Patent ID: 8728233

Claim:
A method for the production of crystal layers or bulk crystals of group III nitride or of mixtures of different group III nitrides by a low pressure solution growth process wherein by means of precipitation, at a first temperature T 1 in a first temperature range, from a group-III containing fused metal on a group-III-nitride crystal seed placed in the fused metal or on a foreign substrate placed in the fused metal, with the admixture of nitrogen in the fused metal at a pressure P, whereby a solvent additive is added to the fused metal which increases the conversion rate of group III metal to group III nitride in the fused metal, the fused metal running through at least one temperature cycle while said group-III-nitride crystal seed or said foreign substrate is placed in the fused metal, said temperature cycle comprising a first and a second process phase in which the fused metal is cooled after the first process phase from the first temperature T 1 to a second temperature T 2 below the first temperature range and at the end of the second process phase is heated from the second temperature T 2 back to a temperature within the first temperature range, wherein a purifying phase is provided in which a limited volume located above the fused metal is evacuated, the fused metal is heated and then a gas mixture of nitrogen (N 2 ) and hydrogen (H 7 ) is flowed through the limited volume above the fused metal.