Culture method Iii metal nitride single crystal, and a reaction vessel for the process

By Group III metal nitride single crystal material and flux material received in a crucible, the crucible was then introduced to the reaction vessel (1), the reaction vessel (1) accommodated in the outer container, the outer container accommodating then at the same time, supplying a nitrogen-containing gas atmosphere within the pressure container into the outer container, the melt generated in the crucible is cultured group III metal nitride single crystal. The reaction vessel (1) includes a main body (3) accommodated in a crucible and placed in the body cover (2) (3). The body (3) includes a side wall (3b) and a bottom wall (3a), the side walls (3b) has an engaging surface (3d) and the opening in the slot (3c) on the engagement surface (3d). Engaging surface cover (2) is provided with respect to the body (3) has a contact surface on the plate portion (2d) of (2a), and extending from the upper plate portion (2a) out of the surrounding portion of the outer side wall of the flange (3b) of (2b).