Group III-V nitride-based semiconductor substrate and method of making same

Abstract

A method of making a group III-V nitride-based semiconductor substrate has the steps of: providing a first crystal substrate; placing the first crystal substrate on a susceptor; holding down the first crystal substrate on the susceptor; and growing a first group III-V nitride-based semiconductor crystal on the first crystal substrate.

1 . A group III-V nitride-based semiconductor substrate, comprising: 
 a group III-V nitride-based semiconductor crystal;    wherein said substrate has a surface area of 45 cm 2  or more,    said substrate has thickness of 200 μm or more,    said substrate has an in-plane dislocation density of 2×10 7  cm −2  or less in average, and    the in-plane dislocation density is 150% or less of the average at maximum.    
   
   
       2 . The group III-V nitride-based semiconductor substrate according to  claim 1 , wherein: 
 said substrate has at a surface thereof a dispersion in crystal axis of ±0.3 degrees or less.    
   
   
       3 . The group III-V nitride-based semiconductor substrate according to  claim 1 , wherein: 
 said substrate has at an arbitrary point of a surface thereof a carrier concentration that falls within ±20% of an average carrier concentration at the surface.    
   
   
       4 . The group III-V nitride-based semiconductor substrate according to  claim 1 , wherein: 
 said substrate has at an arbitrary point of a surface thereof a thickness that falls within ±10 μm from an average thickness at the surface.    
   
   
       5 . The group III-V nitride-based semiconductor substrate according to  claim 1 , wherein; 
 said group III-V nitride-based semiconductor crystal has an FWHM value of X-ray rocking curve of 250 seconds or less.    
   
   
       6 . The group III-V nitride-based semiconductor substrate according to  claim 1 , wherein: 
 said group III-V nitride-based semiconductor crystal has a composition of In x Al y Ga 1-x-y N (x≧0, y≧0, x+y≦1)    
   
   
       7 . A method of making a group III-V nitride-based semiconductor substrate, comprising: 
 providing a first crystal substrate;    placing the first crystal substrate on a susceptor;    holding down the first crystal substrate on the susceptor; and    growing a first group III-V nitride-based semiconductor crystal on the first crystal substrate.    
   
   
       8 . The method according to  claim 7 , wherein: 
 the first crystal substrate is bonded to the susceptor.    
   
   
       9 . The method according to  claim 7 , wherein: 
 the first crystal substrate is a hetero-substrate that has a composition different from the first group III-V nitride-based semiconductor crystal.    
   
   
       10 . The method according to  claim 7 , wherein 
 the first crystal substrate is a hetero-substrate that has a composition different from the first group III-V nitride-based semiconductor crystal, and    said method further comprising;    growing a second group III-V nitride-based semiconductor crystal on the hetero-substrate,    providing the second group III-V nitride-based semiconductor crystal with a void;    growing a third group III-V nitride-based semiconductor crystal on the second group III-V nitride-based semiconductor crystal provided with the void;    removing the hetero-substrate and the second group III-V nitride-based semiconductor crystal to have the third group III-V nitride-based semiconductor crystal that corresponds to the first group III-V nitride-based semiconductor crystal.    
   
   
       11 . The method according to  claim 9 , wherein: 
 said hetero-substrate is a sapphire substrate.    
   
   
       12 . The method according to  claim 7 , wherein: 
 the first crystal substrate is a seed crystal substrate that has the same composition as the first group III-V nitride-based semiconductor crystal.    
   
   
       13 . The method according to  claim 7 , wherein: 
 said first group III-V nitride-based semiconductor crystal has a composition of In x Al y Ga 1-x-y N (x≧0, y≧0, x+y≦1).    
   
   
       14 . A method of making a group III-V nitride-based semiconductor substrate, comprising; 
 providing a first crystal substrate;    placing the first crystal substrate on a susceptor;    holding down the first crystal substrate on the susceptor to allow exposition of a part of an opposite surface of the first crystal substrate to a surface of the first crystal substrate that faces the susceptor; and    growing a first group III-V nitride-based semiconductor crystal on the exposed opposite surface of the first crystal substrate.    
   
   
       15 . The method according to  claim 14 , wherein: 
 the first crystal substrate is bonded to the susceptor.    
   
   
       16 . The method according to  claim 14 , wherein: 
 the first crystal substrate is a hetero-substrate that has a composition different from the first group III-V nitride-based semiconductor crystal.    
   
   
       17 . The method according to  claim 14 , wherein: 
 the first crystal substrate is a hetero-substrate that has a composition different from the first group III-V nitride-based semiconductor crystal, and    said method further comprising:    growing a second group III-V nitride-based semiconductor crystal on the hetero-substrate,    providing the second group III-V nitride-based semiconductor crystal with a void;    growing a third group III-V nitride-based semiconductor crystal on the second group III-V nitride-based semiconductor crystal provided with the void;    removing the hetero-substrate and the second group III-V nitride-based semiconductor crystal to have the third group III-V nitride-based semiconductor crystal that corresponds to the first group III-V nitride-based semiconductor crystal.    
   
   
       18 . The method according to  claim 16 , wherein: 
 said hetero-substrate is a sapphire substrate.    
   
   
       19 . The method according to  claim 14 , wherein: 
 the first crystal substrate is a seed crystal substrate that has the same composition as the first group III-V nitride-based semiconductor crystal.    
   
   
       20 . The method according to  claim 14 , wherein: 
 said first group III-V nitride-based semiconductor crystal has a composition of In x Al y Ga 1-x-y N (x≧0, y≧0, x+y≦1).