Patent ID: 7075111

Claim:
A nitride semiconductor substrate having a diameter of 10 mm or more comprising a nitride semiconductor layer having a basic composition represented by Al x Ga 1âˆ’x N (0â‰¦xâ‰¦1), the mass density of said nitride semiconductor layer being 98% or more of a theoretical mass density Ï (x) represented by the following general formula (1): Ï â¡ ( x ) = 4 â¢ ( M x + M N ) 3 â¢ a x 2 â¢ c x â¢ N a , ( 1 ) wherein a x =a GaN +(a AlN âˆ’c GaN )x, wherein c GaN represents an a a-axis length of GaN, and a AlN represents an a-axis length of AlN; c x =c GaN +(C AlN âˆ’c GaN )x, wherein c GaN represents a c-axis length of GaN, and C AlN represents a c-axis length of AlN; M x =M Ga +(M Al âˆ’M Ga )x, wherein M Ga represents the atomic weight of Ga, and M Al represents the atomic weight of Al; M N represents the atomic weight of nitrogen; and N a represents Avogadro's number.