Patent ID: 7387678

Claim:
A GaN substrate comprising: a GaN single crystal substrate including a low dislocation region and high dislocation regions, the low dislocation region having a first density of threading dislocations, the high dislocation regions each having a second density of threading dislocations, the low dislocation region surrounding each high dislocation region, the second density of threading dislocations in high dislocation regions being higher than the first density of threading dislocations in the low dislocation region, the low dislocation region and the high dislocation regions appearing at a surface of the GaN single crystal substrate; a first Al x Ga 1-x N intermediate epitaxial layer (0<x<0.24) provided on the surface in a thickness of less than (−5x−1.2) micrometers; and a GaN epitaxial layer provided at the first Al x Ga 1-x N intermediate epitaxial layer.