Thin, hydrogenated silicon and carbon containing films have been deposited by the siliconization procedure on targets made from some metal alloys, pure metals, graphite and Si single crystal. The deposits were investigated by electron microprobe and surface analysis techniques combined with ion sputtering, infrared spectroscopy, mass spectrometry, ellipsometry and by nuclear reaction and backscattering techniques. The stoichiometry of the layers were controlled by particle balance. They are amorphous, semitransparent, and homogeneous throughout the layer. They are hard, non abrasive, and adhere firmly to the substrate. Their density is approximate to 1.5 g cm(-3) for a-C/Si:H and approximate to 2.0 gcm(-3) for a-Si:H, the refractive index n = 2 +/- 0.2, the extinction coefficient k << 0.01. Carbon and silicon form carbidic Si-C bonds, hydrogen is attached both to carbon and to silicon. The deposits are chemically inert to molecular oxygen, but they strongly getter O-ions. Chemical erosion rates of a-C/Si:H films by H+ are a factor 30 less than those of pure carbon films (a-C:H).