| 摘要 |
PROBLEM TO BE SOLVED: To lessen the crystal defects of a substrate, and to give sufficient carrier density for formation of an electrode on the substrate, by a method wherein a concentration gradient region, wherein n-type concentration becomes lower as coming nearer to either of the first or the second main surface of the nitride semiconductor substrate, is formed on the nitride semiconductor substrate. SOLUTION: The side face of a base layer 2 is exposed by roughing the surface of the base layer 2 consisting of a nitride semiconductor which is directly formed on a heterogenous substrate 1, a protective film 3 is formed on the surface of a protecting part, the first nitride semiconductor layer 4 is grown as far as to the upper part of the protective film 3 from the side face, the second n-type impurity doped nitride semiconductor layer 4' is formed thereon, and a nitride semiconductor substrate, having concentration gradient, is obtained. Besides, the first nitride semiconductor layer 4 is grown by MOVPE, the second nitride semiconductor layer 4' of the thickness heavier than the first layer 4 is grown by HVPE, and the nitride semiconductor substrate, having less crystal defects, can be obtained. |
