CuIn1-xGaxSe2 polycrystalline thin films were prepared by the two-step method. Cu-In-Ga metallic precursors were deposited sequentially or simultaneously using both Cu-Ga (23 at.%) alloy and In targets by DC magnetron sputtering. The metallic precursor films were selenized in vacuum evaporation system. It is found that the CuIn1-xGaxSe2 chalcopyrite phase was formed from In-Se compounds (InSe and In2Se3) and Cu3Ga during the early stage of selenization. The flattening of CuIn1-xGaxSe2 film seemed to be achieved by the formation of liquid In-Se compound phase during the selenization. The fabricated CuIn1-xGaxSe2 films showed a smooth surface morphology and contained a single chalcopyrite phase. (C) 2003 Elsevier Science B.V. All rights reserved.