NOVELTY - Growing a crystalline gallium-containing nitride includes growing crystalline gallium-containing nitride material from the supercritical solution on the seed at a second temperature which causes the gallium containing species to form the crystalline gallium containing nitride material on the seed.    USE - Method for growing a crystalline gallium-containing nitride used in manufacturing optoelectronic devices, lasers, LEDs, solar cells, photoelectrochemical water splitting and hydrogen generation, photodetectors, integrated circuits, or transistors.    ADVANTAGE - The method can operate with components that are relatively simple and cost effective to manufacture.    DETAILED DESCRIPTION - Growing a crystalline gallium-containing nitride comprises:    (A) providing a high pressure apparatus comprising gallium-containing feedstock in one zone, seed(s) in another zone, an azide mineralizer, and metal(s), where the azide mineralizer and the metal are provided in a predetermined ratio such that nitrogen generated by decomposition of the azide mineralizer and hydrogen generated by reaction of the metal with a supercritical fluid are in a ratio of approximately 1:3;    (B) processing portion(s) of the gallium-containing feedstock in the supercritical fluid to provide a supercritical solution comprising gallium containing species at a first temperature; and    (C) growing crystalline gallium-containing nitride material from the supercritical solution on the seed at a second temperature which causes the gallium containing species to form the crystalline gallium containing nitride material on the seed.    An INDEPENDENT CLAIM is included for a system for growing a crystalline gallium-containing nitride, comprising a high pressure apparatus comprising gallium-containing feedstock in one zone, seed(s) in another zone, an azide mineralizer, and metal(s).    DESCRIPTION OF DRAWING(S) - The drawing is a sectional diagram of an autoclave apparatus.    Autoclave apparatus (1)    Cooling mechanism (6)    Baffle (12)    Etching zone (13)    Crystallization zone (14)