Metallic nanovoid and nano hemisphere structures fabricated via simple methods to control localized surface plasmon resonances in UV and near IR wavelength regions

We introduce metal nanovoid (NV) and metal on metal nano-hemisphere (MoNH) structures to tune the localized surface plasmon resonance (LSPR) for wider wavelength ranges. The NV structures were constructed with metal layers on gallium oxide nano hemisphere (NH) structures, and the MoNH structures were constructed with dielectric layers and metal layers on random silver NH structures. These NH structures were fabricated via thermal annealing of the deposited metal thin films without top-down nanofabrication technologies. We verified both experimentally and numerically that NV and MoNH structures enable flexible tuning of the LSPR in the UV and NIR wavelength regions, respectively.