    cm   −3   .   
     
     
       30. A diode according to  claim 25 , wherein the doping concentration in the active layer is less than  5 × 10   16    cm   −3   .   
     
     
       31. A diode according to  claim 25 , wherein the semiconducting material is a cadmium mercury telluride compound having the formula Hg (1-x)   CD   x   Te wherein  0 <x< 1 .   
     
     
       32. A diode according to  claim 25 , wherein the transition between the heavily doped semiconducting material and the lightly doped semiconducting material takes place over a distance of several microns. 
     
     
       33. A diode according to  claim 25 , wherein the thickness of the active layer is less than or equal to the diffusion length of the minority carrier. 
     
     
       34. A diode according to  claim 33 , wherein the thickness of the active layer is less than  5  μm. 
     
     
       35. A diode according to  claim 34 , wherein the thickness of the active layer is less than  2  μm. 
     
     
       36. A diode according to  claim 25 , wherein the diode further comprises a substrate that is in contact with the one of the outer layer. 
     
     
       37. A diode according to  claim 36 , wherein the substrate is in contact with the first outer layer.