Patent ID: 8361222

Claim:
A method for producing a Group III nitride-based compound semiconductor crystal in which a Group III nitride-based compound semiconductor crystal is grown by reacting nitrogen (N) with a Group III element of gallium (Ga), aluminum (Al), or indium (In) in a flux mixture comprising an alkali metal, the method comprising: placing, in the flux mixture, a plate-form self-standing substrate comprising a Group III nitride-based compound semiconductor and comprising a +c-plane main surface, the substrate comprising a plate-form seed crystal, such that a line normal to the +c-plane of the seed crystal is maintained in a direction within ±30° with respect to a horizontal plane; and growing a semiconductor crystal on a Group III element-face of the seed crystal while the Group III element-face of the plate-form seed crystal is exposed to the flux mixture and a nitrogen-face of the seed crystal is substantially not exposed to the flux mixture, wherein the placing of the plate-form self-standing substrate comprises placing the plate-form seed crystal such that the nitrogen-face of the seed crystal comes into close contact with a wall of a flux mixture container.