Process and device for the deposition of an at least partially crystalline silicium layer on a substrate

In a process and device for depositing an at least partially crystalline silicon layer a plasma is generated and a substrate (24) is exposed under the influence of the plasma to a silicon-containing source fluid for deposition of silicon therefrom. A pressure drop is applied between a location (12) where the source fluid is supplied and the substrate (24). In addition to the source fluid an auxiliary fluid is also injected which is able to etch non-crystalline silicon atoms. The substrate (24) is exposed to both the source fluid and the auxiliary fluid.