SILICON DEPOSITION ON STAINLESS-STEEL SURFACES IN VIEW OF THE CONDITIONING OF FTU VACUUM CHAMBER

The properties of silicon films deposited on stainless steel surfaces held at 77 K, which is approximately the FTU (Frascati Tokamak Upgrade) wall temperature, have been investigated for the first time. Bad adherence and traces of peeling resulted, using the same experimental conditions foreseen for the machine: silane concentration in helium equal to 0.11-0.13, current density in the range 40-150 mA/m2. On the contrary, good results were obtained on substrates held at 273 K. This temperature represents a reasonable compromise for FTU operations.