Various silicon films were prepared by thermal and UV photo-CVD processes. The reactants were SiH₄, Si₂-H_6, SiH₂F₂, SiF₄, and H₂. Silicon films grown at temperatures below 5000 were either amorphous or crystalline depending on the process conditions, and the growth rates ranged between 5 and 80 Å/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 o1 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.