It is reported that the direct contact between Al and amorphous silicon (a-Si) enhances the crystallization of a-Si films. But the polycrystalline silicon (poly-Si) films crystallized by the direct contact of Al metal film suffer the problems of rough surface. In our study, we utilized the AlCl3 vapor during the a-Si films deposition instead of Al metal film to enhance crystallization. X-ray diffraction ( XRD) shows that the AlCl3 vapor so successfully enhanced the crystallization of a-Si films that the crystallization was completed in 5 h at 540 degrees C. And the orientation of the poly-Si film deposited with AlCl3 vapor is much more random than that of annealed with Al metal under layer. But the average grain size is much larger than that. Moreover, the surface of the AlCl3-induced crystallized poly-Si film was much smoother than that of the Al-induced poly-Si film. The Al and Cl incorporation into the poly-Si film was confirmed using X-ray photoelectron spectroscopy (XPS) and found that the quantity of Al and Cl incorporated into the Si film was below the detection limit of XPS. (C) 2007 Elsevier B. V. All rights reserved.