CdS thin films of an n-type window layer of the CdTe thin film solar cell were grown by a chemical bath deposition method. The physical properties of the CdS thin films were investigated depending on the various substrates and the stirring speed. Surface morphological study was carried out by the scanning electron microscope and atomic force microscope. The structural property was investigated by using the Xray diffraction measurement and transmission electron microscopy. The structural characteristic of the CdS films depend on the substrate crystal structure. The stirring speed effect to the kinetics of the CdS film growth proved the heterogeneous growth mechanism proposed by Ortega-Borges and Lincot. (C) 2010 Elsevier B. V. All rights reserved.