Room temperature ferromagnetic and ultraviolet optical properties of Co-doped ZnO nanocluster films

Abstract

We prepared 2% and 5% Co-doped ZnO nanocluster films at room temperature (RT) using doped ZnO nanoclusters as building blocks. The nanoclusters are produced by a third-generation magnetron-sputtering-aggregation source. Superconducting quantum interference device (SQUID), photoluminescence (PL), x-ray diffraction (XRD), x-ray photoelectron spectrometer (XPS), and atomic force microscopy (AFM) measurements were done on the samples. The average nanocrystallite size of the nanoclusters was ∼7.5nm. The 2% Co-doped ZnO nanocluster films exhibit significant ferromagnetism and ultraviolet (UV) photoluminescence (PL) at RT. The coercivity (Hc) doubled in the 2% Co-doped samples when compared to the 5% Co-doped samples. A strong UV-PL of ∼3.33eV was observed for the 2% Co-doped ZnO nanocluster film at RT. The 5% Co-doped ZnO nanocluster film showed a ferromagnetic behavior at RT but no UV luminescence.