METHOD FOR PRODUCING AlN SINGLE CRYSTAL

PROBLEM TO BE SOLVED: To provide a method for producing a high quality AlN single crystal having few defects at a high growth rate and at a low cost.SOLUTION: An AlN single crystal 11 is grown on a sapphire substrate 9 by a solution process using a solution 10 containing Cu-Ti-Al-Si as a component and the sapphire substrate 9 of which surface is not nitrided in a horizontal growth furnace 2. As the cheap sapphire substrate 9 of which surface is not nitrided is used, the AlN single crystal 11 may be produced at a low cost. As the horizontal growth furnace 2 is used, when a pit 12 is formed by partial melting of a part of the surface of the sapphire substrate 9, the AlN single crystal 11 may be grown in the horizontal direction so that it may cover the pit 12 to form a void 13. As a result, a stress on an interface between the sapphire substrate 9 and the AlN single crystal 11 may be reduced by the void 13, which may lead to decrease the defects formed in the AlN single crystal 11.