Method of preparing a compound semiconductor crystal

A method of preparing a compound semiconductor crystal containing carbon, comprising the following steps:

• a) selecting a partial pressure of a carbon oxide gas;
• b) sealing said carbon oxide gas having said partial pressure, and a semiconductor raw material, in a gas-impermeable airtight vessel;
• c) after said step b), increasing a temperature of said airtight vessel to melt said raw material in said airtight vessel and thereby form a melted material from said raw material;
• and
• d) after said step c), decreasing said temperature of said airtight vessel to solidify said melted material and thereby grow said compound semiconductor crystal containing a resultant content of said carbon, wherein said resultant content of said carbon is dependent on said partial pressure of said carbon oxide gas selected in said step a).