Co-doped ZnO Thin Films Fabricated by a Nanocluster-Beam Deposition System and the Influence of Flow Rate of Helium Gas on Their Properties

As a pioneer, Co-doped ZnO nanocluster-assembled thin films were fabricated by a nanocluster-beam deposition system and the influence of the flow rate of helium gas on the properties of the films was also investigated. Transmission electron microscopy indicated that Co-doped ZnO nanoclusters maintained a wurtzite structure as that of bulk materials. Also, it is found that the average size of ZnO nanoclusters decreased with the increased flow rate of helium gas. Two photoluminescence (PL) bands at 378 and 510 nm were observed. The Co-doped ZnO nanocluster-assembled thin films exhibited ferromagnetic property at room temperature. As the flow rate of helium gas increased, the corresponding saturation magnetization of the nanocluster-assembled thin films decreased from 11 to 6 μemu.