| 摘要 |
A nitride semiconductor substrate having a diameter of 10 mm or more, which has a single-layer structure composed of a nitride semiconductor layer having a basic composition represented by Al<SUB>x</SUB>Ga<SUB>1-x</SUB>N (0<=x<=1), or a multi-layer structure comprising the nitride semiconductor layer, the mass density of the nitride semiconductor layer being 98% or more of a theoretical mass density rho (x) represented by the following general formula (1): <maths id="MATH-US-00001" num="1"> <MATH OVERFLOW="SCROLL"> <MTABLE> <MTR> <MTD> <MROW> <MROW> <MROW> <MI>rho</MI> <MO></MO> <MROW> <MO>(</MO> <MI>x</MI> <MO>)</MO> </MROW> </MROW> <MO>=</MO> <MFRAC> <MROW> <MN>4</MN> <MO></MO> <MROW> <MO>(</MO> <MROW> <MSUB> <MI>M</MI> <MI>x</MI> </MSUB> <MO>+</MO> <MSUB> <MI>M</MI> <MI>N</MI> </MSUB> </MROW> <MO>)</MO> </MROW> </MROW> <MROW> <MSQRT> <MN>3</MN> </MSQRT> <MO></MO> <MSUBSUP> <MI>a</MI> <MI>x</MI> <MN>2</MN> </MSUBSUP> <MO></MO> <MSUB> <MI>c</MI> <MI>x</MI> </MSUB> <MO></MO> <MSUB> <MI>N</MI> <MI>a</MI> </MSUB> </MROW> </MFRAC> </MROW> <MO>,</MO> </MROW> </MTD> <MTD> <MROW> <MO>(</MO> <MN>1</MN> <MO>)</MO> </MROW> </MTD> </MTR> </MTABLE> </MATH> </MATHS> wherein a<SUB>x</SUB>=a<SUB>GaN</SUB>+(a<SUB>AlN</SUB>-a<SUB>GaN</SUB>)x, wherein a<SUB>GaN </SUB>represents an a-axis length of GaN, and a<SUB>AlN </SUB>represents an a-axis length of AlN; c<SUB>x</SUB>=c<SUB>GaN</SUB>+(c<SUB>AlN</SUB>-c<SUB>GaN</SUB>)x, wherein c<SUB>GaN </SUB>represents a c-axis length of GaN, and C<SUB>AlN </SUB>represents a c-axis length of AlN; M<SUB>x</SUB>=M<SUB>Ga</SUB>+(M<SUB>Al</SUB>-M<SUB>Ga</SUB>)x, wherein M<SUB>Ga </SUB>represents the atomic weight of Ga, and M<SUB>Al </SUB>represents the atomic weight of Al; M<SUB>N </SUB>represents the atomic weight of nitrogen; and N<SUB>a </SUB>represents Avogadro's number.
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