Shape-controlled synthesis of nanostructured Co-doped ZnO thin films and their magnetic properties

Through an understanding of the growth mechanism of diluted magnetic semiconductor (DMS) nanostructures, we tried to manipulate the performance of DMS-based devices. Under hydrothermal conditions, self-assembled complex nanostructures (flowers, sheaves, and cactuses) of Co-doped ZnO DMS thin films were selectively grown. Based on detailed scanning electron microscopy, energy-dispersive X-ray analysis, the sensitivity of the grazing incidence X-ray diffraction and transmission electron microscopy, the possible growth mechanism and phase analysis of the Co-doped ZnO nanostructures were proposed. The observation demonstrates that through self-assembly of 1D primary nanoparticles via oriented attachment or twinning coalescence, the transformation to 3D complex nanostructures was controlled. These novel Co-doped ZnO nanostructures exhibited enhanced ferromagnetism that can potentially improve the performance of spintronic devices. Our findings provide a better insight into the underlying growth mechanisms of the ferromagnetic Co-doped ZnO nanostructures.