PVT-method and device for producing single crystals in a safe manner with regard to the process

The aim of the invention is to use hydrogen as a process gas in a PVT method. For this purpose, a special safeguard is required in order to be able to carry out the method in a safe manner with regard to the process. A device for carrying out the PVT method consists of a highly heatable growth cell (1) that is arranged in a process chamber (4), the wall of which consists of a heat-resistant quartz glass. The process chamber (4) is filled with hydrogen via an inlet valve (5). A heating device (6) consists of an induction coil (7) which surrounds the process chamber (4) at the height of the growth cell (1), and the growth cell (1) is heated from over 2,000 DEG C up to 2,400 DEG C. The use of hydrogen, however, presents the problem of the hydrogen mixing with the oxygen of the ambient air in the event of a possible crack in the quartz glass of the process chamber (4) such that a combustible gas mixture is produced which would be instantly ignited on the hot parts of the device. The process chamber (4) is therefo