Zn incorporation and (CuIn)_(1-x)Zn_(2x)Se_2 thin film formation during the selenization of evaporated Cu and in precursors on Al:ZnO coated glass substrates

摘要

CuInSe_2 thin films with typical 1.0 eV gap energy and tetragonal chalcopyrite structure have been obtained on sodalime glass substrates by the reaction of sequentially evaporated Cu and In layers with elemental selenium vapor, at 500 °C in flowing Ar. When analogous deposition and reaction processes were performed on Al:ZnO coated glasses, some increment in the band gap energy and diminution in the crystalline interplanar spacings have been detected for the resulting films with an extent that depends on the Cu/In atomic ratio of the evaporated precursor layers. This fact has been related to Zn incorporation into the selenized film, with quaternary (CuIn) _(1-x)Zn_(2x)Se_2 compound formation that is influenced by the presence of copper selenide phases during the reaction process. Such deductions are supported by the optical, structural and compositional characterizations that have been performed comparatively on samples prepared by selenization of evaporated metallic precursors with two different Cu/In ratios (0.9 and 1.1) on bare and Al:ZnO coated glass substrates.