Hot-wire chemical vapor deposition (HWCVD) and plasma-enhanced chemical vapor deposition (PECVD) of Si thin films show different growth kinetic processes. According to the fractal analysis, the root-mean-square surface roughness 6 and the film thickness d have the relation of delta similar to d(beta), where beta is the dynamic scaling exponent related to the film growth mechanism. It was found that beta is 0.44 for Si films prepared by HWCVD and 0.24 by PECVD. The former refers to a stochastic deposition while the latter corresponds to the finite diffusion of the radicals. Monte Carlo simulations indicate that the sticking process of growth radicals play an important role in determining the morphology of Si films. (C) 2007 Published by Elsevier B.V.