Ammonothermal growth of bulk GaN

Bulk GaN crystals have been realized by the basic ammonothermal method. Three-dimensional polyhedron-shaped crystals in size of approximately 5 mm and their sliced wafers demonstrated the feasibility of the basic ammonothermal method to produce GaN wafers. Clear crystallographic facets of N face and m planes were observed although Ga face was decorated with angled facets of {1 0 1¯ 1} planes. The growth rate and growth nature showed distinct anisotropy. The transmission electron microscopy revealed high quality of microstructure, whereas selective etching and X-ray diffraction revealed multiple grains, which were presumably caused by insufficient structural quality of seed crystals.