We prepared device-grade polycrystalline silicon thin films on glass substrates at 450 degrees C, by reactive thermal-chemical vapour deposition employing Si(2)H(6) and F(2) as source gases. The nucleation and growth of the poly-Si thin films were investigated, and the process pressures were varied from 533 to 933 Pa. Thin films with thickness of 2 to 200 nm were prepared and their crystallinity and morphological properties were characterized. The incubation time is shorter than 30 s; 533 Pa yields higher crystallinity. However a trade-off exists between growth rates and grain sizes. We proposed a model for comparing our technique with conventional low-pressure chemical vapor deposition. (C) 2008 Elsevier B.V. All rights reserved.