Structural, morphological and optical properties of Sn-doped CuInS2 thin films gown by double source thermal evaporation method were studied. Firstly, the films were annealed in vacuum after evaporation from 250 to 500 degrees C for Sn deposition time equal to 3 min. Secondly, the films deposited for several Sn evaporation times were annealed in vacuum after evaporation at 500 degrees C. The X-ray diffraction spectra indicated that polycrystalline Sn-doped CuInS2 films were obtained and no Sir binary or ternary phases are observed for the Sir evaporation times equal to 5 min. Scanning electron microscopy observation revealed the decrease of the surface crystallinity with increasing the Sn evaporation times and the annealing temperatures. The Sn-doped samples after annealing have bandgap energy of 1.42-1.50 eV Furthermore, we found that the Sn-doped CuInS2 thin films exhibit N-type conductivity after annealing. (c) 2005 Elsevier B.V. All rights reserved.