Revisiting the Growth Mechanism of Hierarchical Semiconductor Nanostructures: The Role of Secondary Nucleation in Branch Formation

Although advances in synthesizing hierarchical semiconductor materials, there have been few studies on the fundamental nucleation mechanisms to explain the origins of such complex structures. Resolving these nucleation and growth pathways is very difficult and time consuming, but is critical for developing predictive synthetic capabilities for the synthesis and applications of new materials. In this paper, we use state-of-the-art in-situ liquid phase scanning electron microscopy (SEM) and high-resolution transmission electron microscopy in combination of classical Density Functional Theory (cDFT) to study the nucleation of highly-branched wurtzite ZnO nanostructures via a facile, room temperature aqueous synthesis route. Using a range of precursor concentrations, we systematically vary their hierarchical organization. In situ liquid phase SEM demonstrates that all branches form through secondary nucleation and grow by classical processes. Neither random aggregation nor oriented attachment is observed. cDF...