| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a group III nitride semiconductor substrate in which cracking in the Al<SB>b</SB>Ga<SB>1-b</SB>N (0<b≤1) layer on the surface of a substrate can be reduced. <P>SOLUTION: The III nitride semiconductor substrate 1 includes a first layer 11 composed of Al<SB>a</SB>Ga<SB>1-a</SB>N (0≤a<1) having a constant composition a, a second layer 12 formed on the first layer 11, and a third layer 13 formed on the second layer 12 and composed of Al<SB>b</SB>Ga<SB>1-b</SB>N (0<b≤1) having a constant composition b. The second layer 12 is composed of Al<SB>x</SB>Ga<SB>1-x</SB>N (0<x<1) having a composition x varying in the thickness direction such that the composition x of the surface touching the third layer 13 is higher than the composition x of the surface touching the first layer 11. The compositions a, b and x satisfy a relation a<x<b. <P>COPYRIGHT: (C)2007,JPO&INPIT |
