Freestanding III-Nitride Single-Crystal Substrate and Method of Manufacturing Semiconductor Device Utilizing the Substrate

A III-nitride crystal growth method comprising:

• a substrate-constituting step of preparing a III-nitride crystal starting substrate structured in a pattern of alternating first/second crystallographically distinct regions, the pattern of first/second regions appearing in a side of the starting substrate defining a major surface thereof;
• and
• a growth step of growing III-nitride crystal onto the starting substrate major surface to initially create over the first regions of the starting substrate first zones having high-density dislocations, and over the second regions of the starting substrate second zones having low-density dislocations, and of continuing the III-nitride crystal growth so as to cover over and bury the first zones with the second zones, such that the III-nitride crystal possesses both regions having high-density dislocations and regions having low-density dislocations, and such that the ratio of the dislocation density of the high-dislocation-density regions to the crystal's average dislocation density is 2 or greater.