Structural, morphological and optical properties of rf - Sputtered CdS thin films

Cadmium sulfide (CdS) nanocrystalline semiconductor thin films were deposited using the technique of magnetron sputtering in radio - frequency plasma. Structural, morphological and optical characterizations of the prepared CdS thin films were carried out. The films were polycrystalline and well textured, with (002) crystallographic planes oriented parallel to the surface (crystallite sizes were between 30.6 nm up to 48.2 nm). RMS surface roughness was in the nanometer range and decreases with increasing film thickness. Optical constants (refractive indices and extinction coefficients) as well as film thicknesses (between 56.4 nm and 174.6 nm) and surface rugosities were computed by spectroscopic ellipsometry. This optical method was combined with optical spectrophotometry (absorption coefficients, optical transmittances, etc.) in UV - VIS - NIR for a better verification of the results. The range for the obtained values of optical band gaps is between 2.3 eV and 2.36 eV. (C) 2016 Elsevier Ltd. All rights reserved.