| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a semiconductor material which has a nitride semiconductor layer of superior crystallinity less likely to generate crack and pit, and to provide a method for manufacturing the same. <P>SOLUTION: On an Si substrate 10 or on an intermediate layer 20 formed thereon, a composition graded layer 30 is formed. The composition graded layer 30 is composed of Al<SB>X</SB>Ga<SB>1-X</SB>N wherein the composition is graded so that an Al content ratio in the composition is graded continuously or discontinuously in a crystal growth direction. On the composition graded layer 30, a superlattice composite layer 40 wherein high Al content layers 41 composed of Al<SB>Y</SB>Ga<SB>1-Y</SB>N and low Al content layers 42 composed of Al<SB>Z</SB>Ga<SB>1-Z</SB>N are alternately laminated is formed, and on the superlattice composite layer 40, a nitride semiconductor layer 50 is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT |
