Influence of Fe-doping on the structural, optical, and magnetic properties of ZnO thin films prepared by sol–gel method

Zn1−xFexO thin films with different Fe (0 ⩽ x ⩽ 0.20) content were produced by sol–gel dip coating method. The influence of Fe doping on the structural, optical and magnetic properties of ZnO thin films was investigated. X-ray diffraction has shown that the films are polycrystalline and textured with c-axis of the hexagonal structure along the growth direction. Scanning electron microscope has indicated that the surface of the films is homogeneous with no cracking and the grain sizes tend to decrease with the increase of Fe-doping concentration. Ultraviolet–visible measurements show a reduction in band gap of the films with increase in Fe content from 3.27 eV to 3.10 eV. The magnetic measurements performed at 5, 100, 200 and 300 K using a SQUID magnetometer revealed the dominant paramagnetic behavior until Fe doping ratio of 10% and clear magnetic hysteresis loops at 5 and 100 K for the highest Fe doping ratio of 20%. The observed ferromagnetic behavior is likely related to a partial incorporation of Zn into the Fe3O4, i.e. Fe3−xZnxO4 composition or disorders as well as some defects.

► Sol–gel-derived Fe-doped ZnO thin films.
► A reduction in band gap of the films with increase in Fe content.
► Ferromagnetic behavior in high (20%) Fe-doped ZnO thin films.