Coalescence of ZnO nanowires grown from monodisperse Au nanoparticles

Abstract

New insights into control of nanowire merging phenomena are demonstrated in the growth of thin ZnO nanowires using monodisperse Au colloidal nanoparticles as a catalyst. Both the nanowire diameter and density were found to be strongly dependent on the density of Au nanoparticles. Structural analysis and spectral cathodoluminescence imaging of the c-plane nanowire cross-sections reveal that the thin isolated nanowires growing from the Au nanoparticles begin to merge and coalesce with neighbouring nanowires to form larger nanowires when their separation reaches a threshold distance. Green luminescence, which originated from the remnants of constituent nanowires before merging, is detected at the core of the fused nanowires. The distribution of nanowire diameters and green emission were found to be strongly dependent on the density of the Au nanoparticles. The merging phenomenon is attributed to electrostatic interactions between the nanowire c-facets during growth and well-described by a cantilever bending model.