Effect of Fe doping on the structural and optical properties of ZnS macro-spheres

Objective: Doping of ZnS by the transition metal ions has perceived considerable attention in industrial applications in light-emitting displays and optical sensors. Herein, we have studied the effect of Fe doping on structural and optical properties of ZnS macro-spheres. Methods: ZnS macro-sphere with and without Fe doping are synthesized by a simple and costeffective co-precipitation method and characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and Fourier transform infrared (FTIR) spectroscopy to study the structural properties. Moreover, UV-Vis spectroscopy was performed to investigate the optical properties of un-doped and Fe-doped ZnS macro-spheres. Results: XRD confirms the polycrystalline nature of single-phase cubic structure of as-grown and Fe-doped ZnS macro-spheres. Moreover, the Fe substitute in ZnS inter-layer space thickness decreased and the crystallite size increased. FESEM shows the morphology of semi-spherical macro-spheres with wide micrometer-size distribution (~ 7-8 mu m), agglomerated from several closely embedded primary nano-grains. FTIR spectra found that the specific functional groups associated with the vibrational modes of samples present in the range of 400-800 cm-1. UVVisible spectroscopy shows that the absorption maximum is red-shifted in the case of Fe-doped ZnS. The band gap of as-grown ZnS macro-sphere was found to be 3.46 eV, which was significantly tuned to 3.22 eV by Fe dopant. Conclusions: The synthesized Fe-doped ZnS macro-spheres show improved structural and optical properties and potential optoelectronic device applications.