N-type group III nitride-based compound semiconductor and production method therefor

A method for producing an n-type Group III nitride-based compound semiconductor by a flux process, the method comprising:

• preparing a melt by melting at least a Group III element by a flux;
• supplying a nitrogen-containing gas to the melt;
• and
• growing an n-type Group III nitride-based compound semiconductor crystal on a seed crystal from the melt,
• wherein the Group III element comprises gallium, carbon and germanium are dissolved in the melt, a mole percentage of germanium to gallium in the melt is 0.05 mol % to 0.5 mol %, the flux comprises sodium, and a mole percentage of carbon to sodium is 0.1 mol % to 3.0 mol %, and carbon promotes incorporation of germanium into the n-type Group III nitride-based compound semiconductor crystal, and
• wherein germanium is incorporated as a donor into the semiconductor crystal, and the grown n-type semiconductor crystal has a germanium density of 2×1017/cm3 to 1×1020/cm3 which is larger than a germanium density when the n-type Group III nitride-based compound semiconductor crystal is grown without dissolving the carbon in the melt and a carbon density of 5×1015/cm3 or less.