Microstructure and optical properties of Fe-doped ZnO thin films prepared by DC magnetron sputtering

Abstract

ZnO and Fe-doped ZnO thin films were prepared by DC magnetron sputtering. The microstructure and optical properties of the two samples were compared and studied by atomic force microscopy (AFM), X-ray diffraction (XRD), UV–vis spectra and photoluminescence (PL) spectra. The results show that ZnO thin films were successfully prepared with smooth surface and preferred orientation growth, showing structure of single crystal. The surface and the crystal quality of ZnO thin film was improved when doped with Fe. And the average transmission decreased and the absorption edge red-shifted, which might be due to the formation of the defect level of Fe below the conduction band of ZnO. There were three photoluminescence peaks in ZnO thin films, one double ultraviolet peak at 370nm and 410nm and one blue peak at 466nm, whose intensity all increased when doped with Fe. The peak at 370nm originates from the transition emission of the electrons from the conduction band to the valence band; the peak at 410nm is associated with electron transition from the conduction band to the VZn level while the blue peak might be due to the intrinsic defect of Zni.