The epitaxial thickening of polycrystalline Si films on glass substrates is of great interest for the realization of crystalline Si thin film solar cells and other large-area thin film devices. In this paper we report on the epitaxial growth of Si at temperatures below 600 degreesC on polycrystalline seed layers using electron-cyclotron resonance chemical vapor deposition. The Si seed layers were prepared by aluminum-induced crystallization. The quality of the ECRCVD-grown films strongly depends on the orientation of the underlying seed layer grains. Due to a mainly favorable orientation of the seed layers more than 73% of the substrate area were epitaxially thickened. It turned out that a (100) preferential orientation is favorable for epitaxial thickening. This, however, is not the only requirement for successful low-temperature epitaxial growth of Si. (C) 2004 Elsevier B.V. All rights reserved.