The authors report on the study of the initial growth process of crystalline silicon films deposited on aluminum-coated polyethylene napthalate (PEN) by inductively coupled plasma (ICP-) chemical vapor deposition (CVD) at room temperature. By using micro-Raman spectroscopy and transmission electron microscopy, microstructures of silicon films on bare and aluminum-coated substrates were studied with different film thicknesses. Compared to the films deposited on bare PEN, the phase transition from amorphous to crystalline was observed when increasing the thickness of the resultant films on aluminum-coated substrates. It indicates that the amorphous silicon layer formed under the assistance of the aluminum layer is very important to obtain highly crystallized silicon films on PEN substrates in our experiment. Therefore, the selective deposition of highly crystallized silicon films on plastic substrates can be performed by adjusting the distribution of aluminum on plastic substrates at room temperature in ICP-CVD process. (C) 2007 Elsevier B.V. All rights reserved.