Adjustment of the selenium amount provided during formation of CuInSe ₂ thin films from the metallic precursors

CuInSe ₂ (CIS) thin films were grown by selenization of sequentially evaporated Cu and In metallic precursors. The adjustment of the Selenium amount provided during the selenization process within a partially closed graphite box for film thicknesses between 0.5-2.5 μm was performed. We obtained CuInSe ₂films with chalcopyrite structure and preferential orientation along the (112) direction plane. XRD patterns showed intense and narrow peaks that indicate high crystallinity corresponding to a Se amount between 120-180 mg. Direct band gap energy between 0.90-0.97 eV, depending on the Se amount and film thickness, and a high absorption coefficient (̃10 ⁵ cm ^-1) were found. A slight improvement in the surface morphology for the optimum Se amount aforementioned was observed. The measured film resistivities varied from 0.1 Ω cm to 40 Ω cm. Thus, the structural, optical and morphological characteristics were dependent of the Se amount provided during the selenization process and after fitting of this selenium, an optimization of the CIS thin films properties and a saving of the Se consumption were achieved.