Dislocation-driven CdS and CdSe nanowire growth.

Abstract

We report the synthesis of CdS and CdSe nanowires (NWs) and nanoribbons (NRs) with gold catalysts by H(2)-assisted chemical vapor deposition. Nanopods and nanocones were obtained without catalysts at higher system pressure. Transmission electron microscopy (TEM) studies, including two-beam TEM and displaced-aperture dark-field TEM characterization, were used to investigate the NW growth mechanism. Dislocation contrast and twist contours have been routinely observed within the synthesized one-dimensional (1D) CdS and CdSe NWs, suggesting the operation of the dislocation-driven NW growth mechanism under our experimental conditions. The Burgers vectors of dislocations and the associated Eshelby twists were measured and quantified. We hypothesize that gold nanoparticles provide nucleation sites to initiate the growth of CdS/CdSe NWs and lead to the formation of dislocations that continue to drive and sustain 1D growth at a low supersaturation level. Our study suggests that the dislocation-driven mechanism may also contribute to the growth of other 1D nanomaterials that are commonly considered to grow via the vapor-liquid-solid mechanism.