Semiconductor device and semiconductor substrate, and method of fabricating the same

Abstract

A substrate includes: a crystalline substrate including a primary surface and a crystal plane provided within the primary surface so as to have a surface orientation different from a surface orientation of the primary surface; a semiconductor layered structure grown over the crystalline substrate; and an active region provided at a portion in the semiconductor layer structure above the crystal plane.

1 . A substrate comprising: 
 a crystalline substrate including a primary surface so as to have a stepped portion;    a III-Nitride semiconductor layered structure grown over the crystalline substrate, wherein the semiconductor layered structure has a high defect region provided by concentrating lattice defects extending toward a tilted direction of the stepped portion and a low defect region in the vicinity of the high defect region; and    an active region provided at a portion of the low defect region.    
   
   
       2 . A substrate according to  claim 1 , wherein the portion in the semiconductor layered structure at which the active region is provided contains fewer defects as compared to surrounding regions.  
   
   
       3 . A substrate according to  claim 1 , wherein the crystal plane is a tilted surface which is tilted with respect to the primary surface of the crystalline substrate, and the active region is positioned above lattice defects which extend in a direction substantially perpendicular to the crystal plane.  
   
   
       4 . A substrate according to  claim 1 , wherein a convex-and-concave structure is provided in the primary surface of the crystalline substrate, and the crystal plane is part of the convex-and-concave structure.  
   
   
       5 . A substrate according to  claim 4 , wherein a convex portion included in the convex-and-concave structure has a forward mesa structure.  
   
   
       6 . A substrate according to  claim 4 , wherein a convex portion included in the convex-and-concave structure has a cross section in the shape of a triangle pointing upward from the primary surface of the crystalline substrate.  
   
   
       7 . A substrate according to  claim 4 , wherein the convex-and-concave structure has a periodic structure.  
   
   
       8 . A substrate according to  claim 1 , wherein the active region is made of a III group nitride compound material, and serves as a light emitting region of a light emitting element.  
   
   
       9 . A substrate according to  claim 1 , wherein the active region is made of a III group nitride compound material, and serves as a gate of a field effect transistor.  
   
   
       10 . A substrate according to  claim 1 , wherein the active region is made of a III group nitride compound material, and serves as a base of a bipolar transistor.  
   
   
       11 . A substrate according to  claim 1 , wherein the active region is made of a III group nitride compound material, and serves as a junction region of a diode.  
   
   
       12 . A substrate comprising: 
 a crystalline substrate;    a first III-Nitride semiconductor layer provided on the crystalline substrate;    a second III-Nitride semiconductor layer provided on the first semiconductor layer; and    an active region provided in the second semiconductor layer, wherein each of the crystalline substrate and the first semiconductor layer includes a primary surface and a crystal plane provided at least within the primary surface so as to have a stepped portion, and wherein the first semiconductor layer has a high defect region provided by concentrating lattice defects extending toward a tilted direction of the stepped portion.    
   
   
       13 . A substrate according to  claim 12 , wherein the crystal plane of the first semiconductor layer is a tilted surface which is tilted with respect to the primary surface of the first semiconductor layer, and the active region is positioned above lattice defects extending in a direction substantially perpendicular to the crystal plane of the first semiconductor layer.  
   
   
       14 . A substrate according to  claim 12 , wherein a convex-and concave structure is provided over the crystalline substrate, and the crystal plane of the crystalline substrate or that of the first semiconductor layer is part of the convex-and-concave structure.  
   
   
       15 . A substrate according to  claim 14 , wherein a convex portion included in the convex-and-concave structure has a forward mesa structure.  
   
   
       16 . A substrate according to  claim 14 , wherein a convex portion included in the convex-and-concave structure has a cross section in the shape of a triangle pointing upward from the crystalline structure.  
   
   
       17 . A substrate according to  claim 14 , wherein the convex-and-concave structure has a periodic structure.  
   
   
       18 . A substrate according to  claim 12 , wherein the crystal plane of the first semiconductor layer is positioned above the crystal plane of the crystalline substrate.  
   
   
       19 . A substrate according to  claim 12 , wherein the active region is made of a III group nitride compound material, and serves as a light emitting region of a light emitting element.  
   
   
       20 . A substrate according to  claim 12 , wherein the active region is made of a III group nitride compound material, and serves as a gate of a field effect transistor.  
   
   
       21 . A substrate according to  claim 12 , wherein the active region is made of a III group nitride compound material, and serves as a base of a bipolar transistor.  
   
   
       22 . A substrate according to  claim 12 , wherein the active region is made of a III group nitride compound material, and serves as a junction region of a diode.