Thin films of copper indium selenide (CuInSe2) were produced by radio frequency (RF) sputtering due to the ability of this technique to achieve stoichiometric layers and its scalability to large-area devices. Results of energy dispersive analysis of X-rays (EDAX) revealed that the sputtered films were near to stoichiometry for substrate temperatures T-sub not exceeding 200 degrees C. X-ray diffraction (XRD) patterns indicate that the films exhibited some pattern similar to that of bulk crystals of tetragonal chalcopyrite, predominantly [ 112] oriented. Based on the XRD patterns, the lattice parameters and grain sizes were examined. The band gap E,, estimated from optical absorption data, was between 0.6-1.08 eV, depending on sputtering conditions such as substrate temperature and bias voltage. High optical absorption coefficients (> 10(4) cm(-1)) were found. (c) 2005 Elsevier B.V. All rights reserved.