Optical, Photocurrent, Electrical, Structural, and Morphological Properties of Magnetron Sputtered Pure and Iron-Doped Zinc Oxide Thin Films

Abstract

Due to its excellent physical and chemical properties, transition metal-doped zinc oxide has potential applications in different fields. In this research paper, pure and iron-doped ZnO films were deposited by thermal oxidation of sputtered metallic zinc and iron. The effect of iron (Fe) doping on the optical, morphology, structural, electrical, and photocurrent properties of zinc oxide films was examined. The X-ray diffraction analysis shows a wurtzite structure with preferential orientation for all films, where the high texture coefficient values (above 3) corresponded to the (002) plane. Fe doping reduced the crystallite size from 12.3 to 8.7 nm and lattice constants c and a values from 5.19 to 5.155 Å and from 3.236 to 3.203 Å respectively. The different calculated structure parameters, confirm the incorporation of Fe (Fe3+) in the ZnO lattice. The surface morphology of thin films measured using atomic force microscopy revealed that the Fe doping could markedly decrease the grains size from 248 to 54 nm and the Root–Mean–Square roughness of films from 5.27 to 4.22 nm. For all films, the transmittance analysis shows a transmittance above 90% in the visible region and with an increase in the Fe concentration, the transmittance, and the absorption in the ultraviolet region were increased. The gap energy of ZnO strongly increased from 3.26 to 3.51 eV with doping. The effect of Fe doping on different optical parameters was discussed in detail. The photoluminescence analysis of pure and doped ZnO exhibits one ultraviolet emission (384 nm) and green emission. Compared to pure ZnO, the ultraviolet peak intensity decreased as Fe content increased. The electrical resistivity was decreased and the photocurrent properties of ZnO were enhanced by Fe doping. In this report, Fe-doped ZnO films exhibited remarkable properties. Therefore such films can be usefully used in different device applications.