An ammonothermal method for growing group III-nitride crystals, comprising:
- (a) loading group III-containing source materials, group III-nitride seed crystals, and mineralizers into a reaction vessel;
- (b) filling the reaction vessel with ammonia;
- (c) adding extra nitrogen (N2) pressure in the reaction vessel to avoid disassociation of the ammonia into N2 and H2;
- (d) raising the reaction vessel's temperature to attain a supercritical state for the ammonia;
- and
- (e) ammonothermally growing the group III-nitride crystals, wherein convection of the supercritical ammonia transfers the source materials and deposits the transferred source materials onto the seed crystals.