Apparatus for obtaining a bulk single crystal using supercritical ammonia

An apparatus for obtaining a bulk single crystal comprising an autoclave for preparing a supercritical solvent equipped with a convection control means for establishing a convection flow, and mounted inside a furnace unit equipped with a heating device and a cooling device,

• wherein the furnace unit is controlled to obtain a temperature gradient within said autoclave by said heating device and/or cooling device,
• wherein the convection control means comprises at least one horizontal baffle having a central opening and/or a space between the baffle and an inner wall of the autoclave, and separating the dissolution zone where a feedstock is located above said baffle from said crystallization zone where a seed is located below said baffle,
• wherein nitride is dissolved in the supercritical solvent containing ammonia and at least alkali metal ions to make the supercritical solution, in which the nitride has a negative temperature coefficient of solubility and the supercritical solution is supplied from said dissolution zone to said crystallization zone in which a seed is located through said convection control means so that nitride crystal is grown on the seed arranged in the autoclave,
• wherein the feedstock made of gallium metal is placed in said dissolution zone and the filling ratio of the feedstock is less than half of said dissolution zone.