Optical and magnetic properties of diluted magnetic semiconductor Zn0.95M0.05S nanorods prepared by a hydrothermal method

Pure ZnS and doped Zn0.95M0.05S (M -= Cr, Ni, Co, Fe and Mn) nanorods were successfully prepared by a hydrothermal method. The effects of the variety of doped elements on the crystal microstructure, morphology, optical and magnetic properties of the samples were investigated by means of Xray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray energy dispersive spectrometry, photoluminescence spectroscopy, UV-Visible diffuse reflectance spectroscopy and vibrating sample magnetometry. The experimental results show that all samples synthesized by this method possess single phase wurtzite structure with good crystallization, transition metal ions (M = Cr, Ni, Co, Fe and Mn) substitute for the lattice site of Zn2+ and generate single-phase Zn0.95M0.05S nanostructures. The morphologies of the samples are one-dimensional nanorods with good dispersion. The optical band gap of doped Zn0.95M0.05S decreases as the doping ion radius increases, and red shift occurs compared to undoped ZnS nanocrystals. Photoluminescence spectra exhibit clear ultraviolet emission and blue emission. Magnetic measurements indicate that the undoped and doped ZnS samples are ferromagnetic at room temperature.