CuInSe2 and CuIn3Se5 films were grown by stepwise flash evaporation onto glass and Si substrates held at different temperatures. Transmission electron microscopy (TEM) studies revealed that the films grown above 370 K were polycrystalline, with CuInSe2 films exhibiting larger average grain size than Culn(3)Se(5). Optical absorption studies yielded hand gaps of 0.97 +/- 0.02 and 1.26 +/- 0.02eV for CuInSe2 and Culn(3)Se(5), respectively. Rutherford backscattering spectrometry (RBS) study of the films on Si showed that CulnSe(2)/Si structures included an inhomogeneous interface region consisting of Cu and Si, whereas CuIn3Se5/Si structures presented sharp interface. (c) 2004 Elsevier B.V. All rights reserved.