Films were prepared under argon and xenon dilution with silane concentrations ranging from 3 to 100% using the very high frequency glow discharge (VHF-GD) technique. The H-content and the microstructure were determined by IR-spectroscopy. A surface profiler was used to measure the stress and thickness of the films. The surface roughness of the films was evaluated by the UV-light reflectance loss. The samples were further characterized by dark- and photoconductivity, by CPM and by PDS, both in annealed and light-soaked state.
Down to silane concentrations of about 10–20% film properties change only little; however, for both dilution series the microstructure parameter shows a minimum and the internal stress a maximum near 20% silane concentration. At still higher rare gas dilution the film properties change drastically. Surprisingly the photoconductivity remains almost constant for all gas dilutions. It is shown how these changes in the film properties are linked with the light induced degradation.