Semiconductor substrate and method of fabricating the same

Abstract

A semiconductor substrate includes a substrate including a plurality of semispherical protrusions disposed at an interval on a first plane of the substrate, and a first semiconductor layer disposed on the first plane of the substrate.

What is claimed is: 
     
         1 . A semiconductor substrate, comprising:
 a substrate comprising a plurality of semispherical protrusions disposed at an interval on a first plane of the substrate; and   a first semiconductor layer disposed on the first plane of the substrate.   
     
     
         2 . The semiconductor substrate of  claim 1 , wherein the ratio of the total surface area of the plurality of semispherical protrusions to the surface area of the first plane is at least one. 
     
     
         3 . The semiconductor substrate of  claim 2 , wherein the semispherical protrusions have a bottom surface width of 5 μm or less. 
     
     
         4 . The semiconductor substrate of  claim 1 , wherein the substrate comprises sapphire and the first semiconductor layer comprises gallium nitride. 
     
     
         5 . The semiconductor substrate of  claim 4 , further comprising:
 a second semiconductor layer disposed on a first surface of the first semiconductor layer opposite to the first plane of the substrate; and   cavities disposed in portions of the first semiconductor layer and the second semiconductor layer.   
     
     
         6 . The semiconductor substrate of  claim 5 , wherein the cavities comprise a width equal to the interval between semispherical protrusions, respectively, and the cavities are disposed on the first surface of the first semiconductor layer and between the semispherical protrusions. 
     
     
         7 . The semiconductor substrate of  claim 5 , wherein the cavities comprise a plurality of rectangles each comprising a long side disposed in a first direction, and the cavities are spaced apart from each other in a second direction orthogonal to the first direction. 
     
     
         8 . The semiconductor substrate of  claim 7 , wherein the first direction is a {1-100} direction of the first semiconductor layer or an equivalent direction to the {1-100} direction. 
     
     
         9 . A semiconductor substrate, comprising:
 a substrate comprising a plurality of curved concavities disposed at an interval on a first plane of the substrate; and   a first semiconductor layer disposed on the first plane of the substrate.   
     
     
         10 . The semiconductor substrate of  claim 9 , wherein the curved concavities have a bottom surface width of 5 μm or less. 
     
     
         11 . The semiconductor substrate of  claim 9 , wherein the substrate comprises sapphire and the first semiconductor layer comprises gallium nitride. 
     
     
         12 . A semiconductor device, comprising:
 the first semiconductor layer lifted-off from the semiconductor substrate of  claim 1 ;   a first compound semiconductor layer disposed on the first semiconductor layer;   an active layer disposed on the first compound semiconductor layer; and   a second compound semiconductor layer disposed on the active layer.   
     
     
         13 . A semiconductor device, comprising:
 the second semiconductor layer lifted-off from the semiconductor substrate of  claim 5 ;   a first compound semiconductor layer disposed on the second semiconductor layer;   an active layer disposed on the first compound semiconductor layer; and   a second compound semiconductor layer disposed on the active layer.