Optical properties, microstructure, and multifractal analyses of ZnS thin flms obtained by RF magnetron sputtering

Abstract

The morphology, structure and optical properties of zinc sulfide (ZnS) thin films prepared through radio-frequency (RF) magnetron sputtering have been analyzed using atomic force microscopy (AFM), UV–Vis–NIR spectrophotometry, X-ray diffraction, and multifractal analyses. The X-ray diffraction patterns revealed that all ZnS thin films show a single peak at around 29.6°, which has been ascribed to the (111) planes of sphalerite phase, indicating that the growth direction of the films is the [111] direction. UV–Vis–NIR transmittance spectra were used to determine the refractive index of the samples, their thickness, and their band gap energy, showing the optical and semiconductor properties a clear dependence of the film thickness. Finally, ZnS thin films were characterized and analyzed by atomic force microscopy (AFM) measurements and multifractal analyses for a complex and precise interpretation of the 3-D surface microtexture characteristics. The multifractal examinations of the samples revealed a particular distribution at the nanometric level associated with multifractal surface characteristics. These experimental results are corroborated, presented, and discussed together with the essential stereometric parameters of the thin films. The combination of the different experimental information and the comprehensive stereometric and multifractal analyses provide new and deeper insight into the ZnS thin films that would be exploited to develop novel micro-topography models.