ABSTRACTPoly-silicon films are obtained at temperatures as low as 400 °C by the catalytic chemical vapor deposition (cat-CVD) method, in which deposition gases are decomposed by the catalytic or pyrolytic reactions with a heated catalyzer near substrates. It is found that there are roughly two modes of deposition conditions such as low gas pressure mode and high gas pressure mode for obtaining poly-silicon films, and also that the Hall mobility of the cat-CVD poly-silicon films of low gas pressure mode sometimes exceeds over 100 cm2/Vs.