Structural and optical properties of Fe-doped ZnO transparent thin films

We investigated the structural, morphological, and optical properties of Fe-doped ZnO transparent thin films spin coated on ordinary and FTO glass substrates using X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectrometric refiectometry (SR) techniques. The XRD spectra showed the polycrystalline films with a preferential orientation along the c-axis and without any impurity phases. SEM images revealed that the randomly oriented matrix shaped nanoparticles of ZnO doped with 1% Fe (with respect to Zn) transformed into cylindrical long grains at higher dopant concentration (4% Fe). The surface reflectance of the Fe-doped ZnO film, particularly in the wavelength range of 400-650 nm, was approximately two fold higher than the ones with un-doped ZnO film. However, the transmittance of the doped film decreased only by similar to 10%. The band gap, derived with the aid of measured transmittance curves, of un-doped ZnO thin film ca. 3.26 eV was decreased to ca. 3.21 eV when Fe ions were doped into the film and was independent to the dopant concentration. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.