Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticlesNanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles
Faculty of Sciences. Physics
Electron microscopy for materials research (EMAT)
2016London :Nature Publishing Group, 2016
Engineering sciences. Technology
Scientific reports. - London, 2011, currens
6(2016), 8 p.
University of Antwerp
Metallic nanoparticles can be used to enhance optical absorption or emission in semiconductors, thanks to a strong interaction of collective excitations of free charges (plasmons) with electromagnetic fields. Herein we present direct imaging at the nanoscale of plasmon-exciton coupling in Au/ZnO nanostructures by combining scanning transmission electron energy loss and cathodoluminescence spectroscopy and mapping. The Au nanoparticles (~30 nm in diameter) are grown in-situ on ZnO nanotetrapods by means of a photochemical process without the need of binding agents or capping molecules, resulting in clean interfaces. Interestingly, the Au plasmon resonance is localized at the Au/vacuum interface, rather than presenting an isotropic distribution around the nanoparticle. On the contrary, a localization of the ZnO signal has been observed inside the Au nanoparticle, as also confirmed by numerical simulations.