Investigation of Fe doped ZnO thin films by X-ray absorption spectroscopy

Abstract

Fe doped ZnO thin films with varying Fe doping concentrations have been deposited by rf magnetron sputtering technique on c-Si substrates. X-ray Diffraction (XRD) measurements show the pure wurtzite structure of all the samples. X-ray near edge spectroscopy (XANES) measurements confirm that Fe is present in the samples in Fe²⁺ and Fe³⁺ oxidation states. Extended X-ray Absorption Fine Structure (EXAFS) measurements at Zn and Fe K edges prove that Zn atoms are being substituted by Fe dopants, Zn vacancies are created in the samples near the dopant sites and also support the presence of mixed oxidation states obtained by XANES measurements. Oxygen K-edge XANES results support the conjecture that Fe goes to Zn sites in tetrahedral symmetry. Magnetization measurements show the presence of room temperature ferromagnetism (RTFM) in the samples and saturation magnetization is found to increase as Fe doping concentration increases. The observed ferromagnetism seems to be intrinsic in nature and it is explained in the light of XANES and EXAFS observations.