Media effect on CdTe nanowire growth: Mechanism of self-assembly, Ostwald ripening, and control of NW geometry

The spontaneous self-assembly of II-IV stabilizer depleted nanoparticles (NPs) into nanowires (NWs) is a complex process that is only partially understood. This paper examines the mechanism governing changes in the growth pattern of CdTe NWs that are induced by the addition of dimethyl sulfoxide (DMSO) to the NW growth solution. We propose that, after the initial step of formation of NP pearl necklace assemblies, the assemblies recrystallize and subsequently grow into long NWs by Ostwald ripening. The addition of DMSO allows for improved control over the NW length and diameter. As the DMSO concentration in the NW growth solution is increased, the resulting NW length and diameter increase. When DMSO concentrations are raised above 70%; there is no NW formation, which is attributed to inhibition of the formation of pearl necklace assemblies. DMSO influence on NW morphology is attributed to its effect on the electrostatic interactions between the nanoparticles and mass exchange between the growing nuclei.