Amorphous silicon-carbon thin films were obtained on silicon and steel substrates, by irradiating a mixture of Ar-diluted silane and acetylene by Xe-2* excimer lamp in a reaction chamber. The influence of the deposition parameters on film properties was analyzed by different techniques, Film composition was determined by Rutherford backscattering spectroscopy and elastic recoil detection analysis and the structure of the material was studied by infrared and Raman spectroscopies, x-ray photoelectron and Auger electron spectroscopies. Thickness and refractive index were evaluated by ellipsometry. Structural studies reveal that carbon and silicon are present in the films mainly forming homonuclear and hydrogenated bonds. Compositional analyses indicate high carbon concentrations and only slight variations for dramatical changes of precursor gas mixture composition. Lamp power tuning affects the growth rate and film density. Moreover, oxygen is incorporated when the layers are exposed to the atmosphere forming silicon oxides.