Growth of gold nanorods nucleated by HgTe nanoparticle seeds on various surfaces

We describe the synthesis of gold nanorods (NRs) nucleated by HgTe nanoparticles (NPs) of average size 3 nm in diameter. Growth of ~200 nm by ~50 nm NRs on various surfaces is achieved by using an intermediary polyelectrolyte layer. A poly(dimethyldiallylammonium) chloride (PDDA) monolayer on the surface attracts the thioglycolic acid (TGA) capped HgTe NPs and assists in one-dimensional gold growth. Rod morphology is observed for approximately one third of the resulting features. Confirmation of Au deposition is obtained with x-ray photoelectron spectroscopy and optical absorption measurements that show an increase in the Au plasmon band with time spent in gold growth solution. Au NRs were grown directly on the surface of high quality factor (Q) optical resonators (microspheres and microcylinders). Although the coating procedure reduces the Q of the resonators, whispering gallery modes are sustained. This seeding technique, amenable to many different surfaces, may result in semiconductor-metal nanocomposites with novel electronic and optical properties.