Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles

• Main Authors: Bertoni, Giovanni (Author), Fabbri, Filippo (Author), Villani, Marco (Author), Lazzarini, Laura (Author), Turner, Stuart (Author), Van Tendeloo, Gustaaf (Author), Calestani, Davide (Author), Gradecak, Silvija (Contributor), Zappettini, Andrea (Author), Salviati, Giancarlo (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Materials Science and Engineering (Contributor)
• Format: Article
• Language: English
• Published: Nature Publishing Group, 2016-03-18T16:18:05Z.
• Subjects: Article
• Online Access: Get fulltext

 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.