Investigation of Fe thickness effect on the absorption behavior of ZnO/Fe/ZnO tri-layers thin films

Abstract

In this paper the methodological framework of the spectrophotometric determination of optical properties in a sandwich ZnO/Fe/ZnO thin films, for various Fe interlayer thickness (20, 40, 60 and −80 nm), were analyzed and discussed, based on the absorption measurements. The thin films were produced using (ALD) and Dc magnetron sputtering techniques. The X-ray reflectivity (XRR), Energy-dispersive X-Ray (EDX) analysis is applied along with the scanning electron microscopy (SEM), were used to determine the thickness and roughness for multilayer stacks on the structural characterization and the quantity of elements on the surface, while the optical absorption, was applied to investigate the effect of the variation of Fe interlayer thickness on surface morphology and optical properties of ZnO/Fe/ZnO thin films. Furthermore, the calculated width of the tail of localized states (E_U) experienced a significant increase with the increase of Fe interlayer thickness. The Fe interlayer with 20 nm have maximum values of the electron -phonon interaction (Ee_-p) while the maximum value of the steepness parameter (σ) has occurred in thin films with 80 nm for Fe interlayer thickness. Moreover, the increase of the Fe thickness in the ZnO/Fe/ZnO thin films leads to a decrease in the value of the skin depth (δ), that causes a rise in the charge carrier indicating their influence on the Urbach energy. The above results demonstrates that the ALD is a great technique that introduce a highly efficient and uniform ZnO/Fe/ZnO thin films, that shows remarkable changes in structural and optical properties. Furthermore, incorporation of Fe with different thicknesses on the ZnO thin films indicating their positive influence on the structural and optical properties. This suggests high potential application to be applied in devices fabrication and solar cells.