Composition, structure and optical properties of sputtered thin films of CuInSe2

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 TSub not exceeding 200 °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 Eg, 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 (> 104 cm− 1) were found.