NOVELTY - Growing crystalline gallium-containing nitride, comprises: providing an autoclave (1) comprising gallium-containing feedstock in a basket structure in one zone, at least one seed in another zone and a solvent capable of forming a supercritical fluid; processing portion(s) of the feedstock in the fluid to provide a supercritical solution; flowing portion(s) of the solution containing the gallium containing species from one zone through portion of the basket into the other zone; and growing crystalline gallium-containing nitride material from the solution on the seed at second temperature.    USE - The process is useful for growing a crystalline gallium-containing nitride (claimed), which is useful in a variety of applications including optoelectronic devices, lasers, light emitting diodes, solar cells, photoelectrochemical water splitting and hydrogen generation, photodetectors, integrated circuits, and transistors.    ADVANTAGE - The process is simple and scalable up to very large volumes, and is cost effective.    DETAILED DESCRIPTION - Process for growing a crystalline gallium-containing nitride, comprises: providing an autoclave (1) comprising gallium-containing feedstock in a basket structure in one zone, at least one seed in another zone and a solvent capable of forming a supercritical fluid, in which the basket structure being configured to substantially prevent one or more solid portions of the feedstock from being transported from the one zone to the other zone; processing one or more portions of the gallium-containing feedstock in the supercritical fluid to provide a supercritical solution comprising at least gallium containing species at a first temperature; flowing one or more portions of the supercritical solution containing the gallium containing species from the one zone through a portion of the basket into the other zone; and growing crystalline gallium-containing nitride material from the supercritical solution on the seed at a second temperature, in which the second temperature being characterized to cause 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 an autoclave apparatus comprising gallium-containing feedstock in a basket structure in one zone, at least one seed in another zone and a solvent capable of forming a supercritical fluid, in which the basket structure being configured to substantially prevent one or more solid portions of the feedstock from being transported from the one zone to the other zone.    DESCRIPTION OF DRAWING(S) - The figure shows a simplified diagram of an autoclave apparatus.    Autoclave (1)    Opening (2)    Device for heating the autoclave (4, 5, 6)    Baffle (12)    Etching zone. (13)