Sixfold self-assembled hierarchical structures synthesized by direct annealing of Zn microtips

A facile route and the related mechanism for forming sixfold core–shell hierarchical structure with well-defined anisotropic three-dimensional arrays have been described. The regularity and symmetry of hierarchical structures prepared by annealing Zn microtips are superior to the random nanostructure arrays formed in general vapor system reported in the literature. Owing to the distinct stress distribution on the topography of microtips during annealing, the mechanism for growing branched zinc oxide (ZnO) nanowhiskers is related to the relaxation of stress. In addition, the self-assembled hierarchical structures with naturally good contact results in a lowered energy barrier between Zn metal and ZnO semiconductor, which in turn gives a much better emission property.