Sb₂O₃-Induced Tapered ZnO Nanowire Arrays: The Kinetics of Radial Growth and Morphology Control

Abstract

Controlling the morphology and understanding the underlying growth mechanism are essential for the synthesis of designed one-dimensional nanostructures. Here, a tapered ZnO nanowire array has been synthesized by catalyst-free thermal evaporation with a small amount of Sb2O3 additive in the precursors. The radial vapor-phase epitaxy growth is found to be responsible for the tapered structures. The kinetics of the radial growth is proposed to be modified by the adsorption of SbOx species on the nanocone surfaces, which may have a promotion effect on the two-dimensional nucleations and an inhibition effect on the advances of steps. As predicted, increasing the concentration of the Sb2O3 additive in the precursors has resulted in a morphology evolution from ZnO nanocones to more-tapered nanopillars, while the Sb doping concentration has not increased notably. The photoluminescence spectrum of the Sb-doped nanocones showed a red shifted and broadened near-band-edge emission. Our work demonstrates that Sb2O3 can be used as an effective additive to control the morphology of ZnO nanowires.