Various silicon films were prepared by thermal-and UV photo-CVD processes. The reactants were SiH₄, SiH₂F₂, SiF₄, and H₂. Silicon films grown at temperatures below 500℃ were either amorphous or crystalline depending on the process conditions, and the growth rates ranged between 5 and 80Å/min. The film obtained by photo-CVD using fluoro-silanes as the reactants was crystalline even when the deposition temperature was as low as 250℃. Analyses of the film by RBS, SIMS, XRD, and ex-situ IR indicated that the film grown from silanes was contaminated by oxygen and other impurities while one from fluoro-silanes was relatively low in the impurities. The film crystallinity was higher in the latter case than the former.