Zinc blende 0D quantum dots to wurtzite 1D quantum wires: The oriented attachment and phase change in ZnSe nanostructures

Oriented attachment of nanocrystals has been recently studied as one of the important tools to organize the nanocrystals in a regular array to design new nanostructures. This is mostly a thermodynamically driven process where the nanocrystals align in a certain crystallographic direction and merge, minimizing the interfacial energy of the system during the course of reaction. While this has been widely studied for several group II-VI semiconductor nanocrystals, we explore herein ZnSe 0D quantum dots which on merging change to 1D quantum nanowires. Importantly, the phase of the nanocrystals is found to be transformed from zinc blende to wurtzite after the fusion. To understand this, we have analyzed the intermediate samples and studied the high-resolution transmission electron microscopy (HRTEM) of single, twin, and triple connected dots as well as the final nanowires and address the phase change during the shape conversion. Additionally, we have provided density functional theory (DFT) calculation to support our experimental observations.