Essential role of catalysts (Mn, Au, and Sn) in the vapor liquid solid growth kinematics of ZnS nanowires

Abstract

In this paper, we demonstrate that surface energy of the catalyst is a vital parameter for the growth rate, self doping of the self assembled nanowires synthesized by employing vapor liquid solid growth technique. The synthesis of ZnS nanowires was done by selectively using three different catalysts (Mn, Au, and Sn), where Au, is the most common catalyst, was used as a reference. The distinctive difference in the growth rate was due to the surface energy of the metal alloy droplet and the interface energies, as explained theoretically using thermodynamic approach. We have found that the activation energy of diffusion of (Zn, S) species in the catalyst droplet was low in Sn (0.41 eV for Zn and 0.13 eV for S) and high in Mn (1.79 eV for Zn and 0.61 eV for S) compared to Au (0.62 eV for Zn and 0.21 eV for S) catalyzed ZnS nanostructures. The thermodynamic calculations predicted the growth rates of Sn (7.5 nm/s) catalyzed nanowires was faster than Au (5.1 nm/s) and Mn (4.6 nm/s) catalyzed ZnS nanostructures, which were in agreement with the experimental results. Finally, the location of the catalyst as dopant in the grown nanostructure was predicted and compared with experimental observations.