Patent ID: 7303630

Claim:
A method of growing a GaN crystal comprising the steps of: preparing an undersubstrate; forming a dotted mask pattern made of a material inhibiting GaN from growing partially on the undersubstrate; providing the undersubstrate with a seed mask with a plurality of regularly aligning isolated, dotted seeds made of a material inhibiting GaN from growing; forming seeded parts which are parts of the undersubstrate covered with the seed mask and a non-seeded part which is a part of the undersubstrate not covered with the seed mask; epitaxially growing the GaN crystal on the non-seeded part of the undersubstrate but not growing the GaN crystal on the seeded parts of the undersubstrate at the beginning of GaN growth; forming a plurality of reverse-conical pits having facets slantingly extending from edges of the seeded parts to the non-seeded part; forming protrusions of GaN crystals which have reversed orientation different from that of the GaN crystal on the non-seeded part by 180 degrees and project slantingly from the slanting facets; extending the protrusions so as not to touch the seeds; unifying the protrusions near an upper middle of the seeded parts; covering the whole seeded parts with the protrusions; increasing a thickness of the GaN crystal on the non-seeded part with growing of the protrusions above the seeded parts; increasing a thickness of the GaN crystal as a whole; and obtaining the GaN crystal having normal-oriented regions formed on the non-seeded part and the reverse-oriented regions formed on the seeded parts.