Abstract
A bulk GaN crystal with improved structural quality was grown via ammonthermal growth with polycrystalline GaN nutrient and a sodium amide mineralizer. The threading dislocation density estimated by plan-view transmission electron microscopy observations was less than 1×106 cm-2 for the Ga-face and 1×107 cm-2 for the N-face. There was no dislocation generation observed at the interface on the Ga-face although a few defects were generated at the interface on the N-face. The chemical etching revealed macroscopic grains on the N-face.