A large Group III nitride crystal of high quality with few defects such as a distortion, a dislocation, and warping is produced by vapor phase epitaxy. A method for producing a Group III nitride crystal includes: a first Group III nitride crystal production process of producing a first Group III nitride crystal 1003 by liquid phase epitaxy; and a second Group III nitride crystal production process of producing a second Group III nitride crystal 1004 on the first crystal 1003 by vapor phase epitaxy. In the first Group III nitride crystal production process, the surfaces of seed crystals 1003a (preliminarily provided Group III nitride) are brought into contact with an alkali metal melt, a Group III element and nitrogen are cause to react with each other in a nitrogen-containing atmosphere in the alkali metal melt, and the Group III nitride crystals are bound together by growth of the Group III nitride crystals grown from the seed crystals 1003a to produce a first crystal 1003.

A large Group III nitride crystal of high quality with few defects such as a distortion, a dislocation, and warping is produced by vapor phase epitaxy. A method for producing a Group III nitride crystal includes: a first Group III nitride crystal production process of producing a first Group III nitride crystal 1003 by liquid phase epitaxy; and a second Group III nitride crystal production process of producing a second Group III nitride crystal 1004 on the first crystal 1003 by vapor phase epitaxy by causing a Group III element metal to react with an oxidizing agent and nitrogen-containing gas. In the first Group III nitride crystal production process, the surfaces of seed crystals 1003a (preliminarily provided Group III nitride) are brought into contact with an alkali metal melt, a Group III element and nitrogen are cause to react with each other in a nitrogen-containing atmosphere in the alkali metal melt, and the Group III nitride crystals are bound together by growth of the Group III nitride crystals grown from the seed crystals 1003a to produce a first crystal 1003.

Provided is a method for producing SiC single crystals while maintaining a temperature gradient such that the temperature decreases from within an Si solution inside a graphite crucible toward the solution surface, with the SiC seed crystals that have contacted the solution surface serving as the starting point for crystal seed growth, wherein when the crystal growth surface of the SiC seed crystals, which serves as the starting point for SiC single crystal growth, contacts the solution surface, the height by which the solution rises to the side of the SiC seed crystals is within the range where the SiC single crystals that have grown from the crystal growth surface and the SiC single crystals that have grown from the side grow as one SiC single crystal unit. Also provided is a device for producing an SiC single crystal comprising a graphite crucible, a heating device for heating and melting base materials in the crucible to form a base material solution and maintaining a temperature gradient required for growth of SiC single crystal, a support rod which holds a SiC seed crystal at its bottom end, and a holding structure which maintains the holding by the support rod so that a height by which the solution rises to the side of the SiC seed crystal is within a range where the SiC single crystal that have grown from the crystal growth surface and the SiC single crystal that have grown from the side grow as one SiC single crystal unit.

A large Group III nitride crystal of high quality with few defects such as a distortion, a dislocation, and warping is produced by vapor phase epitaxy. A method for producing a Group III nitride crystal includes: a first Group III nitride crystal production process of producing a first Group III nitride crystal 1003 by liquid phase epitaxy; and a second Group III nitride crystal production process of producing a second Group III nitride crystal 1004 on the first crystal 1003 by vapor phase epitaxy. In the first Group III nitride crystal production process, the surfaces of seed crystals 1003a (preliminarily provided Group III nitride) are brought into contact with an alkali metal melt, a Group III element and nitrogen are cause to react with each other in a nitrogen-containing atmosphere in the alkali metal melt, and the Group III nitride crystals are bound together by growth of the Group III nitride crystals grown from the seed crystals 1003a to produce a first crystal 1003.

A large Group III nitride crystal of high quality with few defects such as a distortion, a dislocation, and warping is produced by vapor phase epitaxy. A method for producing a Group III nitride crystal includes: a first Group III nitride crystal production process of producing a first Group III nitride crystal 1003 by liquid phase epitaxy; and a second Group III nitride crystal production process of producing a second Group III nitride crystal 1004 on the first crystal 1003 by vapor phase epitaxy by causing a Group III element metal to react with an oxidizing agent and nitrogen-containing gas. In the first Group III nitride crystal production process, the surfaces of seed crystals 1003a (preliminarily provided Group III nitride) are brought into contact with an alkali metal melt, a Group III element and nitrogen are cause to react with each other in a nitrogen-containing atmosphere in the alkali metal melt, and the Group III nitride crystals are bound together by growth of the Group III nitride crystals grown from the seed crystals 1003a to produce a first crystal 1003.