CVD reactor with retractable process chamber ceiling

The invention relates to a device for depositing one or more layers on a substrate (4) having a in a reactor housing (1) arranged in the process chamber (2) having a heated base (3), on which the substrate lies, and a parallel to bottom (3) extending ceiling (5) and a gas inlet element (6) for introducing process gases. In order to develop CVD reactors of the aforementioned type for use advantageously, it is proposed that the distance (H) of the process chamber cover (5) to the process chamber base (3) to close to zero can be reduced.